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PubMed1991

A nonparametric approach to analyzing large human populations.

There are many statistical techniques that require the assumption that the population being studied is normally distributed--regression analysis, multivariate analysis, time series analysis, and so on. Unfortunately, as the development of survey sampling has long acknowledged, large human populations are usually stratified into several different subpopulations. Since the boundaries between the strata are somewhat blurred, they are not independent, so the overall distribution of the population tends to be multimodal rather than normal. In this paper, a technique is developed to find these multimodal techniques using nonparametric density estimation. Its effectiveness is demonstrated by means of an example.

Analysis of Variance↗
PubMed1993

A unified approach to study hypervariable polymorphisms: statistical considerations of determining relatedness and population distances.

Relatedness between individuals as well as evolutionary relationships between populations can be studied by comparing genotypic similarities between individuals. When hypervariable loci are used to describe genotypes, it is shown that both of these problems can be approached with a unified theory based on allele sharing between individuals. The distributions of the number of shared alleles between individuals indicate their kin relationships. Extending this, we obtain statistics for genetic distances between populations based on average number of alleles shared between individuals within and between two different populations. Traditional statistical inferential procedure can be used to establish specific kinship relationships between individuals. We derive estimates of the number of hypervariable loci needed for a specified reliability of such an inference. Evolutionary dynamics of genetic distance statistics based on allele sharing is also studied. It shows that such measures of genetic distances remain linear with the time of divergence for a period comparable to that of the gene frequency-based measures of genetic distances. Statistical properties of measures based on allele sharing establish that for using such summary statistics it is not necessary to know the full characteristics of all loci used. It is enough to know the degree of heterozygosity per locus and the number of loci. Therefore, in principle, this approach can also be used for DNA fingerprinting data in the studies of relatedness between individuals as well as between populations. The possible compromising features of multilocus DNA fingerprinting data are also discussed.

Alleles↗
PubMed2001

Microsatellite variation in natural Drosophila melanogaster populations from New South Wales (Australia) and Tasmania.

Microsatellite variation was studied at 48 microsatellite loci in 10 Drosophila melanogaster populations to investigate the population structure on the Australian east coast. Low, but statistically significant population differentiation was observed among most populations. The populations on the Australian mainland did not show evidence for isolation by distance. We conclude that the population structure of D. melanogaster on the Australian mainland is probably the result of a shared history (recent colonization). The observed differences between local D. melanogaster populations probably reflect variation in effective population sizes rather than patterns of gene flow. Two populations from Tasmania were more differentiated from the Australian mainland than a population from Israel, raising the question whether they are derived from the Australian mainland or colonized from a different source population.

Animals↗
PubMed1991

Intraspecific variation in population gene diversity and effective population size correlates with the mating system in plants.

Published data on allele frequencies at isozyme loci in inbreeding and outbreeding plant species were analyzed to examine intraspecific variation in gene diversity and effective population size (Ne). Compared with outbreeders, inbreeding species showed markedly greater variation among populations in average values of Nei's gene diversity statistic. Effective population size was estimated by assuming that the variation observed at isozyme loci is selectively neutral. Inbreeding species showed greater levels of variation in Ne than did outbreeders, although the upper range of Ne was similar in the two classes of species. The results suggest that there may be considerable genetic variation and potential for evolutionary change in some but not all populations of inbreeders. Moreover, these findings are important with respect to the conservation of genetic resources. In particular, that the amount of intraspecific variation in population genetic diversity and Ne differs between inbreeding and outbreeding species should be taken into account in sampling efforts designed to optimize the diversity of germplasm collections.

Journal Article↗
PubMed2004

Regional population structure of a widely introduced estuarine invertebrate: Nematostella vectensis Stephenson in New England.

Nematostella vectensis is an infaunal anemone occurring in salt marshes, lagoons and other estuarine habitats in North America and the United Kingdom. Although it is considered rare and receives protection in England, it is widely distributed and abundant in the United States, particularly along the Atlantic coast. Recent studies suggest that both anthropogenic dispersal and reproductive plasticity may significantly influence the genetic structure of N. vectensis populations. Amplified fragment length polymorphism (AFLP) fingerprinting of individuals from nine populations in the northeastern United States indicates that stable populations are maintained by both asexual and sexual reproduction; in some cases asexually reproducing lineages exist within sexually reproducing populations. F statistics reveal extraordinarily high degrees of genetic differentiation between populations, even those separated by very short distances (less than 100 m). Genetic distances show little to no correlation with geographical distances, consistent with a role for sporadic, geographically discontinuous dispersal coupled with limited gene flow. No single genotype was found at more than one site, despite apparent homogeneity of habitat. In contrast with reported genotypic distributions for Nematostella in the United Kingdom, where a single clonal genotype dominates at multiple sites through southern England, our data thus fail to support the hypothesis of a general-purpose genotype in the northeastern United States. However, they are consistent with important roles for reproductive plasticity, sporadic introductions and complex local population dynamics in determining the global and regional distribution of this species.

Analysis of Variance↗
PubMed2002

The importance of weight-normalized exposure data when issuing fish advisories for protection of public health.

Public health protection from environmental contaminants requires an understanding of the extent of contamination and of the extent of exposure to the contamination. My argument here is that weight-normalized, species-specific, individual-consumption pattern data are vital for determining exposure levels used to ascertain health protection measures and impacts from consuming contaminated fish. This study demonstrates the importance of adequate consumption pattern data for determining exposure distributions used for public health protection by examining three populations exposed to methylmercury through fish consumption: one recreational angler population and two Native-American populations. I compared exposure distributions derived from empirically derived species-specific, individual-consumption data from the three populations and exposure distributions derived, in part, from summary statistics for populations. In so doing, I conducted sensitivity analyses and population-specific probabilistic assessments of exposure. Although the goals of present-day accepted practices--using exposure distributions derived partly from point-estimate-based consumption and body-weight values--are laudable, results presented here indicate that weight-adjusted intake values for a population of concern are warranted when determining exposure distributions and should not be neglected in a health assessment instigated by available data on contaminant concentrations. If individual intake data are unobtainable, raw data from similar populations or tabulated values providing contaminant intake normalized for body weight may be viable alternatives to default values, and can be used to adequately protect public health. Without weight-normalized consumption pattern data to determine exposure, health assessment conclusions can mislead the public and have diminishing protective value.

Animals↗
PubMed2002

[Analysis of three Y-STR loci polymorphism in isolated populations].

OBJECTIVE: To figure out the polymorphism of three Y-STR loci in isolated populations and explore the consanguinity of the populations with the use of Y-STR. METHODS: Male samples were selected from two isolated populations(80 and 60 males) in Zhejiang province and one open population (36 males), genescan was performed with males' DNA by genescan technology with ABI PRISM 377 sequencer at Y chromosome loci DYS388, DYS390 and DYS395. RESULTS: DYS388, DYS390, DYS395 allele counts in Yushan island population, Taohua island population and open population were 8, 9, 7, 5, 6, 7 and 6, 6, 5 respectively. Gene diversity was between 0.70-0.80 in the three populations. There was no difference in distribution of allele frequency and shared genotypes between the isolated populations and the open population by statistical test. Genetic distance is long between Taohua island population and open population, short between Yushan island population and open population, and moderate between Yushan island population and Taohua island population. CONCLUSION: The main allele is 129 at DYS388; 215 at DYS390; and 119 at DYS395. The distribution of allele frequency and gene diversity at DYS388, DYS390, DYS395 loci, and the shared genotypes between populations as well as the genetic distance are unable to explain the blood relationship between the isolated and open populations, suggesting the additional studies in large sample size will be necessary to use Y-STR for exploring the blood relationship between populations.

Alleles↗
PubMed1988

Decree No. 96.705 on performance of the Tenth General Census of Brazil, 15 September 1988.

This Decree provides that the Tenth General Census of Brazil, to be undertaken in 1990 by the Brazilian Institute of Geography and Statistics, is to include a) a demographic census (of population and domicile); b) a census of farming and cattle raising; c) an industrial census; d) a commercial census; and e) a census of services. Further provisions of the Decree set forth the powers of the Institute, the dates of the various censuses, and the duty of other government organizations to give assistance to the Institute.

Agriculture↗
PubMed2006

[Proximal femur fractures in the elderly in The Netherlands during the period 1991-2004: incidence, mortality, length of hospital stay and an estimate of the care capacity needed in the future].

OBJECTIVE: To assess the incidence of operations for neck and pertrochanteric femur fractures during the last 15 years and to estimate the future demand for such operations in The Netherlands. DESIGN: Retrospective. METHOD: For the years 1991, 1995, 2000 and 2004, the following anonymised data were collected in the National Medical Registry of Prismant for all patients admitted to Dutch hospitals for a hip fracture: age-group, gender, length of pre- and postoperative hospital stay, destination after discharge and hospital mortality. These data were related to demographic data for the Dutch population from Statistics Netherlands (CBCS) and to estimates for the Dutch population in the future from Primos Prognostic Data. RESULTS: The average absolute increase in the period 1991-2004 was linear, with 230 fractures per year. Women were operated for a hip fracture 1.5-2 times as often as men in the same age range. The age-specific incidence remained constant over the years but the absolute number of elderly persons per age group increased. The average length of pre- and postoperative hospital stay was reduced by half during the period under investigation. The postoperative hospital mortality decreased from 8.1% in 1991 to 5.6% in 2004, and was 1.5 times as high for men aged 70 years or over as for women of the same age group. In 2004 as compared to 1991, 2.5 times as many patients were discharged to a nursing home. In view of the increasing age of the population, the total number of operated hip fractures can be expected to be 20,200 in the year 2010 and 23,900 in the year 2020. CONCLUSION: In the period 1991-2004 there was an annual increase of 230 operations for proximal femur fractures that was closely related to the ageing of the Dutch population. During the years under investigation, the incidence in the same age range was higher in women, but men had a higher hospital mortality. It is estimated that the decreasing hospital mortality and the decrease in the length of hospital stay will increase the need for nursing-home care for this category of patients.

Accidental Falls↗
PubMedDate not supplied

Cytology of ganglioglioma of the brain: a morphometric study.

This study describes and illustrates the application of the morphometric method in the classification of different types of cells in mixed populations. The nuclei of neoplastic cell and astrocytes, nonneoplastic monocytoid cells and lymphocytes in touch preparations of two gangliogliomas were measured. Two preoperative cerebrospinal fluid specimens from one of these cases were similarly evaluated. The mean nuclear area of some cell populations was statistically distinct and consistent in each preparation. Other cell populations showed considerable overlap in nuclear size and could not be separated on the basis of this parameter alone.

Astrocytes↗
PubMed1989

Trends in perinatal and neonatal mortality and morbidity in India.

Although the infant mortality rate (IMR) has reduced by 50% during the past century, it compares poorly with the advanced countries and some developing countries. The observed fall in IMR has been mostly in post-neonatal mortality, with the result that neonatal deaths now account for over 60% of all infant deaths. The overall perinatal mortality rate (PMR) in India is still over 50 per 1000 and has shown virtually no decline during the past decade, However, PMR differs widely in different states, urban/rural areas, different hospitals and so on. PMR is seen to correlate better with social development than economic development of the representative community. The causes of perinatal deaths suggest poor health of mother and poor health facilities and are hence potentially preventable. Various studies have shown that PMR can be significantly reduced within a short span of time. The registration of vital statistics continue to be highly unsatisfactory especially in rural areas.

Cause of Death↗
PubMed2003

Hitchhiking mapping--functional genomics from the population genetics perspective.

Several statistical tests based on population genetic theory are used to identify genes that have recently acquired a beneficial mutation. Here, I describe the extension of these tests to a multilocus approach for a genome-wide survey for genes that have been under recent positive selection. As this strategy could potentially identify genes with weak phenotypic effects, it will be very useful in population genetic approaches aimed at understanding adaptation processes in natural populations. Furthermore, this 'hitchhiking mapping' could also help in the functional characterization of genomes.

Animals↗
PubMed2006

Health-related quality of life in chronic coagulation disorders.

Measurement of health-related quality of life (HR-QoL) is used in patients with haemophilia as a way of assessing the effectiveness of health care, especially as cure is not possible. We report the first such study on patients with chronic coagulation disorders in Australia, using The RAND 36-item Health Survey 1.0 (SF-36), a standardized validated questionnaire combined with a semistructured interview. The mean scores for the eight domains of the SF-36 ranged from 52.5 +/- 42.1 for physical role to 80.0 +/- 20.0 for social functioning. Comparison with normative data obtained from the Australian Bureau of Statistics (ABS) demonstrated a reduction in all domains in this population with statistically significant reductions in general health, physical role limitation and vitality. Comparison with other studies indicates that the HR-QoL of patients with haemophilia and von Willebrand's disorder in Australia is comparable with other Western countries, reflecting the overall similar quality of care available to these patients. This study also provides a good cross-sectional view of the psychosocial factors of life in patients in Australia and recognizes the positive family support available to this population, while raising relevant shortcomings in schools and at the workplace that need to be studied further in a controlled manner.

Adolescent↗
PubMed2001

Vaccination status of children living in rural areas in the United States: are they protected?

OBJECTIVE: To estimate the vaccination coverage levels of children living in rural areas and identify statistically significant differences in coverage between children living in rural areas and their suburban and urban counterparts. METHODS: Children aged 19 to 35 months participating in the 1999 National Immunization Survey (NIS) were included in the study. Children were classified as living in a rural, urban, or suburban area based on their telephone exchange (area code plus the first three digits of the telephone number). Statistically significant differences in vaccination coverage levels between the rural population and their urban counterparts were determined for individual vaccines and vaccine series. RESULTS: Overall, 18% of the children included in the 1999 NIS lived in a rural area, 46% lived in a suburban area, and 36% lived in an urban area. The characteristics of the rural population were: 72% were white, non-Hispanic; 24% were below the poverty level; 16% had a mother with <12 years of education; and 30% received vaccinations from a public provider. Eighty percent of rural children, 79% of suburban children, and 77% of urban children completed the 4:3:1:3 series. The rural population had statistically significantly lower (p<0.01) varicella coverage levels than their suburban and urban counterparts. CONCLUSION: Results of this study suggest that children living in rural areas are just as likely to receive the basic 4:3:1:3 vaccination series as their suburban and urban counterparts. Uptake of the varicella vaccine appears to be slower in rural areas than urban areas. Further studies are recommended to identify the risk factors for not receiving the varicella vaccine in rural areas.

Chickenpox Vaccine↗