965 research outputs found
The growth and structure of human populations: A mathematical investigation. By Ansley J. Coale. xvii + 227 pp., figures, glossary, index. Princeton University Press, Princetonn, New Jersey. 1972. $9.50 (cloth)
No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37544/1/1330400119_ftp.pd
On the systematic bias in skeletal sexing
Comparison of a large series of sexed adult skeletal populations and a similar series of adult pre-industrial peoples shows that there is a regular and systematic bias in the sexing of adult skeletons. This bias, which is about 12% in favor of males, is due to the nature of secondary sex characteristics in bone. It should be corrected in skeletal series before demographic analysis is made of them. Application of this knowledge and the same data to problems of age-specific male and female mortality rates is inconclusive, but points to an area for important future investigation. Application to the fossil record confirms some ecological ideas about human evolution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37528/1/1330370208_ftp.pd
A generalized model for competition between hominid populations
A simple mathematical model can represent competition between two hominid populations which includes elements of both trophic pre-emption and killing. The ultimate outcome of such competition can be determined if certain parameters are estimated. Various values of these parameters can represent various types of competition which occur between hominid groups. The model is used to argue that the two-species explanation of Australopithecine fossils is unrealistic and that a one-species view is more compatible with the facts. This model lends itself to first-order approximation of many situations of interest to anthropologists. The form of the equations for several situations is given, as is a solution for the ultimate equilibrium population densities of the two competing groups.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34043/1/0000320.pd
Temperate Fruit and Vegetable Trade under the GATT
The Uruguay Round of the General Agreement on Tariffs and Trade (GATT), if negotiated to a successful completion, will affect world trading patterns. This paper summarizes and analyzes the structure of the international markets for fruits and vegetables, and projects changes in response to reforms likely to follow a successful GATT negotiation. The research focused on the European Community (EC), selected European Free-Trade Association (EFTA) nations, Thailand, Indonesia, Malaysia, Brazil, Chile, and Colombia
Serotonin Mediated Cluster Headache, Trigeminal Neuralgia, Glossopharyngeal Neuralgia, and Superior Laryngeal Neuralgia with SAD Chronicity
Cluster headache is a rare and severe pain syndrome with elusive pathophysiology. Serotonin pathways within the brainstem may be implicated in cluster headache with seasonal affective disorder and a subset of cranial nerve neuralgias. We describe and chronicle a syndrome consisting of cluster headache, seasonal affective disorder, with associated trigeminal, glossopharyngeal, superior laryngeal neuralgias in an 11-year-old female. Pharmacologic interventions for this patient were examined in conjunction with current classification, location and function of serotonin receptors. Etiology is postulated as mixed cranial nerve excitation via endogenous 5-HT (agonist) activity of 5-HT 3 receptors within the nucleus tractus solitarius and trigeminal tract nucleus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43959/1/10578_2004_Article_303073.pd
The demographic stability of small human populations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21866/1/0000270.pd
Discrete demographic models with density-dependent vital rates
The standard Leslie model of population growth in an age structured population is modified so as to incorporate density-dependent feedback control on each parameter of the standard projection matrix. Under fairly general conditions, the population converges to a stable age-distribution and a constant population size. This steady-state solution is uniquely determined by the parameters of the model. In general, fertility damping results in a flatter age-distribution than yielded by the undamped Leslie model. General survival damping results in the Leslie age-distribution. Post-infant survival damping results in a very steep age-distribution. For populations with high intrinsic growth rates, these differences in stable age-distributions are pronounced. For populations of low intrinsic growth rate, the patterns are the same, but the differences in stable age-distribution are more subtle. The age-distribution usually converges rapidly to the steady-state array, although population size generally takes longer to approach a stable value. Convergence properties are described for a series of cases which show periodicity. Such cases arise from “periodic” behavior of certain fertility-damping strategies, and ultimately approach a stable steady-state, although convergence may be very slow. Although the model is very general, it can be considerably simplified in practice. Special cases, which can be constructed, are the Malthusian (Leslie) model and the Logistic model. As a generality, the model is approximately Logistic, once the age-distribution approaches the steady-state array. One may use this fact for purposes of population projection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47713/1/442_2004_Article_BF00553449.pd
Additive genetic variation in the craniofacial skeleton of baboons (genus Papio) and its relationship to body and cranial size
Objectives Determining the genetic architecture of quantitative traits and genetic correlations among them is important for understanding morphological evolution patterns. We address two questions regarding papionin evolution: (1) what effect do body and cranial size, age, and sex have on phenotypic (VP) and additive genetic (VA) variation in baboon crania, and (2) how might additive genetic correlations between craniofacial traits and body mass affect morphological evolution? Materials and Methods We use a large captive pedigreed baboon sample to estimate quantitative genetic parameters for craniofacial dimensions (EIDs). Our models include nested combinations of the covariates listed above. We also simulate the correlated response of a given EID to selection on body mass alone. Results Covariates account for 1.2%–91% of craniofacial VP. EID VA decreases across models as more covariates were included. The median genetic correlation estimate between each EID and body mass is 0.33. Analysis of the multivariate response to selection reveals that observed patterns of craniofacial variation in extant baboons cannot be attributed solely to correlated response to selection on body mass, particularly in males. Discussion Because a relatively large proportion of EID VA is shared with body mass variation, different methods of correcting for allometry by statistically controlling for size can alter residual VP patterns. This may conflate direct selection effects on craniofacial variation with those resulting from a correlated response to body mass selection. This shared genetic variation may partially explain how selection for increased body mass in two different papionin lineages produced remarkably similar craniofacial phenotypes
Cool bottom processes on the thermally-pulsing AGB and the isotopic composition of circumstellar dust grains
(Abridged) We examine the effects of cool bottom processing (CBP) on several
isotopic ratios in the convective envelope during the TP-AGB phase of evolution
in a 1.5 M_sun initial-mass star of solar initial composition. We use a
parametric model which treats extra mixing by introducing mass flow between the
convective envelope and the underlying radiative zone. The parameters of this
model are the mass circulation rate (Mdot) and the maximum temperature (T_P)
experienced by the circulating material. The effects of nuclear reactions in
the flowing matter were calculated using a set of structures of the radiative
zone selected from a complete stellar evolution calculation. The compositions
of the flowing material were obtained and the resulting changes in the envelope
determined. Abundant ^26Al was produced by CBP for log T_P > 7.65. While
^26Al/^27Al depends on T_P, the isotopic ratios in CNO elements depend
dominantly on the circulation rate. The correspondence is shown between models
of CBP as parameterized by a diffusion formalism within the stellar evolution
model and those using the mass-flow formalism employed here. The isotopic
ratios are compared with the data on circumstellar dust grains. It is found
that the ratios ^{18}O/^{16}O, ^{17}O/^{16}O, and ^26Al/^27Al observed for
oxide grains formed at C/O < 1 are reasonably well-understood. However, the
^15N/^14N, ^12C/^13C, and ^26Al/^27Al in carbide grains (C/O > 1) require many
stellar sources with ^14N/^15N at least a factor of 4 below solar. The rare
grains with ^12C/^13C < 10 cannot be produced by any red-giant or AGB source.Comment: 35 pages, plus 18 included figures. Scheduled for January 10, 2003
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