10,790 research outputs found

    Guia politicamente incorreto da história do Brasil.

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    Os problemas envolvidos na classificação e na padronização da vida social têm sido alvo de minhas preocupações de estudo há quase uma década. De fato, venho escrevendo um livro sobre esse assunto. Nele, a classificação e a padronização são discutidas dentro de contextos interativos que ressaltam suas características de automatismo, de hábito, de reprodução de valores e de comportamento. Classificar é seguir uma regra adrede preparada no intuito de oferecer coerência a um corpo de ideias, buscando fortalecê‑lo. Para se ter um breve exemplo da importância e das implicações da classificação na vida social, basta lembrar alguns acontecimentos dos séculos 17 e 18 com relação aos estudos dos naturalistas. Sabe-se que, naquele período, a dominação europeia sobre a América carecia de uma teoria científica (classificatória) que desse fundamentos lógicos e empíricos à supremacia europeia pela inevitável ?demonstração? da inferioridade do Novo Mundo. Toda a diversa paisagem natural da América foi alvo desse veículo classificatório: seu ar, seu clima, seus pântanos, seus habitantes, seus animais, sua vegetação, suas terras, suas montanhas, seus vulcões.Obra resenhada: NARLOCH, Leandro. Guia politicamente incorreto da história do Brasil. São Paulo: Leya, 2009. 319 p

    Full-duplex MIMO and PLNC for the Y-network

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    This paper considers a multi-way wireless network with three terminals which want to exchange or share data with the help of a relay: each terminal has some information that wants to transmit to the other two. The traditional way of doing this exchange either involves time-domain multiplexing (TDMA) or dedicated frequency-domain disjoint channels, at the expense of high bandwidth inefficiency. With the advent of network coding, and later physical-layer network coding, it became possible to reduce the number of time slots required to exchange the information between all the terminals. Moreover, using multiple-input multiple-output (MIMO) terminals and relays, the time-usage efficiency can be further boosted by transferring the burden from the time-domain to the spatial-domain via spatial multiplexing. This paper proposes the concatenation of the aforementioned techniques along with loopback interference cancellation, which recently became a central topic for the next generation of the physical-layer of wireless communications. The paper shows a protocol and techniques that allow all the information exchange between terminals to be reduced from the 6 time-slots, required in traditional TDMA, to one time-slot only, provided that the information packets are not too short. The error performance of this system is shown by means of simulation using MIMO Rayleigh fading channels.info:eu-repo/semantics/acceptedVersio

    Alternate islands of multiple isochronous chains in wave-particle interactions

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    We analyze the dynamics of a relativistic particle moving in a uniform magnetic field and perturbed by a standing electrostatic wave. We show that a pulsed wave produces an infinite number of perturbative terms with the same winding number, which may generate islands in the same region of phase space. As a consequence, the number of isochronous island chains varies as a function of the wave parameters. We observe that in all the resonances, the number of chains is related to the amplitude of the various resonant terms. We determine analytically the position of the periodic points and the number of island chains as a function of the wave number and wave period. Such information is very important when one is concerned with regular particle acceleration, since it is necessary to adjust the initial conditions of the particle to obtain the maximum acceleration.Comment: Submitte

    Spin configurations in hard-soft coupled bilayer systems: from rigid magnet to exchange spring transitions

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    We investigate equilibrium properties of an exchange-spring magnetic system constituted of a soft layer (e.g. Fe) of a given thickness on top of a hard magnetic layer (e.g. FePt). The magnetization profile M(z) as a function of the atomic position ranging from the bottom of the hard layer to the top of the soft layer is obtained in two cases with regard to the hard layer: i) in the case of a rigid interface (the FePt layer is a single layer), the profile is obtained analytically as the exact solution of a sine-Gordon equation with Cauchy's boundary conditions. Additional numerical simulations also confirm this result. Asymptotic expressions of M(z) show a linear behavior near the bottom and the top of the soft layer. In addition, a critical value of the number of atomic planes in the soft layer, that is necessary for the onset of spin deviations, is obtained in terms of the anisotropy and exchange coupling between the adjacent plane in the soft layer. ii) in the case of a relaxed interface (the FePt layer is a multilayer), the magnetization profile is obtained numerically for various Fe and FePt films thicknesses and applied field.Comment: 10 pages, 9 figures, PRB submitted (12-07-2010

    Prosodic exercises for children with ASD via virtual therapy

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    which means that there is a wide degree of variation in the way it affects people. It is known that, even though it has a huge spectrum, the characterization of the speech of autistic children has been consensual in the literature as devoid of wealth prosodic parameters manifested by healthy children, such as the emotional aspects that are reflected in communicative interaction. The use of technology as a teaching tool has been growing and the presentation of educational exercises through electronic devices reveals itself as more attractive and captivating for children when compared with traditional methods. In this project, we developed prosodic exercises for intonation assessment in an imitation task, where the main focus is the development and enrichment of prosodic abilities of children with autism spectrum disorders, as a complement to therapy sessions.We evaluated the intonation assessment method, achieving accuracy values between 70%and 83.3%, depending on the feature set adapted (pitch, energy, Mel-Frequency Cepstral features, and pseudo-syllable information), and also by making a fusion of all features. Although the original intention was to integrate these exercises in an existing platform for children diagnosed with ASD, the current implementation is a stand-alone mobile application.info:eu-repo/semantics/publishedVersio

    Biodegradation kinetics of winery wastewater from Port Wine production

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    Winery wastewaters are characterised by seasonality and variable volume and organic load. This fact together with their high content of biodegradable compounds often results in problems in the operation of biological systems as they may lead to poor sludge settleability, floc disintegration and increased presence of solids in the treated effluent. Biodegradation of winery wastewater from a Port Wine production industry was studied in aerobic batch assays, varying substrate and biomass concentrations. More than 90 % of COD was removed in all cases, in a short period when biomass concentration was higher than 3 g VSS L–1. Data was correlated to several kinetic models, and Haldane model best fitted the experimental data, particularly for lower biomass concentrations. Therefore, an initial high biomass concentration should be present in aerobic treatment of winery wastewater, in order to cope with the large fluctuations in their organic loads. These batch assays are valuable for winery wastewater treatment, as they may simulate typical start-ups after short and long shutdown periods often observed in the winery industry.publishe
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