Rationality and Brauer group of a moduli space of framed bundles

We prove that the moduli spaces of framed bundles over a smooth projective curve are rational. We compute the Brauer group of these moduli spaces to be zero under some assumption on the stability parameter.Comment: 7 pages, to appear in Tbilisi Math. J; v2. reference adde

The Effect of the Exchange Rates on Investment in Mexican Manufacturing Industry

This paper, considering revenue and cost exposure channels, investigates the effects of exchange rate behaviour on fixed capital investment in Mexican manufacturing sector over 1994-2002. We find that i) currency depreciation has a positive (negative) effect on fixed investment through the export (import) channel; ii) exchange rate volatility impacts mostly export oriented sectors ; iii) the sensitivity of investment to exchange rate movements is stronger in non-durable goods sectors and industries with low mark-up ratios.Exchange rate volatility ; investment ; external exposure ; market structure

Time-Delayed transfer functions simulations for LMXBs

Recent works (Steeghs & Casares 2002, Casares et al. 2003, Hynes et al. 2003) have demonstrated that Bowen flourescence is a very efficient tracer of the companion star in LMXBs. We present a numerical code to simulate time-delayed transfer functions in LMXBs, specific to the case of reprocessing in emission lines. The code is also able to obtain geometrical and binary parameters by fitting observed (X-ray + optical) light curves using simulated annealing methods. In this work we present the geometrical model for the companion star and the analytical model for the disc and show synthetic time-delay transfer functions for different orbital phases and system parameters.Comment: Contribution presented at the conference "Interacting Binaries: Accretion, Evolution and Outcomes", held in Cefalu, Sicily (Italy) in July 2004. To be published by AIP (American Institute of Physics), eds. L. A. Antonelli, L. Burderi, F. D'Antona, T. Di Salvo, G.L. Israel, L. Piersanti, O. Straniero, A. Tornambe. 4 pages, 4 figure

Dynamics of soliton-like solutions for slowly varying, generalized gKdV equations: refraction vs. reflection

In this work we continue the description of soliton-like solutions of some slowly varying, subcritical gKdV equations. In this opportunity we describe, almost completely, the allowed behaviors: either the soliton is refracted, or it is reflected by the potential, depending on its initial energy. This last result describes a new type of soliton-like solution for gKdV equations, also present in the NLS case. Moreover, we prove that the solution is not pure at infinity, unlike the standard gKdV soliton.Comment: 51 pages, submitte

Optimal scheme for estimating a pure qubit state via local measurements

We present the optimal scheme for estimating a pure qubit state by means of local measurements on N identical copies. We give explicit examples for low N. For large N, we show that the fidelity saturates the collective measurement bound up to order 1/N. When the signal state lays on a meridian of the Bloch sphere, we show that this can be achieved without classical communication.Comment: Version to appear in PRL (minor changes, title changed

Estudi de la viabilitat econòmica d’un vehicle de transport basat en una pila de combustible polimèrica (PEMFC)

Treballs Finals del Màster d’Energies Renovables i Sostenibilitat Energètica, Facultat de Física, Universitat de Barcelona, Curs: 2013-2014, Tutor: Pere Lluís CabotDes de principis del S. XIX, la humanitat ha anat incrementant el consum de combustibles fòssils destinats al funcionament de la indústria en general i més concretament al transport, sector que consumeix aproximadament el 40% de l’energia primària generada (IDAE, 2014) (WWF, 2014). Aquest consum sempre ha estat estretament lligat a l’extracció i producció de manera exponencial de carbó, petroli i gas natural (BP, 2013) demostrant així que el model energètic actual té una dependència gairebé total de les fonts d’energia no renovables i va en augment amb una taxa mitjana de creixement d’un 2% (ICAEN, 2014). Aquesta dependència comporta certs problemes que es van agreujant amb el temps. Un dels problemes més tangibles és el fet que amb les tecnologies i sistemes d’obtenció de combustibles fòssils actuals, les reserves són finites i, a més a més, en la dècada actual s’ha arribat al pic màxim de producció fent que el preu del petroli s’hagi disparat a valors inesperats i segueixi incrementant any rere any (Peak Oil Association)..