Serviço de vídeo a pedido através da Internet

O presente téxto tem o objectivo de introduzir os conceitos relacionados com a transmissão de vídeo através da Internet. Através da realização, implementação e estudo de uma plataforma de suporte ao serviço de vídeo a pedido, analisam-se os principais problemas inerentes à concepção de um serviço deste tipo. Apresenta-se uma solução para um clube de vídeo on-line, mostrando uma implementação possível para o serviço de vídeo em tempo real. Por fim fazem-se as conclusões e enumeram-se algumas direcções para melhorar a qualidade do serviço

A Killing Disease Epidemic Among Displaced Sudanese Population Identified as Visceral Leishmaniasis.

A fatal disease epidemic affected the Bentiu area in southern Sudan and led to a mass migration of the Nuer tribe searching for treatment. The initially available information revealed a high mortality rate due to a possible occurrence of tuberculosis, malaria, enteric fever or visceral leishmaniasis (VL). Serological screening of 53 of the most severely affected patients in an enzyme-linked immunosorbent assay (ELISA) or an improved direct agglutination test (DAT) revealed positivity for VL. In 39 of those patients, diagnosis was confirmed by identification of Leishmania donovani amastigotes in lymph node or bone-marrow aspirates. In a total of 2714 patients observed, 1195 (44.0%) had clinical symptoms suggesting VL: DAT positive titers (1:3200-greater than or equal to 1:12800) were obtained in 654 (24.1%), of whom 325 were confirmed parasitologically. Forty-two VL cases died before or during treatment, giving a mortality rate of 6.4%. Among the intercurrent infections diagnosed in the VL population (654), respiratory involvements (31.7%) and malaria (10.7%) were most prevalent. With the exception of four (0.6%), all other VL patients (509) responded readily to sodium stibogluconate. The factors initiating the outbreak are discussed. Malnutrition and nomadic movements to potential VL endemic areas appeared to be the most important. HIV infection as a possible predisposition seemed remote considering the clinical and epidemiological similarity to VL occurring in East Africa, adequate humoral response in DAT, and immediate positive response to specific anti-Leishmania chemotherapy

A distributed load scheduling mechanism for micro grids

Several protocols have recently been defined for smart grids that enable the communication between electric devices and energy management systems. While these protocols and architectures can already be applied in different fields of micro grids, it is still not clear how the distributed resources and constraints of such electrical grids can be managed in an optimum way. In order to achieve a reduction in electricity costs and maximizing investments made in renewable sources, an optimization mechanism should be used to perform load scheduling, considering different variables such as forecasted power generation curve from renewable sources, different tariffs' rates, electric circuit constraints, user restrictions and correspondent comfort levels. Given these considerations, this work defines and evaluates a distributed micro grid resource management architecture and protocol which is able to optimize load scheduling while considering all the mentioned restrictions and parameters. The proposed architecture was implemented on a multi-agent simulator and the performed tests show that significant reductions in electricity cost can be achieved using this methodology. © 2014 IEEE

Cavity-aided quantum parameter estimation in a bosonic double-well Josephson junction

We describe an apparatus designed to make non-demolition measurements on a Bose-Einstein condensate (BEC) trapped in a double-well optical cavity. This apparatus contains, as well as the bosonic gas and the trap, an optical cavity. We show how the interaction between the light and the atoms, under appropriate conditions, can allow for a weakly disturbing yet highly precise measurement of the population imbalance between the two wells and its variance. We show that the setting is well suited for the implementation of quantum-limited estimation strategies for the inference of the key parameters defining the evolution of the atomic system and based on measurements performed on the cavity field. This would enable {\it de facto} Hamiltonian diagnosis via a highly controllable quantum probe.Comment: 8 pages, 5 figures, RevTeX4; Accepted for publication in Phys. Rev.

Autonomous temporal pseudo-labeling for fish detection

The first major step in training an object detection model to different classes from the available datasets is the gathering of meaningful and properly annotated data. This recurring task will determine the length of any project, and, more importantly, the quality of the resulting models. This obstacle is amplified when the data available for the new classes are scarce or incompatible, as in the case of fish detection in the open sea. This issue was tackled using a mixed and reversed approach: a network is initiated with a noisy dataset of the same species as our classes (fish), although in different scenarios and conditions (fish from Australian marine fauna), and we gathered the target footage (fish from Portuguese marine fauna; Atlantic Ocean) for the application without annotations. Using the temporal information of the detected objects and augmented techniques during later training, it was possible to generate highly accurate labels from our targeted footage. Furthermore, the data selection method retained the samples of each unique situation, filtering repetitive data, which would bias the training process. The obtained results validate the proposed method of automating the labeling processing, resorting directly to the final application as the source of training data. The presented method achieved a mean average precision of 93.11% on our own data, and 73.61% on unseen data, an increase of 24.65% and 25.53% over the baseline of the noisy dataset, respectively.info:eu-repo/semantics/publishedVersio

Relativistic quantum mechanics with trapped ions

We consider the quantum simulation of relativistic quantum mechanics, as described by the Dirac equation and classical potentials, in trapped-ion systems. We concentrate on three problems of growing complexity. First, we study the bidimensional relativistic scattering of single Dirac particles by a linear potential. Furthermore, we explore the case of a Dirac particle in a magnetic field and its topological properties. Finally, we analyze the problem of two Dirac particles that are coupled by a controllable and confining potential. The latter interaction may be useful to study important phenomena as the confinement and asymptotic freedom of quarks.Comment: 17 pages, 4 figure

Generating coherence and entanglement with a finite-size atomic ensemble in a ring cavity

We propose a model to study the coherence and entanglement resulting from the interaction of a finite-size atomic ensemble with degenerate counter-propagating field modes of a high-Q ring cavity. Our approach applies to an arbitrary number of atoms N and includes the spatial variation of the field throughout the ensemble. We report several new interesting aspects of coherence and entangled behavior that emerge when the size of the atomic ensemble is not taken to the thermodynamic limit of N>>1. Under such conditions, it is found that the counter-propagating cavity modes, although in the thermodynamic limit are mutually incoherent and exhibit no one-photon interference, the modes can, however, be made mutually coherent and exhibit interference after interacting with a finite-size atomic ensemble. It is also found that the spatial redistribution of the atoms over a finite size results in nonorthogonality of the collective bosonic modes. This nonorthogonality leads to the super-bunching effect that the correlations of photons of the individual cavity modes and of different modes are stronger than those of a thermal field. However, we find that the correlations are not strong enough to violate the Cauchy-Schwarz inequality and to produce squeezing and entanglement between the modes. Therefore, we investigate the spectral distributions of the logarithmic negativity and the variances of the output fields. These functions determine squeezing and entanglement properties of the output cavity fields and can be measured by a homodyne technique. We find that the entanglement is redistributed over several components of the spectrum and the finite-size effect is to concentrate the entanglement at the zero-frequency component of the spectrum.Comment: Published versio

Empirical Characterization of Particle Size Distribution Spatial Dynamics for Detection of Helminth Eggs in Waste Stabilization Ponds (WSP)

This study assesses the seasonal particle size distribution (PSD) dynamics inside a WSP (Buguruni, Tanzania) to understand the settling dynamics of wastewater particles with a specific focus on helminth eggs. Results indicate that particles coming into the pond are mainly supracolloidal and settleables, at 52.9% and 45.6%, respectively, in the dry season and 48.9% and 49.9%, respectively, in the wet season. Inflow PSD is a unimodal distribution that splits into settling and suspended PSDs, with an indication of particle breakage as shown by the increased volume of smaller particles, and hence the appearance of a bimodal distribution for the suspended particles. Up to 61.5% and 45.2% of particles that fall within the size range of helminths eggs are suspended during the dry and wet seasons, respectively, and have the potential to be carried in the effluent, causing contamination