942 resultados para Fold and flip bifurcation curves


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A brief overview of optical monitoring for vacuum and wet bench film deposition processes is presented. Interferometric and polarimetric measurements are combined with regard to simultaneous real-time monitoring of refractive index and physical thickness. Monitor stability and accuracy are verified with transparent oil standards. This double optical technique is applied to dip coating with a multi-component Zirconyl Chloride aqueous solution, whose time varying refractive index and physical thickness curves indicate significant sensitivity to changes of film flow properties during the process.

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The formation of sulfated zirconia films from a sol-gel derived aqueous suspension is subjected to double-optical monitoring during batch dip coating. Interpretation of interferometric patterns, previously obscured by a variable refractive index, is now made possible by addition of its direct measurement by a polarimetric technique in real time. Significant sensitivity of the resulting physical thickness and refractive index curves (uncertainties of ±7 nm and ±0.005, respectively) to temporal film evolution is shown under different withdrawal speeds. As a first contribution to quantitative understanding of temporal film formation with varying nanostructure during dip coating, detailed analysis is directed to the stage of the process dominated by mass drainage, whose simple modeling with temporal t-1/2 dependence is verified experimentally. © 2006 Elsevier B.V. All rights reserved.

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The aim of this work was to evaluate the effect of physical preconditioning in the responsiveness of rat pulmonary rings submitted to lung ischemia/reperfusion (IR). Wistar rats were divided into three groups: Sedentary sham-operated (SD/SHAM); sedentary submitted to ischemia/reperfusion (SD/IR) and trained submitted to ischemia/reperfusion (TR/IR) animals. Exercise training consisted in sessions of 60 min/day running sessions, 5 days/week for 8 weeks. Left pulmonary IR was performed by occluding for 90 min and reperfusing for 120 min. After that, pulmonary arteries were isolated and concentration-response curves to acetylcholine (ACh), histamine (HIST), sodium nitroprusside (SNP), phenylephrine and U46619 were obtained. Neither potency (- log EC50) nor maximal responses (Emax) were modified for ACh and HIST in all groups. On the other hand, the potency for SNP was significantly increased in TR/IR group (8.23 ± 0.06) compared to SD/IR group (7.85 ± 0.04). Contractile responses mediated by a-adrenergic receptor were markedly decreased in IR groups (SD/IR: 6.75 ± 0.06 and TR/IR: 6.62 ± 0.04) compared to SD/SHAM (7.33 ± 0.05). No changes were seen for the U46619 in all groups. In conclusion, the present study shows that exercise training has no protective actions in the local blood vessel where the IR process takes place. © 2006 Elsevier Inc. All rights reserved.

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Objectives: To examine the effects of triiodothyronine (T3), 17β-estradiol (E2), and tamoxifen (TAM) on transforming growth factor (TGF)-α gene expression in primary breast cancer cell cultures and interactions between the different treatments. Methods and results: Patients included in the study (no.=12) had been newly diagnosed with breast cancer. Fresh human breast carcinoma tissue was cut into 0.3-mm slices. These slices were placed in six 35-mm dishes on 2-ml organ culture medium. Dishes received the following treatments: dish 1: ethanol; dish 2: T3; dish 3: T3+TAM; dish 4: TAM; dish 5: E2; dish 6: E2+TAM. TGF-α mRNA content was normalized to glyceraldehyde-3-phosphate dehydrogenase mRNA levels. All tissues included in this study were positive for estrogen receptor (ER) and thyroid hormone receptor expression. Treatment with T3 for 48 h significantly increased TGF-α mRNA levels compared to controls (15-fold), and concomitant treatment with TAM reduced expression to 3.4-fold compared to controls. When only TAM was added to the culture medium, TGF-α mRNA expression increased 5.3-fold, significantly higher than with all other treatment modalities. Conclusion: We demonstrate that TGF-α mRNA expression is more efficiently upregulated by T3 than E2. Concomitant treatment with TAM had a mitigating effect on the T3 effect, while E2 induced TGF-α upregulation. Our findings show some similarities between primary culture and breast cancer cell lines, but also some important differences: a) induction of TGF-α, a mitogenic protein, by TAM; b) a differential effect of TAM that may depend on relative expression of ER α and β; and c) supraphysiological doses of T3 may induce mitogenic signals in breast cancer tissue under conditions of low circulating E2. ©2008, Editrice Kurtis.

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In this work it is proposed an optimized dynamic response of parallel operation of two single-phase inverters with no control communication. The optimization aims the tuning of the slopes of P-ω and Q-V curves so that the system is stable, damped and minimum settling time. The slopes are tuned using an algorithm based on evolutionary theory. Simulation and experimental results are presented to prove the feasibility of the proposed approach. © 2010 IEEE.

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This work aimed at describing the Neoproterozoic evolution of a Southern Brasília Fold Belt segment, in Tapira area (southwest of Minas Gerais state, Brazil), using detailed geologic mapping. This area, the Canastra Group type-area, has showed great tectonic and stratigraphic complexities unlike the simplicity suggested in previous works. From recognizing the main tectonic discontinuities, it was possible to subdivide the area into some domains. In the west domain, they were individualized in tectonic sheet I, marked by pelitic rocks and pelitic-graphite rocks with psammitic intercalations, and II, pelitic rocks with psammitic and mafic-ultramafic intercalations overlapped by gneisses. In the east domain, a group of three tectonic sheets was defined, in which, in the two lower tectonic sheets, pelitic and pelitic-graphite rocks with psammitic rock intercalations prevailed, which is different in metamorphic conditions. The lower tectonic sheet is marked by mineralogical associations with muscovite + chlorite + quartz ± graphite ± albite, without biotite; however, the superior one is with muscovite + quartz + garnet ± chlorite ± biotite ± chloritoid ± graphite ± albite. In the upper tectonic sheet, pelitic rocks with local contributions of psammitic and ultramafics rocks occur. In the south domain, psammitic rocks basically occur with contributions of pelitics and rudaceous rocks, where the preservation of textures and sedimentary structures is common. Rocks of the several domains are interpreted as part of a passive continental margin basin, located in the western margin of the São Francisco paleocontinent. Thus, the south domain rocks would represent the facies of proximal platform; rocks of the lower and middle tectonic sheets (east domain) and of the tectonic sheet I (west domain) are of facies distal platform; and the ones from the upper tectonic sheet (east domain) and tectonic sheet II (west domain) were acknowledged as deposited in an environment of continental shelf and/or oceanic seafoor.

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We consider dynamical properties for an ensemble of classical particles confined to an infinite box of potential and containing a time-dependent potential well described by different nonlinear functions. For smooth functions, the phase space contains chaotic trajectories, periodic islands and invariant spanning curves preventing the unlimited particle diffusion along the energy axis. Average properties of the chaotic sea are characterised as a function of the control parameters and exponents describing their behaviour show no dependence on the perturbation functions. Given invariant spanning curves are present in the phase space, a sticky region was observed and show to modify locally the diffusion of the particles. © 2013 Elsevier B.V.

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Includes bibliography

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)