2,952 research outputs found
Sources of origin and meteorological importance of hygroscopic and iceforming nuclei
The hygroscopic nuclei whose source region during the monsoon is the sea penetrate far into the interior and play important role in development of precipitation well inland. The fraction of such nuclei present in the total aerosol constitutes a more dependable criterion for distinguishing maritime airmasses from those of others. Development of rain frequently by all-water and ice-crystal mechanisms have been suggested by the large concentrations noticed of the hygroscopic and ice-forming aerosols respectively. While it is seen that there is a major identifiable singular source, which is the sea, for hygroscopic aerosols at Delhi, it does not appear to be so in the case of ice-forming nuclei. The latter are of varied origin and might be maritime, continental, stratospheric etc
Boundary-layer effects on acoustic transmission through narrow slit cavities
PublishedJournal ArticleWe explore the slit-width dependence of the resonant transmission of sound in air through both a slit array formed of aluminum slats and a single open-ended slit cavity in an aluminum plate. Our experimental results accord well with Lord Rayleigh's theory concerning how thin viscous and thermal boundary layers at a slit's walls affect the acoustic wave across the whole slit cavity. By measuring accurately the frequencies of the Fabry-Perot-like cavity resonances, we find a significant 5% reduction in the effective speed of sound through the slits when an individual viscous boundary layer occupies only 5% of the total slit width. Importantly, this effect is true for any airborne slit cavity, with the reduction being achieved despite the slit width being on a far larger scale than an individual boundary layer's thickness. This work demonstrates that the recent prevalent loss-free treatment of narrow slit cavities within acoustic metamaterials is unrealistic.The authors would like to thank DSTL for their financial support
Primary Ovarian Insufficiency: Current Understanding and Diagnostic Approaches
Primary ovarian insufficiency (POI) is a medical condition where ovarian function stops prematurely, typically before the age of 40. This condition leads to infertility and produces symptoms similar to those experienced during menopause. Although the origins of POIs are diverse, genetic elements substantially influence their emergence. This assessment delves into the genetic facets of POI, covering genetic triggers, detection, and genetic consultation. We scrutinize the genes linked to POI and their function in ovarian activity, as well as the genetic deviations and mutations that foster POI onset. We also examine the challenges and limitations of genetic testing and counseling for POI and suggest ways to address these challenges. This review offers a thorough examination of the existing understanding of the genetic factors linked to Primary Ovarian Insufficiency (POI) emphasizing the critical need for further investigation in this field
Effects of participatory learning and action with women's groups, counselling through home visits and crèches on undernutrition among children under three years in eastern India: a quasi-experimental study
BACKGROUND: India faces a high burden of child undernutrition. We evaluated the effects of two community strategies to reduce undernutrition among children under 3 years in rural Jharkhand and Odisha, eastern India: (1) monthly Participatory Learning and Action (PLA) meetings with women's groups followed by home visits; (2) crèches for children aged 6 months to 3 years combined with monthly PLA meetings and home visits. METHODS: We tested these strategies in a non-randomised, controlled study with baseline and endline cross-sectional surveys. We purposively selected five blocks of Jharkhand and Odisha, and divided each block into three areas. Area 1 served as control. In Area 2, trained local female workers facilitated PLA meetings and offered counselling to mothers of children under three at home. In Area 3, workers facilitated PLA meetings, did home visits, and crèches with food and growth monitoring were opened for children aged 6 months to 3 years. We did a census across all study areas and randomly sampled 4668 children under three and their mothers for interview and anthropometry at baseline and endline. The evaluation's primary outcome was wasting among children under three in areas 2 and 3 compared with area 1, adjusted for baseline differences between areas. Other outcomes included underweight, stunting, preventive and care-seeking practices for children. RESULTS: We interviewed 83% (3868/4668) of mothers of children under three sampled at baseline, and 76% (3563/4668) at endline. In area 2 (PLA and home visits), wasting among children under three was reduced by 34% (adjusted Odds Ratio [aOR]: 0.66, 95%: 0.51-0.88) and underweight by 25% (aOR: 0.75, 95% CI: 0.59-0.95), with no change in stunting (aOR: 1.23, 95% CI: 0.96-1.57). In area 3, (PLA, home visits, crèches), wasting was reduced by 27% (aOR: 0.73, 95% CI: 0.55-0.97), underweight by 40% (aOR: 0.60, 95% CI: 0.47-0.75), and stunting by 27% (aOR: 0.73, 95% CI: 0.57-0.93). CONCLUSIONS: Crèches, PLA meetings and home visits reduced undernutrition among children under three in rural eastern India. These interventions could be scaled up through government plans to strengthen home visits and community mobilisation with Accredited Social Health Activists, and through efforts to promote crèches. TRIAL REGISTRATION: The evaluation was registered retrospectively with Current Controlled Trials as ISCRTN89911047 on 30/01/2019
Unraveling the mysteries of dog evolution
The increased battery of molecular markers, derived from comparative genomics, is aiding our understanding of the genetics of domestication. The recent BMC Biology article pertaining to the evolution of small size in dogs is an example of how such methods can be used to study the origin and diversification of the domestic dog. We are still challenged, however, to appreciate the genetic mechanisms responsible for the phenotypic diversity seen in 'our best friend'
Deep sequencing of HIV-1 reveals extensive subtype variation and drug resistance after failure of first-line antiretroviral regimens in Nigeria
BACKGROUND: Deep sequencing could improve understanding of HIV treatment failure and viral population dynamics. However, this tool is often inaccessible in low- and middle-income countries. OBJECTIVES: To determine the genetic patterns of resistance emerging in West African HIV-1 subtypes during first-line virological failure, and the implications for future antiretroviral options. PATIENTS AND METHODS: Participants were selected from a Nigerian cohort of people living with HIV who had failed first-line ART and subsequently switched to second-line therapy. Whole HIV-1 genome sequences were generated from first-line virological failure samples with Illumina MiSeq. Mutations detected at âĽ2% frequency were analysed and compared by subtype. RESULTS: HIV-1 sequences were obtained from 101 participants (65% female, median age 30 years, median 32.9 months of nevirapine- or efavirenz-based ART). Thymidine analogue mutations (TAMs) were detected in 61%, other core NRTI mutations in 92% and NNRTI mutations in 99%. Minority variants (<20% frequency) comprised 18% of all mutations. K65R was more prevalent in CRF02_AG than G subtypes (33% versus 7%; Pâ=â0.002), and âĽ3 TAMs were more common in G than CRF02_AG (52% versus 24%; Pâ=â0.004). Subtype G viruses also contained more RT cleavage site mutations. Cross-resistance to at least one of the newer NNRTIs, doravirine, etravirine or rilpivirine, was predicted in 81% of participants. CONCLUSIONS: Extensive drug resistance had accumulated in people with West African HIV-1 subtypes, prior to second-line ART. Deep sequencing significantly increased the detection of resistance-associated mutations. Caution should be used if considering newer-generation NNRTI agents in this setting
Characterising the incidence and mode of visceral stent failure after fenestrated endovascular aneurysm repair (FEVAR)
Background
In FEVAR, visceral stents provide continuity and maintain perfusion between the main body of the stent and the respective visceral artery. The aim of this study was to characterise the incidence and mode of visceral stent failure (type Ic endoleak, type IIIa endoleak, stenosis/kink, fracture, crush and occlusion) after FEVAR in a large cohort of patients at a high-volume centre.
Methods
A retrospective review of visceral stents placed during FEVAR over 15 years (February 2003-December 2018) was performed. Kaplan-Meier analyses of freedom from visceral stent-related complications were performed. The outcomes between graft configurations of varying complexity were compared, as were the outcomes of different stent types and different visceral vessels.
Results
Visceral stent complications occurred in 47/236 patients (19.9%) and 54/653 stents (8.3%). Median follow up was 3.7 years (IQR 1.7â5.3 years). There was no difference in visceral stent complication rate between renal, SMA and coeliac arteries. Visceral stent complications were more frequent in more complex grafts compared to less complex grafts. Visceral stent complications were more frequent in uncovered stents compared to covered stents. Visceral stent-related endoleaks (type Ic and type IIIa) occurred exclusively around renal artery stents. The most common modes of failure with SMA stents were kinking and fracture, whereas with coeliac artery stents it was external crush.
Conclusion
Visceral stent complications after FEVAR are common and merit continued and close long-term surveillance. The mode of visceral stent failure varies across the vessels in which the stents are located
High-density information storage in an absolutely defined aperiodic sequence of monodisperse copolyester
Synthesis of a polymer composed of a large discrete number of chemically distinct monomers in an absolutely defined aperiodic sequence remains a challenge in polymer chemistry. The synthesis has largely been limited to oligomers having a limited number of repeating units due to the difficulties associated with the step-by-step addition of individual monomers to achieve high molecular weights. Here we report the copolymers of ??-hydroxy acids, poly(phenyllactic-co-lactic acid) (PcL) built via the cross-convergent method from four dyads of monomers as constituent units. Our proposed method allows scalable synthesis of sequence-defined PcL in a minimal number of coupling steps from reagents in stoichiometric amounts. Digital information can be stored in an aperiodic sequence of PcL, which can be fully retrieved as binary code by mass spectrometry sequencing. The information storage density (bit/Da) of PcL is 50% higher than DNA, and the storage capacity of PcL can also be increased by adjusting the molecular weight (~38???kDa)
Harnessing Polyhydroxyalkanoates and Pressurized Gyration for Hard and Soft Tissue Engineering
Organ dysfunction is a major cause of morbidity and mortality. Transplantation is typically the only definitive cure, challenged by the lack of sufficient donor organs. Tissue engineering encompasses the development of biomaterial scaffolds to support cell attachment, proliferation, and differentiation, leading to tissue regeneration. For efficient clinical translation, the forming technology utilized must be suitable for mass production. Herein, uniaxial polyhydroxyalkanoate scaffolds manufactured by pressurized gyration, a hybrid scalable spinning technique, are successfully used in bone, nerve, and cardiovascular applications. Chorioallantoic membrane and in vivo studies provided evidence of vascularization, collagen deposition, and cellular invasion for bone tissue engineering. Highly efficient axonal outgrowth was observed in dorsal root ganglion-based 3D ex vivo models. Human induced pluripotent stem cell derived cardiomyocytes exhibited a mature cardiomyocyte phenotype with optimal calcium handling. This study confirms that engineered polyhydroxyalkanoate-based gyrospun fibers provide an exciting and unique toolbox for the development of scalable scaffolds for both hard and soft tissue regeneration
Effect of participatory women's groups facilitated by Accredited Social Health Activists on birth outcomes in rural eastern India: a cluster-randomised controlled trial
BACKGROUND: A quarter of the world's neonatal deaths and 15% of maternal deaths happen in India. Few community-based strategies to improve maternal and newborn health have been tested through the country's government-approved Accredited Social Health Activists (ASHAs). We aimed to test the effect of participatory women's groups facilitated by ASHAs on birth outcomes, including neonatal mortality. METHODS: In this cluster-randomised controlled trial of a community intervention to improve maternal and newborn health, we randomly assigned (1:1) geographical clusters in rural Jharkhand and Odisha, eastern India to intervention (participatory women's groups) or control (no women's groups). Study participants were women of reproductive age (15-49 years) who gave birth between Sept 1, 2009, and Dec 31, 2012. In the intervention group, ASHAs supported women's groups through a participatory learning and action meeting cycle. Groups discussed and prioritised maternal and newborn health problems, identified strategies to address them, implemented the strategies, and assessed their progress. We identified births, stillbirths, and neonatal deaths, and interviewed mothers 6 weeks after delivery. The primary outcome was neonatal mortality over a 2 year follow up. Analyses were by intention to treat. This trial is registered with ISRCTN, number ISRCTN31567106. FINDINGS: Between September, 2009, and December, 2012, we randomly assigned 30 clusters (estimated population 156â519) to intervention (15 clusters, estimated population n=82â702) or control (15 clusters, n=73â817). During the follow-up period (Jan 1, 2011, to Dec 31, 2012), we identified 3700 births in the intervention group and 3519 in the control group. One intervention cluster was lost to follow up. The neonatal mortality rate during this period was 30 per 1000 livebirths in the intervention group and 44 per 1000 livebirths in the control group (odds ratio [OR] 0.69, 95% CI 0¡53-0¡89). INTERPRETATION: ASHAs can successfully reduce neonatal mortality through participatory meetings with women's groups. This is a scalable community-based approach to improving neonatal survival in rural, underserved areas of India. FUNDING: Big Lottery Fund (UK)
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