201 resultados para long time behaviour


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O objetivo deste trabalho foi desenvolver protocolo eficiente e reprodutível de imunização em cobaias com antígenos de P. brasiliensis, visando a obtenção de modelo experimental para futuros estudos de mecanismos de proteção imunológica. Testaram-se três diferentes antígenos (particulado, solúvel e composto) e seis protocolos nos quais foram avaliadas as influências dos seguintes fatores: presença ou ausência de adjuvante completo de Freund, número de doses imunizantes e intervalo de tempo entre a última dose imunizante e o desafio. A eficiência do protocolo de imunização foi estudada pela avaliação da resposta imune celular e humoral anti-P. brasiliensis, utilizando teste cutâneo e teste de inibição da migração do macrófago, e imunodifusão, respectivamente. Observou-se que: 1. Três doses imunizantes de antígeno induziram melhor resposta do que duas doses; 2. Maior resposta imune foi conseguida com a utilização de adjuvante completo de Freund; 3. Animais desafiados depois de longo tempo (6 semanas) da última dose imunizante mostraram melhor resposta imune anti-P. brasiliensis; 4. Os antígenos solúvel e composto foram igualmente eficientes induzindo maior resposta imune humoral e celular anti-P. brasiliensis enquanto que o antígeno particulado provocou menor reatividade

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Droplets formed at the tip of a tube under the same conditions possess extreme uniformity of form, volume and weight. These properties of liquid drop formation have been known for a long time and consequently many applications for the drop have been found in instrumentation and chemical analysis methods. In the present paper, we report on the analytical use of a dynamic LED-based flow-through optical absorption detector with optical path length controlled by continuous dropping of a solution. This arrangement consists of a flow cell built within a high-intensity red LED (lambda (max)=630 nm). The feasibility of the detector is demonstrated by colorimetric determination of methylene blue, and ammonium by Berthelot's reaction, in a flow-injection system. For ammonium, the reaction forms a blue dye (indophenol) with a maximum absorption at 630-650 nm. The detection limit, considered as 3 times the signal of the blank, is better than 125 mu g l(-1). The small flow cell represents a good combination of optical path length, low volume and fast washout. This detector can be used advantageously in automated methods and can represent a solution to problems of optical detection involving gas bubbles and precipitation of particles in turbidimetric applications.

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The family Myrtaceae is one of the most important related to fruit species. In Brazil it encloses more than 100 species of native fruit from North to South of the country (Giacometti, 1992; Donadio, 1992; Mattos, 1992). The genus Eugenia, Campomanesia, Psidium and Myrciaria are the most important, grouping most of the species of some importance. The germplasm bank of the Universidade Estadual Paulista includes some of the major species. Some characteristics are typical for most of the Myrtaceae fruit species. The most relevant are the long juvenile period presented by the trees, taking long time to produce, when propagated by seed; the slow growing tree behavior; difficult to propagated by vegetative means; large variability in trees obtained by seed propagation. The cited characteristics are commented for some species as well as the fruit quality, from data obtained in trees at the same ecological conditions.The species evaluated are: 1) Eugenia stipitata Mc Vaugh; 2) Eugenia tomentosa Cambes; 3) Eugenia brasiliensis Lam.; 4) Eugenia uniflora L.; 5) Eugenia luchsnathiana Berg.; 6) Eugenia uvalha Cambess; 7) Camponesia spp; 8) Plinia edulis (Veil. Sobral); 9) Eugenia involucrata D.C.; 10) Psidium acutangulum Mart.; 11) Myrciaria dubia Mc Vaugh; 12) Engenia guabiju Berg. The main conclusions based on the data analysed are: the fruits of some species present good general characteristics, mainly for fresh consumption, as high Vitamin C, sugars, pulp and other characteristics; 'Araca-boi' presents some good fruit characteristics, but is more adapted for processing, by its high acidity; Some species present low % of edible portion and need to be improved to gain commercial acceptance. mainly the 'cabeludinha' and 'cambuca'.

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We report the exact fundamental solution for Kramers equation associated to a Brownian gas of charged particles, under the influence of homogeneous (spatially uniform) otherwise arbitrary, external mechanical, electrical and magnetic fields. Some applications are presented, namely the hydrothermodynamical picture for Brownian motion in the long-time regime. (c) 2005 Elsevier B.V. All rights reserved.

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The running velocities associated to lactate minimum (V-lm), heart rate deflection (V-HRd), critical velocity (CV), 3000 M (V-3000) and 10000 m performance (V-10km) were compared. Additionally the ability of V-lm and VHRd on identifying sustainable velocities was investigated.Methods. Twenty runners (28.5 +/- 5.9 y) performed 1) 3000 m running test for V3000; 2) an all-out 500 in sprint followed by 6x800 m incremental bouts with blood lactate ([lac]) measurements for V-lm; 3) a continuous velocity-incremented test with heart rate measurements at each 200 m for V-HRd; 4) participants attempted to 30 min of endurance test both at V-lm(ETVlm) and V-HRd(ETVHRd). Additionally, the distance-time and velocity-1/time relationships produced CV by 2 (500 m and 3000 m) or 3 predictive trials (500 m, 3000 m and distance reached before exhaustion during ETVHRd), and a 10 km race was recorded for V-10km.Results. The CV identified by different methods did not differ to each other. The results (m(.)min(-1)) revealed that V-.(lm) (281 +/- 14.8)< CV (292.1 +/- 17.5)=V-10km (291.7 +/- 19.3)< V-HRd (300.8 +/- 18.7)=V-3000 (304 +/- 17.5) with high correlation among parameters (P < 0.001). During ETVlm participants completed 30 min of running while on the ETVHRd they lasted only 12.5 +/- 8.2 min with increasing [lac].Conclusion. We evidenced that CV and Vim track-protocols are valid for running evaluation and performance prediction and the parameters studied have different significance. The V-lm reflects the moderate-high intensity domain (below CV), can be sustained without [lac] accumulation and may be used for long-term exercise while the V-HRd overestimates a running intensity that can be sustained for long-time. Additionally, V-3000 and V-HRd reflect the severe intensity domain (above CV).

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The apparent diffusion coefficients for sucrose, NaCl and water during osmotic dehydration of tomatoes in ternary solutions were determined. Long time experiments (up to 60 h) were carried out in order to determine equilibrium concentrations inside tomatoes, whereas short time experiments (up to 4 h) were performed to provide detailed information on kinetics of water loss and solids gain at the beginning of osmotic treatment. The mass transfer rates for water and solutes showed to be dependent of NaCl and sucrose concentrations in osmotic solution and simple regression models as functions of solutes concentration were determined for diffusion coefficients. Salt and sucrose diffusivities showed to be interdependent, with increasing NaCl concentration causing the enhancement of water loss, at the same time that higher sucrose contents hindered the excessive salt penetration. (C) 2003 Elsevier Ltd. All rights reserved.

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We study energy localization on the oscillator chain proposed by Peyrard and Bishop to model DNA. We search numerically for conditions with initial energy in a small subgroup of consecutive oscillators of a finite chain and such that the oscillation amplitude is small outside this subgroup on a long time scale. We use a localization criterion based on the information entropy and verify numerically that such localized excitations exist when the nonlinear dynamics of the subgroup oscillates with a frequency inside the reactive band of the linear chain. We predict a mimium value for the Morse parameter (mu>2.25) (the only parameter of our normalized model), in agreement with the numerical calculations (an estimate for the biological value is mu=6.3). For supercritical masses, we use canonical perturbation theory to expand the frequencies of the subgroup and we calculate an energy threshold in agreement with the numerical calculations.

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Wind-excited vibrations in the frequency range of 10 to 50 Hz due to vortex shedding often cause fatigue failures in the cables of overhead transmission lines. Damping devices, such as the Stockbridge dampers, have been in use for a long time for supressing these vibrations. The dampers are conveniently modelled by means of their driving point impedance, measured in the lab over the frequency range under consideration. The cables can be modelled as strings with additional small bending stiffness. The main problem in modelling the vibrations does however lay in the aerodynamic forces, which usually are approximated by the forces acting on a rigid cylinder in planar flow. In the present paper, the wind forces are represented by stochastic processes with arbitrary crosscorrelation in space; the case of a Kármán vortex street on a rigid cylinder in planar flow is contained as a limit case in this approach. The authors believe that this new view of the problem may yield useful results, particularly also concerning the reliability of the lines and the probability of fatigue damages. © 1987.

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The family Myrtaceae is one of the most important related to fruit species. In Brazil it encloses more than 100 species of native fruit from North to South of the country (Giacometti, 1992; Donadio, 1992; Mattos, 1992). The genus Eugenia, Campomanesia, Psidium and Myrciaria are the most important, grouping most of the species of some importance. The germplasm bank of the Universidade Estadual Paulista includes some of the major species. Some characteristics are typical for most of the Myrtaceae fruit species. The most relevant are the long juvenile period presented by the trees, taking long time to produce, when propagated by seed; the slow growing tree behavior; difficult to propagated by vegetative means; large variability in trees obtained by seed propagation. The cited characteristics are commented for some species as well as the fruit quality, from data obtained in trees at the same ecological conditions. The species evaluated are: 1) Eugenia stipitata Me Vaugh; 2) Eugenia tomentosa Cambes; 3) Eugenia brasiliensis Lam.; 4) Eugenia uniflora L.; 5) Eugenia luchsnathiana Berg.; 6) Eugenia uvalha Cambess; 7) Camponesia spp; 8) Plinia edulis (Veil. Sobral); 9) Eugenia involucrata D.C.; 10) Psidium acutangulum Mart.; 11) Myrciaria dubia Me Vaugh; 12) Eugenia guabiju Berg. The main conclusions based on the data analysed are: The fruits of some species present good general characteristics, mainly for fresh consumption, as high Vitamin C, sugars, pulp and other characteristics; 'Araca-boi' presents some good fruit characteristics, but is more adapted for processing, by its high acidity; Some species present low % of edible portion and need to be improved to gain commercial acceptance, mainly the 'cabeludinha' and 'cambuca'.

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Neonatal high risk children present high incidence for communication disorders and delay development of language. The present study aimed to evaluate the incidence of communication disorders and long term follow up of neonatal high risk children. Twenty-one children were followed up to age of four years old and were evaluated for the development of linguistics aspects. The main high risk neonatal factors were: prematurity, mechanical ventilation, long time in the incubator and severe hypoxia. In 47,62% of the cases, the following communication disorder were found: articulation disorders (9,52%), simple (9,52%) and small and (14,29%) with delay development of language. The incidence of these disorders was greater among male children (57,14%).

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We reinvestigate the dynamics of the grow and collapse of Bose-Einstein condensates in a system of trapped ultracold atoms with negative scattering lengths, and found a new behavior in the long time scale evolution: the number of atoms can go far beyond the static stability limit. The condensed state is described by the solution of the time-dependent nonlinear Schrödinger equation, in a model that includes atomic feeding and three-body dissipation. Our results for the model show that, by changing the feeding parameter and when a substantial depletion of the ground-state exists, a chaotic behavior is found. We consider a criterion proposed by Deissler and Kaneko [Phys. Lett. A 119, 397 (1987)] to diagnose spatiotemporal chaos. ©2000 The American Physical Society.

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The dynamics of small repulsive Bose-Einstein condensed vortex states of 85Rb atoms in a cylindrical traps with low angular momentum was studied. The time-dependent mean-field Gross-Pitaevskii equation was used for the study. The condensates collapsed and atoms ejected via explosion and a remnant condensate with a smaller number of atoms emerges that survived for a long time.

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Some plants are widely distributed, ranging in different vegetation types. Since bird distribution can be directly associated to vegetational cover, we expect that seed dispersers can also vary following phytophysiognomy for some ornithochorous plants. The purpose of this paper was to describe potential seed disperser birds of Talauma ovata (Magnoliaceae) in semideciduous Atlantic forest and cerrado fragments in south-east Brazil. In 79 h of focal observations we recorded 1085 visits of 25 different bird species consuming T. ovata diaspores. Although most bird species observed consuming T. ovata diaspores present generalist habits, they were potential seed dispersers, presenting high visits rate and do not staying a long time on the plants, favoring seed dispersal efficiency. Fruit consumption was not different between species in the study sites and the time spending on the plants was not different between species in semideciduous forest, but was different in cerrado. Agonistic encounters were observed mainly in the end of fruiting season, but was not relevant to decrease the number of seeds dispersed by birds. The occurrence of different potential seed dispersers between areas, such as Cyanocorax cristatellus (Corvidae), Schistochlamys ruficapillus (Emberizidae) and Mimus saturninus (Mimidae), which are endemic from the cerrado ecosystem and could rarely be found in semideciduous forest, suggests that seed dispersers can vary according to phytophysiognomy characteristics. Our results also indicate that the evolution of a generalist seed dispersal system such as observed for T. ovata can make possible the colonization of different ambients. Furthermore, the high number of visits recorded for both areas suggests that the fleshy arils of T. ovata are important feeding resources for birds.

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The structural characteristics of saturated silica sonogels were studied by means of small-angle x-ray scattering (SAXS) and thermogravimetric analysis (TG), after a long time of aging in saturated conditions. The sonogels were obtained by a sol-gel routine from ultrasound stimulated tetramethoxysilane (TMOS) hydrolysis carried out with the initial water/TMOS molar ratio (r) ranging from 2 to 10. The saturated sonogel structure can be described as composed by mass fractal-like aggregates (clusters) of primary silica particles, all imbibed in a liquid phase. The values of the mass fractal dimension (D) of the clusters was found all around 2.5, while the characteristic size of the clusters (ξ) was found generally increasing with r, going from approximately 2.3 nm (r = 2) to 4.5 nm (r = 10). The volume fraction of the clusters was estimated from the SAXS data. The results were compared to the values of weight loss fraction at the inflection point that has been found in the derivative of the TG curve, which should accounts for the instant in which the meniscus of the liquid phase penetrates into the clusters under a rapid evaporation process as in a TG test.

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The existence of a dispersion-managed soliton in two-dimensional nonlinear Schrodinger equation with periodically varying dispersion has been explored. The averaged equations for the soliton width and chirp are obtained which successfully describe the long time evolution of the soliton. The slow dynamics of the soliton around the fixed points for the width and chirp are investigated and the corresponding frequencies are calculated. Analytical predictions are confirmed by direct partial differential equation (PDE) and ordinary differential equation (ODE) simulations. Application to a Bose-Einstein condensate in optical lattice is discussed. The existence of a dispersion-managed matter-wave soliton in such system is shown.