Periodic orbit bifurcations and scattering time delay fluctuations

We study fluctuations of the Wigner time delay for open (scattering) systems which exhibit mixed dynamics in the classical limit. It is shown that in the semiclassical limit the time delay fluctuations have a distribution that differs markedly from those which describe fully chaotic (or strongly disordered) systems: their moments have a power law dependence on a semiclassical parameter, with exponents that are rational fractions. These exponents are obtained from bifurcating periodic orbits trapped in the system. They are universal in situations where sufficiently long orbits contribute. We illustrate the influence of bifurcations on the time delay numerically using an open quantum map.Comment: 9 pages, 3 figures, contribution to QMC200

Superscars in the LiNC=LiCN isomerization reaction

We demonstrate the existence of superscarring in the LiNC=LiCN isomerization reaction described by a realistic potential interaction in the range of readily attainable experimental energies. This phenomenon arises as the effect of two periodic orbits appearing "out of the blue"in a saddle--node bifurcation taking place in the dynamics of the system. Potential practical consequences of this superlocalization in the corresponding wave functions are also considered.Comment: 6 pages, 5 figures. to appear in EP

Optimal Trajectories for Near-Earth-Objects Using Solar Electric Propulsion (SEP) and Gravity Assisted Maneuver

The future interplanetary missions will probably use the conventional chemical rockets to leave the sphere of influence of the Earth, and solar electric propulsion (SEP) to accomplish the other maneuvers of the mission. In this work the optimization of interplanetary missions using solar electric propulsion and Gravity Assisted Maneuver to reduce the costs of the mission, is considered. The high specific impulse of electric propulsion makes a Gravity Assisted Maneuver 1 year after departure convenient. Missions for several Near Earth Asteroids will be considered. The analysis suggests criteria for the definition of initial solutions demanded for the process of optimization of trajectories. Trajectories for the asteroid 2002TC70 are analyzed. Direct trajectories, trajectories with 1 gravity assisted from the Earth and with 2 gravity assisted from the Earth and either Mars are present. An indirect optimization method will be used in the simulations

Potencial de uso de métricas de paisagem para relacionar a dinâmica de uso da terra com a qualidade da água: estudo de caso na região serrana do Estado do Rio de Janeiro.

A configuração de uma paisagem está relacionada à dinâmica do uso e cobertura da terra na qual ela se insere. Este fato afeta diretamente a sua estrutura e confere padrões espaciais aos fragmentos florestais, bem como aos usos predominantes da terra de uma determinada região. Essa configuração espacial reflete tanto nos processos naturais como a qualidade da água, quanto nos aspectos socioeconômicos associados. Por isso, faz-se necessário o entendimento dessa distribuição espacial; o que pode ser obtido a partir do cálculo de métricas de paisagem. No presente trabalho foram analisadas 16 métricas de paisagem em uma bacia de drenagem na região montanhosa do Rio de Janeiro, denominada Pito Aceso - afluente do Rio Grande, que por sua vez é afluente do Rio Paraíba do Sul. Posteriormente aos cálculos das métricas, foi realizada uma análise por componentes principais onde foi possível observar as métricas que se mostraram mais eficientes para evidenciar a estrutura da paisagem em análise. Como estudos da qualidade da água também foram realizados na bacia, a próxima etapa do trabalho será associar esses resultados aos resultados de qualidade da água, de forma a demonstrar a potencialidade do uso dessas análises para subsidiar o planejamento sustentável das paisagens bem como dos recursos hídricos

Impact of DM direct searches and the LHC analyses on branon phenomenology

Dark Matter direct detection experiments are able to exclude interesting parameter space regions of particle models which predict an important amount of thermal relics. We use recent data to constrain the branon model and to compute the region that is favored by CDMS measurements. Within this work, we also update present colliders constraints with new studies coming from the LHC. Despite the present low luminosity, it is remarkable that for heavy branons, CMS and ATLAS measurements are already more constraining than previous analyses performed with TEVATRON and LEP data.Comment: 17 pages, 2 figure

Semiclassical structure of chaotic resonance eigenfunctions

We study the resonance (or Gamow) eigenstates of open chaotic systems in the semiclassical limit, distinguishing between left and right eigenstates of the non-unitary quantum propagator, and also between short-lived and long-lived states. The long-lived left (right) eigenstates are shown to concentrate as $\hbar\to 0$ on the forward (backward) trapped set of the classical dynamics. The limit of a sequence of eigenstates $\{\psi(\hbar)\}_{\hbar\to 0}$ is found to exhibit a remarkably rich structure in phase space that depends on the corresponding limiting decay rate. These results are illustrated for the open baker map, for which the probability density in position space is observed to have self-similarity properties.Comment: 4 pages, 4 figures; some minor corrections, some changes in presentatio

Sistematização de metadados de parcelas permanentes.

Resumo

Mining Scientific Articles Powered by Machine Learning Techniques

Literature review is one of the most important phases of research. Scientists must identify the gaps and challenges about certain area and the scientific literature, as a result of the accumulation of knowledge, should provide enough information. The problem is where to find the best and most important articles that guarantees to ascertain the state of the art on that specific domain. A feasible literature review consists on locating, appraising, and synthesising the best empirical evidences in the pool of available publications, guided by one or more research questions. Nevertheless, it is not assured that searching interesting articles in electronic databases will retrieve the most relevant content. Indeed, the existent search engines try to recommend articles by only looking for the occurrences of given keywords. In fact, the relevance of a paper should depend on many other factors as adequacy to the theme, specific tools used or even the test strategy, making automatic recommendation of articles a challenging problem. Our approach allows researchers to browse huge article collections and quickly find the appropriate publications of particular interest by using machine learning techniques. The proposed solution automatically classifies and prioritises the relevance of scientific papers. Using previous samples manually classified by domain experts, we apply a Naive Bayes Classifier to get predicted articles from real world journal repositories such as IEEE Xplore or ACM Digital. Results suggest that our model can substantially recommend, classify and rank the most relevant articles of a particular scientific field of interest. In our experiments, we achieved 98.22% of accuracy in recommending articles that are present in an expert classification list, indicating a good prediction of relevance. The recommended papers worth, at least, the reading. We envisage to expand our model in order to accept user's filters and other inputs to improve predictions.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Departamento de Engenharia Informática Faculdade of Engenharia Universidade do PortoPIXEL Research Group UNEMATLIACC - Artificial Intelligence and Computing Science Laboratory Universidade do PortoLIAADDepartamento de Computação Faculdade de Ciências Universidade Estadual PaulistaDepartamento de Computação Faculdade de Ciências Universidade Estadual PaulistaCAPES: BEX 1338/14-

Manutenção do solo e água através de programas de pagamentos por serviços ambientais.

Atuando principalmente na conservação de áreas remanescentes das florestas, regeneração assistida em bacias hidrográficas e restauração florestal, os Projetos de Pagamento por Serviços Ambientais recompensam produtores por preservarem e restaurarem ecossistemas naturais, adotando um manejo sustentável, principalmente em florestas localizadas em áreas de nascentes, em matas ciliares e em áreas de captação. O monitoramento e a avaliação do progresso de programas de PSA são baseados em indicadores, que servem para identificar a atual situação e qualidade do que foi planejado, além de fornecer subsídios para a correção de possíveis problemas detectados. Definir precisamente o que será monitorado, quais os indicadores que serão utilizados e como comprovar o benefício das atividades é uma das maiores dificuldades dos sistemas de PSA. O trabalho apresenta os indicadores que são utilizados em programas de PSA, além de sugerir novos indicadores que auxiliem no monitoramento, visando uma maior eficiência dos programas