Modified Bethe-Weizsacker mass formula with isotonic shift and new driplines

Nuclear masses are calculated using the modified Bethe-Weizsacker mass formula in which the isotonic shifts have been incorporated. The results are compared with the improved liquid drop model with isotonic shift. Mass excesses predicted by this method compares well with the microscopic-macroscopic model while being much more simple. The neutron and proton drip lines have been predicted using this modified Bethe-Weizsacker mass formula with isotonic shifts.Comment: 9 pages including 2 figure

Estoque e produção de serapilheira sobre o solo em sistema agroflorestal sob influência de árvores de ingá (Ingá edulis) e cacau (Theobroma cacao) no município de Tomé-Açu (PA).

O objetivo do trabalho foi quantificar e comparar a variação temporal ao longo de quatro meses quanto ao acúmulo e produção de serapilheira de árvores de ingá e cacau em um sistema agroflorestal, situado no município de Tomé Açu - PA. A quantidade de serapilheira do solo foi estimada através de quadrantes de 0,5m X 0,5m. A produção de serapilheira foi estimada através da instalação de coletores com 1m2, suspenso a 15 cm do solo. O material foi coletado em sacos de papel, identificados e separados em frações (material lenhoso, não lenhoso e total) e em seguida secas em estufa de 65ºC por 48 horas e pesadas em balança digital com precisão de 0,01 g. O estoque e a produção de serapilheira se diferenciaram entre espécie, tempo e frações. Maiores resultados puderam ser observados na espécie de Ingá em relação à espécie de Cacau, em meses secos e com maior contribuição da fração não lenhosa

Quadratic Effective Action for QED in D=2,3 Dimensions

We calculate the effective action for Quantum Electrodynamics (QED) in D=2,3 dimensions at the quadratic approximation in the gauge fields. We analyse the analytic structure of the corresponding nonlocal boson propagators nonperturbatively in k/m. In two dimensions for any nonzero fermion mass, we end up with one massless pole for the gauge boson . We also calculate in D=2 the effective potential between two static charges separated by a distance L and find it to be a linearly increasing function of L in agreement with the bosonized theory (massive Sine-Gordon model). In three dimensions we find nonperturbatively in k/m one massive pole in the effective bosonic action leading to screening. Fitting the numerical results we derive a simple expression for the functional dependence of the boson mass upon the dimensionless parameter e^{2}/m .Comment: 10 pages, 2 figure

Reentrant valence transition in EuO at high pressures: beyond the bond-valence model

The pressure-dependent relation between Eu valence and lattice structure in model compound EuO is studied with synchrotron-based x-ray spectroscopic and diffraction techniques. Contrary to expectation, a 7% volume collapse at $\approx$ 45 GPa is accompanied by a reentrant Eu valence transition into a \emph{lower} valence state. In addition to highlighting the need for probing both structure and electronic states directly when valence information is sought in mixed-valent systems, the results also show that widely used bond-valence methods fail to quantitatively describe the complex electronic valence behavior of EuO under pressure.Comment: 5 pages, 4 figure

Proposta metodológica para a geração de modelo de elevação digital a partir de cartas topográficas: uma abordagem no contexto do projeto GeoDegrade.

O projeto GeoDegrade tem como objetivo desenvolver geotecnologias para a identificação e o monitoramento de níveis de degradação em pastagens, sendo que um dos métodos contemplados no projeto é a integração de plataformas de informações de variáveis biofísicas. Por meio da sobreposição do MDE e suas informações intrínsecas (classes de declividades, comprimento das vertentes e áreas das vertentes) às demais plataformas de informação (mapa de solo, uso e cobertura vegetal e balanço hídrico da região) é possível descrever o potencial de erodibilidade do solo e sua influência nos processos de degradação das pastagens.bitstream/item/83479/1/034-12.pd

Temperature oscillations of magnetization observed in nanofluid ferromagnetic graphite

We report on unusual magnetic properties observed in the nanofluid room-temperature ferromagnetic graphite (with an average particle size of l=10nm). More precisely, the measured magnetization exhibits a low-temperature anomaly (attributed to manifestation of finite size effects below the quantum temperature) as well as pronounced temperature oscillations above T=50K (attributed to manifestation of the hard-sphere type pair correlations between ferromagnetic particles in the nanofluid)

Spectral and Fermi surface properties from Wannier interpolation

We present an efficient first-principles approach for calculating Fermi surface averages and spectral properties of solids, and use it to compute the low-field Hall coefficient of several cubic metals and the magnetic circular dichroism of iron. The first step is to perform a conventional first-principles calculation and store the low-lying Bloch functions evaluated on a uniform grid of k-points in the Brillouin zone. We then map those states onto a set of maximally-localized Wannier functions, and evaluate the matrix elements of the Hamiltonian and the other needed operators between the Wannier orbitals, thus setting up an ``exact tight-binding model.'' In this compact representation the k-space quantities are evaluated inexpensively using a generalized Slater-Koster interpolation. Because of the strong localization of the Wannier orbitals in real space, the smoothness and accuracy of the k-space interpolation increases rapidly with the number of grid points originally used to construct the Wannier functions. This allows k-space integrals to be performed with ab-initio accuracy at low cost. In the Wannier representation, band gradients, effective masses, and other k-derivatives needed for transport and optical coefficients can be evaluated analytically, producing numerically stable results even at band crossings and near weak avoided crossings.Comment: 12 pages, 7 figure

Status and performances of the FAZIA project

FAZIA is designed for detailed studies of the isospin degree of freedom, extending to the limits the isotopic identification of charged products from nuclear collisions when using silicon detectors and CsI(Tl) scintillators. We show that the FAZIA telescopes give isotopic identification up to Z$\sim$25 with a $\Delta$E-E technique. Digital Pulse Shape Analysis makes possible elemental identification up to Z=55 and isotopic identification for Z=1-10 when using the response of a single silicon detector. The project is now in the phase of building a demonstrator comprising about 200 telescopes