765 resultados para wireless universal serial-bus dongle


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Wootters [Phys. Rev. Lett. 80, 2245 (1998)] has given an explicit formula for the entanglement of formation of two qubits in terms of what he calls the concurrence of the joint density operator. Wootters's concurrence is defined with the help of the superoperator that flips the spin of a qubit. We generalize the spin-flip superoperator to a universal inverter, which acts on quantum systems of arbitrary dimension, and we introduce the corresponding generalized concurrence for joint pure states of D-1 X D-2 bipartite quantum systems. We call this generalized concurrence the I concurrence to emphasize its relation to the universal inverter. The universal inverter, which is a positive, but not completely positive superoperator, is closely related to the completely positive universal-NOT superoperator, the quantum analogue of a classical NOT gate. We present a physical realization of the universal-NOT Superoperator.

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It has long been recognized that loss and its associated grief are important elements of many adverse life events that affect the entire global population: death, disability, traumatic events, abuse., terminal and chronic illness, aging, addiction, unemployment, relationship breakdown, war, migration, and educational failure. While there is significant empirical evidence of the potential deleterious effects of specific situations of loss across the global community, systematic discussion concerning the common elements of loss that are associated with adverse life situations in general has been limited. This review of the theoretical and empirical literature concerning various losses and the recommendations for care of those affected by such losses identifies common aspects of situations of loss and common recommendations in the care of those confronted by such losses. These common themes of loss are described by simple summary statements that can be communicated to a broad audience, hence enhancing community education and, potentially, community-wide mental health promotion.

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The suitable use of an array antenna at the base station of a wireless communications system can result in improvement in the signal-to-interference ratio (SIR). In general, the SIR is a function of the direction of arrival of the desired signal and depends on the configuration of the array, the number of elements, and their spacing. In this paper, we consider a uniform linear array antenna and study the effect of varying the number of its elements and inter-element spacing on the SIR performance. (C) 2002 Wiley Periodicals, Inc.

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What interactions are sufficient to simulate arbitrary quantum dynamics in a composite quantum system? We provide an efficient algorithm to simulate any desired two-body Hamiltonian evolution using any fixed two-body entangling n-qubit Hamiltonian and local unitary operations. It follows that universal quantum computation can be performed using any entangling interaction and local unitary operations.

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What interactions are sufficient to simulate arbitrary quantum dynamics in a composite quantum system? Dodd [Phys. Rev. A 65, 040301(R) (2002)] provided a partial solution to this problem in the form of an efficient algorithm to simulate any desired two-body Hamiltonian evolution using any fixed two-body entangling N-qubit Hamiltonian, and local unitaries. We extend this result to the case where the component systems are qudits, that is, have D dimensions. As a consequence we explain how universal quantum computation can be performed with any fixed two-body entangling N-qudit Hamiltonian, and local unitaries.

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Wireless medical systems are comprised of four stages, namely the medical device, the data transport, the data collection and the data evaluation stages. Whereas the performance of the first stage is highly regulated, the others are not. This paper concentrates on the data transport stage and argues that it is necessary to establish standardized tests to be used by medical device manufacturers to provide comparable results concerning the communication performance of the wireless networks used to transport medical data. Besides, it suggests test parameters and procedures to be used to produce comparable communication performance results.

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This paper proposes a wireless EEG acquisition platform based on Open Multimedia Architecture Platform (OMAP) embedded system. A high-impedance active dry electrode was tested for improving the scalp- electrode interface. It was used the sigma-delta ADS1298 analog-to-digital converter, and developed a “kernelspace” character driver to manage the communications between the converter unit and the OMAP’s ARM core. The acquired EEG signal data is processed by a “userspace” application, which accesses the driver’s memory, saves the data to a SD-card and transmits them through a wireless TCP/IP-socket to a PC. The electrodes were tested through the alpha wave replacement phenomenon. The experimental results presented the expected alpha rhythm (8-13 Hz) reactiveness to the eyes opening task. The driver spends about 725 μs to acquire and store the data samples. The application takes about 244 μs to get the data from the driver and 1.4 ms to save it in the SD-card. A WiFi throughput of 12.8Mbps was measured which results in a transmission time of 5 ms for 512 kb of data. The embedded system consumes about 200 mAh when wireless off and 400 mAh when it is on. The system exhibits a reliable performance to record EEG signals and transmit them wirelessly. Besides the microcontroller-based architectures, the proposed platform demonstrates that powerful ARM processors running embedded operating systems can be programmed with real-time constrains at the kernel level in order to control hardware, while maintaining their parallel processing abilities in high level software applications.

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Mais do que uma dissertação sobre o envelhecimento da população e o impacto que ela tem na sociedade, a presente tese visa documentar todo o processo projetual desenvolvido para a criação de uma banca de cozinha. Para tal foram tidas em conta, não apenas o tipo de tarefas desenvolvidas nesta zona da habitação como também os índices de fragilidade e de debilidade que os utilizadores mais envelhecidos apresentam. O facto da população envelhecida estar cada vez mais a aumentar, atingindo em alguns países valores preocupantes, associados ao facto de esses mesmos idosos atingirem cada vez mais idades mais avançadas, faz com que haja um aumento do número de pessoas incapacitadas. Assim sendo, o principal objectivo será o desenvolvimento de um projeto assente nas premissas defendidas pelo design universal. Tal projeto tentará encontrar as respostas que melhor respondam às necessidades e problemáticas, não apenas dos utilizadores mais idosos, mas do resto da população, independentemente da sua idade, estatura e condição física.

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In the category of Hom-Leibniz algebras we introduce the notion of Hom-corepresentation as adequate coefficients to construct the chain complex from which we compute the Leibniz homology of Hom-Leibniz algebras. We study universal central extensions of Hom-Leibniz algebras and generalize some classical results, nevertheless it is necessary to introduce new notions of α-central extension, universal α-central extension and α-perfect Hom-Leibniz algebra due to the fact that the composition of two central extensions of Hom-Leibniz algebras is not central. We also provide the recognition criteria for these kind of universal central extensions. We prove that an α-perfect Hom-Lie algebra admits a universal α-central extension in the categories of Hom-Lie and Hom-Leibniz algebras and we obtain the relationships between both of them. In case α = Id we recover the corresponding results on universal central extensions of Leibniz algebras.

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Revista Lusófona de Educação

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The study of public administration has been characterized as a strong international focus, as both governments and scholars have sought to learn from the experience of other societies. While in a perfect world, one would expect a sort of pragmatic universalism, instead, many scholars tend to bring lessons from one country, or from a single cultural reality. This modest contribution lies in showing a series of national experiences rarely brought to the discourse about public administration in Brazil: Canada, Australia, India and the Philippines. Special emphasis will be given to the following: the origins and the development of public administration; the influence of ideology; and the complex tension between global theory and local practices.