Space-Time diversity for NLOS mitigation in TDOA-based positioning systems

This paper studies the potential impact of using space-Time information in the mitigation of the Non-LineOf-Sight condition in mobile subscriber's positioning systems. First of all, this work discusses the positioning problem based on measures of Time Differences Of Arrival departing from a more exact characterization of the signal statistics and including some geometrical restrictions to achieve an improved accurate. Furthermore, a novel approach that integrates signal propagation characteristics to information provided by a suitable timing estimation model based on Cramer Rao Bound for a Rayleigh-fading channel, when antenna arrays are used at the receiver and when a set ofchannel vector estimates are available, has been introduced to study the positive benefits of space-Time diversity. These approaches are evaluated within a realistic simulation scenario.Peer ReviewedPostprint (published version

Capital Inflows, Exchange Rate Flexibility, and Credit Booms

The prospects of expansionary monetary policies in the advanced countries for the foreseeable future have renewed the debate over policy options to cope with large capital inflows that are, at least partly, driven by low interest rates in the financial centers. Historically, capital flow bonanzas have often fueled sharp credit expansions in advanced and emerging market economies alike. Focusing primarily on emerging markets, we analyze the impact of exchange rate flexibility on credit markets during periods of large capital inflows. We show that credit grows more rapidly and its composition tilts to foreign currency in economies with less flexible exchange rate regimes, and that these results are not explained entirely by the fact that the latter attract more capital inflows than economies with more flexible regimes. Our findings thus suggest countries with less flexible exchange rate regimes may stand to benefit the most from regulatory policies that reduce banks’ incentives to tap external markets and to lend/borrow in foreign currency; these policies include marginal reserve requirements on foreign lending, currency-dependent liquidity requirements, and higher capital requirement and/or dynamic provisioning on foreign exchange loans.

Minimal hermitian matrices with fixed entries outside the diagonal

We survey some results concerning the problem of finding the complex hermitian matrix or matrices of least supremum norm with variable diagonal. Some qualitative general results are given and more specific descriptions are shown for the 3 x 3 case. We also comment some results and examples concerning this approximation problem.Fil: Andruchow, Esteban. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Mata Lorenzo, Luis E.. Universidad Simón Bolívar; VenezuelaFil: Mendoza, Alberto.. Universidad Simón Bolívar; VenezuelaFil: Recht, Lázaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universidad Simón Bolívar; VenezuelaFil: Varela, Alejandro. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Cosmological Magnetic Fields from Gauge-Mediated Supersymmetry-Breaking Models

We study the generation of primordial magnetic fields, coherent over cosmologically interesting scales, by gravitational creation of charged scalar particles during the reheating period. We show that magnetic fields consistent with those detected by observation may obtained if the particle mean life \tau_s is in the range 10^{-14} sec \leq \tau_s \leq 10{-7} sec. We apply this mechanism to minimal gauge mediated supersymmetry-breaking models, in the case in which the lightest stau \tilde\tau_1 is the next-to-lightest supersymmetric particle. We show that, for a large range of phenomenologically acceptable values of the supersymmetry-breaking scale \sqrt{F}, the generated primordial magnetic field can be strong enough to seed the galactic dynamo.Comment: 12 pages, Latex. Final version accepted for publication in Phys. Lett.

Estructura informativa y derecho a comunicar

In recent years the notion of a new right has become widespread: the right to communicate. The conceptual framework of tbis new right is based upon a particular distinction ---one among many- of the notions of information and of communication. We may speak of information when messages flow in only one direction, without answer or reciprocity. Communication, on the other hand, presupposes interactiong and exchange on an equal ground. Starting from this distinction one sector of the experts in the communications field indicate that we can not speak of communication -but rather only of information- when we refer to modern means of diffusion. The fact that nowadays we speak of «a new world order of information and 01 communication» and not of «an international order of information» reveals to what extent this interpretation has become widespread. The new right to communication is presented as yet another step within a process whose stages were freedom of speech, opinion, of the press, of information and, more recently, the right to information, which now would become encompassed within the new right. We are not dealing with an attempt to do away with rights already achieved, but rather to situate them which emphasizes -for aIl- the active role of the right to informo The first allusion to this right was made by n'ARcY in 1969. From that point on, a number of work groups have been set up -the most renown being the group operating out of the University of Hawaiito develop this concepto International organizations such as the International Broadcast Institute, UNESCO and the Asian Mass Communication and Information Centre have dealt with it also. The Report of the International Commission for the Study of the Problems of Communications in the World (McBride Commission) contains numerous aIlusions to this right, even though it recognizes .that the present formulation is yet imperfecto The author of this paper considers that the most adequate treatment of the eventual basic human right to communicate is the one carried out by Desmond FIS H ER, with whom he is in agreement and shares bis criterion that we are dealing with a right that belongs to each individual first and then, as a derivation, to groups or collectivities at any leve!. FISHER'S schéma, which puts forth a hierarchical framework between the basic right, derived liberties and particular rights with respect to the exercise of human communication, is adequately articulated and sheds light upon legitimate limitations which could become established, motivated by the protection of the rights of others. In his final observations, the author sta tes that in spite of the distinction between information and communication, which in a certain sense may be considered arbitrary, the new concept could be of great utility, insofar as it signifies an attempt to avercome pure Liberalism, at the same time that, when considered as a fundamental human right, it constitutes a decisive rejection of the systems that have adopted the Soviet model or any other dictatorial varia ton of that model