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Sao Carlos, Brazil

The Federal University of São Carlos is a public research university located in São Carlos, state of São Paulo, Brazil. Wikipedia.

Martins M.J.,Federal University of Sao Carlos
Nuclear Physics B | Year: 2015

We have found a family of solvable nineteen vertex model with statistical configurations invariant by the time reversal symmetry within a systematic study of the respective Yang-Baxter relation. The Boltzmann weights sit on a degree seven algebraic threefold which is shown birationally equivalent to the three-dimensional projective space. This permits to write parameterized expressions for both the transition operator and the R-matrix depending on three independent affine spectral parameters. The Hamiltonian limit tells us that the azimuthal magnetic field term is connected with the asymmetry among two types of spectral variables. The absence of magnetic field defines a physical submanifold whose geometrical properties are remarkably shown to be governed by a quartic K3 surface. This expands considerably the class of irrational manifolds that could emerge in the theory of quantum integrable models. © 2015 The Author. Source

Novaes M.,Federal University of Sao Carlos
Annals of Physics | Year: 2011

We obtain explicit expressions for positive integer moments of the probability density of eigenvalues of the Jacobi and Laguerre random matrix ensembles, in the asymptotic regime of large dimension. These densities are closely related to the Selberg and Selberg-like multidimensional integrals. Our method of solution is combinatorial: it consists in the enumeration of certain classes of lattice paths associated to the solution of recurrence relations. © 2010 Elsevier Inc. Source

Canto L.B.,Federal University of Sao Carlos
Polymer Testing | Year: 2014

The coarsening of the phase morphology of polypropylene (PP) blends, containing 20 wt% of the copolymer ethylene vinyl acetate (EVA) as the dispersed phase, during compounding in a co-rotating twin screw extruder (Co-TSE) was investigated. Blending was performed by applying a fixed screw profile, temperature and screw rotation speed, with various flow rates, which allowed identification of the effect of the residence time on the blend morphology. The average EVA particle size increased linearly with the mean extrusion residence time. From this relationship, the coarsening kinetics, including the minimum droplet size that would be obtained and the coarsening rate due to the domination of coalescence over droplet breakup during extrusion, was quantified. The data reported herein provide greater insight into Wu's theory for the prediction of the droplet size in polymer blends compounded in a Co-TSE. © 2014 Elsevier Ltd. All rights reserved. Source

Martins M.J.,Federal University of Sao Carlos
Nuclear Physics B | Year: 2013

We investigate the Yang-Baxter algebra for U(1) invariant three-state vertex models whose Boltzmann weights configurations break explicitly the parity-time reversal symmetry. We uncover two families of regular Lax operators with nineteen non-null weights which ultimately sit on algebraic plane curves with genus five. We argue that these curves admit degree two morphisms onto elliptic curves and thus they are bielliptic. The associated R-matrices are non-additive in the spectral parameters and it has been checked that they satisfy the Yang-Baxter equation. The respective integrable quantum spin-1 Hamiltonians are exhibited. © 2013. Source

Zanotto E.D.,Federal University of Sao Carlos
International Journal of Applied Glass Science | Year: 2013

Over the past 36 years, our research has mainly focused on the crystallization kinetics and properties of glasses and glass-ceramics. A sampling of the most conclusive papers are reviewed here and include the following topics: the effects of liquid phase separation on crystal nucleation; tests and development of models of crystal nucleation, growth, and overall crystallization; metastable phase formation; surface crystallization; glass stability against devitrification; glass-forming ability; possible correlations between the molecular structure and the nucleation mechanism; sintering with concurrent surface crystallization; and diffusional processes that control crystallization. We conclude that despite significant advancement in the knowledge about several aspects of phase transformations in glasses that resulted from our own research and of other groups, which is not described in this review, glass crystallization remains an open, rich field to be explored. © 2013 The American Ceramic Society and Wiley Periodicals, Inc. Source

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