79 research outputs found

    UV Luminosity Functions from 132 z~7 and z~8 Lyman-Break Galaxies in the ultra-deep HUDF09 and wide-area ERS WFC3/IR Observations

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    We identify 73 z~7 and 59 z~8 candidate galaxies in the reionization epoch, and use this large 26-29.4 AB mag sample of galaxies to derive very deep luminosity functions to <-18 AB mag and the star formation rate density at z~7 and z~8. The galaxy sample is derived using a sophisticated Lyman-Break technique on the full two-year WFC3/IR and ACS data available over the HUDF09 (~29.4 AB mag, 5 sigma), two nearby HUDF09 fields (~29 AB mag, 14 arcmin) and the wider area ERS (~27.5 AB mag) ~40 arcmin**2). The application of strict optical non-detection criteria ensures the contamination fraction is kept low (just ~7% in the HUDF). This very low value includes a full assessment of the contamination from lower redshift sources, photometric scatter, AGN, spurious sources, low mass stars, and transients (e.g., SNe). From careful modelling of the selection volumes for each of our search fields we derive luminosity functions for galaxies at z~7 and z~8 to <-18 AB mag. The faint-end slopes alpha at z~7 and z~8 are uncertain but very steep at alpha = -2.01+/-0.21 and alpha=-1.91+/-0.32, respectively. Such steep slopes contrast to the local alpha<~-1.4 and may even be steeper than that at z~4 where alpha=-1.73+/-0.05. With such steep slopes (alpha<~-1.7) lower luminosity galaxies dominate the galaxy luminosity density during the epoch of reionization. The star formation rate densities derived from these new z~7 and z~8 luminosity functions are consistent with the trends found at later times (lower redshifts). We find reasonable consistency, with the SFR densities implied from reported stellar mass densities, being only ~40% higher at z<7. This suggests that (1) the stellar mass densities inferred from the Spitzer IRAC photometry are reasonably accurate and (2) that the IMF at very high redshift may not be very different from that at later times.Comment: 38 pages, 21 figures, 20 tables, ApJ, accepted for publicatio

    Association between full service and fast food restaurant density, dietary intake and overweight/obesity among adults in Delhi, India

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    Abstract Background The food environment has been implicated as an underlying contributor to the global obesity epidemic. However, few studies have evaluated the relationship between the food environment, dietary intake, and overweight/obesity in low- and middle-income countries (LMICs). The aim of this study was to assess the association of full service and fast food restaurant density with dietary intake and overweight/obesity in Delhi, India. Methods Data are from a cross-sectional, population-based study conducted in Delhi. Using multilevel cluster random sampling, 5364 participants were selected from 134 census enumeration blocks (CEBs). Geographic information system data were available for 131 CEBs (n = 5264) from a field survey conducted using hand-held global positioning system devices. The number of full service and fast food restaurants within a 1-km buffer of CEBs was recorded by trained staff using ArcGIS software, and participants were assigned to tertiles of full service and fast food restaurant density based on their resident CEB. Height and weight were measured using standardized procedures and overweight/obesity was defined as a BMI ≥25 kg/m2. Results The most common full service and fast food restaurants were Indian savory restaurants (57.2%) and Indian sweet shops (25.8%). Only 14.1% of full service and fast food restaurants were Western style. After adjustment for age, household income, education, and tobacco and alcohol use, participants in the highest tertile of full service and fast food restaurant density were less likely to consume fruit and more likely to consume refined grains compared to participants in the lowest tertile (both p < 0.05). In unadjusted logistic regression models, participants in the highest versus lowest tertile of full service and fast food restaurant density were significantly more likely to be overweight/obese: odds ratio (95% confidence interval), 1.44 (1.24, 1.67). After adjustment for age, household income, and education, the effect was attenuated: 1.08 (0.92, 1.26). Results were consistent with further adjustment for tobacco and alcohol use, moderate physical activity, and owning a bicycle or motorized vehicle. Conclusions Most full service and fast food restaurants were Indian, suggesting that the nutrition transition in this megacity may be better characterized by the large number of unhealthy Indian food outlets rather than the Western food outlets. Full service and fast food restaurant density in the residence area of adults in Delhi, India, was associated with poor dietary intake. It was also positively associated with overweight/obesity, but this was largely explained by socioeconomic status. Further research is needed exploring these associations prospectively and in other LMICs

    Selective Pressures to Maintain Attachment Site Specificity of Integrative and Conjugative Elements

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    Integrative and conjugative elements (ICEs) are widespread mobile genetic elements that are usually found integrated in bacterial chromosomes. They are important agents of evolution and contribute to the acquisition of new traits, including antibiotic resistances. ICEs can excise from the chromosome and transfer to recipients by conjugation. Many ICEs are site-specific in that they integrate preferentially into a primary attachment site in the bacterial genome. Site-specific ICEs can also integrate into secondary locations, particularly if the primary site is absent. However, little is known about the consequences of integration of ICEs into alternative attachment sites or what drives the apparent maintenance and prevalence of the many ICEs that use a single attachment site. Using ICEBs1, a site-specific ICE from Bacillus subtilis that integrates into a tRNA gene, we found that integration into secondary sites was detrimental to both ICEBs1 and the host cell. Excision of ICEBs1 from secondary sites was impaired either partially or completely, limiting the spread of ICEBs1. Furthermore, induction of ICEBs1 gene expression caused a substantial drop in proliferation and cell viability within three hours. This drop was dependent on rolling circle replication of ICEBs1 that was unable to excise from the chromosome. Together, these detrimental effects provide selective pressure against the survival and dissemination of ICEs that have integrated into alternative sites and may explain the maintenance of site-specific integration for many ICEs.United States. Public Health Service (Grant GM050895

    Women's empowerment, production choices, and crop diversity in Burkina Faso, India, Malawi, and Tanzania: a secondary analysis of cross-sectional data

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    BACKGROUND: Bolstering farm-level crop diversity is one strategy to strengthen food system resilience and achieve global food security. Women who live in rural areas play an essential role in food production; therefore, we aimed to assess the associations between women's empowerment and crop diversity. METHODS: In this secondary analysis of cross-sectional data, we used data from four cluster-randomised controlled trials done in Burkina Faso, India, Malawi, and Tanzania. We assessed women's empowerment using indicators from the Women's Empowerment in Agriculture Index. Farm-level crop diversity measures were the number of food crops grown, number of food groups grown, and if nutrient-dense crops were grown. We used a two-stage modelling approach. First, we analysed covariate-adjusted country-specific associations between women's empowerment and crop diversity indicators using multivariable generalised linear models. Second, we pooled country-specific associations using random-effects models. FINDINGS: The final analytic sample included 1735 women from Burkina Faso, 4450 women from India, 547 women from Malawi, and 574 women from Tanzania. Across all countries, compared with households in which women provided input into fewer productive decisions, households of women with greater input into productive decisions produced more food crops (mean difference 0·36 [95% CI 0·16-0·55]), a higher number of food groups (mean difference 0·16 [0·06-0·25]), and more nutrient-dense crops (percentage point difference 3 [95% CI 3-4]). Across all countries, each additional community group a woman actively participated in was associated with cultivating a higher number of food crops (mean difference 0·20 [0·04-0·35]) and a higher number of food groups (mean difference 0·11 [0·03-0·18]), but not more nutrient-dense crops. In pooled associations from Burkina Faso and India, asset ownership was associated with cultivating a higher number of food crops (mean difference 0·08 [0·04-0·12]) and a higher number of food groups (mean difference 0·05 [0·04-0·07]), but not more nutrient-dense crops. INTERPRETATION: Greater women's empowerment was associated with higher farm-level crop diversity among low-income agricultural households, suggesting that it could help enhance efforts to strengthen food system resilience. FUNDING: Bill & Melinda Gates Foundation

    The Bright End of the UV Luminosity Function at z~8: New Constraints from CANDELS Data in GOODS-South

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    We present new z~8 galaxy candidates from a search over ~95 arcmin^2 of WFC3/IR data, tripling the previous search area for bright z~8 galaxies. Our analysis uses newly acquired WFC3/IR imaging data from the CANDELS Multi-Cycle Treasury program over the GOODS South field. These new data are combined with existing deep optical ACS imaging to search for relatively bright (M_UV < -19.5 mag) z~8 galaxy candidates using the Lyman Break technique. These new candidates are used to determine the bright end of the UV luminosity function (LF) of star-forming galaxies at z~8. To minimize contamination from lower redshift galaxies, we make full use of all optical ACS data and impose strict non-detection criteria based on an optical chi^2_opt flux measurement. In the whole search area we identify 16 candidate z~8 galaxies, spanning a magnitude range H_160 = 25.7-27.9 mag. The new data show that the UV LF is a factor ~1.7x lower at M_UV < -19.5 mag than determined from the HUDF09 and ERS data alone. Combining this new sample with the previous candidates from the HUDF09 and ERS data allows us to perform the most accurate measurement of the z~8 UV LF yet. Schechter function fits to the combined data result in a best-fit characteristic magnitude of M*(z=8) = -20.04+-0.46 mag. The faint-end slope is very steep, though quite uncertain, with alpha = -2.06+-0.32. A combination of wide area data with additional ultra-deep imaging will be required to significantly reduce the uncertainties on these parameters in the future.Comment: 16 pages, 12 figures; ApJ in pres

    Compensating control participants when the intervention is of significant value: experience in Guatemala, India, Peru and Rwanda

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    The Household Air Pollution Intervention Network (HAPIN) trial is a randomised controlled trial in Guatemala, India, Peru and Rwanda to assess the health impact of a clean cooking intervention in households using solid biomass for cooking. The HAPIN intervention—a liquefied petroleum gas (LPG) stove and 18-month supply of LPG—has significant value in these communities, irrespective of potential health benefits. For control households, it was necessary to develop a compensation strategy that would be comparable across four settings and would address concerns about differential loss to follow-up, fairness and potential effects on household economics. Each site developed slightly different, contextually appropriate compensation packages by combining a set of uniform principles with local community input. In Guatemala, control compensation consists of coupons equivalent to the LPG stove’s value that can be redeemed for the participant’s choice of household items, which could include an LPG stove. In Peru, control households receive several small items during the trial, plus the intervention stove and 1 month of fuel at the trial’s conclusion. Rwandan participants are given small items during the trial and a choice of a solar kit, LPG stove and four fuel refills, or cash equivalent at the end. India is the only setting in which control participants receive the intervention (LPG stove and 18 months of fuel) at the trial’s end while also being compensated for their time during the trial, in accordance with local ethics committee requirements. The approaches presented here could inform compensation strategy development in future multi-country trials

    The Transcriptional Regulator Rok Binds A+T-Rich DNA and Is Involved in Repression of a Mobile Genetic Element in Bacillus subtilis

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    The rok gene of Bacillus subtilis was identified as a negative regulator of competence development. It also controls expression of several genes not related to competence. We found that Rok binds to extended regions of the B. subtilis genome. These regions are characterized by a high A+T content and are known or believed to have been acquired by horizontal gene transfer. Some of the Rok binding regions are in known mobile genetic elements. A deletion of rok resulted in higher excision of one such element, ICEBs1, a conjugative transposon found integrated in the B. subtilis genome. When expressed in the Gram negative E. coli, Rok also associated with A+T-rich DNA and a conserved C-terminal region of Rok contributed to this association. Together with previous work, our findings indicate that Rok is a nucleoid associated protein that serves to help repress expression of A+T-rich genes, many of which appear to have been acquired by horizontal gene transfer. In these ways, Rok appears to be functionally analogous to H-NS, a nucleoid associated protein found in Gram negative bacteria and Lsr2 of high G+C Mycobacteria

    The epidemiological burden of obesity in childhood: a worldwide epidemic requiring urgent action

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    Background: In recent decades, the prevalence of obesity in children has increased dramatically. This worldwide epidemic has important consequences, including psychiatric, psychological and psychosocial disorders in childhood, and increased risk of developing noncommunicable diseases later in life. Treatment of obesity is difficult, and children with excess weight are likely to become adults with obesity. These trends have led World Health Organization (WHO) member states to endorse a target of no increase in obesity in childhood by 2025. Main body: Estimates of overweight in children aged under 5 years are available jointly from UNICEF, WHO and the World Bank. Country-level estimates of obesity in children aged from 2 to 4 years have been published by the Institute for Health Metrics and Evaluation (IHME). For children aged from 5 to 19, obesity estimates are available from the NCD Risk Factor Collaboration. The global prevalence of overweight in children aged under 5 years has increased modestly, but with heterogeneous trends in low- and middle-income regions, while the prevalence of obesity in children aged from 2 to 4 has increased moderately. For children aged 5 to 19, obesity was relatively rare in 1975, but was much more common in 2016. Conclusions: It is recognised that the key drivers of this epidemic form an obesogenic environment, which includes changing food systems and reduced physical activity. Although cost-effective interventions such as WHO “best buys” have been identified, political will and implementation have so far been limited. There is therefore a need to implement effective programmes and policies in multiple sectors to address overnutrition, undernutrition, mobility and physical activity. To be successful, the obesity epidemic must be a political priority, with these issues addressed both locally and globally. This must involve coordinated work by governments, civil society, private corporations and other key stakeholders
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