892 research outputs found

    Ricci Flow from the Renormalization of Nonlinear Sigma Models in the Framework of Euclidean Algebraic Quantum Field Theory

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    The perturbative approach to nonlinear Sigma models and the associated renormalization group flow are discussed within the framework of Euclidean algebraic quantum field theory and of the principle of general local covariance. In particular we show in an Euclidean setting how to define Wick ordered powers of the underlying quantum fields and we classify the freedom in such procedure by extending to this setting a recent construction of Khavkine, Melati and Moretti for vector valued free fields. As a by-product of such classification, we prove that, at first order in perturbation theory, the renormalization group flow of the nonlinear Sigma model is the Ricci flow.Comment: 24 page

    GPGPU for track finding in High Energy Physics

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    The LHC experiments are designed to detect large amount of physics events produced with a very high rate. Considering the future upgrades, the data acquisition rate will become even higher and new computing paradigms must be adopted for fast data-processing: General Purpose Graphics Processing Units (GPGPU) is a novel approach based on massive parallel computing. The intense computation power provided by Graphics Processing Units (GPU) is expected to reduce the computation time and to speed-up the low-latency applications used for fast decision taking. In particular, this approach could be hence used for high-level triggering in very complex environments, like the typical inner tracking systems of the multi-purpose experiments at LHC, where a large number of charged particle tracks will be produced with the luminosity upgrade. In this article we discuss a track pattern recognition algorithm based on the Hough Transform, where a parallel approach is expected to reduce dramatically the execution time.Comment: 6 pages, 4 figures, proceedings prepared for GPU-HEP 2014 conference, submitted to DESY-PROC-201

    Solving non-monotone equilibrium problems via a DIRECT-type approach

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    A global optimization approach for solving non-monotone equilibrium problems (EPs) is proposed. The class of (regularized) gap functions is used to reformulate any EP as a constrained global optimization program and some bounds on the Lipschitz constant of such functions are provided. The proposed global optimization approach is a combination of an improved version of the \texttt{DIRECT} algorithm, which exploits local bounds of the Lipschitz constant of the objective function, with local minimizations. Unlike most existing solution methods for EPs, no monotonicity-type condition is assumed in this paper. Preliminary numerical results on several classes of EPs show the effectiveness of the approach.Comment: Technical Report of Department of Computer Science, University of Pisa, Ital

    ASSESSING SPREADABILITY OF WARM SEASON SPECIES USED FOR TURFGRASS ON THREE TYPES OF SUBSTRATE IN THE MEDITERRANEAN ENVIRONMENT

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    The aim of the study was to examine the performance of turfgrass warm season species, including 6 varieties of Cynodon dactylon in comparison with Zoysia japonica and Paspalum vaginatum in three substrates with different soil textures (sandy loam, sandy clay loam, clay), to find the one or the ones that adapt best in the Mediterranean environment. The results showed the best perfomances in sandy loam substrate and for C.dactylon cv. Transcontinental, Capriola and La Paloma. Z. japonica, Zenith, had lower values

    Heart transplantation without informed consent: discussion of a case

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    OBJECTIVE: To discuss informed consent to heart transplantation in the case of an intensive care unit (ICU) patient: relatives' informed consent was refused by the patient himself whose cognitive ability appeared to be reasonable for the purpose. SETTING: ICU of a university teaching hospital. PATIENT: A 62-year-old man who underwent myocardial revascularization had in the immediate post-operative hemodynamic instability, continuous serious arrhythmias, ventilatory support, fentanyl infusion. Heart transplantation could be the only chance for his survival. INVENTION: Heart transplantation. RESULTS: Despite patient's refusal, we decided to hold the relative's consent as valid, and transplantation was accordingly performed, to the subsequent satisfaction of the patient. CONCLUSIONS: Our decision was based on two beliefs: (1) the severity of the patient's clinical condition may have impaired his cognitive abilities; (2) the very same conditions may mask impairment and certainly make reliable assessment of cognition and judgment impossible. This being so, the preservation of life assumes priority
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