Controlled MOCVD growth of Bi2Se3 topological insulator nanoribbons

Topological insulators are a new class of materials that support topologically protected electronic surface states. Potential applications of the surface states in low dissipation electronic devices have motivated efforts to create nanoscale samples with large surface-to-volume ratios and highly controlled stoichiometry. Se vacancies in Bi2Se3 give rise to bulk conduction, which masks the transport properties of the surface states. We have therefore developed a new route for the synthesis of topological insulator nanostructures using metalorganic chemical vapour deposition (MOCVD). MOCVD allows for control of the Se/Bi flux ratio during growth. With the aim of rational growth, we vary the Se/Bi flux ratio, growth time, and substrate temperature, and observe morphological changes which indicate a growth regime in which nanoribbon formation is limited by the Bi precursor mass-flow. MOCVD growth of Bi2Se3 nanostructures occurs via a distinct growth mechanism that is nucleated by gold nanoparticles at the base of the nanowire. By tuning the reaction conditions, we obtain either single-crystalline ribbons up to 10 microns long or thin micron-sized platelets.Comment: Related papers at http://pettagroup.princeton.ed

Accounting for cryptic population substructure enhances detection of inbreeding depression with genomic inbreeding coefficients: an example from a critically endangered marsupial

Characterizing inbreeding depression in wildlife populations can be critical to their conservation. Coefficients of individual inbreeding can be estimated from genome-wide marker data. The degree to which sensitivity of inbreeding coefficients to population genetic substructure alters estimates of inbreeding depression in wild populations is not well understood. Using generalized linear models, we tested the power of two frequently used inbreeding coefficients that are calculated from genome-wide SNP markers, FH and F^III, to predict four fitness traits estimated over two decades in an isolated population of the critically endangered Leadbeater's possum. FH estimates inbreeding as excess observed homozygotes relative to equilibrium expectations, whereas F^III quantifies allelic similarity between the gametes that formed an individual, and upweights rare homozygotes. We estimated FH and F^III from 1,575 genome-wide SNP loci in individuals with fitness trait data (N = 179–237 per trait), and computed revised coefficients, FHby group and F^IIIby group, adjusted for population genetic substructure by calculating them separately within two different genetic groups of individuals identified in the population. Using FH or F^III in the models, inbreeding depression was detected for survival to sexual maturity, longevity and whether individuals bred during their lifetime. F^IIIby group (but not FHby group) additionally revealed significant inbreeding depression for lifetime reproductive output (total offspring assigned to each individual). Estimates of numbers of lethal equivalents indicated substantial inbreeding load, but differing between inbreeding estimators. Inbreeding depression, declining population size, and low and declining genetic diversity suggest that genetic rescue may assist in preventing extinction of this unique Leadbeater's possum population. © 2020 John Wiley & Sons Lt

Reconfigurable binary optical routing switches with fan-out based on the integration of GaAs/AlGaAs surface-emitting lasers and heterojunction phototransistors

Includes bibliographical references.The design, fabrication, and experimental demonstration of dynamically reconfigurable binary optical switches based on the integration of GaAs/AlGaAs vertical-cavity surface-emitting lasers and heterojunction phototransistors are reported. These new monolithic optical switches can perform spatial routing and optical amplification functions on input optical data with a fan-out of two, and can be programmed using simple voltage control. The 1 × 2 and 2 × 2 devices provide the basis for a high performance, two-dimensional optical switching fabric with electrical interfaces for optical switching and interconnection networks.The work at UNM was supported by Rome Laboratories (Griffiss AFB), the Advanced Research Projects Agency-MTO, and the Air Force Office of Scientific Research (Bolling AFB). The work performed at Sandia was supported by DOE Contract No. DE-AC04-76DP00789

Binary optical switch and programmable optical logic gate based on the integration of GaAs/AlGaAs surface-emitting lasers and heterojunction phototransistors

Includes bibliographical references.Optical switches based on GaAs/AlGaAs vertical-cavity surface-emitting lasers and heterojunction phototransistors are combined monolithically into new switching configurations that perform optical logic and spatial routing in a dynamically programmable manner. Using simple voltage control, many different logic and routing configurations, including AND and OR gates with variable fan-out, can be implemented using the same hardware.The work at UNM was supported by AFOSR (Bolling AFB), ARPA, and Rome Labs (Griffiss AFB). The Sandia effort was supported by DOE Contract No. DE-AC04-94AL85000

Вплив “ЕМ® ПРОБІОТИК для БДЖІЛ” на динаміку тривалості життя бджіл в садковому досліді

At present, Ukraine is one of the first honey producing country in Europe. Around 100 thousand tonnes of honey are produced annually in Ukraine, therefore, maintaining the health of the bee colonies is an important issue. The use of different groups of drugs for the prevention of bee diseases is strictly controlled, now the known alternatives to antibiotics are probiotics. The micro-organisms in these preparats are able to synthesise vitamins and amino acids necessary for the growth and development of bees, which in turn activates the immunocompetent cells of the insects and prolongs their life. The immunomodulatory and immunostimulatory ability of such supplements of “beneficial” microorganisms is known, both in veterinary and human medicine. The use of such remedies is therefore promising in the field of modern beekeeping. “EM® PROBIOTIC FOR BEES” is a biopreparation that positively influences the microbiological environment of insects, as the preparation is based on Effective Microorganisms®. The ability of this probiotic to influence the dynamics of life span of Ukrainian steppe bees in a wooden entomological cage experiment (in vivo) was the main objective of the experiment. The effect of the probiotic on bee viability was determined by daily analysis and counting the number of dead insects. The study involved the settlement of bees in a wooden entomological cages and the creation of optimal conditions for their keeping (at a temperature of +24 – +25 °C and a humidity of 50–70 %). The product was diluted with buckwheat honey syrup solution and sugar syrup solution at concentrations of 5 %; 2.5 %; 1.25 %; control groups of bees received native solutions of the sugar syrup and buckwheat honey syrup. The analysis of the results shows a positive effect of “EM® PROBIOTIC FOR BEES” on the longevity of Ukrainian steppe worker bees of the winter generation in a entomological cage experiment. A beneficial effect of the probiotic product diluted in sugar syrup at concentrations of 1.25 % to 5 % has been detected on the bee organism, which increased their lifespan. When the product was diluted with buckwheat honey syrup, the best longevity of the insects was recorded at a concentration of 1.25 % compared to the control group of bees. The coefficient of average life expectancy of bees indicates the predominance of sugar syrup as a solvent for this probiotic compared to buckwheat honey syrup under laboratory conditions.На теперішній час Україна займає одне з перших місць з виробництва меду серед країн Європи. Щороку близько 100 тис. тонн меду виробляється в Україні, тому важливим питанням є підтримка здоров’я бджолосімей у належному стані. Використання різних груп препаратів для профілактики хвороб бджіл строго контролюється, наразі відомими альтернативними засобами до антибіотиків є пробіотики. Мікроорганізми, що входять до складу таких засобів, здатні синтезувати низку вітамінів та амінокислот, необхідних для росту та розвитку бджіл, що своєю чергою призводить до активації імунокомпетентних клітин організму комах, що сприяє продовженню тривалості їхнього життя. Імуномодулююча та імуностимулююча здатність таких добавок «корисних» мікроорганізмів відома як у ветеринарній, так і в гуманній медицині. Тому використання таких засобів є перспективним у галузі сучасного бджільництва. “ЕМ® ПРОБІОТИК для БДЖІЛ” – біопрепарат, який позитивно впливає на мікробіологічне середовище комах, оскільки виготовлений на основі Ефективних Мікроорганізмів®. Здатність до впливу даного пробіотика на динаміку тривалості життя бджіл української степової породи в садковому експерименті (in vivo) було основною метою експерименту. Вплив пробіотика на життєздатність бджіл визначали шляхом щоденного аналізу і підрахунку кількості загиблих комах. Дослідження включало поселення бджіл у ентомологічні садки та створення оптимальних умов їх утримання (при температурі +24–+25 ºС і вологості повітря 50–70 %). Препарат розводили медовою гречаною ситою та розчином цукрового сиропу у концентраціях 5 %; 2,5 %; 1,25 %; контрольні групи бджіл отримувати нативні розчини цукрового сиропу та гречаної медової сити. Аналіз отриманих результатів свідчить про позитивний вплив “ЕМ® ПРОБІОТИКа для БДЖІЛ” на тривалість життя робочих бджіл української степової породи, зимової генерації, у садковому досліді. Зареєстровано сприятливу дію пробіотичного препарату, розведеного цукровим сиропом у концентраціях 1,25–5 % на бджолиний організм, що сприяє збільшенню тривалості їхнього життя. При розведенні препарату медовою гречаною ситою найдовша тривалість життя комах зареєстрована при концентрації 1,25 % порівняно із контрольною групою бджіл. Коефіцієнт середньої тривалості життя бджіл свідчить про перевагу цукрового сиропу як розчинника для даного пробіотика порівняно з гречаною медовою ситою в лабораторних умовах

Getting under the skin: children's health disparities as embodiment of social class

Social class gradients in children’s health and development are ubiquitous across time and geography. The authors develop a conceptual framework relating three actions of class—material allocation, salient group identity, and inter-group conflict—to the reproduction of class-based disparities in child health. A core proposition is that the actions of class stratification create variation in children’s mesosystems and microsystems in distinct locations in the ecology of everyday life. Variation in mesosystems (e.g., health care, neighborhoods) and microsystems (e.g., family structure, housing) become manifest in a wide variety of specific experiences and environments that produce the behavioral and biological antecedents to health and disease among children. The framework is explored via a review of theoretical and empirical contributions from multiple disciplines and high-priority areas for future research are highlighted

Pre-pregnancy body mass index and gestational weight gain and their effects on pregnancy and birth outcomes: a cohort study in West Sumatra, Indonesia

Background: Indonesia has a considerably high incidence of maternal and infant mortality. The country has however been experiencing a social and economic transition, influencing its general population demographics and nutritional status including the state of health and nutrition of pregnant women. This study aimed to explore body mass index (BMI) and gestational weight gain (GWG), and their relationship with pregnancy outcomes in a sample of Indonesian pregnant women. Methods: This observational cohort study included a total of 607 pregnant women who were recruited in 2010 from maternity clinics in Western Sumatra, Indonesia. Multiple logistic and regression analyses were undertaken to compare pregnancy and birth outcomes for different BMI and GWG, using normal weight women and women with a recommended weight gain as the referent groups. Results: The prevalence of underweight (BMI < 18.5 kg/m2) in pregnancy was high at 20.1%; while 21.7% of women were overweight (BMI: 23.0–27.4 kg/m2) and 5.3% obese (BMI ≥ 27.5 kg/m2) using the Asian BMI classifications. The incidence of overweight (BMI: 25.0–29.9 kg/m2) and obese (BMI ≥ 30.0 kg/m2) according to the international BMI classifications were 13.5% and 1.1% respectively. The majority of women gained inadequate weight in pregnancy compared to the Institute of Medicine (IOM)recommendations, especially those who had a normal BMI. Birthweight adjusted mean difference aMD (95% confidence interval) 205 (46,365) and the odds of macrosomia adjusted odds ratio aOR 13.46 (2.32–77.99) significantly increased in obese women compared to those with a normal BMI. Birthweight aMD -139 (−215, −64) significantly decreased in women with inadequate GWG compared to those with recommended GWG, while SGA aOR 5.44 (1.36, 21.77) and prematurity aOR 3.55 (1.23, 10.21) increased. Conclusions: Low nutritional status and inadequate GWG remain a cause for concern in these women. The higher odds of macrosomia with increasing maternal BMI and higher odds of prematurity and small for gestational age infants with inadequate weight gain also require attention. Research and practice recommendations: Urgent attention is required by researchers, policy makers and decision makers to facilitate development of culturally sensitive interventions to enhance nutritional status and health of mothers and babies, in an area known for its high incidence of maternal and neonatal mortality. Keywords: Maternal BMI, Gestational weight gain, Pregnancy outcomes, Birthweight, Indonesia, Cohort stud

Gestational Weight Gain and Body Mass Index in Children: Results from Three German Cohort Studies

Previous studies suggested potential priming effects of gestational weight gain (GWG) on offspring's body composition in later life. However, consistency of these effects in normal weight, overweight and obese mothers is less clear. We combined the individual data of three German cohorts and assessed associations of total and excessive GWG (as defined by criteria of the Institute of Medicine) with offspring's mean body mass index (BMI) standard deviation scores (SDS) and overweight at the age of 5-6 years (total: n = 6,254). Quantile regression was used to examine potentially different effects on different parts of the BMI SDS distribution. All models were adjusted for birth weight, maternal age and maternal smoking during pregnancy and stratified by maternal pre-pregnancy weight status. In adjusted models, positive associations of total and excessive GWG with mean BMI SDS and overweight were observed only in children of non- overweight mothers. For example, excessive GWG was associated with a mean increase of 0.08 (95% CI: 0.01, 0.15) units of BMI SDS (0.13 (0.02, 0.24) kg/m(2) of 'real' BMI) in children of normal-weight mothers. The effects of total and excessive GWG on BMI SDS increased for higher- BMI children of normal-weight mothers. Increased GWG is likely to be associated with overweight in offspring of non-overweight mothers

Obesity and Weight Gain in Pregnancy and Postpartum: An Evidence Review of Lifestyle Interventions to Inform Maternal and Child Health Policies

Background: Maternal obesity, excessive gestational weight gain (GWG) and post-partum weight retention (PPWR) constitute new public health challenges, due to the association with negative short- and long-term maternal and neonatal outcomes. The aim of this evidence review was to identify effective lifestyle interventions to manage weight and improve maternal and infant outcomes during pregnancy and postpartum. Methods: A review of systematic reviews and meta-analyses investigating the effects of lifestyle interventions on GWG or PPWR was conducted (Jan 2009-2018) via electronic searches in the databases Medline, Pubmed, Web of Science and Cochrane Library using all keywords related to obesity/weight gain/loss, pregnancy or postpartum and lifestyle interventions;15 relevant reviews were selected. Results: In healthy women from all BMI classes, diet and physical activity interventions can decrease: GWG (mean difference -1.8 to -0.7 kg, high to moderate-quality evidence); the risks of GWG above the IOM guidelines (risk ratio [RR] 0.72 to 0.80, high to low-quality evidence); pregnancy-induced hypertension (RR 0.30 to 0.66, low to very low-quality evidence); cesarean section (RR 0.91 to 0.95; high to moderate-quality evidence) and neonatal respiratory distress syndrome (RR 0.56, high-quality evidence); without any maternal/fetal/neonatal adverse effects. In women with overweight/obesity, multi-component interventions can decrease: GWG (-0.91 to -0.63 kg, moderate to very low-quality evidence); pregnancy-induced hypertension (RR 0.30 to 0.66, low-quality evidence); macrosomia (RR 0.85, 0.73 to 1.0, moderate-quality evidence) and neonatal respiratory distress syndrome (RR 0.47, 0.26 to 0.85, moderate-quality evidence). Diet is associated with greater reduction of the risks of GDM, pregnancy-induced hypertension and preterm birth, compared with any other intervention. After delivery, combined diet and physical activity interventions reduce PPWR in women of any BMI (-2.57 to -2.3 kg, very low quality evidence) or with overweight/obesity (-3.6 to -1.22, moderate to very low-quality-evidence), but no other effects were reported. Conclusions: Multi-component approaches including a balanced diet with low glycaemic load and light to moderate intensity physical activity, 30-60 min per day 3-5 days per week, should be recommended from the first trimester of pregnancy and maintained during the postpartum period. This evidence review should help inform recommendations for health care professionals and women of child-bearing age