129 research outputs found
Analytical approximation for the structure of differentially rotating barotropes
Approximate analytical formula for density distribution in differentially
rotating stars is derived. Any barotropic EOS and conservative rotation law can
be handled with use of this method for wide range of differential rotation
strength. Results are in good qualitative agreement with comparison to the
other methods. Some applications are suggested and possible improvements of the
formula are discussed.Comment: 10 pages, 13 figures, accepted for publication in Monthly Notice
DNA methylation and body mass index:investigating identified methylation sites at HIF3A in a causal framework
Multiple differentially methylated sites and regions associated with adiposity have now been identified in large-scale cross-sectional studies. We tested for replication of associations between previously identified CpG sites at HIF3A and adiposity in ∼1,000 mother-offspring pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC). Availability of methylation and adiposity measures at multiple time points, as well as genetic data, allowed us to assess the temporal associations between adiposity and methylation and to make inferences regarding causality and directionality. Overall, our results were discordant with those expected if HIF3A methylation has a causal effect on BMI and provided more evidence for causality in the reverse direction (i.e., an effect of BMI on HIF3A methylation). These results are based on robust evidence from longitudinal analyses and were also partially supported by Mendelian randomization analysis, although this latter analysis was underpowered to detect a causal effect of BMI on HIF3A methylation. Our results also highlight an apparent long-lasting intergenerational influence of maternal BMI on offspring methylation at this locus, which may confound associations between own adiposity and HIF3A methylation. Further work is required to replicate and uncover the mechanisms underlying the direct and intergenerational effect of adiposity on DNA methylation.Rebecca C. Richmond, Gemma C. Sharp, Mary E. Ward, Abigail Fraser, Oliver Lyttleton, Wendy L. McArdle, Susan M. Ring, Tom R. Gaunt, Debbie A. Lawlor, George Davey Smith, and Caroline L. Relto
Thermodynamics of a black hole in a cavity
We present a unified thermodynamical description of the configurations
consisting on self-gravitating radiation with or without a black hole. We
compute the thermal fluctuations and evaluate where will they induce a
transition from metastable configurations towards stable ones. We show that the
probability of finding such a transition is exponentially small. This indicates
that, in a sequence of quasi equilibrium configurations, the system will remain
in the metastable states till it approaches very closely the critical point
beyond which no metastable configuration exists. Near that point, we relate the
divergence of the local temperature fluctuations to the approach of the
instability of the whole system, thereby generalizing the usual fluctuations
analysis in the cases where long range forces are present. When angular
momentum is added to the cavity, the above picture is slightly modified.
Nevertheless, at high angular momentum, the black hole loses most of its mass
before it reaches the critical point at which it evaporates completely.Comment: 27 pages, latex file, contains 3 figures available on request at
[email protected]
Acupuncture to improve live birth rates for women undergoing in vitro fertilization: a protocol for a randomized controlled trial
BACKGROUND: IVF is a costly treatment option for women, their partners, and the public. Therefore new therapies that improve reproductive and health outcomes are highly desirable. There is a growing body of research evaluating the effect of acupuncture administered during IVF, and specifically on the day of embryo transfer (ET). Many trials are heterogeneous and results inconsistent. There remains insufficient evidence to determine if acupuncture can enhance live birth rates when used as an adjunct to IVF treatment. The study will determine the clinical effectiveness of acupuncture with improving the proportion of women undergoing IVF having live births. Other objectives include: determination of the cost effectiveness of IVF with acupuncture; and examination of the personal and social context of acupuncture in IVF patients, and examining the reasons why the acupuncture may or may not have worked. METHODS: We will conduct a randomized controlled trial of acupuncture compared to placebo acupuncture. Inclusion criteria include: women aged less than 43 years; undergoing a fresh IVF or ICSI cycle; and restricted to women with the potential for a lower live birth rate defined as two or more previous unsuccessful ETs; and unsuccessful clinical pregnancies of quality embryos deemed by the embryologist to have been suitable for freezing by standard criteria. Women will be randomized to acupuncture or placebo acupuncture. Treatment is administered on days 6 to 8 of the stimulated cycle and two treatments on the day of ET. A non-randomized cohort of women not using acupuncture will be recruited to the study. The primary study outcome is the proportion of women reporting a live birth. Secondary outcomes include the proportion of women reporting a clinical pregnancy miscarriage prior to 12 weeks, quality of life, and self-efficacy. The sample size of the study is 1,168 women, with the aim of detecting a 7% difference in live births between groups (P = 0.05, 80% power). DISCUSSION: There remains a need for further research to add significant new knowledge to defining the exact role of certain acupuncture protocols in the management of infertility requiring IVF from a clinical and cost-effectiveness perspective.Caroline A. Smith, Sheryl de Lacey, Michael Chapman, Julie Ratcliffe, Robert J. Norman, Neil Johnson, Gavin Sacks, Jane Lyttleton and Clare Boothroy
Prenatal and early life influences on epigenetic age in children:a study of mother-offspring pairs from two cohort studies
DNA methylation-based biomarkers of aging are highly correlated with actual age. Departures of methylation-estimated age from actual age can be used to define epigenetic measures of child development or age acceleration (AA) in adults. Very little is known about genetic or environmental determinants of these epigenetic measures of aging. We obtained DNA methylation profiles using Infinium HumanMethylation450 BeadChips across five time-points in 1018 mother-child pairs from the Avon Longitudinal Study of Parents and Children. Using the Horvath age estimation method, we calculated epigenetic age for these samples. AA was defined as the residuals from regressing epigenetic age on actual age. AA was tested for associations with cross-sectional clinical variables in children. We identified associations between AA and sex, birth weight, birth by caesarean section and several maternal characteristics in pregnancy, namely smoking, weight, BMI, selenium and cholesterol level. Offspring of non-drinkers had higher AA on average but this difference appeared to resolve during childhood. The associations between sex, birth weight and AA found in ARIES were replicated in an independent cohort (GOYA). In children, epigenetic AA measures are associated with several clinically relevant variables, and early life exposures appear to be associated with changes in AA during adolescence. Further research into epigenetic aging, including the use of causal inference methods, is required to better our understanding of aging
Maternal pre-pregnancy BMI and gestational weight gain, offspring DNA methylation and later offspring adiposity: Findings from the Avon Longitudinal Study of Parents and Children
Evidence suggests that in utero exposure to undernutrition and overnutrition might affect adiposity in later life. Epigenetic modification is suggested as a plausible mediating mechanism.We used multivariable linear regression and a negative control design to examine offspring epigenome-wide DNA methylation in relation to maternal and offspring adiposity in 1018 participants.Compared with neonatal offspring of normal weight mothers, 28 and 1621 CpG sites were differentially methylated in offspring of obese and underweight mothers, respectively [false discovert rate (FDR)-corrected P-value < 0.05), with no overlap in the sites that maternal obesity and underweight relate to. A positive association, where higher methylation is associated with a body mass index (BMI) outside the normal range, was seen at 78.6% of the sites associated with obesity and 87.9% of the sites associated with underweight. Associations of maternal obesity with offspring methylation were stronger than associations of paternal obesity, supporting an intrauterine mechanism. There were no consistent associations of gestational weight gain with offspring DNA methylation. In general, sites that were hypermethylated in association with maternal obesity or hypomethylated in association with maternal underweight tended to be positively associated with offspring adiposity, and sites hypomethylated in association with maternal obesity or hypermethylated in association with maternal underweight tended to be inversely associated with offspring adiposity.Our data suggest that both maternal obesity and, to a larger degree, underweight affect the neonatal epigenome via an intrauterine mechanism, but weight gain during pregnancy has little effect. We found some evidence that associations of maternal underweight with lower offspring adiposity and maternal obesity with greater offspring adiposity may be mediated via increased DNA methylation.Gemma C Sharp, Debbie A Lawlor, Rebecca C Richmond, Abigail Fraser, Andrew Simpkin, Matthew Suderman, Hashem A Shihab, Oliver Lyttleton, Wendy McArdle, Susan M Ring, Tom R Gaunt, George Davey Smith and Caroline L Relto
Gravitational drag on a point mass in hypersonic motion through a gaseous medium
We explore a ballistic orbit model to infer the gravitational drag force on
an accreting point mass M, such as a black hole, moving at a hypersonic
velocity v_{0} through a gaseous environment of density \rho_{0}. The
streamlines blend in the flow past the body and transfer momentum to it. The
total drag force acting on the body, including the nonlinear contribution of
those streamlines with small impact parameter that bend significantly and pass
through a shock, can be calculated by imposing conservation of momentum. In
this fully analytic approach, the ambiguity in the definition of the lower
cut-off distance in calculations of the effect of dynamical
friction is removed. It turns out that .
Using spherical surfaces of control of different sizes, we carry out a
successful comparison between the predicted drag force and the one obtained
from a high resolution, axisymmetric, isothermal flow simulation. We
demonstrate that ballistic models are reasonably successful in accounting for
both the accretion rate and the gravitational drag.Comment: 8 pages, 6 figures, accepted to MNRA
Care seeking behaviour and barriers to accessing services for sexually transmitted infections among female sex workers in Laos: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Prompt, correct diagnosis and treatment with health information are essential components of reproductive tract infection (RTI) and sexually transmitted infection (STI) services. This study aims to describe care seeking behaviour and barriers to accessing RTI/STI services among female sex workers (FSWs) in Laos.</p> <p>Methods</p> <p>A cross-sectional survey using closed and open-ended questions was performed in six districts along Road 9, traversing Savannakhet province from Thailand to Vietnam. In total, 407 FSWs were interviewed. The data were analyzed and presented descriptively. Multiple logistic regression analysis was applied to assess associations between respondents' background characteristics and care seeking behaviour.</p> <p>Results</p> <p>About half of the respondents (49%) were less than or equal to 19 years of age, and 50% had started or completed secondary school. Fifty-eight percent had been engaged in sex work for less than 1 year. Eighty-six percent of the respondents reported RTI/STI signs or symptoms currently or in the last 3 months but only two-thirds of those with symptoms sought treatment. Source of treatment for the last RTI/STI episode was the drop-in centre (53%) followed by a public hospital (23%), private clinic (12%), private pharmacy (9%), and herbalist (2%). The main barriers to service use were long waiting time, inconvenient location of the clinic, not knowing where to get the services needed, and negative attitudes among healthcare providers. Care seeking behaviour was associated with longer duration of sex work (OR = 2.6, 95%CI 1.52-5.36). Forty-four percent received health information from peer educators, 34% from fellow friends, 26% from a pimp, and 26% had received information from a healthcare provider during the visit.</p> <p>Conclusion</p> <p>There were several barriers to accessing RTI/STI services and they were related to both structural and individual factors. Innovative STI service strategies to inform FSWs about the importance of early diagnosis and treatment should be established. Continuous training for STI service providers focusing on counseling skills and awareness of the sexual health care needs for FSWs is recommended in order to minimize the barriers experienced by FSWs in this particular setting.</p
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Evaluation of the Social Services and Well-being (Wales) Act 2014: Literature Review
The author list for the literature review is provided below:
Evaluation of the Social Services and Well-being (Wales) Act 2014: Literature Review
Chapter authors:
Introduction and methods
Verity, F., Wallace, S., Llewellyn, M., Anderson, P. and Lyttleton-Smith, J.
Well-being
Anderson, P., Lyttleton-Smith, J., Kosnes, L., Read, S., Blackmore, H. and Williams, Z.
Prevention and early intervention
Verity, F., Read, S. and Richards, J.
Co-production
Andrews, N., Calder, G., Blanluet, N., Tetlow, S. and Wallace, S.
Multi-agency
Wallace, C., Orrell, A., Garthwaite, T., Tetlow, S. and Wallace, S.
Voice and control
Llewellyn, M., Saltus, R., Blackmore, H., Tetlow, S., Williams, Z. and Wallace, S.
Financial and economic
Phillips, C., Prowle, M., Tetlow, S. and Williams, Z.
Service user and carer experiences under the Act
Wallace, S.This report is a summary of the extensive review of the literature to inform the evaluation of the Social Services and Well-being (Wales) Act 2014. This document is a summary of the extensive review of the literature undertaken to inform the evaluation of the Social Services and Well-being (Wales) Act 2014 (hereafter referred to as ‘the Act’).1 The Welsh Government has commissioned a partnership between academics across four universities in Wales and expert advisers to deliver the evaluation. The Act sets out a government vision to produce ‘transformative changes’ in social service public policy, regulations, and delivery arrangements across Wales. It has 11 parts and is informed by five principles that set out a vision to produce transformative changes in public policy, regulations, and service delivery. Aligned to it are structures, processes, and codes of practice. The Evaluation of the Act – a study called IMPACT – is organised around each of the five principles together with a focus on the financial and economic aspects of the Act’s implementation. The approach to undertaking this evaluation research is to structure the evaluation by using the fundamental principles of the Act as the scaffolding. These principles are: • Well-being • Prevention • Co-Production • Multi-agency working • Voice and control There is also a focus on the financial and economic considerations of the implementation of the Act and this area constitutes the sixth evaluation study theme
Recommended from our members
Evaluation of the Social Services and Well-being (Wales) Act 2014: Literature Review
Evaluation of the Social Services and Well-being (Wales) Act 2014: Literature Review
Edited by:
Llewellyn, M., Verity, F. and Wallace, S.
Chapter authors:
Chapter 1: Evaluation Overview and Literature Methodology
Verity, F., Wallace, S., Llewellyn, M., Anderson, P. and Lyttleton-Smith, J.
Chapter 2: Well-being literature review
Anderson, P., Lyttleton-Smith, J., Kosnes, L., Read, S., Blackmore, H. and Williams, Z.
Chapter 3: Prevention and early intervention literature review
Verity, F., Read, S. and Richards, J.
Chapter 4: Co-production literature review
Andrews, N., Calder, G., Blanluet, N., Tetlow, S. and Wallace, S.
Chapter 5: Multi-agency literature review
Wallace, C., Orrell, A., Garthwaite, T., Tetlow, S. and Wallace, S.
Chapter 6: Voice and control literature review
Llewellyn, M., Saltus, R., Blackmore, H., Tetlow, S., Williams, Z. and Wallace, S.
Chapter 7: Financial and economic literature review
Phillips, C., Prowle, M., Tetlow S. and Williams Z.Mae’r ddogfen yma hefyd ar gael yn Gymraeg. This document is also available in Welsh. OGL © Crown Copyright Digital ISBN 978-1-80038-948-9.This document is a summary of the extensive review of the literature to inform the evaluation of the Social Services and Well-being (Wales) Act 2014 (hereafter referred to as ‘the Act’).Welsh Governmen
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