oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 748 )

2018 ( 1087 )

2017 ( 1002 )

2016 ( 1469 )

Custom range...

Search Results: 1 - 10 of 665589 matches for " J. A. Rodrigues "
All listed articles are free for downloading (OA Articles)
Page 1 /665589
Display every page Item
Loop Space Hamiltonians And Field Theory Of Non-Critical Strings
A. Jevicki,J. Rodrigues
Physics , 1993, DOI: 10.1016/0550-3213(94)90329-8
Abstract: We consider the loop space representation of multi-matrix models. Explaining the origin of a time variable through stochastic quantization we make contact with recent proposals of Ishibashi and Kawai. We demonstrate how collective field theory with its loop space interactions generates a field theory of non-critical strings.
Satellite rings and normal modes in rotating clouds of ultra cold atoms
J. D. Rodrigues,J. T. Mendon?a,J. A. Rodrigues
Physics , 2014,
Abstract: The multiple scattering of light in a gas of ultra cold atoms is responsible for many exciting features observed in magneto-optical traps including the collective behavior forced by a Coulomb like potential. This field also induces plasma like phenomena in the cloud which allows the treatment of the system as a one component trapped plasma. With a fluid description and casting the thermodynamical behavior in the form of a polytropic equation of state we investigate the equilibrium profiles of rotating clouds and its dependence on the experiment characteristics. Numerical solutions predict the formation of stable orbital modes both in rotating and non rotating clouds. We also investigate the normal modes on such rotating systems.
Influência da forma e do processo de obten??o do entalhe na carga máxima e na energia de fratura de argamassas utilizando o método da cunha para propaga??o estável de trinca
Ribeiro, S.;Rodrigues, J. A.;
Ceramica , 2009, DOI: 10.1590/S0366-69132009000200011
Abstract: this paper discusses how the shape and preparation of the notch affect crack propagation in ceramic materials with heterogeneous microstructures and, as a result, the maximum load and fracture energy when these materials are subjected to loads using the wedge splitting test. mortars were prepared with portland cement, sand and water, which were mixed, molded, and cured at 25 oc for seven days. after curing, the samples were dried at 55 oc for 48 h. two mortar compositions were prepared with proportions of sand:cement of 3:1 and 2:1. two types of notches were tested: one with a square-tipped profile and the other v-shaped with a 60o angle. the square shaped notches were prepared in two ways: one mechanically with a diamond disc tool and the other using blades as cores during the molding of the mortars. a pvc mold equipped with internal steel blades was created to produce samples notched and grooved in the mortar molding process. stable conditions of crack propagation were established based on preliminary tests. the crack was found to propagate along an imaginary plane defined by the lateral grooves in the sample. the results indicated that the notch providing the best conditions of crack propagation stability is the v-shaped notch produced in the molding of the sample.
A comparative study of aging of the elastic fiber system of the diaphragm and the rectus abdominis muscles in rats
Rodrigues, C.J.;Rodrigues Junior, A.J.;
Brazilian Journal of Medical and Biological Research , 2000, DOI: 10.1590/S0100-879X2000001200008
Abstract: in the present study the age-related changes of the striated muscle elastic fiber system were investigated in the diaphragm and rectus abdominis muscles of 1-, 4-, 8- and 18-month-old rats. the activation patterns of these muscles differ in that the diaphragm is regularly mobilized tens of times every minute during the entire life of the animal whereas the rectus abdominis, although mobilized in respiration, is much less and more irregularly activated. the elastic fibers were stained by the verhoeff technique for mature elastic fibers. weigert stain was used to stain mature and elaunin elastic fibers, and weigert-oxone to stain mature, elaunin and oxytalan elastic fibers. the density of mature and elaunin elastic fibers showed a progressive increase with age, whereas the amount of oxytalan elastic fibers decreased in both diaphragm and rectus abdominis muscles and their muscular fascias. these age-related quantitative and structural changes of the elastic fiber system may reduce the viscoelastic properties of the diaphragm and rectus abdominis muscles, which may compromise the transmission of tensile muscle strength to the tendons and may affect maximum total strength.
A comparative study of aging of the elastic fiber system of the diaphragm and the rectus abdominis muscles in rats
Rodrigues C.J.,Rodrigues Junior A.J.
Brazilian Journal of Medical and Biological Research , 2000,
Abstract: In the present study the age-related changes of the striated muscle elastic fiber system were investigated in the diaphragm and rectus abdominis muscles of 1-, 4-, 8- and 18-month-old rats. The activation patterns of these muscles differ in that the diaphragm is regularly mobilized tens of times every minute during the entire life of the animal whereas the rectus abdominis, although mobilized in respiration, is much less and more irregularly activated. The elastic fibers were stained by the Verhoeff technique for mature elastic fibers. Weigert stain was used to stain mature and elaunin elastic fibers, and Weigert-oxone to stain mature, elaunin and oxytalan elastic fibers. The density of mature and elaunin elastic fibers showed a progressive increase with age, whereas the amount of oxytalan elastic fibers decreased in both diaphragm and rectus abdominis muscles and their muscular fascias. These age-related quantitative and structural changes of the elastic fiber system may reduce the viscoelastic properties of the diaphragm and rectus abdominis muscles, which may compromise the transmission of tensile muscle strength to the tendons and may affect maximum total strength.
Marinari-Parisi and Supersymmetric Collective Field Theory
J. P. Rodrigues,A. J. van Tonder
Physics , 1992, DOI: 10.1142/S0217751X93001004
Abstract: A field theoretic formulation of the Marinari-Parisi supersymmetric matrix model is established and shown to be equivalent to a recently proposed supersymmetrization of the bosonic collective string field theory. It also corresponds to a continuum description of super-Calogero models. The perturbation theory of the model is developed and, in this approach, an infinite sequence of vertices is generated. A class of potentials is identified for which the spectrum is that of a massless boson and Majorana fermion. For the harmonic oscillator case, the cubic vertices are obtained in an oscillator basis. For a rather general class of potentials it is argued that one cannot generate from Marinari-Parisi models a continuum limit similar to that of the d=1 bosonic string.
Modelling distribution functions and fragmentation functions
J. Rodrigues,A. Henneman,P. J. Mulders
Physics , 1995,
Abstract: We present examples for the calculation of the distribution and fragmentation functions using the representation in terms of non-local matrix elements of quark field operators. As specific examples, we use a simple spectator model to estimate the leading twist quark distribution functions and the fragmentation functions for a quark into a nucleon or a pion.
Influence of the Ratio IA/PA and Volatile Acids in the Monitoring of UASB Reactor in the Treating of Swine Waste Water  [PDF]
Luciano S. Rodrigues, Israel J. Silva, Paulo R. Oliveira, Ana C. A. Pinto, Camila A. Lima
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.65051
Abstract:

This paper presents the influence of the ratio IA/PA and concentration of volatile acids (TVA) in the operational stability of a UASB reactor treating swine waste water. The treatment system in real scale was constituted of decanter, followed by the UASB reactor with volume of 7.4 m3 and 11.5 m3, respectively. It has been observed a large oscillation of the ratio IA/IP in the UASB reactor with an average value of 0.39, and average efficiency of removal of BOD and COD of 79.8 and 79.3%, respectively, at the start, dropping to 0.12 in the continuity of the experiment, including during overload, in which the removal efficiencies of COD and BOD reached values below 10%. The TVA average values were 913 mg·L-1 in the UASB reactor, increasing considerably in the overload period, reaching values higher than 4500 mg·L-1, indicating an accumulation of volatile acids and reduced efficiency of the UASB reactor in removal of organic matter. We conclude that the monitoring of the values of the ratio IA/PA and TVA is very useful instruments and easy to determine in the monitoring of the UASB reactor, enabling to predict possible instabilities in the reactor, allowing corrective actions in a timely manner.

The Min System and Nucleoid Occlusion Are Not Required for Identifying the Division Site in Bacillus subtilis but Ensure Its Efficient Utilization
Christopher D. A. Rodrigues,Elizabeth J. Harry
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1002561
Abstract: Precise temporal and spatial control of cell division is essential for progeny survival. The current general view is that precise positioning of the division site at midcell in rod-shaped bacteria is a result of the combined action of the Min system and nucleoid (chromosome) occlusion. Both systems prevent assembly of the cytokinetic Z ring at inappropriate places in the cell, restricting Z rings to the correct site at midcell. Here we show that in the bacterium Bacillus subtilis Z rings are positioned precisely at midcell in the complete absence of both these systems, revealing the existence of a mechanism independent of Min and nucleoid occlusion that identifies midcell in this organism. We further show that Z ring assembly at midcell is delayed in the absence of Min and Noc proteins, while at the same time FtsZ accumulates at other potential division sites. This suggests that a major role for Min and Noc is to ensure efficient utilization of the midcell division site by preventing Z ring assembly at potential division sites, including the cell poles. Our data lead us to propose a model in which spatial regulation of division in B. subtilis involves identification of the division site at midcell that requires Min and nucleoid occlusion to ensure efficient Z ring assembly there and only there, at the right time in the cell cycle.
ANALYSIS OF THE PREDICTIVE DMC CONTROLLER PERFORMANCE APPLIED TO A FEED-BATCH BIOREACTOR
RODRIGUES, J. A. D.;MACIEL FILHO, R.;
Brazilian Journal of Chemical Engineering , 1997, DOI: 10.1590/S0104-66321997000400009
Abstract: two control algorithms were implemented in the stabilization of the dissolved oxygen concentration of the penicillin process production phase. a deterministic and nonstructured mathematical model was used, where were considered the balances of cell, substrate, dissolved oxygen and product formation as well as kinetic of the growth, respiration, product inhibition due to excess of substrate, penicillin hydrolyze, yield factors among cell growth, substrate consumption and dissolved oxygen consumption. the bioreactor was operated in a feed-batch way using an optimal strategy for the operational policy. the agitation speed was used as manipulated variable in order to achieve the dissolved oxygen control because it was found to be the most sensitive one. two types of control configurations were implemented. first, the pid feedback control with the parameters estimated through modified simplex optimization method using the iae index, and second, the dmc predictive control that had as control parameters the model, prediction and control horizons as well as suppression factor and the trajectory parameter. a sensitivity analysis of these two control algorithms was performed using the sample time and dead time as the index to make stability evaluation. both configurations showed stable performance, however, the predictive one was found to be more robust in relation to the sample time, as well as the dead time variations. this is a very important characteristic to be considered for the implementation of control scheme in real fermentative process
Page 1 /665589
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.