758 research outputs found

    Phase diagram of vortex matter in layered superconductors with random point pinning

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    We study the phase diagram of the superconducting vortex system in layered high-temperature superconductors in the presence of a magnetic field perpendicular to the layers and of random atomic scale point pinning centers. We consider the highly anisotropic limit where the pancake vortices on different layer are coupled only by their electromagnetic interaction. The free energy of the vortex system is then represented as a Ramakrishnan-Yussouff free energy functional of the time averaged vortex density. We numerically minimize this functional and examine the properties of the resulting phases. We find that, in the temperature (TT) -- pinning strength (ss) plane at constant magnetic induction, the equilibrium phase at low TT and ss is a Bragg glass. As one increases ss or TT a first order phase transition occurs to another phase that we characterize as a pinned vortex liquid. The weakly pinned vortex liquid obtained for high TT and small ss smoothly crosses over to the strongly pinned vortex liquid as TT is decreased or ss increased -- we do not find evidence for the existence, in thermodynamic equilibrium, of a distinct vortex glass phase in the range of pinning parameters considered here. %cdr We present results for the density correlation functions, the density and defect distributions, and the local field distribution accessible via μ\muSR experiments. These results are compared with those of existing theoretical, numerical and experimental studies.Comment: 15 pages, including figures. Higher resolution files for Figs 3a and 11 available from author

    Enhancement of Writeback Caching by changes in flush and its parameters

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    Achievement of high performance in computing or accessing of data is the aim of any system. Reduction of access time to a particular data which is present in the device is very important for the enhancement in the performance. Caching is implemented to do the same. The group of cache device and the virtual device is made as a cache group to enhance the performance of the system. The system may not be on the same condition different instances of time. There will always be a variation in io rates of the application, which is not utilized for the full extent. These differences in the io rates can be utilized effectively for the enhancement of the performance of the system. When the system is idle of with less io then the system will force the flush so that the inconsistency of data is reduced. When the system is being bombarded with io then less threads are given for the flush io. These variations in the threads assigned for the implementation of flush io will enhance the overall performance of the system

    Melting and structure of the vortex solid in strongly anisotropic layered superconductors with random columnar pins

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    We study the melting transition of the low-temperature vortex solid in strongly anisotropic layered superconductors with a concentration of random columnar pinning centers small enough so that the areal density of the pins is much less than that of the vortex lines. Both the external magnetic field and the columnar pins are assumed to be oriented perpendicular to the layers Our method, involving numerical minimization of a model free energy functional, yields not only the free energy values at the local minima of the functional but also the detailed density distribution of the system at each minimum: this allows us to study in detail the structure of the different phases. We find that at these pin concentrations and low temperatures, the thermodynamically stable state is a topologically ordered Bragg glass. This nearly crystalline state melts into an interstitial liquid (a liquid in which a small fraction of vortex lines remain localized at the pinning centers) in two steps, so that the Bragg glass and the liquid are separated by a narrow phase that we identify from analysis of its density structure as a polycrystalline Bose glass. Both the Bragg glass to Bose glass and the Bose glass to interstitial liquid transitions are first-order. We also find that a local melting temperature defined using a criterion based on the degree of localization of the vortex lines exhibits spatial variations similar to those observed in recent experiments.Comment: 17 page

    Hydrodynamics of superfluids confined in blocked rings and wedges

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    Motivated by many recent experimental studies of non-classical rotational inertia (NCRI) in superfluid and supersolid samples, we present a study of the hydrodynamics of a superfluid confined in the two-dimensional region (equivalent to a long cylinder) between two concentric arcs of radii bb and aa (b<ab<a) subtending an angle β\beta, with 0β2π0 \le \beta \le 2\pi. The case β=2π\beta= 2 \pi corresponds to a blocked ring. We discuss the methodology to compute the NCRI effects, and calculate these effects both for small angular velocities, when no vortices are present, and in the presence of a vortex. We find that, for a blocked ring, the NCRI effect is small, and that therefore there will be a large discontinuity in the moment of inertia associated with blocking or unblocking circular paths. For blocked wedges (b=0b=0) with β>π\beta > \pi, we find an unexpected divergence of the velocity at the origin, which implies the presence of either a region of normal fluid or a vortex for {\it any} nonzero value of the angular velocity. Implications of our results for experiments on "supersolid" behavior in solid 4He^4{\rm He} are discussed. A number of mathematical issues are pointed out and resolved.Comment: 15 pages, including figures. To appear in Phys. Rev.

    Validity and interpretation of spirometric recordings to diagnose COPD in UK primary care.

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    BACKGROUND: The diagnosis of COPD is dependent upon clinical judgment and confirmation of the presence of airflow obstruction using spirometry. Spirometry is now routinely available; however, spirometry incorrectly performed or interpreted can lead to misdiagnosis. We aimed to determine whether spirometry undertaken in primary care for patients suspected to have COPD was of sufficient quality and whether their spirometry was correctly interpreted. METHODS: Two chest physicians re-read all spirometric readings for both quality of the procedure and interpretation, received as a part of COPD validation studies using data from the Clinical Practice Research Datalink (CPRD). We then used logistic regression to investigate predictors of correct interpretation. RESULTS: Spirometry traces were obtained for 306 patients, of which 221 (72.2%) were conducted in primary care. Of those conducted in primary care, 98.6% (n=218) of spirometry traces were of adequate quality. Of those traces that were of adequate quality and conducted in primary care, and in whom a general practitioner (GP) diagnosis of COPD had been made, 72.5% (n=218) were consistent with obstruction. Historical records for asthma diagnosis significantly decreased odds of correct interpretation. CONCLUSION: The quality of the spirometry procedure undertaken in primary care is high. However, this was not reflected in the quality of interpretation, suggesting an unmet training in primary care. The quality of the spirometry procedure as demonstrated by spirometric tracings provides a re-assurance for the use of spirometric values available in the electronic health care record databases for research purposes

    Novel Bacterial Diversity and Fragmented eDNA Identified in Hyperbiofilm-Forming Pseudomonas aeruginosa Rugose Small Colony Variant

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    Pseudomonas aeruginosa biofilms represent a major threat to health care. Rugose small colony variants (RSCV) of P. aeruginosa, isolated from chronic infections, display hyperbiofilm phenotype. RSCV biofilms are highly resistant to antibiotics and host defenses. This work shows that RSCV biofilm aggregates consist of two distinct bacterial subpopulations that are uniquely organized displaying contrasting physiological characteristics. Compared with that of PAO1, the extracellular polymeric substance of RSCV PAO1ΔwspF biofilms presented unique ultrastructural characteristics. Unlike PAO1, PAO1ΔwspF released fragmented extracellular DNA (eDNA) from live cells. Fragmented eDNA, thus released, was responsible for resistance of PAO1ΔwspF biofilm to disruption by DNaseI. When added to PAO1, such fragmented eDNA enhanced biofilm formation. Disruption of PAO1ΔwspF biofilm was achieved by aurine tricarboxylic acid, an inhibitor of DNA-protein interaction. This work provides critical novel insights into the contrasting structural and functional characteristics of a hyperbiofilm-forming clinical bacterial variant relative to its own wild-type strain

    Extended Self-similarity in Kinetic Surface Roughening

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    We show from numerical simulations that a limited mobility solid-on-solid model of kinetically rough surface growth exhibits extended self-similarity analogous to that found in fluid turbulence. The range over which scale-independent power-law behavior is observed is significantly enhanced if two correlation functions of different order, such as those representing two different moments of the difference in height between two points, are plotted against each other. This behavior, found in both one and two dimensions, suggests that the `relative' exponents may be more fundamental than the `absolute' ones.Comment: 4 pages, 4 postscript figures included (some changes made according to referees' comments. accepted for publication in PRE Rapid Communication

    Comparison of functional outcomes and complications of conservative management verses surgical fixation with a locking compression plate in the treatment of displaced middle third clavicular fracture

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    Background: About 3 to 5 percent of all fractures are clavicle fractures, which account for 45 percent of fractures at the shoulder. While fractures of the lateral and medial thirds of the clavicle account for 15% and 5% of all clavicle fractures, respectively, middle third fractures account for 80% of all clavicle fractures.Methods: patients were divided into two groups at random. Patients selected for conservative treatment with figure of eight Clavicle Brace and arm sling/pouch were treated with the brace immediately and for surgical intervention with locking plating. Constant and Murley's scoring system was used to check for signs of healing and functional improvementResults: The 40 patients in the current study include 20 with a new fracture of the mid-third clavicle who underwent surgical treatment with clavicular locking compression plate and screws and 20 who underwent conservative treatment with a figure-eight clavicle brace and arm pouch/sling. There was a statistically significant difference in the Constant and Murley score between the surgical group and the conservative group.Conclusions: According to the present study, patients with a displaced mid-third clavicle fracture may benefit more from surgery than from conservative treatment.

    Effectiveness of Computer Automation for the Diagnosis and Management of Childhood Type 2 Diabetes A Randomized Clinical Trial

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    Importance Type 2 diabetes (T2D) is increasingly common in young individuals. Primary prevention and screening among children and adolescents who are at substantial risk for T2D are recommended, but implementation of T2D screening practices in the pediatric primary care setting is uncommon. Objective To determine the feasibility and effectiveness of a computerized clinical decision support system to identify pediatric patients at high risk for T2D and to coordinate screening for and diagnosis of prediabetes and T2D. Design, Setting, and Participants This cluster-randomized clinical trial included patients from 4 primary care pediatric clinics. Two clinics were randomized to the computerized clinical decision support intervention, aimed at physicians, and 2 were randomized to the control condition. Patients of interest included children, adolescents, and young adults 10 years or older. Data were collected from January 1, 2013, through December 1, 2016. Interventions Comparison of physician screening and follow-up practices after adding a T2D module to an existing computer decision support system. Main Outcomes and Measures Electronic medical record (EMR) data from patients 10 years or older were reviewed to determine the rates at which pediatric patients were identified as having a body mass index (BMI) at or above the 85th percentile and 2 or more risk factors for T2D and underwent screening for T2D. Results Medical records were reviewed for 1369 eligible children (712 boys [52.0%] and 657 girls [48.0%]; median [interquartile range] age, 12.9 [11.2-15.3]), of whom 684 were randomized to the control group and 685 to the intervention group. Of these, 663 (48.4%) had a BMI at or above the 85th percentile. Five hundred sixty-five patients (41.3%) met T2D screening criteria, with no difference between control and intervention sites. The T2D module led to a significant increase in the percentage of patients undergoing screening for T2D (89 of 283 [31.4%] vs 26 of 282 [9.2%]; adjusted odds ratio, 4.6; 95% CI, 1.5-14.7) and a greater proportion attending a scheduled follow-up appointment (45 of 153 [29.4%] vs 38 of 201 [18.9%]; adjusted odds ratio, 1.8; 95% CI, 1.5-2.2). Conclusions and Relevance Use of a computerized clinical decision support system to automate the identification and screening of pediatric patients at high risk for T2D can help overcome barriers to the screening process. The support system significantly increased screening among patients who met the American Diabetes Association criteria and adherence to follow-up appointments with primary care clinicians

    Free Energy Landscape Of Simple Liquids Near The Glass Transition

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    Properties of the free energy landscape in phase space of a dense hard sphere system characterized by a discretized free energy functional of the Ramakrishnan-Yussouff form are investigated numerically. A considerable number of glassy local minima of the free energy are located and the distribution of an appropriately defined ``overlap'' between minima is calculated. The process of transition from the basin of attraction of a minimum to that of another one is studied using a new ``microcanonical'' Monte Carlo procedure, leading to a determination of the effective height of free energy barriers that separate different glassy minima. The general appearance of the free energy landscape resembles that of a putting green: deep minima separated by a fairly flat structure. The growth of the effective free-energy barriers with increasing density is consistent with the Vogel-Fulcher law, and this growth is primarily driven by an entropic mechanism.Comment: 10 pages, 6 postscript figures, uses iopart.cls and iopart10.clo (included). Invited talk at the ICTP Trieste Conference on "Unifying Concepts in Glass Physics", September 1999. To be published in J. Phys. Cond. Ma
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