Age structure

Information for the prosopographical study in this section has been drawn from IB, Miles (ed.), 1976, and successive editions of American Men of Science American Men and Women of Science. We have also used the Biographical Memoirs of the National Academy of Sciences and IB, Haynes (ed.), 1951. (For a similar study conducted in the early 1930s, see IB, Howe and Nelson, 1933.) Table 6.37 gives a list of American Chemical Society presidents. 

A 1955 survey of sixty-seven American scientific and learned societies showed that presidents of these organizations were most frequently between the ages of 52 and 62 at the time of first election (III, Lehman, 1955) see also III, Zuckerman, 1970, 239. For a general discussion of the implications of age stratification in science, see III, Zuckerman and Merton, 1972. 

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Conclusions satellite must be fairly large only one satellite contributes at the solar radius the age structure remains a problem (i.e. that very old thin disk stars are predicted and not observed, so far )... 

Hagstrum, D.W. and Gilbert, E.E. 1976. Emigration rate and age structure dynamics of Tribolium castaneum populations during growth phase of a colonization episode. Environ. Entomol. 5, 445-448. 

Harris, P.D., Jansen, P.A. and Bakke, T.A. (1994) The population age structure and reproductive biology of Cyrodactylus salaris Malmberg (Monogenea). Parasitology 1 08, 1 67-1 73. 

Table 10 shows seasonal variation in the age composition of Black Sea anchovy and sprat. The weight of an average fish in a population is evaluated from the age structure of the population and the share of the total biomass contributed by each age group. In horse-mackerel, pickerel and whiting, the proportion of the different age groups keeps stable all the year round, while in... 

In northern seas, fish such as herring, cod, haddock and flounder show intraspecies population differences in life span, structure, age at maturity and various physiological and biochemical characteristics (Shatunovsky, 1963, 1970 Love, 1970,1980 Storozhuk, 1971 Lapin, 1973). In contrast, fish from the Black, Azov and Mediterranean Seas have shorter life spans and display less distinct intraspecifc differences. Moreover, within one sea population, fish of one species do not differ much in age structure, fecundity or spawning character. The most pronounced difference in the latter group of species is the rate of lipid accumulation in sprat from different sites in the Black Sea and anchovy in the Azov Sea (Shulman, 1972b). Comparison of anchovy from the Azov, Black and Mediterranean Seas shows more marked differences in the levels of accumulated lipid and the growth rate (Chapter 2). 

K. Miyazaki, R. Nagai, and S. Horiuchi, Formation of pentosidine-like AGE structure from creatine, in G, 2002, 457-458. 

Drucker s example uses changes in population (i.e. size/young adults the third world) age structure especially more elderly people distribution between town and country more women in employment more in further/higher education higher disposable income. With little analysis consequences are predictable. For chemistry opportunity lies with medicines for the aged e.g. anti Alzheimer s disease, life style drugs and nutriceuticals. 

The first thing to note is that the age structure of this group in August 1970 was strikingly concentrated, with 70 percent between the ages of forty and fifty-five. Presumably, most had reached a stage of their careers where they enjoyed a measure of reputational authority and job security. All those who worked in academia had tenure, and all but one was full professor two were department chairs. All but two of those employed in government or private laboratories occupied administrative as well as research positions, for example, as laboratory director, branch chief, or division head. 

Brian Charlesworth Evolution in age-structured populations Stephen Childress Mechanics of swimming and flying C. Cannings and E. A. Thompson Genealogical and genetic structure Frank C. Hoppensteadt Mathematical methods of population biology... 

Chesley J. T., Rudnick R. L., and Lee C.-T. (1999) Re—Os systematics of mantle xenohths from the East African rift age, structure, and history of the Tanzanian craton. Geochim. Cosmochim. Acta 63, 1203—1217. 

Hurford A. J., Fitch F. J., and Clarke A. (1984) Resolution of the age structure of detrital zircon populations of two lower Cretaceous sandstones from the Weald of England by fission track dating. Geol. Mag. 121, 285-317. 

DuBois L. G. and PreU W. L. (1988) Effects of carbonate dissolution on the radiocarbon age structure of sediment mixed layers. Deep-Sea Res. 35, 1875-1885. 

A steady state natural population, characterized by a continuous generation/destruction (birth/ death) cycle, is usually typified by an age structure similar to that in Figure 1, the cumulative curve defining all necessary parameters of a given population. These are its half-life mean age hnean> d obUvion age or life expectancy... 

These relationships are valid for populations of constant size. For non-steady-state populations with stable age structures—i.e., those with overall rates of growth or decline much slower than the rates of recycling of their constituents—the age distributions approach the pattern of the constant-size populations. The calculated recycling rates are therefore identical. For populations where the overall growth (decline) approaches the rate of recycling of constituent units, independent criteria are required to differentiate recycling from the growth (decline) component. 

To the extent the current terrestrial sink is a result of regrowth (changes in age structure), the future terrestrial sink is more constrained. First, the net effect of continued land-use change is likely to release carbon, rather than store it. Second, forests that might have accumulated carbon in recent decades (whatever the cause) will cease to function as sinks if they are turned into croplands. Third, the current sink in regrowing forests will diminish as forests mature (Hurtt et al., 2002). 

Chesley, j. T., Rudnick, R. L. Lee, C. T. 1999. Re-Os systematics of mantle xenoliths from the East African Rift age, structure and history of the Tanzanian craton. Geochimica et Cosmochimica Acta, 63, 1203-1217. 

Further, the erosion law factor K, defined in equation (4), regulates the age distribution of eroded material relative to the age structure of the crust. Thus for a given crust mass v. time curve, the three parameters E, R and K fully describe the crust formation and erosion history. In the present modelling E was varied between 0.2 and 1, R from 0.3 to 0.7, and K from 1.5 to 3.5. The approach used and the effective partition coefficients, as well as initial (meteori-tic) concentrations of the trace species are the same as those used by Kramers Tolstikhin (1997) and Nagler Kramers (1998). 

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