La actual crisis financiera y los Hedge Funds

La crisis inmobiliaria y financiera que se inició en EE.UU. en 2007 está teniendo consecuencias importantes en otros países. Inicialmente se atribuyó a los “hedge funds”, un tipo de inversor institucional no regulado, con fuerte incidencia en los mercados financieros. En el trabajo se expone que la crisis es, fundamentalmente, una crisis originada en el sector regulado. Los bancos e “investment banks” crearon vehículos especiales de inversión para sacar de sus balances deudas por ellos estructuradas. La falta de liquidez y de financiación ha hecho necesario que volvieran a asumir buena parte de ellas. El origen de la crisis no es un problema de falta de regulación, sino de una supervisión inadecuada de la regulación existente. ____________________________________________The U.S. housing and financial crisis of 2007 is having far-reaching repercussions in other countries. At the beginning, the crisis was attributed to hedge funds, non-regulated institutional investors with a strong influence in financial markets. The authors hold that the crisis arose from the regulated sector. Banks and investment banks set up special investment vehicles to take out of their balance-sheets debts they have structured. The scarcity of liquidity and financing made it necessary that they assume again a considerable amount of it. At the starting point of the crisis there was not a problem of non-regulation but of inadequate supervision of the existing regulation

Notícia de les darreres Converses filològiques de Fabra

Jordi Mir i Joan Solà editen i contextualitzen una de les converses filològiques de Pompeu Fabra que no foren recollides en l'edició posterior. Es tracta, concretament, de l'editada al diari 'La Humanitat' (després de l'etapa de 'La Publicitat') el 15 d'octubre del 1946. Fabra hi corregeix calcs i manlleus del castellà

El sistema monetario internacional y sus perspectivas de futuro

Editada en la Fundación Empresa PúblicaEste artículo parte de analizar la evolución del sistema monetario internacional desde la introducción de los tipos de cambio flotantes en 1973 hasta la actualidad y la controversia a que ha dado lugar el comportamiento del régimen de flexibilidad cambiaría, así como la conveniencia o no de establecer un sistema de tipos de cambio más estable. Después de hacer referencia a algunas de las propuestas que se han formulado para dotar de más estabilidad al sistema, se analiza la influencia de la mayor movilidad de los capitales y las enseñanzas que en este sentido puede ofrecer la reciente crisis del Sistema Monetario Europeo.This article analyses the evolution of the international monetary system from the introduction of floating exchange rates in 1973 to the present. It also dwells on the controversy over the results of a flexible exchange rate system versus a fíxed exchange regime. Later it studies the proposals put forward for the stability of the system, the influence of capital movements and the recent events of the crisis of the European Monetary System.Publicad

Approximation-Refinement Testing of Compute-Intensive Cyber-Physical Models: An Approach Based on System Identification

Black-box testing has been extensively applied to test models of Cyber-Physical systems (CPS) since these models are not often amenable to static and symbolic testing and verification. Black-box testing, however, requires to execute the model under test for a large number of candidate test inputs. This poses a challenge for a large and practically-important category of CPS models, known as compute-intensive CPS (CI-CPS) models, where a single simulation may take hours to complete. We propose a novel approach, namely ARIsTEO, to enable effective and efficient testing of CI-CPS models. Our approach embeds black-box testing into an iterative approximation-refinement loop. At the start, some sampled inputs and outputs of the CI-CPS model under test are used to generate a surrogate model that is faster to execute and can be subjected to black-box testing. Any failure-revealing test identified for the surrogate model is checked on the original model. If spurious, the test results are used to refine the surrogate model to be tested again. Otherwise, the test reveals a valid failure. We evaluated ARIsTEO by comparing it with S-Taliro, an open-source and industry-strength tool for testing CPS models. Our results, obtained based on five publicly-available CPS models, show that, on average, ARIsTEO is able to find 24% more requirements violations than S-Taliro and is 31% faster than S-Taliro in finding those violations. We further assessed the effectiveness and efficiency of ARIsTEO on a large industrial case study from the satellite domain. In contrast to S-Taliro, ARIsTEO successfully tested two different versions of this model and could identify three requirements violations, requiring four hours, on average, for each violation

Optimización de una Técnica Espectrofotométrica de Medida de Ecotoxicidad en Algas por Microtitulaciones

Ante la problemática de la gran presencia de fármacos tanto de uso humano como veterinario en el medio ambiente, surge la necesidad de evaluar el riesgo ambiental de estos compuestos en la cadena trófica. Para ello se requiere el desarrollo de estudios ecotoxicológicos en diferentes especies bioindicadoras de la misma, como son las algas, las daphnias y los peces. Se ha llevado a cabo la puesta a punto, mediante microtitulaciones, de una técnica espectrofotométrica para medir la inhibición de crecimiento en algas Selenastrum capricornutum ante la presencia de medicamentos en el medio acuático con el objetivo de minimizar gastos en material y tiempo. Los resultados preliminares de este estudio permiten obtener datos de ecotoxicidad de fármacos con fiabilidad y se ha demostrado que la modificación de la técnica es reproducible

Schedulability Analysis of Real-Time Systems with Uncertain Worst-Case Execution Times

Schedulability analysis is about determining whether a given set of real-time software tasks are schedulable, i.e., whether task executions always complete before their specified deadlines. It is an important activity at both early design and late development stages of real-time systems. Schedulability analysis requires as input the estimated worst-case execution times (WCET) for software tasks. However, in practice, engineers often cannot provide precise point WCET estimates and prefer to provide plausible WCET ranges. Given a set of real-time tasks with such ranges, we provide an automated technique to determine for what WCET values the system is likely to meet its deadlines, and hence operate safely. Our approach combines a search algorithm for generating worst-case scheduling scenarios with polynomial logistic regression for inferring safe WCET ranges. We evaluated our approach by applying it to a satellite on-board system. Our approach efficiently and accurately estimates safe WCET ranges within which deadlines are likely to be satisfied with high confidence

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data