Stringy black holes and energy conditions

The energy condition inequalities for the matter stress energy comprised out of the dilaton and Maxwell fields in the dilaton-Maxwell gravity theories emerging out of string theory are examined in detail. In the simplistic 1+1 dimensional models, $R\le 0$ (where $R$ is the Ricci scalar), turns out to be the requirement for ensuring focusing of timelike geodesics. In 3+1 dimensions, we outline the requirements on matter for pure dilaton theories-these in turn constrain the functional forms of the dilaton. Furthermore, in charged dilaton gravity a curious opposite behaviour of the matter stress energy w.r.t the violation/conservation of the Weak Energy Condition is noted for the electric and magnetic black hole metrics written in the string frame of reference. We also investigate the matter that is necessary for creating certain specific non-asymptotically flat black holes. For the electric and magnetic black hole metrics, strangely, matter satisfies the weak energy condition in the string frame. Finally, the Averaged Null Energy Condition is evaluated along radial null geodesics for each of these black hole spacetimes.Comment: 23 pages, RevTex, no figures, corrected and extended,to appear in Physical Review

Tumor protein D54 defines a new class of intracellular transport vesicles

Transport of proteins and lipids from one membrane compartment to another is via intracellular vesicles. We investigated the function of tumor protein D54 (TPD54/TPD52L2) and found that TPD54 was involved in multiple membrane trafficking pathways: anterograde traffic, recycling, and Golgi integrity. To understand how TPD54 controls these diverse functions, we used an inducible method to reroute TPD54 to mitochondria. Surprisingly, this manipulation resulted in the capture of many small vesicles (30 nm diameter) at the mitochondrial surface. Super-resolution imaging confirmed the presence of similarly sized TPD54-positive structures under normal conditions. It appears that TPD54 defines a new class of transport vesicle, which we term intracellular nanovesicles (INVs). INVs meet three criteria for functionality. They contain specific cargo, they have certain R-SNAREs for fusion, and they are endowed with a variety of Rab GTPases (16 out of 43 tested). The molecular heterogeneity of INVs and the diverse functions of TPD54 suggest that INVs have various membrane origins and a number of destinations. We propose that INVs are a generic class of transport vesicle that transfer cargo between these varied locations

A feasibility study of ‘The StepSmart Challenge’ to promote physical activity in adolescents

Funder: Research Trainees Coordinating Centre; doi: http://dx.doi.org/10.13039/501100000659Abstract: Background: Inactive lifestyles are becoming the norm and creative approaches to encourage adolescents to be more physically active are needed. Little is known about how gamification techniques can be used in physical activity interventions for young people. Such approaches may stimulate interest and encourage physical activity behaviour. The study investigated the feasibility of implementing and evaluating a physical activity intervention for adolescents which included gamification techniques within schools. We tested recruitment and retention strategies for schools and participants, the use of proposed outcome measures, and explored intervention acceptability. Methods: This school-based feasibility study of a randomised cluster trial recruited adolescents aged 12–14 years (n = 224) from five schools (three intervention; two control) in Belfast, Northern Ireland. The 22-week intervention (The StepSmart Challenge) informed by self-determination theory and incorporating gamification strategies involved a school-based pedometer competition. Outcomes, measured at baseline, and post-intervention (at 22 weeks post-baseline and 52 weeks post-baseline) included daily minutes of moderate to vigorous physical activity (MVPA) (measured using ActiGraph accelerometer), mental wellbeing (Warwick-Edinburgh Mental Wellbeing Scale), social support for physical activity, time preference (for delayed and larger rewards or immediate and smaller rewards), pro-social behaviour (Strengths and Difficulties Questionnaire (SDQ)) and the influence of social networks. The intervention’s acceptability was explored in focus groups. Results: We invited 14 schools to participate; eight showed interest in participating. We recruited the first five who responded; all five completed the trial. Of the 236 pupils invited, 224 participated (94.9%): 84.8% (190/224) provided valid MVPA (minutes/day) at baseline and 57.2% (123/215) at 52 weeks. All other outcomes were well completed apart from the SDQ (65% at baseline). Qualitative data highlighted that participants and teachers found The StepSmart Challenge to be an acceptable intervention. Conclusions: The level of interest and high recruitment and retention rates provide support for the feasibility of this trial. The intervention, incorporating gamification strategies and the recruitment methods, using parental opt-out procedures, were acceptable to participants and teachers. Teachers also suggested that the implementation of The StepSmart Challenge could be embedded in a lifelong learning approach to health within the school curriculum. As young people’s lives become more intertwined with technology, the use of innovative gamified interventions could be one approach to engage and motivate health behavioural change in this population. Trial registration: NCT02455986 (date of registration: 28 May 2015)

The Association of Low Birth Weight and Physiological Risk Factors of Hypertension in African American Adolescents

Low birth weight (LBW) has been associated with increased blood pressure and the development of cardiovascular disease including hypertension. Elevated blood pressure, cortisol, and hyperresponsiveness during physiologic stress may function as hypertension biological markers. We examined the association of blood pressure and cortisol levels during induced physiologic stress with LBW in an African American adolescent population (n = 106). METHODS AND RESULTS: Birth weight was obtained from parents. Blood pressure and cortisol levels were measured at rest and in response to an induced physiological stressor. Compared with normal birth weight group (n = 73), the LBW group (n = 33) demonstrated elevated (+4 mm Hg) diastolic pressure (P = .002) and cortisol hyperresponsiveness (P = .05). Seventy-nine percent of LBW adolescents had elevated blood pressure and/or cardiovascular reactivity (P = .04), and 39% had elevated blood pressures. CONCLUSIONS: Low birth weight African American adolescents demonstrated physiological risk factors for hypertension, and these findings add support to the association between LBW and the development of hypertension. © 2007 Lippincott Williams & Wilkins, Inc

The Relationship of Blood Pressure and Cortisol Reactivity to Family History of Hypertension of African American Adolescents

Ethnicity and family history of hypertension (FHH) have been associated with the development of hypertension. Blood pressure and cortisol reactivity during physiologic stress are hypothesized to function as biologic markers for hypertension. The purpose of this study was to explore the relationship of blood pressure and cortisol reactivity physiologic to FHH in a selected sample of African American adolescents. METHODS:: Demographic data and physiologic measurements were obtained from 48 African American adolescents (14-17 years). Reactivity was induced by a cold pressor test of hand immersion in cold water. ‡, t tests, and multivariate repeated-measures analysis were used to determine relationships. RESULTS:: Thirty-one (65%) subjects reported an FHH. Thirty (63%) subjects demonstrated cardiovascular reactivity. Although the mean systolic blood pressure was 4 mm Hg higher, t tests indicated no significance between group in systolic blood pressure (P ≤ .32), diastolic pressure (P ≤ .73), and cortisol (P ≤.81). Blood pressure reactivity of the FHH group was significantly different than the no family history group (P ≤ .0338). Cortisol levels for the total group were markedly elevated (19 nmol/dL) and there was no significant difference in reactivity. CONCLUSION:: African American adolescents with FHH demonstrate increased blood pressure reactivity. Cortisol levels were elevated for all participants. This study adds support to the association of blood pressure reactivity, a biologic marker of HTN and FHH. © 2006 Lippincott Williams & Wilkins, Inc

The determinants of credit ratings in the United Kingdom insurance industry

This paper examines the determinants of external credit ratings attained by insurance firms in the United Kingdom (UK) and of the likelihood that insurers will have such an assessment. Using panel data relating to A.M. Best-rated and Standard and Poor's (S&P)-rated insurers over the period 1993-1997, a trichotomous logit model and an ordered probit model with sample selection are employed to show that the factors which influence the likelihood of having external credit assessments not only vary between the two agencies but also differ from those which determine the ratings themselves. Our results are shown to be of potential interest to participants in the insurance industry and policy-makers alike. Copyright Blackwell Publishers Ltd, 2002.