3,358 research outputs found

    Holographic Superconductors from Einstein-Maxwell-Dilaton Gravity

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    We construct holographic superconductors from Einstein-Maxwell-dilaton gravity in 3+1 dimensions with two adjustable couplings α\alpha and the charge qq carried by the scalar field. For the values of α\alpha and qq we consider, there is always a critical temperature at which a second order phase transition occurs between a hairy black hole and the AdS RN black hole in the canonical ensemble, which can be identified with the superconducting phase transition of the dual field theory. We calculate the electric conductivity of the dual superconductor and find that for the values of α\alpha and qq where α/q\alpha/q is small the dual superconductor has similar properties to the minimal model, while for the values of α\alpha and qq where α/q\alpha/q is large enough, the electric conductivity of the dual superconductor exhibits novel properties at low frequencies where it shows a "Drude Peak" in the real part of the conductivity.Comment: 25 pages, 13 figures; v2, typos corrected; v3, refs added, to appear in JHE

    Modelling the viral dynamics of the SARS-CoV-2 Delta and Omicron variants in different cell types.

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    We use viral kinetic models fitted to viral load data from in vitro studies to explain why the SARS-CoV-2 Omicron variant replicates faster than the Delta variant in nasal cells, but slower than Delta in lung cells, which could explain Omicron's higher transmission potential and lower severity. We find that in both nasal and lung cells, viral infectivity is higher for Omicron but the virus production rate is higher for Delta, with an estimated approximately 200-fold increase in infectivity and 100-fold decrease in virus production when comparing Omicron with Delta in nasal cells. However, the differences are unequal between cell types, and ultimately lead to the basic reproduction number and growth rate being higher for Omicron in nasal cells, and higher for Delta in lung cells. In nasal cells, Omicron alone can enter via a TMPRSS2-independent pathway, but it is primarily increased efficiency of TMPRSS2-dependent entry which accounts for Omicron's increased activity. This work paves the way for using within-host mathematical models to understand the transmission potential and severity of future variants

    Safety management of waterway congestions under dynamic risk conditions—A case study of the Yangtze River

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    With the continuous increase of traffic volume in recent years, inland waterway transportation suffers more and more from congestion problems, which form a major impediment to its development. Thus, it is of great significance for the stakeholders and decision makers to address these congestion issues properly. Fuzzy Techniques for Order Preference by Similarity to an Ideal Solution (TOPSIS) is widely used for solving Multiple Criteria Decision Making (MCDM) problems with ambiguity. When taking into account fuzzy TOPSIS, decisions are made in a static scenario with fixed weights assigned to the criteria. However, risk conditions usually vary in real-life cases, which will inevitably affect the preference ranking of the alternatives. To make flexible decisions according to the dynamics of congestion risks and to achieve a rational risk analysis for prioritising congestion risk control options (RCOs), the cost-benefit ratio (CBR) is used in this paper to reflect the change of risk conditions. The hybrid of CBR and fuzzy TOPSIS is illustrated by investigating the congestion risks of the Yangtze River. The ranking of RCOs varies depending on the scenarios with different congestion risk conditions. The research findings indicate that some RCOs (e.g. “Channel dredging and maintenance”, and “Prohibition of navigation”) are more cost effective in the situation of a high level of congestion risk, while the other RCOs (e.g. “Loading restriction”, and “Crew management and training”) are more beneficial in a relatively low congestion risk condition. The proposed methods and the evaluation results provide useful insights for effective safety management of the inland waterway congestions under dynamic risk conditions. © 2017 Elsevier B.V

    Geographic variation in the treatment of non-ST-segment myocardial infarction in the English National Health Service: a cohort study

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    Objectives: To investigate geographic variation in guideline-indicated treatments for NSTEMI in the English National Health Service (NHS). Design: Cohort study using registry data from the Myocardial Ischaemia National Audit Project. Setting: All Clinical Commissioning Groups (CCGs) (n=211) in the English NHS. Participants: 357,228 patients with NSTEMI between 1st January, 2003 and 30th June, 2013. Main outcome measure: Proportion of eligible NSTEMI who received all eligible guideline-indicated treatments (optimal care) according to the date of guideline publication. Results: The proportion of NSTEMI who received optimal care was low (48,257/357,228; 13.5%) and varied between CCGs (median 12.8%, interquartile range 0.7 to 18.1%). The greatest geographic variation was for aldosterone antagonists (16.7%, 0.0 to 40.0%) and least for use of an electrocardiogram (96.7%, 92.5 to 98.7%). The highest rates of care were for acute aspirin (median 92.8%, interquartile range 88.6 to 97.1%), and aspirin (90.1%, 85.1 to 93.3%) and statins (86.4%, 82.3 to 91.2%) at hospital discharge. The lowest rates were for smoking cessation advice (median 11.6%, interquartile range 8.7 to 16.6%), dietary advice (32.4%, 23.9 to 41.7%) and the prescription of P2Y12 inhibitors (39.7%, 32.4 to 46.9%). After adjustment for case mix, nearly all (99.6%) of the variation was due to between hospitals differences (median 64.7%, interquartile range 57.4% to 70.0%; between hospital variance: 1.92, 95% confidence interval 1.51 to 2.44; interclass correlation 0.996, 0.976 to 0.999). Conclusions: Across the English NHS, the optimal use of guideline-indicated treatments for NSTEMI was low. Variation in the use of specific treatments for NSTEMI was mostly explained by between-hospital differences in care. Performance-based commissioning may increase the use of NSTEMI treatments and, therefore, reduce premature cardiovascular deaths

    Association of Clinical Factors and Therapeutic Strategies With Improvements in Survival Following Non-ST-Elevation Myocardial Infarction, 2003-2013.

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    Importance: International studies report a decline in mortality following non–ST-elevation myocardial infarction (NSTEMI). Whether this is due to lower baseline risk or increased utilization of guideline-indicated treatments is unknown. Objective: To determine whether changes in characteristics of patients with NSTEMI are associated with improvements in outcomes. Design, Setting, and Participants: Data on patients with NSTEMI in 247 hospitals in England and Wales were obtained from the Myocardial Ischaemia National Audit Project between January 1, 2003, and June 30, 2013 (final follow-up, December 31, 2013). Exposures: Baseline demographics, clinical risk (GRACE risk score), and pharmacological and invasive coronary treatments. Main Outcomes and Measures: Adjusted all-cause 180-day postdischarge mortality time trends estimated using flexible parametric survival modeling. Results: Among 389 057 patients with NSTEMI (median age, 72.7 years [IQR, 61.7-81.2 years]; 63.1% men), there were 113 586 deaths (29.2%). From 2003-2004 to 2012-2013, proportions with intermediate to high GRACE risk decreased (87.2% vs 82.0%); proportions with lowest risk increased (4.2% vs 7.6%; P= .01 for trend). The prevalence of diabetes, hypertension, cerebrovascular disease, chronic obstructive pulmonary disease, chronic renal failure, previous invasive coronary strategy, and current or ex-smoking status increased (all P < .001). Unadjusted all-cause mortality rates at 180 days decreased from 10.8% to 7.6% (unadjusted hazard ratio [HR], 0.968 [95% CI, 0.966-0.971]; difference in absolute mortality rate per 100 patients [AMR/100], −1.81 [95% CI, −1.95 to −1.67]). These findings were not substantially changed when adjusted additively by baseline GRACE risk score (HR, 0.975 [95% CI, 0.972-0.977]; AMR/100, −0.18 [95% CI, −0.21 to −0.16]), sex and socioeconomic status (HR, 0.975 [95% CI, 0.973-0.978]; difference in AMR/100, −0.24 [95% CI, −0.27 to −0.21]), comorbidities (HR, 0.973 [95% CI, 0.970-0.976]; difference in AMR/100, −0.44 [95% CI, −0.49 to −0.39]), and pharmacological therapies (HR, 0.972 [95% CI, 0.964-0.980]; difference in AMR/100, −0.53 [95% CI, −0.70 to −0.36]). However, the direction of association was reversed after further adjustment for use of an invasive coronary strategy (HR, 1.02 [95% CI, 1.01-1.03]; difference in AMR/100, 0.59 [95% CI, 0.33-0.86]), which was associated with a relative decrease in mortality of 46.1% (95% CI, 38.9%-52.0%). Conclusions and Relevance: Among patients hospitalized with NSTEMI in England and Wales, improvements in all-cause mortality were observed between 2003 and 2013. This was significantly associated with use of an invasive coronary strategy and not entirely related to a decline in baseline clinical risk or increased use of pharmacological therapies

    Evaluation of the impact of the GRACE risk score on the management and outcome of patients hospitalised with non-ST elevation acute coronary syndrome in the UK: protocol of the UKGRIS cluster-randomised registry-based trial

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    Introduction For non-ST-segment elevation acute coronary syndrome (NSTEACS) there is a gap between the use of class 1 guideline recommended therapies and clinical practice. The GRACE risk score is recommended in international guidelines for the risk stratification of NSTEACS, but its impact on adherence to guideline-indicated treatments and reducing adverse clinical outcomes is unknown. The objective of the UKGRIS trial is to assess the effectiveness of the GRACE risk score tool and associated treatment recommendations on the use of guideline-indicated care and clinical outcomes. Methods and Analysis The UK GRACE Risk Score Intervention Study (UKGRIS), a parallel-group cluster randomised registry-based controlled trial, will allocate hospitals in a 1:1 ratio to manage NSTEACS by standard care or according to the GRACE risk score and associated international guidelines. UKGRIS will recruit a minimum of 3000 patients from at least 30 English National Health Service hospitals and collect healthcare data from national electronic health records. The co-primary endpoints are the use of guideline-indicated therapies, and the composite of cardiovascular death, non-fatal myocardial infarction, new onset heart failure hospitalisation or cardiovascular readmission at 12 months. Secondary endpoints include duration of inpatient hospital stay over 12 months, EQ-5D-5L responses and utilities, unscheduled revascularisation and the components of the composite endpoint over 12 months follow-up. Ethics and Dissemination The study has ethical approval (North East - Tyne & Wear South Research Ethics Committee ref: 4/NE/1180). Findings will be announced at relevant conferences and published in peer-reviewed journals in line with the funder’s open access policy. Registration ISRCTN29731761, registered 12th January 2017

    Social interactions through the eyes of macaques and humans

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    Group-living primates frequently interact with each other to maintain social bonds as well as to compete for valuable resources. Observing such social interactions between group members provides individuals with essential information (e.g. on the fighting ability or altruistic attitude of group companions) to guide their social tactics and choice of social partners. This process requires individuals to selectively attend to the most informative content within a social scene. It is unclear how non-human primates allocate attention to social interactions in different contexts, and whether they share similar patterns of social attention to humans. Here we compared the gaze behaviour of rhesus macaques and humans when free-viewing the same set of naturalistic images. The images contained positive or negative social interactions between two conspecifics of different phylogenetic distance from the observer; i.e. affiliation or aggression exchanged by two humans, rhesus macaques, Barbary macaques, baboons or lions. Monkeys directed a variable amount of gaze at the two conspecific individuals in the images according to their roles in the interaction (i.e. giver or receiver of affiliation/aggression). Their gaze distribution to non-conspecific individuals was systematically varied according to the viewed species and the nature of interactions, suggesting a contribution of both prior experience and innate bias in guiding social attention. Furthermore, the monkeys’ gaze behavior was qualitatively similar to that of humans, especially when viewing negative interactions. Detailed analysis revealed that both species directed more gaze at the face than the body region when inspecting individuals, and attended more to the body region in negative than in positive social interactions. Our study suggests that monkeys and humans share a similar pattern of role-sensitive, species- and context-dependent social attention, implying a homologous cognitive mechanism of social attention between rhesus macaques and humans
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