927 resultados para Dependência - Dependence


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We report on measurements of the adiabatic second-order elastic constants of the off-stoichiometric Ni54Mn23Al23 single-crystalline Heusler alloy. The variation in the temperature dependence of the elastic constants has been investigated across the magnetic transition and over a broad temperature range. Anomalies in the temperature behavior of the elastic constants have been found in the vicinity of the magnetic phase transition. Measurements under applied magnetic field, both isothermal and variable temperature, show that the value of the elastic constants depends on magnetic order, thus giving evidence for magnetoelastic coupling in this alloy system.

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The electronic structure and properties of cerium oxides (CeO2 and Ce2O3) have been studied in the framework of the LDA+U and GGA(PW91)+U implementations of density functional theory. The dependence of selected observables of these materials on the effective U parameter has been investigated in detail. The examined properties include lattice constants, bulk moduli, density of states, and formation energies of CeO2 and Ce2O3. For CeO2, the LDA+U results are in better agreement with experiment than the GGA+U results whereas for the computationally more demanding Ce2O3 both approaches give comparable accuracy. Furthermore, as expected, Ce2O3 is much more sensitive to the choice of the U value. Generally, the PW91 functional provides an optimal agreement with experiment at lower U energies than LDA does. In order to achieve a balanced description of both kinds of materials, and also of nonstoichiometric CeO2¿x phases, an appropriate choice of U is suggested for LDA+U and GGA+U schemes. Nevertheless, an optimum value appears to be property dependent, especially for Ce2O3. Optimum U values are found to be, in general, larger than values determined previously in a self-consistent way.

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The remarkable difference between the nuclear quadrupole frequencies v_Q of Cu(1) and Cu(2) in YBa_2Cu_3O_6 and YBa_2Cu_3O_7 is analyzed. We calculate the ionic contribution to the electric field gradients and estimate, by using experimental results for Cu_2O and La_2CuO_4, the contribution of the d valence electrons. Thus, we determine v_Q1, v_Q2, and the asymmetry parameter η for YBa_2Cu_3O_6 and YBa_2Cu_3O_7. The number of holes in dthe Cu-O planes and chains is found to be important for the different behavior of v_Q1 and v_Q2.

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We present a theory which permits for the first time a detailed analysis of the dependence of the absorption spectrum on atomic structure and cluster size. Thus, we determine the development of the collective excitations in small clusters and show that their broadening depends sensitively on the tomic structure, in particular at the surface. Results for Hg_n^+ clusters show that the plasmon energy is close to its jellium value in the case of spherical-like structures, but is in general between w_p/ \wurzel{3} and w_p/ \wurzel{2} for compact clusters. A particular success of our theory is the identification of the excitations contributing to the absorption peaks.

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Within the quasimolecular (MO) kinematic dipole model we predict a strong dependence of the anisotropy of the MO radiation on the orientation of the heavy ion scattering plane relative to the direction of the photon detection plane.

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from Thos. Bartlett's anthology

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This participatory action research was based on a experience of educational intervention on La Cruz and Bello Oriente (Manrique-Medellin), a marginal zone in the northeastern part of the Commune 3 in Medellin,. Colombia. In this marginal sector, psychosocial problems seem to be associated to limited educational and employment opportunities, domestic violence, illegal armed forces, sexual abuse, social discrimination, and lack of adequate public services, among others.  All these are also considered as risk factors for drug dependency.  We used a structured interview designed to identify leisure tendencies, use of free time, and tendencies in recreational activities. Data from the interview were triangulated with information collected by observation and in field work and used to build a psycho-pedagogic method based on play and leisure activities. The effects of the use of this educational intervention on the satisfaction of human needs were analyzed in light of the theory of Manfred Max-Neef. Results point out the need for new educational strategies aimed to promote creativity, solidarity, mental, physical and social health, more enthusiasm and motivation and in general, positive attitudes that help prevent drug dependence.

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Desvalorização pelo atraso (DA) se refere à escolha especialmente influenciada pelo grau de imediaticidade com que um bem é liberado, havendo a diminuição de sua preferência em função do atraso em sua liberação. A DA se relaciona de forma positiva com a impulsividade e está presente em portadores de diversos tipos de dependências químicas e de outros transtornos que envolvem a impulsividade. Este artigo tem como objetivo apresentar a DA e sua relação com a dependência química a partir de revisão de estudos que verificaram a relação entre ambos e a aplicabilidade dos resultados como medida de impulsividade. Os estudos demonstraram que a desvalorização se associa de forma significativa com o consumo de substâncias e revelaram que sua avaliação pode ser uma importante informação no processo de tomada de decisão no uso de substâncias. Apresentam-se também estratégias de intervenção capazes de controlar e modificar a DA.

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We design a financial network model that explicitly incorporates linkages across institutions through a direct contagion channel, as well as an indirect common exposure channel. In particular, common exposure is setup so as to link the financial to the real sector. The model is calibrated to balance sheet data on the colombian financial sector. Results indicate that commercial banks are the most systemically important financial institutions in the system. Whereas government owned institutions are the most vulnerable institutions in the system.