Males predominate at the top in chess, and chess is a useful domain to investigate possible causes of gender differences in high achievement. Opportunity, interest and extent of practice can be controlled for. Organized chess has objective performance measures, extensive longitudinal population-level data and little gatekeeper influence. Previous studies of gender differences in chess performance have not controlled adequately for females on average playing fewer rated games and dropping out at higher rates. The present study did so by examining performance of international chess players at asymptote and over equal numbers of rated games. Males still were very disproportionately represented at the top. Top female players showed signs of having less natural talent for chess than top males, such as taking more rated games to gain the grandmaster title. The hypothesis that males predominate because many more males play chess was tested by comparing gender performance differences in nations with varying percentages of female players. In well-practised participants, gender performance differences stayed constant even when the average national percentage of female international players increased from 4.2% to 32.3%. In Georgia, where women are encouraged strongly to play chess and females constitute nearly 32% of international players, gender performance differences are still sizeable. Males on average may have some innate advantages in developing and exercising chess skill.

As a leading indicator of child health, under-five mortality was incorporated in the United Nations Millennium Development Goals with the aim of reducing the rate by two-thirds between 1990 and 2015. Under-five mortality in Nigeria is alarmingly high, and many of the diseases that result in mortality are vaccine preventable. This study evaluates the uptake of childhood immunization in Nigeria from 1990 to 2008. A multi-year trend analysis was carried out using Alternating Logistic Regression on 46,130 children nested within 17,380 mothers in 1938 communities from the Nigerian Demographic and Health Surveys from 1990 to 2008. The findings reveal that mother-level and community-level variability are significantly associated with immunization uptake in Nigeria. The model also indicates that children delivered at private hospitals have a higher chance of being immunized than children who are delivered at home. Children from the poorest families (who are more likely to be delivered at home) have a lower chance of being immunized than those from the richest families (OR=0.712; 95% CI, 0.641–0.792). Similarly, the chance of children with a mother with no education being immunized is decreased by 17% compared with children whose mother has at least a primary education. In the same way, children of mothers who are gainfully employed and those of older mothers have statistically significantly higher odds of being immunized. Children of households with a female head are less likely to be immunized than those from male-headed households. The statistical significance of the community–survey year interaction term suggests an increase in the odds of a child being immunized over the years and spread over communities. Evidence-based policy should lay more emphasis on mother- and community-level risk factors in order to increase immunization coverage among Nigerian children.

This study explores the perceived socio-cultural factors that might be barriers to health-promoting behaviour in middle-aged women in the city of Yazd in Iran. The aim of this qualitative study was to explore the barriers to a healthy lifestyle in middle-aged women. Interviews with women aged 40–60 were audio-taped, transcribed and analysed using content analysis. The interviews focused on socio-cultural factors and five main themes emerged: (a) giving higher priority to non-health-related needs; (b) the dominance of the husband's will in the family; (c) preference of children's needs to own needs; (d) having to fulfil multiple responsibilities; and (e) low access to community resources for health promotion. The multiple responsibilities of family and work, patriarchal societal attitudes and lack of exercise facilities are barriers to health in middle-aged Iranian women.

The population of Robinson Crusoe Island is estimated at 633 inhabitants. The current population has a common origin from the first eight families who colonized the island at the end of the 19th century. The objective of this study was to determine the rates of consanguinity, the average coefficients of inbreeding, the types of consanguineous marriages and the inbreeding evolution between 1900 and 2000 on the island. All marriages registered on the island, from the last colonization until 2000 (417 in total), were included in the analysis. In addition, extended genealogies were obtained. The consanguinity rate was 14.9% and the average coefficient of inbreeding (α) 54.05×10–4. The most frequent type of consanguineous marriages was between second cousins, followed by first cousins. The average value of the first/second cousin ratio was 1.11. The population of Robinson Crusoe Island has a high rate of inbreeding. The unique characteristic of the island – its small current population, originating from just a few families, with small rate of gene flow – could explain the observed high and increasing consanguinity.

Mass media play an important role in changing body image. This study aimed to determine the role of media (magazines and television) in body weight concern among university females in five Arab countries. A total sample of 1134 female university students was selected at convenience from universities in five Arab countries: Bahrain, Egypt, Jordan, Oman and Syria. The females' ages ranged from 17 to 32. A pre-tested questionnaire was used to assess the exposure to mass media regarding weight concerns. For the variables on exposure to mass media, girls were divided into two groups: infrequently exposed and frequently exposed. In general, the females who were exposed to mass media had a greater risk of having dieted to lose weight and changing their ideas of a perfect body shape than those who were not exposed or infrequently exposed. The association of exposure to magazines with having dieted to lose weight was only significant among females in Bahrain (p<0.044), Egypt (p<0.001) and Jordan (p<0.001). Exposure to television had a weaker association than exposure to magazines with body weight concerns of females. The association of exposure to television with females' idea of a perfect body shape was only statistically significant in females in Egypt (p<0.019) and Oman (p<0.019). The pressure from mass media on the body weight concern of female university students may lead these women to practise unhealthy weight control diets.

Short sleep duration is associated with obesity in young children. This study develops the hypothesis that parental rules play a role in this association. Participants were 3-year-old children and their parents, recruited at nursery schools in socioeconomically deprived and non-deprived areas of a North-East England town. Parents were interviewed to assess their use of sleep, television-viewing and dietary rules, and given diaries to document their child's sleep for 4 days/5 nights. Children were measured for height, weight, waist circumference and triceps and subscapular skinfold thicknesses. One-hundred and eight families participated (84 with complete sleep data and 96 with complete body composition data). Parental rules were significantly associated together, were associated with longer night-time sleep and were more prevalent in the non-deprived-area compared with the deprived-area group. Television-viewing and dietary rules were associated with leaner body composition. Parental rules may in part confound the association between night-time sleep duration and obesity in young children, as rules cluster together across behavioural domains and are associated with both sleep duration and body composition. This hypothesis should be tested rigorously in large representative samples.

Height is regarded as one of the indicators of environmental stress at population level, being an excellent barometer of standard of living. The aim of this study was to describe diversity in height among populations living in different regions of the Kingdom of Poland in terms of the economic factors in the second half of the 19th and early 20th century. This study examines the height of adult inhabitants from five guberniyas (provinces) of the Kingdom of Poland (Łomża, Warsaw, Radom, Kalisz and Płock) collected in the years 1897–1914 (N=732 men, N=569 women). Differences in average height of male and female inhabitants across the five guberniyas were examined using ANOVA and the Fisher's LSD (Least Significant Difference) test of multiple comparisons. Statistically significant differences in the height between the guberniyas were observed. Diversity in the economic development in the studied guberniyas of the Kingdom of Poland translated into differences in the height of their inhabitants. Moreover, an increase in mean height over time was noted.

Using data from The National Epidemiologic Survey on Alcohol and Related Conditions, the strength of social networks and the association of self-reported health among American Indians and Alaska Natives (AI/AN) and non-Hispanic Whites (NHW) were compared. Differences in social network–health relationships between AI/ANs and NHWs were also examined. For both groups, those with fewer network members were more likely to report fair or poor health than those with average or more network members, and persons with the fewest types of relationships had worse self-reported health than those with the average or very diverse types of relationships. Furthermore, small social networks were associated with much worse self-reported health in AI/ANs than in NHWs.

There is now fairly substantial evidence of a socioeconomic gradient in low birth weight for developed countries. The standard summary statistic for this gradient is the concentration index. Using data from the recently published Growing Up in Ireland survey, this paper calculates this index for low birth weight arising from preterm and intrauterine growth retardation. It also carries out a decomposition of this index for the different sources of low birth weight and finds that income inequality appears to be less important for the case of preterm births, while father's education and local environmental conditions appear to be more relevant for intrauterine growth retardation. The application of the standard Blinder–Oaxaca decomposition also indicates that the socioeconomic gradient for low birth weight appears to arise owing to different characteristics between rich and poor, and not because the impact of any given characteristic on low birth weight differs between rich and poor.

Information on the current prevalence and types of consanguineous marriages in Malakand District, Khyber Pakhtunkhwa Province (KPK), Pakistan, was collected from 1192 rural couples. Some 66.4% of marriages were between couples related as second cousins or closer (F≥0.0156), equivalent to a mean coefficient of inbreeding (α) of 0.0338. The data suggest that the prevalence of consanguineous unions in Malakand has been increasing during the last decade, in response to the high levels of violence across KPK.

On 11th March 2011 a magnitude nine earthquake struck the Tohoku region of Japan. The earthquake resulted in a large tsunami and an accident at the Fukushima Nuclear Power Plant. Previous studies have suggested that demographic indices relating to reproduction and marriage change after such massive disasters (e.g. large earthquakes). The present study investigated whether the number of births, number of marriages and the secondary sex ratio (SSR) changed after the East Japan Earthquake. The monthly number of births (males and females, separately) and marriages in each prefecture in Japan from January 1997 to June 2012 were obtained from the Demographic Survey of Japan. An analysis was performed for three different geographic boundary units: the disaster-stricken area, the non-disaster-stricken area and the whole of Japan. In each unit, the numbers of births and marriages in a given month during the post-disaster period were predicted based on a regression equation estimated by the numbers of births and marriages in that month during the pre-disaster period. The numbers of observed monthly births and marriages during the post-disaster period were compared with the predicted figures. Differences between the observed and predicted numbers were determined by referring to the 95% confidence limits for the predicted mean number. The observed probability of a male birth in a given month during the post-disaster period was compared with a 95% confidence interval of a binominal distribution. In all three boundary units, the number of births was significantly lower than the predicted number by about 3–8% from nine months after the disaster, while the number of marriages in October 2011 was significantly lower than the predicted number by about 25–28%. In October 2011, the SSR in the whole of Japan had decreased from 104.8 (the predicted SSR) to 102.9. The number of births and marriages and the SSR decreased in Japan after the East Japan Earthquake irrespective of locality.

This paper assesses women's awareness of the liberalization of abortion law and their knowledge of a place for obtaining abortion services in Nepal. The data are from the 2011 Nepal Demographic and Health Survey. The results are compared with data from a similar survey conducted in 2006. Variations in the two measures among several population sub-groups are analysed by performing logistic regression. Among women aged 15–44, 38.7% (CI: 37.8, 39.6) were aware of the legal status of abortion and 59.8% (CI: 58.9, 60.7) knew of a place to have an abortion. The percentages of both measures varied considerably by various population sub-groups. Over a 5-year period, knowledge of the legality of abortion increased by 6.4 percentage points, and awareness of service delivery sites increased by 3.3 percentage points. The increases in both measures were, however, largely limited to higher wealth quintiles and those with higher educational attainment. The results suggest the need to intensify efforts to educate women in Nepal, particularly the most disadvantaged women, about abortion law, including the conditions under which abortion is permitted, and where to access safe abortion services.