1,249 research outputs found

    Stringent upper limit on the direct 3α decay of the Hoyle state in 12C

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    We investigate an implication of the most recent observation of a second Jπ=2+ state in 12C, which was measured using the 12C(γ,α)8Be(g.s.) reaction. In addition to the dissociation of 12C to an α-particle and 8Be in its ground state, a small fraction of events (2%) were identified as direct decays and decays to excited states in 8Be. This allowed a limit on the direct 3α partial decay width to be determined as Γ3α<32(4) keV. Since this 2+ state is predicted by all theoretical models to be a collective excitation of the Hoyle state, the 3α partial width of the Hoyle state is calculable from the ratio of 3α decay penetrabilities of the Hoyle and 2+ states. This was calculated by using the semiclassical Wenzel-Kramers-Brillouin approach and we deduce a stringent upper limit for the direct decay branching ratio of the Hoyle state of Γ3α Γ <5.7×10−6, over an order of magnitude lower than previously reported. This result places the direct measurement of this rare decay mode beyond current experimental capabilities

    Non-surgical interdisciplinary management for an adult patient with a Class III malocclusion (case report)

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    Non-surgical camouflage orthodontic treatment can be effective for the management of carefully selected patients with mild to moderate Class III malocclusion. This case report demonstrates how a synergistic combination of camouflage orthodontic treatment and appropriate adjunctive restorative procedures provided a pleasing treatment outcome for a patient with a significant skeletal Class III malocclusion and diminutive maxillary lateral incisors

    A snow and glacier hydrological model for large catchments – case study for the Naryn River, central Asia

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    In this paper we implement a degree day snowmelt and glacier melt model in the Dynamic fluxEs and ConnectIvity for Predictions of HydRology (DECIPHeR) model. The purpose is to develop a hydrological model that can be applied to large glaciated and snow-fed catchments yet is computationally efficient enough to include model uncertainty in streamflow predictions. The model is evaluated by simulating monthly discharge at six gauging stations in the Naryn River catchment (57 833 km2) in central Asia over the period 1951 to a variable end date between 1980 and 1995 depending on the availability of discharge observations. The spatial distribution of simulated snow cover is validated against MODIS weekly snow extent for the years 2001–2007. Discharge is calibrated by selecting parameter sets using Latin hypercube sampling and assessing the model performance using six evaluation metrics. The model shows good performance in simulating monthly discharge for the calibration period (NSE is 0.74&lt;NSE&lt;0.87) and validation period (0.7&lt;NSE&lt;0.9), where the range of NSE values represents the 5th–95th percentile prediction limits across the gauging stations. The exception is the Uch-Kurgan station, which exhibits a reduction in model performance during the validation period attributed to commissioning of the Toktogul reservoir in 1975 which impacted the observations. The model reproduces the spatial extent in seasonal snow cover well when evaluated against MODIS snow extent; 86 % of the snow extent is captured (mean 2001–2007) for the median ensemble member of the best 0.5 % calibration simulations. We establish the present-day contributions of glacier melt, snowmelt and rainfall to the total annual runoff and the timing of when these components dominate river flow. The model predicts well the observed increase in discharge during the spring (April–May) associated with the onset of snow melting and peak discharge during the summer (June, July and August) associated with glacier melting. Snow melting is the largest component of the annual runoff (89 %), followed by the rainfall (9 %) and the glacier melt component (2 %), where the values refer to the 50th percentile estimates at the catchment outlet gauging station Uch-Kurgan. In August, glacier melting can contribute up to 66 % of the total runoff at the highly glacierized Naryn headwater sub-catchment. The glaciated area predicted by the best 0.5 % calibration simulations overlaps the Landsat observations for the late 1990s and mid-2000s. Despite good predictions for discharge, the model produces a large range of estimates for the glaciated area (680–1196 km2) (5th–95th percentile limits) at the end of the simulation period. To constrain these estimates further, additional observations such as glacier mass balance, snow depth or snow extent should be used directly to constrain model simulations.</p

    Lung cancer diagnosed following an emergency admission: mixed methods study of the management, outcomes and needs and experiences of patients and carers

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    Background In the UK, although 40% of patients with lung cancer are diagnosed following an emergency admission (EA), data is limited on their needs and experiences as they progress through diagnostic and treatment pathways. Methods Prospective data collection using medical records, questionnaires and in-depth interviews. Multivariate logistic regression explored associations between diagnosis following EA and aspects of interest. Questionnaire responses with 95% confidence intervals were compared with local and national datasets. A grounded theory approach identified patient and carer themes. Results Of 401 patients, 154 (38%) were diagnosed following EA; 37 patients and six carers completed questionnaires and 13 patients and 10 carers were interviewed. Compared to those diagnosed electively, EA patients adjusted results found no difference in treatment recommendation, treatment intent or place of death. Time to diagnosis, review, or treatment was 7–14 days quicker but fewer EA patients had a lung cancer nurse present at diagnosis (37% vs. 62%). Palliative care needs were high (median [IQR] 21 [13–25] distressing or bothersome symptoms/issues) and various information and support needs unmet. Interviews highlighted in particular, perceived delays in obtaining investigations/specialist referral and factors influencing success or failure of the cough campaign. Conclusions Presentation as an EA does not appear to confer any inherent disadvantage regarding progress through lung cancer diagnostic and treatment pathways. However, given the frequent combination of advanced disease, poor performance status and prognosis, together with the high level of need and reported short-fall in care, we suggest that a specialist palliative care assessment is routinely offered

    The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30

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    Tungsten bronze structured materials have attracted attention as possible thermoelectrics because of their complex crystal structure. In this work, a new thermoelectric ceramic with tetragonal tungsten bronze (TB) structure, Ba6Ti2Nb8O30 (BTN) was prepared by the conventional mixed oxide (MO) route with some samples processed by Spark Plasma Sintering (SPS). Additions of MnO enabled fabrication of high density BTN ceramics at the low sintering temperature of 1580 K in air and by SPS. All samples were annealed in a reducing atmosphere after sintering. X-ray diffraction showed that Ba6Ti2Nb8O30 crystallises with tetragonal symmetry (P4bm space group). HAADF-EELS analysis confirmed the proposed crystal structure and provided exact elemental distributions in the lattice, showing higher concentrations of Ti in the 2b lattice sites compared to the 8d lattice sites. XPS showed the presence of two spin-orbit double peaks at 207.7eV in the reduced BTN samples, confirming the presence of Nb4+ ions. By the use of a sintering aid and optimisation of the processing parameters the ceramics achieved a high power factor of 280 μW/m∙K2 at 873 K. The BTN ceramics showed phonon glass type thermal conduction behaviour with low thermal conductivity of 1.7 to 1.65 W/m.K at 300 to 873 K. A thermoelectric figure of merit (ZT) of 0.14 was achieved at 873 K. This ZT value is comparable with results for many TB thermoelectrics. However, BTN has the advantage of much easier processing

    Lung cancer diagnosed following emergency admission: a mixed methods study protocol to improve understanding of patients’ characteristics, needs, experiences and outcomes

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    Background Lung cancer is the leading cause of death from cancer in England. About 40% of patients with lung cancer are diagnosed following an emergency admission (DFEA) to hospital. DFEA is more common in women, and more likely with increasing age and deprivation. Most have advanced disease and survival is poor, but little else is known about this group. The aim of this study is to obtain a detailed understanding of the characteristics, needs, experiences and outcomes of this group. Methods/Design This is a single centre study with quantitative and qualitative work packages (WP). WP1 gathers basic details about all patients diagnosed with lung cancer during a 12 month period, focusing on demographics, diagnostic and treatment pathways and selected outcomes. WP2 obtains information from those patients DFEA or, when unable, their carers, about their holistic needs and experiences, using the Sheffield Profile for Assessment and Referral to Care questionnaire and selected questions from the National Cancer Patient Experience Survey. WP3 uses in-depth qualitative interviews with patients and carers to obtain detailed accounts of their symptoms, help-seeking behaviours prior to admission and subsequent experiences of care. Discussion Relatively little is known about the experiences of lung cancer patients DFEA and this study will provide detailed information about their needs, characteristics, experiences and outcomes. It should identify areas in the diagnostic and treatment pathway where there is scope to improve the care provided to this group of patients and their carers. The findings will also inform the need for further focused research

    Lung cancer diagnosed following an emergency admission: exploring patient and carer perspectives on delay in seeking help

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    Purpose Compared to others, patients diagnosed with lung cancer following an emergency, unplanned admission to hospital (DFEA) have more advanced disease and poorer prognosis. Little is known about DFEA patients’ beliefs about cancer and its symptoms or about their help-seeking behaviours prior to admission. Methods As part of a larger single-centre, prospective mixed-methods study conducted in one University hospital, we undertook qualitative interviews with patients DFEA and their carers to obtain their understanding of symptoms and experiences of trying to access healthcare services before admission to hospital. Interviews were recorded and transcribed. Framework analysis was employed. Results Thirteen patients and 10 carers plus 3 bereaved carers took part in interviews. Three patient/carer dyads were interviewed together. Participants spoke about their symptoms and why they did not seek help sooner. They described complex and nuanced experiences. Some (n = 12) had what they recalled as the wrong symptoms for lung cancer and attributed them either to a pre-existing condition or to ageing. In other cases (n = 9), patients or carers realised with hindsight that their symptoms were signs of lung cancer, but at the time had made other attributions to account for them. In some cases (n = 3), a sudden onset of symptoms was reported. Some GPs (n = 6) were also reported to have made incorrect attributions about cause. Conclusion Late diagnosis meant that patients DFEA needed palliative support sooner after diagnosis than patients not DFEA. Professionals and lay people interpret health and illness experiences differently

    Frequency of health-care utilization by adults who use illicit drugs: a systematic review and meta-analysis.

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    AIMS: To summarize evidence on the frequency and predictors of health-care utilization among people who use illicit drugs. DESIGN: Systematic search of MEDLINE, EMBASE and PsychINFO for observational studies reporting health-care utilization published between 1 January 2000 and 3 December 2018. We conducted narrative synthesis and meta-analysis following a registered protocol (identifier: CRD42017076525). SETTING AND PARTICIPANTS: People who use heroin, powder cocaine, crack cocaine, methamphetamine, amphetamine, ecstasy/3,4-methyl​enedioxy​methamphetamine (MDMA), cannabis, hallucinogens or novel psychoactive substances; have a diagnosis of 'substance use disorder'; or use drug treatment services. MEASUREMENTS: Primary outcomes were the cumulative incidence (risk) and rate of care episodes in three settings: primary care, hospital admissions (in-patient) and emergency department (ED). FINDINGS: Ninety-two studies were included, 84% from North America and Australia. Most studies focused on people using heroin, methamphetamine or crack cocaine, or who had a diagnosis of drug dependence. We were able to conduct a meta-analysis of rates across 25 studies reporting ED episodes and 25 reporting hospital admissions, finding pooled rates of 151 [95% confidence interval (CI) = 114-201] and 41 (95% CI = 30-57) per 100 person-years, respectively; on average 4.8 and 7.1 times more often than the general population. Heterogeneity was very high and was not explained by drugs used, country of study, recruitment setting or demographic characteristics. Predictors of health-care utilization were consistent across studies and included unstable housing, drug injection and mental health problems. Opioid substitution therapy was consistently associated with reduced ED presentation and hospital admission. There was minimal research on health-care utilization by people using ecstasy/MDMA, powder cocaine, hallucinogens or novel psychoactive substances. CONCLUSIONS: People who use illicit drugs are admitted to emergency department or hospital several times more often than the general population

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.
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