132 resultados para non-uniform scale perturbation finite difference scheme
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It was evaluated the heterogeneity of components of phenotypic variance and its effects on the heritability and repeatability estimates for milk yield in Holstein cattle. The herds were grouped according to their level of production (low, medium and high) and evaluated in the non-transformed, square-root and logarithmic scale. Variance components were estimated using a restricted maximum likelihood method based on an animal model that included fixed effects of herd-year-season, and as covariates the linear effect of lactation duration and the linear and quadratic effects of cow's age at calving and the random direct additive genetic, permanent environment and residual effects. In the non-transformed scale all the variance components were heterogeneous. on this scale, residual and phenotypic variance components were associated positively with the level of production while in logarithmic scale that association was negative. Estimates of heritability were more affected than the repeatability for the phenotypic variance heterogeneity and their components. The of selection process efficiency for milk production could be affected by the level of production which was considered for genetic parameters estimation.
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P>In livestock genetic resource conservation, decision making about conservation priorities is based on the simultaneous analysis of several different criteria that may contribute to long-term sustainable breeding conditions, such as genetic and demographic characteristics, environmental conditions, and role of the breed in the local or regional economy. Here we address methods to integrate different data sets and highlight problems related to interdisciplinary comparisons. Data integration is based on the use of geographic coordinates and Geographic Information Systems (GIS). In addition to technical problems related to projection systems, GIS have to face the challenging issue of the non homogeneous scale of their data sets. We give examples of the successful use of GIS for data integration and examine the risk of obtaining biased results when integrating datasets that have been captured at different scales.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Morphological differences among 6 species of marine fishes belonging to 2 subfamilies of the family Serranidae (Serraninae: Dules auriga, Diplectrum formosum, and D, radiale; Epinephelinae: Epinephelus marginatus, Mycteroperca acutirostris, and M. bonaci) were studied by the geometric morphometric method of thin-plate splines and multivariate analysis of partial-warp scores. The decomposition of shape variation into uniform and nonaffine components of shape change indicate that major differences among species are related to both components of shape variation. Significant differences were found among species with respect to the uniform components, but there is no clear separation of taxonomic groups related to these components, and species are instead separated on the basis of body height and caudal peduncle length. Non-uniform changes in body shape, in turn, clearly differentiate the species of Serraninae and Epinephelinae. These shape changes are probably related to differences in habitat and feeding habits among the species.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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OBJETIVO: Os autores relatam a influência do controle metabólico do diabetes, experimentalmente induzido no rato, sobre a nefropatia diabética. Eles observaram o efeito da insulina, da acarbose, um inibidor da glicosidase, e de dois agentes combinados sobre o controle metabólico e o desenvolvimento da expansão mesangial de glomérulos renais, no diabetes induzido pela aloxana no rato. MÉTODOS: Usando 5 grupos de ratos Wistar assim definidos: Normal(N), diabéticos não-tratados (D), diabéticos tratados com acarbose (AD); diabéticos tratados com insulina (ID) e diabéticos tratados com insulina associada à acarbose (IAD) foram avaliados os seguintes parâmetros: peso corporal, ingestão alimentar, ingestão hídrica, diurese, níveis de glicose sanguínea e urinária e as lesões renais: alargamento mesangial e vacuolização de células tubulares, usando contagem semi-quantitativa 1, 3, 6, 9 e 12 meses após a indução do diabetes. RESULTADOS: Houve acentuado aumento da glicemia, dos níveis de glicose na urina, da diurese, da ingestão hídrica e alimentar, e progressiva perda de peso nos ratos diabéticos, enquanto que os ratos diabéticos tratados exibiram melhora significativa destes parâmetros, sendo os ratos tratados com insulina + acarbose os que apresentaram controle metabólico mais satisfatório. Houve um significativo alargamento mesangial nos ratos diabéticos quando comparado ao observado nos ratos normais, desde o 3º até o 12º mês após a indução do diabetes, sendo observada diferença significativa entre os animais tratados com acarbose + insulina e os ratos diabéticos não-tratados. Não houve diferença significativa entre os animais tratados somente com acarbose ou com insulina quando comparados com ratos diabéticos não-tratados. CONCLUSÃO: Os autores discutem os resultados abordando o papel do controle metabólico do diabetes na prevenção da nefropatia diabética.
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This paper presents the fabrication and analysis of a three-dimensional FCC photonic crystal (PhC) based on a self-assembly synthesis of monodispersive latex spheres. Experimental optical characterization, achieved by measurements of the specular reflectance under variable angles, indicated the clear presence of a Bragg diffraction pattern. Results are further explored by theoretical calculations based on the Finite Difference Time Domain (FDTD) method to determine the full PhC band structure.
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We study a charged Brownian gas with a non uniform bath temperature, and present a thermohydrodynamical picture. Expansion on the collision time probes the validity of the local equilibrium approach and the relevant thermodynamical variables. For the linear regime we present several applications (some novel).
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In rare earth ion doped solids, a resonant non-linear refractive index, n2, appears when the laser pumps one of the ion excited states and the refractive index change is proportional to the excited state population. In these solids there are usually thermal and non-thermal lensing effects, where the non-thermal one is due to the polarizability difference, Δα, between excited and ground states of the ions. We have used the time resolved Z-scan and a mode-mismatched thermal lens technique with an Ar+ ion laser in Er+3 (20ZnF2-20SrF2-2NaF-16BaF2-6GaF3-(36 - x)InF3-xErF3, with x= 1, 2, 3 and 4 mol%) and Nd+3 (20SrF2-16BaF2-20ZnF2-2GdF3-2NaF-(40 - x)InF3-xNdF3, with x = 0.1, 0.25, 0.5-1 mol%) doped fluoroindate glasses. In both samples we found that the non-linear refraction is due to the thermal effect, while the non-thermal effect is negligible. This result indicates that in fluoride glasses Δα is very small (less than 10-26 cm3). We also measured the imaginary part of the non-linear refractive index (n″2) due to absorption saturation.
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An inverse problem concerning the industrial process of steel bars hardening and tempering is considered. The associated optimization problem is formulated in terms of membership functions and, for the sake of comparison, also in terms of quadratic residuals; both geometric and electromagnetic design variables have been considered. The numerical solution is achieved by coupling a finite difference procedure for the calculation of the electromagnetic and thermal fields to a deterministic strategy of minimization based on modified Flctcher and Reeves method. © 1998 IEEE.
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Images and profiles of Vickers impressions produced on as-received float-glass were obtained using atomic force microscopy (AFM). The images show that the impression edges undergo elastic recovery parallel to surface. The profiles made it possible to measure vertical elastic recovery, ev(r). For a 40 g nominal load, maximum penetration depth of indenter was (2.20 ± 0.03) μm, and recovery at the impression center was ev(0) = (0.98 ± 0.03) μm. Vertical elastic recovery was non-uniform along profiles. Permanent impressions produced resulted from glass mass displacement downward, producing an increase in glass density in impression vicinity, which is discussed in terms of changes in O-Si-O and Si-O-Si bond angles and Si-O bond length. Near impression edges, pileup was observed for which a simplified model is proposed taking into account the compaction and stresses near the impressions. © 2000 Elsevier Science B.V. All rights reserved.
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The transient process of solidification of laminar liquid flow (water) submitted to super-cooling was investigated both theoretically and experimentally. In this study an alternative analytical formulation and numerical approach were adopted resulting in the unsteady model with temperature dependent thermophysical properties in the solid region. The proposed model is based upon the fundamental equations of energy balance in the solid and liquid regions as well as across the solidification front. The basic equations and the associated boundary and initial conditions were made dimensionless by using the Landau transformation to immobilize the moving front and render the problem to a fixed plane type problem. A laminar velocity profile is admitted in the liquid domain and the resulting equations were discretized using the finite difference approach. The numerical predictions obtained were compared with the available results based on other models and concepts such as Neumann analytical model, the apparent thermal capacity model due to Bonacina and the conventional fixed grid energy model due to Goodrich. To obtain further comparisons and more validation of the model and the numerical solution, an experimental rig was constructed and instrumented permitting very well controlled experimental measurements. The numerical predictions were compared with the experimental results and the agreement was found satisfactory.
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The pulsed electric acoustic technique, PEA, have been usually applied to probe space charge profiles in polymers. In this work we show preliminary results obtained with lead zirconate-titanate and niobium, PZTN, ferroelectric ceramic samples. Experiments showed that induced charge densities on sample electrodes are mainly due to the ferroelectric polarization of the sample. We present results of the typical PEA response and the procedure to deconvolute the signal in order to obtain the charge densities and the electric field profiles. The PEA setup allows us to show a non-uniform polarization during ferroelectric switching.
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The biggest advantage of plasma immersion ion implantation (PIII) is the capability of treating objects with irregular geometry without complex manipulation of the target holder. The effectiveness of this approach relies on the uniformity of the incident ion dose. Unfortunately, perfect dose uniformity is usually difficult to achieve when treating samples of complex shape. The problems arise from the non-uniform plasma density and expansion of plasma sheath. A particle-in-cell computer simulation is used to study the time-dependent evolution of the plasma sheath surrounding two-dimensional objects during process of plasma immersion ion implantation. Before starting the implantation phase, steady-state nitrogen plasma is established inside the simulation volume by using ionization of gas precursor with primary electrons. The plasma self-consistently evolves to a non-uniform density distribution, which is used as initial density distribution for the implantation phase. As a result, we can obtain a more realistic description of the plasma sheath expansion and dynamics. Ion current density on the target, average impact energy, and trajectories of the implanted ions were calculated for three geometrical shapes. Large deviations from the uniform dose distribution have been observed for targets with irregular shapes. In addition, effect of secondary electron emission has been included in our simulation and no qualitative modifications to the sheath dynamics have been noticed. However, the energetic secondary electrons change drastically the plasma net balance and also pose significant X-ray hazard. Finally, an axial magnetic field has been added to the calculations and the possibility for magnetic insulation of secondary electrons has been proven.