1,442 research outputs found

    Witnessed Entanglement

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    We present a new measure of entanglement for mixed states. It can be approximately computable for every state and can be used to quantify all different types of multipartite entanglement. We show that it satisfies the usual properties of a good entanglement quantifier and derive relations between it and other entanglement measures.Comment: Revised version. 7 pages and one figur

    Separable Multipartite Mixed States - Operational Asymptotically Necessary and Sufficient Conditions

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    We introduce an operational procedure to determine, with arbitrary probability and accuracy, optimal entanglement witness for every multipartite entangled state. This method provides an operational criterion for separability which is asymptotically necessary and sufficient. Our results are also generalized to detect all different types of multipartite entanglement.Comment: 4 pages, 2 figures, submitted to Physical Review Letters. Revised version with new calculation

    A Robust Semidefinite Programming Approach to the Separability Problem

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    We express the optimization of entanglement witnesses for arbitrary bipartite states in terms of a class of convex optimization problems known as Robust Semidefinite Programs (RSDP). We propose, using well known properties of RSDP, several new sufficient tests for the separability of mixed states. Our results are then generalized to multipartite density operators.Comment: Revised version (minor spell corrections) . 6 pages; submitted to Physical Review

    Schmidt balls around the identity

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    Robustness measures as introduced by Vidal and Tarrach [PRA, 59, 141-155] quantify the extent to which entangled states remain entangled under mixing. Analogously, we introduce here the Schmidt robustness and the random Schmidt robustness. The latter notion is closely related to the construction of Schmidt balls around the identity. We analyse the situation for pure states and provide non-trivial upper and lower bounds. Upper bounds to the random Schmidt-2 robustness allow us to construct a particularly simple distillability criterion. We present two conjectures, the first one is related to the radius of inner balls around the identity in the convex set of Schmidt number n-states. We also conjecture a class of optimal Schmidt witnesses for pure states.Comment: 7 pages, 1 figur

    Effects of Isometric Handgrip Training in Patients With Peripheral Artery Disease: A Randomized Controlled Trial

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    BackgroundMeta‐analyses have shown that isometric handgrip training (IHT) can reduce brachial systolic and diastolic blood pressure (BP) by >6/4 mm Hg, respectively. However, whether IHT promotes these effects among patients with peripheral artery disease, who exhibit severe impairment in cardiovascular function, is currently unknown. This study aimed to evaluate the effects of IHT on the cardiovascular function of patients with peripheral artery disease. Methods and ResultsA randomized controlled trial with peripheral artery disease patients assigned to either the IHT or control group was conducted. The IHT group performed 3 sessions per week, for 8 weeks, of unilateral handgrip exercises, consisting of 4 sets of isometric contractions for 2 minutes at 30% of maximum voluntary contraction and a 4‐minute interval between sets. The control group received a compression ball in order to minimize the placebo effects, representing sham training. The primary outcome was brachial BP. The secondary outcomes were central BP, arterial stiffness parameters, cardiac autonomic modulation, and vascular function. The IHT program reduced diastolic BP (75 [10] mm Hg preintervention versus 72 [11] mm Hg postintervention), with no change in the control group (74 [11] mm Hg preintervention versus 74 [11] mm Hg postintervention), with this between‐group difference being significant (P=0.04). Flow‐mediated dilation improved in the IHT group (6.0% [5.7] preintervention versus 9.7% [5.5] postintervention), with no change in the control group (7.6% [5.5] preintervention versus 7.4% [5.1] postintervention), with this between‐group difference being significant (P=0.04). There was no change in other measured variables over the intervention period. ConclusionsIHT reduced brachial diastolic BP and improved local vascular function in patients with peripheral artery disease

    VILA DE PICINGUABA : O CASO DE UMA COMUNIDADE CAlÇARA NO INTERIOR DE UMA ÁREA PROTEGIDA

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    A Vila de Picinguaba no município de Ubatuba, Estado de São Paulo, está desde 1979 situada no interior do Parque Estadual da Serra do Mar, no denominado Núcleo Picinguaba. Este Núcleo tem aproximadamente 8.000 ha e é a única região do parque que chega até o mar. Originalmente, a vila era de pescadores artesanais, que detêm características culturais específicas. Nos últimos 15 anos, houve um processo de crescimento e transformação desta vila, o que vem descaracterizando a cultura local, ameaçando os objetivos de implantação do parque e degenerando a qualidade de vida de seus habitantes. Como retrato desta situação, temos hoje que 51,9% das edificações domiciliares são de propriedade de turistas. Para que houvesse 'tJma discussão conjunta, entre a população habitante da vila e o Instituto Florestal, das propostas de manejo para a área foram realizados dois diagnósticos (ambiental e de ocupação) e o seminário: "Vila de Picinguaba: Propostas para seu desenvolvimento e preservação" O trabalho aqui apresentado visa apontar as possibilidades de manejo desta área, considerando as finalidades conservacionistas de um parque estadual e a importância de se possibilitar a expressão de aspectos culturais tradicionais, ainda existentes no Estado de São Paulo
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