Numerical method for the mixed Volterra-Fredholm integral equations using hybrid Legendre functions

summary:A new method is proposed for the numerical solution of linear mixed Volterra-Fredholm integral equations in one space variable. The proposed numerical algorithm combines the trapezoidal rule, for the integration in time, with piecewise polynomial approximation, for the space discretization. We extend the method to nonlinear mixed Volterra-Fredholm integral equations. Finally, the method is tested on a number of problems and numerical results are given

Efeito do pH e do desengorduramento na qualidade do néctar misto de açaí e cupuaçu.

A utilização da polpa de açaí em néctares representa uma boa alternativa para agregar valor ao fruto, e a associação com a polpa de cupuaçu, que apresenta elevada acidez, permite reduzir o pH do produto final sem o uso de aditivos. Os objetivo do trabalho foram avaliar o efeito do pH na qualidade do néctar misto de açaí e cupuaçu e avaliar a vida de prateleira de um néctar misto com baixo teor de gordura. Na primeira etapa, foram elaborados néctares com polpas de cupuaçu de diferentes pHs (A=3,2, B=3,0, C=2,8, D=2,6). Na segunda etapa, foram elaborados néctares com polpa de açaí previamente desengordurada por centrifugação em escala piloto. Foi estudada a vida de prateleira por um período de 4 meses. Os produtos finais foram analisados quanto a composição química, pH, acidez titulável, cor instrumental, sólidos solúveis, microbiologia (coliformes totais e salmonella) e aceitação sensorial. Todos os néctares obtidos estavam em conformidade com os requisitos microbiológicos legais. Os néctares com menor pH final (C e D) apresentaram maior intensidade de cor vermelha, mas o néctar com o maior pH (A) foi melhor avaliado sensorialmente em relação ao sabor e impressão global. Em relação à vida de prateleira do néctar com baixo teor de gordura, verificou-se que o teor de antocianinas e a intensidade da cor vermelha diminuíram com o tempo, não havendo diferença em relação às demais características. As amostras apresentaram boa aceitação sensorial durante o período estudado, com notas superiores a 6 para todos os atributos testados. Apesar disso, ocorreu degradação das antocianinas, o que prejudicou o valor nutricional e a cor do produto

Poster: Reengineering legacy systems for supporting SOA: A case study on the brazilian's secretary of state for taxation

© 2018 Authors. The migration of legacy systems to a service-oriented architecture (SOA) allows to deal with the demand for interoperability and the need to provide a robust high-Available service interface. However, such migration presents a considerable risk, as it often involves the use of different techniques on systems with elevated technical debt and high maintenance costs. For this purpose, a process is instantiated to provide an appropriate set of techniques that will minimize risks and at the same time ensure quality improvement of the systems throughout the migration process. In this sense, this work reports on a case study of the application of a process for the reengineering of legacy systems to support the implementation of SOA project. This study has been applied to the evolution of legacy systems of the Secretariat of State for Taxation of Rio Grande do Norte (SET/RN), Brazil, providing significant results regarding the achievement of important quality goals

Complementary Constraints on Brane Cosmology

The acceleration of the expansion of the universe represents one of the major challenges to our current understanding of fundamental physics. In principle, to explain this phenomenon, at least two different routes may be followed: either adjusting the energy content of the Universe -- by introducing a negative-pressure dark energy -- or modifying gravity at very large scales -- by introducing new spatial dimensions, an idea also required by unification theories. In the cosmological context, the role of such extra dimensions as the source of the dark pressure responsable for the acceleration of our Universe is translated into the so-called brane world (BW) cosmologies. Here we study complementary constraints on a particular class of BW scenarios in which the modification of gravity arises due to a gravitational \emph{leakage} into extra dimensions. To this end, we use the most recent Chandra measurements of the X-ray gas mass fraction in galaxy clusters, the WMAP determinations of the baryon density parameter, measurements of the Hubble parameter from the \emph{HST}, and the current supernova data. In agreement with other recent results, it is shown that these models provide a good description for these complementary data, although a closed scenario is always favored in the joint analysis. We emphasize that observational tests of BW scenarios constitute a natural verification of the role of possible extra dimensions in both fundamental physics and cosmology.Comment: 6 Pages, 4 Figures, LaTe

Angular dependence of the bulk nucleation field Hc2 of aligned MgB2 crystallites

Studies on the new MgB2 superconductor, with a critical temperature Tc ~ 39 K, have evidenced its potential for applications although intense magnetic relaxation effects limit the critical current density, Jc, at high magnetic fields. This means that effective pinning centers must be added into the material microstructure, in order to halt dissipative flux movements. Concerning the basic microscopic mechanism to explain the superconductivity in MgB2, several experimental and theoretical works have pointed to the relevance of a phonon-mediated interaction, in the framework of the BCS theory. Questions have been raised about the relevant phonon modes, and the gap and Fermi surface anisotropies, in an effort to interpret spectroscopic and thermal data that give values between 2.4 and 4.5 for the gap energy ratio. Preliminary results on the anisotropy of Hc2 have shown a ratio, between the in-plane and perpendicular directions, around 1.7 for aligned MgB2 crystallites and 1.8 for epitaxial thin films. Here we show a study on the angular dependence of Hc2 pointing to a Fermi velocity anisotropy around 2.5. This anisotropy certainly implies the use of texturization techniques to optimize Jc in MgB2 wires and other polycrystalline components.Comment: 10 pages + 4 Figs.; Revised version accepted in Phys. Rev.

Search for low lying dipole strength in the neutron rich nucleus 26^{26}Ne

Coulomb excitation of the exotic neutron-rich nucleus $^{26}$Ne on a $^{nat}$Pb target was measured at 58 A.MeV in order to search for low-lying E1 strength above the neutron emission threshold. Data were also taken on an $^{nat}$Al target to estimate the nuclear contribution. The radioactive beam was produced by fragmentation of a 95 A.MeV $^{40}$Ar beam delivered by the RIKEN Research Facility. The set-up included a NaI gamma-ray array, a charged fragment hodoscope and a neutron wall. Using the invariant mass method in the $^{25}$Ne+n channel, we observe a sizable amount of E1 strength between 6 and 10 MeV. The reconstructed $^{26}$Ne angular distribution confirms its E1 nature. A reduced dipole transition probability of B(E1)=0.49$\pm$0.16 $e^2fm^2$ is deduced. For the first time, the decay pattern of low-lying strength in a neutron-rich nucleus is obtained. The results are discussed in terms of a pygmy resonance centered around 9 MeV

Higher spin fields and the problem of cosmological constant

The cosmological evolution of free massless vector or tensor (but not gauge) fields minimally coupled to gravity is analyzed. It is shown that there are some unstable solutions for these fields in De Sitter background. The back reaction of the energy-momentum tensor of such solutions to the original cosmological constant exactly cancels the latter and the expansion regime changes from the exponential to the power law one. In contrast to the adjustment mechanism realized by a scalar field the gravitational coupling constant in this model is time-independent and the resulting cosmology may resemble the realistic one.Comment: 15 pages, Latex twic