599 research outputs found

    Radio observations of the planetary nebula around the OH/IR Star OH354.88-0.54 (V1018 Sco)

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    We present radio observations of the unique, recently formed, planetary nebula (PN) associated with a very long-period OH/IR variable star V1018 Sco that is unequivocally still in its asymptoticgiant branch phase. Two regions within the optical nebula are clearly detected in nonthermal radio continuum emission, with radio spectral indices comparable to those seen in colliding-wind Wolf-Rayet binaries. We suggest that these represent shocked interactions between the hot, fast stellar wind and the cold nebular shell that represents the PN's slow wind moving away from the central star. This same interface produces both synchrotron radio continuum and the optical PN emission. The fast wind is neither spherical in geometry nor aligned withany obvious optical or radio axis. We also report the detection of transient H2O maser emission in this nebula.Comment: 11 pages, LaTeX (mn2e.cls), incl. 9 PostScript (ps or eps) figures and 2 tables. Accepted by MNRA

    Moving forward in circles: challenges and opportunities in modelling population cycles

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    Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research

    Fluorescent biomarkers demonstrate prospects for spreadable vaccines to control disease transmission in wild bats

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    Vaccines that autonomously transfer among individuals have been proposed as a strategy to control infectious diseases within inaccessible wildlife populations. However, rates of vaccine spread and epidemiological efficacy in real-world systems remain elusive. Here, we investigate whether topical vaccines that transfer among individuals through social contacts can control vampire bat rabies—a medically and economically important zoonosis in Latin America. Field experiments in three Peruvian bat colonies, which used fluorescent biomarkers as a proxy for the bat-to-bat transfer and ingestion of an oral vaccine, revealed that vaccine transfer would increase population-level immunity up to 2.6 times beyond the same effort using conventional, non-spreadable vaccines. Mathematical models showed that observed levels of vaccine transfer would reduce the probability, size and duration of rabies outbreaks, even at low but realistically achievable levels of vaccine application. Models further predicted that existing vaccines provide substantial advantages over culling bats—the policy currently implemented in North, Central and South America. Linking field studies with biomarkers to mathematical models can inform how spreadable vaccines may combat pathogens of health and conservation concern before costly investments in vaccine design and testing

    Mapping the disease-specific LupusQoL to the SF-6D

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    Purpose To derive a mapping algorithm to predict SF-6D utility scores from the non-preference-based LupusQoL and test the performance of the developed algorithm on a separate independent validation data set. Method LupusQoL and SF-6D data were collected from 320 patients with systemic lupus erythematosus (SLE) attending routine rheumatology outpatient appointments at seven centres in the UK. Ordinary least squares (OLS) regression was used to estimate models of increasing complexity in order to predict individuals’ SF-6D utility scores from their responses to the LupusQoL questionnaire. Model performance was judged on predictive ability through the size and pattern of prediction errors generated. The performance of the selected model was externally validated on an independent data set containing 113 female SLE patients who had again completed both the LupusQoL and SF-36 questionnaires. Results Four of the eight LupusQoL domains (physical health, pain, emotional health, and fatigue) were selected as dependent variables in the final model. Overall model fit was good, with R2 0.7219, MAE 0.0557, and RMSE 0.0706 when applied to the estimation data set, and R2 0.7431, MAE 0.0528, and RMSE 0.0663 when applied to the validation sample. Conclusion This study provides a method by which health state utility values can be estimated from patient responses to the non-preference-based LupusQoL, generalisable beyond the data set upon which it was estimated. Despite concerns over the use of OLS to develop mapping algorithms, we find this method to be suitable in this case due to the normality of the SF-6D data

    Incarceration history and risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis

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    Background People who inject drugs (PWID) experience a high prevalence of incarceration and might be at high risk of HIV and hepatitis C virus (HCV) infection during or after incarceration. We aimed to assess whether incarceration history elevates HIV or HCV acquisition risk among PWID. Methods In this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO databases for studies in any language published from Jan 1, 2000 until June 13, 2017 assessing HIV or HCV incidence among PWID. We included studies that measured HIV or HCV incidence among community-recruited PWID. We included only studies reporting original results and excluded studies that evaluated incident infections by self-report. We contacted authors of cohort studies that met the inclusion or exclusion criteria, but that did not report on the outcomes of interest, to request data. We extracted and pooled data from the included studies using random-effects meta-analyses to quantify the associations between recent (past 3, 6, or 12 months or since last follow-up) or past incarceration and HIV or HCV acquisition (primary infection or reinfection) risk among PWID. We assessed the risk of bias of included studies using the Newcastle-Ottawa Scale. Between-study heterogeneity was evaluated using the I2 statistic and the P-value for heterogeneity. Findings We included published results from 20 studies and unpublished results from 21 studies. These studies originated from Australasia, western and eastern Europe, North and Latin America, and east and southeast Asia. Recent incarceration was associated with an 81% (relative risk [RR] 1·81, 95% CI 1·40–2·34) increase in HIV acquisition risk, with moderate heterogeneity between studies (I2=63·5%; p=0·001), and a 62% (RR 1·62, 95% CI 1·28–2·05) increase in HCV acquisition risk, also with moderate heterogeneity between studies (I2=57·3%; p=0·002). Past incarceration was associated with a 25% increase in HIV (RR 1·25, 95% CI 0·94–1·65) and a 21% increase in HCV (1·21, 1·02–1·43) acquisition risk. Interpretation Incarceration is associated with substantial short-term increases in HIV and HCV acquisition risk among PWID and could be a significant driver of HCV and HIV transmission among PWID. These findings support the need for developing novel interventions to minimise the risk of HCV and HIV acquisition, including addressing structural risks associated with drug laws and excessive incarceration of PWID

    Society for Endocrinology (SfE) guidelines for the diagnosis and management of post bariatric hypoglycaemia

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    Post-bariatric hypoglycaemia (PBH) is typically a post-prandial hypoglycaemia occurring about 2–4 h after eating in individuals who have undergone bariatric surgery. PBH develops relatively late after surgery and often after discharge from post-surgical follow-up by bariatric teams, leading to variability in diagnosis and management in non-specialist centres.AimThe overall aim was to improve and standardise clinical practice in the diagnosis and management of PBH. The objectives were: (1) to undertake an up-to-date review of the current literature; (2) to formulate practical and evidence-based guidance regarding the diagnosis and treatment of PBH; (3) to recommend future avenues for research in this condition.MethodA scoping review was undertaken after an extensive literature search. A consensus on the guidance and confidence in the recommendations was reached by the steering group authors prior to review by key stakeholders.OutcomeWe make pragmatic recommendations for the practical diagnosis and management of PBH, including criteria for diagnosis and recognition, as well as recommendations for research areas that should be explored.Plain English summaryPost-bariatric hypoglycaemia (PBH) is a condition that commonly affects people who have undergone weight loss surgery. In this condition, people develop low blood sugar occurring about 2–4 h after meals, leading to debilitating symptoms such as hunger, sweating, anxiety, palpitations and even blackouts and fainting. PBH is becoming more common as weight loss surgery is being taken up by more people to help with their weight and to help with diabetes. The condition often develops after the patient has been discharged from follow-up after their surgery, which can lead to inconsistent diagnosis and treatment in non-specialist healthcare centres. The lack of clear information and evidence in the existing scientific literature further contributes to the variation in care. To address this problem, the Society for Endocrinology has created new guidelines to help healthcare professionals accurately diagnose and manage this condition. The guidelines were developed with input from dietitians, surgeons and doctors specialising in weight loss, and hormone specialists

    “We Don’t Get Into All That”: an analysis of how teachers uphold heteronormative sex and relationship education

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    Legislation that applies to UK SRE currently advocates inclusive provision. Given the nonstatutory status of SRE, however, it is unclear how teachers incorporate sexual inclusivity, especially as research has shown that teachers’ discursive practices can promote a heteronormative SRE climate (Renn, 2010). Using a discursive psychological approach to analyze interview data, this study examined how teachers account for their provision as inclusive. It was revealed that even when promoting their inclusivity, teachers’ SRE provision upholds heteronormativity. In doing this, they positioned LGB and same-sex practices outside of the classroom, potentially leaving these young people without a sufficient sex education
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