826 research outputs found

    A Comprehensive Survey of Brane Tilings

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    An infinite class of 4d4d N=1\mathcal{N}=1 gauge theories can be engineered on the worldvolume of D3-branes probing toric Calabi-Yau 3-folds. This kind of setup has multiple applications, ranging from the gauge/gravity correspondence to local model building in string phenomenology. Brane tilings fully encode the gauge theories on the D3-branes and have substantially simplified their connection to the probed geometries. The purpose of this paper is to push the boundaries of computation and to produce as comprehensive a database of brane tilings as possible. We develop efficient implementations of brane tiling tools particularly suited for this search. We present the first complete classification of toric Calabi-Yau 3-folds with toric diagrams up to area 8 and the corresponding brane tilings. This classification is of interest to both physicists and mathematicians alike.Comment: 39 pages. Link to Mathematica modules provide

    Stochastic Transition between Turbulent Branch and Thermodynamic Branch of an Inhomogeneous Plasma

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    Transition phenomena between thermodynamic branch and turbulent branch in submarginal turbulent plasma are analyzed with statistical theory. Time-development of turbulent fluctuation is obtained by numerical simulations of Langevin equation which contains submarginal characteristics. Probability density functions and transition rates between two states are analyzed. Transition from turbulent branch to thermodynamic branch occurs in almost entire region between subcritical bifurcation point and linear stability boundary.Comment: 10 pages, 8 figures, to be published in J. Phys. Soc. Jp

    Rape and respectability: ideas about sexual violence and social class

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    Women on low incomes are disproportionately represented among sexual violence survivors, yet feminist research on this topic has paid very little attention to social class. This article blends recent research on class, gender and sexuality with what we know about sexual violence. It is argued that there is a need to engage with classed distinctions between women in terms of contexts for and experiences of sexual violence, and to look at interactions between pejorative constructions of working-class sexualities and how complainants and defendants are perceived and treated. The classed division between the sexual and the feminine, drawn via the notion of respectability, is applied to these issues. This piece is intended to catalyse further research and debate, and raises a number of questions for future work on sexual violence and social class

    Fires increase Amazon forest productivity through increases in diffuse radiation

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    Atmospheric aerosol scatters solar radiation increasing the fraction of diffuse radiation and the efficiency of photosynthesis. We quantify the impacts of biomass burning aerosol (BBA) on diffuse radiation and plant photosynthesis across Amazonia during 1998-2007. Evaluation against observed aerosol optical depth allows us to provide lower and upper BBA emissions estimates. BBA increases Amazon basin annual mean diffuse radiation by 3.4-6.8% and net primary production (NPP) by 1.4-2.8%, with quoted ranges driven by uncertainty in BBA emissions. The enhancement of Amazon basin NPP by 78-156TgCa-1 is equivalent to 33-65% of the annual regional carbon emissions from biomass burning. This NPP increase occurs during the dry season and acts to counteract some of the observed effect of drought on tropical production. We estimate that 30-60TgCa-1 of this NPP enhancement is within woody tissue, accounting for 8-16% of the observed carbon sink across mature Amazonian forests

    Oral rehydration versus intravenous therapy for treating dehydration due to gastroenteritis in children: a meta-analysis of randomised controlled trials

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    BACKGROUND: Despite treatment recommendations from various organizations, oral rehydration therapy (ORT) continues to be underused, particularly by physicians in high-income countries. We conducted a systematic review of randomised controlled trials (RCTs) to compare ORT and intravenous therapy (IVT) for the treatment of dehydration secondary to acute gastroenteritis in children. METHODS: RCTs were identified through MEDLINE, EMBASE, CENTRAL, authors and references of included trials, pharmaceutical companies, and relevant organizations. Screening and inclusion were performed independently by two reviewers in order to identify randomised or quasi-randomised controlled trials comparing ORT and IVT in children with acute diarrhea and dehydration. Two reviewers independently assessed study quality using the Jadad scale and allocation concealment. Data were extracted by one reviewer and checked by a second. The primary outcome measure was failure of rehydration. We analyzed data using standard meta-analytic techniques. RESULTS: The quality of the 14 included trials ranged from 0 to 3 (Jadad score); allocation concealment was unclear in all but one study. Using a random effects model, there was no significant difference in treatment failures (risk difference [RD] 3%; 95% confidence intervals [CI]: 0, 6). The Mantel-Haenzsel fixed effects model gave a significant difference between treatment groups (RD 4%; 95% CI: 2, 5) favoring IVT. Based on the four studies that reported deaths, there were six in the IVT groups and two in ORT. There were no significant differences in total fluid intake at six and 24 hours, weight gain, duration of diarrhea, or hypo/hypernatremia. Length of stay was significantly shorter for the ORT group (weighted mean difference [WMD] -1.2 days; 95% CI: -2.4,-0.02). Phlebitis occurred significantly more often with IVT (number needed to treat [NNT] 33; 95% CI: 25,100); paralytic ileus occurred more often with ORT (NNT 33; 95% CI: 20,100). These results may not be generalizable to children with persistent vomiting. CONCLUSION: There were no clinically important differences between ORT and IVT in terms of efficacy and safety. For every 25 children (95% CI: 20, 50) treated with ORT, one would fail and require IVT. The results support existing practice guidelines recommending ORT as the first course of treatment in appropriate children with dehydration secondary to gastroenteritis

    Reviewing progress: 7 Year Trends in Characteristics of Adults and Children Enrolled at HIV Care and Treatment Clinics in the United Republic of Tanzania.

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    To evaluate the on-going scale-up of HIV programs, we assessed trends in patient characteristics at enrolment and ART initiation over 7 years of implementation. Data were from Optimal Models, a prospective open cohort study of HIV-infected (HIV+) adults (>=15 years) and children (<15 years) enrolled from January 2005 to December 2011 at 44 HIV clinics in 3 regions of mainland Tanzania (Kagera, Kigoma, Pwani) and Zanzibar. Comparative statistics for trends in characteristics of patients enrolled in 2005--2007, 2008--2009 and 2010--2011 were examined. Overall 62,801 HIV+ patients were enrolled: 58,102(92.5%) adults, (66.5% female); 4,699(7.5%) children.Among adults, pregnant women enrolment increased: 6.8%, 2005--2007; 12.1%, 2008--2009; 17.2%, 2010--2011; as did entry into care from prevention of mother-to-child HIV transmission (PMTCT) programs: 6.6%, 2005--2007; 9.5%, 2008--2009; 12.6%, 2010--2011. WHO stage IV at enrolment declined: 27.1%, 2005--2007; 20.2%, 2008--2009; 11.1% 2010--2011. Of the 42.5% and 29.5% with CD4+ data at enrolment and ART initiation respectively, median CD4+ count increased: 210cells/muL, 2005--2007; 262cells/muL, 2008--2009; 266cells/muL 2010--2011; but median CD4+ at ART initiation did not change (148cells/muL overall). Stavudine initiation declined: 84.9%, 2005--2007; 43.1%, 2008--2009; 19.7%, 2010--2011.Among children, median age (years) at enrolment decreased from 6.1(IQR:2.7-10.0) in 2005--2007 to 4.8(IQR:1.9-8.6) in 2008--2009, and 4.1(IQR:1.5-8.1) in 2010--2011 and children <24 months increased from 18.5% to 26.1% and 31.5% respectively. Entry from PMTCT was 7.0%, 2005--2007; 10.7%, 2008--2009; 15.0%, 2010--2011. WHO stage IV at enrolment declined from 22.9%, 2005--2007, to 18.3%, 2008--2009 to 13.9%, 2010--2011. Proportion initiating stavudine was 39.8% 2005--2007; 39.5%, 2008--2009; 26.1%, 2010--2011. Median age at ART initiation also declined significantly. Over time, the proportion of pregnant women and of adults and children enrolled from PMTCT programs increased. There was a decline in adults and children with advanced HIV disease at enrolment and initiation of stavudine. Pediatric age at enrolment and ART initiation declined. Results suggest HIV program maturation from an emergency response

    Physical activity and fat-free mass during growth and in later life

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    Background: Physical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass. Objectives: A study is presented of the association between FFM and physical activity in relation to age. Methods: In a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants. age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution. Results: PAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males = 18 y old, respectively. In participants < 18 y old, mean FM-adjusted FFM was 1.7 kg (95% CI: 0.1, 3.2 kg) and 3.4 kg (95% CI: 1.0, 5.6 kg) higher in a very active participant with PAL = 2.0 than in a sedentary participant with PAL = 1.5, for females and males, respectively. At age 18 y. height and FM-adjusted FFM was 3.6 kg (95% CI: 2.8, 4.4 kg) and 4.4 kg (95% Cl: 3.2, 5.7 kg) higher. and at age 80 y 0.7 kg (95% CI: -0.2. 1.7 kg) and 1.0 kg (95% CI: -0.1, 2.1 kg) higher. in a participant with PAL = 2.0 than in a participant with PAL = 1.5, for females and males, respectively. Conclusions: If these associations are causal, they suggest physical activity is a major determinant of body composition as reflected in peak FFM, and that a physically active lifestyle can only partly protect against loss of FFM in aging adults.Peer reviewe

    Daylight saving time as a potential public health intervention: an observational study of evening daylight and objectively-measured physical activity among 23,000 children from 9 countries.

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    BACKGROUND: It has been proposed that introducing daylight saving measures could increase children's physical activity, but there exists little research on this issue. This study therefore examined associations between time of sunset and activity levels, including using the bi-annual 'changing of the clocks' as a natural experiment. METHODS: 23,188 children aged 5-16 years from 15 studies in nine countries were brought together in the International Children's Accelerometry Database. 439 of these children were of particular interest for our analyses as they contributed data both immediately before and after the clocks changed. All children provided objectively-measured physical activity data from Actigraph accelerometers, and we used their average physical activity level (accelerometer counts per minute) as our primary outcome. Date of accelerometer data collection was matched to time of sunset, and to weather characteristics including daily precipitation, humidity, wind speed and temperature. RESULTS: Adjusting for child and weather covariates, we found that longer evening daylight was independently associated with a small increase in daily physical activity. Consistent with a causal interpretation, the magnitude of these associations was largest in the late afternoon and early evening and these associations were also evident when comparing the same child just before and just after the clocks changed. These associations were, however, only consistently observed in the five mainland European, four English and two Australian samples (adjusted, pooled effect sizes 0.03-0.07 standard deviations per hour of additional evening daylight). In some settings there was some evidence of larger associations between daylength and physical activity in boys. There was no evidence of interactions with weight status or maternal education, and inconsistent findings for interactions with age. CONCLUSIONS: In Europe and Australia, evening daylight seems to play a causal role in increasing children's activity in a relatively equitable manner. Although the average increase in activity is small in absolute terms, these increases apply across all children in a population. Moreover, these small effect sizes actually compare relatively favourably with the typical effect of intensive, individual-level interventions. We therefore conclude that, by shifting the physical activity mean of the entire population, the introduction of additional daylight saving measures could yield worthwhile public health benefits
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