935 resultados para Relation between professional insertion and training


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In this letter, the authors propose that photoluminescence emission in CaTiO3 is affected not only by disorder in the lattice former but also by structural disorder in the lattice modifier. Structural disorder was evaluated by Ti, Ca K-edge x-ray absorption near-edge structure experiments and by photoluminescence emission. The preedge feature of the Ca K edge was related to the intensity of photoluminescence emission. The results of the preedge feature of the Ca K-edge x-ray absorption near-edge structure confirm the presence of different Ca coordination numbers, namely, Ca-O-11 and Ca-O-12. (c) 2007 American Institute of Physics.

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We describe a new physicochemical descriptor of the antioxidant activity of phenols, the energy difference between the two highest occupied molecular orbitals, which we believe will improve quantitative structure-activity relationship studies about these compounds. (C) 2003 Wiley Periodicals, Inc.

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The electrical characteristics of oxidized poly(thionaphtheneindole) were investigated as a function of ambient relative humidity (r.h.). The current flowing through a pressed pellet of material between two massive gold electrodes plotted against voltage gives a wave-shaped curve with a halfwave potential at V = similar to 3 V. The current recorded at 4 V (plateau of the wave) is a sigmoidal function of r.h, with the inflexion point at similar to 60%. An interpretation of these findings is given, based on the influence of water on the dielectric constant of the material and on acid-base equilibrium between poly(thionaphtheneindole) and water, from which protons are produced. The behaviour of poly (thionaphtheneindole) as the active component of an amperometric humidity sensor is also reported.

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Six groups of 6 rats received equal doses (0.8 ml/100 g of body weight) of different rabbit anti rat kidney sera. The titer of anti GBM antibodies in the sera was evaluated by indirect immunofluorescent test in isolated GBM (IIT GBM). Rats of groups 1, 2, 3, 5, 6 received anti rat GBM sera with titers of 1/320, 1/240, 1/160, 1/60, 1/30 respectively. Group 4 received anti rat kidney serum with a titer of 1/80. The rats of group 1 died from 1 to 5 minutes after inoculation and their kidney were congested, with hialine trombi occluding arterioles and glomerular capillaries. The rats of group 2 and one of group 3 died from 2 to 15 days after inoculation and diffuse cortical necrosis was found. The remaining rats were sacrificed 2 months after inoculation. The kidneys were normal in control group; chronic membranoproliferative glomerulonephritis was observed in group 3 and 4, membranoproliferative glomerulonephritis in group 5 and minimal changes in group 6. By immunofluorescence rabbit gammaglobulin was seen in GBM of group 3, 4, 5 and 6. The IIT GBM performed in the eluates of the kidneys revealed the presence of heterologous antibody in groups 1, 2, 3, 4, 5 and 6 and autologous antibody in groups 3, 4 and 5. One concludes that the IIT GBM identifies and quantifies antibodies which have the property of damaging the kidney.

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Increased urbanization typically leads to an increase in abundance of a few species and a reduction in bird species richness. Understanding the structure of biotic communities in urban areas will allow us to propose management techniques and to decrease conflicts between wild species and human beings. The objective of this study was to describe the structure of the bird community in an urban ecosystem. The study was carried out in the city of Taubaté in southeastern Brazil. Point-counts were established in areas with different levels of tree density ranging from urban green spaces to predominantly built-up areas. We looked for a correlation between the richness/abundance of birds and the size of the area surveyed, the number of houses, the number of tree species and the number of individual trees. The results of multiple regression showed that bird richness had a direct relationship with vegetation complexity. The abundance and diversity of tree species were better predictors of bird species than the number of houses and size of the area surveyed. We discuss implications of this study for conservation and management of bird diversity in urban areas, such as the need to increase green areas containing a large diversity of native plant species. © 2011 Springer Science+Business Media, LLC.

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Reverse Logistics activities are practiced by most Brazilian companies. However, a relevant problem is to identify how different Reverse Logistics programs can affect corporate performance indicators. Analytic Network Process is one of the analytical tools, which can be used to handle a multi-criteria decision-making problem and it is the only one that can capture the interdependencies between the criteria under consideration. This method was adopted here to study the influence of Reverse Logistics practices in corporate performance. Preliminary results indicated that the method can be used, reaching a result compatible to the reality of the Brazilian companies.

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A simple hybrid synthesis processing method was developed to synthesize γ-MnO2 nanocrystalline particles. The polyol method was modified by the addition of nitric acid in order to allow the synthesizing of single-phase Mn3O4 in a large scale. In the sequence, the acid digestion technique was used to transform Mn3O4 into γ-MnO2. Structural and morphological characterization was carried out by X-ray diffractometry, Infrared and Raman spectroscopy, thermogravimetric analysis, nitrogen adsorption isotherm, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements. The synthesized material exhibits a specific capacitance of 125.1 F g-1 at a mass loading of 0.98 mg cm-2. The relation between structural features and electrochemical activity is discussed by comparing the synthesized material with commercial electrolytic manganese dioxide. © 2013 Springer-Verlag Berlin Heidelberg.

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We have studied, using double ratio of QCD (spectral) sum rules, the ratio between the masses of Tcc and X(3872) assuming that they are respectively described by the D−D∗ and D− ¯D∗ molecular currents. We found (within our approximation) that the masses of these two states are almost degenerate. Since the pion exchange interaction between these mesons is exactly the same, we conclude that if the observed X(3872) meson is a D ¯D∗ + c.c. molecule, then the DD∗ molecule should also exist with approximately the same mass. An extension of the analysis to the b-quark case leads to the same conclusion. We also study the SU(3) breakings for the T s Q Q /TQ Q mass ratios. Motivated by the recent Belle observation of two Zb states, we revise our determination of Xb by combining results from exponential and FESR sum rules.

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Thermal screening masses related to the conserved vector current are determined for the case that the current carries a non-zero Matsubara frequency, both in a weak-coupling approach and through lattice QCD. We point out that such screening masses are sensitive to the same infrared physics as light-cone real-time rates. In particular, on the perturbative side, the inhomogeneous Schrödinger equation determining screening correlators is shown to have the same general form as the equation implementing LPM resummation for the soft-dilepton and photon production rates from a hot QCD plasma. The static potential appearing in the equation is identical to that whose soft part has been determined up to NLO and on the lattice in the context of jet quenching. Numerical results based on this potential suggest that screening masses overshoot the free results (multiples of 2πT) more strongly than at zero Matsubara frequency. Four-dimensional lattice simulations in two-flavour QCD at temperatures of 250 and 340 MeV confirm the non-static screening masses at the 10% level. Overall our results lend support to studies of jet quenching based on the same potential at T ≳ 250 MeV.