Decoding of Convolutional Codes over the Erasure Channel

In this paper we study the decoding capabilities of convolutional codes over the erasure channel. Of special interest will be maximum distance profile (MDP) convolutional codes. These are codes which have a maximum possible column distance increase. We show how this strong minimum distance condition of MDP convolutional codes help us to solve error situations that maximum distance separable (MDS) block codes fail to solve. Towards this goal, we define two subclasses of MDP codes: reverse-MDP convolutional codes and complete-MDP convolutional codes. Reverse-MDP codes have the capability to recover a maximum number of erasures using an algorithm which runs backward in time. Complete-MDP convolutional codes are both MDP and reverse-MDP codes. They are capable to recover the state of the decoder under the mildest condition. We show that complete-MDP convolutional codes perform in certain sense better than MDS block codes of the same rate over the erasure channel.Comment: 18 pages, 3 figures, to appear on IEEE Transactions on Information Theor

Decoding of MDP Convolutional Codes over the Erasure Channel

This paper studies the decoding capabilities of maximum distance profile (MDP) convolutional codes over the erasure channel and compares them with the decoding capabilities of MDS block codes over the same channel. The erasure channel involving large alphabets is an important practical channel model when studying packet transmissions over a network, e.g, the Internet

Horizontal Accessibility: Novelties from new ceramic Pavements

Los bienes patrimoniales deben ser conservados pero muchos de ellos presentan barreras de acceso, lo que impide cumplir el derecho de las personas a acceder al patrimonio como parte fundamental de la cultura. Para ello son necesarios los productos y sistemas adecuados para garantizar un acceso seguro y confortable a los monumentos, de forma no discriminatoria, para todos los ciudadanos, y de forma compatible con el bien cultural y reversible, tanto en las fases de conservación, como en la de “explotación” del patrimonio existente. En este contexto se han desarrollado soluciones para la accesibilidad horizontal, consistentes en estructuras ligeras con pavimentos de gres porcelánico, que permiten incluir elementos de información y orientación sobre el bien patrimonial con un impacto reducido, mediante la utilización de técnicas de impresión digital sobre la superficie de las baldosas cerámicas. Un sistema que mejora la accesibilidad distinguiendo la intervención respecto del original gracias al acabado estético diferenciado y considerando: seguridad, accesibilidad y cargas asociadas al uso. Además, se han incluido requisitos emocionales y funcionales de los usuarios, debido a que en un sistema de pavimentación deben considerarse especialmente los requisitos derivados de las diferentes formas de movilidad, marcha humana tanto normal como patológica, con sillas de ruedas, etc. Dichos requisitos se han definido teniendo especialmente en cuenta al usuario. El presente artículo desarrollado en el marco del proyecto PATRAC2 presenta los requisitos obtenidos y la definición de los sistemas de pavimentación mediante el caso de estudio de la Mezquita del Cristo de la Luz en Toledo, donde se plantea una posible solución para la accesibilidad horizontal

Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011-2012 season in Spain, among population targeted for vaccination

Background: In Spain, the influenza vaccine effectiveness (VE) was estimated in the last three seasons using the observational study cycEVA conducted in the frame of the existing Spanish Influenza Sentinel Surveillance System. The objective of the study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza-like illness (ILI) among the target groups for vaccination in Spain in the 2011-2012 season. We also studied influenza VE in the early (weeks 52/2011-7/2012) and late (weeks 8-14/2012) phases of the epidemic and according to time since vaccination. Methods: Medically attended patients with ILI were systematically swabbed to collect information on exposure, laboratory outcome and confounding factors. Patients belonging to target groups for vaccination and who were swabbed 4 months, respectively, since vaccination. A decrease in VE with time since vaccination was only observed in individuals aged ≥ 65 years. Regarding the phase of the season, decreasing point estimates were only observed in the early phase, whereas very low or null estimates were obtained in the late phase for the shortest time interval. Conclusions: The 2011-2012 influenza vaccine showed a low-to-moderate protective effect against medically attended, laboratory-confirmed influenza in the target groups for vaccination, in a late season and with a limited match between the vaccine and circulating strains. The suggested decrease in influenza VE with time since vaccination was mostly observed in the elderly population. The decreasing protective effect of the vaccine in the late part of the season could be related to waning vaccine protection because no viral changes were identified throughout the season

Robust Optimization in Finance

Dissertação de Mestrado em Métodos Quantitativos em Finanças apresentada à Faculdade de Ciências e TecnologiaO propósito deste trabalho é consolidar o tema da otimização robusta. Como já sabemos, a otimização é uma área da matemática que visa encontrar o mínimo ou o máximo de uma função (função essa denominada de função objetivo), quando sujeita a restrições (restrições do problema) e, por sua vez, tenta resolver de forma eficiente problemas do mundo real. Contudo, muitos dos problemas reais possuem incertezas nos diversos parâmetros de entrada, tais como preços, custos, produção, etc. Daí a necessidade do aparecimento da otimização robusta, que é uma forma de tratamento de problemas de otimização com incerteza/dúvida nos parâmetros. Neste trabalho pretende-se fazer uma breve introdução a este tema (otimização robusta), considerando vários conjuntos de incerteza (nomeadamente: discreto, convexo, sob a forma de intervalo e elipsoidal) e fazendo referência a alguns problemas de otimização em finanças. A par disto, e como já era de esperar, a robustez surge em diferentes circunstâncias que dá origem a vários tipos de robustez existentes (robustez de restrições, objetiva, relativa e uma última abordada neste trabalho a robustez de otimização ajustável), tendo desenvolvido alguns deles nesta tese, com base na teoria e posteriormente exemplificado com exemplos de carácter simples. Por fim, apresentam-se resultados computacionais (resultados esses provenientes de programas computacionais realizados em Matlab com várias simulações) que mostram a importância da otimização robusta num contexto prático de seleção robusta de carteiras em múltiplos períodos.The purpose of this paper is to consolidate the topic of robust optimization.As we already know, optimization is an area of ​​mathematics that seeks to find the minimum or maximum of a function (function called the objective function), when constrained (problem constraints) and, in turn, attempts to efficiently solve real-world problems. However, many of the real problems have uncertainties in the various input parameters, such as prices, costs, production, etc. Hence the need for the appearance of robust optimization, which is a way of handling optimization problems with uncertainty in the parameters. In this work we intend to make a brief introduction to this topic (robust optimization), considering several sets of uncertainty (namely: discrete, convex, in the form of interval and ellipsoidal) and referring to some optimization problems in finance. In addition, and as might be expected, robustness arises in different circumstances that gives rise to several types of robustness (robustness of constraints, objective, relative and one last addressed in this work the robustness of adjustable optimization), having developed some of them in this thesis, based on theory and subsequently exemplified with examples of simple character. Finally, we present computational results (results from computer programs carried out in Matlab with various simulations) that show the importance of robust optimization in a practical context of robust selection of portfolios in multiple periods, comparing with different approaches