3,132 research outputs found

    A microscopic model for Josephson currents

    Full text link
    A microscopic model of a Josephson junction between two superconducting plates is proposed and analysed. For this model, the nonequilibrium steady state of the total system is explicitly constructed and its properties are analysed. In particular, the Josephson current is rigorously computed as a function of the phase difference of the two plates and the typical properties of the Josephson current are recovered

    Correlation Functions in the Two-dimensional Ising Model in a Magnetic Field at T=TcT=T_c

    Get PDF
    The one and two-particle form factors of the energy operator in the two-dimensional Ising model in a magnetic field at T=TcT=T_c are exactly computed within the form factor bootstrap approach. Together with the matrix elements of the magnetisation operator already computed in ref.\,\cite{immf}, they are used to write down the large distance expansion for the correlators of the two relevant fields of the model.Comment: 18 pages, latex, 7 table

    Topological aggregation, the twin paradox and the No Show paradox

    Get PDF
    International audienceConsider the framework of topological aggregation introduced by Chichilnisky (1980). We prove that in this framework the Twin Paradox and the No Show Paradox cannot be avoided. Anonymity and unanimity are not needed to obtain these results

    The Spin-Spin Correlation Function in the Two-Dimensional Ising Model in a Magnetic Field at T=TcT=T_c

    Get PDF
    The form factor bootstrap approach is used to compute the exact contributions in the large distance expansion of the correlation function <σ(x)σ(0)><\sigma(x) \sigma(0)> of the two-dimensional Ising model in a magnetic field at T=TcT=T_c. The matrix elements of the magnetization operator σ(x)\sigma(x) present a rich analytic structure induced by the (multi) scattering processes of the eight massive particles of the model. The spectral representation series has a fast rate of convergence and perfectly agrees with the numerical determination of the correlation function.Comment: 53 pages, latex, 15 figure

    Deep sternal wound infection after open heart surgery: current treatment insights. A retrospective study of 36 cases

    Get PDF
    The aim of this study was to retrospectively evaluate the results of reconstructing infected post-sternotomy wounds, with either sternal plating and/or pectoralis major flap transposition or pedicled omentoplasty after previous vacuum-assisted closure (VAC) therapy. Between January 2005 and December 2010, 36 patients, suffering from deep sternal wound infection (DSWI) after coronary artery bypass grafting procedure, received (plastic) reconstructive surgery. All patients, treated in the Maastricht University Medical Centre (Departments of Plastic Surgery and Cardiothoracic Surgery), were selected for this study. For 22 patients, sternal refixation and reconstruction were obtained by sternal internal plate fixation combined with bilateral pectoralis major advancement flap. In 11 patients, a pedicled omentoplasty was performed, with or without split-skin graft and additional VAC therapy. Three patients only received a pectoralis plasty. We evaluated preoperative characteristics and post-operative course. Twenty-four patients (66.7%) had an uneventful post-operative course. Complications in the other patients included wound dehiscence, herniation of the donor site and infection of sternal plating material. Average sternal wound healing after sternal plating plus pectoralis plasty, pectoralis plasty and omentoplasty respectively accounted 7.7, 8.0 and 11.6 weeks. From our experience, we recommend VAC therapy plus delayed sternal plating and additional bilateral pectoralis major flap advancement as first repair option in case of DSWI. However, individual clinical conditions need to be taken into account when making a decision between the different available reconstructive options. Omentoplasty should be reserved for cases in which the sternum has recurrently fallen open after previous sternal plate refixation, or for cases in which the sternum defect is too extended

    Dietary Vitamin D Intake and Muscle Mass in Older Women. Results from a Cross-Sectional Analysis of the Epidos Study

    Get PDF
    Objectives: Vitamin D intake may prevent physical performance decline through prevention of muscle mass loss. Our objective was to determine whether low dietary intakes were associated with low muscle mass (MM). Design and participants: Cross-sectional analysis of 1989 community-dwelling women (mean age 80.5 +/- 3.8years) from the EPIDemiologie de l\u27OSteoporose (EPIDOS) study were assessed at baseline. Measurements: Low intakes of vitamin D (&lt;70 mu g/week) were estimated from the weekly dietary vitamin D intakes (self-administered food frequency questionnaire). Low MM was defined according to the appendicular skeletal muscle mass index assessed using Dual Energy X-ray Absorptiometry, divided by square height of less than 5.45 kg/m(2). Usual gait speed defined physical performance. Age, sun exposure, co-morbidities, education level, living arrangements, recreational physical activity, dietary protein and calcium intakes, bone mineral density, handgrip strength, and body mass index were considered as potential confounders. Multivariate logistic regression analyses assessed the association between low vitamin D intakes and low MM. Results: Two-hundred and nine (10.5%) women with low MM were compared to 1,780 women with normal MM. In final model, obesity/overweight (Adjusted Odds Ratios, aOR=0.09; 95%CI [0.05-0.17]), malnutrition (aOR=3.90; 95%CI [2.74-5.54]) and low handgrip strength (aOR=2.33; 95%CI [1.44-3.77]; p&lt;0.001) were statistically associated with a low MM status. Conclusion: No association with low MM has been reported regarding low dietary intakes of vitamin D

    Divergent mathematical treatments in utility theory

    Get PDF
    In this paper I study how divergent mathematical treatments affect mathematical modelling, with a special focus on utility theory. In particular I examine recent work on the ranking of information states and the discounting of future utilities, in order to show how, by replacing the standard analytical treatment of the models involved with one based on the framework of Nonstandard Analysis, diametrically opposite results are obtained. In both cases, the choice between the standard and nonstandard treatment amounts to a selection of set-theoretical parameters that cannot be made on purely empirical grounds. The analysis of this phenomenon gives rise to a simple logical account of the relativity of impossibility theorems in economic theory, which concludes the paper

    La Politique Agricole Commune

    Get PDF
    La Politique Agricole Commune (PAC) est l’objet de ce numéro spécial de Regards économiques. Deux articles y sont consacrés. Le premier propose une analyse des effets économiques probables de la réforme récente de la PAC sur l’agriculture belge. Quant au second, il se demande comment rendre la PAC plus juste et plus efficace. La PAC : Une analyse de la réforme récente Les autorités régionales belges doivent se prononcer sur les différentes options de réforme de la PAC proposées par l'accord européen de juin dernier. Cet article examine les effets économiques probables de ces options sur l'agriculture belge à l'aide de deux modèles économiques complémentaires. Ce numéro donne aussi des pistes de réflexion sur quelques questions préoccupantes liées à cet accord et à l'évolution de la PAC. La PAC : Pour la rendre plus juste et plus efficace La PAC est examinée par le biais de trois questions. D’abord, quelles justifications normatives peut-on apporter à un subside de l’activité agricole pour elle même ? Ensuite, qui sont les bénéficiaires ultimes de la PAC dans ses versions passées et présente ? Enfin, peut-on reformuler une PAC dont les effets objectifs répondraient aux critères normatifs énoncés plus haut ?
    corecore