63,405 research outputs found
Chaos suppression in the large size limit for long-range systems
No full textWe consider the class of long-range Hamiltonian systems first introduced by Anteneodo and Tsallis and called the alpha -XY model. This involves N classical rotators on a d-dimensional periodic lattice interacting all to all with an attractive coupling whose strength decays as r(-alpha), r being the distance between sites. Using a recent geometrical approach, we estimate for any d-dimensional lattice the scaling of the largest Lyapunov exponent (LLE) with N, as a function of a in the large energy regime where rotators behave almost freely. We find that the LLE vanishes as N-kappa, with kappa = 1/3 for 0 less than or equal to alpha /d less than or equal to 1/2 and kappa = 2/3(1 - alpha /d) for 1/2 less than or equal to alpha /d < 1. These analytical results present a nice agreement with numerical results obtained by Campa et al, including deviations at small N
The limestone industry of the paleolithic site of Isernia La Pineta (Molise, Italy): an interpretative model of the behavioral strategies
No full textInhomogeneous quasi-stationary states in a mean-field model with repulsive cosine interactions
No full textThe system of N particles moving on a circle and interacting via a global repulsive cosine interaction is well known to display spatially inhomogeneous structures of extraordinary stability starting from certain low-energy initial conditions. The aim of this paper is to show in a detailed manner how these structures arise and to explain their stability. By a convenient canonical transformation we rewrite the Hamiltonian in such a way that fast and slow variables are singled out and the canonical coordinates of a collective mode are naturally introduced. If, initially, enough energy is put in this mode, its decay can be extremely slow. However, both analytical arguments and numerical simulations suggest that these structures eventually decay to the spatially uniform equilibrium state, although this can happen on impressively long time scales. Finally, we heuristically introduce a one-particle time-dependent Hamiltonian that well reproduces most of the observed phenomenology
On the properties of the Lambda value at risk: robustness, elicitability and consistency
No full textRecently, the financial industry and regulators have enhanced the debate on the good properties of a risk measure. A fundamental issue is the evaluation of the quality of a risk estimation. On the one hand, a backtesting procedure is desirable for assessing the accuracy of such an estimation and this can be naturally achieved by elicitable risk measures. For the same objective, an alternative approach has been introduced by Davis [Stat. Risk Model. Appl. Finance Insurance, 2016, 33, 67–93] through the so-called consistency property. On the other hand, a risk estimation should be less sensitive with respect to small changes in the available data-set and exhibit qualitative robustness. A new risk measure, the Lambda value at risk (), has been recently proposed by Frittelli et al. [Math. Finance, 2014, 24, 442–463], as a generalization of VaR with the ability to discriminate the risk among P&L distributions with different tail behaviour. In this article, we show that also satisfies the properties of robustness, elicitability and consistency under some conditions
Optimizing operating conditions and electrochemical characterization of glucose-gluconate alkaline fuel cells
No full textThe direct oxidation of glucose to produce electrical energy has been widely investigated because of renewability, abundance, high energy density and easy handling of the carbohydrate. Most of the previous studies have been conducted in extreme conditions in order to achieve complete glucose oxidation to CO2, neglecting the carbohydrate chemical instability that generally leads to useless by-products mixtures. The partial oxidation to gluconate, originally studied for implantable fuel cells, has the advantage of generating a commercially valuable chemical. In the present paper we optimized fuel composition and operating conditions in order to selectively oxidize glucose to gluconate, maximizing the power density output of a standard commercial platinum based anode material. A deep electrochemical characterization concerning reversible potential, cyclic voltammetry and overpotential measurements have been carried out at 25 °C in the d-(+)-glucose concentration range 1.0 × 10-2 to 1.0 M. NMR and EIS investigation clarify the role of the buffer in enhancing the electrochemical performance
Electrophilic attack of [I(py)2]+(NO3-) to three-coordinate Pt(0) precursors: synthesis and in vitro antitumor activity of water soluble Pt(II) five-coordinate complexes
No full textUlteriore coautore: VITO A
The identification and registration of bovine as the sistem of traceability in European Food Law
No full textProfili sanzionatori in materia di “anagrafe canina, tutela degli animali d’affezione e prevenzione del randagismo”
No full textLa responsabilità del medico veterinario conseguente al rifiuto o al ritardo di soccorso urgente
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