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Search Results: 1 - 10 of 603721 matches for " R. A.;Medeiros "
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Meiofauna de praia arenosa da Ilha Anchieta, S?o Paulo: I. fatores físicos
Medeiros, Liliana R. A.;
Boletim do Instituto Oceanográfico , 1992, DOI: 10.1590/S0373-55241992000100003
Abstract: as part of a meiofaunistic research, this paper describes some relevant physical factors of a moderately exposed sandy beach located at anchieta island (23o32's - 45o04'w), brazil. reflective and dissipative domains could be recognized. these domains differ by the hydrodynamic forces to which they are submitted, grain size and sorting characteristics, pore space available to interstitial life, temperature, water and organic contents, relative stability, isolation from the adjacent marine system, and historical aspects.
Meiofauna de praia arenosa da Ilha Anchieta, S?o Paulo: I. Fatores físicos
Medeiros, Liliana R. A;
Brazilian Journal of Oceanography , 1992, DOI: 10.1590/S1679-87591992000100003
Abstract: as part of a meiofaunistic research, this paper describes some relevant physical factors of a moderately exposed sandy beach located at anchieta island (23o32's - 45o04'w), brazil. reflective and dissipative domains could be recognized. these domains differ by the hydrodynamic forces to which they are submitted, grain size and sorting characteristics, pore space available to interstitial life, temperature, water and organic contents, relative stability, isolation from the adjacent marine system, and historical aspects.
Evidence for rotation-induced mixing in evolved intermediate mass stars
R. Smiljanic,B. Barbuy,J. R. De Medeiros,A. Maeder
Revista mexicana de astronomía y astrofísica , 2006,
Abstract: Muchos resultados observacionales parecen indicar procesos de mezclado m as e cientes en estrellas de masas intermedias (5-20 M ) que los esperados de los m etodos est andar. Por lo general se piensa que estos procesos son producidos por la rotaci on estelar. De nuestro an alisis reciente de 19 estrellas de masas intermedias evolucionadas se ha encontrado que estas presentan diferentes e ciencias de mezclado interno. La comparaci on de estos resultados y de otros de la bibliograf a , con modelos evolutivos estelares rotacionales y no rotacionales nos ha permitido encontrar, por vez primera, una importante correlaci on entre masa estelar y [N/C]; es decir, la clase de correlaci on que se espera sea producida por mezclado inducido por rotaci on.
Nonabelian topological mass mechanism for a three-dimensional 2-form field
D. M. Medeiros,R. R. Landim,C. A. S. Almeida
Physics , 2000,
Abstract: Starting from a recently proposed abelian topological model in (2+1) dimensions, we use the method of the consistent deformations to prove that a topologically massive model involving the Kalb-Ramond two form field does not admit a nonabelian generalization. The introduction of a connection-type one form field keeps the previous result. However we show that the goal is achieved if we introduce a vectorial auxiliary field, exhibiting a nonabelian topological mass generation mechanism in D=3, that provides mass for the Kalb-Ramond field. Further, we find the complete set of BRST and anti-BRST equations using the horizontality condition, suggesting a connection between this formalism and the method of the consistent deformations.
Mass generation for non-Abelian antisymmetric tensor fields in a three-dimensional space-time
D. M. Medeiros,R. R. Landim,C. A. S. Almeida
Physics , 2001, DOI: 10.1103/PhysRevD.63.127702
Abstract: Starting from a recently proposed Abelian topological model in (2+1) dimensions, which involve the Kalb-Ramond two form field, we study a non-Abelian generalization of the model. An obstruction for generalization is detected. However we show that the goal is achieved if we introduce a vectorial auxiliary field. Consequently, a model is proposed, exhibiting a non-Abelian topological mass generation mechanism in D=3, that provides mass for the Kalb-Ramond field. The covariant quantization of this model requires ghosts for ghosts. Therefore in order to quantize the theory we construct a complete set of BRST and anti-BRST equations using the horizontality condition.
Non-Chern-Simons Topological Mass Generation in (2+1) Dimensions
Deusdedit M. Medeiros,R. R. Landim,C. A. S. Almeida
Physics , 1999, DOI: 10.1209/epl/i1999-00527-x
Abstract: By dimensional reduction of a massive BF theory, a new topological field theory is constructed in (2+1) dimensions. Two different topological terms, one involving a scalar and a Kalb-Ramond fields and another one equivalent to the four-dimensional BF term, are present. We constructed two actions with these topological terms and show that a topological mass generation mechanism can be implemented. Using the non-Chern-Simons topological term, an action is proposed leading to a classical duality relation between Klein-Gordon and Maxwell actions. We also have shown that an action in (2+1) dimensions with the Kalb-Ramond field is related by Buscher's duality transformation to a massive gauge-invariant Stuckelberg-type theory.
Consistent deformations method applied to a topological coupling of antisymmetric gauge fields in D=3
D. M. Medeiros,R. R. Landim,C. A. S. Almeida
Physics , 2001, DOI: 10.1016/S0370-2693(01)00182-4
Abstract: In this work we use the method of consistent deformations of the master equation by Barnich and Henneaux in order to prove that an abelian topological coupling between a zero and a two form fields in D=3 has no nonabelian generalization. We conclude that a topologically massive model involving the Kalb-Ramond two-form field does not admit a nonabelian generalization. The introduction of a connection-type one form field keeps the previous result.
Remarks on nonlinear biharmonic evolution equation of Kirchhoff type in noncylindrical domain
J. Límaco,H. R. Clark,L. A. Medeiros
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s0161171203206347
Abstract: We investigate a boundary value problem for a nonlinear evolution biharmonic operator motivated by flexion of fully clamped beam in two different physical situations. In the first, the supports of the ends of the beam are fixed and in the second one, the supports of the ends of the beam have small displacements.
Effect of plant diversification on abundance of South American tomato pinworm and predators in two cropping systems
Medeiros, Maria A;Sujii, Edison R;Morais, Helena C;
Horticultura Brasileira , 2009, DOI: 10.1590/S0102-05362009000300007
Abstract: several studies have demonstrated that the diversification of the agroecosystem may reduce insect pest infestation using the strategy of companion planting. we studied the effect of the presence of coriander and gallant soldier as companion plants in the tomato crop under organic and conventional management on abundance of the tomato pests and predators. the experiment was carried out under field conditions, at distrito federal, brazil, from july to october, 2004. the experimental design was of randomized blocks with three replicates in a 3 x 2 factorial arrangement [three crop diversification levels: tomato in monoculture, tomato intercropped with coriander, and tomato intercropped with coriander and gallant soldier; and two cropping systems: organic and conventional]. each plot had 80 plants of the tomato and the pest-insects and predaceous arthropods were collected every week in five tomato plants/plot. tuta absoluta (meyr.) was the commonest pest species in both cropping systems. the tomato intercropped with coriander and gallant soldier in organic cropping system had lower abundance and higher diversity of pests, and higher abundance and diversity of predaceous arthropods, mainly at 80 days after the tomato transplanting, coinciding with the population peak of t. absoluta (eggs and adults). the more abundant predators were spiders, lady beetles and ants. the spiders were abundant and uniformly distributed in both systems. the lady beetles appeared lately in the organic system, at the flowering season of the coriander. the ants were more abundant in the conventional systems.
Investigation of single-strand conformational polymorphism of the TP53 gene in women with a family history of breast cancer
Burbano R.R.,Medeiros A.C.,Mello A.A.,Lemos J.A.
Brazilian Journal of Medical and Biological Research , 2000,
Abstract: Breast cancer in families with germ line mutations in the TP53 gene has been described in the medical literature. Mutation screening for susceptibility genes should allow effective prophylactic and preventive measures. Using single-strand conformational polymorphism, we screened for mutations in exons 5, 6, 7 and 8 of gene TP53 in the peripheral blood of 8 young non-affected members (17 to 36 years old) of families with a history of breast cancer. Studies of this type on young patients (mean age, 25 years) are very rare in the literature. The identification of these mutations would contribute to genetic counseling of members of families with predisposition to breast cancer. The results obtained did not show any polymorphism indicating mutation. In our sample, the familial tumorigenesis is probably related to other gene etiologies.
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