C4.5: um recurso para geração de árvores de decisão.

O Sistema de Indução C4.5. Requerimentos-chave para a utilização do software. Um exemplo ilustrativo. Algumas dicas de uso.bitstream/CNPTIA/9200/1/INSTRTECNICAS7int.pdfAcesso em: 30 maio 2008

Emergence of Hierarchy on a Network of Complementary Agents

Complementarity is one of the main features underlying the interactions in biological and biochemical systems. Inspired by those systems we propose a model for the dynamical evolution of a system composed by agents that interact due to their complementary attributes rather than their similarities. Each agent is represented by a bit-string and has an activity associated to it; the coupling among complementary peers depends on their activity. The connectivity of the system changes in time respecting the constraint of complementarity. We observe the formation of a network of active agents whose stability depends on the rate at which activity diffuses in the system. The model exhibits a non-equilibrium phase transition between the ordered phase, where a stable network is generated, and a disordered phase characterized by the absence of correlation among the agents. The ordered phase exhibits multi-modal distributions of connectivity and activity, indicating a hierarchy of interaction among different populations characterized by different degrees of activity. This model may be used to study the hierarchy observed in social organizations as well as in business and other networks.Comment: 13 pages, 4 figures, submitte

Probing quantum fluctuation theorems in engineered reservoirs

Fluctuation Theorems are central in stochastic thermodynamics, as they allow for quantifying the irreversibility of single trajectories. Although they have been experimentally checked in the classical regime, a practical demonstration in the framework of quantum open systems is still to come. Here we propose a realistic platform to probe fluctuation theorems in the quantum regime. It is based on an effective two-level system coupled to an engineered reservoir, that enables the detection of the photons emitted and absorbed by the system. When the system is coherently driven, a measurable quantum component in the entropy production is evidenced. We quantify the error due to photon detection inefficiency, and show that the missing information can be efficiently corrected, based solely on the detected events. Our findings provide new insights into how the quantum character of a physical system impacts its thermodynamic evolution.Comment: 9 pages, 4 figure

Tecnologias sociais, TICs e educação: pilares para a construção da Tecnopedia Social Rural - TeSoRu.

O artigo apresenta uma proposta de modelo conceitual para formar uma rede de conhecimento integrada à pesquisa, extensão e ensino visando atender aos agricultores familiares, denominada de Tecnopedia Social Rural (TeSoRu) usando as Tecnologias da Informação e Comunicação (TICs) como instrumento mediador. A partir da ênfase na construção, aperfeiçoamento, captura e disseminação de experiências, saberes, informações e conhecimentos, inerentes às diversas coletividades que integram a rede e das potencialidades inseridas nas TICs, espera-se que a TeSoRu sirva como um canal dinâmico de comunicação e institucionalização de novas inteligibilidades subsidiando a inclusão social e digital no espaço rural .SBIE 2010

Reflexões sobre a implantação de um programa de TI-Verde para a Embrapa: bases conceituais e metodológicas.

A Embrapa Informática Agropecuária, neste documento, oferece sua contribuição trazendo à tona uma reflexão sobre a implementação de um Programa de TI-Verde coorporativo. A ideia central é introduzir essa problemática no escopo das iniciativas de gestão ambiental que vêm sendo exercitadas pela empresa de maneira que sirva como um ponto de partida para se ampliar discussões sobre como a empresa pode produzir uma gestão sustentável dos recursos tecnológicos da informação.bitstream/item/11848/1/doc86.pd

Survival-extinction phase transition in a bit-string population with mutation

A bit-string model for the evolution of a population of haploid organisms, subject to competition, reproduction with mutation and selection is studied, using mean field theory and Monte Carlo simulations. We show that, depending on environmental flexibility and genetic variability, the model exhibits a phase transtion between extinction and survival. The mean-field theory describes the infinite-size limit, while simulations are used to study quasi-stationary properties.Comment: 11 pages, 5 figure

Immunization and Aging: a Learning Process in the Immune Network

The immune system can be thought as a complex network of different interacting elements. A cellular automaton, defined in shape-space, was recently shown to exhibit self-regulation and complex behavior and is, therefore, a good candidate to model the immune system. Using this model to simulate a real immune system we find good agreement with recent experiments on mice. The model exhibits the experimentally observed refractory behavior of the immune system under multiple antigen presentations as well as loss of its plasticity caused by aging.Comment: 4 latex pages, 3 postscript figures attached. To be published in Physical Review Letters (Tentatively scheduled for 5th Oct. issue

Efeito do cozimento e mercaptoetanol na proteínas do glúten de trigo.

Neste trabalho o glúten de trigo foi submetido a ação de mercaptoetanol e ao cozimento com o intuito de se quantificar as alterações causadas por estes processos nas concentrações das estruturas secundárias de suas proteínas componentes.bitstream/CNPDIA/8018/1/BPD02_2002.pd

On the structure of the neritic suprabenthic communities from the Portuguese continental margin

This work presents the investigations made on the neritic suprabenthic communities of the Portuguese margin (continental shelf and upper slope) exposed to seasonal upwelling. These communities were sampled during the AVEIRO-94 cruise at 5 sites located along an E-W bathymetric transect from 21 to 299 m depth using a suprabenthic sled with superposed nets. In the 0 to 100 cm water layer, the total densities ranged from 700.2 to 13591.7 ind. 100m(-2). During daytime, the motile fauna was mainly concentrated within the 0 to 50 cm water layer (76.2 to 97.2% of the total abundance). The night-time sample at the shallower site showed a more even distribution of the fauna in the near-bottom water layers (nocturnal migratory behaviour of some motile species). The Shannon diversity (H') values ranged from 1.84 to 3.54 for the shelf sites and increased at the upper slope site (4.15). Mysids and amphipods were generally dominant except for at the middle part of the shelf where the latter was replaced by euphausiids. The suprabenthic fauna off Aveiro was compared with similar data from the same bathymetric sampling levels off Arcachon (Bay of Biscay). Multivariate analysis showed that differences in faunal composition between the 2 geographic areas were smaller than depth-related variations within geographic areas. The results were discussed in relation to other suprabenthic communities from the northeastern Atlantic.Programa de Cooperação Oceanológica Luso-FrancesaJNICT/Embaixada de FrançaFrench CIRMAT-CNR