[Study of reciprocal action in microorganisms of a population by statistical methods].
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Bacteria↗
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[Suicide in Denmark over 70 years, 1922-1991. General tendencies].
The frequency of suicide in Denmark has been studied for a period of 70 years. Rates of suicide per 100,000 inhabitants, 15 years and over, by age and sex have been calculated, the calculation being based on data from the Danish Cause-of-Death statistics and from the Population statistics provided by Danmarks Statistik. Although the frequency of suicide has varied during the period under study, the overall trend has been one of significant increase. The increase is in great part due to the fact that an increasing number of women, especially women in their 50s, commit suicide. The increase in male rates is more evenly distributed over all age groups and, contrary to what is the case for women, the age-effect is still strong for men.
Adolescent↗
Introduction to statistical analysis of population data in immunogenetics.
We review the most classical questions addressed by the analysis of population data in immunogenetics. Basic genetics' definitions are reminded. Questions related to the population data itself (structure, missing values nomenclature, sampling) are developed first, and secondly, the population genetics questions (relevance of genetic parameters (phenotype, genotype allele and haplotype frequencies; genetic distances; linkage disequilibrium measures), methods and practical computing) are illustrated by immunogenetics polymorphisms. This article gives the essential of population immunogenetics on examples and key references. We underline the importance of population dimension in statistical analysis: structure of linkage disequilibrium and genetic diversity between populations may affect the power of the study or the interpretation of correlations between markers, genes and diseases, making population genetics both theoretical and very practical.
Data Interpretation, Statistical↗
Exponential distance statistics to detect the effects of population subdivision.
Statistical tests are needed to determine whether spatial structure has had a significant effect on the genetic differentiation of subpopulations. Here we introduce a new family of statistics based on a sum of an exponential function of the distances between individuals, which can be used with any genetic distance (e.g., nucleotide differences, number of nonshared alleles, or separation on a phylogenetic tree). The power of the tests to detect genetic differentiation in Wright-Fisher island models and stepping stone models was calculated for various sample sizes, rates of migration and mutation, and definitions of spatial neighborhoods. We found that our new test was in some cases more powerful than the Ks* statistic of Hudson et al. (Mol. Biol. Evol. 9, 138-151, 1992), but in all cases was slightly less powerful than both a traditional chi2 test without lumping of rare haplotypes and the S(nn) test of Hudson (Genetics 155, 2011-2014, 2000). However, when we applied our new tests to three data sets, we found in some cases highly significant results that were missed by the other tests.
Animals↗
Increasing mortality from amyotrophic lateral sclerosis in Norway?
OBJECTIVE: To investigate a possible increase in incidence of ALS in Norway. METHODS: Death certificate data from all deaths in Norway in the period 1961 to 1994 for ALS, PD, and MG were obtained from Statistics Norway and related to population statistics. Data on ALS was obtained on sex, age, and place of death and compared with mortality data in PD and MG for the same period. Data were standardized using the 1990 population as standard population. Poisson regression was used to test for trends in mortality. The data from the death certificates were related to a clinical study performed on ALS in one of the counties during the same period. RESULTS: The annual mortality of ALS almost doubled during the period studied, rising from 1.38 to 2.54 per 100,000 inhabitants at the end of the study. The increased mortality appeared solely in the population older than 60 years of age, with a peak in mortality in the age group 80 to 84 years. The increase was larger in women than in men, and the ratio between the sexes was 1.32 (men-women, age-adjusted at the end of the study). The mortality in patients with PD showed a similar increase to that seen in ALS, whereas no increase in mortality was observed in patients with a diagnosis of MG. There were considerable differences in ALS mortality in different counties, but no clear regional trends were observed. CONCLUSION: The authors report increasing ALS mortality. Although the increase in mortality is restricted to the population aged 65 years or older, it cannot be explained by increasing age of the general population alone.
Adolescent↗
Predicting 15 year chronic bronchitis mortality in the Whitehall Study.
Fifteen year chronic bronchitis mortality was investigated among 17,717 male civil servants aged 40-64 years participating in the Whitehall Study. Associations were assessed between mortality and Medical Research Council standardised questions about chronic phlegm production and breathlessness, and a measure of lung function. Low FEV1 was the most powerful single predictor of mortality; controlling for age, smoking habits and employment grade, the relative hazards ratio (RHR) was 20. Using mortality rates standardised for age and smoking, the proportion of mortality in the total population statistically attributable to low FEV1 (population excess fraction) was 57%. Breathlessness while walking on the level was the best predictor among the questions and combinations of questions; the relative hazards ratio was 12 and the population excess fraction, 39%. A Medical Research Council definition of chronic bronchitis including chronic phlegm production and breathlessness was also strongly associated with chronic bronchitis mortality (RHR = 13); however, the population excess fraction was only 20%. This definition identified only 30% of the 64 deaths, and added almost nothing to prediction by FEV1 alone. The results suggest that although the combination of chronic phlegm production and chronic airflow limitation is strongly associated with mortality from chronic bronchitis, the presence of chronic phlegm production alone is not associated with mortality.
Adult↗
[Homicide in the elderly. A study of homicide in the aged based on an Aachen autopsy sample of the 10-year period 1976-1985].
Investigations on the peculiarities of homicides of the elderly are missing in the German literature up to the present date. Therefore we undertook an evaluation of the case files collected at the Aachen Institute of Forensic Medicine from the ten-year-period 1976-1985. Among 3736 autopsies we found 183 cases of homicide with 35 victims of 60 years and older. We collected peculiarities of modus operandi related to victim, suspect and offence and compared the data with such from police criminal statistics and partially with German population statistics. Two types of homicide of the elderly can be differentiated: One is independent of the victim's age whereas the other exploits the living conditions in the higher age (living alone, socially isolated, ailing, helpless etc.) For these latter cases the name "Gerontocide" is proposed. The paper deals with the peculiar difficulties of criminal investigation and clarification in such cases, resulting on the one hand from the lack of suspicion if elderly people die, on the other hand from the more difficult detection of causal relationship between offence and death--especially in the presence of severe illness of the victim.
Aged↗
Population and vital statistics, 1981.
"For various reasons some of the data relating to population estimates, vital statistics and causes of death in 1981 were not included in the Statistical Abstract of Israel No. 33, 1982. The purpose of this [article] is to complete the missing data and to revise and update some other data." Statistics are included on population by age, sex, marital status, population group, origin, continent of birth, period of immigration, and religion; marriages, divorces, live births, deaths, natural increase, infant deaths, and stillbirths by religion; characteristics of persons marrying and divorcing, including place of residence, religion, age, previous marital status, and year and duration of marriage; live births, deaths, and infant deaths by district, sub-district, and type of locality of residence; deaths by age, sex, and continent of birth; infant deaths by age, sex, and population group; and selected life table values by population group and sex.
Age Distribution↗
Dealing with uncertainty: statistics for an aging population.
"Uncertainty in statistics and demographic projections for aging and other policy purposes comes from four sources: differences in definitions, sampling error, nonsampling error, and scientific uncertainty. Some of these uncertainties can be reduced by proper planning and coordination, but most often decisions have to be made in the face of some remaining uncertainty. Although decision makers have a tendency to ignore uncertainty, doing so does not lead to good policy-making. Techniques for estimating and reporting on uncertainty include sampling theory, assessment of experts' subjective distributions, sensitivity analysis, and multiple independent estimates." The primary geographical focus is on the United States.
Americas↗
Detection of OH radical in laser induced photodissociation of tetrahydrofuran at 193 nm.
On excitation at 193 nm, tetrahydrofuran (THF) generates OH as one of the photodissociation products. The nascent energy state distribution of the OH radical was measured employing laser induced fluorescence technique. It is observed that the OH radical is formed mostly in the ground vibrational level, with low rotational excitation (approximately 3%). The rotational distribution of OH (v"=0,J) is characterized by rotational temperature of 1250+/-140 K. Two spin-orbit states, 2Pi3/2 and 2Pi1/2 of OH are populated statistically. But, there is a preferential population in Lambda doublet levels. For all rotational numbers, the 2Pi+(A') levels are preferred to the 2Pi-(A") levels. The relative translational energy associated with the photoproducts in the OH channel is calculated to be 17.4+/-2.2 kcal mol-1, giving an fT value of approximately 36%, and the remaining 61% of the available energy is distributed in the internal modes of the other photofragment, i.e., C4H7. The observed distribution of the available energy agrees well with a hybrid model of energy partitioning, predicting an exit barrier of approximately 16 kcal mol-1. Based on both ab initio molecular orbital calculations and experimental results, a plausible mechanism for OH formation is proposed. The mechanism involves three steps, the C-O bond cleavage of the ring, H atom migration to the O atom, and the C-OH bond scission, in sequence, to generate OH from the ground electronic state of THF. Besides this high energy reaction channel, other photodissociation channels of THF have been identified by detecting the stable products, using Fourier transform infrared and gas chromatography.
Chromatography, Gas↗
Biased mutations and microsatellite variation.
Mutation bias is one of the forces that may constrain the variation at microsatellite loci. Here, we study the dynamics of population statistics and the genetic distance between two populations under multiple stepwise mutations with linear bias and random drift. Expressions are derived for these statistics as functions of time, as well as at mutation-drift equilibrium. Applying these expressions to published data on humans and chimpanzees, the regression coefficient of mutation bias on allele size was estimated to be at least between -0.0064 and -0.013. The assumption of mutational bias produces larger estimates of divergence times than are obtained in its absence; in particular, the time of split between African and non-African human populations is estimated to be between 183,000 and 222,000 years, assuming one-step mutations and no selection. With multistep mutations, the divergence time is estimated to be lower.
Animals↗
Population and health.
Population and health ecology as subsystems of the health system are of special interest for public health. The population as a financer and beneficiary of health care determines various needs and possibilities of their realization. In order to establish solid socio-medical diagnosis of population, it is the key parameter, which is being realized through population statistics considering the number and distribution of population according to biological, socio-economic and cultural characteristics, as well as through vital and migration statistics. Health ecology as a subsystem represents the interest of public health from the aspect of monitoring of ecology expositions and the state of other contents of ecology and their impact on health. The establishment of sustainable development of human environment represents a philosophy, which is based on inter-generation equality meaning that present generation should give the future generation an environment in which is possible to live healthy life and realise any other progress. Population and health ecology are subsystems within which is necessary to seek needs that have to be met with the aim of improvement of population in terms of health.
Bosnia and Herzegovina↗
Gene polymorphisms of the renin-angiotensin-aldosterone system and the risk of ischemic stroke: a role of the A1166C/AT1 gene variant.
OBJECTIVE: The role of the renin-angiotensin-aldosterone system (RAAS) genes on predisposition to develop stroke, a multifactorial and polygenic cardiovascular trait, is still under investigation. In the present study we characterized the contributory role of RAAS genes in the susceptibility to develop ischemic stroke in humans. METHODS: Allele and genotype frequencies of RAAS genes were characterized in a population of 215 cases (including only atherothrombotic and lacunar forms) and 236 controls selected in Sardinia, a large Mediterranean island with a well-known segregated population. Statistical analysis was performed in the whole population and, based on a significant interaction between angiotensin II receptor (AT1) genotype and hypertension, was also repeated in the hypertensive subgroup. RESULTS: A significant association of the C1166/AT1 gene allelic variant with stroke was found when assuming a dominant model of transmission [unadjusted odds ratio (OR)=1.5, 95% confidence interval (CI) 1.1-2.2, P=0.024]. The strength of the association became more evident in the subgroup of hypertensive individuals (135 cases and 110 controls). In fact, in this cohort the independent OR for the AT1 gene was 2.1, 95% CI 1.2-3.7, P=0.006 in the dominant model and 2.0, 95% CI 1.3-3.2, P=0.002 in the additive model. No other RAAS gene was identified as a contributor to stroke. CONCLUSIONS: Our findings support a predisposing role of an AT1 gene variant in the development of ischemic stroke. In particular, the AT1 gene variant exerted a major impact on ischemic stroke occurrence in the presence of hypertension.
Aged↗
[The use of the age concept in monthly population figures].
"In Dutch population statistics age is usually defined as the year in which a demographic event occurs minus the year of birth. This age concept is referred to as age on 31 December. As a consequence of determining age in this manner, interpreting age-specific monthly figures is sometimes difficult.... Statistics Netherlands prefers the concept of age on 31 December for two reasons: it facilitates the linking of cohort and period data in the case of annual figures; using one concept for annual and monthly figures avoids consistency problems." (SUMMARY IN ENG)
Age Distribution↗
Disclusion time measurement studies: a comparison of disclusion time between chronic myofascial pain dysfunction patients and nonpatients: a population analysis.
From a pool of 89 patients, 49 patients were classified as having chronic myofascial pain dysfunction syndrome (MPDS), and 40 were classified as asymptomatic or non-MPDS patients designated as the control group for the study. To achieve balanced sample size in both groups, 40 patients were arbitrarily selected from the MPDS group. All patients from each of the two primary groups were then categorized and assigned to one or more subgroups according to the following criteria: (1) jaw classification, (2) open occlusion, (3) previous orthodontic therapy, or (4) no previous orthodontic therapy. A fifth subgroup composed of only MPDS patients and equally divided into those who had or had not experienced orthodontic therapy was established to determine whether mean disclusion time differences occur between orthodontic and nonorthodontic MPDS patients. All 80 patients were evaluated for disclusion time of their right and left mandibular excursions to determine statistical population comparisons. Statistical assessment of right and left disclusion times for women and men in the MPDS and non-MPDS groups was performed separately for each of the five subgroups. Analysis of the comparisons revealed that in all except two of the subgroups, mean disclusion time was significantly longer in the MPDS patient group than in the non-MPDS group. The two subgroups in which this was not apparent were those with open occlusion and orthodontic patients compared with nonorthodontic patients. These findings suggest that lengthy posterior disclusion time may be of diagnostic importance when the differing etiologic factors of chronic MPDS patients are evaluated.
Adolescent↗
Is there an association between pleural plaques and lung cancer without asbestosis?
OBJECTIVES: A recent review or meta-analysis of epidemiologic studies concluded that persons with asbestos-related pleural plaques do not have an increased risk of lung cancer in the absence of parenchymal asbestosis. The reviewer inferred that this conclusion provided indirect supportive evidence for the proposition that asbestosis is a necessary precursor of asbestos-related lung cancer. The objective of the present communication is to contest these claims. METHODS: Finnish epidemiologic data and population statistics were used to estimate the apparent risk ratio of lung cancer associated with radiographic signs of pleural plaques. Power calculations were applied to compute the needed population sizes to demonstrate that the association is statistically significant. RESULTS: Unrealistically large population studies would be needed to observe the statistical relation between pleural plaques and lung cancer, quantitated as a risk ratio of 1.1, resulting from relatively low levels of environmental asbestos exposure. In realistic and valid epidemiologic studies on heavily exposed subpopulations, a two- or threefold risk can be identified. CONCLUSIONS: Uninformative studies should not be interpreted as providing suppressive evidence that pleural plaques are a noncausal risk indicator of lung cancer. Even for the null hypothesis, the inference that asbestosis is a necessary causal link between asbestos and lung cancer is illogical.
Adult↗
Development and reproducibility of a brief food frequency questionnaire for assessing the fat, fiber, and fruit and vegetable intakes of rural adolescents.
OBJECTIVE: To describe the systematic development and reproducibility of a food frequency questionnaire (FFQ) designed to meet the specific research requirements of the Goals for Health cancer prevention intervention program for rural middle school children. DESIGN: A 4-step process was used to develop a brief FFQ for scoring intakes of total fat, fiber, and fruits and vegetables. The resulting questionnaire consisted of 25 food frequency items and 10 supplemental questions. Reproducibility of the questionnaire was determined by comparing responses at the beginning and end of a 4-month interval. SUBJECTS: Study subjects were sixth- and seventh-grade students attending middle schools in rural areas of Virginia and upstate New York. Seventh-grade students participated in the pilot study, and sixth-grade students participated in the reproducibility study. The final version of the FFQ was completed twice by 539 sixth graders. After exclusions for missing and unreliable data, the usable sample size was 415. Boys were somewhat more likely than girls to be excluded for missing data. African-American students comprised 32% of the population. STATISTICAL ANALYSES PERFORMED: Each food frequency item was associated with 3 scores--a fat score, a fiber score, and a combined score for the number of servings of fruits and vegetables. Means and standard deviations were determined for nutrient variables, differences between repeat administrations were tested for significance by paired t test, and Pearson correlation coefficients were calculated for nutrients and for individual food items. RESULTS: Correlation coefficients for nutrient scores were 0.58 for fat, 0.49 for fiber, and 0.51 for fruits and vegetables. For individual food items, correlations ranged from 0.24 to 0.59 (mean=0.41). APPLICATIONS/CONCLUSIONS: Using a systematic approach to developing a study-specific FFQ for rural adolescents is feasible. Further, the reproducibility of the Goals for Health questionnaire was demonstrated for the 3 nutrient scores it was designed to measure. This developmental approach may be readily adapted to other populations, study designs, and nutrients of interest. The validity of the questionnaire remains to be tested.
Adolescent↗
Data dissemination for the population census.
"Recent developments in the data-dissemination system for census of population statistics are reviewed, with particular reference to Great Britain. Key issues discussed include: the expansion of census output and the need for summaries of census results; the significance of consultation with census users; the development and functions of guides for census users; the emergence of data-dissemination centres and archives offering new services; the functions of area typologies as a new type of census by-product; the demand for Public Use Samples and the problem of confidentiality; and the emergence of large-scale surveys as alternatives to the census."
Censuses↗