Entanglement versus mixedness for coupled qubits under a phase damping channel

Quantification of entanglement against mixing is given for a system of coupled qubits under a phase damping channel. A family of pure initial joint states is defined, ranging from pure separable states to maximally entangled state. An ordering of entanglement measures is given for well defined initial state amount of entanglement.Comment: 9 pages, 2 figures. Replaced with final published versio

Handling confidentiality and privacy on cloud-based health information systems

Health-related data include not only the patient’s personal information, but also specific information about the patient health problems, supplementary diagnostic examination results, and much more. All this information is extremely sensitive and should only be accessed by the proper entities and actors, for special specific purposes. Described herein is an approach to address security and privacy of health-related data based on rights management technologies, with an architecture to minimize security risks and privacy conerns. This approach consists of the reutilisation of an open-source and open-specifications rights management system, and designing and adapting the necessary components to address the specific security and privacy requirements that must be faced when managing health and patient data.info:eu-repo/semantics/acceptedVersio

Report on the capability assessment and improvement workshop (CAIW) at iPres 2013

While Digital Preservation is making progress in terms of tool development, progressive establishment of standards and increasing activity in user communities, there is a lack of approaches to systematically assessing, comparing and improving how organizations go about achieving their preservation goals. This currently presents a challenge to many organizations for whom digital stewardship is a concern and reveals a substantial gap between theory and practice. To provide an interactive, focused venue for those interested in systematic approaches for assessment and improvement, we organized the first Capability Assessment and Improvement Workshop (CAIW) in Lisbon, on September 5, 2013, as part of the 10th International Conference on Digital Preservation (iPres 2013). This article provides a report on the issues discussed and attempts to synthesize the main conclusions with the intention of stimulating further discussion in the community on this topic

Late-Time Tails of Wave Propagation in Higher Dimensional Spacetimes

We study the late-time tails appearing in the propagation of massless fields (scalar, electromagnetic and gravitational) in the vicinities of a D-dimensional Schwarzschild black hole. We find that at late times the fields always exhibit a power-law falloff, but the power-law is highly sensitive to the dimensionality of the spacetime. Accordingly, for odd D>3 we find that the field behaves as t^[-(2l+D-2)] at late times, where l is the angular index determining the angular dependence of the field. This behavior is entirely due to D being odd, it does not depend on the presence of a black hole in the spacetime. Indeed this tails is already present in the flat space Green's function. On the other hand, for even D>4 the field decays as t^[-(2l+3D-8)], and this time there is no contribution from the flat background. This power-law is entirely due to the presence of the black hole. The D=4 case is special and exhibits, as is well known, the t^[-(2l+3)] behavior. In the extra dimensional scenario for our Universe, our results are strictly correct if the extra dimensions are infinite, but also give a good description of the late time behaviour of any field if the large extra dimensions are large enough.Comment: 6 pages, 3 figures, RevTeX4. Version to appear in Rapid Communications of Physical Review

Automatic speaker segmentation using multiple features and distance measures: a comparison of three approaches

This paper addresses the problem of unsupervised speaker change detection. Three systems based on the Bayesian Information Criterion (BIC) are tested. The first system investigates the AudioSpectrumCentroid and the AudioWaveformEnvelope features, implements a dynamic thresholding followed by a fusion scheme, and finally applies BIC. The second method is a real-time one that uses a metric-based approach employing the line spectral pairs and the BIC to validate a potential speaker change point. The third method consists of three modules. In the first module, a measure based on second-order statistics is used; in the second module, the Euclidean distance and T2 Hotelling statistic are applied; and in the third module, the BIC is utilized. The experiments are carried out on a dataset created by concatenating speakers from the TIMIT database, that is referred to as the TIMIT data set. A comparison between the performance of the three systems is made based on t-statistics

Transferência de tecnologia: distribuição geográfica de mudas de variedades de banana lançadas pela Embrapa.

Na fruticultura, bem como em qualquer atividade agrícola, um dos insumos essenciais é a escolha do material genético (sementes/mudas) para a implantação do pomar. A muda deve ter identidade genética comprovada e resistência às principais doenças da cultura. Entretanto, muitos agricultores por uma série de fatores (poder econômico, desinformação, resistência, escassez de mudas no mercado, entre outros) acabam utilizando mudas de baixa qualidade genética e fitossanitária. Na cultura da bananeira isto é evidente, na medida em que os agricultores utilizam mudas provenientes de seu próprio bananal e ou de pomares vizinhos, aumentando o risco de ocorrência de doenças no bananal a ser implantado (ALVES et al., 2004)

Extreme vortex pinning in the non-centrosymmetric superconductor CePt3_{3}Si

We report on the vortex dynamics of a single crystal of the non-centrosymmetric heavy-fermion superconductor CePt$_{3}$Si. Decays of the remnant magnetization display a clean logarithmic time dependence with rates that follow the temperature dependence expected from the Kim-Anderson theory. The creep rates are lower than observed in any other centrosymmetric superconductor and are not caused by high critical currents. On the contrary, the critical current in CePt$_{3}$Si is considerably lower than in other superconductors with strong vortex pinning indicating that an alternative impediment on the flux line motion might be at work in this superconductor.Comment: 4 pages, 5 figure

Decoherence induced by a phase-damping reservoir

A phase damping reservoir composed by $N$-bosons coupled to a system of interest through a cross-Kerr interaction is proposed and its effects on quantum superpo sitions are investigated. By means of analytical calculations we show that: i-) the reservoir induces a Gaussian decay of quantum coherences, and ii-) the inher ent incommensurate character of the spectral distribution yields irreversibility . A state-independent decoherence time and a master equation are both derived an alytically. These results, which have been extended for the thermodynamic limit, show that nondissipative decoherence can be suitably contemplated within the EI D approach. Finally, it is shown that the same mechanism yielding decoherence ar e also responsible for inducing dynamical disentanglement.Comment: 8 pages, 3 figure