1,685 research outputs found

    Potential evapotranspiration-related uncertainty in climate change impacts on river flow: An assessment for the Mekong River basin

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    SummarySix MIKE SHE models of the Mekong are developed, each employing potential evapotranspiration (PET) derived using alternative methods: Blaney–Criddle (BC), Hamon (HM), Hargreaves–Samani (HS), Linacre (LN), Penman (PN) and Priestley–Taylor (PT). Baseline (1961–1990) PET varies, with PT followed by HS providing the lowest totals, LN and BC the highest. The largest mean annual PET is over 1.5times the smallest. Independent calibration of each model results in different optimised parameter sets that mitigate differences in baseline PET. Performance of each model is “excellent” (monthly NSE>0.85) or “very good” (NSE: 0.65–0.85). Scenarios based on seven GCMs for a 2°C increase in global mean temperature are investigated. Inter-GCM variation in precipitation change is much larger (in percentage terms by 2.5–10times) than inter-GCM differences in PET change. Precipitation changes include catchment-wide increases or decreases as well as spatially variable directions of change, whereas PET increases for all scenarios. BC and HS produce the smallest changes, LN and HM the largest. PET method does impact scenario discharges. However, GCM-related uncertainty for change in mean discharge is on average 3.5times greater than PET method-related uncertainty. Scenarios with catchment-wide precipitation increases (decreases) induce increases (decreases) in mean discharge irrespective of PET method. Magnitude of change in discharge is conditioned by PET method; larger increases or smaller declines in discharge result from methods producing the smallest PET increases. Uncertainty in the direction of change in mean discharge due to PET method occurs for scenarios with spatially variable precipitation change, although this is limited to few gauging stations and differences are relatively small. For all scenarios, PET method-related uncertainty in direction of change in high and low flows occurs, but seasonal distribution of discharge is largely unaffected. As such, whilst PET method does influence projections of discharge, variation in the precipitation climate change signal between GCMs is a much larger source of uncertainty

    Spin-3/2 Nucleon and Delta Baryons in Lattice QCD

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    We present first results for masses of spin-3/2 N and Delta baryons in lattice QCD using Fat-Link Irrelevant Clover (FLIC) fermions. Spin-3/2 interpolating fields providing overlap with both spin-3/2 and spin-1/2 states are considered. In the isospin-1/2 sector, we observe, after appropriate spin and parity projection, a strong signal for the J^P=3/2^- state together with a weak but discernible signal for the 3/2^+ state with a mass splitting near that observed experimentally. We also find good agreement between the 1/2^+/- masses and earlier nucleon mass simulations with the standard spin-1/2 interpolating field. For the isospin-3/2 Delta states, clear mass splittings are observed between the various 1/2^+/- and 3/2^+/- channels, with the calculated level orderings in good agreement with those observed empirically.Comment: 17 pages, 8 figures, 2 table

    Elastic scattering and breakup of 17^F at 10 MeV/nucleon

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    Angular distributions of fluorine and oxygen produced from 170 MeV 17^F incident on 208^Pb were measured. The elastic scattering data are in good agreement with optical model calculations using a double-folding potential and parameters similar to those obtained from 16^O+208^Pb. A large yield of oxygen was observed near \theta_lab=36 deg. It is reproduced fairly well by a calculation of the (17^F,16^O) breakup, which is dominated by one-proton stripping reactions. The discrepancy between our previous coincidence measurement and theoretical predictions was resolved by including core absorption in the present calculation.Comment: 9 pages, 5 figure

    Excited Baryons in Lattice QCD

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    We present first results for the masses of positive and negative parity excited baryons calculated in lattice QCD using an O(a^2)-improved gluon action and a fat-link irrelevant clover (FLIC) fermion action in which only the irrelevant operators are constructed with APE-smeared links. The results are in agreement with earlier calculations of N^* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner. An correlation matrix analysis reveals two low-lying J^P=(1/2)^- states with a small mass splitting. The study of different Lambda interpolating fields suggests a similar splitting between the lowest two Lambda1/2^- octet states. However, the empirical mass suppression of the Lambda^*(1405) is not evident in these quenched QCD simulations, suggesting a potentially important role for the meson cloud of the Lambda^*(1405) and/or a need for more exotic interpolating fields.Comment: Correlation matrix analysis performed. Increased to 400 configurations. 22 pages, 13 figures, 15 table

    The Upper Limit of Magnetic Field Strength in Dense Stellar Hadronic Matter

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    It is shown that in strongly magnetized neutron stars, there exist upper limits of magnetic field strength, beyond which the self energies for both neutron and proton components of neutron star matter become complex in nature. As a consequence they decay within the strong interaction time scale. However, in the ultra-strong magnetic field case, when the zeroth Landau level is only occupied by protons, the system again becomes stable against strong decay.Comment: 6 pages Revtex, 2 .eps figures, fig.(1) is not include

    Mild parenchymal lung disease and/or low diffusion capacity impacts survival and treatment response in patients diagnosed with idiopathic pulmonary arterial hypertension

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    There are limited published data defining survival and treatment response in patients with mild lung disease and/or reduced gas transfer who fulfil diagnostic criteria for idiopathic pulmonary arterial hypertension (IPAH). Patients diagnosed with IPAH between 2001–19 were identified in the ASPIRE registry. Using pre-specified criteria based on CT imaging and spirometry, patients with a diagnosis of IPAH and no lung disease were termed IPAHno-LD (n=303), and those with minor-mild emphysema or fibrosis were described as IPAHmild-LD (n=190). Survival was significantly better in IPAHno-LD than in IPAHmild-LD (1 and 5-year survival 95% and 70% versus 78% and 22% respectively, p<0.0001). In the combined group of IPAHno-LD and IPAHmild-LD, independent predictors of higher mortality were increasing age, lower DLCO, lower exercise capacity and a diagnosis of IPAHmild-LD (p all <0.05). Exercise capacity and quality of life improved (p both <0.0001) following treatment in patients with IPAHno-LD but not IPAHmild-LD. A proportion of patients with IPAHno-LD had a DLCO <45%; these patients had poorer survival than patients with DLCO ≥45% although demonstrated improved exercise capacity following treatment. The presence of even mild parenchymal lung disease in patients who would be classified as IPAH according to current recommendations has a significant adverse effect on outcomes. This phenotype can be identified using lung function testing and clinical CT reports. Patients with IPAH, no lung disease and severely reduced DLCO may represent a further distinct phenotype. These data suggest that RCTs of targeted therapies in patients with these phenotypes are required

    Shape Matching and Object Recognition

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    We approach recognition in the framework of deformable shape matching, relying on a new algorithm for finding correspondences between feature points. This algorithm sets up correspondence as an integer quadratic programming problem, where the cost function has terms based on similarity of corresponding geometric blur point descriptors as well as the geometric distortion between pairs of corresponding feature points. The algorithm handles outliers, and thus enables matching of exemplars to query images in the presence of occlusion and clutter. Given the correspondences, we estimate an aligning transform, typically a regularized thin plate spline, resulting in a dense correspondence between the two shapes. Object recognition is handled in a nearest neighbor framework where the distance between exemplar and query is the matching cost between corresponding points. We show results on two datasets. One is the Caltech 101 dataset (Li, Fergus and Perona), a challenging dataset with large intraclass variation. Our approach yields a 45 % correct classification rate in addition to localization. We also show results for localizing frontal and profile faces that are comparable to special purpose approaches tuned to faces

    Adults’ experiences of living with pulmonary hypertension: a thematic synthesis of qualitative studies

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    Objectives Pulmonary hypertension is a life-shortening disease that has a considerable impact on quality of life. Improving our understanding of how individuals are affected and cope with the disease will help to improve services and outcomes. This review synthesises the published qualitative research that has listened to adults discuss their experiences of living with the disease. Design A comprehensive systematic search of four databases was conducted in May 2020: Web of Science, PubMed, PsycINFO and Cochrane Library. Suitable studies were evaluated using the Critical Appraisal Skills programme. Findings from the studies were extracted and subjected to a thematic synthesis. Results Nineteen articles were identified reflecting the experiences of over 1900 individuals impacted by pulmonary hypertension from Europe, North and South America and Asia. Ten studies did not report participant’s WHO functional class of pulmonary hypertension, which resulted in comparing experiences between different severity difficult. All studies met the majority of the quality assessment items. Six descriptive themes emerged discussing participant’s experiences of diagnosis, treatment, prognosis, healthcare professionals, impact and coping with pulmonary hypertension. Four higher order analytical themes were developed from the descriptive themes, reflecting: (i) uncertainties and anxiety that participants encountered related to pulmonary hypertension; (ii) lack of recognition of the impact of the condition; (iii) frustration at the paucity of awareness of pulmonary hypertension in society and healthcare settings and (iv) participant’s accounts of transitioning through different stages of living with the disease. Conclusions These findings form the first synthesis of experiences of life in individuals impacted by pulmonary hypertension and illustrate the multifaceted impact of the condition. The voices of numerous groups are missing from the literature highlighting the need for additional research. The results have implications for clinical practice emphasising the role of educational and psychological therapies to support those with the disease

    Milagrito: a TeV air-shower array

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    Milagrito, a large, covered water-Cherenkov detector, was the world's first air-shower-particle detector sensitive to cosmic gamma rays below 1 TeV. It served as a prototype for the Milagro detector and operated from February 1997 to May 1998. This paper gives a description of Milagrito, a summary of the operating experience, and early results that demonstrate the capabilities of this technique.Comment: 38 pages including 24 figure
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