Modeling the optical constants of solids using acceptance-probability-controlled simulated annealing with an adaptive move generation procedure

The acceptance-probability-controlled simulated annealing with an adaptive move generation procedure, an optimization technique derived from the simulated annealing algorithm, is presented. The adaptive move generation procedure was compared against the random move generation procedure on seven multiminima test functions, as well as on the synthetic data, resembling the optical constants of a metal. In all cases the algorithm proved to have faster convergence and superior escaping from local minima. This algorithm was then applied to fit the model dielectric function to data for platinum and aluminum.

Molecular motion in miscible polymer blends .1. Motion in blends of PEO and PVPh studied by solid-state C-13 T-1 rho measurements

Changes in molecular motion in blends of PEO-PVPh have been studied using measurements of C-13 T-1 rho relaxation times. C-13 T-1 rho relaxation has been confirmed as arising from spin-lattice interactions by observation of the variation in T-1 rho with rf field strength and temperature. In the pure homopolymers a minimum in T-1 rho is observed at ca. 50 K above the glass transition temperatures detected by DSC. After blending, the temperature of the minimum in T-1 rho for PEO increased, while that for PVPh decreased, however, the minima, which correspond to the temperatures where the average correlation times for reorientation are close to 3.1 mu s, are separated by 45 K (in a 45% PEO-PVPh blend). These phenomena are explained in terms of the local nature of T-1 rho measurements. The motions of the individual homopolymer chains are only partially coupled in the blend. A short T-1 rho has been observed for protonated aromatic carbons, and assigned to phenyl rings undergoing large-angle oscillatory motion, The effects of blending, and temperature, on the proportion of rings undergoing oscillatory motion are analyzed.

Structure optimization combining soft-core interaction functions, the diffusion equation method, and molecular dynamics

Smoothing the potential energy surface for structure optimization is a general and commonly applied strategy. We propose a combination of soft-core potential energy functions and a variation of the diffusion equation method to smooth potential energy surfaces, which is applicable to complex systems such as protein structures; The performance of the method was demonstrated by comparison with simulated annealing using the refinement of the undecapeptide Cyclosporin A as a test case. Simulations were repeated many times using different initial conditions and structures since the methods are heuristic and results are only meaningful in a statistical sense.

Electron exchange coupling for single-donor solid-state spin qubits

Intervalley interference between degenerate conduction band minima has been shown to lead to oscillations in the exchange energy between neighboring phosphorus donor electron states in silicon [B. Koiller, X. Hu, and S. Das Sarma, Phys. Rev. Lett. 88, 027903 (2002); Phys. Rev. B 66, 115201 (2002)]. These same effects lead to an extreme sensitivity of the exchange energy on the relative orientation of the donor atoms, an issue of crucial importance in the construction of silicon-based spin quantum computers. In this article we calculate the donor electron exchange coupling as a function of donor position incorporating the full Bloch structure of the Kohn-Luttinger electron wave functions. It is found that due to the rapidly oscillating nature of the terms they produce, the periodic part of the Bloch functions can be safely ignored in the Heitler-London integrals as was done by Koiller, Hu, and Das Sarma, significantly reducing the complexity of calculations. We address issues of fabrication and calculate the expected exchange coupling between neighboring donors that have been implanted into the silicon substrate using an 15 keV ion beam in the so-called top down fabrication scheme for a Kane solid-state quantum computer. In addition, we calculate the exchange coupling as a function of the voltage bias on control gates used to manipulate the electron wave functions and implement quantum logic operations in the Kane proposal, and find that these gate biases can be used to both increase and decrease the magnitude of the exchange coupling between neighboring donor electrons. The zero-bias results reconfirm those previously obtained by Koiller, Hu, and Das Sarma.

Is maximizing resilience compatible with established ecological goal functions?

Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] used a simple phytoplanktonzooplankton-nutrient model and a genetic algorithm to determine the parameter values that would maximize the value of certain goal functions. These goal functions were to maximize biomass, maximize flux, maximize flux to biomass ratio, and maximize resilience. It was found that maximizing goal functions maximized resilience. The objective of this study was to investigate whether the Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] result was indicative of a general ecosystem principle, or peculiar to the model and parameter ranges used. This study successfully replicated the Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] experiment for a number of different model types, however, a different interpretation of the results is made. A new metric, concordance, was devised to describe the agreement between goal functions. It was found that resilience has the highest concordance of all goal functions trialled. for most model types. This implies that resilience offers a compromise between the established ecological goal functions. The parameter value range used is found to affect the parameter versus goal function relationships. Local maxima and minima affected the relationship between parameters and goal functions, and between goal functions. (C) 2003 Elsevier B.V. All rights reserved.

Radial Distortion Self-Calibration

In cameras with radial distortion, straight lines in space are in general mapped to curves in the image. Although epipolar geometry also gets distorted, there is a set of special epipolar lines that remain straight, namely those that go through the distortion center. By finding these straight epipolar lines in camera pairs we can obtain constraints on the distortion center(s) without any calibration object or plumbline assumptions in the scene. Although this holds for all radial distortion models we conceptually prove this idea using the division distortion model and the radial fundamental matrix which allow for a very simple closed form solution of the distortion center from two views (same distortion) or three views (different distortions). The non-iterative nature of our approach makes it immune to local minima and allows finding the distortion center also for cropped images or those where no good prior exists. Besides this, we give comprehensive relations between different undistortion models and discuss advantages and drawbacks.

Identificação de cepas de Escherichia coli enteropatogênicas em amostras de fezes, por reação de imunofluorescência direta

Foi realizado diagnóstico etiológico de casos de diarréia aguda em 121 pacientes internados na Clínica Pediátrica do Hospital da Santa Casa de São Paulo, Brasil. Foram utilizados os métodos bacteriológico clássico e de reação de imunofluorescência direta para a identificação de cepas de Escherichia coli enteropatogênicas: para estudo da sensibilidade das cepas de Escherichia coli isoladas, a diferentes antibióticos, foi usado o método de Concentração Inibitória Minima (CIM). Dos 56 casos positivos, 89,3% correspondiam a diferentes sorotipos enteropatogênicos de Escherichia coli, quando utilizada a técnica de imunofluorescência direta. O método bacteriológico clássico revelou ainda, nos 121 casos examinados, 4 cepas de Salmonella e 2 de Shigella. No estudo da CIM verificou-se maior sensibilidade das cepas de Escherichia coli enteropatogênicas estudadas à Gentamicina e Amikacina, do que aos outros antibióticos.

Fotossensibilidade e termoestabilidade de vacinas contra o sarampo (cepa Biken CAM-70) liofilizadas e/ou reconstituídas para administração

Três lotes de vacinas contra o sarampo, produzidos com a cepa de vírus Biken CAM-70, sob as formas liofilizada e reconstituída, pertencentes ao estoque da rede de vacinação da Secretaria de Estado da Saúde de São Paulo, Brasil, foram submetidos a testes de sensibilidade à luz, à temperatura de 2 a 8°C, e de termoestabilidade (protegidos da luz) às temperaturas de 28, 36,5 e 45°C, objetivando verificar por quanto tempo retinham sua potência, isto é, a concentração ideal recomendada para a cepa de vírus presente (3,70 log 10 DICT50 ou 5.000 doses infectantes de cultura de tecidos 50% por dose). A análise de retas de regressão ajustadas demonstrou que, de modo geral, tanto os lotes de vacinas liofilizados como os reconstituídos, mantidos às referidas temperaturas, expostos ou protegidos da luz, apresentaram queda de potência no decorrer do experimento, a qual foi mais acentuada para vacinas expostas à luz. Reconstituídos e mantidos a 2 a 8°C, os lotes não apresentaram homogeneidade no referente à sensibilidade à luz. Quando a fotossensibilidade de lotes de vacinas liofilizadas foi testada a 2 a 8°C eles mostraram-se mais sensíveis à degradação térmica quando expostos à luz do que quando protegidos dela. Entretanto, expostos ou protegidos, a potência foi inferior à minima aceita para a cepa Biken CAM-70. Às demais temperaturas, mesmo ao abrigo da luz, os dois lotes não retiveram potência mínima. Quanto às vacinas do lote 3, conservadas a 2 a 8°C, mantiveram-se de acordo com os requerimentos mínimos de potência durante 60 dias quando protegidas da luz, e durante 40 dias quando expostas a ela. A degradação térmica às demais temperaturas foi mais acentuada (28°C: 5 dias; 36,5°C: 2 dias; 45°C: 0,5 dia). Considerando a concentração viral mínima que vacinas produzidas com a cepa Biken CAM-70 devem conter para induzir efetiva resposta imunológica, os lotes de vacinas pesquisados (sob a forma liofilizada ou reconstituídos para administração) apresentaram, além de baixa estabilidade ao calor, pouca homogeneidade com relação a este parâmetro.

Macrófitas aquáticas de um lago marginal ao rio Embu-mirim, São Paulo, Brasil

Durante os anos de 1984/1985 obtiveram-se amostras sazonais para determinação de parâmetros físicos, químicos e biológicos de um lago marginal ao rio Embu-mirim, em Itapecerica da Serra, na bacia do reservatório de Guarapiranga (São Paulo, Brasil). Além de discutir os resultados obtidos quanto à flora de macrófitas aquáticas e suas relações com os outros parâmetros ambientais, são também analisados os efeitos da variação sazonal. As espécies encontradas estão presentes em diversos corpos d'água marginais, bem como ao longo do rio Embu-mirim, permitindo avaliar seu comportamento em corpos d'água semelhantes, da mesma bacia. A macrófita predominante foi Eichhornia crassipes (Mart.) Solms. Os resultados obtidos demostram a tendência de uma eutrofização acelerada e o risco de macrófitas potencialmente problemáticas, como E. crassipes e Salvinia auriculata, formarem camalotes de altas densidades, que podem chegar ao reservatório de Guarapiranga, através do rio Embu-mirim, causando problemas aos diversos usos da água.

Models with three Higgs doublets in the triplet representations of A(4) or S-4

We consider the quark sector of theories containing three scalar SU(2)(L) doublets in the triplet representation of A(4) (or S-4) and three generations of quarks in arbitrary A(4) (or S-4) representations. We show that for all possible choices of quark field representations and for all possible alignments of the Higgs vacuum expectation values that can constitute global minima of the scalar potential, it is not possible to obtain simultaneously nonvanishing quark masses and a nonvanishing CP-violating phase in the Cabibbo-Kobayashi-Maskawa quark mixing matrix. As a result, in this minimal form, models with three scalar fields in the triplet representation of A(4) or S-4 cannot be extended to the quark sector in a way consistent with experiment. DOI: 10.1103/PhysRevD.87.055010.

The shape of soap films and Plateau borders

We have calculated the shapes of flat liquid films, and of the transition region to the associated Plateau borders (PBs), by integrating the Laplace equation with a position-dependent surface tension γ(x), where 2x is the local film thickness. We discuss films in either zero or non-zero gravity, using standard γ(x) potentials for the interaction between the two bounding surfaces. We have investigated the effects of the film flatness, liquid underpressure, and gravity on the shape of films and their PBs. Films may exhibit 'humps' and/or 'dips' associated with inflection points and minima of the film thickness. Finally, we propose an asymptotic analytical solution for the film width profile.

Sensing Cloud Optimization applied to a non-convex constrained economical dispatch

Conferência: 39th Annual Conference of the IEEE Industrial-Electronics-Society (IECON) - NOV 10-14, 2013

A Circuncisão Ritual e Correcção Plástica da Fimose

Os AA. descrevem duas variantes da sua técnica pessoal de plastia do prepúcio para tratamento da Fimose. Utilizam uma variante da técnica de Duhamel, incisando a face dorsal do prepúcio em S itálico nos casos em que o anel estenosante é moderado e permite um deslizamento com exposição da glande. Nos casos de Fimose muito acentuada ressecam ad minima o prepúcio e fazem uma plastia YV na face dosrsal e se necessário uma pequena excisão da pele ventral excedente. Em ambas as técnicas conseguem um bom resultado estético, muitos dos casos são difíceis de distinguir de um prepúcio normal. As plastias com conservação do prepúcio tendem a ser mais utilizadas na cultura europeia contemporânea, onde os motivos rituais desapareceram e os hábitos de higiene se instalaram. Salvo por motivos religiosos ou indicações médicas precisas (diabetes, lesões dermatológicas, etc) a correcção da Fimose por técnicas mutilantes tende a desaparecer.

Estudos silviculturais de uma população natural de Copaifera multijuga Hayne - Leguminosae, na Amazônia Central. IV. Interpretação de dados fenológicos em relação a elementos climáticos

O autor apresenta informações fenológicas mensais de 82 matrizes de Copaiba (Copaifera multljuga Hayne), obtidas na Reserva Florestal Adolfo Ducke no período de fevereiro de 1979 a dezembro de 1985. São mostradas as percentagens de ocorrência das fases de floração, frutificação e mudança foliar e uma análise de regressão múltipla das fenofases com sete variáveis do clima (temperatura máxima, temperatura minima e temperatura média, em C°; umidade relativa em %; precipitação total em milímetros; insolação total em horas e evaporação líquida total em milímetros. A plena floração ocorreu na estação de chuvas e a frutificação (frutos maduros) apresentou picos máximos no fim da estação chuvosa e inicio da estação seca, comportamento que. difere da maioria das espécies arbóreas tropicais. A espécie portou-se como perenifólia e a fase de folhas novas antecedeu a da floração.

Observations on aquatic Macrophyte Dynamics In the Reservoir Of The Balbina Hydroelectric Powerplant, Amazonas State, Brazil

Between 1991 and 1995 aquatic macrophyte composition was observed in the lower part of the reservoir of the hydroelectric power plant of Balbina (Amazonas, Brazil). After closure of the dam in 1987, vegetation cover - mostly Eichhornia crassipes - was high, but was not quantified. After 1990 it declined rapidly with a characteristic succession pattern: Eichhornia ® Vincularia + Cyperaceae ® Salvinia. The Cyperaceae, and many other less dominant species, were mostly associated with drift wood, produced by the decomposing, emergent forest. Comparison of the chemical data of the Uatumã river before the construction of the dam (1983) with those of later years (1989 - 1995) suggests that the succession was the result of a relatively mild and short period of eutrophication, followed by declining nutrient levels. Annual variation of water levels, followed by aquatic and terrestrial decomposition of the marginal vegetation, may allow for the maintenance of relatively productive vegetation belts along the shore lines of islands and inundated stream valleys.