K-41(n, gamma)K-42 thermal and resonance integral cross section measurements

We measured the K-41 thermal neutron absorption and resonance integral cross sections after the irradiation of KNO3 samples near the core of the IEA-R1 IPEN pool-type research reactor. Bare and cadmium-covered targets were irradiated in pairs with Au-Al alloy flux-monitors. The residual activities were measured by gamma-ray spectroscopy with a HPGe detector, with special care to avoid the K-42 decay beta(-) emission effects on the spectra. The gamma-ray self-absorption was corrected with the help of MCNP simulations. We applied the Westcott formalism in the average neutron flux determination and calculated the depression coefficients for thermal and epithermal neutrons due to the sample thickness with analytical approximations. We obtained 1.57(4) and 1.02(4) b, for thermal and resonance integral cross sections, respectively, with correlation coefficient equal to 0.39.

A graph-theoretical approach in brain functional networks. Possible implications in EEG studies

Abstract Background Recently, it was realized that the functional connectivity networks estimated from actual brain-imaging technologies (MEG, fMRI and EEG) can be analyzed by means of the graph theory, that is a mathematical representation of a network, which is essentially reduced to nodes and connections between them. Methods We used high-resolution EEG technology to enhance the poor spatial information of the EEG activity on the scalp and it gives a measure of the electrical activity on the cortical surface. Afterwards, we used the Directed Transfer Function (DTF) that is a multivariate spectral measure for the estimation of the directional influences between any given pair of channels in a multivariate dataset. Finally, a graph theoretical approach was used to model the brain networks as graphs. These methods were used to analyze the structure of cortical connectivity during the attempt to move a paralyzed limb in a group (N=5) of spinal cord injured patients and during the movement execution in a group (N=5) of healthy subjects. Results Analysis performed on the cortical networks estimated from the group of normal and SCI patients revealed that both groups present few nodes with a high out-degree value (i.e. outgoing links). This property is valid in the networks estimated for all the frequency bands investigated. In particular, cingulate motor areas (CMAs) ROIs act as ‘‘hubs’’ for the outflow of information in both groups, SCI and healthy. Results also suggest that spinal cord injuries affect the functional architecture of the cortical network sub-serving the volition of motor acts mainly in its local feature property. In particular, a higher local efficiency El can be observed in the SCI patients for three frequency bands, theta (3-6 Hz), alpha (7-12 Hz) and beta (13-29 Hz). By taking into account all the possible pathways between different ROI couples, we were able to separate clearly the network properties of the SCI group from the CTRL group. In particular, we report a sort of compensatory mechanism in the SCI patients for the Theta (3-6 Hz) frequency band, indicating a higher level of “activation” Ω within the cortical network during the motor task. The activation index is directly related to diffusion, a type of dynamics that underlies several biological systems including possible spreading of neuronal activation across several cortical regions. Conclusions The present study aims at demonstrating the possible applications of graph theoretical approaches in the analyses of brain functional connectivity from EEG signals. In particular, the methodological aspects of the i) cortical activity from scalp EEG signals, ii) functional connectivity estimations iii) graph theoretical indexes are emphasized in the present paper to show their impact in a real application.

Avaliação da qualidade tecnológica de snacks obtidos por extrusão de grão integral de amaranto ou de farinha de amaranto desengordurada e suas misturas com fubá de milho

Apesar dos benefícios nutricionais e de seu potencial como alimento funcional, o amaranto ainda é um alimento pouco difundido no Brasil. Para o aumento do consumo desta matéria-prima, preconiza-se a sua incorporação na formulação de produtos convencionais, como os snacks extrudados que vêm sendo elaborados com a farinha de amaranto desengordurada. Pouco tem sido pesquisado sobre a extrusão direta do grão integral de amaranto, o que permitiria eliminar as etapas de moagem e de desengorduramento. Assim, a pesquisa avaliou e comparou a qualidade tecnológica de snacks obtidos por extrusão de grão integral de amaranto e de farinha de amaranto desengordurada, e suas misturas com 25 e 50% de fubá de milho. Verificou-se que o teor de lipídeos presentes no grão de amaranto (8%) prejudicou a expansão e a textura dos extrudados. Mesmo com a adição de fubá de milho, os snacks extrudados à base de grão integral de amaranto foram rejeitados sensorialmente (aceitação global entre 3 e 4, numa escala hedônica estruturada de nove pontos), pois apresentaram baixa expansão, textura dura, cor escura e forte sabor residual. Já os snacks extrudados obtidos com farinha de amaranto desengordurada isoladamente e em combinação com fubá de milho apresentaram maior expansão, textura crocante e cor mais clara, e, por isso, maior aceitabilidade (aceitação global > 5). Conclui-se, nas condições do experimento, que não foi possível obter snacks extrudados à base de grãos de amaranto de boa aceitação e que a produção de snacks extrudados à base de farinha de amaranto desengordurada proporciona produtos com melhor aceitação por parte do consumidor.

Sharp estimates for eigenvalues of integral operators generated by dot product kernels on the sphere

We obtain explicit formulas for the eigenvalues of integral operators generated by continuous dot product kernels defined on the sphere via the usual gamma function. Using them, we present both, a procedure to describe sharp bounds for the eigenvalues and their asymptotic behavior near 0. We illustrate our results with examples, among them the integral operator generated by a Gaussian kernel. Finally, we sketch complex versions of our results to cover the cases when the sphere sits in a Hermitian space.

Un modelo integral de control interno en el contexto de la universidad pública española

Doctorado en Ciencias Económicas y Empresariales. Programa de Fundamentos de Contabilidad y Economía Financiera

Gestión integral en la Playa de Montaña Arena: Análisis y Diagnóstico preliminar

Máster Universitario en Gestión Costera

Análisis y utilidad de un SGID (Sistema de gestión integral de destino) como herramienta para la competitividad de un destino turístico: propuestas para la sensibilización de los diferentes agentes turísticos implicados

Programa de doctorado: Turismo y desarrollo sostenible.

Concepción integral y aplicación experimental de procesos de membranas en la reutilización de aguas depuradas

[ES] El estudio enfoca el manejo de los procesos de membranas en la regeneración de aguas residuales y su utilización. Se especifican criterios de reuso y reciclo de agua y su proyección con un estudio de los fundamentos teóricos de la tecnología de membranas y nos guía a la aplicación real. En el apartado práctico exponemos el diseño, ensamblaje y operación de la planta semiindustrial de 860 m3/d que se desarrolla a través de dos líneas de actuación con aplicación en el campo agrícola, conceptos de reconversión y reuso de unidades que han cumplido su ciclo de vida útil en función del factor económico que se ha aplicado. Obtención de ocho calidades de agua para diversas aplicaciones con sistemas de clarificación, filtración multicapa, microfiltración, ultrafiltración, ósmosis inversa, intercambio iónico, electrodesionización y desinfección U. violeta y cloro.