Random perturbations of non-uniformly expanding maps

We give both sufficient conditions and necessary conditions for the stochastic stability of non-uniformly expanding maps either with or without critical sets. We also show that the number of probability measures describing the statistical asymptotic behaviour of random orbits is bounded by the number of SRB measures if the noise level is small enough. As an application of these results we prove the stochastic stability of certain classes of non-uniformly expanding maps introduced in \cite{V} and \cite{ABV}.Comment: 44 pages, 2 figure

O Impacto da Iniciativa de Integração de Infraestrutura Regional Sul-Americana (IIRSA) na qualidade de vida do Eixo Amazônico: um Estudo de Caso da Rodovia Tarapoto - Yurimaguas

Orientador: FABIO BORGESA história da América Latina possui diversas iniciativas de integração. Porém a Iniciativa de Integração de Infraestrutura Regional Sul-Americana (IIRSA) se apresentou como inédita, primeiro na composição dos participantes, ao ser a primeira a contar com 12 países sul-americanos, mas também em sua proposta inovadora de incorporar novos temas à integração regional a partir de obras de infraestrutura transnacional. Conforme consta em suas diretrizes, proposta no documento de fundação, a IIRSA pretende valorizar a dimensão ambiental e social dos projetos, melhorando a qualidade de vida da população local. Considerando isso, tem-se por objetivo principal dessa dissertação expor os impactos deste empreendimento na qualidade de vida dos moradores próximos às obras. Para alcançar o objetivo de pesquisa, utilizou-se a revisão bibliográfica de temas correlatos e análise das opiniões de habitantes próximos à obra eleita para o estudo de caso, colhidas através de entrevistas seguindo roteiro de perguntas abertas. A hipótese central deste trabalho, de que a qualidade de vida da população amazônica é impactada negativamente pelas obras da IIRSA na região, foi parcialmente confirmada. Ocorreram tanto transformações positivas quanto negativas. Entretanto, o entendimento da população sobre a definição de qualidade de vida se mostrou distante do perseguido pela IIRSA. Conclui-se, portanto, que a principal omissão da IIRSA foi o fraco diálogo com os habitantes da região, o que poderia terevitado inúmeros problemas relatados

Antioxidants of natural plant origins: from sources to food industry applications

ReviewIn recent years, great interest has been focused on using natural antioxidants in food products, due to studies indicating possible adverse effects that may be related to the consumption of synthetic antioxidants. A variety of plant materials are known to be natural sources of antioxidants, such as herbs, spices, seeds, fruits and vegetables. The interest in these natural components is not only due to their biological value, but also to their economic impact, as most of them may be extracted from food by-products and under-exploited plant species. This article provides an overview of current knowledge on natural antioxidants: their sources, extraction methods and stabilization processes. In addition, recent studies on their applications in the food industry are also addressed; namely, as preservatives in different food products and in active films for packaging purposes and edible coatingsinfo:eu-repo/semantics/publishedVersio

Knowledge discovery methodology for medical reports

Medical reports contain valuable information, not only for the patient that waits for the results but also the latent knowledge that is possible to extract from them. The recent introduction of standard structured formats like the Digital Imaging and Communications in Medicine Structured Report and the Clinical Document Architecture Health Level Seven provide an efficient generation, distribution, and management mechanism. Also, they provide an intuitive and effective manner of information representation, unlike the traditional plain text format. In this paper we present a knowledge discovery methodology for structured report interchange based on plain text medical reports using YALE, a leading open-source data mining tool and Open-ESB platform that provides conversion, parsing, different protocols and message formats interchange capabilities.Centro de Imagiologia da Trindade (CIT

Does Speculation Affect Oil Price Volatiliy?

O objetivo do presente estudo é tentar perceber se a atividade especulativa é o fator principal na repentina subida de preços do crude no spot market, especialmente no mais recente episódio especulativo que ocorreu entre 2003 e a primeira metade de 2008. A base do nosso estudo assenta num modelo já existente de vectores autoregressivos que foi proposto por Kilian e Murphy (2014); um modelo estrutural do mercado global do crude que permite uma análise de choques de procura e oferta e também choques especulativos. A originalidade do modelo apresentado nesta dissertação, relativamente ao daqueles autores, reside na introdução de um componente especulativo para medir os spreads usando contratos de futuros do crude. Com o output do modelo estrutural apresentado conseguimos excluir a teoria da especulação como fator na subida do preço do crude; no entanto, os nossos resultados sugerem que a subida se deve a um aumento na procura conduzido por um crescimento económico inesperado na economia global. As conclusões deste estudo permitem confirmar as de outras obras literárias da mesma natureza e revelam a importância dos futuros enquanto instrumentos preditivo

Hyperbolic times: frequency versus integrability

We consider dynamical systems on compact manifolds, which are local diffeomorphisms outside an exceptional set (a compact submanifold). We are interested in analyzing the relation between the integrability (with respect to Lebesgue measure) of the first hyperbolic time map and the existence of positive frequency of hyperbolic times. We show that some (strong) integrability of the first hyperbolic time map implies the existence of a positive Lebesgue measure subset of points with positive frequency of hyperbolic times. We also present an example of a map with positive frequency of hyperbolic times at Lebesgue almost every point but whose first hyperbolic time map is not integrable with respect to the Lebesgue measure.Comment: 18 pages, 1 figur

Femtosecond laser ablation of dentin

The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm(-2)) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 +/- 0.2 J cm(-2) and the ablation rate achieved in the range 1 to 2 mu m/pulse for an average fluence of 3 J cm(-2). The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the beta-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material