Optimal Cosmic-Ray Detection for Nondestructive Read Ramps

Cosmic rays are a known problem in astronomy, causing both loss of data and data inaccuracy. The problem becomes even more extreme when considering data from a high-radiation environment, such as in orbit around Earth or outside the Earth's magnetic field altogether, unprotected, as will be the case for the James Webb Space Telescope (JWST). For JWST, all the instruments employ nondestructive readout schemes. The most common of these will be "up the ramp" sampling, where the detector is read out regularly during the ramp. We study three methods to correct for cosmic rays in these ramps: a two-point difference method, a deviation from the fit method, and a y-intercept method. We apply these methods to simulated nondestructive read ramps with single-sample groups and varying combinations of flux, number of samples, number of cosmic rays, cosmic-ray location in the exposure, and cosmic-ray strength. We show that the y-intercept method is the optimal detection method in the read-noise-dominated regime, while both the y-intercept method and the two-point difference method are best in the photon-noise-dominated regime, with the latter requiring fewer computations.Comment: To be published in PASP. This paper is 12 pages long and includes 15 figure

On the quantumness of correlations in nuclear magnetic resonance

Nuclear Magnetic Resonance (NMR) was successfully employed to test several protocols and ideas in Quantum Information Science. In most of these implementations the existence of entanglement was ruled out. This fact introduced concerns and questions about the quantum nature of such bench tests. In this article we address some issues related to the non-classical aspects of NMR systems. We discuss some experiments where the quantum aspects of this system are supported by quantum correlations of separable states. Such quantumness, beyond the entanglement-separability paradigm, is revealed via a departure between the quantum and the classical versions of information theory. In this scenario, the concept of quantum discord seems to play an important role. We also present an experimental implementation of an analogous of the single-photon Mach-Zehnder interferometer employing two nuclear spins to encode the interferometric paths. This experiment illustrate how non-classical correlations of separable states may be used to simulate quantum dynamics. The results obtained are completely equivalent to the optical scenario, where entanglement (between two field modes) may be present

Breaking Cosmological Degeneracies in Galaxy Cluster Surveys with a Physical Model of Cluster Structure

Forthcoming large galaxy cluster surveys will yield tight constraints on cosmological models. It has been shown that in an idealized survey, containing > 10,000 clusters, statistical errors on dark energy and other cosmological parameters will be at the percent level. It has also been shown that through "self-calibration", parameters describing the mass-observable relation and cosmology can be simultaneously determined, though at a loss in accuracy by about an order of magnitude. Here we examine the utility of an alternative approach of self-calibration, in which a parametrized ab-initio physical model is used to compute cluster structure and the resulting mass-observable relations. As an example, we use a modified-entropy ("pre-heating") model of the intracluster medium, with the history and magnitude of entropy injection as unknown input parameters. Using a Fisher matrix approach, we evaluate the expected simultaneous statistical errors on cosmological and cluster model parameters. We study two types of surveys, in which a comparable number of clusters are identified either through their X-ray emission or through their integrated Sunyaev-Zel'dovich (SZ) effect. We find that compared to a phenomenological parametrization of the mass-observable relation, using our physical model yields significantly tighter constraints in both surveys, and offers substantially improved synergy when the two surveys are combined. These results suggest that parametrized physical models of cluster structure will be useful when extracting cosmological constraints from SZ and X-ray cluster surveys. (abridged)Comment: 22 pages, 8 figures, accepted to Ap

Thermodynamic properties of extremely diluted symmetric Q-Ising neural networks

Using the replica-symmetric mean-field theory approach the thermodynamic and retrieval properties of extremely diluted {\it symmetric} $Q$-Ising neural networks are studied. In particular, capacity-gain parameter and capacity-temperature phase diagrams are derived for $Q=3, 4$ and $Q=\infty$. The zero-temperature results are compared with those obtained from a study of the dynamics of the model. Furthermore, the de Almeida-Thouless line is determined. Where appropriate, the difference with other $Q$-Ising architectures is outlined.Comment: 16 pages Latex including 6 eps-figures. Corrections, also in most of the figures have been mad

Aplicação da espectroscopia fotoacústica na identificação de componentes do solo.

bitstream/item/77092/1/CT114-2010.pd

Hysteretic Optimization For Spin Glasses

The recently proposed Hysteretic Optimization (HO) procedure is applied to the 1D Ising spin chain with long range interactions. To study its effectiveness, the quality of ground state energies found as a function of the distance dependence exponent, $\sigma$, is assessed. It is found that the transition from an infinite-range to a long-range interaction at $\sigma=0.5$ is accompanied by a sharp decrease in the performance . The transition is signaled by a change in the scaling behavior of the average avalanche size observed during the hysteresis process. This indicates that HO requires the system to be infinite-range, with a high degree of interconnectivity between variables leading to large avalanches, in order to function properly. An analysis of the way auto-correlations evolve during the optimization procedure confirm that the search of phase space is less efficient, with the system becoming effectively stuck in suboptimal configurations much earlier. These observations explain the poor performance that HO obtained for the Edwards-Anderson spin glass on finite-dimensional lattices, and suggest that its usefulness might be limited in many combinatorial optimization problems.Comment: 6 pages, 9 figures. To appear in JSTAT. Author website: http://www.bgoncalves.co

Territorios colaborativos: nuevos desafíos en la educación universitaria

El presente artículo describe algunas contribuciones de un curso que introduce a los participantes a métodos interdisciplinarios para proyectar ciudad con las comunidades locales, anticipando el cambio de paradigma sobre cómo los arquitectos abordarán el espacio público en el mundo atravesado por profundos cambios en las áreas económicas, sociales, culturales y tecnológicas. El papel de los arquitectos es cada vez más variado: parte creadora, parte constructora, parte investigadora, parte facilitadora, y parte gestor del proceso. El currículo del curso ofrece a los participantes la oportunidad de contribuir activamente para moldear de forma más inclusiva e innovadora los desafíos que el espacio público a través de la reducción de la brecha entre ciudadanos, municipios, especialistas (arquitectos, planificadores, sociólogos, ingenieros y gestores) y tecnologías. El objetivo principal ha sido explorar el diálogo social para atender a las nuevas exigencias sociales del proyecto inclusivo y construcción del espacio público urbano en barrios de vivienda social con base en la introducción de tecnologías digitales avanzadas de mapeo, diseño y construcción. Para que los participantes adquieran nuevas competencias de forma eficiente, el programa del curso fue diseñado para promover un conocimiento aplicado a través de la creación de soluciones urbanas, arquitectónicas y sociales de proximidad, con base en lógicas que involucran a los habitantes en el proceso de mapeo, diagnóstico, la decisión, el diseño, la construcción y el espíritu empresarial.info:eu-repo/semantics/acceptedVersio

Questionário de diagnóstico compartilhado da atenção básica: equipes de Saúde da Família típicas x ampliadas

A adscrição de clientela, a relação entre a equipe de atenção básica com as especialidades, as atividades de promoção à saúde e condições de infraestrutura são fatores organizacionais necessários para a Estratégia de Saúde da Família contribuir para proporcionar o cuidado integral no Sistema Único de Saúde (SUS). O objetivo deste artigo é comparar os resultados da aplicação do Questionário de Diagnóstico Compartilhado da Atenção Básica (QDCAB), no tocante aos quesitos referentes à integralidade, entre equipes de Saúde da Família típicas e ampliadas em um município paulista. O método e o QDCAB foram aplicados a equipes de Saúde da Família típicas e àquelas com especialistas das grandes áreas (equipes ampliadas), e a análise foi realizada utilizando o teste de Wilcoxon-Mann-Whitney, permitindo a comparação da distribuição das respostas entre os dois modelos de equipe. As equipes ampliadas estabelecem vínculo de forma mais coletiva (0,0026), porém, não houve diferença nos resultados dos esforços realizados nesse sentido entre os dois modelos de equipe (0,7227). As notas baixas atribuídas às questões relativas à relação da equipe com os especialistas, de uma forma geral, revelam as dificuldades para garantir a integralidade da atenção. As atividades de promoção à saúde receberam notas altas de ambos os modelos. A adequação da estrutura física do centro de saúde recebeu menores notas das equipes típicas (< 0,0001). A relação das equipes com os especialistas é um obstáculo para a garantia da integralidade e, para as equipes típicas, o excesso de demanda e as condições de infraestrutura também representam dificuldades