Population classification

Multicolour photometric systems that have been used for various sorts of stellar and stellar-population classification are listed with their spectral reponse curves in the website... 

The official estimate in 1998 also includes a breakdown by race (table 9.8) Note that Hispanic is a special ethnic designation, and can be of any race. America is becoming less white, as most racial minorities are experiencing population increases faster than the whites. There is also the rise of the multi-racial population in America, which will be included in future population classifications as a separate category. All these characteristics and changes in the population are important, as marketers need to study the consumption preferences of each segment of the population. 

In every part of the world, the same type of classification as above is found for fuels premium or regular, with or without lead. The octane numbers can be different from one country to another depending on the extent of development of their car populations and the capabilities of their local refining industries. The elimination of lead is becoming the rule wherever there are large automobile populations and severe anti-pollution requirements. Thus the United States, Japan and Canada no longer distribute leaded fuels. (... 

Knowledge of the underlying nuclear dynamics is essential for the classification and description of photochemical processes. For the study of complicated systems, molecular dynamics (MD) simulations are an essential tool, providing information on the channels open for decay or relaxation, the relative populations of these channels, and the timescales of system evolution. Simulations are particularly important in cases where the Bom-Oppenheimer (BO) approximation breaks down, and a system is able to evolve non-adiabatically, that is, in more than one electronic state. 

Brenner S E, C Chothia and T ] P Hubbard 1997. Population Statistics of Protein Structures Lessons from Structural Classifications. Current Opinion in Structural Biology 7 369-376. 

When constmction is complete, the pipeline must be tested for leaks and strength before being put into service industry code specifies the test procedures. Water is the test fluid of choice for natural gas pipelines, and hydrostatic testing is often carried out beyond the yield strength in order to reHeve secondary stresses added during constmction or to ensure that all defects are found. Industry code limits on the hoop stress control the test pressures, which are also limited by location classification based on population. Hoop stress is calculated from the formula, S = PD/2t, where S is the hoop stress in kPa (psig) P is the internal pressure in kPa (psig), and D and T are the outside pipe diameter and nominal wall thickness, respectively, in mm (in.). 

Median Lethal Dose (LD) The statistically derived single dose of a chemical that can be c.xpected to cause death in 50% of a given population of organisms under a defined set of experimental conditions. This figure has often been used to classify and compare toxicity among chemicals but its value for this purpose is doubtful. One commonly used classification of this kind is as follows ... 

Considering evidence from both field and mesocosm studies, it may be concluded that certain groups of aquatic macroinvertebrates are sensitive to pyrethroids and that there can be changes, in the short term, at the population level and above with exposure to environmentally realistic concentrations of them. It should be possible to pick up effects of this kind in natural waters using ecological profiling, for example, the River Invertebrate Prediction and Classification System (RIVPACS). There is... 

Sampling studies can be classified Into two types - enumeratlve, or descriptive, and analytic (j ). The classification Is Important because the applicable statistical methods and approaches are different for these two types. The objective of either type of study Is to provide a basis for action. In an enumeratlve study the action Is directed to the population from which the samples were taken. How or why the population was formed Is not of primary Interest. In an analytic study, the primary Interest Is the causal system or process which created the conditions observed In the study. Action taken Is directed toward this process rather than the population sampled. 

It should be noted that the decomposition shown in Eq. 3.7.2 is not necessarily a subdivision of separate sets of spins, as all spins in general are subject to both relaxation and diffusion. Rather, it is a classification of different components of the overall decay according to their time constant. In particular cases, the spectrum of amplitudes an represents the populations of a set of pore types, each encoded with a modulation determined by its internal gradient. However, in the case of stronger encoding, the initial magnetization distribution within a single pore type may contain multiple modes (j)n. In this case the interpretation could become more complex [49]. 

Kleinman (1986) claimed that neurasthenia was a cultural form of chronic somatization that outlined several different types of psychopathological disorders, the major depressive disorder included in western classifications being the one that best accounted for this disorder. This would explain the lower rate of prevalence of the diagnosis of depressive disorder among the Chinese population. 

In its continuing effort to improve the safety and efficacy of drugs in the pediatric population, the U.S. Food and Drug Administration (FDA) has defined five subgroups of this population based on age. Each subgroup is not homogeneous but does contain similar characteristics that are considered milestones in growth in development. The FDA classifications are listed in Table 1. 

Age classifications do not provide an ill-inclusive method for establishing pediatric doses. Based on current knowledge, the most accurate pediatric doses are determined utilizing both weight and age. Dosing based on surface area has been shown to have no practical advantages for the general pediatric population [1]. 

Chronological Age. Because of this wide variation within the elderly population, it is difficult to devise a catch-all age one must attain to be considered elderly. Within the government, there also appears to be a problem of consistently defining this age group. Table 2, which lists a variety of federally funded programs and their corresponding age criteria, illustrates this point quite well. Table 3 lists what seems to be one of the better classification systems that has been devised [5], As well as being the system currently used by the U.S. Bureau of the Census, it is often implemented in studies that specifically deal with elderly populations [6,7]. 

We can distinguish the algorithms in two kinds for the regressions and the classification. Regression methods get a continuous value. Classifiers find the category, for instance the toxicity class, of elements of a population. 

One important implication of the relationship between classification and theory is that classification systems define and propel research. Classification is a necessary starting point for the vast majority of research that takes place in mental health. Studies would not be funded or published if clinical populations were not first defined on the basis of diagnostic criteria. We are emphasizing that an inadequate classification scheme is likely to create a faulty Starting point that results in considerable expense in terms of time, effort, and research dollars (not to mention the human costs in regard to delaying our ultimate understanding of these disorders). 

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