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