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At least 793 records · Page 44Linked to original sources
PubMed1982

Demographic disaggregation in the construction of regional econometric models: a statistical evaluation.

"A cohort-component method is used to construct historical annual age/sex disaggregations of total population. In econometric models of six substate areas [in the United States], regressions are estimated with and without the disaggregated data for five model variables expected to be dependent on the size of particular population subgroups. Statistical tests are performed to determine significant differences in residual variance of estimation with and without the disaggregated data. Although age/sex population projections may be a desired model output per se, the results indicate that the population subgroup data generally do not improve estimation of other model variables." (summary in FRE, ITA, JPN, )

Age Distribution↗
PubMed2001

Interstitial lung diseases: an epidemiological overview.

Epidemiological studies on interstitial lung diseases (ILDs) may be schematically subdivided into the following major types: 1) quantifications of disease, broken down into incidence, prevalence and mortality data; 2) identification of aetiological factors; and 3) clinical epidemiological studies. Epidemiological data may be obtained from different sources or population groups, using different study designs such as systematic national statistics, population-based data and registries, and large case series of specific diseases. Differences in results between epidemiological studies may be due to real differences in incidence, but may also be due to changes in disease definitions and classifications, differences in the epidemiological design of the studies, or even registration bias. Comparative epidemiological data of different ILDs are almost limited to the general population study in Bernalillo County and to national mortality statistics, which should be interpreted with great caution. Also, some, mostly national registries of the different ILDs have been carried out by specific medical profession groups (especially pulmonologists), which clearly underestimate the real incidence of ILDs, but in which the comparison of the relative frequencies is probably accurate. Based on all these comparative studies, sarcoidosis and idiopathic pulmonary fibrosis appear to be the most frequent ILDs, followed by hypersensitivity pneumonitis and ILD in collagen vascular disease, when classical pneumoconioses are not included. There is also a relatively large group of nonspecific fibrosis. Much more data have been published on the epidemiology of specific forms of interstitial lung disease. Most information is available on the epidemiology of sarcoidosis, and those data are probably the most accurate. Data on idiopathic pulmonary fibrosis have the disadvantage of the recent changes in definition and classification of this disease. Hypersensitivity pneumonitis has been studied epidemiologically, especially in some exposure groups such as farmers and pigeon breeders, and in some regions in North America, UK, France and Scandinavia. Estimates of frequencies of interstitial lung disease in collagen vascular disease or of drug-induced interstitial lung disease are less accurate and more variable, depending on diagnostic criteria. Notwithstanding the aforementioned problems, this report tries to provide a balanced overview of the epidemiology of different interstitial lung diseases.

Humans↗
PubMed1992

Demography of the Hadza, an increasing and high density population of Savanna foragers.

This is a report on the demography of the Hadza, a population of East African hunter-gatherers. In it, we describe the results of a census, and our estimation of age structure, survivorship, mean age of women at childbearing, number of live children, total population size and density, and rate of change since 1967. We show that relevant measures fit closely the stable population model North 6 chosen by Dyson to represent Hadza demography in the 1960s. We compare aspects of Hadza demography with surrounding non-Hadza and with the !Kung. Among other things, we find that the Hadza have a higher population density, higher fertility, and a faster population growth rate than do the !Kung. These demographic differences are consistent with our expectations, which were based on differences in the costs and benefits of foraging in the two regions. We also show that Hadza demographic parameters display remarkable consistency over the past 20 years. Since neighboring populations have been encroaching on the area used by the Hadza, and Hadza foragers have been subject to interludes of externally imposed settlement, this consistency is surprising. We discuss some of the implications.

Adolescent↗
PubMed2005

Population genetic structure of the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis): implications for management and conservation.

Understanding the population genetic structure is a prerequisite for conservation of a species. The degree of genetic variability characteristic of the mitochondrial DNA control region has been widely exploited in studies of population genetic structure and can be useful in identifying meaningful population subdivisions. To estimate the genetic profile of the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), an endangered freshwater population endemic to China, the complete mtDNA control region was examined in 39 individuals belonging to seven different stocks inhabiting the middle and lower reaches of the Yangtze River. Very low genetic diversity was found (nucleotide diversity 0.0011 +/- 0.0002 and haplotypic diversity 0.65 +/- 0.05). The mtDNA genetic pattern of the Yangtze population appears to indicate a founder event in its evolutionary history and to support the marine origin for this population. Analyses by Fst and phi(st) yielded statistically significant population genetic structure (Fst = 0.44, P < 0.05; phi(st) = 0.36, P < 0.05). These results may have significant implications for the management and conservation of the Yangtze finless porpoise in the future.

Animals↗
PubMed1992

Workload in oral and maxillofacial surgery: analysis of time trends from linked statistics in a defined population.

Data from the Oxford Region were used to study trends in hospital admission rates and demographic profiles of hospital care in the National Health Service in oral and maxillofacial surgery. In a defined population of 1.9 million people, admission rates for inpatient care, day case care, and outpatient attendance rates all almost doubled between 1975-1985. Population-based age-specific admission rates were much higher in teenagers and young adults than in other age-groups. In these age-groups admission rates for females were about double those for males. Whilst perhaps not surprising to the oral and maxillofacial surgeon, these demographic profiles of workload are strikingly different from those found in most other hospital specialties.

Adolescent↗
PubMed1996

Modelling urban-rural population growth in China.

"The population of China is still growing despite a dramatic decline in fertility in the past two decades. There are marked urban-rural differentials in fertility and, as a result, the pace of urbanization has significant effects on population growth. In this research an attempt is made to model urban-rural population growth in China. A demoeconomic model of urban and rural sectors is calibrated to account for the long-term trend of urbanization in China.... An accounts-based urban-rural population model, in which rural to urban migration and transition are driven by the foregoing demoeconomic model, is established.... These models are used to make urban-rural population projections for the period 1988-2087 under various fertility rate assumptions."

Asia↗
PubMedDate not supplied

Individual aging and mortality rate: how are they related?

Many researchers working in the area of aging and longevity base their conclusions on the behavior of empirical age trajectories of mortality rates. In such analyses, changes in the slope of the logarithm of the mortality curve are often associated with changes in the rate of individual aging. We show that such interpretation may be incorrect: the changes in the slope of this curve do not necessarily correspond to the changes in the rate of individual aging. We use three models of mortality and aging to illustrate this statement. The first one is based on the idea of frailty. We show that changes in frailty distribution alone may be responsible for changes in the slope. The second model exploits the idea of saving lives. It evaluates changes in mortality rate after elimination of lethal stressful events. The third model uses the idea of Strehler and Mildvan (1960). It shows that changes in the rate of individual aging may take place without changes in the slope of the logarithm of the mortality curve.

Aging↗
PubMed1987

Microcomputer package for statistical analysis of microbial populations.

We have developed a Pascal system to compare microbial populations from different ecological sites using microcomputers. The values calculated are: the coverage value and its standard error, the minimum similarity and the geometric similarity between two biological samples, and the Lambda test consisting of calculating the ratio of the mean similarity between two subsets by the mean similarity within subsets. This system is written for Apple II, IBM or compatible computers, but it can work for any computer which can use CP/M, if the programs are recompiled for such a system.

Algorithms↗
PubMed1993

Estimation of the intrinsic rate of natural increase and its error by both algebraic and resampling approaches.

The intrinsic rate of natural increase or Malthusian parameter plays a key role fields as diverse as ecology, genetics, demography and evolution. It characterizes the growth of a population in a determinate environment. Since its rigorous statistical estimation requires of intensive calculation, the use of a computer becomes essential. The two main approaches to the calculation of the Malthusian parameter, its error and confidence intervals have been implemented in a program and have been compared by means of an example.

Algorithms↗
PubMed2003

Selection in a subdivided population with local extinction and recolonization.

In a subdivided population, local extinction and subsequent recolonization affect the fate of alleles. Of particular interest is the interaction of this force with natural selection. The effect of selection can be weakened by this additional source of stochastic change in allele frequency. The behavior of a selected allele in such a population is shown to be equivalent to that of an allele with a different selection coefficient in an unstructured population with a different size. This equivalence allows use of established results for panmictic populations to predict such quantities as fixation probabilities and mean times to fixation. The magnitude of the quantity N(e)s(e), which determines fixation probability, is decreased by extinction and recolonization. Thus deleterious alleles are more likely to fix, and advantageous alleles less likely to do so, in the presence of extinction and recolonization. Computer simulations confirm that the theoretical predictions of both fixation probabilities and mean times to fixation are good approximations.

Alleles↗