1,284 research outputs found

    Hydrogen-poor superluminous stellar explosions

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    Supernovae (SNe) are stellar explosions driven by gravitational or thermonuclear energy, observed as electromagnetic radiation emitted over weeks or more. In all known SNe, this radiation comes from internal energy deposited in the outflowing ejecta by either radioactive decay of freshly-synthesized elements (typically 56Ni), stored heat deposited by the explosion shock in the envelope of a supergiant star, or interaction between the SN debris and slowly-moving, hydrogen-rich circumstellar material. Here we report on a new class of luminous SNe whose observed properties cannot be explained by any of these known processes. These include four new SNe we have discovered, and two previously unexplained events (SN 2005ap; SCP 06F6) that we can now identify as members. These SNe are all ~10 times brighter than SNe Ia, do not show any trace of hydrogen, emit significant ultra-violet (UV) flux for extended periods of time, and have late-time decay rates which are inconsistent with radioactivity. Our data require that the observed radiation is emitted by hydrogen-free material distributed over a large radius (~10^15 cm) and expanding at high velocities (>10^4 km s^-1). These long-lived, UV-luminous events can be observed out to redshifts z>4 and offer an excellent opportunity to study star formation in, and the interstellar medium of, primitive distant galaxies.Comment: Accepted to Nature. Press embargoed until 2011 June 8, 18:00 U

    Trends in long-term opioid prescribing in primary care patients with musculoskeletal conditions: an observational database study

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    Long-term opioids may benefit patients with chronic pain but have also been linked to harmful outcomes. In the United Kingdom, the predominant source of opioids is primary care prescription. The objective was to examine changes in the incidence, length, and opioid potency of long-term prescribing episodes for musculoskeletal conditions in UK primary care (2002-2013). This was an observational database study (Clinical Practice Research Datalink, 190 practices). Participants (≥18 years) were prescribed an opioid for a musculoskeletal condition (no opioid prescribed in previous 6 months), and issued ≥2 opioid prescriptions within 90 days (long-term episode). Opioids were divided into short- and long-acting noncontrolled and controlled drugs. Annual incidence of long-term opioid episodes was determined, and for those still in a long-term episode, the percentage of patients prescribed each type 1 to 2 years, and >2 years after initiation. Annual denominator population varied from 1.25 to 1.38 m. A total of 76,416 patients started 1 long-term episode. Annual long-term episode incidence increased (2002-2009) by 38% (42.4-58.3 per 10,000 person-years), remaining stable to 2011, then decreasing slightly to 55.8/10,000 (2013). Patients prescribed long-acting controlled opioids within the first 90 days of long-term use increased from 2002 to 2013 (2.3%-9.9%). In those still in a long-term opioid episode (>2 years), long-acting controlled opioid prescribing increased from 3.5% to 22.6%. This study has uniquely shown an increase in prescribing long-term opioids to 2009, gradually decreasing from 2011 in the United Kingdom. The trend was towards increased prescribing of controlled long-acting opioids and earlier use. Further research into the risks and benefits of opioids is required

    KDM6A/UTX promotes spermatogenic gene expression across generations and is not required for male fertility

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    Paternal chromatin undergoes extensive structural and epigenetic changes during mammalian spermatogenesis, producing sperm with an epigenome optimized for the transition to embryogenesis. Lysine demethylase 6a (KDM6A, also called UTX) promotes gene activation in part via demethylation of H3K27me3, a developmentally important repressive modification abundant throughout the epigenome of spermatogenic cells and sperm. We previously demonstrated increased cancer risk in genetically wild-type mice derived from a paternal germ line lacking Kdm6a (Kdm6a cKO), indicating a role for KDM6A in regulating heritable epigenetic states. However, the regulatory function of KDM6A during spermatogenesis is not known. Here, we show that Kdm6a is transiently expressed in spermatogenesis, with RNA and protein expression largely limited to late spermatogonia and early meiotic prophase. Kdm6a cKO males do not have defects in fertility or the overall progression of spermatogenesis. However, hundreds of genes are deregulated upon loss of Kdm6a in spermatogenic cells, with a strong bias toward downregulation coinciding with the time when Kdm6a is expressed. Misregulated genes encode factors involved in chromatin organization and regulation of repetitive elements, and a subset of these genes was persistently deregulated in the male germ line across two generations of offspring of Kdm6a cKO males. Genome-wide epigenetic profiling revealed broadening of H3K27me3 peaks in differentiating spermatogonia of Kdm6a cKO mice, suggesting that KDM6A demarcates H3K27me3 domains in the male germ line. Our findings highlight KDM6A as a transcriptional activator in the mammalian male germ line that is dispensable for spermatogenesis but important for safeguarding gene regulatory state intergenerationally

    Inhibition of Y1 receptor signaling improves islet transplant outcome

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    Failure to secrete sufficient quantities of insulin is a pathological feature of type-1 and type-2 diabetes, and also reduces the success of islet cell transplantation. Here we demonstrate that Y1 receptor signaling inhibits insulin release in β-cells, and show that this can be pharmacologically exploited to boost insulin secretion. Transplanting islets with Y1 receptor deficiency accelerates the normalization of hyperglycemia in chemically induced diabetic recipient mice, which can also be achieved by short-term pharmacological blockade of Y1 receptors in transplanted mouse and human islets. Furthermore, treatment of non-obese diabetic mice with a Y1 receptor antagonist delays the onset of diabetes. Mechanistically, Y1 receptor signaling inhibits the production of cAMP in islets, which via CREB mediated pathways results in the down-regulation of several key enzymes in glycolysis and ATP production. Thus, manipulating Y1 receptor signaling in β-cells offers a unique therapeutic opportunity for correcting insulin deficiency as it occurs in the pathological state of type-1 diabetes as well as during islet transplantation.Islet transplantation is considered one of the potential treatments for T1DM but limited islet survival and their impaired function pose limitations to this approach. Here Loh et al. show that the Y1 receptor is expressed in β- cells and inhibition of its signalling, both genetic and pharmacological, improves mouse and human islet function.info:eu-repo/semantics/publishe

    Rethinking drug design in the artificial intelligence era

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    Artificial intelligence (AI) tools are increasingly being applied in drug discovery. While some protagonists point to vast opportunities potentially offered by such tools, others remain sceptical, waiting for a clear impact to be shown in drug discovery projects. The reality is probably somewhere in-between these extremes, yet it is clear that AI is providing new challenges not only for the scientists involved but also for the biopharma industry and its established processes for discovering and developing new medicines. This article presents the views of a diverse group of international experts on the 'grand challenges' in small-molecule drug discovery with AI and the approaches to address them

    The influence of farmers' mental models on an agroforestry extension program in the Philippines

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    The influence of farmers' mental models on the success of an agroforestry extension program on Leyte Island in the Philippines was investigated. Knowledge of farmers' mental models and hence the likely acceptance of technology was used to inform the design of a hypothetically expanded program. To gain an insight into the reasons behind differing acceptance of extension assistance, data were collected and analysed from formal interviews, translated conversations and visual observations. The data provided a chain of evidence and triangulation between farmers' stated intentions and their actions. Farmers had little prior knowledge of nursery technology and were highly receptive to extension assistance which enabled them to develop high self-efficacy in seedling production. However, farmers' rejection of silvicultural advice to thin and prune existing plantations was predicated by existing attitudes to forest resource management. Farmers also expressed a strong preference for a low-cost and low-input approach to establishing timber trees. Visual observations of farmers' tree establishment practices indicated the existence of gaps in their knowledge of tree growth processes. This investigation illustrates the need to elicit farmers' mental models as a parallel enquiry to extension activities. If agroforestry extension is to be constructivist and participatory, accommodation of farmers' mental models and modification of program goals may be necessary. Relatively little is known about the reasons for farmers' acceptance or rejection of silviculture in Leyte and these results indicate that further research into the way that farmers' mental models filter and guide acceptance of advice may be worthwhile

    An interdisciplinary intervention for older Taiwanese patients after surgery for hip fracture improves health-related quality of life

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    Abstract Background The effects of intervention programs on health-related quality of life (HRQOL) of patients with hip fracture have not been well studied. We hypothesized that older patients with hip fracture who received our interdisciplinary intervention program would have better HRQOL than those who did not. Methods A randomized experimental design was used. Older patients with hip fracture (N = 162), 60 to 98 years old, from a medical center in northern Taiwan were randomly assigned to an experimental (n = 80) or control (n = 82) group. HRQOL was measured by the SF-36 Taiwan version at 1, 3, 6, and 12 months after discharge. Results The experimental group had significantly better overall outcomes in bodily pain (β = 9.38, p = 0.002), vitality (β = 9.40, p < 0.001), mental health (β = 8.16, p = 0.004), physical function (β = 16.01, p < 0.001), and role physical (β = 22.66, p < 0.001) than the control group at any time point during the first year after discharge. Physical-related health outcomes (physical functioning, role physical, and vitality) had larger treatment effects than emotional/mental- and social functioning-related health outcomes. Conclusions This interdisciplinary intervention program may improve health outcomes of elders with hip fracture. Our results may provide a reference for health care providers in countries using similar programs with Chinese/Taiwanese immigrant populations. Trial registration NCT01052636http://deepblue.lib.umich.edu/bitstream/2027.42/78259/1/1471-2474-11-225.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78259/2/1471-2474-11-225.pdfPeer Reviewe

    Threat-sensitive anti-predator defence in precocial wader, the northern lapwing Vanellus vanellus

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    Birds exhibit various forms of anti-predator behaviours to avoid reproductive failure, with mobbing—observation, approach and usually harassment of a predator—being one of the most commonly observed. Here, we investigate patterns of temporal variation in the mobbing response exhibited by a precocial species, the northern lapwing (Vanellus vanellus). We test whether brood age and self-reliance, or the perceived risk posed by various predators, affect mobbing response of lapwings. We quantified aggressive interactions between lapwings and their natural avian predators and used generalized additive models to test how timing and predator species identity are related to the mobbing response of lapwings. Lapwings diversified mobbing response within the breeding season and depending on predator species. Raven Corvus corax, hooded crow Corvus cornix and harriers evoked the strongest response, while common buzzard Buteo buteo, white stork Ciconia ciconia, black-headed gull Chroicocephalus ridibundus and rook Corvus frugilegus were less frequently attacked. Lapwings increased their mobbing response against raven, common buzzard, white stork and rook throughout the breeding season, while defence against hooded crow, harriers and black-headed gull did not exhibit clear temporal patterns. Mobbing behaviour of lapwings apparently constitutes a flexible anti-predator strategy. The anti-predator response depends on predator species, which may suggest that lapwings distinguish between predator types and match mobbing response to the perceived hazard at different stages of the breeding cycle. We conclude that a single species may exhibit various patterns of temporal variation in anti-predator defence, which may correspond with various hypotheses derived from parental investment theory
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