|
Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity in a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, size, weight, height, distribution, texture, language, income, disease, temperature, radioactivity, architectural design, etc.); one that is heterogeneous is distinctly nonuniform in one of these qualities.〔 Heterogeneous Mixtures, in chemistry, is where certain elements are unwillingly combined and, when given the option, will separates completely. 〕〔〔 The words homogeneous and heterogeneous come from Medieval Latin ''homogeneus'' and ''heterogeneus'', from Ancient Greek ὁμογενής (''homogenēs'') and ἑτερογενής (''heterogenēs''), from ὁμός (''homos'', “same”) and ἕτερος (''heteros'', “other, another, different”) respectively, followed by γένος (''genos'', “kind”); -ous is an adjectival suffix.〔http://www.oxforddictionaries.com/definition/english/heterogeneous〕 The concepts are the same to every level of complexity, from atoms to populations of animals or people, and galaxies. Hence, an element may be homogeneous on a larger scale, compared to being heterogeneous on a smaller scale. This is known as an effective medium approach, or effective medium approximations.〔 Google Books preview download available〕 ==Heterogeneity== Heterogeneity is the state of being heterogeneous. It is the nature of opposition, or contrariety of qualities. It is diverse in kind or nature; composed of diverse parts, or resulting from differing causes. In general, a heterogeneous entity is composed of dissimilar parts, hence the constituents are of a different kind that can be distinguished from one another. The parts (or constituents) are connected, and of a conglomerate mass, and viewed in respect to the parts of which it is made up.〔 〕〔 Heterogeneous Mixtures, in chemistry, is where certain elements are unwillingly combined and, when given the option, will separate. 〕 Various disciplines understand ''heterogeneity'', or being ''heterogeneous'', in different ways. For example: *In physics, it is understood as having physical properties that vary within the medium. For more information, please refer to article Homogeneity (physics). *In chemistry, a heterogeneous material consists of either or both of a) multiple states of matter or b) hydrophilic and hydrophobic substances in one mixture; an example of the latter would be a mixture of water, octane, and silicone grease. Heterogeneous solids, liquids, and gases may be made homogeneous by melting, stirring, or by allowing time to pass for diffusion to distribute the molecules evenly. For example adding dye to water will create a heterogeneous solution at first, but will become homogeneous over time. Entropy allows for heterogeneous substances to become homogeneous over time. *With information technology (see: Heterogeneous computing) it means a network comprising different types of computers, potentially with vastly differing memory sizes, processing power and even basic underlying architecture. Alternatively, a data resource with multiple types of formats.. *In sociology it may refer to a society or group that includes individuals of differing ethnicities, cultural backgrounds, sexes, or ages. *Earth is a heterogeneous substance in many aspects. e.g. Rocks (geology) are inherently heterogeneous, usually occurring at the micro-scale and mini-scale.〔 Subsequently, in studying ore bodies and mineral deposits, hydrocarbon accumulation and reservoir characterization,〔http://mmc2.igeofcu.unam.mx/cursos/gest/Articulos/Reservoir%20Caracterization/Multiple-point%20geostatistics%20a%20quantitative%20vehicle%20for%20integrating%20geologic%20analogs%20into%20multiple%20reservoir%20models.pdf〕 geoscientists always face heterogeneous and uncertain situation. Also in structural geology and many other earth-science fields, experts have to cope with heterogeneity in their investigations. *In medicine and genetics, a genetic or allelic heterogeneous condition is one where the same disease or condition can be caused, or contributed to, by several factors. In the case of genetics, varying different genes or alleles. *In cancer research, cancer cell heterogeneity is thought to be one of the underlying reasons that make treatment of cancer difficult. *In statistical meta-analysis, study heterogeneity is when multiple studies on an effect are actually measuring somewhat different effects due to differences in subject population, intervention, choice of analysis, experimental design, etc.; this can cause problems in attempts to summarize the meaning of the studies. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Homogeneity and heterogeneity」の詳細全文を読む スポンサード リンク
|