Imaging 3D seismic velocity along the seismogenic zone of Algarve region (southern Portugal)

The present seismic tomographic study is focused around Algarve region, in South of Portugal. To locate the seismic events and find the local velocity structure of epicentral area, the P and S arrival times at 38 stations are used. The data used in this study were obtained during the Algarve campaign which worked from January/2006 to July/2007. The preliminary estimate of origin times and hypocentral coordinates are determined by the Hy- poinverse program. Linearized inversion procedure was applied to comprise the following two steps: 1) finding the minimum 1D velocity model using Velest and 2) simultaneous relocation of hypocenters and determination of local velocity structure. The velocity model we have reached is a 10 layer model which gave the lowest RMS, after several runnings of eight different velocity models that we used “a priori”. The model parameterization assumes a continuous velocity field between 4.5 km/s and 7.0 km/s until 30 km depth. The earth structure is represented in 3D by velocity at discrete points, and velocity at any intervening point is determined by linear interpolation among the surrounding eight grid points. A preliminary analysis of the resolution capabilities of the dataset, based on the Derivative Weight Sum (DWS) distribution, shows that the velocity structure is better resolved in the West part of the region between the surface to15 km. The resulting tomographic image has a prominent low-velocity anomaly that shows a maximum decrease in P-wave velocity in the first 12 kms in the studied region. We also identified the occurrence of local seismic events of reduced magnitude not catalogued, in the neighbourhood of Almodôvar (low Alentejo). The spatial distribution of epicentres defines a NE-SW direction that coincides with the strike of the mapped geological faults of the region and issued from photo-interpretation. Is still expectable to refine the seismicity of the region of Almodôvar and establish more rigorously its role in the seismotectonic picture of the region. This work is expected to produce a more detailed knowledge of the structure of the crust over the region of Algarve, being able to identify seismogenic zones, potentially generators of significant seismic events and also the identification of zones of active faults

A common structural motif in thiamin pyrophosphate-binding enzymes

AbstractThe amino acid sequences of a wide range of enzymes that utilize thiamin pyrophosphate (TPP) as cofactor have been compared. A common sequence motif approximately 30 residues in length was detected, beginning with the highly conserved sequence -GDG- and concluding with the highly conserved sequence -NN-. Secondary structure predictions suggest that the motif may adopt a βαβ fold. The same motif was recognised in the primary structure of a protein deduced from the DNA sequence of a hitherto unassigned open reading frame of Rhodobacter capsulata. This putative protein exhibits additional homology with some but not all of the TPP-binding enzymes

Alterations in brain connectivity due to plasticity and synaptic delay

Brain plasticity refers to brain's ability to change neuronal connections, as a result of environmental stimuli, new experiences, or damage. In this work, we study the effects of the synaptic delay on both the coupling strengths and synchronisation in a neuronal network with synaptic plasticity. We build a network of Hodgkin-Huxley neurons, where the plasticity is given by the Hebbian rules. We verify that without time delay the excitatory synapses became stronger from the high frequency to low frequency neurons and the inhibitory synapses increases in the opposite way, when the delay is increased the network presents a non-trivial topology. Regarding the synchronisation, only for small values of the synaptic delay this phenomenon is observed

LIQUID METAL FLOW CONTROL BY DC ELECTROMAGNETIC PUMPS

The cooling system of high-density thermal power requires fluids of high thermal conductivity, such as liquid metals. Electromagnetic pumps can be used to liquid metal fluid flow control in cooling circuits. The operation of electromagnetic pumps used to flow control is based on Lorentz force. This force can be achieved by magnetic field and electric current interaction, controlled by external independent power supplies. This work presents the electromagnetic pump operational principles, the IEAv development scheme and the BEMC-1 simulation code. The theoretical results of BEMC-1simulation are compared to electromagnetic pump operation experimental data, validating the BEMC-1 code. This code is used to evaluate the DC electromagnetic pump performance applied to Mercury flow control and others liquid metal such as Sodium, Lead and Bismuth, used in nuclear fast reactors

A PARAMETRIC STUDY AND PERFORMANCE EVALUATION OF DC ELECTROMAGNETIC PUMPS WITH BEMC-1 CODE

Electromagnetic pumps are used to control liquid metal fluid flow in cooling loops. The principle of operation of an electromagnetic pump is based on Lorentz’s force. This is obtained by interaction of the magnetic field and the electrical current, imposed and adjusted by independent external electric power sources. In this work are presented the continuous current electromagnetic pumps, their basic equations and the BEMC-1 code, developed for design and performance evaluation of a DC electromagnetic pump. The main objective of this paper is a parametric study for magnetic induction, static pressure, fluid flow and performance evaluation of the pump. The theoretical results are compared with the experimental data to get adjust factors to be used in the BEMC-1 code. In this way the BEMC-1 code can be validated and used in the evaluations and projects of DC electromagnetic pumps

Process monitoring during AlNxOy deposition by reactive magnetron sputtering and correlation with the film’s properties

In this work, AlNxOy thin films were deposited by reactive magnetron sputtering, using an aluminum target and an Ar/(N2+O2) atmosphere. The DC magnetron discharge parameters during the deposition process were investigated by optical emission spectroscopy and a plasma floating probe was used. The discharge voltage, the electron temperature, the ion flux and the optical emission lines were recorded for different reactive gas flows, near the target and close to the substrate. This information was correlated with the structural features of the deposits as a first step in the development of a system to control the structure and properties of the films during reactive magnetron sputtering. As the target becomes poisoned, the discharge voltage suffers an important variation, due to the modification of the secondary electron emission coefficient of the target, which is also supported by the evolution of the electron temperature and ion flux to the target. The sputtering yield of the target was also affected, leading to a reduction of the amount of Al atoms arriving to the substrate, according to optical emission spectroscopy results for Al emission line intensity. This behavior, together with the increase of non-metallic elements in the films, allowed obtaining different microstructures, over a wide range of compositions, which induced different electrical and optical responses of films.This research was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011. J. Borges also acknowledges FCT financial support under PhD grant Nº SFRH/BD/47118/2008 (financiado por POPH – QREN – Tipologia 4.1 – Formação Avançada, comparticipado pelo Fundo Social Europeu e por fundos nacionais do MCTES)

Virial coefficients from 2+1 dimensional QED effective actions at finite temperature and density

From spinor and scalar 2+1 dimensional QED effective actions at finite temperature and density in a constant magnetic field background, we calculate the corresponding virial coefficients for particles in the lowest Landau level. These coefficients depend on a parameter theta related to the time-component of the gauge field, which plays an essential role for large gauge invariance. The variation of the parameter theta might lead to an interpolation between fermionic and bosonic virial coefficients, although these coefficients are singular for theta=pi/2.Comment: 10 Latex pages, no figures. Version to appear in MPL

Perfil fermentativo das silagens de seis genótipos de sorgo ("Sorghum bicolor (L.) Moench. ") 1. MS; PB; N-NH3 e pH.

O presente trabalho teve como objetivo estudar o efeito do intervalo de abertura de silos sobre o perfil fermentativo de silagens de seis genótipos de sorgo (BR 700, BRS 610, 0249311, 0249313,0249345 e 0249351). Foram avaliados os parâmetros de matéria seca (MS), proteína bruta (PB), nitrogênio amoniacal (%N-NH3/NT) e pH das silagens. Os materiais foram plantados na EMBRAPA Milho e Sorgo, ensilados em silos de laboratório e analisados após, um, três, cinco, sete, 14, 28 e 56 dias de fermentação no Laboratório de Nutrição Animal da Escola de Veterinária da UFMG. Os valores de MS, PB, N-NH3 e pH das silagens variaram de 26,77 a 39,49%; 6,28 a 7,1%; 1,25 a 3,31%; 3,84 a 4,02%, respectivamente. As silagens dos seis genótipos de sorgo apresentaram adequados teores de MS, PB, N-NH3 e pH

Perfil de fermentação das silagens de seis genótipos de sorgo ("Sorghum bicolor (L.) Moench.") - Ácidos orgânicos.

Foram determinados os valores de ácidos orgânicos das silagens de seis genótipos de sorgo (BR 700, BRS 61O, 0249311, 0249313 ,0249345 e 0249351). Os materiais foram plantados na EMBRAPA Milho e Sorgo, ensilados em silos de laboratório e analisados após, 1, 3, 5, 7, 14, 28 e 56 dias de fermentação no Laboratório de Nutrição Animal da Escola de Veterinária da UFMG. Os teores dos ácidos lático, propiônico e acético variaram, respectivamente de 4,21 a 6,31%, de 0,28 a 0,33% e de 0,01 a 0,06%. Após 56 dias de fermentação os valores médios para ácido lático, propiônico e acético foram de 7,74%, 0,36% e 0,04%, respectivamente. As silagens dos seis genótipos de sorgo apresentaram adequados teores de ácidos orgânicos