The political consequences of Welsh identity*

The 1991 British Census was the first to ask a question on ethnic group. This Research note provides a brief review of the development of the question and then uses the Samples of Anonymised Records, also newly available in 1991, to explore the construction of the ten ethnic groups derived by the Census Offices; the family and household composition of the ten groups and the implications of this construction for the analysis of ethnic differences.     

Triiodothyronine influences quail myoblast proliferation and differentiation*

The influence of triiodothyronine (T3) on avian myoblast proliferation and differentiation was studied in secondary cultures using plating densities of 2500 and 7000 cells/cm². Culture media were depleted of T3 (control myoblasts) and increasing amounts were then added to concentrations of 0.6, 3 and 15 nM T3 (treated myoblasts). Independent of the cell density, T3 induced a dose-related decrease in myoblast proliferation measured by cell number, doubling time and ³H-thymidine incorporation. However, with the lower plating density, this influence was delayed, occurring only after the third day of culture for 0.6 nM T3-treated myoblasts and simultaneous with the onset of myosin heavy chain accumulation. Moreover, when myoblasts were exposed to BrdU for 48 h, the T3 growth inhibitory effect disappeared, thus showing that this effect was clearly linked to differentiation. In addition, we have shown that T3 induced an early fusion of myoblasts: 65% of the maximal value of the fusion index was reached on day 3 in the T3-treated cells in comparison to 25% in the control myoblasts. This hormone also enhanced accumulation of muscle-specific proteins (connectin, acetylcholine receptors, myosin heavy chain), tested by cytoimmunofluorescence, ELISA, binding experiments and Western blot. All these results show that T3 increased myoblast differentiation through a pathway including myoblast withdrawal from the cell cycle. The influence of T3 could partly explain its previously reported positive effect on the number of muscle fibers.     

Genetic differentiation and biochemical polymorphism among trichomonads

Isoenzyme electrophoresis was used to study levels of genetic differentiation among strains and clones of Trichomonas gallinae, Trichomonas vaginalis, Tritrichomonas foetus, Tetratrichomonas gallinarum, and Pentatrichomonas hominis. Strain variation was found within T. gallinae, T. vaginalis, and T. foetus, however, levels of enzyme polymorphism were greater in T. gallinae than in T. vaginalis or T. foetus. Isoenzyme genotypes were not a stable property of T. gallinae clones cultivated in vitro. Retrospective studies of T. gallinae SG and JB6 clones revealed that mutation occurred during in vitro cultivation. Heterozygotes of hexokinase-1 and phosphoglucomutase displayed 2 allomorphs in equal dosage, indicating that trichomonads are diploid for these protein loci. Phenetic clustering of the biochemical data suggests that levels of genetic divergence among the species studied are extensive.     

Childlessness among American women

Abstract

The rate of childlessness in the United States has increased over the last two decades. Changing or differential rates by different segments of society have important implications for society. Most previous studies have relied on unrepresentative opportunistic samples to identify those segments of society with lower or higher rates of childlessness. These types of samples may misestimate both the number of women planning to remain childless and the magnitude of the correlates of childlessness. The present study uses these previous studies to identify predictor variables, but tests their significance using a recent national representative sample of women in the United States, aged 20–44: Cycle III of the National Survey for Family Growth, collected in 1982. The most important demographic factors are marital status and fecundity status, followed by age, race or ethnicity, education of the respondent, labor force status, and region. Father's education and mother's education are slightly, but not significantly, related to childlessness. Contrary to findings from less representative samples, urban‐rural differences and religion are not related to childlessness.     

Genetic differentiation among Sardinian villages.

The present study reports an analysis of genetic differentiation among 14 Sardinian villages located mainly in the center of the island. Chi-square tests show significant genetic heterogeneity among villages, and analyses by F- and R- statistics indicate an essentially random pattern of differentiation for all alleles. Using the kinship methods of Morton, a matrix, R, with elements rij describing the correlations between the gene frequencies of villages i and j is obtained. Use of Malécot's formula relating the rij to the geographic distances between villages shows a rapid decline of kinship with increasing distance but reveals essentially no relationship for distances over 40 km. Rotation of a two-dimensional reduction of the kinship matrix to maximum congruence with the geographic distances indicates that about 25% of the genetic distances can be accounted for by the geographic location of the villages. Isolation due in part to cultural factors, genetic drift, and special local or regional patterns of villages associations appear to be involved in the pattern of genetic variation.     

Voluntary sterilisation among Canadian women

Using data from the 1984 Canadian Fertility Survey, proportional hazards modelling was employed to determine factors associated with the likelihood of voluntary sterilisation among 5315 women of childbearing age, and the trends in timing and differences in the likelihood associated with different age cohorts. Multivariate analysis suggests that educational attainment, parity and duration since last birth at the time of sterilisation, religious commitment, province of residence and marital status at the time of sterilisation, are all important predictors. Education and parity attainment emerged as the best predictors of the timing of voluntary sterilisation in all age cohorts, but the contribution of other covariates varies between cohorts.     

Abortion-seeking behaviour among Nigerian women

This study used data from a community-based survey to examine women's experiences of abortion in Nigeria. Fourteen percent of respondents reported that they had ever tried to terminate a pregnancy, and 10% had obtained an abortion. The majority of women who sought an abortion did so early in the pregnancy. Forty-two percent of women who obtained an abortion used the services of a non-professional provider, a quarter experienced complications and 9% sought treatment for complications from their abortions. Roughly half of the women who obtained an abortion used a method other than D&C or MVA. The abortion prevalence and conditions under which women sought abortions varied by women's socio-demographic characteristics. Because abortion is illegal in Nigeria except to save the woman's life, many women take significant risks to terminate unwanted pregnancies. Reducing the incidence of unwanted pregnancy and unsafe abortion can significantly impact the reproductive health of women in Nigeria.     

Drought and economic differentiation among Ariaal pastoralists of Kenya

This paper examines the effects of the 1984 drought upon household wealth differences in a community of Ariaal pastoralists of northern Kenya. The database consists of 1985 post-drought livestock counts and informants' statements of species-specific drought loss, compared to 1976 livestock counts on the same 38 households. The analysis confirms the hypothesis that the drought resulted in increased household wealth inequalities. It is suggested that the combination of differential herd growth, differential participation in the cash market, and differential loss to the drought has contributed to a polarization within Ariaal of rich and poor, resulting in rural proletarianization and urban migration.     

Patterns of differentiation among endangered pondberry populations

Pondberry, Lindera melissifolia, is an endangered and partially clonally reproducing shrub species found in isolated populations that inhabit seasonally wet depressions in forested areas of the lower Mississippi River alluvial valley and southeastern regions of the United States. With eleven microsatellite loci, we quantified population genetic differentiation and diversity among 450 genets in 10 locations distributed across pondberry’s range. We used estimates of F _st and Jost’s D _est to measure genetic differences between populations and between geographic regions. The largest pairwise regional difference was found between eastern and western regional population groups (F _st = 0.23, D _est = 0.67), with the northern-most population groups in each region exhibiting larger divergence from each other than the southern-most population groups. Genetic diversity was lowest in the Sand Pond Conservation Area (A _e = 1.9, H _e = 0.36), which was the northern-most pondberry population, and highest in the Francis Marion National Forest (A _e = 4.1, H _e = 0.69), although we identified only 17 genets in that admixed population. Following adjustments for estimated null allele frequencies, we identified heterozygote excess in four eastern populations and found no evidence for inbreeding in any population. The observed patterns of differentiation indicate a phylogeography that exhibits an Appalachian Mountain discontinuity coupled with northward migrations along the Southern Atlantic Coastal Plain and into the Mississippi Alluvial Plain. The genetic consequences of this proposed phylogeographical structure may affect selection of germplasm sources for population reestablishment programs across pondberry’s range.     

Genetic differentiation among Iranian Christian communities.

From some 500 members of Christian communities in Iran (Armenians and Assyrians from six localities), blood specimens were obtained and examined for a number of blood group, red cell enzyme, and serum protein systems. The results indicate the relatively closed nature of the Christian community as a whole but that moderate differentiation has already occurred among the local groups. One factor in this diversification process that can be distinguished is the effect of urbanization in Tehran, but otherwise it seems to be largely random.     

Smoking and health care patterns among pregnant women

A population-based hospital survey of 3628 women in the postpartum period was conducted in the Ottawa-Carleton region in 1983 to determine the prevalence of smoking before and during pregnancy, the demographic and socioeconomic characteristics of women who smoke during pregnancy and the use of health care services by these women. Of the 3628 women 91% completed a full-length questionnaire and 4% completed a shorter questionnaire. Before pregnancy 37.4% of the women smoked cigarettes. Overall, 61.1% of the smokers changed their smoking habit: 31.1% stopped, 28.1% decreased the amount smoked and 2.0% increased the amount smoked. Two thirds of the women who stopped smoking did so as soon as they realized they were pregnant. Over 50% of teenagers, single women, women living common-law and women with less than a grade 11 education smoked after the 3rd month of pregnancy. The physician is in an ideal position to identify as soon as possible pregnant women who smoke and to initiate a health education program. Only a few women who smoked during pregnancy attended early prenatal classes. Physicians and class organizers must work to improve this situation if such classes are to have an impact on smoking during pregnancy.     

Genetic differentiation among populations of marine algae

Most of the information for genetic differentiation among populations of marine algae is from studies on ecotypic variation. Physiological ecotypes have been described for individuals showing different responses to temperature and salinity conditions. Morphological ecotypes have also been found associated with areas differing in wave exposure or different intertidal positions. Little is known on how genetic variation is organized within and between populations of marine algae. The occurrence of ecotypic variation in some species is evidence for genetic differentiation among populations resulting from selection by the local environment. The rate of dispersal and subsequent gene flow will also affect the level of differentiation among populations. In species with low dispersal, differentiation can arise through chance founder events or random genetic drift. The few studies available have shown that species of algae exhibit a range of dispersal capabilities. This information can be useful for predicting the potential level of genetic differentiation among populations of these species. Crossing experiments with several species of algae have shown that populations separated by a considerable distance can be interfertile. In some cases individuals from these populations have been found to be morphologically distinct. Crosses have been used to study the genetic basis of this variation and are evidence for genetic differentiation among the populations sampled. Genetic variation of enzyme proteins detected by electrophoresis provides an additional method for measuring genetic variation within and between populations of marine algae. Electrophoretic methods have previously been used to study systematic problems in algae. However, there have been few attempts to use electrophoretic variation to study the genetic structure of populations of marine algae. This approach is outlined and includes some of the potential problems associated with interpreting electrophoretic data. Studies of electrophoretic variation in natural populations ofEnteromorpha linza from Long island Sound are used as an example. This species was found to reproduce only asexually. Despite a dispersing spore stage, genetic differentiation was found on a microgeographic scale and was correlated with differences in the local environment of some of the populations. Similar studies on other species, and especially sexually reproducing species, will add to a growing understanding of the evolutionary genetics of marine algae.Paper presented at the Seaweed Biogeography Workshop of the International Working Group on Seaweed Biogeography, held from 3–7 April 1984 at the Department of Marine Biology, Rijksuniversiteit Groningen (The Netherlands). Convenor: C. van den Hoek.     

GST among issues raised during CMA workshop on political lobbying

A recent CMA-sponsored workshop on political lobbying attracted many more physicians than anticipated. Dr. Bill Acker, chair of the Political Action Committee, said this is a sign of physicians'' growing interest in lobbying and politics.     

Induced abortion potential among Indian women

Information on abortion is limited and inaccurate, especially in the developing world, which has led to speculation on the prevalence of abortion in these regions. A rise in prevalence of abortion is mostly counted in terms of increase in the prevalence of induced abortions which reflects on the reproductive health of women. With the growing concern for the reproductive health of women, the study of abortion has drawn the attention of researchers world-wide. This paper is an attempt to assess the induced abortion potential among Indian women by utilizing information on proportion of unwanted and ill-timed pregnancies obtained through National Family Health Survey, India. This exercise may facilitate a better understanding of the exact prevalence of induced abortion, which necessarily should be less than the estimated potential depending on the levels of unwanted and ill-timed fertility.