Branes on the Horizon

Models with extra dimensions are often invoked to resolve cosmological problems. We investigate the possibility of apparent acausality as seen by a brane-based observer resulting from signal propagation through the extra dimensions. Null geodesics are first computed in static and cosmological single-brane models, following which we derive the equations of motion for the inter-brane distance in a two-brane scenario, which we use to examine possible acausality in this more complex setup. Despite observing significant effective acausality in some situations there is no a priori solution to the horizon problem using this mechanism. In the two-brane scenario there can be significant late time violation of gravitational Lorentz invariance, resulting in the gravitational horizon being larger than the particle horizon, leading to potential signals in gravitational wave detectors

Clustering and stalling of North Atlantic cyclones: the influence on precipitation in England and Wales

Recently, several large-scale flooding events in England and Wales have been caused by multiple cyclones in a short period of time (clustering), or slow moving storms (stalling). The question of how much precipitation is associated with clustered or stalled extratropical cyclones is addressed using continuous areas of precipitation to associate extreme precipitation events to specific extratropical cyclones. This method is applied to ERAInterim/HadUKP data and the HadGEM2-ES Historical and RCP8.5 climate model experiments for 1, 7, 13 and 31-day precipitation accumulations. In ERA-Interim, extreme wet events (p ≥ 0.98) in England and Wales are associated with 20% to 45% more cyclones than wet events (p ≥ 0.5) in winter, spring and autumn. Mean cyclone residence times are generally longer in extreme wet events than wet events for all seasons. Longer residence times are associated with a quasi-stationary wavenumber 6 planetary wave in spring, summer and autumn. Clustering is a less important process for extreme England and Wales precipitation events in HadGEM2-ES than in ERA-Interim. Stalling as important for summer extreme wet events in HadGEM2-ES as in ERA-Interim, however, stalling in winter extreme events is under-represented. Projected increases in extreme winter England and Wales precipitation events in HadGEM2-ES are primarily associated with increased atmospheric moisture availability rather than changes to clustering or stalling. The ability of reanalyses to represent extreme England and Wales precipitation is also evaluated. ERA-Interim and 20CR only identify 45% to 55% of observed daily p98 precipitation events over England and Wales. Clustering and stalling are significant influences on England and Wales precipitation, mainly affecting winter and summer precipitation events respectively. However, future changes in England and Wales precipitation are likely to be governed more by thermodynamic changes than changes in circulation patterns

Thermal Performance Testing of EMU and CSAFE Liquid Cooling Gannents

Future exploration missions require the development of a new liquid cooling garment (LCG) to support the next generation extravehicular activity (EVA) suit system. The new LCG must offer greater system reliability, optimal thermal performance as required by mission directive, and meet other design requirements including improved tactile comfort. To advance the development of a future LCG, a thermal performance test was conducted to evaluate: (1) the comparable thermal performance of the EMU LCG and the CSAFE developed engineering evaluation unit (EEU) LCG, (2) the effect of the thermal comfort undergarment (TCU) on the EMU LCG tactile and thermal comfort, and (3) the performance of a torso or upper body only LCG shirt to evaluate a proposed auxiliary loop. To evaluate the thermal performance of each configuration, a metabolic test was conducted using the Demonstrator Spacesuit to create a relevant test environment. Three (3) male test subjects of similar height and weight walked on a treadmill at various speeds to produce three different metabolic loads - resting (300-600 BTU/hr), walking at a slow pace (1200 BTU/hr), and walking at a brisk pace (2200 BTU/hr). Each subject participated in five tests - two wearing the CSAFE full LCG, one wearing the EMU LCG without TCUs, one wearing the EMU LCG with TCUs, and one with the CSAFE shirt-only. During the test, performance data for the breathing air and cooling water systems and subject specific data was collected to define the thermal performance of the configurations. The test results show that the CSAFE EEU LCG and EMU LCG with TCU had comparable performance. The testing also showed that an auxiliary loop LCG, sized similarly to the shirt-only configuration, should provide adequate cooling for contingency scenarios. Finally, the testing showed that the TCU did not significantly hinder LCG heat transfer, and may prove to be acceptable for future suit use with additional analysis and testing

Cross-cultural effects of color, but not morphological masculinity, on perceived attractiveness of men's faces

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 ElsevierMuch attractiveness research has focused on face shape. The role of masculinity (which for adults is thought to be a relatively stable shape cue to developmental testosterone levels) in male facial attractiveness has been examined, with mixed results. Recent work on the perception of skin color (a more variable cue to current health status) indicates that increased skin redness, yellowness, and lightness enhance apparent health. It has been suggested that stable cues such as masculinity may be less important to attractiveness judgments than short-term, more variable health cues. We examined associations between male facial attractiveness, masculinity, and skin color in African and Caucasian populations. Masculinity was not found to be associated with attractiveness in either ethnic group. However, skin color was found to be an important predictor of attractiveness judgments, particularly for own-ethnicity faces. Our results suggest that more plastic health cues, such as skin color, are more important than developmental cues such as masculinity. Further, unfamiliarity with natural skin color variation in other ethnic groups may limit observers' ability to utilize these color cues

The relationship between VO2 max and 1200m shuttle run performance in elite academy football players

Purpose: To investigate the relationship between VO2 max and performance in the 1200m shuttle run test in elite Premier League academy football players. Methods: Seventeen male professional outfield football players completed a laboratory based incremental treadmill test to establish vVO2 max and a field based 1200m shuttle test to estimate velocity at MAS. During the pre-season period a linear speed phase consisting of twice weekly PS exposures were conducted and each player’s PS reached during this period was established. Body composition was measured using DEXA. Results: Examining the standardized (scaled) coefficients, ASR (7.373) had the largest effect on VO2 max followed by PS (-5.568), MAS (3.604), Body Fat (-0.285) and Lean Mass (-0.185).The results suggest that the model is a significantly better predictor than a model that constantly predicts the mean VO2max value (F = 3.422, p = 0.041). Conclusions: The MAS values obtained from the 1200m shuttle test may be an appropriate assessment to consider when monitoring and individualizing high-intensity performance rather than the generic threshold of 5.5 m/s.info:eu-repo/semantics/publishedVersio

Immune function during early adolescence positively predicts adult facial sexual dimorphism in both men and women

Evolutionary theories suggest that humans prefer sexual dimorphism in faces because masculinity in men and femininity in women may be an indicator of immune function during development. In particular, the immunocompetence handicap hypothesis proposes that sexual dimorphism indicates good immune function during development because the sex hormones, particularly testosterone in men, required for the development of sexually dimorphic facial features also taxes the immune system. Therefore, only healthy males can afford the high level of testosterone for the development of sexually dimorphic traits without compromising their survival. Researchers have suggested that a similar mechanism via the effects of oestrogen might also explain male preferences for female femininity. Despite the prominence of the immunocompetence handicap hypothesis, no studies have tested whether immune function during development predicts adult facial sexual dimorphism. Here, using data from a longitudinal public health dataset, the Western Australian Pregnancy Cohort (Raine) Study (Generation 2), we show that some aspects of immune function during early adolescence (14 years) positively predict sexually dimorphic 3D face shape in both men and women. Our results support a fundamental assumption that facial sexual dimorphism is an indicator of immune function during the development of facial sexual dimorphism.PostprintPeer reviewe

Prevalence and Correlates of Youth Suicidal Ideation and Attempts: Evidence from the 2014 Ontario Child Health Study

© The Author(s) 2019. Objectives: To present the 12-month prevalence and correlates of suicidal ideation and attempts in a sample of youth in Ontario. Methods: Data come from the 2014 Ontario Child Health Study, a provincially representative survey of families with children in Ontario. Youth aged 14 to 17 y (n = 2,396) completed a computer-assisted, self-administered questionnaire in their home to assess the occurrence of suicidal ideation, suicidal attempts, and associated correlates, including non-suicidal self-injury, mental disorders, substance use, peer victimization and exposure to child maltreatment. Socio-demographic information was collected from the parent. Logistic regression models were used to identify correlates that distinguished between youth reporting: 1) no suicidal ideation or attempts, 2) suicidal ideation but no attempts, and 3) suicidal ideation and attempts. Results: The 12-month prevalence of suicidal ideation and attempts was 8.1% and 4.3%, respectively. All clinical and behavioural correlates were significantly higher among youth reporting suicidal ideation or attempts, as compared with non-suicidal youth. In adjusted models, depression and non-suicidal self-injury were each independently associated with elevated odds of suicidal ideation (OR = 4.84 and 4.19, respectively) and suicidal attempt (OR = 7.84 and 22.72, respectively). Among youth who reported suicidal ideation, the only variable that differentiated youth who attempted suicide v. those who did not, in adjusted models, was non-suicidal self-injury (OR = 3.89). Conclusions: Suicidal ideation and attempts are common among youth in Ontario, often co-occurring with mental disorders and high-risk behaviours. These findings underscore the need for effective prevention and intervention strategies, particularly for youth depression and non-suicidal self-injury