Near Extremal Kerr Entropy from AdS_2 Quantum Gravity

We analyze the asymptotic symmetries of near extremal Kerr black holes in four dimensions using the AdS_2/CFT_1 correspondence. We find a Virasoro algebra with central charge c_R=12J that is independent from the Virasoro algebra (with the same central charge) that acts on the degenerate ground state. The energy of the excitations is computed as well, and we can use Cardy's formula to determine the near extremal entropy. Our result is consistent with the Bekenstein-Hawking area law for near extremal Kerr black holes.Comment: 28 pages. v2: references added, typos correcte

School performance of international adoptees better than expected from cognitive test results

Objective: To investigate school performance of international adoptees in relation to their cognitive competence. Method: From the population of all male Swedish residents born 1973–1976, registered in the census 1985 and with complete test scores from military conscription, the following study groups were identified: Korean adoptees (n = 320), non-Korean adoptees (n = 1,125), siblings (children born by adoptive parents, n = 190) and Swedish majority comparisons (n = 142,024). Global scores from intelligence tests at conscription were compared with grade points from the last compulsory school year (year 9). Linear and logistic regression was applied in statistical analyses. Results: The mean grade points in theoretical subjects were lower in non-Korean adoptees than in the majority population, but when global test scores from military conscription were adjusted for, outcomes were significantly better, equal for physics, than in the majority population. The grade points of Korean adoptees were higher than in the majority population and the same held true after adjusting for global test scores. When SES was taken into account, the risk of poor school performance (only completed lower subject levels) increased in non-Korean adoptees compared to models only adjusted for age and sex. Conclusion: Male international adoptees generally perform better in school than expected by their cognitive competence. A cognitive evaluation is important in the assessment of adoptees with learning difficulties

Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis

<p><b>Background:</b> Grip strength, walking speed, chair rising and standing balance time are objective measures of physical capability that characterise current health and predict survival in older populations. Socioeconomic position (SEP) in childhood may influence the peak level of physical capability achieved in early adulthood, thereby affecting levels in later adulthood. We have undertaken a systematic review with meta-analyses to test the hypothesis that adverse childhood SEP is associated with lower levels of objectively measured physical capability in adulthood.</p> <p><b>Methods and Findings:</b> Relevant studies published by May 2010 were identified through literature searches using EMBASE and MEDLINE. Unpublished results were obtained from study investigators. Results were provided by all study investigators in a standard format and pooled using random-effects meta-analyses. 19 studies were included in the review. Total sample sizes in meta-analyses ranged from N = 17,215 for chair rise time to N = 1,061,855 for grip strength. Although heterogeneity was detected, there was consistent evidence in age adjusted models that lower childhood SEP was associated with modest reductions in physical capability levels in adulthood: comparing the lowest with the highest childhood SEP there was a reduction in grip strength of 0.13 standard deviations (95% CI: 0.06, 0.21), a reduction in mean walking speed of 0.07 m/s (0.05, 0.10), an increase in mean chair rise time of 6% (4%, 8%) and an odds ratio of an inability to balance for 5s of 1.26 (1.02, 1.55). Adjustment for the potential mediating factors, adult SEP and body size attenuated associations greatly. However, despite this attenuation, for walking speed and chair rise time, there was still evidence of moderate associations.</p> <p><b>Conclusions:</b> Policies targeting socioeconomic inequalities in childhood may have additional benefits in promoting the maintenance of independence in later life.</p&gt

Statistical signatures of critical behavior in small systems

The cluster distributions of different systems are examined to search for signatures of a continuous phase transition. In a system known to possess such a phase transition, both sensitive and insensitive signatures are present; while in systems known not to possess such a phase transition, only insensitive signatures are present. It is shown that nuclear multifragmentation results in cluster distributions belonging to the former category, suggesting that the fragments are the result of a continuous phase transition.Comment: 31 pages, two columns with 30 figure

From food to pest: Conversion factors determine switches between ecosystem services and disservices

Ecosystem research focuses on goods and services, thereby ascribing beneficial values to the ecosystems. Depending on the context, however, outputs from ecosystems can be both positive and negative. We examined how provisioning services of wild animals and plants can switch between being services and disservices. We studied agricultural communities in Laos to illustrate when and why these switches take place. Government restrictions on land use combined with economic and cultural changes have created perceptions of rodents and plants as problem species in some communities. In other communities that are maintaining shifting cultivation practices, the very same taxa were perceived as beneficial. We propose conversion factors that in a given context can determine where an individual taxon is located along a spectrum from ecosystem service to disservice, when, and for whom. We argue that the omission of disservices in ecosystem service accounts may lead governments to direct investments at inappropriate targets

Uncoupling mobility and learning: When one does not guarantee the other

Mobile learning was an embedded component of the pedagogical design of an undergraduate course, Digital media and society. In the final semester of 2010 and the first semester of 2011, 135 students participated in an empirical study inquiring into their perceptual experience of mobile learning. To control for access to technology, an optional iPad student loan scheme was used. The iPads were loaded with an electronic textbook and a mobile application of the learning moderation system. Eighty students participated in ten-person focus groups. Feedback on mobility and the electronic text was positive and optimistic. However, the majority of students were not convinced that the trial made a difference to their learning. This result was interpreted to indicate that the presence or absence of mobile devices does not guarantee or preclude student learning. © 2011 Springer-Verlag

Municipal policies and plans of action aiming to promote physical activity and healthy eating habits among schoolchildren in Stockholm, Sweden: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Promoting physical activity and healthy eating habits by structural measures that reach most children in a society is presumably the most sustainable way of preventing development of overweight and obesity in childhood. The main purpose of the present study was to analyse whether policies and plans of action at the central level in municipalities increased the number of measures that aim to promote physical activity and healthy eating habits among schoolchildren aged six to 16. Another purpose was to analyse whether demographic and socio-economic characteristics were associated with the level of such measures.</p> <p>Methods</p> <p>Questionnaires were used to collect data from 25 municipalities and 18 town districts in Stockholm County, Sweden. The questions were developed to capture municipal structural work and factors facilitating physical activity and the development of healthy eating habits for children. Local policy documents and plans of action were gathered. Information regarding municipal demographic and socio-economic characteristics was collected from public statistics.</p> <p>Results</p> <p>Policy documents and plans of action in municipalities and town districts did not seem to influence the number of measures aiming to promote physical activity and healthy eating habits among schoolchildren in Stockholm County. Municipal demographic and socio-economic characteristics were, however, shown to influence the number of measures. In town districts with a high total population size, and in municipalities and town districts with a high proportion of adults with more than 12 years of education, a higher level of health-promoting measures was found. In municipalities with a high annual population growth, the number of measures was lower than in municipalities with a lower annual population growth. Another key finding was the lack of agreement between what was reported in the questionnaires regarding existence and contents of local policies and plans of action and what was actually found when these documents were scrutinized.</p> <p>Conclusion</p> <p>Policy documents and plans of action aiming to promote physical activity and healthy eating habits among schoolchildren aged six to 16 in municipalities and town districts in Stockholm County did not seem to have an impact on the local level of measures. Demographic and socio-economic characteristics of the municipalities and town districts were on the other hand associated with local health-promoting measures.</p