174 research outputs found

    Complex conductivity in strongly fluctuating layered superconductors

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    The time-dependent Ginzburg-Landau approach is used to calculate the complex fluctuation conductivity in layered type-II superconductor under magnetic field. Layered structure of the superconductor is accounted for by means of the Lawrence-Doniach model, while the nonlinear interaction term in dynamics is treated within self-consistent Gaussian approximation. In high-TcT_{c} materials, large portion of the HTH-T diagram belongs to vortex liquid phase. The expressions summing contributions of all the Landau levels are presented in explicit form which are applicable essentially to the whole phase and are compared to experimental data on high-TcT_{c} superconductor YBa2_{2}Cu3_{3}O7δ_{7-\delta }. Above the crossover to the "normal phase", our results agree with the previously obtained.Comment: 8 pages, 1 figur

    Two nonrecombining sympatric forms of the human malaria parasite Plasmodium ovale occur globally.

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    BACKGROUND: Malaria in humans is caused by apicomplexan parasites belonging to 5 species of the genus Plasmodium. Infections with Plasmodium ovale are widely distributed but rarely investigated, and the resulting burden of disease is not known. Dimorphism in defined genes has led to P. ovale parasites being divided into classic and variant types. We hypothesized that these dimorphs represent distinct parasite species. METHODS: Multilocus sequence analysis of 6 genetic characters was carried out among 55 isolates from 12 African and 3 Asia-Pacific countries. RESULTS: Each genetic character displayed complete dimorphism and segregated perfectly between the 2 types. Both types were identified in samples from Ghana, Nigeria, São Tomé, Sierra Leone, and Uganda and have been described previously in Myanmar. Splitting of the 2 lineages is estimated to have occurred between 1.0 and 3.5 million years ago in hominid hosts. CONCLUSIONS: We propose that P. ovale comprises 2 nonrecombining species that are sympatric in Africa and Asia. We speculate on possible scenarios that could have led to this speciation. Furthermore, the relatively high frequency of imported cases of symptomatic P. ovale infection in the United Kingdom suggests that the morbidity caused by ovale malaria has been underestimated

    The potential for REDD+ to reduce forest degradation in Vietnam

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    Natural forests in Vietnam have experienced rapid declines in the last 70 years, as a result of degradation from logging and conversion of natural forests to timber and rubber plantations. Degradation of natural forests leads to loss of biodiversity and ecosystem services, impacting the livelihoods of surrounding communities. Efforts to address ongoing loss of natural forests, through mechanisms such as Reduced Emissions from Deforestation and Degradation (REDD+), require an understanding of the links between forest degradation and the livelihoods of local communities, which have rarely been studied in Vietnam. We combined information from livelihood surveys, remote sensing and forest inventories around a protected natural forest area in North Central Vietnam. For forest-adjacent communities, we found natural forests contributed an average of 28% of total household income with plantation forests contributing an additional 15%. Although officially prohibited, logging contributed more than half of the total income derived from natural forests. Analysis of Landsat images over the period 1990 to 2014 combined with forest inventory data, demonstrates selective logging was leading to ongoing degradation of natural forests resulting in loss of 3.3±0.8 Mg biomass ha-1 yr-1 across the protected area. This is equivalent to 1.5% yr-1 of total forest biomass, with rates as high as 3% yr-1 in degraded and easily accessible parts of the protected area. We estimate that preventing illegal logging would incur local opportunity costs of USD $4.10±0.90 per Mg CO2, similar to previous estimates for tropical forest protected areas and substantially less than the opportunity costs in timber or agricultural concessions. Our analysis suggests activities to reduce forest degradation in protected areas are likely to be financially viable through Vietnam's REDD+ program

    The effects of time-restricted eating and weight loss on bone metabolism and health: a 6-month randomized controlled trial.

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    OBJECTIVE This study explored the impact of time-restricted eating (TRE) versus standard dietary advice (SDA) on bone health. METHODS Adults with ≥1 component of metabolic syndrome were randomized to TRE (ad libitum eating within 12 hours) or SDA (food pyramid brochure). Bone turnover markers and bone mineral content/density by dual energy x-ray absorptiometry were assessed at baseline and 6-month follow-up. Statistical analyses were performed in the total population and by weight loss response. RESULTS In the total population (n = 42, 76% women, median age 47 years [IQR: 31-52]), there were no between-group differences (TRE vs. SDA) in any bone parameter. Among weight loss responders (≥0.6 kg weight loss), the bone resorption marker β-carboxyterminal telopeptide of type I collagen tended to decrease after TRE but increase after SDA (between-group differences p = 0.041), whereas changes in the bone formation marker procollagen type I N-propeptide did not differ between groups. Total body bone mineral content decreased after SDA (p = 0.028) but remained unchanged after TRE (p = 0.31) in weight loss responders (between-group differences p = 0.028). Among nonresponders (<0.6 kg weight loss), there were no between-group differences in bone outcomes. CONCLUSIONS TRE had no detrimental impact on bone health, whereas, when weight loss occurred, it was associated with some bone-sparing effects compared with SDA

    Logging intensity drives variability in carbon stocks in lowland forests in Vietnam

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    Forest degradation in the tropics is generating large carbon (C) emissions. In tropical Asia, logging is the main driver of forest degradation. For effective implementation of REDD+ projects in logged forests in Southeast Asia, the impacts of logging on forest C stocks need to be assessed. Here, we assess C stocks in logged lowland forests in central Vietnam and explore correlations between logging intensity, soil, topography and living aboveground carbon (AGC) stocks. We present an approach to estimate historical logging intensities for the prevalent situation when complete records on logging history are unavailable. Landsat analysis and participatory mapping were used to quantify the density of historical disturbances, used as a proxy of logging intensities in the area. Carbon in AGC, dead wood, belowground carbon (BGC) and soil (SOC) was measured in twenty-four 0.25 ha plots that vary in logging intensity, and data on recent logging, soil properties, elevation and slope were also collected. Heavily logged forests stored only half the amount of AGC of stems ≥10 cm dbh as lightly logged forests, mainly due to a reduction in the number of large (≥60 cm dbh) trees. Carbon in AGC of small trees (5–10 cm dbh), dead wood and BGC comprised only small fractions of total C stocks, while SOC in the topsoil of 0–30 cm depth stored ~50% of total C stocks. Combining logging intensities with soil and topographic data showed that logging intensity was the main factor explaining the variability in AGC. Our research shows large reductions in AGC in medium and heavily logged forests. It highlights the critical importance of conserving big trees to maintain high forest C stocks and accounting for SOC in total C stock estimates

    Clinical Features of Dengue in a Large Vietnamese Cohort: Intrinsically Lower Platelet Counts and Greater Risk for Bleeding in Adults than Children

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    Dengue is a common and potentially serious viral illness. Complications include plasma leakage from small blood vessels causing shock and dysfunction of the systems that control blood clotting, resulting in bleeding. The disease used to affect children predominantly, but in recent years, the number of adult patients has been increasing. As there is limited data describing the patterns of complications by age, we performed this study to compare clinical and laboratory features, management, and outcomes of the disease for over 1,500 children and adults with confirmed dengue recruited at the same time at a single hospital in the Southern Vietnam. We found that plasma leakage and shock were more common and severe in children than adults, while bleeding and organ dysfunction were more frequent in adults. Adults had lower platelet counts throughout the illness course as well as at a follow-up visit several weeks after recovery. Platelets are a crucial element in controlling bleeding, and the intrinsically lower counts in adults compared to children may contribute to the greater risk for bleeding in this patient group. Knowledge about differences in the patterns of dengue-related complications between children and adults should help clinicians to diagnose and treat patients more effectively

    Long-Term Weekly Iron-Folic Acid and De-Worming Is Associated with Stabilised Haemoglobin and Increasing Iron Stores in Non-Pregnant Women in Vietnam

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    BACKGROUND: The prevalence of anaemia and iron deficiency in women remains high worldwide. WHO recommends weekly iron-folic acid supplementation where anaemia rates in non-pregnant women of reproductive age are higher than 20%. In 2006, a demonstration project consisting of weekly iron-folic acid supplementation and regular de-worming was set up in two districts in a northern province in Vietnam where anaemia and hookworm rates were 38% and 76% respectively. In 2008 the project was expanded to all districts in the province, targeting some 250,000 women. The objectives of this study were to: 1) examine changes in haemoglobin, iron stores and soil transmitted helminth infection prevalence over three years and 2) assess women's access to and compliance with the intervention. METHODS AND FINDINGS: The study was a semi-cross-sectional, semi-longitudinal panel design with a baseline survey, three impact surveys at three-, twelve- and thirty months after commencement of the intervention, and three compliance surveys after ten weeks, eighteen and thirty six months. RESULTS: After thirty months, mean haemoglobin stabilised at 130.3 g/L, an increase of 8.2 g/L from baseline, and mean serum ferritin rose from 23.9 µg/L to 52 µg/L. Hookworm prevalence fell from 76% to 22% over the same period. After thirty six months, 81% of the target population were receiving supplements and 87% were taking 75% or more of the supplements they received. CONCLUSIONS: Weekly iron-folic acid supplementation and regular de-worming was effective in significantly and sustainably reducing the prevalence of anaemia and soil transmitted helminth infections and high compliance rates were maintained over three years

    The Sleep/Wake Cycle is Directly Modulated by Changes in Energy Balance.

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    STUDY OBJECTIVES: The rise in obesity has been paralleled by a decline in sleep duration in epidemiological studies. However, the potential mechanisms linking energy balance and the sleep/wake cycle are not well understood. We aimed to examine the effects of manipulating energy balance on the sleep/wake cycle. METHODS: Twelve healthy normal weight men were housed in a clinical research facility and studied at three time points: baseline, after energy balance was disrupted by 2 days of caloric restriction to 10% of energy requirements, and after energy balance was restored by 2 days of ad libitum/free feeding. Sleep architecture, duration of sleep stages, and sleep-associated respiratory parameters were measured by polysomnography. RESULTS: Two days of caloric restriction significantly increased the duration of deep (stage 4) sleep (16.8% to 21.7% of total sleep time; P = 0.03); an effect which was entirely reversed upon free feeding (P = 0.01). Although the apnea-hypopnea index stayed within the reference range (< 5 events per hour), it decreased significantly from caloric restriction to free feeding (P = 0.03). Caloric restriction was associated with a marked fall in leptin (P < 0.001) and insulin levels (P = 0.002). The fall in orexin levels from baseline to caloric restriction correlated positively with duration of stage 4 sleep (Spearman rho = 0.83, P = 0.01) and negatively with the number of awakenings in caloric restriction (Spearman rho = -0.79, P = 0.01). CONCLUSIONS: We demonstrate that changes in energy homeostasis directly and reversibly impact on the sleep/wake cycle. These findings provide a mechanistic framework for investigating the association between sleep duration and obesity risk.Wellcome Trust, National Institute for Health Research Cambridge Biomedical Research Centre, European Research Council, Bernard Wolfe Health Neuroscience Fund, Swiss National Science Foundation (Grant IDs: PBLAP3-145870, P3SMP3-155318), European Society of Endocrinology (Grant ID: IESP), German Research Foundation (Grant ID: TR-SFB 654, B01), NeuroFAST consortium which is funded by the European Union’s Seventh Framework Programme (FP7/2007-2013) (Grant ID: 245009)This is the author accepted manuscript. The final version is available from the Associated Professional Sleep Societies, LLC via http://dx.doi.org/10.5665/sleep.609
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