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PubMed2004

Influence of spatial and temporal heterogeneities on the estimation of demographic parameters in a continuous population using individual microsatellite data.

Drift and migration disequilibrium are very common in animal and plant populations. Yet their impact on methods of estimation of demographic parameters was rarely evaluated especially in complex realistic population models. The effect of such disequilibria on the estimation of demographic parameters depends on the population model, the statistics, and the genetic markers used. Here we considered the estimation of the product Dsigma2 from individual microsatellite data, where D is the density of adults and sigma2 the average squared axial parent-offspring distance in a continuous population evolving under isolation by distance. A coalescence-based simulation algorithm was used to study the effect on Dsigma2 estimation of temporal and spatial fluctuations of demographic parameters. Estimation of present-time Dsigma2 values was found to be robust to temporal changes in dispersal, to density reduction, and to spatial expansions with constant density, even for relatively recent changes (i.e., a few tens of generations ago). By contrast, density increase in the recent past gave Dsigma2 estimations biased largely toward past demographic parameters values. The method was also robust to spatial heterogeneity in density and estimated local demographic parameters when the density is homogenous around the sampling area (e.g., on a surface that equals four times the sampling area). Hence, in the limit of the situations studied in this article, and with the exception of the case of density increase, temporal and spatial fluctuations of demographic parameters appear to have a limited influence on the estimation of local and present-time demographic parameters with the method studied.

Algorithms↗

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↗

PubMed2004

[Cancer and demographic transition].

Two phenomena, one of which relates to the area of human reproduction and the other to the frequency, distribution, and control of disease in a population have emerged in the previous century and continue intensively to develop nowadays. Both these phenomena are directly related to the changes which are occurring in the incidence and prevalence of malignant tumours, as well as to mortality from them and to the opportunities for cancer control. The first of these phenomena has been denominated as the demographic, and the second as the epidemiological transition. The commonly accepted definition of the demographic transition is currently applied to designate a sustainable change in the type of population reproduction, when an initial and abrupt acceleration of population growth is replaced by its rapid deceleration with a subsequent stabilization of a population and a sharp change in its age structure. Demographic transition develops in a brief historical space of time and has the character of a global process. Population ageing and disequilibrium between the younger and older generations are the most important consequences of the demographic transition, and must inevitably influence the strategy and implementation of national cancer control programs. As life expectancy increases, so does the certainty that people will become more and more prone to diseases that are more common among older age groups, i.e. noncommunicable diseases and cancer in particular, rather than being affected by epidemics of infectious diseases. This situation is known as the epidemiological transition and reflects spectacular shifts in the pattern and causes of death and morbidity that have taken place in the vast majority of countries over the previous century. Epidemiological transition results in accession by poor countries to the problems of the rich, and leads to the "double burden" of disease in countries whose economies are undergoing transition, because of the still continuing burden of endemic infectious diseases. Russia is entering the final stages both of the demographic and the epidemiological transition, a period when numerous reasons, increasing demands on the systems of social protection and public health are inevitable. During the years 1992 to 2001, cancer incidence increased from 271.8 up to 313.9 per 100,000 population, i.e. a growth of over 16% and an annual rate of growth of 1.7%. According to the global estimates provided by the International Agency for Research on Cancer the number of new cancer cases in the year 2000 exceeded 10 million, and the number of deaths from cancer reached 6.2 million. The annual growth rate of global cancer incidence during the last 25-30 years was higher than the global population growth rate. Analysis of data available from population based cancer registries in Russia and abroad confirms the conclusion that cancer is mainly the fate of people belonging to the older age groups. Given the levels of exposure to specific carcinogens and genetic predisposition factors, the incidence of cancer should be considered as an exponential function of age. The unfeasibility of attempts to change, in the foreseeable future, the rate and trend of demographic transition and demographic ageing, in particular, is obvious. It would therefore be more feasible to envisage their probable consequences and to adapt the limited resources of national health and social support services to the needs of cancer control, which will significantly increase in the near future.

Age Distribution↗

PubMed1996

Demographic response to rural restructuring and counterurbanisation in South Australia, 1981-1991.

"Using South Australia as a case study, this paper seeks to trace and demonstrate two processes (counterurbanisation and rural restructuring) whose effects overlap to differentiate and characterise the population geography of...two zones, separated by a transition along the outer fringe of Adelaide's urban field.... In the demographic core zone [rural restructuring] has been partly offset by continued counterurbanisation, resulting in demographic mixing and rural dilution. The 1981-91 population growth in rural communities is shown to be more a function of population density at the outset of the period than of initial population size. Demographic growth...is shown to conform to a simple unidimensional scale, allowing the production of a clear, easily interpretable typology of rural demographic change with few non-conforming statistical areas. At a local level within individual rural communities, demographic decline is shown to be accompanied by increased concentration of the population into small towns, while demographic growth is associated with deconcentration."

Australia↗

PubMed1992

Multiregional demographic projections in practice: a metropolitan example.

"This paper examines options for local and regional projections which reflect both demographic interdependencies with jobs and housing at this area scale, and the inapplicability of traditional demographic projection methods to population or areal subdivisions. This context for local demographic projections requires constraints (for example, to job and housing forecasts or to higher area totals), the use of proxy or explanatory indicators to predict demographic rates or totals, and parameterization of demographic schedules, to facilitate comparison across numerous localities and to set future assumptions about demographic components. The traditional framework of self-contained projection by deterministic cohort survival is therefore widened to include regio-scientific and stochastic modelling concepts. The framework for empirical analysis is London [England] and its boroughs." (SUMMARY IN FRE AND GER)

Demography↗

PubMed2005

Relationships between demographic variables and quality of life in a population of Dutch adult psychiatric outpatients.

BACKGROUND: Examinations of the role of demographic characteristics in quality of life (QOL) in psychiatric samples are not new. However, serious limitations of previous research have been that (1) QOL was not assessed according to current recommendations, (2) assessment of QOL was often hampered by a substantial overlap in content between symptoms and QOL measures, and (3) the majority of the study samples had quite specific characteristics hampering the generalizability of results, as a result of which clinical implications of the results remained unclear. The aim of the present study was to investigate explicitly the relationships between demographics and QOL in a sample reflecting the general population of psychiatric outpatients, QOL being assessed in a comprehensive, culturally sensitive, and subjective way, paying attention to the relative importance of its various facets. The main hypothesis was that these relationships would be rather weak. METHOD: From a population of 533 adult Dutch psychiatric outpatients, 495 participants completed the World Health Organization Quality of Life (WHOQOL)-Bref for assessing QOL. Furthermore, several demographic characteristics were recorded. RESULTS: Statistically significant correlations were found between partner relationship, habitual status, work, and sick leave and the WHOQOL-Bref domains social relationships and environment. Psychological health was associated to partner relationship, educational level, and sick leave. The total amount of QOL variance explained by demographics was rather low. CONCLUSION: Amongst factors determining QOL, demographic characteristics are relatively unimportant. Therefore, paying attention to demographics during psychiatric treatment will probably have little effect on improvement of QOL.

Adult↗

PubMed1998

Relationships between isoinertial lumbar dynamometry parameters and demographic parameters in chronic low back pain patients.

The purpose of this study was to investigate which demographic parameters are most important in relation to lumbar dynamometry performance in patients with chronic low back pain (LBP). Forty-five chronic LBP patients participated in this study. Gender, age, weight and height were determined and a lumbar dynamometry measurement was carried out, using the Isostation B200. Student's t-test, ANOVA techniques and correlation coefficients were used to investigate the relationships between each demographic parameter and lumbar dynamometry performance. Stepwise multiple linear regression analyses were performed afterwards to determine which demographic parameters are most important in relation to lumbar dynamometry performance. Results indicate significant relationships (1) between gender, height, weight and all lumbar dynamometry parameters and (2) between age and three of the six isometric torque parameters. No significant relationship was found between age and maximum velocity parameters. Results of the stepwise multiple linear regression analyses show that the demographic parameters explain 27-47% of the variance in maximum isometric strength parameters and 19-25% of the variance in maximum velocity parameters. Gender is the most important demographic parameter, being related to nearly all maximum isometric torque parameters (percentage explained variance 6-37%) and height is the only important demographic parameter related to the velocity parameters (percentage explained variance 19-25%). Weight and age account for only a small amount of variance in lumbar dynamometry parameters (percentage explained variance 5-7%), meaning that these parameters are non-relevant predictors.

Adult↗

PubMed2006

Demographic management in a federated healthcare environment.

OBJECTIVE: The purpose of this paper is to provide a further step toward the decentralization of identification and demographic information about persons by solving issues related to the integration of demographic agents in a federated healthcare environment. The aim is to identify a particular person in every system of a federation and to obtain a unified view of his/her demographic information stored in different locations. METHOD: This work is based on semantic models and techniques, and pursues the reconciliation of several current standardization works including ITU-T's Open Distributed Processing, CEN's prEN 12967, OpenEHR's dual and reference models, CEN's General Purpose Information Components and CORBAmed's PID service. RESULTS: We propose a new paradigm for the management of person identification and demographic data, based on the development of an open architecture of specialized distributed components together with the incorporation of techniques for the efficient management of domain ontologies, in order to have a federated demographic service. This new service enhances previous correlation solutions sharing ideas with different standards and domains like semantic techniques and database systems. The federation philosophy enforces us to devise solutions to the semantic, functional and instance incompatibilities in our approach. CONCLUSION: Although this work is based on several models and standards, we have improved them by combining their contributions and developing a federated architecture that does not require the centralization of demographic information. The solution is thus a good approach to face integration problems and the applied methodology can be easily extended to other tasks involved in the healthcare organization.

Computer Communication Networks↗

PubMed2005

Extinction in relation to demographic and environmental stochasticity in age-structured models.

The demographic variance of an age-structured population is defined. This parameter is further split into components generated by demographic stochasticity in each vital rate. The applicability of these parameters are investigated by checking how an age-structured population process can be approximated by a diffusion with only three parameters. These are the deterministic growth rate computed from the expected projection matrix and the environmental and demographic variances. We also consider age-structured populations where the fecundity at any stage is either zero or one, and there is neither environmental stochasticity nor dependence between individual fecundity and survival. In this case the demographic variance is uniquely determined by the vital rates defining the projection matrix. The demographic variance for a long-lived bird species, the wandering albatross in the southwestern part of the Indian Ocean, is estimated. We also compute estimates of the age-specific contributions to the total demographic variance from survival, fecundity and the covariance between survival and fecundity.

Age Factors↗

PubMed2000

Socio-demographic variables and 6 year change in body mass index: longitudinal results from the GLOBE study.

BACKGROUND: Body mass index (BMI) differs by socio-demographic variables, but the origin of these associations remains relatively unknown. OBJECTIVE: To investigate the association between socio-demographic variables and the subsequent change in BMI over six years. DESIGN: A Dutch prospective cohort study (GLOBE) from which data were used from initially 20-49-year-old subjects (males: n=362; females: n=405). BMI was calculated from self-reported body height and weight data obtained in 1991 and 1997. Socio-demographic variables used were sex, age, educational level and the occupational level of the main breadwinner, family income, marital status, religious affiliation and degree of urbanization and measured in 1991. RESULTS: Cross-sectionally, BMI was higher in males than in females. BMI was positively associated with age and negatively associated with educational level in both sexes, after adjustment for the other socio-demographic variables. A positive association of BMI with family income was found in males and a negative association with occupational level was found in females. During follow-up, BMI increased significantly more in females (from 23.0 (s.d. 3.3) to 24. 2 (s.d. 3.8)) than in males (from 24.3 (s.d. 2.9) to 25.1 (s.d. 3. 5)). With the exception of a significant lesser increase in BMI in initially 30-39-year-old women compared to initially 40-49-year-old women, no other statistically significant associations were found between socio-demographic variables and the 6-year change in BMI. CONCLUSIONS: Cross-sectional differences in BMI by socio-demographic variables are not due to different 6-year changes in BMI for categories of these variables in adulthood. Cross-sectional differences in BMI by educational level are probably established at the end of adolescence.

Adult↗

PubMed2025

Sex-biased Migration and Demographic History of the Big European Firefly Lampyris noctiluca.

Differential dispersion between the sexes can impact the colonization process and demographic history of a species. Here, we explored the demographic history of the big European firefly, Lampyris noctiluca, which exhibits female neoteny. Distribution of L. noctiluca extends throughout Europe, but nothing is known about its colonization process. To investigate its demographic history, we produced the first Lampyris genome (653 Mb), including an IsoSeq annotation and the identification of the X chromosome. We collected 115 individuals from six populations of L. noctiluca (Finland to Italy) and generated whole-genome re-sequencing data for each individual. We inferred several population expansions and bottlenecks throughout the Pleistocene that correlate with glaciation events. Surprisingly, we uncovered strong population structure and low gene flow. We reject a stepwise, south to north, colonization history scenario and instead uncovered a complex demographic history with a putative eastern European origin. Analyzing the evolutionary history of the mitochondrial genome as well as X-linked and autosomal loci, we found evidence of a maternal colonialization of Germany, putatively from a farther western European population, followed by a male-only migration from south of the Alps (Italy). Overall, investigating the demographic history and colonization patterns of a species should form part of an integrative approach of biodiversity research. Our results provide evidence of sex-biased migration which is important to consider for demographic, biogeographic and species delimitation studies.

Animals↗

PubMed2002

Demographic, mechanistic and density-dependent determinants of population growth rate: a case study in an avian predator.

Identifying the determinants of population growth rate is a central topic in population ecology. Three approaches (demographic, mechanistic and density-dependent) used historically to describe the determinants of population growth rate are here compared and combined for an avian predator, the barn owl (Tyto alba). The owl population remained approximately stable (r approximately 0) throughout the period from 1979 to 1991. There was no evidence of density dependence as assessed by goodness of fit to logistic population growth. The finite (lambda) and instantaneous (r) population growth rates were significantly positively related to food (field vole) availability. The demographic rates, annual adult mortality, juvenile mortality and annual fecundity were reported to be correlated with vole abundance. The best fit (R(2) = 0.82) numerical response of the owl population described a positive effect of food (field voles) and a negative additive effect of owl abundance on r. The numerical response of the barn owl population to food availability was estimated from both census and demographic data, with very similar results. Our analysis shows how the demographic and mechanistic determinants of population growth rate are linked; food availability determines demographic rates, and demographic rates determine population growth rate. The effects of food availability on population growth rate are modified by predator abundance.

Animals↗

PubMed1999

Oral health of children in South Australia by socio-demographic characteristics and choice of provider.

UNLABELLED: Australia has a highly developed school dental program for providing dental care to schoolchildren which operates alongside well-established private practice delivery of dental care. While free school-based dental care has high utilisation where offered, little is known about the oral health outcomes of groups of children across different providers of dental care, or patterns of service use. This paper investigates the effects of socio-demographic characteristics and choice of dental provider on oral health amongst a random sample of secondary school students residing in Adelaide, South Australia. OBJECTIVES: To describe the oral health of children by different dental provider groups, to describe the association of socio-demographic characteristics with oral health outcomes; and to describe the differences in oral health that remained after controlling for socio-demographic confounding, by dental provider group. METHODS: The study included metropolitan Adelaide schoolchildren from Year 9 and 10 school grades (n = 373). RESULTS: Children who received care from the School Dental Service (SDS) and from both the SDS and private dentists (Mixed) had significantly lower caries experience (DMFS) than children who received care from private dentists (Private) or who had not received any care for at least 2 years (No Recent Care). There were differences in the socio-demographic characteristics between children who used different dental providers, and these socio-demographic characteristics were significantly associated with levels of decayed, missing and filled surfaces and surfaces which had been fissure sealed. After controlling for socio-demographic characteristics using multiple regression, significant differences were seen in mean caries experience (DMFS) and mean numbers of decayed surfaces and filled surfaces. CONCLUSION: Although from less advantaged backgrounds, children seen through the SDS had more favourable oral health outcomes than children seen by a private dentist.

Adolescent↗

PubMed2004

Using insurance claims and demographic data for surveillance of children's oral health.

OBJECTIVES: This paper examines the utility of using private insurance and Medicaid dental claims as well as demographic data for assessing the oral health of children aged 5-12 years in Genesee County, Michigan, communities. METHODS: Dental insurance claims data from Delta Plan of Michigan and Michigan Medicaid, plus demographic data from the 1990 US Census (percent poverty) and from the 1995 National Center for Educational Statistics (percent free or reduced lunch eligibility), were compared to findings from two school-based oral health surveys. These surveys were the 1995 Genesee County Oral Health Survey and the 1998-2001 Mott Children's Health Center oral health screenings. Data were analyzed using zip codes, representing communities, as the comparison unit. Statistical comparisons using correlation coefficients were used to compare the findings from the six data sets. RESULTS: Using the insurance claims and school-based data, some communities consistently demonstrated high levels of dental caries or treatment for the primary dentition. The demographic measures were significantly associated with many of the primary dentition survey measures. The demographic data were more useful in identifying communities with high levels of dental disease, particularly in the primary teeth, than the insurance claims data. CONCLUSIONS: When screening is not practical, readily available demographic data may provide valuable oral health surveillance information for identification of high-risk communities, but these data do not identify high-risk individuals. In these analyses, demographic data were more useful than dental insurance claims data for oral health surveillance purposes.

Child↗

PubMed2006

Extrapolaholics anonymous: why demographers' rejections of a huge rise in cohort life expectancy in this century are overconfident.

Criticisms of demographers by other demographers have become frequent in scientific literature, generally consisting of accusations that trends observed in the recent past have been extrapolated unjustifiably into the future. Demographers, along with their colleagues in the actuarial profession, are in an invidious position in this regard, knowing full well that extrapolation is almost always only minimally justifiable, but knowing also that their readers, colleagues, and sources of funding tend to be much more interested in the future than in the past. It is unfortunate that, while actuaries typically resolve this dilemma by emphasizing the limitations of their methods and thereby lowering expectations that their predictions will be accurately fulfilled, demographers are more prone to respond combatively, attempting to reinforce the credibility of their extrapolations by recourse to data from areas in which their expertise is less tested, such as biology. This is valuable in that it raises the profile of the debate on the likely rate of scientific progress relevant to mortality rates, but it also runs the risk of lowering the technical quality of that debate, by telling policy makers and the public what they want to hear and thereby entrenching their expectations without recourse to the relevant biological facts. Extrapolations based on plausible sequences of scientific advances and the sociopolitical responses to them, summarized in this article, have led to the prediction of four-digit life expectancies of cohorts born in the 21st century and possibly even in the 20th. This prediction has attracted inevitable ridicule from prominent demographers, but being founded on science and sociology rather than on history it may be much more reliable than the extrapolations that those demographers presently prefer.

Cohort Studies↗

PubMed2002

The association between biomarker-based exposure estimates for phthalates and demographic factors in a human reference population.

Population-based estimates of environmental exposures using biomarkers can be difficult to obtain for a variety of reasons, including problems with limits of detection, undersampling of key strata, time between exposure and sampling, variation across individuals, variation within individuals, and the ability to find and interpret a given biomarker. In this article, we apply statistical likelihoods, weighted sampling, and regression methods for censored data to the analysis of biomarker data. Urinary metabolites for seven phthalates, reported by Blount et al., are analyzed using these methods. In the case of the phthalates data, we assumed the underlying model to be a log-normal distribution with the mean of the distribution defined as a function of a number of demographic variables that might affect phthalate levels in individuals. Included as demographic variables were age, sex, ethnicity, residency, family income, and education level. We conducted two analyses: an unweighted analysis where phthalate distributions were estimated with changes in the means of these distributions as a function of demographic variables, and a weighted prediction for the general population in which weights were assigned for a subset of the population depending on the frequency of their demographic variables in the general U.S. population. We used statistical tests to determine whether any of the demographic variables affected mean phthalate levels. Individuals with only a high school education had higher levels of di-n-butyl phthalate than individuals with education beyond high school. Subjects who had family income less than $1,500 in the month before sampling and/or only high school education had higher levels of n-butyl benzyl phthalate levels than other groupings. Di(2-ethylhexyl) phthalate was higher in males and/or in urban populations and/or in people who had family income less than $1,500 per month. Our findings suggest that there may be significant demographic variations in exposure and/or metabolism of phthalates and that health-risk assessments for phthalate exposure in humans should consider different potential risk groups.

Adult↗

PubMedDate not supplied

[Demographic-epidemiologic transition in Chile, 1960-2001].

BACKGROUND: In Chile, the demographic structure and the causes of morbidity and of mortality among the population have undergone major changes within a relatively short period of time. These changes have taken place within a framework of processes referred to respectively as demographic transition and epidemiological transition. This study is aimed at providing evidence as to the demographic transition and epidemiological transition which took place in this country within the 1960-2001 period. METHODS: This is a time-series study gathering demographic and death rate-related information from Chile throughout the 1960-2001 period. The data was taken from the Demographic Yearbooks of the National Institute of Statistics, from information produced by the Department of Prospective Studies under the Ministry of Planning and Cooperation and the Chilean Ministry of Health. RESULTS: In 1960, 39.6% of the population had less than 14 years old, natality rate was 36.3 per 1000, general mortality rate 12.3 per 1000 and Infant Mortality rate 120 per 1000. 44% of causes of decreases were by infectious and newborn's diseases. In 2001, 28% of the population has less than 14 years old, natality rate is 18.3 per 1000, General Mortality rate 5.4 per 1000 and Infant Mortality rate 8.9 per 1000. 68% of causes of diseases are by chronic diseases. CONCLUSIONS: Based on the results, it can be said that Chile is currently in a late stage of demographic transition as well as epidemiological transition. Ascertaining Chile's actual situation will provide information to those Latin American countries which are currently in early stages of these types of transitions.

Adolescent↗

PubMed1989

The demographic evolution of human populations: the role of selection and environmental factors.

Selection (genetic and cultural) and environmental variation are the principal mechanisms determining patterns of demographic change in human populations. Conditions exist under which the nature and intensity of these forces can be inferred from temporal trends in the demographic variables. These conditions, which can be expressed in terms of relations between the Malthusian parameter and population entropy, provide a means for evaluating the effect of selective and nonselective factors on demographic trends in human populations. The distinction between the roles of selection and environmental factors is illustrated by a study of the demographic transition in Sweden (1778-1965). This study shows that demographic changes during the pre- and posttransitional phases are determined mainly by environmental factors, whereas the changes during the transitional phase are mainly due to cultural selection. This analysis provides, for all three phases of the demographic transition, quantitative measures of the intensity of the forces (selective and nonselective) acting on both mortality and fecundity distributions.

Anthropology, Cultural↗