Heritability of risk-taking in adolescence: A longitudinal twin study

Adolescents are prone to risk-taking behaviors leading to adverse consequences such as substance abuse, accidents, violence, and victimization. However, little is known about the contribution of genetic and environmental factors to individual differences in the propensity for risk-taking. This study investigated developmental changes, longitudinal stability, and heritability of risk-taking using data from 752 adolescent twins including 169 MZ and 203 DZ pairs. The Balloon Analogue Risk Task (BART), an experimental behavioral measure of risk taking, was administered to the twins at age 12 and then re-administered to a part of this sample at age 14. Risk-taking increased with age, but individual differences showed a significant longitudinal stability. Genetic model fitting showed that at age 12, heritability of risk-taking was modest but significant in both sexes, whereas at age 14, heritability increased to 55% in males and became non-significant in females. The findings suggest that propensity for risk-taking as measured by BART can be a useful endophenotype for genetic studies of adolescent externalizing psychopathology, however, the utility of this measure may be limited by sex differences in heritability

Existence of equilibria in countable games: an algebraic approach

Although mixed extensions of finite games always admit equilibria, this is not the case for countable games, the best-known example being Wald's pick-the-larger-integer game. Several authors have provided conditions for the existence of equilibria in infinite games. These conditions are typically of topological nature and are rarely applicable to countable games. Here we establish an existence result for the equilibrium of countable games when the strategy sets are a countable group and the payoffs are functions of the group operation. In order to obtain the existence of equilibria, finitely additive mixed strategies have to be allowed. This creates a problem of selection of a product measure of mixed strategies. We propose a family of such selections and prove existence of an equilibrium that does not depend on the selection. As a byproduct we show that if finitely additive mixed strategies are allowed, then Wald's game admits an equilibrium. We also prove existence of equilibria for nontrivial extensions of matching-pennies and rock-scissors-paper. Finally we extend the main results to uncountable games

Hypothermia Due to an Ascending Impairment of Shivering in Hyperacute Experimental Allergic Encephalomyelitis in the Lewis Rat

Severe hypothermia and an ascending impairment of shivering are previously undescribed clinical signs in hyperacute experimental allergic encephalomyelitis (EAE) in the Lewis rat. These occurred in hyperacute EAE induced by inoculation with guinea pig spinal cord homogenate and heat-killed Bordetella pertussis. Hypothermia was first detected on day 6-7 post-inoculation, within 12-24 h of the onset of neurological signs, and became more severe as the disease progressed. Rectal temperatures less than or equal to 30 degrees C were common at ambient temperatures of 19-22 degrees C. Shivering was assessed by palpation and by cold tremor electromyography. Shivering was absent in the tail by day 6-7 post-inoculation. The impairment then progressed to affect the hindlimbs, thorax and occasionally the forelimbs. Shivering was absent in hindlimbs with only mild or moderate weakness. Histological studies revealed perivascular inflammation with polymorphonuclear and mononuclear cells, oedema, fibrin deposition, haemorrhage, primary demyelination and axonal degeneration in the spinal cord, dorsal root ganglia and spinal roots. The brainstem was also involved but the cerebral hemispheres, including the hypothalamus, were spared. The close relationship between the severity of hypothermia and the extent of shivering impairment indicates that reduced shivering is an important cause of hypothermia in hyperacute EAE. It is concluded that this impairment of shivering is due not to hypothalamic damage but to lesions elsewhere in the central and peripheral nervous systems

Head up ; an interdisciplinary, participatory and co-design process informing the development of a novel neck support for people living with progressive neck muscle weakness

This paper presents the Head-Up project that aims to provide innovative head support to help improve posture, relieve pain and aid communication for people living with progressive neck muscle weakness. The initial focus is motor neurone disease. The case study illustrates collaborative, interdisciplinary research and new product development underpinned by participatory design. The study was initiated by a two-day stakeholder workshop followed by early proof-of-concept modeling and patient need evidence building. The work subsequently led to a successful NIHR i4i application funding a 24-month iterative design process, patenting, CE marking and clinical evaluation. The evaluation has informed amendments to the proposed design we refer to here as the Sheffield Support Snood (SSS). The outcome positively demonstrates use and performance improvements over current neck orthoses and, the process of multidisciplinary and user engagement has created a sense of ownership by MND participants, who have since acted as advocates for the product.</p

Diurnal preference and sleep quality: same genes? A study of young adult twins

The aims of this study were to examine the genetic and environmental influences on diurnal preference and sleep quality, the association between these phenotypes, the genetic and environmental influences on this association, and the magnitude of overlap between these influences. Using a twin design, data on diurnal preference (measured by the Morningness-Eveningness Questionnaire) and sleep quality (measured by the Pittsburgh Sleep Quality Index) were collected from 420 monozygotic twins, 773 dizygotic twins, and 329 siblings (mode age = 20 yrs, range = 18–27 yrs) from a population-based twin registry across the UK. Univariate analyses indicated that dominance genetic influence accounted for 52% and non-shared environment 48% of variance in diurnal preference. For sleep quality, additive genetic influence explained 43% and non-shared environment 57% of the variance. The bivariate analysis indicated a significant association between greater eveningness preference and poorer sleep quality (r = .27). There was substantial overlap in the additive genetic influences on both phenotypes (rA = .57), and overlap in the dominance genetic influences common to both phenotypes was almost absolute (rD = .99). Overlap in non-shared environment was much smaller (rE = .02). Additive genetic influence accounted for 2% of the association, dominance genetic influence accounted for 94%, and non-shared environmental influences accounted for the remaining 4%. The substantial overlap in genetic influence between these phenotypes indicates that similar genes are important for diurnal preference and sleep quality. Therefore, those genes already known to influence one phenotype may be possible candidates to explore with regards to the other phenotype

Assessing the cost of global biodiversity and conservation knowledge

Knowledge products comprise assessments of authoritative information supported by stan-dards, governance, quality control, data, tools, and capacity building mechanisms. Considerable resources are dedicated to developing and maintaining knowledge productsfor biodiversity conservation, and they are widely used to inform policy and advise decisionmakers and practitioners. However, the financial cost of delivering this information is largelyundocumented. We evaluated the costs and funding sources for developing and maintain-ing four global biodiversity and conservation knowledge products: The IUCN Red List ofThreatened Species, the IUCN Red List of Ecosystems, Protected Planet, and the WorldDatabase of Key Biodiversity Areas. These are secondary data sets, built on primary datacollected by extensive networks of expert contributors worldwide. We estimate that US$160million (range: US$116–204 million), plus 293 person-years of volunteer time (range: 278–308 person-years) valued at US$14 million (range US$12–16 million), were invested inthese four knowledge products between 1979 and 2013. More than half of this financingwas provided through philanthropy, and nearly three-quarters was spent on personnelcosts. The estimated annual cost of maintaining data and platforms for three of these knowl-edge products (excluding the IUCN Red List of Ecosystems for which annual costs were notpossible to estimate for 2013) is US$6.5 million in total (range: US$6.2–6.7 million). We esti-mated that an additional US$114 million will be needed to reach pre-defined baselines ofdata coverage for all the four knowledge products, and that once achieved, annual mainte-nance costs will be approximately US$12 million. These costs are much lower than those tomaintain many other, similarly important, global knowledge products. Ensuring that biodi-versity and conservation knowledge products are sufficiently up to date, comprehensiveand accurate is fundamental to inform decision-making for biodiversity conservation andsustainable development. Thus, the development and implementation of plans for sustain-able long-term financing for them is critical