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PubMed1989

Michigan Alcoholism Screening Test (MAST)--its possibilities and shortcomings as a screening device in a pre-selected non-clinical population.

A statistical analysis of the MAST scores obtained by its administration to industrial workers, hospitalized alcoholics and persons arrested driving while intoxicated has been performed. The author discusses the modalities and possibilities of improving the test reliability which will increase its efficiency in the screening of alcohol related disabilities. A further study of the inconsistencies in the administration of the MAST along with its validation is planned.

Adult↗
PubMed2002

Mapping and analysis of quantitative trait loci in experimental populations.

Simple statistical methods for the study of quantitative trait loci (QTL), such as analysis of variance, have given way to methods that involve several markers and high-resolution genetic maps. As a result, the mapping community has been provided with statistical and computational tools that have much greater power than ever before for studying and locating multiple and interacting QTL. Apart from their immediate practical applications, the lessons learnt from this evolution of QTL methodology might also be generally relevant to other types of functional genomics approach that are aimed at the dissection of complex phenotypes, such as microarray assessment of gene expression.

Algorithms↗
PubMed2005

Detection of O(3P(J)) atoms formed by reaction, Al+O2--> AlO+O under crossed-beam condition.

The vacuum ultraviolet laser-induced fluorescence technique was employed to detect the oxygen atoms formed by the reaction, Al+O(2)--> AlO+O. The measurements were carried out under the crossed-beam condition at 12.2 kJmol of collision energy. The relative populations of three spin-orbit states of O((3)P(J)) were determined to be 3.8, 1.0, and 0.2 for J=2, 1, and 0, respectively. They show nonstatistical populations, i.e., more population in O((3)P(2)) and less population in O((3)P(0)) than the statistical expectation. These populations were almost identical for two Al beam conditions where the relative concentrations of two spin-orbit states of Al, (2)P(1/2), and (2)P(3/2), are different. These results suggest that the reaction of Al with O(2) proceeds via an intermediate complex where the memory of the initial spin-orbit state is lost. Deviation from the statistical population of O((3)P(J)) implies the occurrence of the interaction among potential surfaces in the exit channel.

Journal Article↗
PubMed2005

Survey of caffeine levels in retail beverages in Portugal.

The caffeine content of 85 retail beverage samples purchased from local supermarkets between 1995 and 2004 was determined. The potential intake of caffeine through the consumption of these beverages (but excluding coffee) was estimated for students of the University of Coimbra, Portugal. The caffeine content of the beverages ranged from 47.5 to 282.5 mg l(-1) for teas, from 20.1 to 47.2 mg l(-1) for tea extracts samples, and from 80.7 to 168.7 mg l(-1) for cola soft drinks. Caffeine was not completely absent from caffeine-free colas, and energy drinks had a far greater caffeine content than regular drinks, ranging from 21 to 2175 mg l(-1). Soft drinks were consumed by 72% of the individuals, although 14% of the survey participants did not drink any of the different types of the beverages studied. Contrary to expectations for this age group, no consumptions of energy drinks was reported. Daily caffeine intake was estimated to range from 4.7 to 200 mg day(-1), but with only 5% reporting a daily intake around 200 mg caffeine. Cola-type beverages were an important dietary source of caffeine for the population studied. Statistical differences in the caffeine intake between the male and female populations were found, with p = 0.014, being higher for the male population. Of the beverages studied, cola-type drinks showed statistical differences for the male population, p = 0.03, and tea showed statistical differences for female population p = 0.013, respectively.

Adult↗
PubMedDate not supplied

Protecting confidentiality in small population health and environmental statistics.

Public policy decisions are fuelled by information. Often, this information is in the form of statistical data. Questions stemming from public health and environmental concerns often arise or are studied within small subgroups of a population. Continuing improvements in the performance and availability of computing resources, including geographic information systems, and the need to better understand environmental exposures and consequent health effects create increasing demand for small population health and environmental data. These demands are at odds with the need to preserve the privacy and data confidentiality of persons, groups or organizations covered by the data. Although confidentiality issues for demographic and economic data are well-studied and are gaining maturity for health data, these issues are only beginning to emerge for environmental data and combined environmental-health data. The aim of this paper is to provide a framework for that examination. Herein we examine confidentiality problems posed by small population health and environmental data, summarize available statistical methods, and propose avenues for the solution of new problems.

Computer Graphics↗
PubMed1975

[Use of computers in clinical psychiatry. Statistical study of a population of treated alcoholics].

According to their own standardized Patient Data Inventory, the authors proceed to a statistical comparative evaluation of 55 males neurotic or psychosomatic hospitalized alcholics and of two control groups of non-alcoholic neurotic or psychosomatic male patients: 252 ambulatory and 72 hospitalized. The authors find significant differences between alcoholics and non-alcoholics, especially: 1 no.) heavier family history (psychoses, dysgenetic disorders), greater incidence of psychosomatic disorders in the previous history, more distrubed parental relations in childhood (maternal overprotection and lack of paternal authority); 2 no.) from the patient viewpoint: a louder expression of somatic and functionnal complaints; 3 no.) from the therapist viewpoint, less emotionality, weaker expression of aggressiveness (either overt or latent).

Aggression↗
PubMed2004

Multilocus estimation of genetic structure within populations.

Spatial structure of genetic variation within populations is well measured by statistics based on the distribution of pairs of individual genotypes, and various such statistics have been widely used in experimental studies. However, the problem of uncharacterized correlations among statistics for different alleles has limited the applications of multiallelic, multilocus summary measures, since these had unknown sampling distributions. Usually multiple alleles and/or multiple loci are required in order to precisely measure spatial structures, and to provide precise indirect estimates of the amount of dispersal in samples of reasonable size. This article examines the correlations among pair-wise statistics, including Moran I-statistics and various measures of conditional kinship, for different alleles of a locus. First the correlations are mathematically derived for random spatial distributions, which allow averages over alleles and loci to be used as more powerful yet exact test statistics for the null hypothesis. Then extensive computer simulations are conducted to examine the correlations among values for different alleles under isolation by distance processes. For loci with more than three alleles, the results show that the correlations are remarkably and perhaps surprisingly small, establishing the principle that then alleles behave as nearly independent realizations of space-time stochastic processes. The results also show that the correlations are largely robust with respect to the degree of spatial structure, and they can be used in a straightforward manner to form confidence intervals for averages. The results allow a precise connection between observations in experimental studies and levels of dispersal in theoretical models.

Alleles↗
PubMed2002

Spatial coding of position and orientation in primary visual cortex.

We examined the spatial distribution of population activity in primary visual cortex (V1) of tree shrews with optical imaging and electrophysiology. A line stimulus, thinner than the average V1 receptive field, evoked a broad strip of neural activity of nearly constant size for all stimulus locations tested within the central 10 degrees of visual space. Stimuli in adjacent positions activated highly overlapping populations of neurons; nevertheless, small changes in stimulus position produced orderly changes in the location of the peak of the population response. Statistically significant shifts in the population response were found for stimulus displacements an order of magnitude smaller than receptive field width, down to the limit of optical imaging resolution. Based on the pattern of population activity, we conclude that the map of visual space in V1 is orderly at a fine scale and has uniform coverage of position and orientation without local relationships in the mapping of these features.

Action Potentials↗
PubMed2000

Microsatellite size homoplasy, SSCP, and population structure: a case study in the freshwater snail Bulinus truncatus.

The extent of microsatellite size homoplasy, as well as its effect on several population genetics statistics, was investigated in natural populations using the single-strand conformation polymorphism (SSCP) method. The analysis was conducted using 240 individuals from 13 populations of the freshwater snail Bulinus truncatus at a GT(n)CT(m) compound microsatellite locus. We showed that SSCP can be used to uncover, at least partly, size homoplasy in the core sequence of this category of loci. Eight conformers (SSCP variants) were detected among the three size variants (electromorphs). Sequencing revealed that each conformer corresponded to a different combination of repeats in the GT(n) and CT(m) arrays. Part of this additional variability was detected within populations, resulting in a substantial increase in gene diversity in four populations. Additional variability also changed the values of parameters used to analyze population differentiation among populations: pairwise tests of differentiation were significant much more often with conformers than with electromorphs. On the other hand, pairwise estimates of F(st) were either smaller or larger with conformers than with electromorphs, depending on whether or not electromorphs were shared among populations. However, estimates of F(st) (or analogs) over all populations were very similar, ranging between 0.66 and 0.75. Our results were consistent with the theoretical prediction that homoplasy should not always lead to stronger population structure. Finally, conformer sequences and electromorph size distribution suggested that single-point and/or stepwise mutations occurring simultaneously in the different repeated arrays of compound microsatellites produce sequence variation without size variation and hence generate more size homoplasy than expected under a simple stepwise mutation model.

Animals↗