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At least 199 records · Page 11Linked to original sources
PubMed1987

Past and recent attempts to model mortality at all ages.

"Most laws of mortality are partial in the sense that they apply only to a broad age group and not to all ages. This paper focuses on three laws of mortality that apply to all ages. Two of them were developed by the actuaries Thiele and Wittstein in the late 19th century. The third, developed by Heligman and Pollard, is of recent origin. The three laws are discussed with references to Scandinavian mortality data. The results suggest that the most recently proposed law can be used for generation of model life tables, for making population projections, simulations, and other statistical work where there is a need for a realistic model of human mortality."

Age Factors↗
PubMed1990

High fertility of Old Colony Mennonites in Mexico.

Old Colony Mennonites in Mexico appear to demonstrate natural fertility, using no form of artificial birth control and apparently not attempting to limit family size. The resulting fertility is nearly as high as that of the Hutterites, although the Mennonites lack the communal economic system of the latter. Most Mennonites in Mexico migrated from Canada in the 1920s, and the largest single settlement, called the Manitoba Colony, is one of four in the state of Chihuahua. A 1967 partial census obtained data from 38% of the Mennonite households. Family size in the sample was close to that in a local survey taken in the same year. Available church records matched with census forms permitted verification of and corrections to 560 female reproductive histories. The median number of live births to women over age 45 years was 9.5, compared with 10.4 in the Hutterites. Age-specific marital fertility rates and birth intervals closely resembled those of the Hutterites.

Adolescent↗
PubMed1986

The epidemiology of infant deaths in the Armenian parish records of Lebanon.

It is difficult to study time trends in mortality from most developing countries due to the lack of an appropriate data base. The present investigation is based on data from parish records of the Armenian Apostolic churches in Lebanon. Death and baptismal registers have been regularly maintained in these churches from 1863. Infant deaths were identified in the registers of the 13 churches. Available data on these deaths were abstracted, coded and analysed. Denominators for the different periods of study and for the various churches were calculated from baptismal records. The study shows that there has been a constant drop in the infant deaths over the review period. Infant mortality rates were higher in the parishes located in refugee camp areas. The most important recorded causes of death included diarrhoea and pneumonia. A study of clustering of deaths by time and place revealed a major epidemic of measles with high fatality in 1926. This epidemic had been previously unrecorded. The present study demonstrates the use of non-traditional data sources to assess long-term secular trends of mortality.

Armenia↗
PubMed2003

Joint Bayesian estimation of mutation location and age using linkage disequilibrium.

Associations between disease and marker alleles on chromosomes in populations can arise as a consequence of historical forces such as mutation, selection and genetic drift, and is referred to as "linkage disequilibrium" (LD). LD can be used to estimate the map position of a disease mutation relative to a set of linked markers, as well as to estimate other parameters of interest, such as mutation age. Parametric methods for estimating the location of a disease mutation using marker linkage disequilibrium in a sample of normal and affected individuals require a detailed knowledge of population demography, and in particular require users to specify the postulated age of a mutation and past population growth rates. A new Bayesian method is presented for jointly estimating the position of a disease mutation and its age. The method is illustrated using haplotype data for the cystic fibrosis deltaF508 mutation in Europe and the DTD mutation in Finland. It is shown that, for these datasets, the posterior probability distribution of disease mutation location is insensitive to the population growth rate when the model is averaged over possible mutation ages using a prior probability distribution for the mutation age based on the population frequency of the disease mutation. Fewer assumptions are therefore needed for parametric LD mapping.

Bayes Theorem↗
PubMed1991

Applications of the Heligman/Pollard model mortality schedule.

"The United Nations working manual for MORTPAK-Lite, a software package for demographic measurement, includes among its 16 computer programs a routine (UNABR) that graduates a set of age-specific probabilities of dying...for the standard set of five-year age groups into a set of single-year probabilities of dying. The graduation is effected with an eight-parameter 'law of mortality' known as the Heligman/Pollard model mortality schedule. Model mortality schedules...are useful in mortality analysis and forecasting. Several such applications are illustrated in this article: a historical time-series analysis, a forecasting application, studies of causes of death, spatial differences and sex-specific mortality disaggregated by race." The geographical focus is on the United States, England, and Australia.

Age Factors↗
PubMed1997

Medical methods for termination of pregnancy. Report of a WHO Scientific Group.

Recent estimates indicate that as many as 53 million pregnancies are terminated by induced abortion each year. One-third of these abortions are performed in unsafe conditions, resulting in some 50,000-100,000 deaths each year, and many more women have complications which may have long-term consequences for their health. This report of a WHO Scientific Group reviews medical methods for the termination of first- and second-trimester pregnancy, including studies on the agents that induce abortion, their mode of action, and their efficacy compared with surgical methods. It examines the factors that cause women to seek abortion services, as well as those that affect complications, their prevention and the acceptability of different methods. The report makes a number of recommendations on the service environment required to employ medical methods and for further research in the field of medical termination of pregnancy.

Abortifacient Agents↗
PubMed2004

Evolutionary history of the northern leopard frog: reconstruction of phylogeny, phylogeography, and historical changes in population demography from mitochondrial DNA.

This study uses a combined methodological approach including phylogenetic, phylogeographic, and demographic analyses to understand the evolutionary history of the northern leopard frog, Rana pipiens. We tested hypotheses concerning how (or if) known geological events and key features of the species biology influenced the contemporary geographic and genetic distribution of R. pipiens. We assayed mitochondrial DNA variation from 389 individuals within 35 populations located throughout the species range. Our a priori expectations for patterns and processes influencing the current genetic structure of R. pipiens were supported by the data. However, our analyses revealed specific aspects of R. pipiens evolutionary history that were unexpected. The phylogenetic analysis indicated that R. pipiens is split into populations containing discrete eastern or western haplotypes, with the Mississippi River and Great Lakes region dividing the geographic ranges. Nested clade analysis indicated that the biological process most often invoked to explain the pattern of haplotype position is restricted gene flow with isolation by distance. Demographic analyses showed evidence of both historical bottlenecks and population expansions. Surprisingly, the genetic evidence indicated that the western haplotypes had significantly reduced levels of genetic diversity relative to the eastern haplotypes and that major range expansions occurred in both regions well before the most recent glacial retreat. This study provides a detailed history of how a widespread terrestrial vertebrate responded to episodic Pleistocene glacial events in North America. Moreover, this study illustrates how complementary methods of data analysis can be used to disentangle recent and ancient effects on the genetic structure of a species.

Animals↗
PubMed2004

Genetic analysis of complex demographic scenarios: spatially expanding populations of the cane toad, Bufo marinus.

Inferring the spatial expansion dynamics of invading species from molecular data is notoriously difficult due to the complexity of the processes involved. For these demographic scenarios, genetic data obtained from highly variable markers may be profitably combined with specific sampling schemes and information from other sources using a Bayesian approach. The geographic range of the introduced toad Bufo marinus is still expanding in eastern and northern Australia, in each case from isolates established around 1960. A large amount of demographic and historical information is available on both expansion areas. In each area, samples were collected along a transect representing populations of different ages and genotyped at 10 microsatellite loci. Five demographic models of expansion, differing in the dispersal pattern for migrants and founders and in the number of founders, were considered. Because the demographic history is complex, we used an approximate Bayesian method, based on a rejection-regression algorithm, to formally test the relative likelihoods of the five models of expansion and to infer demographic parameters. A stepwise migration-foundation model with founder events was statistically better supported than other four models in both expansion areas. Posterior distributions supported different dynamics of expansion in the studied areas. Populations in the eastern expansion area have a lower stable effective population size and have been founded by a smaller number of individuals than those in the northern expansion area. Once demographically stabilized, populations exchange a substantial number of effective migrants per generation in both expansion areas, and such exchanges are larger in northern than in eastern Australia. The effective number of migrants appears to be considerably lower than that of founders in both expansion areas. We found our inferences to be relatively robust to various assumptions on marker, demographic, and historical features. The method presented here is the only robust, model-based method available so far, which allows inferring complex population dynamics over a short time scale. It also provides the basis for investigating the interplay between population dynamics, drift, and selection in invasive species.

Animals↗
PubMed1981

A procedure for investigating cancer cluster reports.

Cancer clusters are described as epidemiologic leads to environmental determinants of cancer. A historical perspective of cancer cluster reports is offered with comments on the various investigative methods. A specific, systematic protocol for responding to cancer cluster reports is offered with a detailed example. Suggestions for decision making and comments on statistical analysis are also offered. Emphasis is placed on the participant interview and on the use of non-case data.

Demography↗
PubMed2001

Using linked markers to infer the age of a mutation.

Advances in sequencing and genotyping technologies over the last decade have enabled geneticists to easily characterize genetic variation at the nucleotide level. Hundreds of genes harboring mutations associated with genetic disease have now been identified by positional cloning. Using variation at closely linked genetic markers, it is possible to predict the times in the past at which particular mutations arose. Such studies suggest that many of the rare mutations underlying human genetic disorders are relatively young. Studies of variation at genetic markers linked to particular mutations can provide insights into human geographic history, and historical patterns of natural selection and disease, that are not available from other sources. We review two approaches for estimating allele age using variation at linked genetic markers. A phylogenetic approach aims to reconstruct the gene tree underlying a sample of chromosomes carrying a particular mutation, obtaining a "direct" estimate of allele age from the age of the root of this tree. A population genetic approach relies on models of demography, mutation, and/or recombination to estimate allele age without explicitly reconstructing the gene tree. Phylogenetic methods are best suited for studies of ancient mutations, while population genetic methods are better suited for studies of recent mutations. Methods that rely on recombination to infer the ages of alleles can be fine-tuned by choosing linked markers at optimal map distances to maximize the information available about allele age. A limitation of methods that rely on recombination is the frequent lack of a fine-scale linkage map. Maximum likelihood and Bayesian methods for estimating allele age that rely on intensive numerical computation are described, as well as "composite" likelihood and moment-based methods that lead to simple estimators. The former provide more accurate estimates (particularly for large samples of chromosomes) and should be employed if computationally practical.

Alleles↗
PubMed1984

Cohort marriage and divorce in five Western countries.

An analysis of cohort trends in family formation and dissolution in five Western countries during the twentieth century is presented. The countries concerned are the United States, England and Wales, Belgium, Sweden, and Switzerland. "To obtain the indicators of family formation and dissolution used in this study, male and female cohort marital status life tables were constructed in each of the five countries for single year cohorts born between the years 1888 and 1945." Consideration is also given to the impact of changes in mortality. Data are from official sources. This is a revised version of a paper originally presented at the 1983 Annual Meeting of the Population Association of America (see Population Index, Vol. 49, No. 3, Fall 1983, pp. 384-5).

Americas↗
PubMedDate not supplied

Interrelationships between mortality and fertility in Germany: rural and urban Prussia and modern Germany.

"The paper investigates the interrelationship between fertility and infant mortality and its economic determinants by time-series methods for historical and modern Germany. It is studied whether the causal effects of infant mortality on fertility have to be considered as hoarding or replacement, and whether the costs of nutrition have an influence on family decision making about demographic variables. Results show that there are indications for replacement motives, and that economic factors matter." (SUMMARY IN FRE AND ITA)

Demography↗
PubMed1995

[Diffusion of fertility control practices: moments, mechanisms, and determinants].

"In Brazil and in Bahia, distinct fertility control practices, performed through the so-called traditional techniques, have been socially diffused among the traditional elites and the more highly educated groups of the middle class since the end of the 19th century. These practices have produced a slow but systematic tendency to inter-generational decline in completed parity.... These facts support the hypothesis that the ethical changes involved in the acceptance and legitimacy of those practices were themselves a consequence of their increased prevalence and the consolidation of norms regarding the patterns of fertility control in these social classes.... Once anti-natality has been consolidated as a theoretical and practical reference system for the behaviour of the higher classes, the institutional apparatus of the society turned on the popular classes with lower levels of education and medical care, and diffused fertility control in these groups." (SUMMARY IN ENG)

Americas↗