1,361 research outputs found

    Mode-independent H2-control of a DC motor modeled as a Markov jump linear system

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    This brief presents a control strategy for Markov jump linear systems (MJLS) with no access to the Markov state (or mode). The controller is assumed to be in the linear state-feedback format and the aim of the control problem is to design a static mode-independent gain that minimizes a bound to the corresponding H2 -cost. This approach has a practical appeal since it is often difficult to measure or to estimate the actual operating mode. The result of the proposed method is compared with that of a previous design, and its usefulness is illustrated by an application that considers the velocity control of a DC motor device subject to abrupt failures that is modeled as an MJLS

    Two-band fast Hartley transform

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    This article has been made available through the Brunel Open Access Publishing Fund.Efficient algorithms have been developed over the past 30 years for computing the forward and inverse discrete Hartley transforms (DHTs). These are similar to the fast Fourier transform (FFT) algorithms for computing the discrete Fourier transform (DFT). Most of these methods seek to minimise the complexity of computations and or the number of operations. A new approach for the computation of the radix-2 fast Hartley transform (FHT) is presented. The proposed algorithm, based on a two-band decomposition of the input data, possesses a very regular structure, avoids the input or out data shuffling, requires slightly less multiplications than the existing approaches, but increases the number of additions

    A systematic review of economic evaluations of the use of memantine alone or combined with donepezil for moderate to severe Alzheimer’s disease

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    Objective: To synthesize the available evidence and state of the art of economic evaluations which evaluate the use of memantine, whether alone or combined with donepezil, for moderate to severe Alzheimer’s disease (AD), focusing on the analytical decision models built. Method: The electronic databases MEDLINE, EMBASE, NHS EED, CEA Registry and LILACS were searched for references. After duplicates were removed, two independent reviewers evaluated the titles and abstracts and subsequently the full texts. The Drummond M. tool was used to evaluate the quality of the studies. Results: After the application of the eligibility criteria, twelve complete economic evaluations were included. One evaluation was a clinical trial, two involved simulations and nine used Markov models. The main outcome measure adopted was dominated by cost per quality adjusted life year (QALY). The use of memantine was considered cost-effective and dominant in eight studies; while in a single study, its use was dominated when compared to donepezil for moderate AD. Sensitivity analyzes were systematically performed, with robust results. The quality assessment indicated that the methodological quality of the studies was good. Conclusion: Although there is some controversy regarding the benefits derived from the use of memantine, whether combined or not with donepezil, the evidence collected suggests that it is cost-effective in the countries where the studies were performed. However, local economic studies need to be performed, given the significant variability derived from the different parameters adopted in the evaluations

    Aedes (Stegomyia) aegypti L. e a culicideofauna associada em área urbana da região sul, Brasil

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    Foram mostrados alguns aspectos sobre a ecologia de 11 espécies de Culicidae que procriam em recipientes, em uma área urbana do Sul do Brasil. Os mais variados tipos de recipientes foram listados como eficientes criadouros para larvas de culicídeos. Aedes aegypti apareceu como espécie recém-introduzida e limitada somente a duas áreas da cidade. As espécies predominantes foram: Culex quinquefasciatus, Culex coronator, Aedes aegypti, Aedes fluviatilis e Limatus durhamii.Some aspects of the ecology of eleven species of Culicidae that were found breeding in recipients in an urban area of Southern Brazil are presented. A great variety of recipients were listed as efficient breeding sites. Apparently Aedes aegypti has been recently introduced into the region and was limited to two areas of the city. Culex quinquefasciatus, Cx. coronator, Ae. aegypti, Ae. fluviatilis e Limatus durhamii were the predominant species

    Scalar perturbation spectra from warm inflation

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    We present a numerical integration of the cosmological scalar perturbation equations in warm inflation. The initial conditions are provided by a discussion of the thermal fluctuations of an inflaton field and thermal radiation using a combination of thermal field theory and thermodynamics. The perturbation equations include the effects of a damping coefficient Γ\Gamma and a thermodynamic potential VV. We give an analytic expression for the spectral index of scalar fluctuations in terms of a new slow-roll parameter constructed from Γ\Gamma. A series of toy models, inspired by spontaneous symmetry breaking and a known form of the damping coefficient, lead to a spectrum with ns>1n_s>1 on large scales and ns<1n_s<1 on small scales.Comment: 12 pages, 5 figures, RevTeX 4, revised with extra figure

    Synergistic warm inflation

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    We consider an alternative warm inflationary scenario in which nn scalar fields coupled to a dissipative matter fluid cooperate to produce power--law inflation. The scalar fields are driven by an exponential potential and the bulk dissipative pressure coefficient is linear in the expansion rate. We find that the entropy of the fluid attains its asymptotic value in a characteristic time proportional to the square of the number of fields. This scenario remains nearly isothermal along the inflationary stage. The perturbations in energy density and entropy are studied in the long--wavelength regime and seen to grow roughly as the square of the scale factor. They are shown to be compatible with COBE measurements of the fluctuations in temperature of the CMB.Comment: 13 pages, Revtex 3 To be published in Physical Review

    New Upper Limit of Terrestrial Equivalence Principle Test for Rotating Extended Bodies

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    Improved terrestrial experiment to test the equivalence principle for rotating extended bodies is presented, and a new upper limit for the violation of the equivalence principle is obtained at the level of 1.610-7% \times 10^{\text{-7}}, which is limited by the friction of the rotating gyroscope. It means the spin-gravity interaction between the extended bodies has not been observed at this level.Comment: 4 page

    Florística e fitossociologia de um trecho de Floresta ombrófila densa de terra firme na área de influência da Usina Hidrelétrica Belo Monte, Pará, Brasil

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    The objective of the present study was to characterise the floristic and phytosociological composition on a stretch of dense “Terra Firme” rainforest located in the Belo Monte hydroelectric plant area of influence, located in the state of Pará, Brazil. All trees with DAP > 10 cm situated in 75 permanent plots of 1 ha were inventoried. 27,126 individuals trees (361 ind.ha-1), distributed in 59 botanical families, comprising 481 species were observed. The families with the largest number of species were Fabaceae (94), Araceae (65) and Arecaceae (43), comprising 43.7% of total species. The species Alexa grandiflora (4.41), Cenostigma tocantinum (2.50) and Bertholletia excelsa (2.28) showed the highest importance values (IV). The ten species with greater IV are concentrated (22%). The forest community has high species richness and can be classified as diverse age trees, heterogeneous and of medium conservation condition. © 2015, Instituto Internacional de Ecologia. All rights reserved

    Non-Minimal Warm Inflation and Perturbations on the Warped DGP Brane with Modified Induced Gravity

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    We construct a warm inflation model with inflaton field non-minimally coupled to induced gravity on a warped DGP brane. We incorporate possible modification of the induced gravity on the brane in the spirit of f(R)f(R)-gravity. We study cosmological perturbations in this setup. In the case of two field inflation such as warm inflation, usually entropy perturbations are generated. While it is expected that in the case of one field inflation these perturbations to be removed, we show that even in the absence of the radiation field, entropy perturbations are generated in our setup due to non-minimal coupling and modification of the induced gravity.Comment: 29 pages, 7 figures, Accepted by Gen. Rel Gravi
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