630 research outputs found

    Chiral phase transitions and quantum critical points of the D3/D7(D5) system with mutually perpendicular E and B fields at finite temperature and density

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    We study chiral symmetry restoration with increasing temperature and density in gauge theories subject to mutually perpendicular electric and magnetic fields using holography. We determine the chiral symmetry breaking phase structure of the D3/D7 and D3/D5 systems in the temperature-density-electric field directions. A magnetic field may break the chiral symmetry and an additional electric field induces Ohm and Hall currents as well as restoring the chiral symmetry. At zero temperature the D3/D5 system displays a line of holographic BKT phase transitions in the density-electric field plane, while the D3/D7 system shows a mean-field phase transition. At intermediate temperatures, the transitions in the density-electric field plane are of first order at low density, transforming to second order at critical points as density rises. At high temperature the transition is only ever first order.Comment: 15 pages, 7 figures, v2: Added a referenc

    The effect of high dose antibiotic impregnated cement on rate of surgical site infection after hip hemiarthroplasty for fractured neck of femur : a protocol for a double-blind quasi randomised controlled trial

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    Background: Mortality following hip hemiarthroplasty is in the range of 10-40% in the first year, with much attributed to post-operative complications. One such complication is surgical site infection (SSI), which at the start of this trial affected 4.68% of patients in the UK having this operation. Compared to SSI rates of elective hip surgery, at less than 1%, this figure is elevated. The aim of this quasi randomised controlled trial (RCT) is to determine if high dose antibiotic impregnated cement can reduce the SSI in patients at 12-months after hemiarthroplasty for intracapsular fractured neck of femur. Methods: 848 patients with an intracapsular fractured neck of femur requiring a hip hemiarthroplasty are been recruited into this two-centre double-blind quasi RCT. Participants were recruited before surgery and quasi randomised to standard care or intervention group. Participants, statistician and outcome assessors were blind to treatment allocation throughout the study. The intervention consisted of high dose antibiotic impregnated cement consisting of 1 gram Clindamycin and 1 gram of Gentamicin. The primary outcome is Health Protection Agency (HPA) defined deep surgical site infection at 12 months. Secondary outcomes include HPA defined superficial surgical site infection at 30 days, 30 and 90-day mortality, length of hospital stay, critical care stay, and complications. Discussion: Large randomised controlled trials assessing the effectiveness of a surgical intervention are uncommon, particularly in the speciality of orthopaedics. The results from this trial will inform evidence-based recommendations for antibiotic impregnated cement in the management of patients with a fractured neck of femur undergoing a hip hemiarthroplasty. If high dose antibiotic impregnated cement is found to be an effective intervention, implementation into clinical practice could improve long-term outcomes for patients undergoing hip hemiarthroplasty

    The Baryonic Phase in Holographic Descriptions of the QCD Phase Diagram

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    We study holographic models of the QCD temperature-chemical potential phase diagram based on the D3/D7 system with chiral symmetry breaking. The baryonic phase may be included through linked D5-D7 systems. In a previous analysis of a model with a running gauge coupling a baryonic phase was shown to exist to arbitrarily large chemical potential. Here we explore this phase in a more generic phenomenological setting with a step function dilaton profile. The change in dilaton generates a linear confining qˉq\bar{q}q potential and opposes the screening effect of temperature. We show that the persistence of the baryonic phase depends on the step size and that QCD-like phase diagrams can be described. The baryonic phase's existence is qualitatively linked to the existence of confinement in Wilson loop computations in the background.Comment: 21 pages, 7 figure

    The Coevolution of Virulence: Tolerance in Perspective

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    Coevolutionary interactions, such as those between host and parasite, predator and prey, or plant and pollinator, evolve subject to the genes of both interactors. It is clear, for example, that the evolution of pollination strategies can only be understood with knowledge of both the pollinator and the pollinated. Studies of the evolution of virulence, the reduction in host fitness due to infection, have nonetheless tended to focus on parasite evolution. Host-centric approaches have also been proposed—for example, under the rubric of “tolerance”, the ability of hosts to minimize virulence without necessarily minimizing parasite density. Within the tolerance framework, however, there is room for more comprehensive measures of host fitness traits, and for fuller consideration of the consequences of coevolution. For example, the evolution of tolerance can result in changed selection on parasite populations, which should provoke parasite evolution despite the fact that tolerance is not directly antagonistic to parasite fitness. As a result, consideration of the potential for parasite counter-adaptation to host tolerance—whether evolved or medially manipulated—is essential to the emergence of a cohesive theory of biotic partnerships and robust disease control strategies

    Epidemiological Evidence for Work Load as a Risk Factor for Osteoarthritis of the Hip: A Systematic Review

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    Osteoarthritis of the hip (OA) is a common degenerative disorder of the joint cartilage that presents a major public health problem worldwide. While intrinsic risk factors (e.g, body mass and morphology) have been identified, external risk factors are not well understood. In this systematic review, the evidence for workload as a risk factor for hip OA is summarized and used to derive recommendations for prevention and further research.Epidemiological studies on workload or occupation and osteoarthritis of the hip were identified through database and bibliography searches. Using pre-defined quality criteria, 30 studies were selected for critical evaluation; six of these provided quantitative exposure data.Study results were too heterogeneous to develop pooled risk estimates by specific work activities. The weight of evidence favors a graded association between long-term exposure to heavy lifting and risk of hip OA. Long-term exposure to standing at work might also increase the risk of hip OA.It is not possible to estimate a quantitative dose-response relationship between workload and hip OA using existing data, but there is enough evidence available to identify job-related heavy lifting and standing as hazards, and thus to begin developing recommendations for preventing hip OA by limiting the amount and duration of these activities. Future research to identify specific risk factors for work-related hip OA should focus on implementing rigorous study methods with quantitative exposure measures and objective diagnostic criteria

    Quality of dietary fat and genetic risk of type 2 diabetes: individual participant data meta-analysis.

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    OBJECTIVE: To investigate whether the genetic burden of type 2 diabetes modifies the association between the quality of dietary fat and the incidence of type 2 diabetes. DESIGN: Individual participant data meta-analysis. DATA SOURCES: Eligible prospective cohort studies were systematically sourced from studies published between January 1970 and February 2017 through electronic searches in major medical databases (Medline, Embase, and Scopus) and discussion with investigators. REVIEW METHODS: Data from cohort studies or multicohort consortia with available genome-wide genetic data and information about the quality of dietary fat and the incidence of type 2 diabetes in participants of European descent was sought. Prospective cohorts that had accrued five or more years of follow-up were included. The type 2 diabetes genetic risk profile was characterized by a 68-variant polygenic risk score weighted by published effect sizes. Diet was recorded by using validated cohort-specific dietary assessment tools. Outcome measures were summary adjusted hazard ratios of incident type 2 diabetes for polygenic risk score, isocaloric replacement of carbohydrate (refined starch and sugars) with types of fat, and the interaction of types of fat with polygenic risk score. RESULTS: Of 102 305 participants from 15 prospective cohort studies, 20 015 type 2 diabetes cases were documented after a median follow-up of 12 years (interquartile range 9.4-14.2). The hazard ratio of type 2 diabetes per increment of 10 risk alleles in the polygenic risk score was 1.64 (95% confidence interval 1.54 to 1.75, I2=7.1%, τ2=0.003). The increase of polyunsaturated fat and total omega 6 polyunsaturated fat intake in place of carbohydrate was associated with a lower risk of type 2 diabetes, with hazard ratios of 0.90 (0.82 to 0.98, I2=18.0%, τ2=0.006; per 5% of energy) and 0.99 (0.97 to 1.00, I2=58.8%, τ2=0.001; per increment of 1 g/d), respectively. Increasing monounsaturated fat in place of carbohydrate was associated with a higher risk of type 2 diabetes (hazard ratio 1.10, 95% confidence interval 1.01 to 1.19, I2=25.9%, τ2=0.006; per 5% of energy). Evidence of small study effects was detected for the overall association of polyunsaturated fat with the risk of type 2 diabetes, but not for the omega 6 polyunsaturated fat and monounsaturated fat associations. Significant interactions between dietary fat and polygenic risk score on the risk of type 2 diabetes (P>0.05 for interaction) were not observed. CONCLUSIONS: These data indicate that genetic burden and the quality of dietary fat are each associated with the incidence of type 2 diabetes. The findings do not support tailoring recommendations on the quality of dietary fat to individual type 2 diabetes genetic risk profiles for the primary prevention of type 2 diabetes, and suggest that dietary fat is associated with the risk of type 2 diabetes across the spectrum of type 2 diabetes genetic risk.The EPIC-InterAct study received funding from the European Union (Integrated Project LSHM-CT-2006-037197 in the Framework Programme 6 of the European Community). We thank all EPIC participants and staff for their contribution to the study. We thank Nicola Kerrison (MRC Epidemiology Unit, University of Cambridge, Cambridge, UK) for managing the data for the InterAct Project. In addition, InterAct investigators acknowledge funding from the following agencies: MT: Health Research Fund (FIS) of the Spanish Ministry of Health; the CIBER en Epidemiología y Salud Pública (CIBERESP), Spain; Murcia Regional Government (N° 6236); JS: JS was supported by a Heisenberg-Professorship (SP716/2-1), a Clinical Research Group (KFO218/1) and a research group (Molecular Nutrition to JS) of the Bundesministerium für Bildung und Forschung (BMBF); YTvdS, JWJB, PHP, IS: Verification of diabetes cases was additionally funded by NL Agency grant IGE05012 and an Incentive Grant from the Board of the UMC Utrecht; HBBdM: Dutch Ministry of Public Health, Welfare and Sports (VWS), Netherlands Cancer Registry (NKR), LK Research Funds, Dutch Prevention Funds, Dutch ZON (Zorg Onderzoek Nederland), World Cancer Research Fund (WCRF), Statistics Netherlands (The Netherlands); MDCL: Health Research Fund (FIS) of the Spanish Ministry of Health; Murcia Regional Government (N° 6236); FLC: Cancer Research UK; PD: Wellcome Trust; LG: Swedish Research Council; GH: The county of Västerbotten; RK: Deutsche Krebshilfe; TJK: Cancer Research UK; KK: Medical Research Council UK, Cancer Research UK; AK: Medical Research Council (Cambridge Lipidomics Biomarker Research Initiative); CN: Health Research Fund (FIS) of the Spanish Ministry of Health; Murcia Regional Government (N° 6236); KO: Danish Cancer Society; OP: Faculty of Health Science, 47 University of Aarhus, Denmark; JRQ: Asturias Regional Government; LRS: Asturias Regional Government; AT: Danish Cancer Society; RT: AIRE-ONLUS Ragusa, AVIS-Ragusa, Sicilian Regional Government; DLvdA, WMMV: Dutch Ministry of Public Health, Welfare and Sports (VWS), Netherlands Cancer Registry (NKR), LK Research Funds, Dutch Prevention Funds, Dutch ZON (Zorg Onderzoek Nederland), World Cancer Research Fund (WCRF), Statistics Netherlands (The Netherlands); MMC: Wellcome Trust (083270/Z/07/Z), MRC (G0601261)
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