Juiz de fora, Brazil
Juiz de fora, Brazil

The Federal University of Juiz de Fora is a university in Brazil. Throughout its over 50 years of existence, the university has undergone significant growth, strengthening the quality of undergraduate and graduate education while maintaining its role as an agent of community development. Wikipedia.


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Shapiro I.L.,University of Geneva | Shapiro I.L.,Federal University of Juiz de fora | Shapiro I.L.,Tomsk State Pedagogical University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

In the recently proposed non-local theory of quantum gravity one can avoid massive tensor ghosts at the tree level by introducing an exponential form factor between the two Ricci tensors. We show that at the quantum level this theory has an infinite amount of massive unphysical states, mostly corresponding to complex poles. © 2015 The Author.


Melo R.C.N.,Federal University of Juiz de fora | Dvorak A.M.,Beth Israel Deaconess Medical Center
PLoS Pathogens | Year: 2012

Phagocytosis of invading microorganisms by specialized cells such as macrophages and neutrophils is a key component of the innate immune response. These cells capture and engulf pathogens and subsequently destroy them in intracellular vacuoles-the phagosomes. Pathogen phagocytosis and progression and maturation of pathogen-containing phagosomes, a crucial event to acquire microbicidal features, occurs in parallel with accentuated formation of lipid-rich organelles, termed lipid bodies (LBs), or lipid droplets. Experimental and clinical infections with different pathogens such as bacteria, parasites, and viruses induce LB accumulation in cells from the immune system. Within these cells, LBs synthesize and store inflammatory mediators and are considered structural markers of inflammation. In addition to LB accumulation, interaction of these organelles with pathogen-containing phagosomes has increasingly been recognized in response to infections and may have implications in the outcome or survival of the microorganism within host cells. In this review, we summarize our current knowledge on the LB-phagosome interaction within cells from the immune system, with emphasis on macrophages, and discuss the functional meaning of this event during infectious diseases. © 2012 Melo, Dvorak.


Soares D.,Federal University of Juiz de fora
Computer Methods in Applied Mechanics and Engineering | Year: 2015

In this work, a new family of time-marching procedures for dynamics is introduced. The proposed algorithm is based on displacements-velocities relations, requiring no computation of accelerations. Thus, not only it is a very simple technique, but also it is truly self-starting. Unconditionally stable implicit and conditionally stable explicit approaches are focused here, and optimized procedures are discussed for these analyses. The new technique is second-order accurate with controllable period elongation and algorithmic dissipation. Numerical results are presented, illustrating the good performance of the method. The new family is simple, efficient and highly accurate, resulting in a very effective time-marching technique. © 2014.


Soares Jr. D.,Federal University of Juiz de fora
Computers and Structures | Year: 2011

In this work, a new family of time marching procedures based on Green's function matrices is presented. The formulation is based on the development of new recurrence relationships, which employ time integral terms to treat initial condition values. These integral terms are numerically evaluated taking into account Newton-Cotes formulas. The Green's matrices of the model are also numerically computed, taking into account the generalized-α method and subcycling techniques. As it is discussed and illustrated along the text, the proposed procedure is efficient and accurate, providing a very attractive time marching technique. © 2010 Elsevier Ltd. All rights reserved.


Soares Jr. D.,Federal University of Juiz de fora
Journal of Computational Physics | Year: 2013

In this work, smoothed meshfree methods are firstly applied to numerically analyze twodimensional electromagnetic wave propagation models. A weakened weak formulation based on the edges of triangular cells obtained by a Delaunay triangulation is considered here, framing the so-called edge-based smoothed domains. The meshfree shape functions are computed by the Radial Point Interpolation Method (RPIM) considering two schemes for the shape function support domains, namely the T3- and the T6-scheme. These schemes are based on the above mentioned triangular cells and they consider fixed numbers of nodes for the support domains. A new procedure to compute the transient related matrices is discussed here, aiming to be more consistent with the edge-based smoothed point interpolation method. In this new procedure, finer local integration techniques are managed to be considered at lower computational costs, rendering more accurate and efficient techniques. At the end of the paper, numerical examples are presented, illustrating the effectiveness and potentialities of the proposed methodologies. © 2012 Elsevier Inc.


Soares Jr. D.,Federal University of Juiz de fora
Computer Methods in Applied Mechanics and Engineering | Year: 2013

In this work, smoothed meshfree methods are firstly applied to numerically analyze nonlinear pore-dynamic models. A weakened weak formulation based on the edges of triangular cells obtained by a Delaunay triangulation is considered here, framing the so-called edge-based smoothed domains. The meshfree shape functions are computed by the radial point interpolation method considering the T6-scheme for the shape function support domains. Enhanced procedures to compute the mass, compressibility and coupling matrices of the pore-dynamic model are discussed, which are consistent with the computation of the stiffness and permeability matrices (as well as internal force vectors, in case of nonlinear analyses) of the edge-based smoothed domain formulation and that consider finer local integration techniques at lower computational costs, rendering more accurate and efficient procedures. Two numerical formulations are considered here to analyze the time-domain nonlinear coupled system of equations that arises once the spatial discretization is accomplished: the standard Newmark/Newton-Raphson method and an alternative iterative coupling approach. In this iterative approach, each phase of the coupled problem is treated separately, uncoupling the governing equations of the model; thus, smaller and better conditioned systems of equations are obtained, rendering more attractive techniques. A relaxation parameter is introduced in order to improve the efficiency of the iterative coupling procedure and an expression to compute optimal values for the relaxation parameter is discussed. At the end of the paper, numerical examples are presented, illustrating the effectiveness and potentialities of the proposed methodologies. © 2012 Elsevier B.V.


Mund J.,Federal University of Juiz de fora
Communications in Mathematical Physics | Year: 2012

We consider a purely massive local relativistic quantum theory specified by a family of von Neumann algebras indexed by the space-time regions. We assume that, affiliated with the algebras associated to wedge regions, there are operators which create only single particle states from the vacuum (so-called polarization-free generators) and are well-behaved under the space-time translations. Strengthening a result of Borchers, Buchholz and Schroer, we show that then the theory is unitarily equivalent to that of a free field for the corresponding particle type. We admit particles with any spin and localization of the charge in space-like cones, thereby covering the case of string-localized covariant quantum fields. © 2012 Springer-Verlag.


Deriglazov A.A.,Federal University of Juiz de fora
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2012

We construct a non-Grassmann spinning-particle model which, by analogy with quantum mechanics, does not admit the notion of a trajectory within the position space. The pseudo-classical character of the model allows us to avoid the inconsistencies arising in the quantum-mechanical interpretation of a one-particle sector of the Dirac equation. © 2012 Elsevier B.V.


Deriglazov A.A.,Federal University of Juiz de fora
Annals of Physics | Year: 2012

We propose a relativistic particle model without Grassmann variables which, being canonically quantized, leads to the Dirac equation. Both Γ-matrices and the relativistic spin tensor are produced through the canonical quantization of the classical variables which parametrize the properly constructed relativistic spin surface. Although there is no mass-shell constraint in our model, our particle's speed cannot exceed the speed of light. The classical dynamics of the model is in correspondence with the dynamics of mean values of the corresponding operators in the Dirac theory. In particular, the position variable experiences Zitterbewegung in noninteracting theory. The classical equations for the spin tensor are the same as those of the Barut-Zanghi model of a spinning particle. © 2011 Elsevier Inc.


Deriglazov A.A.,Federal University of Juiz de fora
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2012

We construct the relativistic particle model without Grassmann variables which meets the following requirements. A) Canonical quantization of the model implies the Dirac equation. B) The variable which experiences Zitterbewegung, represents a gauge non-invariant variable in our model. Hence our particle does not experience the undesirable Zitterbewegung. C) In the non-relativistic limit spin is described by three-vector, as it could be expected. © 2011 Elsevier B.V. All rights reserved.

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