Dilution refrigeration and a calorimetric measurement of the quadruple coupling constant in rhenium metal

A dilution refrigerator has been constructed capable of producing steady state temperatures less than .075°K. The first part of this work is concerned with the design and construction of this machine. Enough theory is presented to allow one to understand the operation and critical design factors of a dilution refrigerator. The performance of our refrigerator is compared with the operating characteristics of three other dilution refrigerators appearing in the present literature.

The dilution refrigerator constructed was used to measure the nuclear contribution to the low temperature specific heat of a pure, single-crystalline sample of rhenium metal. Measurements were made in magnetic fields from 0 to 12.5 kOe for the temperature range .13°K - .52°K. The second part of this work discusses the results of these experiments. The expected nuclear contribution is not found when the sample is in the superconducting state. This is believed to be due to the long spin-lattice relaxation times in superconductors. In the normal state, for the temperature range studied, the nuclear contribution is given by A/T² where A = .061 ± .002 millijoules-K/mole. The value of A is found to increase to A = .077 ± .004 millijoules-K/mole when the sample is located in a magnetic field of 12.5 kOe.

From the measured value of A the splitting of the energy levels of the nuclear spin system due to the interaction of the internal crystalline electric field gradients with the nuclear quadrupole moments is calculated. A comparison is made between the predicted and measured magnetic dependence of the specific heat. Finally, predictions are made of future nuclear magnetic resonance experiments which may be performed to check the results obtained by calorimetery here and further, to investigate existing theories concerning the sources of electric field gradients in metals.

Factors affecting the susceptibility of salmonid fish to disease

A review article discussing the degree of susceptibility of fish to outbreaks of disease and whether, besides from changes in the physical and chemical characteristics of the environment, this susceptibility is instrumental in determining whether or not pathogenic challenge results in disease. The article summarises a decade of work on this subject at the Windermere laboratory of the Freshwater Biological Association and suggests possible directions for future research. The article covers experimental design, effects of environmental stress (including discussion on the hypothalamic-pituitary-interrenal (HPI) axis in salmonid fish), sexual maturation, research areas for future development and evolutionary considerations. There are a number of accompanying figures and images.

Topology optimization of silicon anode structures for lithium-ion battery applications

This thesis presents a topology optimization methodology for the systematic design of optimal multifunctional silicon anode structures in lithium-ion batteries. In order to develop next generation high performance lithium-ion batteries, key design challenges relating to the silicon anode structure must be addressed, namely the lithiation-induced mechanical degradation and the low intrinsic electrical conductivity of silicon. As such, this work considers two design objectives of minimum compliance under design dependent volume expansion, and maximum electrical conduction through the structure, both of which are subject to a constraint on material volume. Density-based topology optimization methods are employed in conjunction with regularization techniques, a continuation scheme, and mathematical programming methods. The objectives are first considered individually, during which the iteration history, mesh independence, and influence of prescribed volume fraction and minimum length scale are investigated. The methodology is subsequently extended to a bi-objective formulation to simultaneously address both the compliance and conduction design criteria. A weighting method is used to derive the Pareto fronts, which demonstrate a clear trade-off between the competing design objectives. Furthermore, a systematic parameter study is undertaken to determine the influence of the prescribed volume fraction and minimum length scale on the optimal combined topologies. The developments presented in this work provide a foundation for the informed design and development of silicon anode structures for high performance lithium-ion batteries.

Beam splitting of low-contrast binary gratings under second Bragg angle incidence

Beam splitting of low-contrast rectangular gratings under second Bragg angle incidence is studied. The grating period is between lambda and 2 lambda. The diffraction behaviors of the three transmitted propagating orders are illustrated by analyzing the first three propagating grating modes. From a simplified modal approach, the design conditions of gratings as a high-efficiency element with most of its energy concentrated in the -2nd transmitted order (similar to 90%) and of gratings as a 1 x 2 beam splitter with a total efficiency over 90% are derived. The grating parameters for achieving exactly the splitting pattern by use of rigorous coupled-wave analysis verified the design method. A 1 x 3 beam splitter is also demonstrated. Moreover, the polarization-dependent diffraction behaviors are investigated, which suggest the possibility of designing polarization-selective elements under such a configuration. The proposed concept of using the second Bragg angle should be helpful for developing new grating-based devices. (C) 2008 Optical Society of America.

Self-assembly of metallated TPP porphyrin by external dipyridyl ligands

Póster presentado en: XXII International Congress and General Assembly of the International Union of Crystallography (UICr), 22–30 Agosto 2011. Madrid, España

Self-assembly of metalloporphyrins: first TPP-bipy coordination polymer with CoII (TPP=meso-tetraphenylporphyrin and bipy=4,4´-bipyridine)

Póster presentado en: 11th International Symposium on Applied Bioinorganic Chemistry. 2-5 Diciembre 2011. Barcelona, España (ISABC 2011)

Pioneiros do design brasileiro no projeto de automóveis

Não se questiona que o design seja um saber naturalmente multidisciplinar. Os projetos da indústria automobilística ilustram esse ponto magistralmente: do ato de inventar à engenharia da produção; do design de exteriores aos interiores; das autopeças às diversas tintas. Projetos desenvolvidos em engenharia simultânea, produzidos em diversos países do mundo e montados onde quer que se mostre mais rentável. A moderna indústria automobilística mostra-se, nesse sentido, global. Mas como harmonizar os gostos e as legislações locais a essa estrutura produtiva internacional? Esta dissertação ilustra alguns aspectos da estratégia de projetos em design automobilístico tomando como base a experiência brasileira. Foram entrevistados os mais destacados designers brasileiros de automóveis dos pioneiros aos mais importantes profissionais contemporâneos. Embora as estratégias das empresas sejam diversas fato que impede uma única conclusão -, esta dissertação lança luzes sobre os desafios do desenvolvimento de projetos automobilísticos onde o projeto é global mas as vendas são locais.

Dynamic analysis of V-folded cavity for TEM00 operation of end-pumped solid-state laser

Based on graphic analysis design method of optical resonator, a simple design expression of V-folded cavity of end-pumped solid-state lasers with TEM00 operation is described, which satisfies two criterias of the resonator design. We give numerical simulation of spot size as a function of thermal focal length using this design approach whose advantages are validated experimentally.

Community Turnover of Wood-Inhabiting Fungi across Hierarchical Spatial Scales

For efficient use of conservation resources it is important to determine how species diversity changes across spatial scales. In many poorly known species groups little is known about at which spatial scales the conservation efforts should be focused. Here we examined how the community turnover of wood-inhabiting fungi is realised at three hierarchical levels, and how much of community variation is explained by variation in resource composition and spatial proximity. The hierarchical study design consisted of management type (fixed factor), forest site (random factor, nested within management type) and study plots (randomly placed plots within each study site). To examine how species richness varied across the three hierarchical scales, randomized species accumulation curves and additive partitioning of species richness were applied. To analyse variation in wood-inhabiting species and dead wood composition at each scale, linear and Permanova modelling approaches were used. Wood-inhabiting fungal communities were dominated by rare and infrequent species. The similarity of fungal communities was higher within sites and within management categories than among sites or between the two management categories, and it decreased with increasing distance among the sampling plots and with decreasing similarity of dead wood resources. However, only a small part of community variation could be explained by these factors. The species present in managed forests were in a large extent a subset of those species present in natural forests. Our results suggest that in particular the protection of rare species requires a large total area. As managed forests have only little additional value complementing the diversity of natural forests, the conservation of natural forests is the key to ecologically effective conservation. As the dissimilarity of fungal communities increases with distance, the conserved natural forest sites should be broadly distributed in space, yet the individual conserved areas should be large enough to ensure local persistence.

As histórias de coletivos para uma psicologia brasileira contemporânea

Este trabalho pretende problematizar as concepções de coletivo que se apresentam nos discursos da psicologia brasileira contemporânea. Tomamos como campo os artigos da revista Psicologia e Sociedade e construímos duas imagens: a imagem do coletivo representação é acompanhada por concepções naturalizantes das categorias com as quais trabalha. Nesta imagem de coletivo a separação entre indivíduo e sociedade é bem marcada e acaba produzindo construções abstratas dos seus fenômenos. Ao percorrer uma breve história da psicologia vemos esta surgir como uma tecnologia voltada para a ?gestão? dos coletivos, construindo e reproduzindo conhecimentos acerca dos indivíduos e do social. A imagem dos coletivos clandestinos é pautada em referências que desestabilizam as fronteiras impostas das ciências modernas e concebem tanto o indivíduo quanto o social efeito de uma produção simultânea, problematizando as fprmas de cpnhecimento das ciências tradicionais. A metodologia conta com a perspectiva histórica de Michel Foucault que afirma a primazia das relações de poder, e com as contribuições de Bruno Latour e suas conexões criando hibridismos. A proposta metodológica foi um importante instrumento ara romper com as barreiras separatistas, acentuando a presença do pesquisadpr como participante igual aos outros elementos do campo de pesquisa, enfatizando que o modo de pesquisar é com o outro e não sobre o outro. Desta forma As histórias de coletivos para uma psicologia brasileira pretende desnaturalizar modos de produzir conhecimento e categorias de coletivos herméticas. Para finalizar entre formas de fazer e perceber o coletivo temos o trabalho de campo atravessado pordois sociólogos, Emile Durkheim e Gabriel Tarde, contribuindo com as problematizações dos coletivos representação e clandestinos. Gabriel Tarde contribui produzindo uma concepção de coletivo processual, onde a imitação e a invenção ressaltam o caráter relacional do indivíduo e do social e os coloca numa produção de dupla emergência.

Control of polarization for a broadband dichroic filter at 45 degrees incidence

A method for the control of polarization for a broadband dichroic filter was reported and some design examples were elaborated. This method could be applied over a wide range of wavelengths and a wide range of polarizations in the transmission region. A nonpolaiizing broadband dichroic filter and a broadband dichroic filter with certain polarization were designed and fabricated by electron beam evaporation with ion beam assisted deposition. The experimental spectral performances showed good agreement with their theoretical curves. In addition, the application of the method was discussed. (c) 2007 Optical Society of America

O design de Victor Burton

Victor Burton é um designer que dedicou a maior parte do seu trabalho ao livro. A fascinação por este objeto começou ainda na infância devido ao contato com as obras raras da biblioteca da família, o que aguçou o desejo de se tornar designer exclusivamente para projetar livros. Sua atuação no mercado editorial brasileiro começou no final dos anos 1970, na editora Confraria dos Amigos do Livro. Como o maior interesse de Victor no livro é a relação entre texto e imagem, os livros iconográficos se tornaram seu principal objetivo e são nos livros desta natureza onde melhor conseguimos visualizar seu estilo. Victor desenvolveu uma linguagem gráfica própria que redefiniu o padrão do mercado editorial brasileiro. Numa época em que o projeto gráfico, principalmente a capa do livro, entre tantas cores e atrativos disputam a atenção do consumidor nas prateleiras das livrarias, já não é tão fácil identificar nem a editora nem a autoria do projeto gráfico e da capa. Entretanto, os livros de Victor Burton possuem um estilo que nos permite reconhecer sua assinatura. Desta forma, a questão que norteou este trabalho foi por que conseguimos identificar os livros do designer Victor Burton? Sendo assim, o objetivo deste trabalho foi enumerar e identificar os aspectos gráficos que caracterizam o estilo deste designer nos livros iconográficos. Para isso, nos baseamos no método descritivo desenvolvido por Guilherme Cunha Lima, em O Gráfico Amador. A partir das características levantadas, pudemos identificar os principais elementos que nos permite reconhecer a autoria dos trabalhos desenvolvidos por Victor Burton. O uso desses aspectos gráficos reflete o trabalho meticuloso do designer Victor Burton que consegue criar uma narrativa visual auxiliando a leitura do texto através de uma nova leitura gráfica, sobretudo nos livros iconográficos