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Search Results: 1 - 10 of 638129 matches for " F. T. A dos Santos "
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Detec??o de Heterodera glycines em plantio de soja mediante espectrorradiometria no visível e infravermelho próximo
Fitopatologia Brasileira , 2002, DOI: 10.1590/S0100-41582002000400004
Abstract: the damage caused by the soybean cyst nematode, heterodera glycines, not only limits expansion of the soybean (glycine max) crop but also reduces the yield of soybeans in brazil. knowledge of the spatial distribution of this pathogen is needed in order to establish management measures. this study was conducted in florínea county, s?o paulo, brazil, in a commercial soybean field, cultivar brs133, previously known to be infected with h. glycines. in order to see the pattern of the spectral response of plants attacked by the phytonematode, field spectroradiometry measurements in the visible and near infrared regions of the electromagnetic spectrum were obtained 112 days after sowing. at the same time, soil samples were taken to the "laboratório de nematologia do departamento de fitossanidade da universidade estadual paulista júlio de mesquita filho, campus de jaboticabal", where they were processed and where the population density of the nematode was determined. the spectroradiometric measurements were transformed to the normalized difference vegetation index (ndvi) that was related to population density of the nematode, to fresh biomass and to pods per plant. it was observed that different population densities are directly related to the spectral response of the plants expressed by ndvi values.
Detec o de Heterodera glycines em plantio de soja mediante espectrorradiometria no visível e infravermelho próximo
Fitopatologia Brasileira , 2002,
Abstract: O ataque do nematóide de cisto da soja, Heterodera glycines, limita o potencial de expans o e maior produtividade de áreas plantadas com soja (Glycine Max). O conhecimento da distribui o espacial desse patógeno na lavoura é fundamental, para elabora o de estratégias de manejo. A área em estudo estava localizada em lavoura de soja, variedade BRS133, localizada no Município de Florínea, SP, com solos naturalmente infestados por H. glycines. Foram obtidas medidas de espectrorradiometria de campo, 112 dias após o plantio, nas regi es do visível e do infravermelho próximo do espectro eletromagnético, a fim de se conhecer o padr o da resposta espectral de plantas atacadas pelo fitonematóide. Paralelamente, foram retiradas amostras de solo e encaminhadas ao Laboratório de Nematologia, Departamento de Fitossanidade da Universidade Estadual Paulista Júlio de Mesquita Filho, Campus de Jaboticabal, onde foram processadas para determina o da densidade populacional do nematóide. As medidas do espectrorradi metro foram transformadas em índice vegetativo, com diferen a normalizada (NDVI), que foi relacionado com a densidade populacional do nematóide, peso da matéria fresca e número de vagens por planta. Observou-se que diferentes densidades de popula o est o diretamente relacionados com a resposta espectral das plantas expressa, através dos valores do NDVI.
Evaluation of subsurface contact stresses in railroad wheels using an elastic half-space model
Santos, F. de C.;Santos Jr, A. A. dos;Bruni, F.;Santos, L. T.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2004, DOI: 10.1590/S1678-58782004000400007
Abstract: railroad wheels fail in two main modes: rolling surface defects like spalling, shelling and wear, and internal defects including cracks propagating after a change takes place in the original stress pattern. although the effects of the latter are almost always catastrophic, the former is more usual. the onset of rolling surface defects depends on the strength of the surface and the applied loads. the strength is related to surface hardness and can be determined through experimental evaluation under controlled conditions. evaluating the loads is one of the challenges for contact researchers. this paper presents the evaluation of the stress field inside elastic rolling bodies with an elliptic area of contact. this kind of model can be applied to wheel-rail contact phenomena. typical high freight transportation loads are used in conjunction with regular recommended wheel and rail sizes. the results have shown that shear stress reaches the maximum magnitude below the surface of contact, and this explains the presence of shelling defects in service. they have also shown that a new model including plasticity is required, because the range of the stresses reached surpasses, by far, the elastic limit
Real-Time Ginzburg-Landau Theory for Bosons in Optical Lattices
T. D. Grass,F. E. A. dos Santos,A. Pelster
Physics , 2010, DOI: 10.1134/S1054660X11150096
Abstract: Within the Schwinger-Keldysh formalism we derive a Ginzburg-Landau theory for the Bose-Hubbard model which describes the real-time dynamics of the complex order parameter field. Analyzing the excitations in the vicinity of the quantum phase transitions it turns out that particle/hole dispersions in the Mott phase map continuously onto corresponding amplitude/phase excitations in the superfluid phase. Furthermore, in the superfluid phase we find a sound mode, which is in accordance with recent Bragg spectroscopy measurements in the Bogoliubov regime, as well as an additional gapped mode, which seems to have been detected via lattice modulation.
Excitation Spectra of Bosons in Optical Lattices from Schwinger-Keldysh Calculation
T. D. Grass,F. E. A. dos Santos,A. Pelster
Physics , 2010, DOI: 10.1103/PhysRevA.84.013613
Abstract: Within the Schwinger-Keldysh formalism we derive a Ginzburg-Landau theory for the Bose-Hubbard model which describes the real-time dynamics of the complex order parameter field. Analyzing the excitations in the vicinity of the quantum phase transition it turns out that particle/hole dispersions in the Mott phase map continuously onto corresponding amplitude/phase excitations in the superfluid phase, which have been detected recently by Bragg spectroscopy measurements.
Anxiolytic-like and sedative effects of Hydrocotyle umbellata L., Araliaceae, extract in mice
Fábio F. Rocha,Cláudio S. Almeida,Rafael T. dos Santos,Suely A. Santana
Revista Brasileira de Farmacognosia , 2011,
Abstract: The plant Hydrocotyle umbellata L., Araliaceae (water pennywort), is widely used in Brazilian folk medicine to reduce anxiety. This work investigates the anxiolytic-like effects of the ethanol extract from H. umbellata subterraneous parts as well as the extract's other putative central nervous system effects that could justify its common use. Oral dosing of the extract (0.3 and 1 g/kg) clearly showed an anxiolytic-like profile in the elevated plus maze test where it increased the percentage of entries into and the time spent in the open arms of the maze. In the marble-burying test, the extract induced anxiolytic-like effects only at a dose of 1 g/kg, which also causes mild sedative properties in other models. The sedated state was characterized by a slight reduction in spontaneous exploratory activity during the open field test and a potentiating of pentobarbital-induced hypnosis. No signs of motor impairment were detected in the rota rod or chimney tests. The extract did not show antidepressant properties in mice as assessed by the forced swimming test. These results support the use of H. umbellata in Brazilian folk medicine as an anxiolytic and contribute to the scientific knowledge of this possible phytotherapeutic resource.
Identification of material properties using full-field and non contact measurements
Nunes, Luiz C. S.;Castello, Daniel A.;Santos, Paulo A. M. dos;Matt, Carlos F. T.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2009, DOI: 10.1590/S1678-58782009000300001
Abstract: in the present work, the digital image correlation (dic) measurement method is used to obtain the displacement field of specific regions of a cantilever beam under bending. these fields are used within an inverse analysis scheme in order to obtain the elasticity modulus of the beam material. the parameter estimation is performed by means of the minimization of an error function comprising of the difference between the displacement fields obtained from the experiment and from an appropriate mathematical model. the inverse problem is solved by means of the classical levenberg-marquardt nonlinear parameter estimation technique. the estimate obtained for the elasticity modulus is validated taking into account new experimental data obtained through modal analysis of another beam-like specimen which, in turn, is made of the same material as the original one.
Transportable laser system for atom interferometry
P. Cheinet,F. Pereira Dos Santos,T. Petelski,J. Le Gou?t,K. T. Therkildsen,A. Clairon,A. Landragin
Physics , 2005, DOI: 10.1007/s00340-006-2266-2
Abstract: We describe an optical bench in which we lock the relative frequencies or phases of a set of three lasers in order to use them in a cold atoms interferometry experiment. As a new feature, the same two lasers serve alternately to cool atoms and to realize the atomic interferometer. This requires a fast change of the optical frequencies over a few GHz. The number of required independent laser sources is then only 3, which enables the construction of the whole laser system on a single transportable optical bench. Recent results obtained with this optical setup are also presented.
A study of nanocrystalline cobalt prepared by ball milling
J. C. de Lima,V. H. F. dos Santos,T. A. Grandi,R. S. de Biasi
Physics , 2000,
Abstract: The hcp-fcc transformation induced in cobalt powder by ball milling at room temperature was studied using the excess Gibbs free energy for the metals, in nanometric form, to calculate the activation energy that the atoms need for the phase transformation to occur. The crystalline component of the nanocrystalline cobalt produced in our laboratory, via ball milling, was analized using the radial distribution function technique. The results suggest that the crystalline component has the same structure as the bulk, contradicting results already reported.
Importancia de la Relación Anatómica entre el nervio Isquiático y el Margen Posterior del Acetábulo en la Luxación Posterior de la Cadera Anatomic Value of the Sciatic Nerve with the Posterior Margin of the Acetabulum in Posterior Dislocation of the Hip
A. C da Rocha,R. F Monte Bispo,R. D da Cruz,F. T. A dos Santos
International Journal of Morphology , 2012,
Abstract: La luxación posterior de la articulación de la cadera es un trauma que puede sufrir una buena parte de la población, donde se puede comprometer el nervio isquiático, produciendo serios problemas en la vida del individuo afectado. El conocimiento de la relación anatómica entre el nervio isquiático y el margen posterior del acetábulo propiciará um diagnóstico preciso y precoz de esta lesión. Con el objetivo de estudiar la relación topográfica del nervio isquiático con el margen posterior del acetábulo y entregar antecedentes anatómicos para las cirugías ortopédicas en caso de luxaciones posteriores de la cadera, se estudiaron 40 miembros inferiores formolizados, de cadáveres humanos, adultos y de ambos sexos, localizados en los laboratorios de anatomía topográfica de la Universidad Estadual de Ciencias de la Salud de Alagoas, Brasil. En 19 miembros inferiores (47,7%) el nervio isquiático pasó directamente sobre el margen posterior del acetábulo y en los 21 restantes (53,3%), el nervio estuvo distante del margen mencionado, distancia que varió de 6 a 49 mm. Los resultados obtenidos muestran la estrecha relación entre el nervio isquiático y el margen acetabular, lo que acrecienta la posibilidad de lesión del nervio em los casos de luxación posterior de la cadera. The posterior dislocation of the hip joint is a trauma that can undergo a large part of the population, which may compromise the sciatic nerve, causing serious problems in the life of the affected individual. Knowledge of the anatomical relationship between the sciatic nerve and the posterior margin of the acetabulum will facilitate accurate diagnosis and early um this injury. In order to study the topographical relationship of the sciatic nerve with the posterior margin of the acetabulum and provide background for orthopedic anatomical in posterior dislocations of the hip were studied 40 lower limbs formolized human cadavers, adults of both sexes , located in the topographical anatomy laboratories of the Universidade Estadual de Ciencias da Saude, Alagoas, Brasil. In 19 limbs (47.7%) sciatic nerve passed directly over the posterior margin of the acetabulum and the remaining 21 (53.3%), the nerve passed distal to the acetabular margin, distance ranging from 6-49 mm. The results show the close relationship between the sciatic nerve and the acetabular margin, which increases the possibility of nerve injury in posterior dislocation of the hip.
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