Finite-size effects on the phase structure of the Nambu-Jona-Lasinio model

The Nambu-Jona-Lasinio (NJL) model is one of the most frequently used four-fermion models in the study of dynamical symmetry breaking. In particular, the NJL model is convenient for that analysis at finite temperature, chemical potential and size effects, as has been explored in the last decade. With this motivation, we investigate the finite-size effects on the phase structure of the NJL model in $D = 3$ Euclidean dimensions, in the situations that one, two and three dimensions are compactified. In this context, we employ the zeta-function and compactification methods to calculate the effective potential and gap equation. The critical lines that separate trivial and non-trivial fermion mass phases in a second order transition are obtained. We also analyze the system at finite temperature, considering the inverse of temperature as the size of one of the compactified dimensions

Multiresolution MBMS transmissions for MIMO UTRA LTE systems

Hierarchical constellations constitute a simple technique for achieving multiresolution and, therefore, are appealing for MBMS (Multimedia Broadcast and Multicast Service). In this paper we consider the use of M-QAM hierarchical constellations (Quadrature Amplitude Modulation) combined with MIMO (Multiple Input Multiple Output) for the transmission of multicast and broadcast services in UTRA (Universal Mobile Telecommunications System Terrestrial Radio Access) Long Term Evolution (LTE) systems based on Orthogonal Frequency Division Multiplexing (OFDM). Due to the demanding channel estimation requirements and the high sensitivity to interference resulting from the usage of several antennas and hierarchical constellations, an enhanced receiver based on the turbo concept is employed and its performance is evaluated.info:eu-repo/semantics/acceptedVersio

Stability of blood gases when refrigerated

Background: Blood gas analysis is a widely used procedure. In clinical practice, the physicians may not always have a blood gas analyzer in their proximity. Not infrequently, blood gas samples are stored in a fridge or on ice and read retrospectively. Continued anaerobic and aerobic metabolism in the blood may alter blood gases in the interval between drawing arterial blood and its analysis, which may cause a fall in the PaO2 and pH and a rise in the PaCO2. Methods: Two sets of arterial blood samples were obtained from hospitalized patients. After the initial analysis, one sample from each patient was put in raw ice within a specimen bag (0 to +1 oC) and the other in the fridge (+4 to +8 oC). These samples were submitted to serial analysis at 30 minutes, 1 hour and 2 hours after the initial analysis. Results: Two hundred arterial blood gas results from 25 patients were analysed. The mean values of PaO2, PaCO2, HCO3-, Na+, K+, Ca2+ and lactate at 0 minutes, 30 minutes, 1 hour and 2 hours were not signifi cantly different between the two alternatives of storage. However, within each group, signifi cant changes were found over time for PaO2, K+, Na+, Ca2+ and lactate. Conclusions: When using plastic syringes, arterial blood gas analysis should be processed shortly after collecting the sample. Despite the fact that low temperatures can slow down the metabolism, neither the ice nor the fridge preserved all the sample parameters

Evaluation of soil-water parameters of a Red Latosol under pasture and 'cerrado'

O objetivo primeiro neste trabalho foi avaliar a qualidade fisico-hídrica do solo em áreas sob pastejo, em relação a um cerrado natural. Os tratamentos foram: cerrado natural, cerrado antropizado (pastejado na estação seca) e três pastagens cultivadas, com diferentes graus de cobertura do solo. O estudo foi realizado na Embrapa Cerrados em um Latossolo Vermelho, nas camadas de 0-5, 10-15, 40-55 e 70-80 cm, cujos parâmetros avaliados foram condutividade hidráulica saturada (Ks), capacidade de água disponível (CAD), densidade do solo (Ds) e macroporosidade (Ma). A qualidade fisico-hídrica do solo nas áreas sob pastejo foi analisada tendo-se como referência os parâmetros medidos no cerrado natural. Observou-se semelhança estatística da CAD na camada 0-5 cm para todas as áreas mas ocorreu drástica redução da saturação efetiva nas áreas sob pastejo, explicada principalmente pela queda na macroporosidade. A redução média da Ma foi de 70,8%, ocasionando um decréscimo da ordem de 73,6% da Ks nos primeiros 15 cm das áreas sob pastejo, podendo-se concluir que a camada superficial do solo foi a mais afetada pelo pastejo, com perda significativa da qualidade fisico-hídrica e previsível redução na capacidade de infiltração da água no solo. _________________________________________________________________________________ ABSTRACTThe objective of this study was to evaluate the soil-water quality under grazing pastures in comparison to a natural 'cerrado' (savanna). The treatments were: natural 'cerrado', grazed 'cerrado' during the dry season, and three cultivated pastures with different degrees of soil covering. The research was conducted at the Embrapa Cerrados, on a Red Latosol in the 0-5, 10-15, 40-55, and 70-80 cm soil layers, in which the following parameters were quantified: saturated hydraulic conductivity (Ks), available water capacity (CAD), soil bulk density (Ds), and macroporosity (Ma). The soil-water quality was determined by taking as references the corresponding parameters measured in the natural 'cerrado'. Statistical similarity of CAD values in the 0-5 cm soil layer for all treatments was observed. However, there was a drastic reduction of the effective saturation in the treatments of grazed areas, mainly explained by the reduction in macroporosity. The mean decrease in Ma was 70.8%, causing a 73.6% decline in Ks in the 15 cm upper soil layer of the grazed areas, which led to the conclusion that the surface soil layers were the most affected by the grazing activity, with significant deterioration of their soil-water quality and a predictable reduction in water-infiltration capacity

Seleção de linhagens de feijoeiro resistentes à antracnose com grãos tipo rosinha ou carioca.

O objetivo deste trabalho foi identificar linhagens com grão tipo rosinha ou carioca, que além de serem resistentes à antracnose, seja altamente produtivas e resistentes à mancha angular

The International Year of Planet Earth in Portugal : past activities and further developments

The Portuguese National Committee for the IYPE was created in the framework of the Portuguese National Commission for UNESCO, in April 2007. The Committee incorporated the contributions of 220 private and public organizations, mainly municipalities and educational institutions of all levels, and sponsored more than 500 activities since then. The Scientific Programme emphasized relevant cooperation between Earth scientists from the Community of Portuguese Speaking Countries, under the guidance of their National Committees (Angola, Brazil, Cape Verde and Mozambique). In consideration of the community of 230 million Portuguese speaking people, the Portuguese National Committee translated and printed the twelve brochures produced by IUGS- UNESCO, posted them on the official website (www.anoplaneta-terra.org), and supported several editions also in Braille, in order to make Earth sciences readily accessible to all citizens. As a result of these accomplishments during the IYPE triennium (2007-2009), the Portuguese National Committee was invited by the UNESCO-IUGS Corporation to co-organize Planet Earth Lisbon ́09, the Global Closure Event of the IYPE, which took place in Lisbon, 20th to 22nd November 2009

Friction and wear performance of HFCVD nanocrystalline diamond coated silicon nitride ceramics

Silicon nitride (Si3N4) ceramics were selected as substrates due to their thermal and chemical compatibility to diamond that ensure the adequate NCD adhesion for mechanical purposes. NCD deposition was performed by hot-filament chemical vapour method (HFCVD) using Ar/H2/CH4 gas mixtures. The tribological assessment of homologous pairs of NCD films was accomplished using reciprocating ball-on-flat tests using NCD coated Si3N4 plates and balls. The friction evolution is characterized by an initial running-in regime with a sharp peak up to 0.70, shortly followed by a steady-state regime identified by very low friction coefficients values (0.02–0.03). The threshold load prior to delamination depends on the starting surface roughness of the substrates and attains a value of ¨40 N. In terms of wear performance, the NCD films reveal a mild wear regime (K~10-7 mm3 N-1 m-1) for self-mated dry sliding conditions