11 resultados para Path formulation

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)


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This work describes the tropical town energy budget (t-TEB) scheme addressed to simulate the diurnal occurrence of the urban heat island (UHI) as observed in the Metropolitan Area of Rio de Janeiro (MARJ; -22A degrees S; -44A degrees W) in Brazil. Reasoning about the tropical urban climate have guided the scheme implementation, starting from the original equations from Masson (Bound-Lay Meteorol 94:357-397, 2000). The modifications include (a) local scaling approaches for obtaining flux-gradient relationships in the roughness sub-layer, (b) the Monin-Obukhov similarity framework in the inertial sub-layer, (c) increasing aerodynamic conductance toward more unstable conditions, and (d) a modified urban subsurface drainage system to transfer the intercepted rainwater by roofs to the roads. Simulations along 2007 for the MARJ are obtained and compared with the climatology. The t-TEB simulation is consistent with the observations, suggesting that the timing and dynamics of the UHI in tropical cities could vary significantly from the familiar patterns observed in mid-latitude cities-with the peak heat island intensity occurring in the morning than at night. The simulations are suggesting that the thermal phase shift of this tropical diurnal UHI is a response of the surface energy budget to the large amount of solar radiation, intense evapotranspiration, and thermal response of the vegetated surfaces over a very humid soil layer.

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Paleomagnetic and rockmagnetic data are reported for the Floresta Formation (Santa Fe Group) of the Sanfranciscana Basin, central Brazil. This formation represents the Permo-Carboniferous glacial record of the basin and comprises the Brocoto (diamictites and flow diamictites), Brejo do Arroz (red sandstones and shales with dropstones and invertebrate trails), and Lavado (red sandstones) members, which crop out near the cities of Santa Fe de Minas and Canabrava, Minas Gerais State. Both Brejo do Arroz and Lavado members were sampled in the vicinities of the two localities. Alternating field and thermal demagnetizations of 268 samples from 76 sites revealed reversed components of magnetization in all samples in accordance with the Permo-Carboniferous Reversed Superchron. The magnetic carriers are magnetite and hematite with both minerals exhibiting the same magnetization component, suggesting a primary origin for the remanence. We use the high-quality paleomagnetic pole for the Santa Fe Group (330.9 degrees E 65.7 degrees S; N = 60; alpha(95) = 4.1 degrees; k = 21) in a revised late Carboniferous to early Triassic apparent polar wander path for South America. On the basis of this result it is shown that an early Permian Pangea A-type fit is possible if better determined paleomagnetic poles become available.

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This paper addresses the independent multi-plant, multi-period, and multi-item capacitated lot sizing problem where transfers between the plants are allowed. This is an NP-hard combinatorial optimization problem and few solution methods have been proposed to solve it. We develop a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic as well as a path-relinking intensification procedure to find cost-effective solutions for this problem. In addition, the proposed heuristics is used to solve some instances of the capacitated lot sizing problem with parallel machines. The results of the computational tests show that the proposed heuristics outperform other heuristics previously described in the literature. The results are confirmed by statistical tests. (C) 2009 Elsevier B.V. All rights reserved.

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We propose an alternative formulation of the Standard Model which reduces the number of free parameters. In our framework, fermionic fields are assigned to fundamental representations of the Lorentz and the internal symmetry groups, whereas bosonic field variables transform as direct products of fundamental representations of all symmetry groups. This allows us to reduce the number of fundamental symmetries. We formulate the Standard Model by considering the SU(3) and SU(2) symmetry groups as the underlying symmetries of the fundamental interactions. This allows us to suggest a model, for the description of the interactions of the intermediate bosons among themselves and interactions of fermions, that makes use of just two parameters. One parameter characterizes the symmetric phase, whereas the other parameter (the asymmetry parameter) gives the breakdown strength of the symmetries. All coupling strengths of the Standard Model are then derived in terms of these two parameters. In particular, we show that all fermionic electric charges result from symmetry breakdown.

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The third law of thermodynamics is formulated precisely: all points of the state space of zero temperature I""(0) are physically adiabatically inaccessible from the state space of a simple system. In addition to implying the unattainability of absolute zero in finite time (or ""by a finite number of operations""), it admits as corollary, under a continuity assumption, that all points of I""(0) are adiabatically equivalent. We argue that the third law is universally valid for all macroscopic systems which obey the laws of quantum mechanics and/or quantum field theory. We also briefly discuss why a precise formulation of the third law for black holes remains an open problem.

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Path-integral representations for a scalar particle propagator in non-Abelian external backgrounds are derived. To this aim, we generalize the procedure proposed by Gitman and Schvartsman of path-integral construction to any representation of SU(N) given in terms of antisymmetric generators. And for arbitrary representations of SU(N), we present an alternative construction by means of fermionic coherent states. From the path-integral representations we derive pseudoclassical actions for a scalar particle placed in non-Abelian backgrounds. These actions are classically analyzed and then quantized to prove their consistency.

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It is known that the actions of field theories on a noncommutative space-time can be written as some modified (we call them theta-modified) classical actions already on the commutative space-time (introducing a star product). Then the quantization of such modified actions reproduces both space-time noncommutativity and the usual quantum mechanical features of the corresponding field theory. In the present article, we discuss the problem of constructing theta-modified actions for relativistic QM. We construct such actions for relativistic spinless and spinning particles. The key idea is to extract theta-modified actions of the relativistic particles from path-integral representations of the corresponding noncommutative field theory propagators. We consider the Klein-Gordon and Dirac equations for the causal propagators in such theories. Then we construct for the propagators path-integral representations. Effective actions in such representations we treat as theta-modified actions of the relativistic particles. To confirm the interpretation, we canonically quantize these actions. Thus, we obtain the Klein-Gordon and Dirac equations in the noncommutative field theories. The theta-modified action of the relativistic spinning particle is just a generalization of the Berezin-Marinov pseudoclassical action for the noncommutative case.

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The topology of real-world complex networks, such as in transportation and communication, is always changing with time. Such changes can arise not only as a natural consequence of their growth, but also due to major modi. cations in their intrinsic organization. For instance, the network of transportation routes between cities and towns ( hence locations) of a given country undergo a major change with the progressive implementation of commercial air transportation. While the locations could be originally interconnected through highways ( paths, giving rise to geographical networks), transportation between those sites progressively shifted or was complemented by air transportation, with scale free characteristics. In the present work we introduce the path-star transformation ( in its uniform and preferential versions) as a means to model such network transformations where paths give rise to stars of connectivity. It is also shown, through optimal multivariate statistical methods (i.e. canonical projections and maximum likelihood classification) that while the US highways network adheres closely to a geographical network model, its path-star transformation yields a network whose topological properties closely resembles those of the respective airport transportation network.

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A classical theorem of H. Hopf asserts that a closed connected smooth manifold admits a nowhere vanishing vector field if and only if its Euler characteristic is zero. R. Brown generalized Hopf`s result to topological manifolds, replacing vector fields with path fields. In this note, we give an equivariant analog of Brown`s theorem for locally smooth G-manifolds where G is a finite group.

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Traditional venom immunotherapy uses injections of whole bee venom in buffer or adsorbed in Al (OH)(3) in an expensive, time-consuming way. New strategies to improve the safety and efficacy of this treatment with a reduction of injections would, therefore, be of general interest. It would improve patient compliance and provide socio-economic benefits. Liposomes have a long tradition in drug delivery because they increase the therapeutic index and avoid drug degradation and secondary effects. However, bee venom melittin (Mel) and phospholipase (PLA(2)) destroy the phospholipid membranes. Our central idea was to inhibit the PLA(2) and Mel activities through histidine alkylation and or tryptophan oxidation (with pbb, para-bromo-phenacyl bromide, and/or NBSN-bromosuccinimide, respectively) to make their encapsulations possible within stabilized liposomes. We strongly believe that this formulation will be nontoxic but immunogenic. In this paper, we present the whole bee venom conformation characterization during and after chemical modification and after interaction with liposome by ultraviolet, circular dichroism, and fluorescence spectroscopies. The PLA(2) and Mel activities were, measured indirectly by changes in turbidity at 400(nm), rhodamine leak-out, and hemolysis. The native whole bee venom (BV) presented 78.06% of alpha-helical content. The alkylation (A-BV) and succynilation (S-BV) of BV increased 0.44 and 0.20% of its alpha-helical content. The double-modified venom (S-A-BV) had a 0.74% increase of alpha-helical content. The BV chemical modification induced another change on protein conformations observed by Trp that became buried with respect to the native whole BV. It was demonstrated that the liposomal membranes must contain pbb (SPC:Cho:pbb, 26:7:1) as a component to protect them from aggregation and/or fusion. The membranes containing pbb maintained the same turbidity (100%) after incubation with modified venom, in contrast with pbb-free membranes that showed a 15% size decrease. This size decrease was interpreted as membrane degradation and was corroborated by a 50% rhodamine leak-out. Another fact that confirmed our interpretation was the observed 100% inhibition of the hemolytic activity after venom modification with pbb and NBS (S-A-BV). When S-A-BV interacted with liposomes, other protein conformational changes were observed and characterized by the increase of 1.93% on S-A-BV alpha-helical content and the presence of tryptophan residues in a more hydrophobic environment. In other words, the S-A-BV interacted with liposomal membranes, but this interaction was not effective to cause aggregation, leak-out, or fusion. A stable formulation composed by S-A-BV encapsulated within liposomes composed by SPC:Cho:pbb, at a ratio of 26:7:1, was devised. Large unilamellar vesicles of 202.5 nm with a negative surface charge (-24.29 mV) encapsulated 95% of S-A-BV. This formulation can, now, be assayed on VIT.

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The highly hydrophobic 5,10,15-triphenyl-20-(3-N-methylpyridinium-yl)porphyrin(3MMe)cationic species was synthesized, characterized and encapsulated in marine atelocollagen/xanthane gum microcapsules by the coacervation method. Further reduction in the capsule size, from several microns down to about 300-400 nm, was carried out successfully by ultrasonic processing in the presence of up to 1.6% Tween 20 surfactant, without affecting the distribution of 3MMe in the oily core. The resulting creamlike product exhibited enhanced photodynamic activity but negligible cytotoxicity towards HeLa cells. The polymeric micro/nanocapsule formulation was found to be about 4 times more phototoxic than the respective phosphatidylcholine lipidic emulsion, demonstrating high potentiality for photodynamic therapy applications. (C) 2009 Elsevier B.V. All rights reserved.