Immunization of Real Complex Communication Networks

Most communication networks are complex. In this paper, we address one of the fundamental problems we are facing nowadays, namely, how we can efficiently protect these networks. To this end, we study an immunization strategy and found that it works as good as targeted immunization, but using only local information about the network topology. Our findings are supported with numerical simulations of the Susceptible-Infected-Removed (SIR) model on top of real communication networks, where immune nodes are previously identified by a covering algorithm. The results provide useful hints in the way to design and deploying a digital immune system.Comment: 6 pages. To appear in the European Physical Journal B (2006

Seasonal decline in breeding performance of the Kelp Gull Larus dominicanus

The effects of timing of breeding on reproductive parameters of Kelp Gulls Larus dominicanus were studied in Patagonia, Argentina, during 1998 and 1999. Yearly and spatial variation in the study were assessed by sampling nests during two field seasons and in different areas within the colony, and accounted for variation with respect to breeding synchrony and breeding density. In both years and in three study areas, individuals laying earlier had higher hatching success, a larger number of chicks fledged, heavier chicks at one month and higher breeding success. Significant variation between study areas within the colony and between years was observed only for breeding success and number of chicks fledged. No effects of breeding synchrony on breeding parameters were detected. Timing of breeding, independent of study year and area, had no effect on either clutch size or egg size. Our results document for the first time the seasonal decline in breeding performance in the Kelp Gull, a species widely distributed in the southern hemisphere.Fil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Moreno, Juan. Consejo Superior de Investigaciones Científicas; EspañaFil: Potti Sánchez, Jaime. Consejo Superior de Investigaciones Científicas; Españ

Capital adequacy tests and limited liability of financial institutions

The theory of acceptance sets and their associated risk measures plays a key role in the design of capital adequacy tests. The objective of this paper is to investigate, in the context of bounded financial positions, the class of surplus-invariant acceptance sets. These are characterized by the fact that acceptability does not depend on the positive part, or surplus, of a capital position. We argue that surplus invariance is a reasonable requirement from a regulatory perspective, because it focuses on the interests of liability holders of a financial institution. We provide a dual characterization of surplus-invariant, convex acceptance sets, and show that the combination of surplus invariance and coherence leads to a narrow range of capital adequacy tests, essentially limited to scenario-based tests. Finally, we emphasize the advantages of dealing with surplus-invariant acceptance sets as the primary object rather than directly with risk measures, such as loss-based and excess-invariant risk measures, which have been recently studied by Cont, Deguest, and He (2013) and by Staum (2013), respectively

Dos años de Cumbres del G-20: adagio spiccato

La cumbre de Seúl del G-20 avanza lentamente en la reforma financiera global, la reforma interna del FMI y el establecimiento de una nueva agenda para el desarrollo. Tras dos años de cumbres de Jefes de Estado y de Gobierno, el G-20 está reformando lentamente y a saltos el Orden Económico Internacional. En Seúl llegan tres nuevos impulsos: parte de la reforma financiera, la reforma de gobernabilidad del FMI y una agenda para el desarrollo. En el lado del debe, se posponen una vez más –aunque con renovado impulso para 2011– la coordinación de políticas macroeconómicas para corregir los desequilibrios globales y la resolución de la ronda de Doha de la OMC

The IMF Getting what it Needs in (as) the Aftermath of the Crisis

Since 2009, the IMF has profoundly transformed all of its major policies in governance, surveillance, lending, and resources; leading to an institutional metamorphosis. This work looks at the fundamental changes in Fund´s main policies focusing on two broad questions: (i) what has been done?, placing into context the magnitude and nature of the policy changes; and, specially, (ii) what more can be done?, following a positive approach on the additional reforms that can be pursued, taking into account the current context of reform fatigue and the state of the debate within the IMFDesde 2009, el FMI ha transformado profundamente todas sus principales políticas de gobernanza, vigilancia, préstamos y recursos; dando lugar a una metamorfosis institucional. Este trabajo analiza los cambios en las principales políticas del Fondo centrándose en dos grandes preguntas: (i) ¿Qué reformas se han llevado a cabo?, poniendo en contexto la magnitud y la naturaleza de las reformas acometidas; y, sobre todo, (ii) ¿qué más se puede hacer?, siguiendo un enfoque positivo sobre las reformas adicionales que pueden impulsarse, teniendo en cuenta el actual contexto de fatiga reformista y el estado del debate en el seno del FMI