[The demographic factor in the global model].
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Conservation of Natural Resources↗
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Results for “Demographic modelling”
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The spread of HIV-1 in Africa: sexual contact patterns and the predicted demographic impact of AIDS.
The spread of HIV-1 in Africa is examined here in the light of recent information on the main epidemiological and behavioural determinants of transmission. Mathematical models incorporating demographic, epidemiological and behavioural processes are used to assess the potential demographic impact of the disease AIDS. These analyses highlight the significance of patterns of sexual behaviour, and in particular networks of sexual contact, on the predicted spread of infection. Current data reveal substantial variations in the degree of spread between and in countries, but new analyses support earlier predictions that in the worst-afflicted areas AIDS is likely to change population growth rates from positive to negative values in a few decades.
Acquired Immunodeficiency Syndrome↗
Time to death and health expenditure: an improved model for the impact of demographic change on health care costs.
BACKGROUND: Obtaining well-founded estimates of the effect of demographic change on future health expenditures is a pressing issue in all developed countries. Thus far, expenditure projections have examined the effect of age on health care costs, but fail to account for the influence of remaining life expectancy on costs. OBJECTIVE: This paper seeks to create a more accurate projection model that considers the concentration of costs towards the end of life, and to compare this model with the more traditional approach that holds age- and sex-specific per capita expenditures constant. METHODS: We used a longitudinal hospital dataset which followed 90 929 patients aged 65 and older from 1970 to death, to create an economic model of hospital costs based on patient age and time remaining to death. We then applied the model to England population projections to predict the effect of demographic changes on hospital expenditures from 2002 to 2026. RESULTS: The decline in age-specific mortality rates over time postpones death to later ages, pushing back death-related costs. Accounting for this in expenditure projections gave a predicted annual growth rate of 0.40%-half of the rate predicted with a traditional method. CONCLUSIONS: Using richer data and more refined methods than have hitherto been employed, this study strongly confirms that the pressure of population increases and ageing demographic structure on hospital expenditures will be partially countered by the postponement of death-related hospital costs to later in life-a finding consistent with emerging epidemiological evidence, and heartening for policy makers and physicians alike.
Adolescent↗
[Economic decisions within the family and key demographic variables: a simultaneous equations model for Chile].
The extent to which a theory of family decisions (in which fertility behavior and family size are based on family's economic interests) can be applied to data for Chile is examined. Data for the period 1960-1985 concerning fertility and infant mortality are used. "The structure is a four equation relation: one for the birth rate, one for infant mortality rate, one for the rate of the participation of women in the labor market, and the last one, used as auxiliary for the per capita income." The results confirm the validity of the theory. (SUMMARY IN ENG)
Americas↗
Homoploid Hybrid Speciation in a Marine Pelagic Fish.
Homoploid hybrid speciation (HHS) is an enigmatic evolutionary process where new species arise through hybridisation of divergent lineages without changes in chromosome number. Although increasingly documented in various taxa and ecosystems, convincing cases of HHS in marine fishes have been lacking. This study presents a possible case of HHS in a pelagic marine fish based on comprehensive genomic, morphological, and ecological analyses. Population genomics, species tree estimation, and tests of introgression and admixture identified three sympatric clusters in Megalaspis cordyla in the western Pacific and the admixed nature of one cluster between the others. Moreover, model-based demographic inference favoured a hybrid speciation scenario over introgression for the origin of the admixed cluster. While contemporary gene flow suggested partial reproductive isolation, examination of occurrence data and ecologically relevant morphological characters suggested ecological differences between the clusters, potentially contributing to the reproductive isolation and niche partitioning in sympatry. The clusters are also morphologically distinguishable and thus can be taxonomically recognised as separate species. The hybrid cluster is restricted to the coasts of Taiwan and Japan, where all three clusters coexist. The parental clusters are additionally found in lower latitudes, where they display non-overlapping distributions. Given the geographical distributions, estimated times of species formation, and patterns of historical demographic changes, we propose that the Pleistocene glacial cycles were the primary driver of HHS in this system. We also develop an ecogeographic model of HHS in marine coastal ecosystems, including a novel hypothesis to explain the initial stages of HHS.
Animals↗
United States Census 2000 population with bridged race categories.
OBJECTIVES: The objectives of this report are to document the methods developed at the National Center for Health Statistics (NCHS) to bridge the Census 2000 multiple-race resident population to single-race categories and to describe the resulting bridged race resident population estimates. METHOD: Data from the pooled 1997-2000 National Health Interview Surveys (NHIS) were used to develop models for bridging the Census 2000 multiple-race population to single-race categories. The bridging models included demographic and contextual covariates, some at the person-level and some at the county-level. Allocation probabilities were obtained from the regression models and applied to the Census Bureau's April 1, 2000, Modified Race Data Summary File population counts to assign multiple-race persons to single-race categories. RESULTS: Bridging has the most impact on the American Indian and Alaska Native (AIAN) and Asian or Pacific Islander (API) populations, a small impact on the Black population and a negligible impact on the White population. For the United States as a whole, the AIAN, API, Black, and White bridged population counts are 12.0, 5.0, 2.5, and 0.5 percent higher than the corresponding Census 2000 single-race counts. At the sub-national level, there is considerably more variation than observed at the national level. The bridged single-race population counts have been used to calculate birth and death rates produced by NCHS for 2000 and 2001 and to revise previously published rates for the 1990s, 2000, and 2001. The bridging methodology will be used to bridge postcensal population estimates for later years. The bridged population counts presented here and in subsequent years may be updated as additional data become available for use in the bridging process.
Censuses↗
[Demographic impact of AIDS mortality in France in 1990: AIDS before suicide and next to traffic accidents].
This paper presents an evaluation of the demographic impact of mortality by AIDS in the next future years, in France. Future cases are predicted by using a regression technique based on an exponential model. Three demographic indicators are computed: Years of Potential Life Lost (YPLL), Expectancy of Life (EL) and Expectancy of Active Life (EAL) for males. For example, in 1990 AIDS would be responsible of a loss of 0.67 and 0.38 years for EL and EAL respectively. These results would raise AIDS almost to the Accidents level and ahead of Suicide. Moreover, we consider that the estimations presented in this article are rather optimistic, taking into account the fact that there is an increasing proportion of IV drug abusers cases, younger than the other cases.
Accidents, Traffic↗
Demographic and cardiovascular risk factors in relation to antioxidant status: the EVA Study.
The aim of the study was to examine the determinants of blood antioxidant indicators on a large sample. Levels of plasma selenium and carotenoids, vitamin E in red blood cells, and thiobarbituric acid reactive substances (TBARS) were determined. The cross-sectional relationships between these markers and demographic and cardiovascular risk factors were examined in participants of the EVA study, a cohort of 1389 men and women, aged 59-71 years. Multivariable regression models including demographic (age, sex, socio-economic level), lifestyle (alcohol, tobacco), clinical and metabolic (lipids, glycemia) factors were used. Women had higher levels of plasma carotenoids, TBARS and red blood cell vitamin E. Cholesterol levels were positively associated to lipid-soluble vitamins, selenium and TBARS. Use of lipid-lowering drugs was positively associated with selenium and vitamin E and negatively with carotenoids. Body mass index was the strongest determinant of plasma carotenoids. Education and income levels were positively associated with selenium and total carotenoids. Tobacco consumption was negatively associated with red blood cell vitamin E, whereas alcohol consumption was positively associated with TBARS. This study emphasizes the respective place of the various determinants of antioxidant status. When considering tissue antioxidant indicators, analyses should take into account not only the metabolic parameters but also socio-economic factors and the subject's life style.
Aged↗
Modeling the HIV/AIDS epidemic in the English-speaking Caribbean.
The study reported here examines the past and potential future impact of HIV/AIDS in 19 nations of the primarily English-speaking Caribbean. The authors use DemProj, a demographic projection model, to explore two different HIV scenarios. In the low scenario adult HIV prevalence stabilizes at 2% in the year 2000, and in the high scenario adult HIV prevalence stabilizes at 5%. By the year 2010, annual AIDS incidence exceeds 11,000 cases in the low scenario and 28,000 in the high scenario. In both scenarios, 70% of the cases are in young adults 20-45 years old and 12% are in children 0-15. Age-specific mortality is more than doubled in the 20-40 age range in the low scenario, and more than quadrupled in the high scenario. The impact on death rates is also severe among children 0-10. In assessing the economic impact, the authors estimate that the total annual costs of the epidemic will approach US$ 500 million (in constant 1989 US$) or 2% of GDP in the low scenario, and will exceed US$ 1,200 million or 5% of GDP in the high scenario.
Acquired Immunodeficiency Syndrome↗
Nonlinearity in demographic and behavioral determinants of morbidity.
OBJECTIVE: To examine nonlinearity of determinants of morbidity in the United States DATA SOURCES: A secondary analysis of data on individuals with dietary data from the Cancer Epidemiology Supplement and National Health Interview Survey (NHIS) 1987, a cross-sectional, stratified random sample of the U.S. population (n = 22,080). STUDY DESIGN: A statistical exploration using additive multiple regression models. METHODS: A Morbidity Index (0-30 points), derived from 1987 National Health Interview Survey data, combines number of conditions, hospitalizations, sick days, doctor visits, and degree of disability. Behavioral (health habits) variables were added to multivariate models containing demographic terms, with Morbidity Index and Self-assessed Health outcomes (n = 17,612). Tables and graphs compare models of morbidity with self-assessed health models, with and without behavioral terms. Graphs illustrate curvilinear relationships. PRINCIPAL FINDINGS: Morbidity and health are associated nonlinearly with age, race, education, and income, as well as alcohol, diet change, vitamin supplement use, body mass index (BMI), marital status/living arrangement, and smoking. Diet change and supplement use, education, income, race/ethnicity, and age relate differently to self-assessed health status than to morbidity. Morbidity is strongly associated with income up to about dollars 15,000 above poverty. Additional income predicts no further reduction in morbidity. Better health is strongly related to both higher income and education. After controlling for income, black race does not predict morbidity, but remains associated with lower self-assessed health. CONCLUSIONS: Good health habits, as captured in these models, are associated with a 10-20-year delay in onset and progression of morbidity.
Adolescent↗
Environmental correlates of physical activity in a sample of Belgian adults.
PURPOSE: This study investigated the variance in sitting, walking, and moderate and vigorous physical activity explained by neighborhood design and recreational environmental variables above and beyond the variance accounted for by individual demographic variables. DESIGN: Cross-sectional analyses of self-reported survey data. SETTING: A random sample of inhabitants of Ghent, Belgium, aged 18-65 years, was drawn. SUBJECTS: Five hundred twenty-one adults completed questionnaires (52.1% response rate). The average age of the sample was 41 years, and 48.2% were female. MEASURES: A questionnaire developed to assess neighborhood design and recreational environmental variables with a total of 81 items was administered. The environmental questionnaire showed acceptable to good reliability and acceptable validity. The previously validated International Physical Activity Questionnaire (IPAQ) was used to quantify physical activity in the past 7 days. Additional demographic information was also obtained. RESULTS: Regression analyses showed that environmental variables were related to all types of physical activity in both sexes. However, the range of variance explained by the models including demographic and environmental variables was low, only 5% to 13%. Minutes of walking and of moderate-intensity activity were related to quality of sidewalks and accessibility of shopping and public transportation. Vigorous physical activity was related to presence of activity supplies in the home and number of convenient activity facilities outside the home. CONCLUSIONS: Both neighborhood design and recreational environment variables had small but significant associations with multiple types of physical activity in a sample of Belgian adults.
Adolescent↗
Population growth and income growth during the demographic transition: does a Malthusian model help explain their relationship?
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Demography↗
Slow-fast dynamics in a model of population and resource growth.
"Models of the interaction of population, the economy, and the environment often contain nonlinear functional relationships and variables that move at different speeds. These properties foster apparent unpredictabilities in system behaviour. Using a simple deterministic model of demographic, economic and environmental interactions we illustrate the usefulness of geometric singular perturbation theory in environmental population economics. In contrast to local stability analysis, the theory of slow-fast dynamics helps to gain new insights into the global behaviour of the system. In particular, the knowledge of the basins of attraction of the stationary states enables one to determine the regions of sustainable future paths of resources and population." (SUMMARY IN FRE)
Conservation of Natural Resources↗
Serial coalescent simulations suggest a weak genealogical relationship between Etruscans and modern Tuscans.
The Etruscans, the only preclassical European population that has been genetically characterized so far, share only two haplotypes with their modern geographic counterparts, the Tuscans, who, nonetheless, appear to be their closest relatives. We modeled 10 demographic scenarios spanning the last 2,500 years and tested by serial coalescent simulation whether any are consistent with the patterns of genetic diversity observed within and between the Etruscan and the modern Tuscan populations. Models in which the Etruscans are the direct ancestors of modern Tuscans appear compatible with the observed data only when they also include a very high mutation rate and an ancient founder effect. A better fit was obtained when the ancient and the modern samples were extracted from two independently evolving populations, connected by little migration. Simulated and observed parameters were also similar for a scenario in which the ancient samples came from a subset, e.g., a social elite, genetically differentiated from the bulk of the Etruscan population. In principle, these results may be biased by factors such as gross and systematic errors in the ancient DNA sequences and failure to sample suitable modern individuals. If neither proves to be the case, this study strongly suggests that either the mitochondrial mutation rate is much higher than currently believed or the Etruscans left very few modern mitochondrial descendants.
Biological Evolution↗
Substitution rate variation among sites in mitochondrial hypervariable region I of humans and chimpanzees.
Mitochondrial D-loop hypervariable region I (HVI) sequences are widely used in human molecular evolutionary studies, and therefore accurate assessment of rate heterogeneity among sites is essential. We used the maximum-likelihood method to estimate the gamma shape parameter alpha for variable substitution rates among sites for HVI from humans and chimpanzees to provide estimates for future studies. The complete data of 839 humans and 224 chimpanzees, as well as many subsets of these data, were analyzed to examine the effect of sequence sampling. The effects of the genealogical tree and the nucleotide substitution model were also examined. The transition/transversion rate ratio (kappa) is estimated to be about 25, although much larger and biased estimates were also obtained from small data sets at low divergences. Estimates of alpha were 0.28-0.39 for human data sets of different sizes and 0.20-0.39 for data sets including different chimpanzee subspecies. The combined data set of both species gave estimates of 0.42-0.45. While all those estimates suggest highly variable substitution rates among sites, smaller samples tend to give smaller estimates of alpha. Possible causes for this pattern were examined, such as biases in the estimation procedure and shifts in the rate distribution along certain lineages. Computer simulations suggest that the estimation procedure is quite reliable for large trees but can be biased for small samples at low divergences. Thus, an alpha of 0.4 appears suitable for both humans and chimpanzees. Estimates of alpha can be affected by the nucleotide sites included in the data, the overall tree length (the amount of sequence divergence), the number of rate classes used for the estimation, and to a lesser extent, the included sequences. The genealogical tree, the substitution model, and demographic processes such as population expansion do not have much effect.
Animals↗
The effect of integrating substance abuse treatment with prenatal care on birth outcome.
OBJECTIVE: To determine whether engaging pregnant substance abusers in an integrated program of prenatal care and substance abuse treatment would improve neonatal outcomes. STUDY DESIGN: The subjects were women who voluntarily enrolled in Project Link, an intensive outpatient substance abuse treatment program at Women and Infants Hospital, Providence, RI. A total of 87 women received substance abuse treatment in conjunction with their prenatal care; the comparison group of 87 women received equivalent prenatal care but did not enroll in the substance abuse treatment program until after they delivered. The two groups of women were similar demographically and socioeconomically and had similar substance abuse histories. Univariate and multivariate analyses were performed. The key outcomes were gestational age at delivery, birth weight, preterm delivery, Apgar scores, and neonatal intensive care admission rate. Factors controlled in the multivariate models included demographics, socioeconomic status, parity, and prenatal care. RESULTS: Infants born to women who enrolled prenatally were 400 gm heavier (p < 0.001), and their gestational age was 2 weeks longer (p < 0.001) than infants of mothers enrolled postpartum. In addition, they were approximately one-third as likely to be born with a low birth weight (p < 0.01) and approximately one-half as likely to be admitted to the neonatal intensive care unit (p < 0.05). CONCLUSION: Neonatal outcome is significantly improved for infants born to substance abusers who receive substance abuse treatment concurrent with prenatal care compared with infants born to substance abusers who enter treatment postpartum.
Adolescent↗
Determinants of subjective quality of life in patients attending community-based mental health services. The South-Verona Outcome Project 5.
OBJECTIVE: Investigate the relationship of various domains of quality of life (QoL) with socio-demographics, clinical and social characteristics, service use and satisfaction in a representative sample of patients in contact with the South-Verona community mental health service. METHOD: Measures included: Lancashire Quality of Life Profile (LQOLP), demographics, diagnosis and service utilization data from the Case Register, Brief Psychiatric Rating Scale (BPRS), Disability Assessment Schedule (DAS), Global Assessment of Functioning (GAF) and Verona Service Satisfaction Scale (VSSS). Analyses were conducted using a block-stratified multiple regression model. RESULTS: Demographics, diagnosis, psychopathology, disability, functioning and service use together explained different amounts of variance in each LQOLP domain, but always less than 14%. VSSS explained more variance than any other indicator in health (13.1%), social relations (12.1%), leisure/participation (9.1%), and general wellbeing (9.0%). CONCLUSION: Different domains of QoL are predicted by different indicators. In some important domains, self-perceived satisfactory and effective care might have an impact on the QoL of patients.
Adult↗
[Demographic relationships between generations and models derived from them].
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Age Distribution↗