5,397 research outputs found

    Tomographic approach to the violation of Bell's inequalities for quantum states of two qutrits

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    The tomographic method is employed to investigate the presence of quantum correlations in two classes of parameter-dependent states of two qutrits. The violation of some Bell's inequalities in a wide domain of the parameter space is shown. A comparison between the tomographic approach and a recent method elaborated by Wu, Poulsen and Molmer shows the better adequacy of the former method with respect to the latter one.Comment: 9 pages, 4 figure

    Ionization signals from electrons and alpha-particles in mixtures of liquid Argon and Nitrogen - perspectives on protons for Gamma Resonant Nuclear Absorption applications

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    In this paper we report on a detailed study of ionization signals produced by Compton electrons and alpha-particles in a Time Projection Chamber (TPC) flled with different mixtures of liquid Argon and Nitrogen. The measurements were carried out with Nitrogen concentrations up to 15% and a drift electric feld in the range 0-50 kV/cm. A prediction for proton ionization signals is made by means of interpolation. This study has been conducted in view of the possible use of liquid Ar-N2 TPCs for the detection of gamma-rays in the resonant band of the Nitrogen absorption spectrum, a promising technology for security and medical applications

    30 kV coaxial vacuum-tight feedthrough for operation at cryogenic temperatures

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    In this paper we describe the technology of building a vacuum-tight high voltage feedthrough which is able to operate at voltages up to 30 kV. The feedthrough has a coaxial structure with a grounded sheath which makes it capable to lead high voltage potentials into cryogenic liquids, without risk of surface discharges in the gas phase above the liquid level. The feedthrough is designed to be used in ionization detectors, based on liquefied noble gases, such as Argon or Xenon

    The visual binary AG Tri in β\beta Pictoris Association: can a debris disc cause very different rotation periods of its components?

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    We measure the photometric rotation periods of the components of multiple systems in young stellar associations to investigate the causes of the observed rotation period dispersion. We present the case of the wide binary AG Tri in the 23-Myr young beta Pictoris Association consisting of K4 + M1 dwarfs. Our multi-band, multi-season photometric monitoring allowed us to measure the rotation periods of both components P_A = 12.4d and P_B = 4.66d, to detect a prominent magnetic activity in the photosphere, likely responsible for the measured radial velocity variations, and for the first time, a flare event on the M1 component AG Tri B. We investigate either the possibility that the faster rotating component may have suffered an enhanced primordial disc dispersal, starting its PMS spin-up earlier than the slower rotating component, or the possibility that the formation of a debris disc may have prevented AG Tri A from gaining part of the angular momentum from the accreting disc.Comment: 28 pages, 7 figures, accepted for publication in Astrophysics and Space Science 2015, (ASTR-D-15-00445R2

    Polyelectrolyte Multilayering on a Charged Planar Surface

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    The adsorption of highly \textit{oppositely} charged flexible polyelectrolytes (PEs) on a charged planar substrate is investigated by means of Monte Carlo (MC) simulations. We study in detail the equilibrium structure of the first few PE layers. The influence of the chain length and of a (extra) non-electrostatic short range attraction between the polycations and the negatively charged substrate is considered. We show that the stability as well as the microstructure of the PE layers are especially sensitive to the strength of this latter interaction. Qualitative agreement is reached with some recent experiments.Comment: 28 pages; 11 (main) Figs - Revtex4 - Higher resolution Figs can be obtained upon request. To appear in Macromolecule

    Biometry traits and geometric morphometrics in sea bass (Dicentrarchus labrax) from different farming systems

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    The effect of the farming system on biometry traits and dressing out yield were inves- tigated in market-size European sea bass (Dicentrarchus labrax) cultured extensively or intensively in sea cages or land-based basins. Fish external appearences and shapes were studies with geometric morphometrics in order to assess the potential of combined methodologies in the assessment of finfish quality. Both standard biometry and geometric morphometrics were able to discriminate between sea bass farmed extensively from those cultured under intensive conditions. Geometric morphometrics has been shown to be a valuable tool for describing changes in shape features and could result a useful technique to be associated to biometry traits in the context of fish quality assessment

    Rilievi e indagini diagnostiche non distruttive per l’individuazione delle cripte - La Cattedrale di Ragusa

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    I diversi operatori, che si occupano di Beni Storici e Culturali, si avvalgono sempre più spesso delle soluzioni tecnologiche avanzate offerte dalla moderna Geomatica, facendo ricorso ad integrazioni delle sue discipline, per meglio studiare, indagare e monitorare un bene di interesse storico. Oggi si tentano nuove integrazioni con altre discipline che, tradizionalmente, non riguardano il campo del rilievo propriamente detto. Questo è, ad esempio, il caso dello studio condotto sulla Cattedrale di San Giovanni a Ragusa, nel quale si è partiti dal rilievo laser scanning di una porzione della chiesa e del suo pregiatissimo pavimento, sotto il quale secondo uno schizzo dei primi anni del XIX secolo (Fig. 1) dovrebbero trovarsi delle sepolture, per poi proseguire lo studio con l’ausilio del Georadar, strumento utilizzato tradizionalmente da geofisici e geologi per indagare il terreno. Ciò è stato fatto al fine di verificare l’effettiva presenza di strutture ipogee senza però agire con indagini invasive. Il risultato dell’elaborazione dei dati georadar, trasformato in una ricostruzione tridimensionale del sottopavimento, è stato affiancato alla ricostruzione tridimensionale della chiesa, realizzata dall’elaborazione dei dati del rilievo laser scanning. Tale integrazione ha permesso di confermare la presenza di strutture ipogee e di capire in che relazione sono queste ultime con gli avvallamenti presenti nel pavimento della chiesa. Del modello tridimensionale completo si è, infine, realizzata una versione navigabile (VRML), capace di offrire una visualizzazione e un’interazione anche ad utenti privi di conoscenze informatiche approfondite

    Nonlinear heat transport in superlattices with mobile defects

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    We consider heat conduction in a superlattice with mobile defects, which reduce the thermal conductivity of the material. If the defects may be dragged by the heat flux, and if they are stopped at the interfaces of the superlattice, it is seen that the effective thermal resistance of the layers will depend on the heat flux. Thus, the concentration dependence of the transport coefficients plus the mobility of the defects lead to a strongly nonlinear behavior of heat transport, which may be used in some cases as a basis for thermal transistors
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