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Bray–Curtis Dissimilarity
In ecology and biology, the Bray–Curtis dissimilarity is a statistic used to quantify the dissimilarity in species composition between two different sites, based on counts at each site. It is named after J. Roger Bray and John T. Curtis who first presented it in a paper in 1957. The Bray-Curtis dissimilarity BC_ between two sites j and k is : BC_ = 1 - \frac = 1 - \frac where N_ is the number of specimens of species i at site j, N_ is the number of specimens of species i at site k, and p the total number of species in the samples. In the alternative shorthand notation C_ is the sum of the lesser counts of each species. S_j and S_k are the total number of specimens counted at both sites. The index can be simplified to 1-2C/2 = 1-C when the abundances at each site are expressed as proportions, though the two forms of the equation only produce matching results when the total number of specimens counted at both sites are the same. Further treatment can be found in Legend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology, and natural history. Ecology is a branch of biology, and it is not synonymous with environmentalism. Among other things, ecology is the study of: * The abundance, biomass, and distribution of organisms in the context of the environment * Life processes, antifragility, interactions, and adaptations * The movement of materials and energy through living communities * The successional development of ecosystems * Cooperation, competition, and predation within and between species * Patterns of biodiversity and its effect on ecosystem processes Ecology has practical applications in conservation biology, wetland management, natural resource managemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments. Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations.Based on definition from: Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use. Like other scientists, biologists use the sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Thomas Curtis
John Thomas Curtis (September 20, 1913 – June 7, 1961) was an American botanist and plant ecologist. He is particularly known for his lasting contribution to the development of numerical methods in ecology. Together with J. Roger Bray, he developed the method of polar ordination (now known as Bray-Curtis ordination) with its inherent distance measure, the Bray-Curtis dissimilarity. Curtis completed his Ph.D. in botany at the University of Wisconsin in 1937. He remained affiliated with that university for the remainder of his career, except through 1942–1945, when he served as research director of the Société Haïtiano-Américaine de Développement Agricole. Both in 1942 and in 1956, he was awarded Guggenheim Fellowships. In 1951 he was made full professor of botany at the University of Wisconsin. The collective efforts of Curtis and the thirty-nine Ph.D. students that he managed to supervise during his relatively short career, resulted in the work ‘’’The Vegetati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elsevier
Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell'', the ScienceDirect collection of electronic journals, '' Trends'', the '' Current Opinion'' series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services also include digital tools for data management, instruction, research analytics and assessment. Elsevier is part of the RELX Group (known until 2015 as Reed Elsevier), a publicly traded company. According to RELX reports, in 2021 Elsevier published more than 600,000 articles annually in over 2,700 journals; as of 2018 its archives contained over 17 million documents and 40,000 e-books, with over one billion annual downloads. Researchers have criticized Elsevier for its high profit marg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sørensen Similarity Index
Sørensen () is a Danish-Norwegian patronymic surname meaning "son of Søren" (given name equivalent of Severin). , it is the eighth most common surname in Denmark. Immigrants to English-speaking countries often changed the spelling to ''Sorensen'' or ''Sorenson'' in order to accommodate English orthographic rules. English-language media often similarly renders ''Sørensen'' as either ''Sorensen'' or ''Sorenson''. A parallel form of similar origin is Severinsen. The numbers of bearers of the surnames ''Sørensen'' and ''Severinsen'' in Denmark and Norway (2008): It may refer to a number of people: People with the same name * Ole Sørensen * Peter Sørensen In sports * Aksel Sørensen (1891-1955), Danish gymnast * Andreas Sørensen (born 1984), Danish footballer * Arne Sørensen (1917-1977), Danish footballer and manager *Asger Sørensen (born 1996), Danish footballer *Chris Sørensen (born 1977), Danish footballer *Chris Anker Sørensen (1984-2021), Danish cyclist *Dennis Søre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triangle Inequality
In mathematics, the triangle inequality states that for any triangle, the sum of the lengths of any two sides must be greater than or equal to the length of the remaining side. This statement permits the inclusion of degenerate triangles, but some authors, especially those writing about elementary geometry, will exclude this possibility, thus leaving out the possibility of equality. If , , and are the lengths of the sides of the triangle, with no side being greater than , then the triangle inequality states that :z \leq x + y , with equality only in the degenerate case of a triangle with zero area. In Euclidean geometry and some other geometries, the triangle inequality is a theorem about distances, and it is written using vectors and vector lengths ( norms): :\, \mathbf x + \mathbf y\, \leq \, \mathbf x\, + \, \mathbf y\, , where the length of the third side has been replaced by the vector sum . When and are real numbers, they can be viewed as vectors in , and the trian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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