2,323 research outputs found

    Physical properties of a generalized model of multilayer adsorption of dimers

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    This article investigates the physical and statistical properties of two-dimensional structures obtained with a dimer packing model, which may be of great interest in other scientific and technological areas besides theoretical physics. The study is based on extensive computer simulations in order to examine the effect of the orientational anisotropy of dimers deposited following a ballistic deposition process, leading to multilayer networks of complex morphologies dominated by branched fractal architectures. The geometric characteristics of the bulk and contours of these systems, and the transport properties, particularly the electrical conductivity were investigated by varying the orientational anisotropy of the dimers. The results provide information about the fundamental mechanisms underlying formation and behavior of such types of amorphous and disordered matter that are of paramount importance both to physics as well as to environmental and material sciences

    Hybrid confinement of optical and mechanical modes in a bullseye optomechanical resonator

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    Optomechanical cavities have proven to be an exceptional tool to explore fundamental and technological aspects of the interaction between mechanical and optical waves. Such interactions strongly benefit from cavities with large optomechanical coupling, high mechanical and optical quality factors, and mechanical frequencies larger than the optical mode linewidth, the so called resolved sideband limit. Here we demonstrate a novel optomechanical cavity based on a disk with a radial mechanical bandgap. This design confines light and mechanical waves through distinct physical mechanisms which allows for independent control of the mechanical and optical properties. Our device design is not limited by unique material properties and could be easily adapted to allow large optomechanical coupling and high mechanical quality factors with other promising materials. Finally, our demonstration is based on devices fabricated on a commercial silicon photonics facility, demonstrating that our approach can be easily scalable.Comment: 16 pages, 11 figure

    Neinei -- The Neutron Imaging Center at the Brazilian Multipurpose Reactor

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    Neutron imaging is a non-destructive technique for analyzing a wide class of materials, such as archaeological or structures of industrial materials. Technological advances, in recent decades, have had a great impact on the neutron imaging technique, evolving from simple radiographs using films (2D) to modern tomography systems with digital processing (3D). The Instituto de Pesquisas Energ\'eticas e Nucleares (IPEN), in Brazil, houses a 5MW research nuclear reactor, called IEA-R1, where there is a neutron imaging instrument located at the beam hole 08 (BH08) with 1.0×1061.0 \times 10^{6} n/cm2sn/cm^{2}s in the sample position. IEA-R1 is over 60 years old and the future of neutron science in Brazil, including imaging, will be expanded on a new facility called the Brazilian Multipurpose Reactor (RMB). The RMB will house a suite of instruments at the Neutron National Laboratory, including the neutron imaging facility called Neinei. Inspired by recent work, we have calculated the thermal neutron flux at the sample position, using the Monte Carlo method, in the Neinei and compared it to the results obtained with the Neutra (PSI), Antares (FRM II), BT2 (NIST) and DINGO (OPAL) instruments. The results are promising and provide avenues for future improvements.Comment: 8 pages, 9 figures. Preprin

    Relation between TNF-alpha and exercise induced bronchoconstriction

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    Introduction: Exercise-induced bronchoconstriction (EIB) describes an acute airway narrowing that occurs as a result of exercise. EIB is associated with a hyperosmolar environment that lead to airway smooth muscle contraction. The proinflammatory cytokine, TNF-alpha, has a prominent role in the development of airway hiperresponsiveness (AHR). A single bout of heavy exercise can trigger EIB. The aim of this research was to compare the response of TNF-alpha over time with the presence or absence of EIB in marathon runners. Methods: Thirty-eight male runners, who did not have any chronic or acute airway disease, performed maximal cardiopulmonary exercise testing on a treadmill coupled to the gas analyzer (FitMate ™, Cosmed, Italy). Was used a ramp protocol with fixed slope of 1% and an increase of load (1km/h) every minute. Spirometry was performed before (pre), immediately after, five, ten, fifteen and twenty minutes after exercise stress testing. Were considered positive for BIE those athletes that presented a decrease in expiratory volume in one second greater than 10% in any of the spirometric tests. Blood samples were obtained the day before the marathon, immediately and after 72 hours after the race. Cytokines were determined in serum by ELISA. Was used analysis of variance (ANOVA) with two factors, group and time of blood collection, considering repeated measures on the time factor. In the case of statistical significance for interaction group and blood was concluded that the behavior over time was significantly different between EIB negative (-) and EIB positive (+), in this case applied the method of Tukey\u27s multiple comparisons to determine the moment that occurred these differences (p\u3c0.05). Results: We observed a statistically significant difference (p=0.048) in the behavior of the concentration of TNF-alpha between groups EIB- and EIB+. The measure pre of the EIB+ have an higher concentration of TNF-alpha compared to those obtained immediately after the marathon for EIB+ and the results obtained at the three moments for EIB-. (Figure 1). Conclusion: Our results suggests that an inflammatory status in serum of the marathon runners presenting BIE, before the race may be associated with bronchoconstriction triggering

    Transferring knowledge as heuristics in reinforcement learning: A case-based approach

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    The goal of this paper is to propose and analyse a transfer learning meta-algorithm that allows the implementation of distinct methods using heuristics to accelerate a Reinforcement Learning procedure in one domain (the target) that are obtained from another (simpler) domain (the source domain). This meta-algorithm works in three stages: first, it uses a Reinforcement Learning step to learn a task on the source domain, storing the knowledge thus obtained in a case base; second, it does an unsupervised mapping of the source-domain actions to the target-domain actions; and, third, the case base obtained in the first stage is used as heuristics to speed up the learning process in the target domain. A set of empirical evaluations were conducted in two target domains: the 3D mountain car (using a learned case base from a 2D simulation) and stability learning for a humanoid robot in the Robocup 3D Soccer Simulator (that uses knowledge learned from the Acrobot domain). The results attest that our transfer learning algorithm outperforms recent heuristically-accelerated reinforcement learning and transfer learning algorithms. © 2015 Elsevier B.V.Luiz Celiberto Jr. and Reinaldo Bianchi acknowledge the support of FAPESP (grants 2012/14010-5 and 2011/19280-8). Paulo E. Santos acknowledges support from FAPESP (grant 2012/04089-3) and CNPq (grant PQ2 -303331/2011-9).Peer Reviewe

    Efeitos da poluição do ar nas doenças cardiovasculares: estruturas de defasagem

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    OBJETIVO: Investigar a estrutura de defasagem entre exposição à poluição do ar e internações hospitalares por doenças cardiovasculares em idosos, separada por gênero. MÉTODOS: Os dados de saúde de pessoas com mais de 64 anos de idade foram estratificados por gênero, na cidade de São Paulo, entre 1996 e 2001. Os níveis diários de poluentes do ar (CO, PM10, O3, NO2, SO2) e os dados de temperatura mínima e umidade relativa do ar foram também foram analisados. Foram utilizados modelos restritos de distribuição polinomial em modelos aditivos generalizados de regressão de Poisson para estimar os efeitos dos poluentes no dia da exposição e até 20 dias após, controlando-se para sazonalidades de longa e curta durações, feriados e fatores meteorológicos. RESULTADOS: Variações interquartis de PM10 (26,21 mig/m³) e SO2 (10,73 mig/m³) foram associados com aumentos de 3,17% (IC 95%: 2,09-4,25) nas admissões por insuficiência cardíaca congestiva e de 0,89% (IC 95%: 0,18-1,61) para admissões por todas as doenças cardiovasculares no dia da exposição, respectivamente. Os efeitos foram predominantemente agudos e maiores para o gênero feminino. Além disso, foi observado efeito colheita. CONCLUSÕES: Os achados mostraram que as doenças cardiovasculares em São Paulo são fortemente afetadas pela poluição do ar.OBJECTIVE: To assess the lag structure between air pollution exposure and elderly cardiovascular diseases hospital admissions, by gender. METHODS: Health data of people aged 64 years or older was stratified by gender in São Paulo city, Southeastern Brazil, from 1996 to 2001. Daily levels of air pollutants (CO, PM10, O3, NO2, and SO2) , minimum temperature, and relative humidity were also analyzed. It were fitted generalized additive Poisson regressions and used constrained distributed lag models adjusted for long time trend, weekdays, weather and holidays to assess the lagged effects of air pollutants on hospital admissions up to 20 days after exposure. RESULTS: Interquartile range increases in PM10 (26.21 mug/m³) and SO2 (10.73 mug/m³) were associated with 3.17% (95% CI: 2.09-4.25) increase in congestive heart failure and 0.89% (95% CI: 0.18-1.61) increase in total cardiovascular diseases at lag 0, respectively. Effects were higher among female group for most of the analyzed outcomes. Effects of air pollutants for different outcomes and gender groups were predominately acute and some "harvesting" were found. CONLUSIONS: The results show that cardiovascular diseases in São Paulo are strongly affected by air pollution

    GEOMETRIC ANALYSIS BY CONSTRUCTAL DESIGN OF STIFFENED STEEL PLATES UNDER BENDING WITH TRANSVERSE I-SHAPED OR T-SHAPED STIFFENERS

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    Several stiffened plates arrangements subjected to bending were configured applying the Constructal Design Method (CDM) and solved by Finite Element Method (FEM), aiming through the Exhaustive Search (ES) technique analyze the influence of transverse I-Shaped or T-Shaped stiffeners in mechanical behavior. Considering a non-stiffened plate as reference and maintaining the total steel volume constant, a portion of the reference plate was deducted from its thickness, and transformed into stiffeners through the ???? volume fraction parameter, which represents the ratio between the steel volume of the stiffeners and the steel volume of the reference plate. Assuming ???? = 0.3, 25 plates with just I-Shaped stiffeners in longitudinal and transverse directions and 25 plates with I-Shaped stiffeners in longitudinal direction and T-Shaped stiffeners in transverse direction were proposed. The results showed that the plates with transverse T-Shaped stiffeners are more effective, reducing the maximum von Mises stress and maximum deflection, respectively, in up to more than 60% and 50% when compared with the plates with just I-Shaped stiffeners

    A combined approach for comparative exoproteome analysis of Corynebacterium pseudotuberculosis

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    Background: Bacterial exported proteins represent key components of the host-pathogen interplay. Hence, we sought to implement a combined approach for characterizing the entire exoproteome of the pathogenic bacterium Corynebacterium pseudotuberculosis, the etiological agent of caseous lymphadenitis (CLA) in sheep and goats. Results: An optimized protocol of three-phase partitioning (TPP) was used to obtain the C. pseudotuberculosis exoproteins, and a newly introduced method of data-independent MS acquisition (LC-MSE) was employed for protein identification and label-free quantification. Additionally, the recently developed tool SurfG+ was used for in silico prediction of sub-cellular localization of the identified proteins. In total, 93 different extracellular proteins of C. pseudotuberculosis were identified with high confidence by this strategy; 44 proteins were commonly identified in two different strains, isolated from distinct hosts, then composing a core C. pseudotuberculosis exoproteome. Analysis with the SurfG+ tool showed that more than 75% (70/93) of the identified proteins could be predicted as containing signals for active exportation. Moreover, evidence could be found for probable non-classical export of most of the remaining proteins. Conclusions: Comparative analyses of the exoproteomes of two C. pseudotuberculosis strains, in addition to comparison with other experimentally determined corynebacterial exoproteomes, were helpful to gain novel insights into the contribution of the exported proteins in the virulence of this bacterium. The results presented here compose the most comprehensive coverage of the exoproteome of a corynebacterial species so far
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