205 research outputs found

    Critical Behavior of the Supersolid transition in Bose-Hubbard Models

    Full text link
    We study the phase transitions of interacting bosons at zero temperature between superfluid (SF) and supersolid (SS) states. The latter are characterized by simultaneous off-diagonal long-range order and broken translational symmetry. The critical phenomena is described by a long-wavelength effective action, derived on symmetry grounds and verified by explicit calculation. We consider two types of supersolid ordering: checkerboard (X) and collinear (C), which are the simplest cases arising in two dimensions on a square lattice. We find that the SF--CSS transition is in the three-dimensional XY universality class. The SF--XSS transition exhibits non-trivial new critical behavior, and appears, within a d=3ϵd=3-\epsilon expansion to be driven generically first order by fluctuations. However, within a one--loop calculation directly in d=2d=2 a strong coupling fixed point with striking ``non-Bose liquid'' behavior is found. At special isolated multi-critical points of particle-hole symmetry, the system falls into the 3d Ising universality class.Comment: RevTeX, 24 pages, 16 figures. Also available at http://www.cip.physik.tu-muenchen.de/tumphy/d/T34/Mitarbeiter/frey.htm

    The Grounds and Extent of Legal Responsibility

    Get PDF
    To question that is the title of this symposium, What Do Compensatory Damages Compensate?, requires consideration of the basic grounds and purposes of legal responsibility. The question is usefully brought into sharper focus by the specific questions and puzzles posed to the contributors to stimulate thought and discussion

    New-Sum: A Novel Online ABFT Scheme for General Iterative Methods

    Get PDF
    Emerging high-performance computing platforms, with large component counts and lower power margins, are anticipated to be more susceptible to soft errors in both logic circuits and memory subsystems. We present an online algorithm-based fault tolerance (ABFT) approach to efficiently detect and recover soft errors for general iterative methods. We design a novel checksum-based encoding scheme for matrix-vector multiplication that is resilient to both arithmetic and memory errors. Our design decouples the checksum updating process from the actual computation, and allows adaptive checksum overhead control. Building on this new encoding mechanism, we propose two online ABFT designs that can effectively recover from errors when combined with a checkpoint/rollback scheme. These designs are capable of addressing scenarios under different error rates. Our ABFT approaches apply to a wide range of iterative solvers that primarily rely on matrix-vector multiplication and vector linear operations. We evaluate our designs through comprehensive analytical and empirical analysis. Experimental evaluation on the Stampede supercomputer demonstrates the low performance overheads incurred by our two ABFT schemes for preconditioned CG (0:4% and 2:2%) and preconditioned BiCGSTAB (1:0% and 4:0%) for the largest SPD matrix from UFL Sparse Matrix Collection. The evaluation also demonstrates the exibility and effectiveness of our proposed designs for detecting and recovering various types of soft errors in general iterative methods

    The study demands and resources scale:psychometric properties, longitudinal invariance, and criterion validity

    Get PDF
    The Study Demands and Resources Scale (SDRS) has shown promise as a valid and reliable measure for measuring students’ specific study demands and -resources. However, there is no evidence as to its psychometric properties outside of the original context in which it was developed. This study aimed to assess the psychometric properties of the SDRS in a cross-national student population through examining its longitudinal factorial validity, internal consistency, and temporal invariance as well as criterion validity through its association with study engagement and task performance over time. Results showed that a Bifactor Exploratory Structural Equation Model (ESEM) with one general factor (overall study characteristics) and five specific factors (workload, growth opportunities, lecturer support, peer support, information availability) fitted the data, showed strong measurement invariance over time, and was reliable at different time points. The study further established criterion validity for the overall study characteristics factor through its concurrent and predictive associations with study engagement and task performance. However, the specific factors’ concurrent and predictive capacity could only partially be established when controlling for the general study characteristics factor. These findings suggest that study characteristics should be measured as a dynamic interaction between study demands and resources, rather than a hierarchical model.</p

    Left Ventricular Global Longitudinal Strain in Patients with Moderate Aortic Stenosis

    Get PDF
    BackgroundModerate aortic stenosis (AS) is associated with an increased risk for adverse events. Although reduced left ventricular (LV) global longitudinal strain (GLS) is associated with worse outcomes in patients with severe AS, its prognostic value in patients with moderate AS is unknown. The aim of this study was to investigate the prognostic implications of LV GLS in patients with moderate AS.MethodsLV GLS was evaluated using speckle-tracking echocardiography in patients with moderate AS (aortic valve area 1.0-1.5 cm2) and reported as absolute (i.e., positive) values. Patients were divided into three groups: LV ejection fraction (LVEF) ResultsA total of 760 patients (mean age, 71 ± 12 years; 61% men) were analyzed. During a median follow-up period of 50 months (interquartile range, 26-94 months), 257 patients (34%) died. Patients with LVEF P P = .592). LV GLS discriminated higher risk patients even among those with LVEF ≥ 60% (P P P P ConclusionsIn patients with moderate AS, reduced LV GLS is associated with an increased risk for all-cause mortality, even if LVEF is still preserved.</p

    Genotyping of clinical isolates of Aspergillus flavus and its relationship with environmental isolates center

    Get PDF
    Antecedentes: Durante un período de 4 meses, y mientras se llevaba a cabo un muestreo ambiental de aire, se diagnosticaron 2 casos de aspergilosis por Aspergillus flavus en un centro oncohematológico de Buenos Aires, Argentina. Objetivos: Conocer la variabilidad y la relación genética entre los aislamientos clínicos y los ambientales obtenidos en el centro oncohematológico. Métodos: Se utilizaron 2 técnicas de genotipificación con diferente poder discriminatorio (RAPD y AFLP). Una matriz de similitud genética fue calculada usando el método de Jaccard y fue la base para la cons- trucción de un dendrograma por el método de UPGMA. Se estimó el nivel de variabilidad genética por medio del porcentaje de loci polimórficos, número de alelos efectivos y heterocigosidad esperada, y el índice de asociación (I A ) . Resultados: El dendrograma mostró que los aislamientos de A. flavus recuperados de los pacientes no se relacionaron genéticamente con los del ambiente nosocomial. Los valores más altos de diversidad gené- tica correspondieron a los aislamientos ambientales. El I A estimado para todos los aislamientos sugiere eventos de recombinación. Conclusiones: Los pacientes 1 y 2 no fueron infectados con los aislamientos obtenidos del ambiente hospitalario. Los aislamientos clínicos y ambientales de A. flavus mostraron alta variabilidad genética entre ellos

    Role of computed tomography imaging for transcatheter valvular repair/insertion

    Get PDF
    During the last decade, the development of transcatheter based therapies has provided feasible therapeutic options for patients with symptomatic severe valvular heart disease who are deemed inoperable. The promising results of many nonrandomized series and recent landmark trials have increased the number of percutaneous transcatheter valve procedures in high operative risk patients. Pre-procedural imaging of the anatomy of the aortic or mitral valve and their spatial relationships is crucial to select the most appropriate device or prosthesis and to plan the percutaneous procedure. Multidetector row computed tomography provides 3-dimensional volumetric data sets allowing unlimited plane reconstructions and plays an important role in pre-procedural screening and procedural planning. This review will describe the evolving role of multidetector row computed tomography in patient selection and strategy planning of transcatheter aortic and mitral valve procedures

    Sex-Related Differences in Medically Treated Moderate Aortic Stenosis

    Get PDF
    BackgroundRecent data showed poor long-term survival in patients with moderate AS. Although sex differences in left ventricular (LV) remodeling and outcome are well described in severe AS, it has not been evaluated in moderate AS.MethodsIn this retrospective, multicenter study, patients with a first diagnosis of moderate AS diagnosed between 2001 and 2019 were identified. Clinical and echocardiographic parameters were recorded at baseline and compared between men and women. Patients were followed up for the primary endpoint of all-cause mortality with censoring at the time of aortic valve replacement.ResultsA total of 1895 patients with moderate AS (age 73 ± 10 years, 52% male) were included. Women showed more concentric hypertrophy and had more pronounced LV diastolic dysfunction than men. During a median follow-up of 34 (13-60) months, 682 (36%) deaths occurred. Men showed significantly higher mortality rates at 3- and 5-year follow-up (30% and 48%, respectively) than women (26% and 39%, respectively) (p = 0.011). On multivariable analysis, male sex remained independently associated with mortality (hazard ratio 1.209; 95% CI: 1.024-1.428; p = 0.025). LV remodeling (according to LV mass index) was associated with worse outcomes (hazard ratio 1.003; CI: 1.001-1.005; p = 0.006), but no association was observed between the interaction of LV mass index and sex with outcomes.ConclusionsLV remodeling patterns are different between men and women having moderate AS. Male sex is associated with worse outcomes in patients with medically treated moderate AS. Further studies investigating the management of moderate AS in a sex-specific manner are needed.</p

    Amygdala 14-3-3ζ as a Novel Modulator of Escalating Alcohol Intake in Mice

    Get PDF
    Alcoholism is a devastating brain disorder that affects millions of people worldwide. The development of alcoholism is caused by alcohol-induced maladaptive changes in neural circuits involved in emotions, motivation, and decision-making. Because of its involvement in these processes, the amygdala is thought to be a key neural structure involved in alcohol addiction. However, the molecular mechanisms that govern the development of alcoholism are incompletely understood. We have previously shown that in a limited access choice paradigm, C57BL/6J mice progressively escalate their alcohol intake and display important behavioral characteristic of alcohol addiction, in that they become insensitive to quinine-induced adulteration of alcohol. This study used the limited access choice paradigm to study gene expression changes in the amygdala during the escalation to high alcohol consumption in C57BL/6J mice. Microarray analysis revealed that changes in gene expression occurred predominantly after one week, i.e. during the initial escalation of alcohol intake. One gene that stood out from our analysis was the adapter protein 14-3-3ζ, which was up-regulated during the transition from low to high alcohol intake. Independent qPCR analysis confirmed the up-regulation of amygdala 14-3-3ζ during the escalation of alcohol intake. Subsequently, we found that local knockdown of 14-3-3ζ in the amygdala, using RNA interference, dramatically augmented alcohol intake. In addition, knockdown of amygdala 14-3-3ζ promoted the development of inflexible alcohol drinking, as apparent from insensitivity to quinine adulteration of alcohol. This study identifies amygdala 14-3-3ζ as a novel key modulator that is engaged during escalation of alcohol use
    corecore