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flowering plants, but the exact nature of how the genes respond to each mechanism might differ between species. = = = vernalization = = = vernalization depends on the presence of a long non - coding rna that is termed coldair. the exposure of plants to a significant period of cold results in coldair accumulation. coldair targets polycomb repressive complex 2 which acts to silence flowering locus c through methylation. as flowering locus c is repressed it no longer acts to inhibit the transcription of flowering locus t and soc1. flowering locus t and soc1 activity leads to the development of flowers. = = = photoperiodism = = = another set of flowering controls stems from photoperiodism which initiates flowering based on the length of nighttime. long day plants flower with a short night, while short day plants require uninterrupted darkness. some plants are restricted to either condition, while others can operate under a combination of the two, and some plants do not operate under photoperiodism. in arabidopsis, the gene constans responds to long day conditions and enables flowering when it stops repressing flowering locus t. in rice, photoperiodic response is slightly more complex and is controlled by the florigen genes rice flowering locus t 1 ( rft1 ) and heading date 3 a ( hd3a ). hd3a, is a homolog of flowering locus t and, when no longer repressed, activates flowering by directing modification of dna at the shoot apical meristem with florigen. heading date 1 ( hd1 ) is a gene that promotes flowering under short day conditions but represses flowering under long day as it either activates or suppresses hd3a. meanwhile, rft1 can cause flowering under non - inductive long day. polycomb repressive complex 2 can lead to silencing of the genes through histone h3 lysine 27 trimethylation. a variety of chromatin modifications operating in both long and short days or only under one condition can also affect the two florigen genes in rice. = = flowering wageningen ( fwa ) = = the gene fwa has been identified as responsible for late flowering in epi - mutants. epi - mutants are individuals with particular epigenetic changes that lead to a distinct phenotype. as such, both wild type and epi - mutant variants contain identical sequences for fwa. loss of methylation in direct repeats in
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mutants. epi - mutants are individuals with particular epigenetic changes that lead to a distinct phenotype. as such, both wild type and epi - mutant variants contain identical sequences for fwa. loss of methylation in direct repeats in the 5'region of the gene results in expression of fwa and subsequent prevention of proper flowering. the gene is normally silenced by methylation of dna in tissues not related to flowering ( soppe et al. 2000 ). = = meristematic tissue = = meristematic tissues contain cells that continue to grow and differentiate throughout the plant's lifetime. shoot apical meristem gives rise to flowers and leaves while root apical meristem grows into roots. these components are crucial to general plant growth and are the harbingers of development. meristematic tissue apparently contains characteristic epigenetic modifications. for example, the boundary between the proximal meristem and elongation zone showed elevated h4k5ac along with a high level of 5mc in barley. root meristematic tissues have been found to contain patterns for histone h4 lysine 5 acetylation, histone h3 lysine 4 and 9 di methylation and dna methylation as 5 - methyl cytosine. so far, only a causal correlation between epigenetic marks and tissue types has been established and further study is required to understand the exact involvement of the marks. = = heterosis = = heterosis is defined as any advantages seen in hybrids. the effects of heterosis seem to follow a rather simple epigenetic premise in plants. in hybrids, lack of proper regulatory action, such as silencing by methylation, leads to uninhibited genes. if the gene is involved in growth, such as photosynthesis, the plant will experience increased vitality. the results heterosis can be seen in traits such as increased fruit yield, earlier ripening, and heat tolerance. heterosis has been shown to provide increased general growth and fruit yield in tomato plants. = = references = = = = further reading = =
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the lipidome refers to the totality of lipids in cells. lipids are one of the four major molecular components of biological organisms, along with proteins, sugars and nucleic acids. lipidome is a term coined in the context of omics in modern biology, within the field of lipidomics. it can be studied using mass spectrometry and bioinformatics as well as traditional lab - based methods. the lipidome of a cell can be subdivided into the membrane - lipidome and mediator - lipidome. the first cell lipidome to be published was that of a mouse macrophage in 2010. the lipidome of the yeast saccharomyces cerevisiae has been characterised with an estimated 95 % coverage ; studies of the human lipidome are ongoing. for example, the human plasma lipidome consist of almost 600 distinct molecular species. research suggests that the lipidome of an individual may be able to indicate cancer risks associated with dietary fats, particularly breast cancer. = = see also = = genome proteome glycome = = references = = = = further reading = = = = external links = = lipidomics gateway
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the surgical sieve is a thought process in medicine. it is a typical example of how to organise a structured examination answer for medical students and physicians when they are challenged with a question. it is also a way of constructing answers to questions from patients and their relatives in a logical manner, and structuring articles and reference texts in medicine. some textbooks put emphasis on using the surgical sieve as a basic structure of diagnosis and management of illnesses. = = overview = = although there are several versions around the world with slight variations, the surgical sieve usually consist of the following types of process in the human body in any particular order : congenital acquired vascular infective traumatic autoimmune metabolic inflammatory neurological neoplastic degenerative environmental unknown a more extensive, and perhaps more concise mechanism of employing the surgical sieve is using the mnemonic medic hat pine : metabolic ( conditions relating to metabolism, biochemistry, and the like ) endocrinological ( conditions relating to the various secretory systems within the body ) degenerative ( conditions relating to age - related destruction of tissue, or stress - related destruction of tissue ) inflammatory / infective ( conditions that primarily present in a way that involves the profane activation of the immune system ) congenital ( conditions present at birth ) genetic / inherited ( conditions that your family passes on to you ) haematological ( conditions relating to the blood system, in one way or another ) autoimmune ( conditions relating to the inappropriate activation of the immune system, in one of many ways ) traumatic ( conditions relating to a physical impact between two or more objects ) psychological ( conditions related to a chemical imbalance or a disorder of thought processes ) neurological ( conditions relating to the nervous system, in one way or another β whether that be the central or peripheral ) idiopathic ( conditions without a known cause ) iatrogenic ( lit. translation β doctor caused β - or resulting from treatment ) neoplastic ( conditions relating to cancers ) environmental ( conditions relating to exposures, and dose - response relationships thereof ) = = examples = = what are the causes of an acute confusional state in a patient? treatment induced ( iatrogenic ) : polypharmacy, sedatives, analgesics, steroids, drug withdrawal vascular : stroke, tia, vascular dementia inflammatory : infection, systemic inflammatory response syndrome traumatic : head injury, intracranial hemorrhage, shock autoimmune : thyroid disease metabolic : electrolyte imbalance, dka, h
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withdrawal vascular : stroke, tia, vascular dementia inflammatory : infection, systemic inflammatory response syndrome traumatic : head injury, intracranial hemorrhage, shock autoimmune : thyroid disease metabolic : electrolyte imbalance, dka, hypoglycaemia, siadh infective : sepsis, local infection neoplastic : brain tumour, carcinomatosis degenerative : alzheimer's disease, dementia what are the causes of splenomegaly? idiopathic : idiopathic thrombocytopenic purpura vascular : portal vein obstruction, budd - chiari syndrome, haemoglobinopathies ( sickle - cell disease, thalassemia ) infective : aids, mononucleosis, septicaemia, tuberculosis, brucellosis, malaria, infective endocarditis traumatic : haematoma, rupture autoimmune : rheumatoid arthritis, sle metabolic : gaucher's disease, mucopolysaccharidoses, amyloidosis, tangier disease inflammatory : sarcoidosis neoplastic : cml, metastases, myeloproliferative disorders = = in popular culture = = the surgical sieve is frequently used by gregory house, who is a physician in the tv series house in order to diagnose the rare diseases his patients suffer from. in some episodes various forms of the surgical sieve are scribbled on to house's whiteboard while his team struggle to diagnose difficult cases. in the episode'paternity'the mnemonic'midnit'is used to run through the sieve ( metabolic, inflammation, degenerative, neoplastic, infection, trauma ). = = see also = = trauma surgery hypnosurgery surgery = = references = =
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in mathematics, computer science and especially graph theory, a distance matrix is a square matrix ( two - dimensional array ) containing the distances, taken pairwise, between the elements of a set. depending upon the application involved, the distance being used to define this matrix may or may not be a metric. if there are n elements, this matrix will have size nΓn. in graph - theoretic applications, the elements are more often referred to as points, nodes or vertices. = = non - metric distance matrix = = in general, a distance matrix is a weighted adjacency matrix of some graph. in a network, a directed graph with weights assigned to the arcs, the distance between two nodes of the network can be defined as the minimum of the sums of the weights on the shortest paths joining the two nodes ( where the number of steps in the path is bounded ). this distance function, while well defined, is not a metric. there need be no restrictions on the weights other than the need to be able to combine and compare them, so negative weights are used in some applications. since paths are directed, symmetry can not be guaranteed, and if negative - weight cycles exist the distance matrix may not be hollow ( and in the absence of a bound on the step count, the matrix may be undefined ). an algebraic formulation of the above can be obtained by using the min - plus algebra. matrix multiplication in this system is defined as follows : given two n Γ n matrices a = ( aij ) and b = ( bij ), their distance product c = ( cij ) = a b is defined as an n Γ n matrix such that c i j = min k = 1 n { a i k + b k j }. { \ displaystyle c _ { ij } = \ min _ { k = 1 } ^ { n } \ { a _ { ik } + b _ { kj } \ }. } note that the off - diagonal elements that are not connected directly will need to be set to infinity or a suitable large value for the min - plus operations to work correctly. a zero in these locations will be incorrectly interpreted as an edge with no distance, cost, etc. if w is an n Γ n matrix containing the edge weights of a graph, then wk ( using this distance product ) gives the distances between vertices using paths of length at most k edges, and so is the distance matrix of the graph when the step count bound is set to k. if
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the edge weights of a graph, then wk ( using this distance product ) gives the distances between vertices using paths of length at most k edges, and so is the distance matrix of the graph when the step count bound is set to k. if there are no loops of negative weight, wn will give the true distance matrix, with no bound, because removing repeated vertices from a path cannot lower its weight. on the other hand, if i and j are on a negative - weight loop, wkij will decrease without bound as k increases. an arbitrary graph g on n vertices can be modeled as a weighted complete graph on n vertices by assigning a weight of one to each edge of the complete graph that corresponds to an edge of g and infinity to all other edges. w for this complete graph is the adjacency matrix of g. the distance matrix of g can be computed from w as above ; by contrast, if normal matrix multiplication is used, and unlinked vertices are represented with 0, wn would instead encode the number of paths between any two vertices of length exactly n. = = metric distance matrix = = the value of a distance matrix formalism in many applications is in how the distance matrix can manifestly encode the metric axioms and in how it lends itself to the use of linear algebra techniques. that is, if m = ( xij ) with 1 β€ i, j β€ n is a distance matrix for a metric distance, then the entries on the main diagonal are all zero ( that is, the matrix is a hollow matrix ), i. e. xii = 0 for all 1 β€ i β€ n, all the off - diagonal entries are positive ( xij > 0 if i = j ), ( that is, a non - negative matrix ), the matrix is a symmetric matrix ( xij = xji ), and for any i and j, xij β€ xik + xkj for all k ( the triangle inequality ). this can be stated in terms of tropical matrix multiplication when a distance matrix satisfies the first three axioms ( making it a semi - metric ) it is sometimes referred to as a pre - distance matrix. a pre - distance matrix that can be embedded in a euclidean space is called a euclidean distance matrix. for mixed - type data that contain numerical as well as categorical descriptors, gower's distance is a common alternative. another common example of a metric distance matrix arises in coding theory when in a block code the
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a euclidean distance matrix. for mixed - type data that contain numerical as well as categorical descriptors, gower's distance is a common alternative. another common example of a metric distance matrix arises in coding theory when in a block code the elements are strings of fixed length over an alphabet and the distance between them is given by the hamming distance metric. the smallest non - zero entry in the distance matrix measures the error correcting and error detecting capability of the code. = = additive distance matrix = = an additive distance matrix is a special type of matrix used in bioinformatics to build a phylogenetic tree. let x be the lowest common ancestor between two species i and j, we expect mij = mix + mxj. this is where the additive metric comes from. a distance matrix m for a set of species s is said to be additive if and only if there exists a phylogeny t for s such that : every edge ( u, v ) in t is associated with a positive weight duv for every i, j β s, mij equals the sum of the weights along the path from i to j in t for this case, m is called an additive matrix and t is called an additive tree. below we can see an example of an additive distance matrix and its corresponding tree : = = ultrametric distance matrix = = the ultrametric distance matrix is defined as an additive matrix which models the constant molecular clock. it is used to build a phylogenetic tree. a matrix m is said to be ultrametric if there exists a tree t such that : mij equals the sum of the edge weights along the path from i to j in t a root of the tree can be identified with the distance to all the leaves being the same here is an example of an ultrametric distance matrix with its corresponding tree : = = bioinformatics = = the distance matrix is widely used in the bioinformatics field, and it is present in several methods, algorithms and programs. distance matrices are used to represent protein structures in a coordinate - independent manner, as well as the pairwise distances between two sequences in sequence space. they are used in structural and sequential alignment, and for the determination of protein structures from nmr or x - ray crystallography. sometimes it is more convenient to express data as a similarity matrix. it is also used to define the distance correlation. = = = sequence alignment = = = an alignment of two sequences is formed by inserting spaces in arbitrary locations along the sequences so that they end
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is more convenient to express data as a similarity matrix. it is also used to define the distance correlation. = = = sequence alignment = = = an alignment of two sequences is formed by inserting spaces in arbitrary locations along the sequences so that they end up with the same length and there are no two spaces at the same position of the two augmented sequences. one of the primary methods for sequence alignment is dynamic programming. the method is used to fill the distance matrix and then obtain the alignment. in typical usage, for sequence alignment a matrix is used to assign scores to amino - acid matches or mismatches, and a gap penalty for matching an amino - acid in one sequence with a gap in the other. = = = = global alignment = = = = the needleman β wunsch algorithm used to calculate global alignment uses dynamic programming to obtain the distance matrix. = = = = local alignment = = = = the smith β waterman algorithm is also dynamic programming based which consists also in obtaining the distance matrix and then obtain the local alignment. = = = = multiple sequence alignment = = = = multiple sequence alignment is an extension of pairwise alignment to align several sequences at a time. different msa methods are based on the same idea of the distance matrix as global and local alignments. center star method. this method defines a center sequence sc which minimizes the distance between the sequence sc and any other sequence si. then it generates a multiple alignment m for the set of sequences s so that for every si the alignment distance dm ( sc, si ) is the optimal pairwise alignment. this method has the characteristic that the computed alignment for s whose sum - of - pair distance is at most twice the optimal multiple alignment. progressive alignment method. this heuristic method to create msa first aligns the two most related sequences, and then it progressively aligns the next two most related sequences until all sequences are aligned. there are other methods that have their own program due to their popularity : clustalw muscle mafft mango and many more = = = = = mafft = = = = = multiple alignment using fast fourier transform ( mafft ) is a program with an algorithm based on progressive alignment, and it offers various multiple alignment strategies. first, mafft constructs a distance matrix based on the number of shared 6 - tuples. second, it builds the guide tree based on the previous matrix. third, it clusters the sequences with the help of the fast fourier transform and starts the alignment. based on
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constructs a distance matrix based on the number of shared 6 - tuples. second, it builds the guide tree based on the previous matrix. third, it clusters the sequences with the help of the fast fourier transform and starts the alignment. based on the new alignment, it reconstructs the guide tree and align again. = = = phylogenetic analysis = = = to perform phylogenetic analysis, the first step is to reconstruct the phylogenetic tree : given a collection of species, the problem is to reconstruct or infer the ancestral relationships among the species, i. e., the phylogenetic tree among the species. distance matrix methods perform this activity. = = = = distance matrix methods = = = = distance matrix methods of phylogenetic analysis explicitly rely on a measure of " genetic distance " between the sequences being classified, and therefore require multiple sequences as an input. distance methods attempt to construct an all - to - all matrix from the sequence query set describing the distance between each sequence pair. from this is constructed a phylogenetic tree that places closely related sequences under the same interior node and whose branch lengths closely reproduce the observed distances between sequences. distance - matrix methods may produce either rooted or unrooted trees, depending on the algorithm used to calculate them. given n species, the input is an n Γ n distance matrix m where mij is the mutation distance between species i and j. the aim is to output a tree of degree 3 which is consistent with the distance matrix. they are frequently used as the basis for progressive and iterative types of multiple sequence alignment. the main disadvantage of distance - matrix methods is their inability to efficiently use information about local high - variation regions that appear across multiple subtrees. despite potential problems, distance methods are extremely fast, and they often produce a reasonable estimate of phylogeny. they also have certain benefits over the methods that use characters directly. notably, distance methods allow use of data that may not be easily converted to character data, such as dna β dna hybridization assays. the following are distance based methods for phylogeny reconstruction : additive tree reconstruction upgma neighbor joining fitch β margoliash = = = = = additive tree reconstruction = = = = = additive tree reconstruction is based on additive and ultrametric distance matrices. these matrices have a special characteristic : consider an additive matrix m. for any three species i, j, k, the corresponding tree is unique. every ultrametric distance matrix is an additive matrix. we can observe this property for the tree below, which consists
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matrices have a special characteristic : consider an additive matrix m. for any three species i, j, k, the corresponding tree is unique. every ultrametric distance matrix is an additive matrix. we can observe this property for the tree below, which consists on the species i, j, k. the additive tree reconstruction technique starts with this tree. and then adds one more species each time, based on the distance matrix combined with the property mentioned above. for example, consider an additive matrix m and 5 species a, b, c, d and e. first we form an additive tree for two species a and b. then we chose a third one, let's say c and attach it to a point x on the edge between a and b. the edge weights are computed with the property above. next we add the fourth species d to any of the edges. if we apply the property then we identify that d should be attached to only one specific edge. finally, we add e following the same procedure as before. = = = = = upgma = = = = = the basic principle of upgma ( unweighted pair group method with arithmetic mean ) is that similar species should be closer in the phylogenetic tree. hence, it builds the tree by clustering similar sequences iteratively. the method works by building the phylogenetic tree bottom up from its leaves. initially, we have n leaves ( or n singleton trees ), each representing a species in s. those n leaves are referred as n clusters. then, we perform n - 1 iterations. in each iteration, we identify two clusters c1 and c2 with the smallest average distance and merge them to form a bigger cluster c. if we suppose m is ultrametric, for any cluster c created by the upgma algorithm, c is a valid ultrametric tree. = = = = = neighbor joining = = = = = neighbor is a bottom - up clustering method. it takes a distance matrix specifying the distance between each pair of sequences. the algorithm starts with a completely unresolved tree, whose topology corresponds to that of a star network, and iterates over the following steps until the tree is completely resolved and all branch lengths are known : based on the current distance matrix calculate the matrix ( defined below ). find the pair of distinct taxa i and j ( i. e. with ) for which has its lowest value. these taxa are joined to a newly created node, which is connected to the central node. calculate the distance from each of the taxa
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. find the pair of distinct taxa i and j ( i. e. with ) for which has its lowest value. these taxa are joined to a newly created node, which is connected to the central node. calculate the distance from each of the taxa in the pair to this new node. calculate the distance from each of the taxa outside of this pair to the new node. start the algorithm again, replacing the pair of joined neighbors with the new node and using the distances calculated in the previous step. = = = = = fitch β margoliash = = = = = the fitch β margoliash method uses a weighted least squares method for clustering based on genetic distance. closely related sequences are given more weight in the tree construction process to correct for the increased inaccuracy in measuring distances between distantly related sequences. the least - squares criterion applied to these distances is more accurate but less efficient than the neighbor - joining methods. an additional improvement that corrects for correlations between distances that arise from many closely related sequences in the data set can also be applied at increased computational cost. = = data mining and machine learning = = = = = data mining = = = a common function in data mining is applying cluster analysis on a given set of data to group data based on how similar or more similar they are when compared to other groups. distance matrices became heavily dependent and utilized in cluster analysis since similarity can be measured with a distance metric. thus, distance matrix became the representation of the similarity measure between all the different pairs of data in the set. = = = = hierarchical clustering = = = = a distance matrix is necessary for traditional hierarchical clustering algorithms which are often heuristic methods employed in biological sciences such as phylogeny reconstruction. when implementing any of the hierarchical clustering algorithms in data mining, the distance matrix will contain all pair - wise distances between every point and then will begin to create clusters between two different points or clusters based entirely on distances from the distance matrix. if n be the number of points, the complexity of hierarchical clustering is : time complexity is o ( n 3 ) { \ displaystyle o ( n ^ { 3 } ) } due to the repetitive calculations done after every cluster to update the distance matrix space complexity is o ( n 2 ) { \ displaystyle o ( n ^ { 2 } ) } = = = machine learning = = = distance metrics are a key part of several machine learning algorithms, which are used in both supervised and unsupervised learning. they are
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{ \ displaystyle o ( n ^ { 2 } ) } = = = machine learning = = = distance metrics are a key part of several machine learning algorithms, which are used in both supervised and unsupervised learning. they are generally used to calculate the similarity between data points : this is where the distance matrix is an essential element. the use of an effective distance matrix improves the performance of the machine learning model, whether it is for classification tasks or for clustering. = = = = k - nearest neighbors = = = = a distance matrix is utilized in the k - nn algorithm which is one of the slowest but simplest and most used instance - based machine learning algorithms that can be used both in classification and regression tasks. it is one of the slowest machine learning algorithms since each test sample's predicted result requires a fully computed distance matrix between the test sample and each training sample in the training set. once the distance matrix is computed, the algorithm selects the k number of training samples that are the closest to the test sample to predict the test sample's result based on the selected set's majority ( classification ) or average ( regression ) value. prediction time complexity is o ( k β n β d ) { \ displaystyle o ( k * n * d ) }, to compute the distance between each test sample with every training sample to construct the distance matrix where : k = number of nearest neighbors selected n = size of the training set d = number of dimensions being used for the data this classification focused model predicts the label of the target based on the distance matrix between the target and each of the training samples to determine the k - number of samples that are the closest / nearest to the target. = = = computer vision = = = a distance matrix can be used in neural networks for 2d to 3d regression in image predicting machine learning models. = = information retrieval = = = = = distance matrices using gaussian mixture distance = = = [ 1 ] * gaussian mixture distance for performing accurate nearest neighbor search for information retrieval. under an established gaussian finite mixture model for the distribution of the data in the database, the gaussian mixture distance is formulated based on minimizing the kullback - leibler divergence between the distribution of the retrieval data and the data in database. in the comparison of performance of the gaussian mixture distance with the well - known euclidean and mahalanobis distances based on a precision performance measurement, experimental results demonstrate that the gaussian mixture distance
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of the retrieval data and the data in database. in the comparison of performance of the gaussian mixture distance with the well - known euclidean and mahalanobis distances based on a precision performance measurement, experimental results demonstrate that the gaussian mixture distance function is superior in the others for different types of testing data. potential basic algorithms worth noting on the topic of information retrieval is fish school search algorithm an information retrieval that partakes in the act of using distance matrices in order for gathering collective behavior of fish schools. by using a feeding operator to update their weights eq. a : x i ( t + 1 ) = x i ( t ) β s t e p v o l r a n d ( 0, 1 ) x i ( t ) β b ( t ) d i s t a n c e ( x i ( t ), b ( t ) ), { \ displaystyle x _ { i } ( t + 1 ) = x _ { i } ( t ) - step _ { vol } rand ( 0, 1 ) { \ frac { x _ { i } ( t ) - b ( t ) } { distance ( x _ { i } ( t ), b ( t ) ) } }, } eq. b : x i ( t + 1 ) = x i ( t ) + s t e p v o l r a n d ( 0, 1 ) x i ( t ) β b ( t ) d i s t a n c e ( x i ( t ), b ( t ) ), { \ displaystyle x _ { i } ( t + 1 ) = x _ { i } ( t ) + step _ { vol } rand ( 0, 1 ) { \ frac { x _ { i } ( t ) - b ( t ) } { distance ( x _ { i } ( t ), b ( t ) ) } }, } stepvol defines the size of the maximum volume displacement preformed with the distance matrix, specifically using a euclidean distance matrix. = = = evaluation of the similarity or dissimilarity of cosine similarity and distance matrices = = = [ 2 ] * while the cosine similarity measure is perhaps the most frequently applied proximity measure in information retrieval by measuring the angles between documents in the search space on the base of the cosine. euclidean distance is invariant to mean - correction. the sampling distribution of a mean is generated by repeated sampling from the same population and recording of the sample
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information retrieval by measuring the angles between documents in the search space on the base of the cosine. euclidean distance is invariant to mean - correction. the sampling distribution of a mean is generated by repeated sampling from the same population and recording of the sample means obtained. this forms a distribution of different means, and this distribution has its own mean and variance. for the data which can be negative as well as positive, the null distribution for cosine similarity is the distribution of the dot product of two independent random unit vectors. this distribution has a mean of zero and a variance of 1 / n. while euclidean distance will be invariant to this correction. = = = clustering documents = = = the implementation of hierarchical clustering with distance - based metrics to organize and group similar documents together will require the need and utilization of a distance matrix. the distance matrix will represent the degree of association that a document has with another document that will be used to create clusters of closely associated documents that will be utilized in retrieval methods of relevant documents for a user's query. = = = isomap = = = isomap incorporates distance matrices to utilize geodesic distances to able to compute lower - dimensional embeddings. this helps to address a collection of documents that reside within a massive number of dimensions and empowers to perform document clustering. = = = neighborhood retrieval visualizer ( nerv ) = = = an algorithm used for both unsupervised and supervised visualization that uses distance matrices to find similar data based on the similarities shown on a display / screen. the distance matrix needed for unsupervised nerv can be computed through fixed input pairwise distances. the distance matrix needed for supervised nerv requires formulating a supervised distance metric to be able to compute the distance of the input in a supervised manner. = = chemistry = = the distance matrix is a mathematical object widely used in both graphical - theoretical ( topological ) and geometric ( topographic ) versions of chemistry. the distance matrix is used in chemistry in both explicit and implicit forms. = = = interconversion mechanisms between two permutational isomers = = = distance matrices were used as the main approach to depict and reveal the shortest path sequence needed to determine the rearrangement between the two permutational isomers. = = = distance polynomials and distance spectra = = = explicit use of distance matrices is required in order to construct the distance polynomials and distance spectra of molecular structures. = = = structure - property model = = =
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two permutational isomers. = = = distance polynomials and distance spectra = = = explicit use of distance matrices is required in order to construct the distance polynomials and distance spectra of molecular structures. = = = structure - property model = = = implicit use of distance matrices was applied through the use of the distance based metric weiner number / weiner index which was formulated to represent the distances in all chemical structures. the weiner number is equal to half - sum of the elements of the distance matrix. = = = graph - theoretical distance matrix = = = distance matrix in chemistry that are used for the 2 - d realization of molecular graphs, which are used to illustrate the main foundational features of a molecule in a myriad of applications. creating a label tree that represents the carbon skeleton of a molecule based on its distance matrix. the distance matrix is imperative in this application because similar molecules can have a myriad of label tree variants of their carbon skeleton. the labeled tree structure of hexane ( c6h14 ) carbon skeleton that is created based on the distance matrix in the example, has different carbon skeleton variants that affect both the distance matrix and the labeled tree creating a labeled graph with edge weights, used in chemical graph theory, that represent molecules with hetero - atoms. le verrier - fadeev - frame ( lvff ) method is a computer oriented used to speed up the process of detecting the graph center in polycyclic graphs. however, lvff requires the input to be a diagonalized distance matrix which is easily resolved by implementing the householder tridiagonal - ql algorithm that takes in a distance matrix and returns the diagonalized distance needed for the lvff method. = = = geometric - distance matrix = = = while the graph - theoretical distance matrix 2 - d captures the constitutional features of the molecule, its three - dimensional ( 3d ) character is encoded in the geometric - distance matrix. the geometric - distance matrix is a different type of distance matrix that is based on the graph - theoretical distance matrix of a molecule to represent and graph the 3 - d molecule structure. the geometric - distance matrix of a molecular structure g is a real symmetric n x n matrix defined in the same way as a 2 - d matrix. however, the matrix elements dij will hold a collection of shortest cartesian distances between i and j in g. also known as topographic matrix, the geometric - distance matrix can be constructed from the known geometry of the molecule. as an example, the geometric - distance matrix of the carbon skeleton
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hold a collection of shortest cartesian distances between i and j in g. also known as topographic matrix, the geometric - distance matrix can be constructed from the known geometry of the molecule. as an example, the geometric - distance matrix of the carbon skeleton of 2, 4 - dimethylhexane is shown below : = = other applications = = = = = time series analysis = = = dynamic time warping distance matrices are utilized with the clustering and classification algorithms of a collection / group of time series objects. = = examples = = for example, suppose these data are to be analyzed, where pixel euclidean distance is the distance metric. the distance matrix would be : these data can then be viewed in graphic form as a heat map. in this image, black denotes a distance of 0 and white is maximal distance. = = see also = = computer vision data clustering distance set hollow matrix min - plus matrix multiplication = = references = =
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a mechanical rectifier is a device for converting alternating current ( ac ) to direct current ( dc ) by means of mechanically operated switches. the best - known type is the commutator, which is an integral part of a dc dynamo, but before solid - state devices became available, independent mechanical rectifiers were used for certain applications. before the invention of semiconductors, rectification at high currents involved serious losses. there were various vacuum / gas devices, such as the mercury arc rectifiers, thyratrons, ignitrons, and vacuum diodes. solid - state technology was in its infancy, represented by copper oxide and selenium rectifiers. all of these gave excessive forward voltage drop at high currents. one answer was mechanically opening and closing contacts, if this could be done quickly and cleanly enough. = = vibrator type = = this was the reverse of a vibrator inverter. an electromagnet, powered by dc through contacts it operated ( like a buzzer ) ( or fed with ac ), caused a spring to vibrate and the spring - operated change - over contacts which converted the ac to dc. this arrangement was only suitable for low - power applications, e. g. auto radios and was also found in some motorcycle electrical systems, where it was combined with a voltage regulator. = = motor - driven type = = this operated on the same principle as the vibrator type but the change - over contacts were operated by a synchronous motor. it was suitable for high - power applications, e. g. electrolysis cells and electrostatic precipitators. = = = still rectifier = = = a mechanical rectifier was patented in 1895 ( us patent 547043 ) by william joseph still. the details are obscure but it appears from the diagram to be similar to a third - brush dynamo. = = = bth rectifier = = = the machine shown in the reference was designed by read and gimson et al., at british thomson - houston ( bth ) rugby, warwickshire, england, in the early 1950s. it is a three - phase mechanical rectifier working at 220 volts and 15, 000 amperes, and its application was the powering of huge banks of electrolysis cells. the central shaft was rotated by synchronous motor, driving an eccentric with a throw of about 2mm. ( 0. 077 inch ) push -
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amperes, and its application was the powering of huge banks of electrolysis cells. the central shaft was rotated by synchronous motor, driving an eccentric with a throw of about 2mm. ( 0. 077 inch ) push - rods from this operated the contacts. the timing was critical, and was adjusted by rotating the position of the eccentric on its shaft, and by sliding wedges between the eccentric and push - rods. crucial to this system were the commutating reactors, inductors that ensured the contacts closed when the voltage across them was small, and opened when the current was small. without these, contact wear would have been intolerably heavy. these were series inductors that operated for most of the cycle with saturated cores. when the current decreased below that for saturation, their inductances reduced the current considerably. contact switching was timed to occur while their cores were un - saturated. in the usa, similar rectifiers were made by the i - t - e circuit breaker company. this machinery was undoubtedly successful ; its efficiency was determined to be 97. 25 %. contact life was never fully determined but considerably exceeded 2000 hours. however, the rapid development of the silicon diode made it ultimately redundant. = = references = =
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novel ecosystems are human - built, modified, or engineered niches of the anthropocene. they exist in places that have been altered in structure and function by human agency. novel ecosystems are part of the human environment and niche ( including urban, suburban, and rural ), they lack natural analogs, and they have extended an influence that has converted more than three - quarters of wild earth. these anthropogenic biomes include technoecosystems that are fuelled by powerful energy sources ( fossil and nuclear ) including ecosystems populated with technodiversity, such as roads and unique combinations of soils called technosols. vegetation associations on old buildings or along field boundary stone walls in old agricultural landscapes are examples of sites where research into novel ecosystem ecology is developing. = = overview = = human society has transformed the planet to such an extent that we may have ushered in a new epoch known as the anthropocene. the ecological niche of the anthropocene contains entirely novel ecosystems that include technosols, technodiversity, anthromes, and the technosphere. these terms describe the human ecological phenomena marking this unique turn in the evolution of earth's history. the total human ecosystem ( or anthrome ) describes the relationship of the industrial technosphere to the ecosphere. technoecosystems interface with natural life - supporting ecosystems in competitive and parasitic ways. odum ( 2001 ) attributes this term to a 1982 publication by zev naveh : " current urban - industrial society not only impacts natural life - support ecosystems, but also has created entirely new arrangements that we can call techno - ecosystems, a term believed to be first suggested by zev neveh ( 1982 ). these new systems involve new, powerful energy sources ( fossil and atomic fuels ), technology, money, and cities that have little or no parallels in nature. " : 137 the term technoecosystem, however, appears earliest in print in a 1976 technical report and also appears in a book chapter ( see in lamberton and thomas ( 1982 ) written by kenneth e. boulding ). = = novel ecosystems = = novel ecosystems " differ in composition and / or function from present and past systems ". novel ecosystems are the hallmark of the recently proposed anthropocene epoch. they have no natural analogs due to human alterations on global climate systems, invasive species, a global mass extinction, and disruption of the global nitrogen cycle. novel ecosystems are creating many different kinds of dilemmas for terrestrial and
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anthropocene epoch. they have no natural analogs due to human alterations on global climate systems, invasive species, a global mass extinction, and disruption of the global nitrogen cycle. novel ecosystems are creating many different kinds of dilemmas for terrestrial and marine conservation biologists. on a more local scale, abandoned lots, agricultural land, old buildings, field boundary stone walls or residential gardens provide study sites on the history and dynamics of ecology in novel ecosystems. a defining feature of novel ecosystems is " practical unrestorability " because either so many native species have gone extinct, or the original landscape has been so changed, in tandem with naturalization of non - native species into a self - sustaining integrated whole that is unlikely to rolled back to some previous " natural state. " famous insular novel ecosystems include ascension island and oahu. = = = anthropogenic biomes = = = ellis ( 2008 ) identifies twenty - one different kinds of anthropogenic biomes that sort into the following groups : 1 ) dense settlements, 2 ) villages, 3 ) croplands, 4 ) rangeland, 5 ) forested, and 6 ) wildlands. these anthropogenic biomes ( or anthromes for short ) create the technosphere that surrounds us and are populated with diverse technologies ( or technodiversity for short ). within these anthromes the human species ( one species out of billions ) appropriates 23. 8 % of the global net primary production. " this is a remarkable impact on the biosphere caused by just one species. " = = = noosphere = = = noosphere ( sometimes noosphere ) is the " sphere of human thought ". the word is derived from the greek Ξ½ΞΏΟ
Ο ( nous " mind " ) + ΟΟΞ±ΞΉΟΞ± ( sphaira " sphere " ), in lexical analogy to " atmosphere " and " biosphere ". introduced by pierre teilhard de chardin 1922 in his cosmogenesis. another possibility is the first use of the term by edouard le roy, who together with chardin was listening to lectures of vladimir vernadsky at sorbonne. in 1936 vernadsky presented on the idea of the noosphere in a letter to boris leonidovich lichkov ( though, he states that the concept derives from le roy ). = = = technosphere = = = the technosphere is the part of the environment on earth where technodiversity extends its influence into the biosphere. " for the development of suitable restoration
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he states that the concept derives from le roy ). = = = technosphere = = = the technosphere is the part of the environment on earth where technodiversity extends its influence into the biosphere. " for the development of suitable restoration strategies, a clear distinction has to be made between different functional classes of natural and cultural solar - powered biosphere and fossil - powered technosphere landscapes, according to their inputs and throughputs of energy and materials, their organisms, their control by natural or human information, their internal self - organization and their regenerative capacities. " the weight of earth's technosphere has been suggested to be 30 trillion tons, a mass greater than 50 kilos for every square metre of the planet's surface. = = = technoecosystems = = = the concept of technoecosystems has been pioneered by ecologists howard t. odum and zev naveh. technoecosystems interfere with and compete against natural systems. they have advanced technology ( or technodiversity ) money - based market economies and have a large ecological footprints. technoecosystems have far greater energy requirements than natural ecosystems, excessive water consumption, and release toxic and eutrophicating chemicals. other ecologists have defined the extensive global network of road systems as a type of technoecosystem. = = = technoecotypes = = = " bio - agro - and techno - ecotopes are spatially integrated in larger, regional landscape units, but they are not structurally and functionally integrated in the ecosphere. because of the adverse impacts of the latter and the great human pressures on bio - ecotopes, they are even antagonistically related and therefore cannot function together as a coherent, sustainable ecological system. " : 136 = = = technosols = = = technosols are a new form of ground group in the world reference base for soil resources ( wrb ). technosols are " mainly characterised by anthropogenic parent material of organic and mineral nature and which origin can be either natural or technogenic. " : 537 = = = technodiversity = = = technodiversity refers to the varied diversity of technological artifacts that exist in technoecosystems. = = references = =
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borgs are large ( up to ~ 1 mbp ) extrachromosomal linear dna elements found in methanotrophic archaea ( specifically methanoperedens spp. ) that live in oxygen - starved environments such as deep mud. they have been found in organisms isolated from wetland, aquifer, and riverbed environments, as well as a deserted mercury mine, in california and colorado. they were first described by basem al - shayeb and jill banfield in 2022. the nature of borgs remains unclear ; they are thought to be " giant linear plasmids " or giant viruses. at least 19 different types have been identified, all of which co - occur within methanoperedens, which shares many of their genes. methanoperedens'main chromosome is only about three times larger than the borgs it hosts. it is speculated that borgs may augment methanoperedens'capacity for anaerobic oxidation of methane and protein production. = = discovery = = borgs were discovered on march 8, 2020 by jill banfield and her research group at the university of california, berkeley. the name " borg " was chosen as a reference to the star trek faction of the same name, due to the novel genetic elements'apparent propensity to assimilate genes from microbes, most notably methanoperedens ; the name was originally suggested by banfield's son. = = features = = the structures of borg genomes are conserved and distinct from the plasmids and chromosomes of methanoperedens, as well as other archaeal genomes. borgs do not contain protein - coding genes that are associated with plasmids or viruses ; they also lack rrna genes, origins of replication, or other vital genes and features that are commonly found within minichromosomes ( also known as megaplasmids ) found in archaea. borgs range from 0. 66 - 0. 92 mbp in length, larger than the genomes of any known archaeal viruses. the sizes of borg genomes are more characteristic of eukaryote - specific double - stranded dna viruses from the phylum nucleocytoviricota, also known as nucleocytoplasmic large dna viruses ( ncldv ), which can surpass 2. 5 mbp. tandem direct repeat sequences are prevalent throughout borg genomes, and they are terminated by inverted repeats. this differs from the
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as nucleocytoplasmic large dna viruses ( ncldv ), which can surpass 2. 5 mbp. tandem direct repeat sequences are prevalent throughout borg genomes, and they are terminated by inverted repeats. this differs from the megaplasmids of some bacteria, which carry interspaced repeats and usually are not responsible for encoding necessary genes. below is a list of genes known to be encoded by borgs ( note that not every borg subtype contains the same genes ) : mobile or transposable element defense systems genes involved with the anaerobic oxidation of methane ( aom ) type iii - a crispr - cas system ( no spacer acquisition machinery, primarily targets rna ) rpl11 ( ribosomal protein l11 ) glycosyltransferase genes involved in dna and rna manipulation transport genes genes involved in energy metabolism genes encoding cell surface proteins pega s - layer genes encoding membrane - associated proteins ( unknown function, possibly affects host's membrane properties ) nifhdk operon ( involved in nitrogen fixation ) genes involved in polyhydroxyalkanoate synthesis ( carbon storage ; possibly used for when resources are low ) genes encoding tellurium resistance proteins ftsz ( tubulin homolog, involved in bactrial cell division ) major vault protein homologs tca cycle genes citrate synthase aconitase cfbb and cfbc coenzyme f420 : l - glutamate ligase - cofe electron bifurcating complexes d - lactate dehydrogenase genes involved in tetrahydromethanopterin synthesis genes encoding ferredoxin proteins genes encoding 5, 6, 7, 8 - tetrahydromethanopterin hydro - lyase ( fae ) ( involved in formaldehyde detoxification ) genes encoding carbon monoxide dehydrogenase ( codh ) genes encoding plastocyanin genes encoding cupredoxins genes encoding multiheme cytochromes ( mhc ) = = references = =
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dissolved load is the portion of a stream's total sediment load that is carried in solution, especially ions from chemical weathering. it is a major contributor to the total amount of material removed from a river's drainage basin, along with suspended load and bed load. the amount of material carried as dissolved load is typically much smaller than the suspended load, though this is not always the case, particularly when the available river flow is mostly harnessed for purposes such as irrigation or industrial uses. dissolved load comprises a significant portion of the total material flux out of a landscape, and its composition is important in regulating the chemistry and biology of the stream water. the dissolved load is primarily controlled by the rate of chemical weathering, which depends on climate and weather conditions such as moisture and temperature. dissolved load has many useful applications within the field of geology, including erosion, denudation, and reconstructing climate in the past. = = measurement techniques = = dissolved load is typically measured by taking samples of water from a river and running various scientific tests on them. first, the ph, conductivity, and bicarbonate alkalinity of the sample are measured. next, samples are filtered to remove any suspended sediments and preserved with chloroform to prevent growth of microorganisms, while the others are acidified with hydrochloric acid added to keep dissolved ions from precipitating out of solution. then, various chemical tests are applied to determine the concentration of each solute. for example, the concentrations of sodium and potassium ions can be determined by flame photometry, while the calcium and magnesium ion concentrations can be determined by atomic absorption spectrophotometry. = = applications = = = = = reconstructing climate = = = dissolved load can provide valuable information about the rate of soil formation and other processes of chemical erosion. in particular, the mass balance between the dissolved load and solid phase is helpful in determining surface dynamics. in addition, dissolved load can be used to reconstruct the climate of the earth in the past. this is because chemical weathering is the major contributor to the dissolved load of a stream. the chemical weathering of silicate rocks is the primary sink for carbon dioxide in the atmosphere, because atmospheric carbon dioxide is converted into carbonate rocks in the carbonate β silicate cycle. carbon dioxide concentrations are the primary control of the greenhouse effect, which determines the temperature of the earth. = = = denudation = = = denudation is the process of wearing away the top layers
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in the carbonate β silicate cycle. carbon dioxide concentrations are the primary control of the greenhouse effect, which determines the temperature of the earth. = = = denudation = = = denudation is the process of wearing away the top layers of earth's landscape. because the denudation rate is normally too low to measure directly, it can be indirectly determined by measuring the sediment load of the streams that drain the area in question. this is possible because any material that passes through a certain point on a stream is guaranteed to have come from somewhere in the stream's drainage basin upstream of that point. as topographic relief increases, the dissolved load's contribution to the total stream load decreases because on steeper surfaces, rain is less likely to infiltrate the rocks, leading to less chemical weathering, which decreases the dissolved load. = = = salt export = = = the process of carrying salts by water to the sea or a land - locked lake from a river basin is called salt export. when adequate salt export is not occurring, the river basin area gradually converts into saline soils and / or alkali soils, particularly in lower reaches. = = dissolved loads of selected major rivers = = = = see also = = = = references = = usgs cmg infobank : suspended and dissolved loads
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in fields like computational chemistry and solid - state and condensed matter physics the so - called atomic orbitals, or spin - orbitals, as they appear in textbooks on quantum physics, are often partially replaced by cubic harmonics for a number of reasons. these harmonics are usually named tesseral harmonics in the field of condensed matter physics in which the name kubic harmonics rather refers to the irreducible representations in the cubic point - group. = = introduction = = the 2 l + 1 { \ displaystyle 2l + 1 } hydrogen - like atomic orbitals with principal quantum number n { \ displaystyle n } and angular momentum quantum number l { \ displaystyle l } are often expressed as Ο n l m ( r ) = r n l ( r ) y l m ( ΞΈ, Ο ) { \ displaystyle \ psi _ { nlm } ( \ mathbf { r } ) = r _ { nl } ( r ) y _ { l } ^ { m } ( \ theta, \ varphi ) } in which the r n l ( r ) { \ displaystyle r _ { nl } ( r ) } is the radial part of the wave function and y l m ( ΞΈ, Ο ) { \ displaystyle y _ { l } ^ { m } ( \ theta, \ varphi ) } is the angular dependent part. the y l m ( ΞΈ, Ο ) { \ displaystyle y _ { l } ^ { m } ( \ theta, \ varphi ) } are the spherical harmonics, which are solutions of the angular momentum operator. the spherical harmonics are representations of functions of the full rotation group so ( 3 ) with rotational symmetry. in many fields of physics and chemistry these spherical harmonics are replaced by cubic harmonics because the rotational symmetry of the atom and its environment are distorted or because cubic harmonics offer computational benefits. = = symmetry and coordinate system = = in many cases, especially in chemistry and solid - state and condensed - matter physics, the system under investigation doesn't have rotational symmetry. often it has some kind of lower symmetry, with a special point group representation, or it has no spatial symmetry at all. biological and biochemical systems, like amino acids and enzymes often belong to low molecular symmetry point groups. the solid crystals of the elements often belong to the space groups and point groups with high symmetry. ( cubic harmonics representations are often listed and referenced in point group tables. ) the system has at least a fixed orientation in three - dimensional euclidean
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groups. the solid crystals of the elements often belong to the space groups and point groups with high symmetry. ( cubic harmonics representations are often listed and referenced in point group tables. ) the system has at least a fixed orientation in three - dimensional euclidean space. therefore, the coordinate system that is used in such cases is most often a cartesian coordinate system instead of a spherical coordinate system. in a cartesian coordinate system the atomic orbitals are often expressed as Ο n l c ( r ) = r n l ( r ) x l c ( r ) { \ displaystyle \ psi _ { nlc } ( \ mathbf { r } ) = r _ { nl } ( r ) x _ { lc } ( \ mathbf { r } ) } with the cubic harmonics, x l c ( r ) { \ displaystyle x _ { lc } ( \ mathbf { r } ) }, as a basis set. lcao and mo calculations in computational chemistry or tight binding calculations in solid - state physics use cubic harmonics as an atomic orbital basis. the indices lc are denoting some kind of cartesian representation. = = basis transformations = = for the representations of the spherical harmonics a spherical coordinate system is chosen with a principal axis in the z - direction. for the cubic harmonics this axis is also the most convenient choice. for states of higher angular momentum quantum number l { \ displaystyle l } and a higher dimension of l ( l + 1 ) { \ displaystyle l ( l + 1 ) } the number of possible rotations or basis transformations in hilbert space grows and so does the number of possible orthogonal representations that can be constructed on the basis of the l ( l + 1 ) { \ displaystyle l ( l + 1 ) } - dimensional spherical harmonics basis set. there is more freedom to choose a representation that fits the point group symmetry of the problem. the cubic representations that are listed in the table are a result of the transformations, which are 45Β° 2d rotations and a 90Β° rotation to the real axis if necessary, like x l c ( r ) = y l 0 { \ displaystyle x _ { lc } ( \ mathbf { r } ) = y _ { l } ^ { 0 } } x l c β² ( r ) = 1 i n c β² 2 ( y l m β y l β m ) { \ displaystyle x _ { lc'} ( \ mathbf { r } ) = { \ frac { 1 } { i ^
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β² ( r ) = 1 i n c β² 2 ( y l m β y l β m ) { \ displaystyle x _ { lc'} ( \ mathbf { r } ) = { \ frac { 1 } { i ^ { n _ { c'} } { \ sqrt { 2 } } } } \ left ( y _ { l } ^ { m } - y _ { l } ^ { - m } \ right ) } x l c β³ ( r ) = 1 i n c β³ 2 ( y l m + y l β m ) { \ displaystyle x _ { lc'' } ( \ mathbf { r } ) = { \ frac { 1 } { i ^ { n _ { c'' } } { \ sqrt { 2 } } } } \ left ( y _ { l } ^ { m } + y _ { l } ^ { - m } \ right ) } a substantial number of the spherical harmonics are listed in the table of spherical harmonics. = = computational benefits = = first of all, the cubic harmonics are real functions, while spherical harmonics are complex functions. the complex numbers are two - dimensional with a real part and an imaginary part. complex numbers offer very handsome and effective tools to tackle mathematical problems analytically but they are not very effective when they are used for numerical calculations. skipping the imaginary part saves half the calculational effort in summations, a factor of four in multiplications and often factors of eight or even more when it comes to computations involving matrices. the cubic harmonics often fit the symmetry of the potential or surrounding of an atom. a common surrounding of atoms in solids and chemical complexes is an octahedral surrounding with an octahedral cubic point group symmetry. the representations of the cubic harmonics often have a high symmetry and multiplicity so operations like integrations can be reduced to a limited, or irreducible, part of the domain of the function that has to be evaluated. a problem with the 48 - fold octahedral oh symmetry can be calculated much faster if one limits a calculation, like an integration, to the irreducible part of the domain of the function. = = table of cubic harmonics = = = = = the s - orbitals = = = the s - orbitals only have a radial part. Ο n 00 ( r ) = r n 0 ( r ) y 0 0 { \ displaystyle \ psi _ { n00 } (
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= = = the s - orbitals = = = the s - orbitals only have a radial part. Ο n 00 ( r ) = r n 0 ( r ) y 0 0 { \ displaystyle \ psi _ { n00 } ( \ mathbf { r } ) = r _ { n0 } ( r ) y _ { 0 } ^ { 0 } } s = x 00 = y 0 0 = 1 4 Ο { \ displaystyle s = x _ { 00 } = y _ { 0 } ^ { 0 } = { \ frac { 1 } { \ sqrt { 4 \ pi } } } } = = = the p - orbitals = = = the three p - orbitals are atomic orbitals with an angular momentum quantum number β = 1. the cubic harmonic expression of the p - orbitals p z = n 1 c z r = y 1 0 { \ displaystyle p _ { z } = n _ { 1 } ^ { c } { \ frac { z } { r } } = y _ { 1 } ^ { 0 } } p x = n 1 c x r = 1 2 ( y 1 β 1 β y 1 1 ) { \ displaystyle p _ { x } = n _ { 1 } ^ { c } { \ frac { x } { r } } = { \ frac { 1 } { \ sqrt { 2 } } } \ left ( y _ { 1 } ^ { - 1 } - y _ { 1 } ^ { 1 } \ right ) } p y = n 1 c y r = i 2 ( y 1 β 1 + y 1 1 ) { \ displaystyle p _ { y } = n _ { 1 } ^ { c } { \ frac { y } { r } } = { \ frac { i } { \ sqrt { 2 } } } \ left ( y _ { 1 } ^ { - 1 } + y _ { 1 } ^ { 1 } \ right ) } with n 1 c = ( 3 4 Ο ) 1 / 2 { \ displaystyle n _ { 1 } ^ { c } = \ left ( { \ frac { 3 } { 4 \ pi } } \ right ) ^ { 1 / 2 } } = = = the d - orbitals = = = the five d - orbitals are atomic orbitals with an angular momentum quantum number β = 2. the angular part of the d - orbitals are often expressed like Ο
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1 / 2 } } = = = the d - orbitals = = = the five d - orbitals are atomic orbitals with an angular momentum quantum number β = 2. the angular part of the d - orbitals are often expressed like Ο n 2 c ( r ) = r n 2 ( r ) x 2 c ( r ) { \ displaystyle \ psi _ { n2c } ( \ mathbf { r } ) = r _ { n2 } ( r ) x _ { 2c } ( \ mathbf { r } ) } the angular part of the d - orbitals are the cubic harmonics x 2 c ( r ) { \ displaystyle x _ { 2c } ( \ mathbf { r } ) } d z 2 = n 2 c 3 z 2 β r 2 2 r 2 3 = y 2 0 { \ displaystyle d _ { z ^ { 2 } } = n _ { 2 } ^ { c } { \ frac { 3z ^ { 2 } - r ^ { 2 } } { 2r ^ { 2 } { \ sqrt { 3 } } } } = y _ { 2 } ^ { 0 } } d x z = n 2 c x z r 2 = 1 2 ( y 2 β 1 β y 2 1 ) { \ displaystyle d _ { xz } = n _ { 2 } ^ { c } { \ frac { xz } { r ^ { 2 } } } = { \ frac { 1 } { \ sqrt { 2 } } } \ left ( y _ { 2 } ^ { - 1 } - y _ { 2 } ^ { 1 } \ right ) } d y z = n 2 c y z r 2 = i 2 ( y 2 β 1 + y 2 1 ) { \ displaystyle d _ { yz } = n _ { 2 } ^ { c } { \ frac { yz } { r ^ { 2 } } } = { \ frac { i } { \ sqrt { 2 } } } \ left ( y _ { 2 } ^ { - 1 } + y _ { 2 } ^ { 1 } \ right ) } d x y = n 2 c x y r 2 = i 2 ( y 2 β 2 β y 2 2 ) { \ displaystyle d _ { xy } = n _ { 2 } ^ { c } { \ frac { xy } { r ^ { 2 } } } =
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= i 2 ( y 2 β 2 β y 2 2 ) { \ displaystyle d _ { xy } = n _ { 2 } ^ { c } { \ frac { xy } { r ^ { 2 } } } = { \ frac { i } { \ sqrt { 2 } } } \ left ( y _ { 2 } ^ { - 2 } - y _ { 2 } ^ { 2 } \ right ) } d x 2 β y 2 = n 2 c x 2 β y 2 2 r 2 = 1 2 ( y 2 β 2 + y 2 2 ) { \ displaystyle d _ { x ^ { 2 } - y ^ { 2 } } = n _ { 2 } ^ { c } { \ frac { x ^ { 2 } - y ^ { 2 } } { 2r ^ { 2 } } } = { \ frac { 1 } { \ sqrt { 2 } } } \ left ( y _ { 2 } ^ { - 2 } + y _ { 2 } ^ { 2 } \ right ) } with n 2 c = ( 15 4 Ο ) 1 / 2 { \ displaystyle n _ { 2 } ^ { c } = \ left ( { \ frac { 15 } { 4 \ pi } } \ right ) ^ { 1 / 2 } } = = = the f - orbitals = = = the seven f - orbitals are atomic orbitals with an angular momentum quantum number β = 3. often expressed like Ο n 3 c ( r ) = r n 3 ( r ) x 3 c ( r ) { \ displaystyle \ psi _ { n3c } ( \ mathbf { r } ) = r _ { n3 } ( r ) x _ { 3c } ( \ mathbf { r } ) } the angular part of the f - orbitals are the cubic harmonics x 3 c ( r ) { \ displaystyle x _ { 3c } ( \ mathbf { r } ) }. in many cases different linear combinations of spherical harmonics are chosen to construct a cubic f - orbital basis set. f z 3 = n 3 c z ( 2 z 2 β 3 x 2 β 3 y 2 ) 2 r 3 15 = y 3 0 { \ displaystyle f _ { z ^ { 3 } } = n _ { 3 } ^ { c } { \ frac { z ( 2z ^ { 2 } - 3x ^ { 2 } - 3y
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= y 3 0 { \ displaystyle f _ { z ^ { 3 } } = n _ { 3 } ^ { c } { \ frac { z ( 2z ^ { 2 } - 3x ^ { 2 } - 3y ^ { 2 } ) } { 2r ^ { 3 } { \ sqrt { 15 } } } } = y _ { 3 } ^ { 0 } } f x z 2 = n 3 c x ( 4 z 2 β x 2 β y 2 ) 2 r 3 10 = 1 2 ( y 3 β 1 β y 3 1 ) { \ displaystyle f _ { xz ^ { 2 } } = n _ { 3 } ^ { c } { \ frac { x ( 4z ^ { 2 } - x ^ { 2 } - y ^ { 2 } ) } { 2r ^ { 3 } { \ sqrt { 10 } } } } = { \ frac { 1 } { \ sqrt { 2 } } } \ left ( y _ { 3 } ^ { - 1 } - y _ { 3 } ^ { 1 } \ right ) } f y z 2 = n 3 c y ( 4 z 2 β x 2 β y 2 ) 2 r 3 10 = i 2 ( y 3 β 1 + y 3 1 ) { \ displaystyle f _ { yz ^ { 2 } } = n _ { 3 } ^ { c } { \ frac { y ( 4z ^ { 2 } - x ^ { 2 } - y ^ { 2 } ) } { 2r ^ { 3 } { \ sqrt { 10 } } } } = { \ frac { i } { \ sqrt { 2 } } } \ left ( y _ { 3 } ^ { - 1 } + y _ { 3 } ^ { 1 } \ right ) } f x y z = n 3 c x y z r 3 = i 2 ( y 3 β 2 β y 3 2 ) { \ displaystyle f _ { xyz } = n _ { 3 } ^ { c } { \ frac { xyz } { r ^ { 3 } } } = { \ frac { i } { \ sqrt { 2 } } } \ left ( y _ { 3 } ^ { - 2 } - y _ { 3 } ^ { 2 } \ right ) } f z ( x 2 β y 2 ) = n 3 c z ( x 2 β y 2 ) 2
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} \ left ( y _ { 3 } ^ { - 2 } - y _ { 3 } ^ { 2 } \ right ) } f z ( x 2 β y 2 ) = n 3 c z ( x 2 β y 2 ) 2 r 3 = 1 2 ( y 3 β 2 + y 3 2 ) { \ displaystyle f _ { z ( x ^ { 2 } - y ^ { 2 } ) } = n _ { 3 } ^ { c } { \ frac { z \ left ( x ^ { 2 } - y ^ { 2 } \ right ) } { 2r ^ { 3 } } } = { \ frac { 1 } { \ sqrt { 2 } } } \ left ( y _ { 3 } ^ { - 2 } + y _ { 3 } ^ { 2 } \ right ) } f x ( x 2 β 3 y 2 ) = n 3 c x ( x 2 β 3 y 2 ) 2 r 3 6 = 1 2 ( y 3 β 3 β y 3 3 ) { \ displaystyle f _ { x ( x ^ { 2 } - 3y ^ { 2 } ) } = n _ { 3 } ^ { c } { \ frac { x \ left ( x ^ { 2 } - 3y ^ { 2 } \ right ) } { 2r ^ { 3 } { \ sqrt { 6 } } } } = { \ frac { 1 } { \ sqrt { 2 } } } \ left ( y _ { 3 } ^ { - 3 } - y _ { 3 } ^ { 3 } \ right ) } f y ( 3 x 2 β y 2 ) = n 3 c y ( 3 x 2 β y 2 ) 2 r 3 6 = i 2 ( y 3 β 3 + y 3 3 ) { \ displaystyle f _ { y ( 3x ^ { 2 } - y ^ { 2 } ) } = n _ { 3 } ^ { c } { \ frac { y \ left ( 3x ^ { 2 } - y ^ { 2 } \ right ) } { 2r ^ { 3 } { \ sqrt { 6 } } } } = { \ frac { i } { \ sqrt { 2 } } } \ left ( y _ { 3 } ^ { - 3 } + y _ { 3 } ^ { 3 } \ right ) } with n 3 c = ( 105 4 Ο ) 1 / 2 { \ displaystyle n _ {
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} } } \ left ( y _ { 3 } ^ { - 3 } + y _ { 3 } ^ { 3 } \ right ) } with n 3 c = ( 105 4 Ο ) 1 / 2 { \ displaystyle n _ { 3 } ^ { c } = \ left ( { \ frac { 105 } { 4 \ pi } } \ right ) ^ { 1 / 2 } } = = see also = = = = references = =
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knowledge interchange format ( kif ) is a computer language designed to enable systems to share and re - use information from knowledge - based systems. kif is similar to frame languages such as kl - one and loom but unlike such language its primary role is not intended as a framework for the expression or use of knowledge but rather for the interchange of knowledge between systems. the designers of kif likened it to postscript. postscript was not designed primarily as a language to store and manipulate documents but rather as an interchange format for systems and devices to share documents. in the same way kif is meant to facilitate sharing of knowledge across different systems that use different languages, formalisms, platforms, etc. kif has a declarative semantics. it is meant to describe facts about the world rather than processes or procedures. knowledge can be described as objects, functions, relations, and rules. it is a formal language, i. e., it can express arbitrary statements in first order logic and can support reasoners that can prove the consistency of a set of kif statements. kif also supports non - monotonic reasoning. kif was created by michael genesereth, richard fikes and others participating in the darpa knowledge sharing effort. although the original kif group intended to submit to a formal standards body, that did not occur. a later version called common logic has since been developed for submission to iso and has been approved and published. a variant called suo - kif is the language in which the suggested upper merged ontology is written. a practical application of the knowledge interchange format is an agent communication language in a multi - agent system. = = see also = = knowledge query and manipulation language = = references = = = = external links = = knowledge interchange format page at the stanford ai lab common logic
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industrial and organizational psychology ( i - o psychology ) " focuses the lens of psychological science on a key aspect of human life, namely, their work lives. in general, the goals of i - o psychology are to better understand and optimize the effectiveness, health, and well - being of both individuals and organizations. " it is an applied discipline within psychology and is an international profession. i - o psychology is also known as occupational psychology in the united kingdom, organisational psychology in australia, south africa and new zealand, and work and organizational ( wo ) psychology throughout europe and brazil. industrial, work, and organizational ( iwo ) psychology is the broader, more global term for the science and profession. i - o psychologists are trained in the scientist β practitioner model. as an applied psychology field, the discipline involves both research and practice and i - o psychologists apply psychological theories and principles to organizations and the individuals within them. they contribute to an organization's success by improving the job performance, wellbeing, motivation, job satisfaction and the health and safety of employees. an i - o psychologist conducts research on employee attitudes, behaviors, emotions, motivation, and stress. the field is concerned with how these things can be improved through recruitment processes, training and development programs, 360 - degree feedback, change management, and other management systems and other interventions. i - o psychology research and practice also includes the work β nonwork interface such as selecting and transitioning into a new career, occupational burnout, unemployment, retirement, and work β family conflict and balance. i - o psychology is one of the 17 recognized professional specialties by the american psychological association ( apa ). in the united states the profession is represented by division 14 of the apa and is formally known as the society for industrial and organizational psychology ( siop ). similar i - o psychology societies can be found in many countries. in 2009 the alliance for organizational psychology was formed and is a federation of work, industrial, & organizational psychology societies and " network partners " from around the world. = = international = = i - o psychology is an international science and profession and depending on the region of the world, it is referred to by different titles. in north america, canada and south africa the title " i - o " psychology is used ; in the united kingdom, the field is known as occupational psychology. occupational psychology in the uk is one of nine " protected titles " within the " practitioner psychologist " professions. the profession is regulated by the health and care professions council.
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psychology is used ; in the united kingdom, the field is known as occupational psychology. occupational psychology in the uk is one of nine " protected titles " within the " practitioner psychologist " professions. the profession is regulated by the health and care professions council. in the uk, graduate programs in psychology, including occupational psychology, are accredited by the british psychological society. in europe, someone with a specialist europsy certificate in work and organisational psychology is a fully qualified psychologist and a specialist in the work psychology field. industrial and organizational psychologists reaching the europsy standard are recorded in the register of european psychologists. i - o psychology is one of the three main psychology specializations in europe. in australia, the title " organisational psychologist " is protected by law and regulated by the australian health practitioner regulation agency ( ahpra ). organizational psychology is one of nine areas of specialist endorsement for psychology practice in australia. in south africa, industrial psychology is a registration category for the profession of psychologist as regulated by the health professions council of south africa ( hpcsa ). in 2009 the alliance for organizational psychology was formed and is a federation of work, industrial, & organizational psychology societies and " network partners " from around the world. in 2021 the british psychological society ( bps ) division of occupational psychology ( dop ) and the australian psychological society's ( aps ) college of organizational psychology joined the alliance. the alliance currently has member organizations representing industrial, work and organisational psychology and iwo psychologists from australia, britain, brazil, canada, chile, europe, germany, hong kong, japan, netherlands, new zealand, singapore, south africa and the united states. = = historical overview = = the historical development of i - o psychology was paralleled in the us, the uk, australia, germany, the netherlands, and eastern european countries such as romania. the roots of i - o psychology trace back to almost the beginning of psychology as a science, when wilhelm wundt founded one of the first psychological laboratories in 1879 in leipzig, germany. in the mid β 1880s, wundt trained two psychologists, hugo munsterberg and james mckeen cattell, who went on to have a major influence on the emergence of i - o psychology. world war i was an impetus for the development of the field simultaneously in the uk and us. hugo munsterberg, one of the founders of i - o psychology, wrote, " our aim is to sketch the outlines of a new science which is intermediate between the modern laboratory psychology and the problems of economics : the psychological experiment
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the uk and us. hugo munsterberg, one of the founders of i - o psychology, wrote, " our aim is to sketch the outlines of a new science which is intermediate between the modern laboratory psychology and the problems of economics : the psychological experiment is systematically to be placed at the service of commerce and industry " ( p. 3 ). instead of viewing performance differences as human " errors, " cattell was one of the first to recognize the importance of differences among individuals as a way of better understanding work behavior. walter dill scott, who was a contemporary of cattell and was elected president of the american psychological association ( apa ) in 1919, was arguably the most prominent i - o psychologist of his time. scott, along with walter van dyke bingham, worked at what was then carnegie institute of technology ( now carnegie mellon university ), developing methods for selecting and training sales personnel. the " industrial " side of i - o psychology originated in research on individual differences, assessment, and the prediction of work performance. industrial psychology crystallized during world war i, in response to the need to rapidly assign new troops to duty. scott and bingham volunteered to help with the testing and placement of more than a million u. s. army recruits. in 1917, together with other prominent psychologists, they adapted the well - known intelligence test the stanford β binet, which was designed for testing one individual at a time, to make it suitable for group testing. the new test was called the army alpha. after the war, increasing employment in the u. s. created opportunities for i - o psychology practitioners who called themselves " industrial psychologists " the " organizational " side of the field was focused on employee behavior, feelings, and well - being. during world war i, with the u. k. government's interest in worker productivity in munitions factories, charles myers studied worker fatigue and well - being. following the war, elton mayo found that rest periods improved morale and reduced turnover in a philadelphia textile factory. he later joined the ongoing hawthorne studies, where he became interested in how workers'emotions and informal relationships affected productivity. the results of these studies ushered in the human relations movement. world war ii brought renewed interest in ability testing. the u. s. military needed to accurately place recruits in new technologically advanced jobs. there was also concern with morale and fatigue in war - industry workers. in the 1960s arthur kornhauser examined the impact on productivity of hiring mentally unstable workers. kornhauser also examined the link between industrial working conditions and worker
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advanced jobs. there was also concern with morale and fatigue in war - industry workers. in the 1960s arthur kornhauser examined the impact on productivity of hiring mentally unstable workers. kornhauser also examined the link between industrial working conditions and worker mental health as well as the spillover into a worker's personal life of having an unsatisfying job. zickar noted that most of kornhauser's i - o contemporaries favored management and kornhauser was largely alone in his interest in protecting workers. vinchur and koppes ( 2010 ) observed that i - o psychologists'interest in job stress is a relatively recent development ( p. 22 ). the industrial psychology division of the former american association of applied psychology became a division within apa, becoming division 14 of apa. it was initially called the industrial and business psychology division. in 1962, the name was changed to the industrial psychology division. in 1973, it was renamed again, this time to the division of industrial and organizational psychology. in 1982, the unit become more independent of apa, and its name was changed again, this time to the society for industrial and organizational psychology. the name change of the division from " industrial psychology " to " industrial and organizational psychology " reflected the shift in the work of industrial psychologists who had originally addressed work behavior from the individual perspective, examining performance and attitudes of individual workers. their work became broader. group behavior in the workplace became a worthy subject of study. the emphasis on the " organizational " underlined the fact that when an individual joins an organization ( e. g., the organization that hired them ), they will be exposed to a common goal and a common set of operating procedures. in the 1970s in the uk, references to occupational psychology became more common than references to i - o psychology. according to bryan and vinchur, " while organizational psychology increased in popularity through [ the 1960s and 1970s ], research and practice in the traditional areas of industrial psychology continued, primarily driven by employment legislation and case law ". p. 53 there was a focus on fairness and validity in selection efforts as well as in the job analyses that undergirded selection instruments. for example, i - o psychology showed increased interest in behaviorally anchored rating scales. what critics there were of i - o psychology accused the discipline of being responsive only to the concerns of management. from the 1980s to 2010s, other developments in i - o psychology took place. researchers increasingly adopted a multi - level approach, attempting to understand
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what critics there were of i - o psychology accused the discipline of being responsive only to the concerns of management. from the 1980s to 2010s, other developments in i - o psychology took place. researchers increasingly adopted a multi - level approach, attempting to understand behavioral phenomena from both the level of the organization and the level of the individual worker. there was also an increased interest in the needs and expectations of employees as individuals. for example, an emphasis on organizational justice and the psychological contract took root, as well as the more traditional concerns of selection and training. methodological innovations ( e. g., meta - analyses, structural equation modeling ) were adopted. with the passage of the american with disabilities act in 1990 and parallel legislation elsewhere in the world, i - o psychology saw an increased emphasis on " fairness in personnel decisions. " training research relied increasingly on advances in educational psychology and cognitive science. = = research methods = = i - o researchers employ both qualitative and quantitative methods, although quantitative methods are far more common. basic quantitative methods used in i - o psychology include correlation, multiple regression, and analysis of variance. more advanced statistical methods include logistic regression, structural equation modeling, and hierarchical linear modeling ( hlm ; also known as multilevel modeling ). i - o researchers have also employed meta - analysis. i - o psychologists also employ psychometric methods including methods associated with classical test theory, generalizability theory, and item response theory ( irt ). i - o psychologists have also employed qualitative methods, which largely involve focus groups, interviews, and case studies. i - o psychologists conducting research on organizational culture have employed ethnographic techniques and participant observation. a qualitative technique associated with i - o psychology is flanagan's critical incident technique. i - o psychologists have also coordinated the use of quantitative and qualitative methods in the same study, = = topics = = i - o psychologists deal with a wide range of topics concerning people in the workplace. = = = job analysis = = = job analysis encompasses a number of different methods including, but not limited to, interviews, questionnaires, task analysis, and observation. a job analysis primarily involves the systematic collection of information about a job. a task - oriented job analysis involves an assessment of the duties, tasks, and / or competencies a job requires. by contrast, a worker - oriented job analysis involves an examination of the knowledge, skills, abilities, and other characteristics ( ksaos ) required to successfully perform the work. information obtained
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duties, tasks, and / or competencies a job requires. by contrast, a worker - oriented job analysis involves an examination of the knowledge, skills, abilities, and other characteristics ( ksaos ) required to successfully perform the work. information obtained from job analyses are used for many purposes, including the creation of job - relevant selection procedures, the development of criteria for performance appraisals, the conducting of performance appraisals, and the development and implementation of training programs. = = = personnel recruitment and selection = = = i - o psychologists design ( a ) recruitment processes and ( b ) personnel selection systems. personnel recruitment is the process of identifying qualified candidates in the workforce and getting them to apply for jobs within an organization. personnel recruitment processes include developing job announcements, placing ads, defining key qualifications for applicants, and screening out unqualified applicants. personnel selection is the systematic process of hiring and promoting personnel. personnel selection systems employing i - o psychology methods use quantitative data to determine the most qualified candidates. this can involve the use of psychological tests, biographical information blanks, interviews, work samples, and assessment centers. personnel selection procedures are usually validated, i. e., shown to be job relevant to personnel selection, using one or more of the following types of validity : content validity, construct validity, and / or criterion - related validity. i - o psychologists must adhere to professional standards in personnel selection efforts. siop ( e. g., principles for validation and use of personnel selection procedures ) and apa together with the national council on measurement in education ( e. g., standards for educational and psychological testing are sources of those standards. the equal employment opportunity commission's uniform guidelines are also influential in guiding personnel selection decisions. a meta - analysis of selection methods found that general mental ability ( g factor ) was the best overall predictor of job performance and attainment in training. = = = performance appraisal / management = = = performance appraisal or performance evaluation is the process in which an individual's or a group's work behaviors and outcomes are assessed against managers'and others'expectations for the job. performance appraisal is used for a variety of purposes including alignment with organizational objectives, the basis for employment decisions ( promotion, raises and termination ), feedback to employees, and training needs assessment. performance management is the process of providing performance feedback relative to expectations and information relevant to helping a worker improve their performance ( e. g., coaching, mentoring ). performance management may also
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and termination ), feedback to employees, and training needs assessment. performance management is the process of providing performance feedback relative to expectations and information relevant to helping a worker improve their performance ( e. g., coaching, mentoring ). performance management may also include documenting and tracking performance information for organizational evaluation purposes. = = = individual assessment and psychometrics = = = individual assessment involves the measurement of individual differences. i - o psychologists perform individual assessments in order to evaluate differences among candidates for employment as well as differences among employees. the constructs measured pertain to job performance. with candidates for employment, individual assessment is often part of the personnel selection process. these assessments can include written tests, aptitude tests, physical tests, psycho - motor tests, personality tests, integrity and reliability tests, work samples, simulations, and assessment centres. = = = occupational health, safety and well - being = = = a more recent focus of i - o field is the health, safety, and well - being of employees. topics include occupational safety, occupational stress, and workplace bullying, aggression and violence. = = = = occupational stress = = = = there are many features of work that can be stressful to employees. research has identified a number of job stressors ( environmental conditions at work ) that contribute to strains ( adverse behavioral, emotional, physical, and psychological reactions ). occupational stress can have implications for organizational performance because of the emotions job stress evokes. for example, a job stressor such as conflict with a supervisor can precipitate anger that in turn motivates counterproductive workplace behaviors. a number of prominent models of job stress have been developed to explain the job stress process, including the person - environment ( p - e ) fit model, which was developed by university of michigan social psychologists, and the demand - control ( - support ) and effort - reward imbalance models, which were developed by sociologists. research has also examined occupational stress in specific occupations, including police, general practitioners, and dentists. another concern has been the relation of occupational stress to family life. other i - o researchers have examined gender differences in leadership style and job stress and strain in the context of male - and female - dominated industries, and unemployment - related distress. occupational stress has also been linked to lack of fit between people and their jobs. = = = = occupational safety = = = = accidents and safety in the workplace are important because of the serious injuries and fatalities that are all too common. research has linked accidents to psychosocial
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linked to lack of fit between people and their jobs. = = = = occupational safety = = = = accidents and safety in the workplace are important because of the serious injuries and fatalities that are all too common. research has linked accidents to psychosocial factors in the workplace including overwork that leads to fatigue, workplace violence, and working night shifts. " stress audits " can help organizations remain compliant with various occupational safety regulations. psychosocial hazards can affect musculoskeletal disorders. a psychosocial factor related to accident risk is safety climate, which refers to employees'perceptions of the extent to which their work organization prioritizes safety. by contrast, psychosocial safety climate refers to management's " policies, practices, and procedures " aimed at protecting workers'psychological health. research on safety leadership is also relevant to understanding employee safety performance. research suggests that safety - oriented transformational leadership is associated with a positive safety climate and safe worker practices. = = = = workplace bullying, aggression and violence = = = = i - o psychologists are concerned with the related topics of workplace bullying, aggression, and violence. for example, i - o research found that exposure to workplace violence elicited ruminative thinking. ruminative thinking is associated with poor well - being. research has found that interpersonal aggressive behaviour is associated with worse team performance. = = = = relation to occupational health psychology = = = = a new discipline, occupational health psychology ( ohp ), emerged from both health psychology and i - o psychology as well as occupational medicine. ohp concerns itself with such topic areas as the impact of occupational stressors on mental and physical health, the health impact of involuntary unemployment, violence and bullying in the workplace, psychosocial factors that influence accident risk and safety, work β family balance, and interventions designed to improve / protect worker health. spector observed that one of the problems facing i - o psychologists in the late 20th century who were interested in the health of working people was resistance within the field to publishing papers on worker health. in the 21st century, ohp topics have become popular at the society for industrial and organizational psychology conference. = = = work design = = = work design concerns the " content and organisation of one's work tasks, activities, relationships, and responsibilities. " research has demonstrated that work design has important implications for individual employees ( e. g., level of engagement, job strain, chance of injury ), teams ( e. g., how effectively teams co - or
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, relationships, and responsibilities. " research has demonstrated that work design has important implications for individual employees ( e. g., level of engagement, job strain, chance of injury ), teams ( e. g., how effectively teams co - ordinate their activities ), organisations ( e. g., productivity, safety, efficiency targets ), and society ( e. g., whether a nation utilises the skills of its population or promotes effective aging ). i - o psychologists review job tasks, relationships, and an individual's way of thinking about their work to ensure that their roles are meaningful and motivating, thus creating greater productivity and job satisfaction. deliberate interventions aimed at altering work design are sometimes referred to as work redesign. such interventions can be initiated by the management of an organization ( e. g., job rotation, job enlargement, job enrichment ) or by individual workers ( e. g., job crafting, role innovation, idiosyncratic ideals ). = = = training and training evaluation = = = training involves the systematic teaching of skills, concepts, or attitudes that results in improved performance in another environment. because many people hired for a job are not already versed in all the tasks the job requires, training may be needed to help the individual perform the job effectively. evidence indicates that training is often effective, and that it succeeds in terms of higher net sales and gross profitability per employee. similar to performance management ( see above ), an i - o psychologist would employ a job analysis in concert with the application of the principles of instructional design to create an effective training program. a training program is likely to include a summative evaluation at its conclusion in order to ensure that trainees have met the training objectives and can perform the target work tasks at an acceptable level. kirkpatrick describes four levels of criteria by which to evaluate training : reactions are the extent to which trainees enjoyed the training and found it worthwhile. learning is the knowledge and skill trainees acquired from the training. behavior is the change in behavior trainees exhibit on the job after training, for example, did they perform trained tasks more quickly? results are the effect of the change in knowledge or behavior on the job, for example, was overall productivity increased or costs decreased? training programs often include formative evaluations to assess the effect of the training as the training proceeds. formative evaluations can be used to locate problems in training procedures and help i - o psychologists make corrective adjustments while training is ongoing
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costs decreased? training programs often include formative evaluations to assess the effect of the training as the training proceeds. formative evaluations can be used to locate problems in training procedures and help i - o psychologists make corrective adjustments while training is ongoing. the foundation for training programs is learning. learning outcomes can be organized into three broad categories : cognitive, skill - based, and affective outcomes. cognitive training is aimed at instilling declarative knowledge or the knowledge of rules, facts, and principles ( e. g., police officer training covers laws and court procedures ). skill - based training aims to impart procedural knowledge ( e. g., skills needed to use a special tool ) or technical skills ( e. g., understanding the workings of software program ). affective training concerns teaching individuals to develop specific attitudes or beliefs that predispose trainees to behave a certain way ( e. g., show commitment to the organization, appreciate diversity ). a needs assessment, an analysis of corporate and individual goals, is often undertaken prior to the development of a training program. : 164 in addition, a careful training needs analysis is required in order to develop a systematic understanding of where training is needed, what should be taught, and who will be trained. a training needs analysis typically involves a three - step process that includes organizational analysis, task analysis, and person analysis. an organizational analysis is an examination of organizational goals and resources as well as the organizational environment. the results of an organizational analysis help to determine where training should be directed. the analysis identifies the training needs of different departments or subunits. it systematically assesses manager, peer, and technological support for transfer of training. an organizational analysis also takes into account the climate of the organization and its subunits. for example, if a climate for safety is emphasized throughout the organization or in subunits of the organization ( e. g., production ), then training needs will likely reflect an emphasis on safety. a task analysis uses the results of a job analysis to determine what is needed for successful job performance, contributing to training content. with organizations increasingly trying to identify " core competencies " that are required for all jobs, task analysis can also include an assessment of competencies. a person analysis identifies which individuals within an organization should receive training and what kind of instruction they need. employee needs can be assessed using a variety of methods that identify weaknesses that training can address. = = = motivation in the workplace = = = work motivation reflects the energy an individual applies " to
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organization should receive training and what kind of instruction they need. employee needs can be assessed using a variety of methods that identify weaknesses that training can address. = = = motivation in the workplace = = = work motivation reflects the energy an individual applies " to initiate work - related behavior, and to determine its form, direction, intensity, and duration " understanding what motivates an organization's employees is central to i - o psychology. motivation is generally thought of as a theoretical construct that fuels behavior. an incentive is an anticipated reward that is thought to incline a person to behave a certain way. motivation varies among individuals. studying its influence on behavior, it must be examined together with ability and environmental influences. because of motivation's role in influencing workplace behavior and performance, many organizations structure the work environment to encourage productive behaviors and discourage unproductive behaviors. motivation involves three psychological processes : arousal, direction, and intensity. arousal is what initiates action. it is often fueled by a person's need or desire for something that is missing from their life, either totally or partially. direction refers to the path employees take in accomplishing the goals they set for themselves. intensity is the amount of energy employees put into goal - directed work performance. the level of intensity often reflects the importance and difficulty of the goal. these psychological processes involve four factors. first, motivation serves to direct attention, focusing on particular issues, people, tasks, etc. second, it serves to stimulate effort. third, motivation influences persistence. finally, motivation influences the choice and application of task - related strategies. = = = organizational climate = = = organizational climate is the perceptions of employees about what is important in an organization, that is, what behaviors are encouraged versus discouraged. it can be assessed in individual employees ( climate perceptions ) or averaged across groups of employees within a department or organization ( organizational climate ). climates are usually focused on specific employee outcomes, or what is called β climate for something β. there are more than a dozen types of climates that have been assessed and studied. some of the more popular include : customer service climate : the emphasis placed on providing good service. it has been shown to relate to employee service performance. diversity climate : the extent to which organizations value differences among employees and expect employees to treat everyone with respect. it has been linked to job satisfaction. ethical climate : the extent to which organizations emphasize ethical practices. innovation climate : the extent to which organizations encourage employees to use new approaches. psychosocial safety climate : organizations with such climates emphasize the importance of
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. it has been linked to job satisfaction. ethical climate : the extent to which organizations emphasize ethical practices. innovation climate : the extent to which organizations encourage employees to use new approaches. psychosocial safety climate : organizations with such climates emphasize the importance of psychological health and well - being. safety climate : such organizations emphasize safety and have fewer accidents and injuries. climate concerns organizational policies and practices that encourage or discourage specific behaviors by employees. shared perceptions of what the organization emphasizes ( organizational climate ) is part of organizational culture. = = = organizational culture = = = while there is no universal definition for organizational culture, a collective understanding shares the following assumptions : : 2... that they are related to history and tradition, have some depth, are difficult to grasp and account for, and must be interpreted ; that they are collective and shared by members of groups and primarily ideational in character, having to do with values, understandings, beliefs, knowledge, and other intangibles ; and that they are holistic and subjective rather than strictly rational and analytical. organizational culture has been shown to affect important organizational outcomes such as performance, attraction, recruitment, retention, employee satisfaction, and employee well - being. there are three levels of organizational culture : artifacts, shared values, and basic beliefs and assumptions. artifacts comprise the physical components of the organization that relay cultural meaning. shared values are individuals'preferences regarding certain aspects of the organization's culture ( e. g., loyalty, customer service ). basic beliefs and assumptions include individuals'impressions about the trustworthiness and supportiveness of an organization, and are often deeply ingrained within the organization's culture. in addition to an overall culture, organizations also have subcultures. subcultures can be departmental ( e. g. different work units ) or defined by geographical distinction. while there is no single " type " of organizational culture, some researchers have developed models to describe different organizational cultures. = = = group behavior = = = group behavior involves the interactions among individuals in a collective. most i - o group research is about teams, which are groups in which people work together to achieve the same task goals. the individuals'opinions, attitudes, and adaptations affect group behavior, with group behavior in turn affecting those opinions, etc. the interactions are thought to fulfill some need satisfaction in an individual who is part of the collective. = = = = team effectiveness = = = = organizations often organize teams because teams can accomplish a much greater amount of work in a short period of time than an individual
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are thought to fulfill some need satisfaction in an individual who is part of the collective. = = = = team effectiveness = = = = organizations often organize teams because teams can accomplish a much greater amount of work in a short period of time than an individual can accomplish. i - o research has examined the harm workplace aggression does to team performance. = = = = team composition = = = = team composition, or the configuration of team member knowledge, skills, abilities, and other characteristics, fundamentally influences teamwork. team composition can be considered in the selection and management of teams to increase the likelihood of team success. to achieve high - quality results, teams built with members having higher skill levels are more likely to be effective than teams built around members having lesser skills ; teams that include members with a diversity of skills are also likely to show improved team performance. team members should also be compatible in terms of personality traits, values, and work styles. there is substantial evidence that personality traits and values can shape the nature of teamwork, and influence team performance. = = = = team task design = = = = a fundamental question in team task design is whether or not a task is even appropriate for a team. those tasks that require predominantly independent work are best left to individuals, and team tasks should include those tasks that consist primarily of interdependent work. when a given task is appropriate for a team, task design can play a key role in team effectiveness. job characteristic theory identifies core job dimensions that affect motivation, satisfaction, performance, etc. these dimensions include skill variety, task identity, task significance, autonomy and feedback. the dimensions map well to the team environment. individual contributors who perform team tasks that are challenging, interesting, and engaging are more likely to be motivated to exert greater effort and perform better than team members who are working on tasks that lack those characteristics. = = = = organizational resources = = = = organizational support systems affect the team effectiveness and provide resources for teams operating in the multi - team environment. during the chartering of new teams, organizational enabling resources are first identified. examples of enabling resources include facilities, equipment, information, training, and leadership. team - specific resources ( e. g., budgetary resources, human resources ) are typically made available. team - specific human resources represent the individual contributors who are selected to be team members. intra - team processes ( e. g., task design, task assignment ) involve these team - specific resources. teams also function in dynamic multi - team environments. teams often must respond
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resources represent the individual contributors who are selected to be team members. intra - team processes ( e. g., task design, task assignment ) involve these team - specific resources. teams also function in dynamic multi - team environments. teams often must respond to shifting organizational contingencies. = = = = team rewards = = = = organizational reward systems drive the strengthening and enhancing of individual team member efforts ; such efforts contribute towards reaching team goals. in other words, rewards that are given to individual team members should be contingent upon the performance of the entire team. several design elements are needed to enable organizational reward systems to operate successfully. first, for a collective assessment to be appropriate for individual team members, the group's tasks must be highly interdependent. if this is not the case, individual assessment is more appropriate than team assessment. second, individual - level reward systems and team - level reward systems must be compatible. for example, it would be unfair to reward the entire team for a job well done if only one team member did most of the work. that team member would most likely view teams and teamwork negatively, and would not want to work on a team in the future. third, an organizational culture must be created such that it supports and rewards employees who believe in the value of teamwork and who maintain a positive attitude towards team - based rewards. = = = = team goals = = = = goals potentially motivate team members when goals contain three elements : difficulty, acceptance, and specificity. under difficult goal conditions, teams with more committed members tend to outperform teams with less committed members. when team members commit to team goals, team effectiveness is a function of how supportive members are with each other. the goals of individual team members and team goals interact. team and individual goals must be coordinated. individual goals must be consistent with team goals in order for a team to be effective. = = = job satisfaction and commitment = = = job satisfaction is often thought to reflect the extent to which a worker likes their job, or individual aspects or facets of jobs. it is one of the most heavily researched topics in i - o psychology. job satisfaction has theoretical and practical utility for the field. it has been linked to important job outcomes including absenteeism, accidents, counterproductive work behavior, customer service, cyberloafing, job performance, organizational citizenship behavior, physical and psychological health, and turnover. a meta - analyses found job satisfaction to be related to life satisfaction, happiness, positive affect, and the
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counterproductive work behavior, customer service, cyberloafing, job performance, organizational citizenship behavior, physical and psychological health, and turnover. a meta - analyses found job satisfaction to be related to life satisfaction, happiness, positive affect, and the absence of negative affect. = = = productive behavior = = = productive behavior is defined as employee behavior that contributes positively to the goals and objectives of an organization. when an employee begins a new job, there is a transition period during which they may not contribute significantly. to assist with this transition an employee typically requires job - related training. in financial terms, productive behavior represents the point at which an organization begins to achieve some return on the investment it has made in a new employee. i - o psychologists are ordinarily more focused on productive behavior than job or task performance, including in - role and extra - role performance. in - role performance tells managers how well an employee performs the required aspects of the job ; extra - role performance includes behaviors that are not necessarily required by job but nonetheless contribute to organizational effectiveness. by taking both in - role and extra - role performance into account, an i - o psychologist is able to assess employees'effectiveness ( how well they do what they were hired to do ), efficiency ( outputs to relative inputs ), and productivity ( how much they help the organization reach its goals ). three forms of productive behavior that i - o psychologists often evaluate include job performance, organizational citizenship behavior ( see below ), and innovation. = = = = job performance = = = = job performance represents behaviors employees engage in while at work which contribute to organizational goals. these behaviors are formally evaluated by an organization as part of an employee's responsibilities. in order to understand and ultimately predict job performance, it is important to be precise when defining the term. job performance is about behaviors that are within the control of the employee and not about results ( effectiveness ), the costs involved in achieving results ( productivity ), the results that can be achieved in a period of time ( efficiency ), or the value an organization places on a given level of performance, effectiveness, productivity or efficiency ( utility ). to model job performance, researchers have attempted to define a set of dimensions that are common to all jobs. using a common set of dimensions provides a consistent basis for assessing performance and enables the comparison of performance across jobs. performance is commonly broken into two major categories : in - role ( technical aspects of a job ) and extra - role ( non - technical abilities such as communication skills and being a good
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consistent basis for assessing performance and enables the comparison of performance across jobs. performance is commonly broken into two major categories : in - role ( technical aspects of a job ) and extra - role ( non - technical abilities such as communication skills and being a good team member ). while this distinction in behavior has been challenged it is commonly made by both employees and management. a model of performance by campbell breaks performance into in - role and extra - role categories. campbell labeled job - specific task proficiency and non - job - specific task proficiency as in - role dimensions, while written and oral communication, demonstrating effort, maintaining personal discipline, facilitating peer and team performance, supervision and leadership and management and administration are labeled as extra - role dimensions. murphy's model of job performance also broke job performance into in - role and extra - role categories. however, task - orientated behaviors composed the in - role category and the extra - role category included interpersonally - oriented behaviors, down - time behaviors and destructive and hazardous behaviors. however, it has been challenged as to whether the measurement of job performance is usually done through pencil / paper tests, job skills tests, on - site hands - on tests, off - site hands - on tests, high - fidelity simulations, symbolic simulations, task ratings and global ratings. these various tools are often used to evaluate performance on specific tasks and overall job performance. van dyne and lepine developed a measurement model in which overall job performance was evaluated using campbell's in - role and extra - role categories. here, in - role performance was reflected through how well " employees met their performance expectations and performed well at the tasks that made up the employees'job. " dimensions regarding how well the employee assists others with their work for the benefit of the group, if the employee voices new ideas for projects or changes to procedure and whether the employee attends functions that help the group composed the extra - role category. to assess job performance, reliable and valid measures must be established. while there are many sources of error with performance ratings, error can be reduced through rater training and through the use of behaviorally - anchored rating scales. such scales can be used to clearly define the behaviors that constitute poor, average, and superior performance. additional factors that complicate the measurement of job performance include the instability of job performance over time due to forces such as changing performance criteria, the structure of the job itself and the restriction of variation in individual performance by organizational forces. these factors include errors in job measurement techniques, acceptance and the justification of poor performance
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the instability of job performance over time due to forces such as changing performance criteria, the structure of the job itself and the restriction of variation in individual performance by organizational forces. these factors include errors in job measurement techniques, acceptance and the justification of poor performance, and lack of importance of individual performance. the determinants of job performance consist of factors having to do with the individual worker as well as environmental factors in the workplace. according to campbell's model of the determinants of job performance, job performance is a result of the interaction between declarative knowledge ( knowledge of facts or things ), procedural knowledge ( knowledge of what needs to be done and how to do it ), and motivation ( reflective of an employee's choices regarding whether to expend effort, the level of effort to expend, and whether to persist with the level of effort chosen ). the interplay between these factors show that an employee may, for example, have a low level of declarative knowledge, but may still have a high level of performance if the employee has high levels of procedural knowledge and motivation. regardless of the job, three determinants stand out as predictors of performance : ( 1 ) general mental ability ( especially for jobs higher in complexity ) ; ( 2 ) job experience ( although there is a law of diminishing returns ) ; and ( 3 ) the personality trait of conscientiousness ( people who are dependable and achievement - oriented, who plan well ). these determinants appear to influence performance largely through the acquisition and usage of job knowledge and the motivation to do well. further, an expanding area of research in job performance determinants includes emotional intelligence. = = = = organizational citizenship behavior = = = = organizational citizenship behaviors ( ocbs ) are another form of workplace behavior that i - o psychologists are involved with. ocbs tend to be beneficial to both the organization and other workers. dennis organ ( 1988 ) defines ocbs as " individual behavior that is discretionary, not directly or explicitly recognized by the formal reward system, and that in the aggregate promotes the effective functioning of the organization. " behaviors that qualify as ocbs can fall into one of the following five categories : altruism, courtesy, sportsmanship, conscientiousness, and civic virtue. ocbs have also been categorized in other ways too, for example, by their intended targets individuals, supervisors, and the organization as a whole. other alternative ways of categorizing ocbs
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##scientiousness, and civic virtue. ocbs have also been categorized in other ways too, for example, by their intended targets individuals, supervisors, and the organization as a whole. other alternative ways of categorizing ocbs include " compulsory ocbs ", which are engaged in owing to coercive persuasion or peer pressure rather than out of good will. the extent to which ocbs are voluntary has been the subject of some debate. other research suggests that some employees perform ocbs to influence how they are viewed within the organization. while these behaviors are not formally part of the job description, performing them can influence performance appraisals. researchers have advanced the view that employees engage in ocbs as a form of " impression management, " a term coined by erving goffman. goffman defined impression management as " the way in which the individual... presents himself and his activity to others, the ways in which he guides and controls the impression they form of him, and the kinds of things he may and may not do while sustaining his performance before them. some researchers have hypothesized that ocbs are not performed out of good will, positive affect, etc., but instead as a way of being noticed by others, including supervisors. = = = = innovation = = = = four qualities are generally linked to creative and innovative behaviour by individuals : task - relevant skills ( general mental ability and job specific knowledge ). task specific and subject specific knowledge is most often gained through higher education ; however, it may also be gained by mentoring and experience in a given field. creativity - relevant skills ( ability to concentrate on a problem for long periods of time, to abandon unproductive searches, and to temporarily put aside stubborn problems ). the ability to put aside stubborn problems is referred to by jex and britt as productive forgetting. creativity - relevant skills also require the individual contributor to evaluate a problem from multiple vantage points. one must be able to take on the perspective of various users. for example, an operation manager analyzing a reporting issue and developing an innovative solution would consider the perspective of a sales person, assistant, finance, compensation, and compliance officer. task motivation ( internal desire to perform task and level of enjoyment ). at the organizational level, a study by damanpour identified four specific characteristics that may predict innovation : a population with high levels of technical knowledge the organization's level of specialization the level an organization communicates externally functional differentiation. = = =
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). at the organizational level, a study by damanpour identified four specific characteristics that may predict innovation : a population with high levels of technical knowledge the organization's level of specialization the level an organization communicates externally functional differentiation. = = = counterproductive work behavior = = = counterproductive work behavior ( cwb ) can be defined as employee behavior that goes against the goals of an organization. these behaviors can be intentional or unintentional and result from a wide range of underlying causes and motivations. some cwbs have instrumental motivations ( e. g., theft ). it has been proposed that a person - by - environment interaction can be utilized to explain a variety of counterproductive behaviors. for instance, an employee who sabotages another employee's work may do so because of lax supervision ( environment ) and underlying psychopathology ( person ) that work in concert to result in the counterproductive behavior. there is evidence that an emotional response ( e. g., anger ) to job stress ( e. g., unfair treatment ) can motivate cwbs. the forms of counterproductive behavior with the most empirical examination are ineffective job performance, absenteeism, job turnover, and accidents. less common but potentially more detrimental forms of counterproductive behavior have also been investigated including violence and sexual harassment. = = = leadership = = = leadership can be defined as a process of influencing others to agree on a shared purpose, and to work towards shared objectives. a distinction should be made between leadership and management. managers process administrative tasks and organize work environments. although leaders may be required to undertake managerial duties as well, leaders typically focus on inspiring followers and creating a shared organizational culture and values. managers deal with complexity, while leaders deal with initiating and adapting to change. managers undertake the tasks of planning, budgeting, organizing, staffing, controlling, and problem solving. in contrast, leaders undertake the tasks of setting a direction or vision, aligning people to shared goals, communicating, and motivating. approaches to studying leadership can be broadly classified into three categories : leader - focused approaches, contingency - focused approaches, and follower - focused approaches. = = = = leader - focused approaches = = = = leader - focused approaches look to organizational leaders to determine the characteristics of effective leadership. according to the trait approach, more effective leaders possess certain traits that less effective leaders lack. more recently, this approach is being used to predict leader emergence. the following traits have been identified as those that
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organizational leaders to determine the characteristics of effective leadership. according to the trait approach, more effective leaders possess certain traits that less effective leaders lack. more recently, this approach is being used to predict leader emergence. the following traits have been identified as those that predict leader emergence when there is no formal leader : high intelligence, high needs for dominance, high self - motivation, and socially perceptive. another leader - focused approached is the behavioral approach, which focuses on the behaviors that distinguish effective from ineffective leaders. there are two categories of leadership behaviors : consideration and initiating structure. behaviors associated with the category of consideration include showing subordinates they are valued and that the leader cares about them. an example of a consideration behavior is showing compassion when problems arise in or out of the office. behaviors associated with the category of initiating structure include facilitating the task performance of groups. one example of an initiating structure behavior is meeting one - on - one with subordinates to explain expectations and goals. the final leader - focused approach is power and influence. to be most effective, a leader should be able to influence others to behave in ways that are in line with the organization's mission and goals. how influential a leader can be depends on their social power β their potential to influence their subordinates. there are six bases of power : french and raven's classic five bases of coercive, reward, legitimate, expert, and referent power, plus informational power. a leader can use several different tactics to influence others within an organization. these include : rational persuasion, inspirational appeal, consultation, ingratiation, exchange, personal appeal, coalition, legitimating, and pressure. = = = = contingency - focused approaches = = = = of the 3 approaches to leadership, contingency - focused approaches have been the most prevalent over the past 30 years. contingency - focused theories base a leader's effectiveness on their ability to assess a situation and adapt their behavior accordingly. these theories assume that an effective leader can accurately " read " a situation and skillfully employ a leadership style that meets the needs of the individuals involved and the task at hand. a brief introduction to the most prominent contingency - focused theories will follow. the fiedler contingency model holds that a leader's effectiveness depends on the interaction between their characteristics and the characteristics of the situation. path β goal theory asserts that the role of the leader is to help their subordinates achieve their goals. to effectively do this, leaders must skillfully select from four different leadership
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effectiveness depends on the interaction between their characteristics and the characteristics of the situation. path β goal theory asserts that the role of the leader is to help their subordinates achieve their goals. to effectively do this, leaders must skillfully select from four different leadership styles to meet the situational factors. the situational factors are a product of the characteristics of subordinates and the characteristics of the environment. the leader β member exchange theory ( lmx ) focuses on how leader β subordinate relationships develop. generally speaking, when a subordinate performs well or when there are positive exchanges between a leader and a subordinate, their relationship is strengthened, performance and job satisfaction are enhanced, and the subordinate will feel more commitment to the leader and the organization as a whole. vroom - yetton - jago model focuses on decision - making with respect to a feasibility set. = = = = organizational development = = = = i - o psychologists may also become involved with organizational change, a process which some call organizational development ( od ). tools used to advance organization development include the survey - feedback technique. the technique involves the periodic assessment ( via surveys ) of employee attitudes and feelings. the results are conveyed to organizational stakeholders, who may want to take the organization in a particular direction. another tool is the team - building technique. because many if not most tasks within an organization are completed by small groups and / or teams, team building can become important for organizational success. in order to enhance a team's morale and problem - solving skills, i - o psychologists help the groups to improve their self - confidence, group cohesiveness, and working effectiveness. = = = work β nonwork interface = = = an important topic in i - o is the connection between people β s working and nonworking lives. two concepts are particularly relevant. work β family conflict is the incompatibility between the job and family life. conflict can occur when stressful experiences in one domain spillover into the other, such as someone coming home in a bad mood after having a difficult day at work. it can also occur when there are time conflicts, such as having a work meeting at the same time as a child β s doctor β s appointment. work β family enrichment ( also called work β family facilitation ) occurs when one domain provides benefits to the other. for example, a spouse might assist with a work task or a supervisor might offer assistance with a family problem. = = = relation to organizational behavior and human resource management = = = i - o psychology and organizational behavior researchers
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provides benefits to the other. for example, a spouse might assist with a work task or a supervisor might offer assistance with a family problem. = = = relation to organizational behavior and human resource management = = = i - o psychology and organizational behavior researchers have sometimes investigated similar topics. the overlap has led to some confusion regarding how the two disciplines differ. sometimes there has been confusion within organizations regarding the practical duties of i - o psychologists and human resource management specialists. = = as an occupation = = = = = training = = = the minimum requirement for working as an i - o psychologist is a master's degree. normally, this degree requires about two to three years of postgraduate work to complete. of all the degrees granted in i - o psychology each year, approximately two - thirds are at the master's level. : 18 a comprehensive list of us and canadian master's and doctoral programs can be found at the web site of the society for industrial and organizational psychology ( siop ). admission into i - o psychology phd programs is highly competitive ; many programs accept only a small number of applicants each year. there are graduate degree programs in i - o psychology outside of the us and canada. the siop web site lists some of them. in australia, organisational psychologists must be accredited by the australian psychological society ( aps ). to become an organisational psychologist, one must meet the criteria for a general psychologist's licence : three years studying bachelor's degree in psychology, 4th - year honours degree or postgraduate diploma in psychology, and two - year full - time supervised practice plus 80 hours of professional development. there are other avenues available, such as a two - year supervised training program after honours ( i. e. 4 + 2 pathway ), or one year of postgraduate coursework and practical placements followed by a one - year supervised training program ( i. e. 5 + 1 pathway ). after this, psychologists can elect to specialise as organisational psychologists in australia. = = = competencies = = = there are many different sets of competencies for different specializations within i - o psychology and i - o psychologists are versatile behavioral scientists. for example, an i - o psychologist specializing in selection and recruiting should have expertise in finding the best talent for the organization and getting everyone on board while they might not need to know much about executive coaching. some i - o psychologists specialize in specific areas of consulting whereas others tend to generalize their areas of expertise. there are basic skills and knowledge an individual needs in order
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getting everyone on board while they might not need to know much about executive coaching. some i - o psychologists specialize in specific areas of consulting whereas others tend to generalize their areas of expertise. there are basic skills and knowledge an individual needs in order to be an effective i - o psychologist, which include being an independent learner, interpersonal skills ( e. g., listening skills ), and general consultation skills ( e. g., skills and knowledge in the problem area ). = = = job outlook = = = u. s. news & world report lists i - o psychology as the third best science job, with a strong job market in the u. s. in the 2020 siop salary survey, the median annual salary for a phd in i - o psychology was $ 125, 000 ; for a master's level i - o psychologist was $ 88, 900. the highest paid phd i - o psychologists were self - employed consultants who had a median annual income of $ 167, 000. the highest paid in private industry worked in it ( $ 153, 000 ), retail ( $ 151, 000 ) and healthcare ( $ 147, 000 ). the lowest earners were found in state and local government positions, averaging approximately $ 100, 000, and in academic positions in colleges and universities that do not award doctoral degrees, with median salaries between $ 80, 000 and $ 94, 000. = = ethical principles = = an i - o psychologist, whether an academic, consultant or an employee of an organization, is expected to maintain high ethical standards. siop encourages its members to follow the apa ethics code. with more organizations becoming global, it is important that when an i - o psychologist works outside their home country, the psychologist is aware of rules, regulations, and cultures of the organizations and countries in which the psychologist works, while also adhering to the ethical standards set at home. = = see also = = = = references = = footnotes = = further reading = = = = external links = = canadian society for industrial and organizational psychology british psychological society's division of occupational psychology's ( dop ) website society for industrial and organisational psychology of south africa european academy of occupational health psychology european association of work and organizational psychology society for industrial and organizational psychology alliance for organizational psychology
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a quotation or quote is the repetition of a sentence, phrase, or passage from speech or text that someone has said or written. in oral speech, it is the representation of an utterance ( i. e. of something that a speaker actually said ) that is introduced by a quotative marker, such as a verb of saying. for example : john said : " i saw mary today ". quotations in oral speech are also signaled by special prosody in addition to quotative markers. in written text, quotations are signaled by quotation marks. quotations are also used to present well - known statement parts that are explicitly attributed by citation to their original source ; such statements are marked with ( punctuated with ) quotation marks. as a form of transcription, direct or quoted speech is spoken or written text that reports speech or thought in its original form phrased by the original speaker. in narrative, it is usually enclosed in quotation marks, but it can be enclosed in guillemets ( Β« Β» ) in some languages. the cited speaker either is mentioned in the tag ( or attribution ) or is implied. direct speech is often used as a literary device to represent someone's point of view. quotations are also widely used in spoken language when an interlocutor wishes to present a proposition that they have come to know via hearsay. = = comparison between direct, indirect, and free indirect speech = = quoted or direct speech : direct speech and indirect speech can also refer to the difference between speech acts where the illocutionary force is conveyed directly and indirectly, respectively. thus, " what time is it? " is a direct speech act that might also be expressed by the indirect speech act " do you know what time it is? " he laid down his bundle and thought of his misfortune. " and just what pleasure have i found since i came into this world? " he asked. reported or normal indirect speech : he laid down his bundle and thought of his misfortune. he asked himself what pleasure he had found since he came into the world. free indirect speech : he laid down his bundle and thought of his misfortune. and just what pleasure had he found since he came into this world? a crucial semantic distinction between direct and indirect speech is that direct speech purports to report the exact words that were said or written, whereas indirect speech is a representation of speech in one's own words. the distinction between indirect speech and free indirect speech is
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distinction between direct and indirect speech is that direct speech purports to report the exact words that were said or written, whereas indirect speech is a representation of speech in one's own words. the distinction between indirect speech and free indirect speech is mostly one of style, hence free indirect speech is sometimes described as a free indirect style. = = as a literary device = = a quotation can also refer to the repeated use of units of any other form of expression, especially parts of artistic works : elements of a painting, scenes from a movie or sections from a musical composition. = = = reasons for using = = = quotations are used for a variety of reasons : to illuminate the meaning or to support the arguments of the work in which it is being quoted, to provide direct information about the work being quoted ( whether in order to discuss it, positively or negatively ), to pay homage to the original work or author, to make the user of the quotation seem well - read, and / or to comply with copyright law. quotations are also commonly printed as a means of inspiration and to invoke philosophical thoughts from the reader. pragmatically speaking, quotations can also be used as language games ( in the wittgensteinian sense of the term ) to manipulate social order and the structure of society. = = = common sources = = = famous quotations are frequently collected in books that are sometimes called quotation dictionaries or treasuries. of these, bartlett's familiar quotations, the oxford dictionary of quotations, the columbia dictionary of quotations, the yale book of quotations and the macmillan book of proverbs, maxims, and famous phrases are considered among the most reliable and comprehensive sources. diaries and calendars often include quotations for entertainment or inspirational purposes, and small, dedicated sections in newspapers and weekly magazines β with recent quotations by leading personalities on current topics β have also become commonplace. = = = misquotations = = = many quotations are routinely incorrect or attributed to the wrong authors, and quotations from obscure or unknown writers are often attributed to far more famous writers. examples of this are winston churchill, to whom many political quotations of uncertain origin are attributed, and oscar wilde, to whom anonymous humorous quotations are sometimes attributed. some quotations commonly believed to be quotations from literature, film, etc. do not actually appear in the source material, but are paraphrases of phrases that do. the star trek catchph
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whom anonymous humorous quotations are sometimes attributed. some quotations commonly believed to be quotations from literature, film, etc. do not actually appear in the source material, but are paraphrases of phrases that do. the star trek catchphrase " beam me up, scotty " did not appear in that form in the original series. other misquotations include " just the facts, ma'am " ( attributed to jack webb's character of joe friday on dragnet ), " heavy lies the crown " from shakespeare's play henry iv, part 2, " elementary, my dear watson " ( attributed to sherlock holmes ; it was, however, said in the films the adventures of sherlock holmes and the return of sherlock holmes ), " luke, i am your father " ( attributed to darth vader in star wars ), " play it again, sam " ( attributed to ilsa in casablanca ), " do you feel lucky, punk? " ( attributed to harry callahan in dirty harry ) and " we don't need no stinkin'badges! " ( attributed to gold hat in the treasure of the sierra madre ). = = = quotative inversion = = = quotative inversion occurs in sentences where the direct quotation can occur before a verb of saying or after a verb of saying. it can trigger inversion of the verb and the verb's subject. subject - verb inversion occurs most often in written works, being rare in speech. quotations may appear before the inverted verb, but can also appear after the subject, such as : " i am going to follow you all the rest of my life, " declared the man and said the woman : " i see you with both my eyes. " also referred to as inverted quotations, this technique of reversing the sequence of an existing phrase or formulation is commonly found in biblical texts, particularly the hebrew bible and the new testament. it serves to evoke various emotional and rhetorical effects, mainly to draw extra attention from the reader or listener. by reversing a previously established sequence, authors can introduce surprise, emphasize key points, or create contrasts that highlight the text's significance and its connections to other biblical passages. = = = = syntax = = = = in syntactic terms, these direct quotations can be presented in two forms. the first is as the complement of a quotative verb ( e. g. marie said : " my brother has arrived " ), and the second being as a head clause with
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##ctic terms, these direct quotations can be presented in two forms. the first is as the complement of a quotative verb ( e. g. marie said : " my brother has arrived " ), and the second being as a head clause with a quotative adjunct ( e. g. " my brother has arrived ", marie announces ). the verb phrase can be further expanded to include a complement, such as : " they'll never make it! " cried john to mary. subjects must precede the complement, otherwise the structure formed will be ungrammatical ( e. g. * " they'll never make it! " cried to mary john ). quotative inversion is only allowed when the verb is in the simple present or the simple past. the most common pairing is the verb said with a nominal subject, such as : " that's the whole trouble, " said gwen. additionally, noun phrases are not permitted in addition to the subject when inversion takes place. they are allowed only when there is no subject - verb inversion, or when part of a preposition phrase. a. " why? " gabrielle asked the attendant. - no subject - verb inversion b. " why? " asked gabrielle of the attendant. - np part of a preposition phrase c. * " why? " asked gabrielle the attendant. - subject - verb inversion unlikely with an np in addition to the subject in english, both verb - subject and subject - verb word orders are permitted : a. " don't turn back! " warned marcel. - verb - subject order b. " who's on first? " swami demanded. - subject - verb order this however, is not the case in all languages. for example, in peninsular spanish, this inversion is not allowed. quotatives must follow verb - subject order : a. Β« no, no es un enanito Β», rectifica el viejo. - verb - subject order " no, he is not a gnome ", corrects the old man. b. * Β« no, no es un enanito Β», el viejo rectifica. - subject - verb order unlikely for introducing quotations " no, he is not a gnome ", the old man corrects. = = = brackets in quotes in english language = = = brackets are used to indicate an addition or a modification from the original quote. various uses of brackets in quotes are : clarification ( " she [ michelle ] is an expert in botany.
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= = = brackets in quotes in english language = = = brackets are used to indicate an addition or a modification from the original quote. various uses of brackets in quotes are : clarification ( " she [ michelle ] is an expert in botany. " ) change in capitalization ( " [ a ] ccording to this article, this is untrue. " ) translation ( " hola, soy brandon [ hello, i am brandon ]. " ) when " [ sic ] " is added, it means that errors are present in the original text. for example, " domestic cats are valued by hoomans [ sic ] for companionship. " = = in spoken discourse = = traditionally, quotations β more specifically known as direct quotations β have been distinguished from indirect quotations. direct quotations differ from indirect quotations in that they are reported from the perspective of the experiencer, while indirect quotations are reported from the perspective of the reporting speaker ( e. g. " he said :'i am leaving now'" versus " he said ( that ) he was leaving immediately " ) ; are free in their syntactic form, while indirect quotations are subject to language - specific structural requirements ( e. g. indirect quotations in many indo - european languages are required to have the syntactic form of a well - formed declarative subordinate clause ) ; incorporate extralinguistic material and pragmatic markers, while indirect quotations do not. crucially, direct quotations have a performative aspect ( i. e. occur simultaneously with re - enactments of previous behaviours ), which indirect quotations lack. both direct and indirect quotations in spoken discourse are not intended to be verbatim reproductions of an utterance that has been produced. instead, direct quotations convey the approximative meaning of such an utterance along with the way in which that utterance was produced. from a sociolinguistic perspective, a direct quotation in spoken discourse can therefore also be defined as " a performance whereby speakers re - enact previous behaviour ( speech / thought / sound / voice effect and gesture ) while assuming the dramatic role of the original source of this reported behaviour ". indirect quotations are simply paraphrases of something that a reporting speaker heard. = = = reasons for using = = = quotations are employed in spoken discourse for many reasons. they are often used by speakers to depict stories and events that have occurred in the past to other interlocutors.
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that a reporting speaker heard. = = = reasons for using = = = quotations are employed in spoken discourse for many reasons. they are often used by speakers to depict stories and events that have occurred in the past to other interlocutors. the speaker does not necessarily have to have been an original participant in the story or event. therefore, they can quote something that they did not hear firsthand. quotations are also used to express thoughts that have never been uttered aloud prior to being quoted. for example, while telling a story, a speaker quotes inner thoughts that they had during a specific situation. finally, speakers use quotations to propose future dialogue for participants in a situation that may take place in the future. for example, two friends talk about their 10 - year high school reunion that will take place in the future and propose what they would say. while future dialogue can be proposed for a situation that will likely happen, it can also be based on a situation that will not actually take place. in the latter usage, the proposed dialogue only exists in the conversational context. the quoted material is usually not a verbatim replication of an utterance that someone originally said. instead, quotations in spoken discourse reproduce what a speaker wishes to communicate to their recipients ; quotations demonstrate something that someone said, the manner in which that person said it, and the current speaker β s feelings about what was said. in this way, quotations are an especially effective storytelling device ; the speaker is able to give a voice to the protagonists in their stories themselves, which allows the speaker β s audience to experience the situation in the way that the speaker themselves experienced it. = = = form = = = in most languages, quotations in spoken discourse are introduced by a verb of saying and a pronoun. for example, a quotation in english can be introduced by " she said ". in some languages, there is a discourse marker in addition to the verb of saying that functions as verbal quotation marks. for example, japanese uses the quotative particle ( a type of quotative marker ) to along with the conjugated verb of saying itta : verbs of saying ( known as quotative verbs when used to introduce quotations ) and quotative particles are used as quotative markers, which signal quotations in utterances. quotative evidentials are also used in some languages to indicate quoted speech ( e. g. cusco quechua spoken in peru, nanti spoken in lowland southeastern peru, laal spoken in chad ).
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which signal quotations in utterances. quotative evidentials are also used in some languages to indicate quoted speech ( e. g. cusco quechua spoken in peru, nanti spoken in lowland southeastern peru, laal spoken in chad ). = = = = quotative markers = = = = quotative markers are used to mark a section of an utterance as quoted speech ( i. e. a quotation ). in oral speech, quotative markers act as quotation marks and often include a verb of saying ( e. g. say ). a quotative marker usually appears either before or after the reported speech or thought, depending on the syntax of the language. for example, compare the following languages : = = = = = english = = = = = in english, the quotative verb say occurs before the quotation : a. she said " will you answer the phone, will you answer the phone " in american english, verbs such as be like, go, and be all are non - standard quotatives that are commonly used in colloquial speech. they are observed in the speech of young people not only in american english, but in other varieties of english as well ( e. g. be like in new zealand english, be like and go in glasgow english ). though not semantically considered verbs of saying, they are used to convey the same meaning as such verbs. like say, be like, go, and be all occur before the quotation : b. i'm like " i'm so sorry you had to wait " c. she went " who are you going with? " d. he's all " okay, come with me come with me " in conversational speech, the use of say and be like occurs at about the same frequency, though say tends to be used in more formal contexts ( e. g. office hours between professors and students ) and be like tends to occur in more informal contexts ( e. g. a conversation between two young people ). in african american vernacular english, talkin'' bout occurs as a verb of quotation, introducing both direct and indirect quotes, as in : e. they come talkin'' bout they is scared of me! = = = = = japanese = = = = = in japanese, the quotative particle to along with the verb of saying iu ( say ) occur after the quotation ; the conjugated form of iu ( say ) is itta : the quotative particle to
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= = = = = in japanese, the quotative particle to along with the verb of saying iu ( say ) occur after the quotation ; the conjugated form of iu ( say ) is itta : the quotative particle to can also occur with verbs of thinking, such as omou ( think ). like to and iu ( say ), to and omou occur after the quotation. = = = = = laal = = = = = in laal, the quotative evidential mɨ is used for non - self quotation ( i. e. quotation in which the speaker quotes someone else, not themself ) ; it is used with a quotative verb. the use of mɨ results in an indirect quotation translation. the quotative verb bɨla occurs before the quotation, while the quotative evidential mɨ occurs within the quoted speech ja mɨ nyag taa wo : as the above sentence involves a non - self quotation, a ( he ) and ja ( i ) have different indices to show that they refer to different referents ; only this interpretation is well - formed. the interpretation in which they share identical indices is ill - formed ( i. e. ungrammatical ), as indicated by the asterisk. in addition to quotative markers, speakers also use prosodic shifts, pauses, pronominal choices, and tense to detect the occurrence and boundaries of quotations in spoken utterances. = = = syntax = = = different versions of quotative verbs, particles, and evidentials can be used to express the same idea with varying nuances, often to frame how the primary speaker, or the person who is quoting, feels about a quotation. the syntax of quotations varies cross - linguistically. a primary speaker may use the tense and linguistic idiosyncrasies of the speech at the time it was uttered in a quotation, independent from the tense in the main clause in some languages, or use the same tense in both the main clause and quotation in other languages. they will also use coreferenced pronouns to the direct quotation's first - person subject in the main clause : shex said, " ix... " ; theyy said " wey... " in many languages, the primary speaker may also attempt to quote an utterance in the same language the original speaker used, even if an interlocutor does not understand it ; however,
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" ; theyy said " wey... " in many languages, the primary speaker may also attempt to quote an utterance in the same language the original speaker used, even if an interlocutor does not understand it ; however, it is mainly context - dependent such as when telling stories. = = = = quotative verbs = = = = quotative verbs are lexical verbs that indicate the speech, thoughts, or perceptions of the original speaker. quotations can be introduced as the complement to a quotative verb or as the head phrase to an adjunct phrase containing a quotative verb in some languages like english and french. english also displays verb - second ( v2 ) order vestige only in quotation contexts ( quotative inversion ), requiring the finite verb to appear in the second position of a clause. for example : " no no no " says harry. direct and indirect quotations are sometimes not distinguishable. traditionally, english uses an overt complementizer that after a quotative verb to indicate indirect quotation, but it is also seen to prompt direct quotation in some english varieties like indian english, hong kong english, and kenyan english. the newer quotative verb be like in english is used to only introduce direct quotations. be like includes the use of the demonstrative that, which is null in most english varieties, but can be optionally overt in some varieties like glasgow english. dutch's quotative verb hebben zoiets van has a similar structure to standard american english in that it has a null demonstrative that precedes the quotation. it differs from the english structures in that it uses an overt quantifier zoiets to be well - formed. = = = = quotative particles = = = = quotative or hearsay particles are grammatical markers equivalent to full lexical verbs with meanings of " say, mention, tell, etc. " in many languages, they are grammaticalized to different extremes from their previously lexical form. common patterns of grammaticalization trajectories include verb to complementizer in many african and asian languages and verb to tense - aspect - mood markers primarily in african languages, but also in australian languages and multiple other language families. japanese, for example, uses a sentence - final quotative particle tte verbally to mean " i heard ( quote ) " with some uncertainty. in sentence - medial position, tte is sometimes regarded along with to to be either a quotative particle or complementizer meaning " i heard
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- final quotative particle tte verbally to mean " i heard ( quote ) " with some uncertainty. in sentence - medial position, tte is sometimes regarded along with to to be either a quotative particle or complementizer meaning " i heard ( quote ) " with less uncertainty and often more knowledge of the origin of the quote. verbs of saying are highly restricted in australian languages and almost always immediately proceed the complement verb. = = = = quotative evidentials = = = = quotative or hearsay evidentials provide knowledge of who or where information originated from in speech based on logical assumption. languages indicate this in various ways : through grammatical marking, additional words and phrases, prosody, gestures, or systematic affixes of verbs. quotative readings of evidentials are typologically rare. for example, english can express evidentials with an optional adverb, " allegedly, annie pulled the trigger. " the interlocutor then knows the source of the quotation is from elsewhere, but this is not a quotative reading as there is no direct performative quoting or verbs of saying. languages including cusco quechua, kham, tagalog, and kaalallisut are documented as containing quotative evidentials. in languages with " true " quotative evidentials ( which usually introduce quoted statements ), it is also possible for them to occur with interrogatives and imperatives, yielding quoted interrogatives and quoted imperatives. similar to quotative particles, quotative evidentials are usually grammaticalized from full lexical verbs. nheengatu, a tupi - guarani lingua franca of north - west amazonia, has a reported evidential marker paa. an example scenario is as follows : x saw john go fishing. mary then and asks x where john went. x replies " u - su u - piniatika " ( he went fishing ). later, peter asks mary where john went. she replies to peter that she did not see john go herself, but rather heard it from a different source using the evidential marker " u - su u - piniatika paa. " tagalog's quotative evidentials are used with imperative quotations. cusco quechua's quotative evidential comes as a derivation of a clitic, = si, for interrogative quotations. = = = hand gesture = = = hand gesturing a quotation in a conversation can be done with air quotes. = =
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' s quotative evidential comes as a derivation of a clitic, = si, for interrogative quotations. = = = hand gesture = = = hand gesturing a quotation in a conversation can be done with air quotes. = = see also = = = = notes = = = = references = =
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the harvard plate stacks, previously known as the harvard college observatory's glass plate collection or the astronomical photographic glass plate collection is the largest collection of photographic glass plate negatives of the night sky in the world. the collection was created across a century by the harvard college observatory. many of the people who worked in and studied the collection were a group of famous female astronomers called the harvard computers. it is a scientific and historical collection at the the center for astrophysics | harvard & smithsonian ( cfa ) in cambridge, massachusetts. = = scope and size = = the harvard plate stacks collection consists of over 550, 000 glass plate negatives of the night sky. the glass alone is estimated to weight over 165 tons and stored across three floors of a purpose built building on observatory hill in cambridge, ma. the majority of the collection consists of the astronomical glass plates, with most of these being gelatin dry - plate negatives. astronomically, the collection consists of both direct image and spectral plates with a third of the collection made up of the later. the collection is also mostly known for it widefield imagery and consists of 20 % of the known plates ever taken. the glass plates negatives date from the 1870s to the late 1990s. any given region of the night sky appears on between 500 - 1, 000 plates across a century of time. both in number of observations and time, the collection will not be surpassed by digitally collected data until projects like the lsst at the vera rubin observatory complete hundreds of observations and until a century of digital ccd imaging in the 2080s. photographically, the collection spans the history of the analogue photographic medium. while the majority of the collection is photographic negatives, there is a large collection of photographic prints across the same century of time. archivally, the collection consists of materials like the 2, 500 individual notebooks of researchers who were hired to study the plates. these notebooks include those made by some of the most famous astronomers at the harvard college observatory including, williamina fleming, antonia maury, henrietta swan leavitt, annie jump cannon, and cecilia payne - gaposchkin. the plate stacks also holds 1, 200 logbooks that recorded the metadata of each plate when it was created including the observator who made the image. = = earliest parts of the collection = = the collection starts at the dawn of photography with some of the earliest images created of objects in space. these include an early collection of daguerreotypes, including a collection made by photographer john adams whipple
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= earliest parts of the collection = = the collection starts at the dawn of photography with some of the earliest images created of objects in space. these include an early collection of daguerreotypes, including a collection made by photographer john adams whipple collaborating with father - son astronomers william cranch bond and george bond. the oldest dated image in the collection is a multiple exposure daguerreotype of the moon made by samuel dwight humphrey on 1 september 1849. this is the second oldest extant image of the moon know to survive, only surpassed by the john william draper's photograph of the moon now at the new york university libraries special collections. photographic firsts contained in the collection include the first photograph of an eclipse ( partial ) created by whipple on 28 july 1851 and the first photograph showing the " diamond ring " effect of a total solar eclipse by whipple in shelbyville, kentucky on 7 august 1869. it also includes the first photograph made of a comet made by william usherwood of the comet donati on 27 september 1858, and subsequent exposures made by george bond on 28 september 1858. while scientifically, photographically, and artistically significant, these earliest photographs were not created consistantly. instead these earliest examples of photography that include daguerreotypes, ambrotypes, wet plate collodion, and salt prints are photographic processes that require more light through longer exposure times than these media would allow to capture all but the brightest objects in the night sky. it was not until the invention of the dry plate negatives as a commercially available medium that the exposure length was no longer limited. = = anna palmer draper, edward pickering and the harvard computers = = following the american civil war, advances in photography and astronomy allowed for multiple pioneers to make advances in the burgeoning art and science of astrophotography. the british couple, margaret lindsay huggins and william huggins, would be credited with being the first to experiment using dry plate photography to capture astronomical objects in 1876. at the same time, the american couple, anna palmer draper and henry draper, had been experimenting with photography, spectroscopy, and astronomy in their personal observatory in hastings - on - hudson, new york. the drapers would be the first to successfully photograph a spectrum of a star, vega, in 1872 and be the first to capture the orion nebula on september 30, 1880, all with collodion photography. in massachusetts, the brothers william h. and edward c. pickering, would experiment with lenses and start systematically photographing the night sky
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in 1872 and be the first to capture the orion nebula on september 30, 1880, all with collodion photography. in massachusetts, the brothers william h. and edward c. pickering, would experiment with lenses and start systematically photographing the night sky by 1877. these three pairs of collaborators would exchange correspondences and share discoveries and advancements. on november 20, 1882, henry draper dies of " pleurisy " after returning home to new york from a hunting trip in colorado. in a letter from edward pickering to anna palmer draper dated 13 january 1883, he writes, " my dear mrs. draper, mr clark tells me that you are preparing to complete the work in which dr. draper was engaged, and my interest in this matter must be my excuse for addressing you regarding it. i need not state my satisfaction that you are taking this step, since it must be obvious that in no other way could you erect so lasting a monument to his memory. " this would be the beginning of anna draper being the single largest benefactor to the harvard college observatory for the next three decades. her funds and future endowment would back the creation, preservation, and housing of nearly 6000, 000 glass plates and the core of the harvard plate stacks collection, which would amount to a century of photographing the night sky. her gift would not only include funds but also her and her husband's personal telescope. she would establish the henry draper memorial, which would include both the creation of a physical photographic plate collection, as well as the study and publication of what is known as the henry draper catalogue. over 44 women would partake in the study, writing, and creation of the catalogue from 1886 until the final publication of henry draper extension charts in 1941. this would be part of the group of women known as the harvard computers or, more recently, referred to as the women astronomical computers at harvard. nearly 200 women would work at the harvard plate stacks during the century of the use of glass plate negatives, 1875 - 1975. their individual and collective legacies shaped the way we understand the universe. the outsized impact that one woman would have on an institution and field is summarized nearly a century later by pioneering female astrophysicist, dr. dorrit hoffleit, β there is hardly any branch of astronomy that has not benefited from the results of the henry draper memorial. without mrs. draper β s vision and generosity, one wonders how preeminent harvard would have become. β anna draper would also provide funds for the observatory to build three different buildings
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astronomy that has not benefited from the results of the henry draper memorial. without mrs. draper β s vision and generosity, one wonders how preeminent harvard would have become. β anna draper would also provide funds for the observatory to build three different buildings to house the harvard plate stacks including its current home built in 1931. she would also separately establish the henry draper medal, be a founder of the mount wilson observatory, and even establishing the draper collection of cuneiform at the new york public library. this individual support would be compounded by other donations, including the estate of uriah a. boyden to establish a southern hemisphere observatory, first called boyden station, and later boyden observatory. originally stablished in arequipa, peru in 1889, the observatory would be moved to maselspoort near bloemfontein, south africa where it still exists and operates under the physics department of the university of the free state ( ufs ) since 1976. over 60 % of the plate stacks collection would be made at these two locations. uniquely among other astronomical glass plate collections, the harvard plate stacks has an equal length history and even use of the same instruments to create plates of the northern and southern celestial hemispheres. this would lead to the creation of the " harvard map of the sky " in 1917, the first photographic image of the entire visible universe. printed on glass plate negatives from original plates deemed to be the best of each quadrant of the night sky, 55 glass plate negative which would alter be expanded to 74 plates would be copied using an interpostive process to create multiple copies of glass plate negatives for sale and distribution to other observatories, university, and libraries. the first sets were offered around 1905 along with the " first supplement to catalogue of variable stars. " according to williamina fleming's own published account, by october 1890, harvard had photographed both the northern and southern hemispheres from cambridge, ma and an earlier predecessor of the boyden observatory established on mount harvard near chosica, persu. this means that both the harvard plate stacks contains the first photographic atlas of the visible universe, and even predates the much more know international collaboration and multidecade publication, carte du ciel. the scale and volume of creating photographic plates would go largely unchanged with only minor pauses or lower production during the two world wars. other major donations for women would help shape the collection and advance the fields of astronomy and astrophysics. catherine wolfe bruce would find the creation of a 24 - in
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plates would go largely unchanged with only minor pauses or lower production during the two world wars. other major donations for women would help shape the collection and advance the fields of astronomy and astrophysics. catherine wolfe bruce would find the creation of a 24 - in doublet telescope honoring her husband. this telescope would fist be installed in massachusetts to capture the northern most stars before it was moved to a purpose built building at boyden in arequipa as its centerpiece. the bruce telescope was the largest astrograph at the time and would be used to create 30, 000 glass plates. these plates known as the a series, are the largest measuring 14x17 inches and are some of the farthest seeing plates in the collection. the boyden observatory was moved south africa, enabled by a grant of $ 200, 000 from the rockefeller foundation. abby aldrich rockefeller funded the creation of a 60 - in telescope. = = the menzel gap = = in 1952, donald howard menzel was appointed the director of the harvard college observatory. according to dorriet hoffliet, one of the first things he undertook with his new appointment was the systematic shuttering of the photographic program at harvard. this included abandoning the boyden observatory, and the culling of thousands of plates from 1960 - 1965 through the creation of a plate stacks committee that excluded the voices of the curator of the collection, as well as those employed at the time as computers. this committee would meet and vote to destroy whole series of plates including experimental plates and early spectra plates. because of harvard's outsized role in the creation of astronomical glass plates even in this era, the resulting gap in astronomical data from the 1950s to the 1960s is referred to as the " menzel gap " by modern astrophysicists. = = = armagh - dunsink - harvard telescope = = = in 1947 through a chance meeting in the shannon airport with harvard college observatory director, harlow shapley, and irish president ( taoiseach ), eamon de valera led to the idea and further creation of the armagh - dunsink - harvard telescope. though installed and housed at harvard's boyden observatory in south africa, this was a joint endeavor with armagh observatory in northern ireland, the republic of ireland, and harvard college observatory. this was one of the earlier examples of space diplomacy that would be spearheaded at harvard by astronomer bart bok. the director of the armagh observatory at the time was eric lindsay who not only got his phd from harvard in 1934, but he would meet and
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this was one of the earlier examples of space diplomacy that would be spearheaded at harvard by astronomer bart bok. the director of the armagh observatory at the time was eric lindsay who not only got his phd from harvard in 1934, but he would meet and later mary women astronomical computer, sylvia mussells ( sister to fellow astronomer and harvard plate stacks employee muriel mussells seyfert ). de valera recently pushed to create the dublin institute for advanced studies and its subsequent purchase of the dunsink observatory after trinity college dublin had ceased its operations a few years earlier. this cooperative agreement would be one of the rare instances where these two governments would regularly work together. the telescope was a 36 β 32 baker - schmidt telescope that received first light in october 1950. this telescope would make circular photographic plates from 1950 to 1963. the telescope would create 7, 087 glass plate negatives focusing on nebulas and clusters. the majority of these plates are still house at the plate stacks but some plates where known to be a dunsink observatory in 1995 and a small deposit of plates from this telescope was sent to pari in 2007. = = = damons = = = starting in 1961, the harvard college observatory would undertake its last multidecade analogue photographic survey of the night sky. first starting at harvard's oak ridge observatory in harvard, ma, then moving to boyden in south africa and later mt. john in new zealand, and cerro tololo would be the site of three " patrol camera " which were 13. 9 in telescope that systematically photographed the night sky using three filters ( red, yellow, blue ) concurrently. this would result in the creation of 12, 374 glass plate negatives covering the entire sky from 1961 to 1990. though these 8 x 10 plates capture a wide field of view, the advances in dry plate photography allowed for the capturing of the faintest objects captured on plates in the collection. = = = subsequent additions = = = in addition to the plates and different campaigns made by the harvard college observatory, there are other smaller but important additions to the collection of materials made by other departments at the center for astrophysics or other observatories. the meteor department at the center for astrophysics was first a part of the harvard college observatory but when fred whipple was named director of the smithsonian astrophysical observatory, he moved the department over to the smithsonian so it could continue under his leadership. this group would create thousands of glass plate negatives as well as film exposures of the night sky, ranging
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whipple was named director of the smithsonian astrophysical observatory, he moved the department over to the smithsonian so it could continue under his leadership. this group would create thousands of glass plate negatives as well as film exposures of the night sky, ranging in scale and scope over time. before this department transitioned into its current iteration as the minor planet center, its analogue holdings were transferred over to the harvard plate stacks. this would be the most significant addition to the collection in its history, numbering near 100, 000 items. during the physical reorganization of the collection space, as well as the priorities put onto the collection during the dasch project, the lion's share of these materials were deposited at pari. until both institutions complete an inventory of the collections they hold, the number of surviving items is unknown. also in relation to the dasch project, the space telescope science institute transferred its holdings of various later analogue sky surveys that were digitized as part of the digitized sky survey. these include the national geographic society β palomar observatory sky survey, european southern observatory sro sky surveys, and the uk schmidt telescope southern survey. as of 2025, these plates are being scanned by the dasch scanner, though at a slower rate. = = dasch = = the digital access to a sky century @ harvard ( dasch ) was a project that started in 2001 with the intent of digitizing the glass plates in the plate collection as well as the metadata from the logbooks that supported these plates. the final data release in 2024 contained data for 429, 274 glass plates, making them accessible to the public for viewing. on december 29, 2024, dasch's successor, starglass, was launched. starglass is hosted on the cloud and is publicly available for anyone to view, allowing searches to be done for plates worked on by a specific astronomer, plates that show specific celestial objects, and much more. = = noteable people = = williamina fleming β first curator of the collection and head of the department from ca. 1879 to 1911. antonia maury β niece of anna draper and builds on fleming's stellar classification henrietta swan leavitt β discovers the period - luminosity relation of cephids on plates of the large and small magellanic clouds, now known at the leavitt law. annie jump cannon β editor of the draper catalogue and named second curator 1911 but does not receive the official appointment until 1938 and retires in 1940. cecilia payne - gaposchkin β first phd in astronomy awarded by
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known at the leavitt law. annie jump cannon β editor of the draper catalogue and named second curator 1911 but does not receive the official appointment until 1938 and retires in 1940. cecilia payne - gaposchkin β first phd in astronomy awarded by radcliffe or harvard, where she discovered that stars are made up of hydrogen and helium by analyzing spectra plates from the draper telescope in 1925. would be rehired as a computer assigned to leavitt's work on the harvard standard regions when she returned in 1934. = = references = = = = further reading = = sobel, dava ( 2016 ). the glass universe : how the ladies of the harvard observatory took the measure of the stars. new york, new york : viking. isbn 978 - 0670016952. von mertens, anna ( 2024 ). attention is discovery : the life and legacy of astronomer henrietta leavitt. cambridge, massachusetts : the mit press. isbn 978 - 0262049382. j. schechner, sara ; sliski, david ( 4 february 2016 ). " the scientific and historical value of annotations on astronomical photographic plates ". journal for the history of astronomy. 47 ( 1 ) : 3 β 29. arxiv : 1602. 03475. bibcode : 2016jha.... 47.... 3s. doi : 10. 1177 / 0021828615624094. eissn 1753 - 8556. zrull, lindsay smith ( 1 may 2021 ). " women in glass : women at the harvard observatory during the era of astronomical glass plate photography, 1875 β 1975 ". journal for the history of astronomy. 52 ( 2 ) : 115 β 146. bibcode : 2021jha.... 52.. 115z. doi : 10. 1177 / 00218286211000470. meghan, bartels ( 1 february 2017 ). " how harvard's vast collection of glass plates still shapes astronomy ". astronomy ( magazine ). retrieved 14 may 2025.
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averaged one - dependence estimators ( aode ) is a probabilistic classification learning technique. it was developed to address the attribute - independence problem of the popular naive bayes classifier. it frequently develops substantially more accurate classifiers than naive bayes at the cost of a modest increase in the amount of computation. = = the aode classifier = = aode seeks to estimate the probability of each class y given a specified set of features x1,... xn, p ( y | x1,... xn ). to do so it uses the formula p ^ ( y x 1, β¦ x n ) = i : 1 β€ i β€ n β§ f ( x i ) β₯ m p ^ ( y, x i ) j = 1 n p ^ ( x j y, x i ) y β² β y i : 1 β€ i β€ n β§ f ( x i ) β₯ m p ^ ( y β², x i ) j = 1 n p ^ ( x j y β², x i ) { \ displaystyle { \ hat { p } } ( y \ mid x _ { 1 }, \ ldots x _ { n } ) = { \ frac { \ sum _ { i : 1 \ leq i \ leq n \ wedge f ( x _ { i } ) \ geq m } { \ hat { p } } ( y, x _ { i } ) \ prod _ { j = 1 } ^ { n } { \ hat { p } } ( x _ { j } \ mid y, x _ { i } ) } { \ sum _ { y ^ { \ prime } \ in y } \ sum _ { i : 1 \ leq i \ leq n \ wedge f ( x _ { i } ) \ geq m } { \ hat { p } } ( y ^ { \ prime }, x _ { i } ) \ prod _ { j = 1 } ^ { n } { \ hat { p } } ( x _ { j } \ mid y ^ { \ prime }, x _ { i } ) } } } where p ^ ( β
) { \ displaystyle { \ hat { p } } ( \ cdot ) } denotes an estimate of p ( β
) { \ displaystyle p ( \ cdot ) }, f ( β
) { \ displaystyle f ( \ cdot ) } is the frequency
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\ hat { p } } ( \ cdot ) } denotes an estimate of p ( β
) { \ displaystyle p ( \ cdot ) }, f ( β
) { \ displaystyle f ( \ cdot ) } is the frequency with which the argument appears in the sample data and m is a user specified minimum frequency with which a term must appear in order to be used in the outer summation. in recent practice m is usually set at 1. = = derivation of the aode classifier = = we seek to estimate p ( y | x1,... xn ). by the definition of conditional probability p ( y x 1, β¦ x n ) = p ( y, x 1, β¦ x n ) p ( x 1, β¦ x n ). { \ displaystyle p ( y \ mid x _ { 1 }, \ ldots x _ { n } ) = { \ frac { p ( y, x _ { 1 }, \ ldots x _ { n } ) } { p ( x _ { 1 }, \ ldots x _ { n } ) } }. } for any 1 β€ i β€ n { \ displaystyle 1 \ leq i \ leq n }, p ( y, x 1, β¦ x n ) = p ( y, x i ) p ( x 1, β¦ x n y, x i ). { \ displaystyle p ( y, x _ { 1 }, \ ldots x _ { n } ) = p ( y, x _ { i } ) p ( x _ { 1 }, \ ldots x _ { n } \ mid y, x _ { i } ). } under an assumption that x1,... xn are independent given y and xi, it follows that p ( y, x 1, β¦ x n ) = p ( y, x i ) j = 1 n p ( x j y, x i ). { \ displaystyle p ( y, x _ { 1 }, \ ldots x _ { n } ) = p ( y, x _ { i } ) \ prod _ { j = 1 } ^ { n } p ( x _ { j } \ mid y, x _ { i } ). } this formula defines a special form of one dependence estimator ( ode ), a variant of the naive bayes classifier that makes the above independence assumption that is weaker ( and hence
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} \ mid y, x _ { i } ). } this formula defines a special form of one dependence estimator ( ode ), a variant of the naive bayes classifier that makes the above independence assumption that is weaker ( and hence potentially less harmful ) than the naive bayes'independence assumption. in consequence, each ode should create a less biased estimator than naive bayes. however, because the base probability estimates are each conditioned by two variables rather than one, they are formed from less data ( the training examples that satisfy both variables ) and hence are likely to have more variance. aode reduces this variance by averaging the estimates of all such odes. = = features of the aode classifier = = like naive bayes, aode does not perform model selection and does not use tuneable parameters. as a result, it has low variance. it supports incremental learning whereby the classifier can be updated efficiently with information from new examples as they become available. it predicts class probabilities rather than simply predicting a single class, allowing the user to determine the confidence with which each classification can be made. its probabilistic model can directly handle situations where some data are missing. aode has computational complexity o ( l n 2 ) { \ displaystyle o ( ln ^ { 2 } ) } at training time and o ( k n 2 ) { \ displaystyle o ( kn ^ { 2 } ) } at classification time, where n is the number of features, l is the number of training examples and k is the number of classes. this makes it infeasible for application to high - dimensional data. however, within that limitation, it is linear with respect to the number of training examples and hence can efficiently process large numbers of training examples. = = implementations = = the free weka machine learning suite includes an implementation of aode. = = see also = = cluster - weighted modeling = = references = =
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environmental geology, like hydrogeology, is an applied science concerned with the practical application of the principles of geology in the solving of environmental problems created by man. it is a multidisciplinary field that is closely related to engineering geology and, to a lesser extent, to environmental geography. each of these fields involves the study of the interaction of humans with the geologic environment, including the biosphere, the lithosphere, the hydrosphere, and to some extent the atmosphere. in other words, environmental geology is the application of geological information to solve conflicts, minimizing possible adverse environmental degradation, or maximizing possible advantageous conditions resulting from the use of natural and modified environment. with an increasing world population and industrialization, the natural environment and resources are under high strain which puts them at the forefront of world issues. environmental geology is on the rise with these issues as solutions are found by utilizing it. = = environmental geology in relation to other fields = = = = = hydrogeology = = = hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the earth's crust. environmental geology is applied in this field as environmental problems are created in groundwater pollution due to mining, agriculture, and other human activities. pollution is the impairment of groundwater by heat, bacteria, or chemicals. the greatest contributors to groundwater pollution are surface sources such as fertilizers, leaking sewers, polluted streams, and mining / mineral wastes. environmental geology approaches the groundwater pollution problem by creating objectives when monitoring. these objectives include : determining the nature, extent, and degree of contamination, determining the propagation mechanism and hydrological parameters, so that the appropriate countermeasures can be taken, detecting and warning of movement into critical areas, assessing the effectiveness of the immediate countermeasures undertaken to offset the effects of contamination, recording of data for long term evaluation and compliance with standards, and initiating research monitoring to validate and verify the models and assumptions upon which the immediate countermeasures are based. = = = soil science = = = soil science is the study of soil as a natural resource on the surface of the earth. environmental geology is applied in this field as soil scientists raise concerns on soil preservation and arable land with the world increasing population, increasing per capita food consumption, and land degradation. these environmental problems are attacked and reduced with environmental geology by using soil surveys. these surveys assess the properties of soils and are of use in geologic mapping, rural and urban land
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with the world increasing population, increasing per capita food consumption, and land degradation. these environmental problems are attacked and reduced with environmental geology by using soil surveys. these surveys assess the properties of soils and are of use in geologic mapping, rural and urban land planning, especially in terms of agriculture and forestry. soil surveys are essential parts of land use planning and mapping as they provide insight on agricultural land usage. soil surveys provide information on optimum cropping systems and soil management so less land degradation is done and agriculture provides its optimum yield for the increasing per capita food consumption. soil survey investigations include : soil erodibility, depth of soil, steepness of slope, shrink - swell potential, frequency of rock outcrops, possibility of salinization fertilizer - plant response, and crop variety trials. = = focuses = = environmental geology includes managing geological and hydrogeological resources such as fossil fuels, minerals, water ( surface and groundwater ), and land use, studying the earth's surface through the disciplines of geomorphology, and edaphology, defining and mitigating exposure of natural hazards on humans, managing industrial and domestic waste disposal and minimizing or eliminating effects of pollution, and performing associated activities, often involving litigation. environmental geology is often applied to some well known environmental issues including population growth, mining, diminishing resources, and global land use. = = = mining = = = since the stone age, when humans began mining for flint, they have been dependent on this practice, and the dependency on minerals continues to increase as society evolves. one of the downsides of mining is that it is restricted to areas where minerals are present and economically viable. mining duration is also restrained as mineral resources are finite, so when a deposit is exhausted, mining in that location comes to an end. although modern mining and mineral activities utilize many ways to reduce negative environmental impacts, accidental releases can occur and the appropriate mitigation and prevention practices were not common in historical practices. potentially harmful metals, other deposit constituents, and mineral processing chemicals or byproducts can contaminate the surrounding environment due to these situations. some common environmental impacts of mining are rock displacements that allow fine dust particles to seep into surface waters, the defacement of the local landscape, and the large amounts of waste with some being chemically reactive. ultimately, the impact that mining has on the environment is determined by many factors such as the size of the operation and the type of mining. environmental geology has reduced the negative
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local landscape, and the large amounts of waste with some being chemically reactive. ultimately, the impact that mining has on the environment is determined by many factors such as the size of the operation and the type of mining. environmental geology has reduced the negative environmental impacts of mining as it has been used in litigation toward mining. in some countries like brazil and australia for example, it is decreed by law that sites must undergo rehabilitation after a mining operation has ceased. prior to any mining, an assessment is also necessary to analyze the potential environmental impacts. another measure taken is that an environmental management program must be produced to show how the mine will operate. land planning is an important aspect in deciding whether a site is suitable for mining but some environmental degradation is inevitable. environmental geology continues to lower the amount of negative effects that mining has on the natural environment. = = = recycling = = = nonrenewable resources are only one type of resource with the other two being potentially renewable and perpetual. nonrenewable resources, such as fossil fuels and metals, are finite, and therefore cannot be replenished during human lifetime, but are being depleted at a high rate. due to their importance in many economies, this creates an issue as the world keeps developing the technologies used to exploit these resources. some important roles of these nonrenewable resources are to heat homes, fuel cars, and build infrastructure. environmental geology has been used to approach this issue with the sustainable development of recycling and reusing. recycling is the process of collecting recyclable consumer and industrial materials and products and then sorting them so they can be processed into raw materials with the intention of then using the raw materials to create new products. recycling and reusing can be done on an individual scale as well as an industrial scale. these practices maximize the usage of resources as much as possible all while minimizing waste. they also manage the industrial and domestic waste disposal as they reduce the amount of waste discharged into the global environment. reusing and recycling include : composting : the biological decomposition of organic garden and food waste in order to use it as soil conditioner, upcycling : increasing the value and quality in materials and products through the recycling process, freecycling : giving or getting free items from others before buying new ones industrial ecology : dismantling of massive artifacts to become input for new processes environmental geology's approach to the decline of nonrenewable resources along with high amounts of waste polluting the earth has been to reduce wasteful usage and recycle
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industrial ecology : dismantling of massive artifacts to become input for new processes environmental geology's approach to the decline of nonrenewable resources along with high amounts of waste polluting the earth has been to reduce wasteful usage and recycle when possible. = = = land use = = = planning out the usage of land is important to reduce the risk of natural hazards on humans and their infrastructure, but mostly to reduce negative human impact on the natural environment. the land, water, air, materials, and energy use are all critically impacted by human settlement and resource production. new sites must be found for mining, waste disposal, and industrial sites as these are all parts of an industrial society. suitable sites are often difficult to find and get approval for as they must be shown to have barriers so contaminants are prevented from entering the environment. site investigation in land use planning often includes at least two phases, an orientating investigation and a detailed investigation. the information in an orientating investigation is obtained through maps and other archived data. the information in a detailed investigation is obtained through a reconnaissance survey in the field and by reviewing the historic land use. the orientating investigation includes : topography, land use and vegetation, settlements, roads and railways, climate : precipitation, temperature, evapotranspiration, direction and the velocity of the wind, as well as the frequency of strong winds, hydrological and hydrogeological conditions : streams, lakes and ponds, springs, wells, use and quality of surface and groundwater, runoff, water balance, aquifer / aquiclude properties and stratigraphy, groundwater table, groundwater recharge and discharge, geology : soil, geological structures, stratigraphy and lithology, ecological aspects : e. g., nature reserves, protected geotopes, water protection areas. the detailed investigation includes : geology : thickness and lateral extent of strata and geological units, lithology, homogeneity and heterogeneity, bedding conditions and tectonic structures, fractures, impact of weathering, groundwater : water table, water content, direction and rate of groundwater flow, hydraulic conductivity, value of aquifer, geochemical site characterization : chemical composition of soil, rocks and groundwater, estimation of contamination retention, geotechnical stability : the geological barrier must be capable of adsorbing strain from the weight of a landfill, slag heap, or industrial building. geogenic events : active faults, karst, earthquakes, subsidence, landslide
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retention, geotechnical stability : the geological barrier must be capable of adsorbing strain from the weight of a landfill, slag heap, or industrial building. geogenic events : active faults, karst, earthquakes, subsidence, landslides, anthropogenic activities : mining damage, buildings, quarries, gravel pits, etc., and changes in soil and groundwater quality environmental geology includes both the monitorization and planning of land use. land use maps are made to represent current land use along with possible future uses. land maps like the one shown can be used to reduce human settlement in areas with potential natural hazards such as floods, geological instability, wildfires, etc. in the land map shown it can be seen that there is a margin of trees and vegetation between the settlements and mississippi river to reduce the risk of flood damage as the mississippi rivers water levels change. = = further reading = = some books and peer - reviewed journals in the field are : environmental earth sciences ( issn 1866 - 6280 ), formerly environmental geology ( issn 0943 - 0105 ), environmental geology ( isbn 9781493987870 ), and investigations in environmental geology ( isbn 9780131420649 ) = = see also = = anthropocene economic geology environmental soil science integrated geography soil contamination water pollution = = references = = = = external links = = us department of labor
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the transmission curve or transmission characteristic is the mathematical function or graph that describes the transmission fraction of an optical or electronic filter as a function of frequency or wavelength. it is an instance of a transfer function but, unlike the case of, for example, an amplifier, output never exceeds input ( maximum transmission is 100 % ). the term is often used in commerce, science, and technology to characterise filters. the term has also long been used in fields such as geophysics and astronomy to characterise the properties of regions through which radiation passes, such as the ionosphere. = = see also = = electronic filter β examples of transmission characteristics of electronic filters = = references = =
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in the mathematical area of topology, a train track is a family of curves embedded on a surface, meeting the following conditions : the curves meet at a finite set of vertices called switches. away from the switches, the curves are smooth and do not touch each other. at each switch, three curves meet with the same tangent line, with two curves entering from one direction and one from the other. the main application of train tracks in mathematics is to study laminations of surfaces, that is, partitions of closed subsets of surfaces into unions of smooth curves. train tracks have also been used in graph drawing. = = train tracks and laminations = = a lamination of a surface is a partition of a closed subset of the surface into smooth curves. the study of train tracks was originally motivated by the following observation : if a generic lamination on a surface is looked at from a distance by a myopic person, it will look like a train track. a switch in a train track models a point where two families of parallel curves in the lamination merge to become a single family, as shown in the illustration. although the switch consists of three curves ending in and intersecting at a single point, the curves in the lamination do not have endpoints and do not intersect each other. for this application of train tracks to laminations, it is often important to constrain the shapes that can be formed by connected components of the surface between the curves of the track. for instance, penner and harer require that each such component, when glued to a copy of itself along its boundary to form a smooth surface with cusps, have negative cusped euler characteristic. a train track with weights, or weighted train track or measured train track, consists of a train track with a non - negative real number, called a weight, assigned to each branch. the weights can be used to model which of the curves in a parallel family of curves from a lamination are split to which sides of the switch. weights must satisfy the following switch condition : the weight assigned to the ingoing branch at a switch should equal the sum of the weights assigned to the branches outgoing from that switch. weights are closely related to the notion of carrying. a train track is said to carry a lamination if there is a train track neighborhood such that every leaf of the lamination is contained in the neighborhood and intersects each vertical fiber transversely. if each vertical fiber has nontrivial intersection with some leaf, then the lamination is fully carried by
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##ination if there is a train track neighborhood such that every leaf of the lamination is contained in the neighborhood and intersects each vertical fiber transversely. if each vertical fiber has nontrivial intersection with some leaf, then the lamination is fully carried by the train track. = = references = = penner, r. c., with harer, j. l. ( 1992 ). combinatorics of train tracks. princeton university press, annals of mathematics studies. isbn 0 - 691 - 02531 - 2. { { cite book } } : cs1 maint : multiple names : authors list ( link )
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magnetic - activated cell sorting ( macs ) is a method for separation of various cell populations depending on their surface antigens ( cd molecules ) invented by miltenyi biotec. the name macs is a registered trademark of the company. the method was developed with miltenyi biotec's macs system, which uses superparamagnetic nanoparticles and columns. the superparamagnetic nanoparticles are of the order of 100 nm. they are used to tag the targeted cells in order to capture them inside the column. the column is placed between permanent magnets so that when the magnetic particle - cell complex passes through it, the tagged cells can be captured. the column consists of steel wool which increases the magnetic field gradient to maximize separation efficiency when the column is placed between the permanent magnets. magnetic - activated cell sorting is a commonly used method in areas like immunology, cancer research, neuroscience, and stem cell research. miltenyi sells microbeads which are magnetic nanoparticles conjugated to antibodies which can be used to target specific cells. in the assisted reproductive technology ( art ) field, the apoptotic spermatozoa ( those who are programmed to die ) are bind in the annexin v ( a membrane apoptotic marker ) with a specific monoclonal antibodies which are conjugated a magnetic microsphere. so later when we use a macs column it is possible to separate the healthy spermatozoa with the apoptotic ones. = = procedure = = the macs method allows cells to be separated by using magnetic nanoparticles coated with antibodies against a particular surface antigen. this causes the cells expressing this antigen to attach to the magnetic nanoparticles. after incubating the beads and cells, the solution is transferred to a column in a strong magnetic field. in this step, the cells attached to the nanoparticles ( expressing the antigen ) stay on the column, while other cells ( not expressing the antigen ) flow through. with this method, the cells can be separated positively or negatively with respect to the particular antigen ( s ). = = = positive and negative selection = = = with positive selection, the cells expressing the antigen ( s ) of interest, which attached to the magnetic column, are washed out to a separate vessel, after removing the column from the magnetic field. this method is useful for isolation of a particular cell type, for instance cd4 lymphocytes. moreover, it enables
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, which attached to the magnetic column, are washed out to a separate vessel, after removing the column from the magnetic field. this method is useful for isolation of a particular cell type, for instance cd4 lymphocytes. moreover, it enables early detection of sperm which initiate apoptosis, although they may show an adequate appearance and motility. a magnetic - labelled receptor that binds to annexin is added to sperm. inside normal cells, phosphatidylserine molecules are located within the cell membrane towards the cytoplasm. nevertheless, in those cells that initiate the apoptotic process phosphatidylserine instead faces the cell membrane outer side, binding to the annexin conjugate. therefore, normal spermatozoa will pass through the column without binding to the labelled receptor. on the other hand, proapoptotic sperm will remain trapped, which turns out as a sperm selection process thanks to the magnetic - labeled antibody. finally, this technique has shown its efficacy, even though it remains limited. with negative selection, the antibody used is against surface antigen ( s ) which are known to be present on cells that are not of interest. after administration of the cells / magnetic nanoparticles solution onto the column the cells expressing these antigens bind to the column and the fraction that goes through is collected, as it contains almost no cells with these undesired antigens. = = modifications = = magnetic nanoparticles conjugated to an antibody against an antigen of interest are not always available, but there is a way to circumvent it. since fluorophore - conjugated antibodies are much more prevalent, it is possible to use magnetic nanoparticles coated with anti - fluorochrome antibodies. they are incubated with the fluorescent - labelled antibodies against the antigen of interest and may thus serve for cell separation with respect to the antigen. = = see also = = dynabeads flow cytometry = = references = = s. miltenyi, w. muller, w. weichel, and a. radbruch, β high gradient magnetic cell separation with macs, β cytometry, vol. 11, no. 2, pp. 231 β 238, 1990.
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dialysis tubing, also known as visking tubing, is an artificial semi - permeable membrane tubing used in separation techniques, that facilitates the flow of tiny molecules in solution based on differential diffusion. in the context of life science research, dialysis tubing is typically used in the sample clean - up and processing of proteins and dna samples or complex biological samples such as blood or serums. dialysis tubing is also frequently used as a teaching aid to demonstrate the principles of diffusion, osmosis, brownian motion and the movement of molecules across a restrictive membrane. for the principles and usage of dialysis in a research setting, see dialysis ( chemistry ). = = history, properties and composition = = dialysis occurs throughout nature and the principles of dialysis have been exploited by humans for thousands of years using natural animal or plant - based membranes. the term dialysis was first routinely used for scientific or medical purposes in the late 1800s and early 1900s, pioneered by the work of thomas graham. the first mass - produced man - made membranes suitable for dialysis were not available until the 1930s, based on materials used in the food packaging industry such as cellophane. in the 1940s, willem kolff constructed the first dialyzer ( artificial kidney ), and successfully treated patients with kidney failure using dialysis across semi - permeable membranes. today, dialysis tubing for laboratory applications comes in a variety of dimensions and molecular - weight cutoffs ( mwco ). in addition to tubing, dialysis membranes are also found in a wide range of different preformatted devices, significantly improving the performance and ease of use of dialysis. different dialysis tubing or flat membranes are produced and characterized as differing molecular - weight cutoffs ( mwco ) ranging from 1 β 1, 000, 000 kda. the mwco determination is the result of the number and average size of the pores created during the production of the dialysis membrane. the mwco typically refers to the smallest average molecular mass of a standard molecule that will not effectively diffuse across the membrane upon extended dialysis. thus, a dialysis membrane with a 10k mwco will generally retain > 90 % of a protein having a molecular mass of at least 10 kda. pore sizes typically range from ~ 10 β 100 angstroms for 1k to 50k mwco membranes. it is important to note that the mwco of a membrane is not a sharply defined value. molecules with mass near the mwco of
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pore sizes typically range from ~ 10 β 100 angstroms for 1k to 50k mwco membranes. it is important to note that the mwco of a membrane is not a sharply defined value. molecules with mass near the mwco of the membrane will diffuse across the membrane slower than molecules significantly smaller than the mwco. in order for a molecule to rapidly diffuse across a membrane, it typically needs to be at least 20 β 50 times smaller than the membranes mwco rating. therefore, it is not practical to try separating a 30kda protein from a 10kda protein using dialysis across a 20k rated dialysis membrane. dialysis tubing for laboratory use is typically made of a film of regenerated cellulose or cellulose ester. however ; dialysis membranes made of polysulfone, polyethersulfone ( pes ), etched polycarbonate, or collagen are also extensively used for specific medical, food, or water treatment applications. = = manufacturing = = membranes, composed of either regenerated cellulose or cellulose esters, are manufactured through distinct processes of modifying and cross - linking cellulose fibers ( derived from wood pulp or cotton fibers ) to form films with differing properties and pore sizes. variations in the manufacturing process significantly change the properties and pore sizes of the films ; depending on the cross - linkages introduced in cellulose, the size of pores can be modulated. while similar in composition, most of the cellulose - based membranes currently manufactured are not necessarily useful for dialysis. cellulose - based membranes are also widely used for applications ranging from food wrapping, film stock, or β plastic β wrap. for dialysis applications, regenerated cellulose - based membranes are extruded as tubing or sheets and then dried. glycerol is frequently added as a humectant to prevent cracking during drying and to help maintain the desired pore structure. regenerated cellulose membranes are very hydrophilic and hydrate rapidly when introduced to water. due to their additional crosslinking, regenerated cellulose membranes have better chemical compatibility and heat stability than membranes made from cellulose esters. regenerated cellulose membranes are more resistant to organic solvents and to the weak or dilute acids and bases that are commonly used in protein and molecular biology applications. membranes based on cellulose esters are typically supplied wet and come in a greater range of
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##ulose membranes are more resistant to organic solvents and to the weak or dilute acids and bases that are commonly used in protein and molecular biology applications. membranes based on cellulose esters are typically supplied wet and come in a greater range of mwcos. pore sizes are typically more consistent across cellulose acetate membranes. = = references = =
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in statistics and regression analysis, moderation ( also known as effect modification ) occurs when the relationship between two variables depends on a third variable. the third variable is referred to as the moderator variable ( or effect modifier ) or simply the moderator ( or modifier ). the effect of a moderating variable is characterized statistically as an interaction ; that is, a categorical ( e. g., sex, ethnicity, class ) or continuous ( e. g., age, level of reward ) variable that is associated with the direction and / or magnitude of the relation between dependent and independent variables. specifically within a correlational analysis framework, a moderator is a third variable that affects the zero - order correlation between two other variables, or the value of the slope of the dependent variable on the independent variable. in analysis of variance ( anova ) terms, a basic moderator effect can be represented as an interaction between a focal independent variable and a factor that specifies the appropriate conditions for its operation. = = example = = moderation analysis in the behavioral sciences involves the use of linear multiple regression analysis or causal modelling. to quantify the effect of a moderating variable in multiple regression analyses, regressing random variable y on x, an additional term is added to the model. this term is the interaction between x and the proposed moderating variable. thus, for a response y and two variables : x1 and moderating variable x2, : y = b 0 + b 1 x 1 + b 2 x 2 + b 3 ( x 1 Γ x 2 ) + Ξ΅ { \ displaystyle y = b _ { 0 } + b _ { 1 } x _ { 1 } + b _ { 2 } x _ { 2 } + b _ { 3 } ( x _ { 1 } \ times x _ { 2 } ) + \ varepsilon \, } in this case, the role of x2 as a moderating variable is accomplished by evaluating b3, the parameter estimate for the interaction term. see linear regression for discussion of statistical evaluation of parameter estimates in regression analyses. = = multicollinearity in moderated regression = = in moderated regression analysis, a new interaction predictor ( x 1 x 2 { \ displaystyle x _ { 1 } x _ { 2 } } ) is calculated. however, the new interaction term may be correlated with the two main effects terms used to calculate it. this is the problem of multicollinearity in moderated regression. multicollinearity tends
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_ { 2 } } ) is calculated. however, the new interaction term may be correlated with the two main effects terms used to calculate it. this is the problem of multicollinearity in moderated regression. multicollinearity tends to cause coefficients to be estimated with higher standard errors and hence greater uncertainty. mean - centering ( subtracting raw scores from the mean ) may reduce multicollinearity, resulting in more interpretable regression coefficients. however, it does not affect the overall model fit. = = post - hoc probing of interactions = = like simple main effect analysis in anova, in post - hoc probing of interactions in regression, we are examining the simple slope of one independent variable at the specific values of the other independent variable. below is an example of probing two - way interactions. in what follows, the regression equation with two variables a and b and an interaction term a * b, y = b 0 + b 1 a + b 2 b + b 3 a β b + Ξ΅ { \ displaystyle y = b _ { 0 } + b _ { 1 } a + b _ { 2 } b + b _ { 3 } a * b + \ varepsilon } will be considered. = = = two categorical independent variables = = = if both of the independent variables are categorical variables, we can analyze the results of the regression for one independent variable at a specific level of the other independent variable. for example, suppose that both a and b are single dummy coded ( 0, 1 ) variables, and that a represents ethnicity ( 0 = european americans, 1 = east asians ) and b represents the condition in the study ( 0 = control, 1 = experimental ). then the interaction effect shows whether the effect of condition on the dependent variable y is different for european americans and east asians and whether the effect of ethnic status is different for the two conditions. the coefficient of a shows the ethnicity effect on y for the control condition, while the coefficient of b shows the effect of imposing the experimental condition for european american participants. to probe if there is any significant difference between european americans and east asians in the experimental condition, we can simply run the analysis with the condition variable reverse - coded ( 0 = experimental, 1 = control ), so that the coefficient for ethnicity represents the ethnicity effect on y in the experimental condition. in a similar vein, if we want to see whether the treatment has an effect for east asian participants, we can reverse code the ethnicity variable ( 0
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control ), so that the coefficient for ethnicity represents the ethnicity effect on y in the experimental condition. in a similar vein, if we want to see whether the treatment has an effect for east asian participants, we can reverse code the ethnicity variable ( 0 = east asians, 1 = european americans ). = = = one categorical and one continuous independent variable = = = if the first independent variable is a categorical variable ( e. g. gender ) and the second is a continuous variable ( e. g. scores on the satisfaction with life scale ( swls ) ), then b1 represents the difference in the dependent variable between males and females when life satisfaction is zero. however, a zero score on the satisfaction with life scale is meaningless as the range of the score is from 7 to 35. this is where centering comes in. if we subtract the mean of the swls score for the sample from each participant's score, the mean of the resulting centered swls score is zero. when the analysis is run again, b1 now represents the difference between males and females at the mean level of the swls score of the sample. cohen et al. ( 2003 ) recommended using the following to probe the simple effect of gender on the dependent variable ( y ) at three levels of the continuous independent variable : high ( one standard deviation above the mean ), moderate ( at the mean ), and low ( one standard deviation below the mean ). if the scores of the continuous variable are not standardized, one can just calculate these three values by adding or subtracting one standard deviation of the original scores ; if the scores of the continuous variable are standardized, one can calculate the three values as follows : high = the standardized score minus 1, moderate ( mean = 0 ), low = the standardized score plus 1. then one can explore the effects of gender on the dependent variable ( y ) at high, moderate, and low levels of the swls score. as with two categorical independent variables, b2 represents the effect of the swls score on the dependent variable for females. by reverse coding the gender variable, one can get the effect of the swls score on the dependent variable for males. = = = = coding in moderated regression = = = = when treating categorical variables such as ethnic groups and experimental treatments as independent variables in moderated regression, one needs to code the variables so that each code variable represents a specific setting of the categorical variable. there are three basic ways of coding : dummy - variable coding
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##egorical variables such as ethnic groups and experimental treatments as independent variables in moderated regression, one needs to code the variables so that each code variable represents a specific setting of the categorical variable. there are three basic ways of coding : dummy - variable coding, contrast coding and effects coding. below is an introduction to these coding systems. dummy coding compares a reference group ( one specific condition such as a control group in the experiment ) with each of the other experimental groups. in this case, the intercept b 0 = y reference { \ displaystyle b _ { 0 } = { \ bar { y } } _ { \ text { reference } } } is the mean of the reference group. each unstandardized regression coefficient b a = y a β y reference { \ displaystyle b _ { a } = { \ bar { y } } _ { a } - { \ bar { y } } _ { \ text { reference } } } is the difference in the dependent variable mean between a treatment group and the reference group. this coding system is similar to anova analysis. contrast coding investigates a series of orthogonal contrasts ( group comparisons ). the intercept b 0 = y 1 β¦ n { \ displaystyle b _ { 0 } = { \ overline { { \ bar { y } } _ { 1 \ dots n } } } } is the unweighted mean of the individual group means. the unstandardized regression coefficient b a, b = y b β y a { \ displaystyle b _ { a, b } = { \ bar { y } } _ { b } - { \ bar { y } } _ { a } } represents the difference between two groups. this coding system is appropriate when researchers have an a priori hypothesis concerning the specific differences among the group means. effects coding is used when there is no reference group or orthogonal contrasts. the intercept b 0 { \ displaystyle b _ { 0 } } is the grand mean ( the mean of all the conditions ). the regression coefficient b a = y a β y 1 β¦ n { \ displaystyle b _ { a } = { \ bar { y } } _ { a } - { \ overline { { \ bar { y } } _ { 1 \ dots n } } } } is the difference between one group mean and the mean of all the group means. this coding system is appropriate when the groups represent natural categories. = = = two continuous independent variables = = =
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Moderation (statistics)
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wikipedia
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} } _ { 1 \ dots n } } } } is the difference between one group mean and the mean of all the group means. this coding system is appropriate when the groups represent natural categories. = = = two continuous independent variables = = = if both of the independent variables are continuous, it is helpful for interpretation to either center or standardize the independent variables, x and z. ( centering involves subtracting the overall sample mean score from the original score ; standardizing does the same followed by dividing by the overall sample standard deviation. ) by centering or standardizing the independent variables, the coefficient of x or z can be interpreted as the effect of that variable on y at the mean level of the other independent variable. to probe the interaction effect, it is often helpful to plot the effect of x on y at low and high values of z ( some people prefer to also plot the effect at moderate values of z, but this is not necessary ). often values of z that are one standard deviation above and below the mean are chosen for this, but any sensible values can be used ( and in some cases there are more meaningful values to choose ). the plot is usually drawn by evaluating the values of y for high and low values of both x and z, and creating two lines to represent the effect of x on y at the two values of z. sometimes this is supplemented by simple slope analysis, which determines whether the effect of x on y is statistically significant at particular values of z. a common technique for simple slope analysis is the johnson - neyman approach. various internet - based tools exist to help researchers plot and interpret such two - way interactions. = = = higher - level interactions = = = the principles for two - way interactions apply when we want to explore three - way or higher - level interactions. for instance, if we have a three - way interaction between a, b, and c, the regression equation will be as follows : y = b 0 + b 1 a + b 2 b + b 3 c + b 4 a β
b + b 5 a β
c + b 6 b β
c + b 7 a β
b β
c + Ξ΅. { \ displaystyle y = b _ { 0 } + b _ { 1 } a + b _ { 2 } b + b _ { 3 } c + b _ { 4 } a \ cdot b + b _ { 5 } a \ cdot c + b _ { 6 } b \ cdot c + b _ { 7 }
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Moderation (statistics)
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wikipedia
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{ 2 } b + b _ { 3 } c + b _ { 4 } a \ cdot b + b _ { 5 } a \ cdot c + b _ { 6 } b \ cdot c + b _ { 7 } a \ cdot b \ cdot c + \ varepsilon. } = = = spurious higher - order effects = = = it is worth noting that the reliability of the higher - order terms depends on the reliability of the lower - order terms. for example, if the reliability for variable a is 0. 70, the reliability for variable b is 0. 80, and their correlation is r = 0. 2, then the reliability for the interaction variable a * b is ( ( 0. 7 Γ 0. 8 ) + 0. 2 2 ) / ( 1 + 0. 2 2 ) = 0. 577 { \ displaystyle ( ( 0. 7 \ times 0. 8 ) + 0. 2 ^ { 2 } ) / ( 1 + 0. 2 ^ { 2 } ) = 0. 577 }. in this case, low reliability of the interaction term leads to low power ; therefore, we may not be able to find the interaction effects between a and b that actually exist. the solution for this problem is to use highly reliable measures for each independent variable. another caveat for interpreting the interaction effects is that when variable a and variable b are highly correlated, then the a * b term will be highly correlated with the omitted variable a2 ; consequently what appears to be a significant moderation effect might actually be a significant nonlinear effect of a alone. if this is the case, it is worth testing a nonlinear regression model by adding nonlinear terms in individual variables into the moderated regression analysis to see if the interactions remain significant. if the interaction effect a * b is still significant, we will be more confident in saying that there is indeed a moderation effect ; however, if the interaction effect is no longer significant after adding the nonlinear term, we will be less certain about the existence of a moderation effect and the nonlinear model will be preferred because it is more parsimonious. moderated regression analyses also tend to include additional variables, which are conceptualized as covariates of no interest. however, the presence of these covariates can induce spurious effects when either ( 1 ) the covariate ( c ) is correlated with one of the primary variables of interest ( e. g. variable a or b ), or ( 2 )
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Moderation (statistics)
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wikipedia
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