Lipodystrophy in HIV/AIDS patients with different levels of physical activity while on antiretroviral therapy

INTRODUÇÃO: A lipodistrofia relacionada ao uso de terapia antirretroviral (TARV) pode causar estigma estético e elevar o risco de doenças cardiovasculares. A atividade física pode ser uma alternativa válida para o tratamento e prevenção da lipodistrofia. Entretanto, poucos estudos tratam dessa temática. O objetivo deste estudo foi verificar a ocorrência de lipodistrofia relacionada ao uso de TARV em portadores de HIV/AIDS, com diferentes hábitos de atividades físicas. MÉTODOS: A casuística foi formada por 42 portadores de HIV em uso de TARV, do Centro de Testagem e Aconselhamento de Presidente Prudente. Para obtenção do nível de atividade física aplicou-se o Questionário Internacional de Atividade Física (IPAQ); a lipodistrofia foi diagnosticada pelo autorrelato do paciente e a confirmação médica. O percentual de gordura de tronco foi estimado pela absortometria por raio-X de dupla energia (DEXA). Foram coletados também dados referentes a sexo, idade, tempo de uso de TARV, valores de CD4 e carga viral. RESULTADOS: Verificou-se maior ocorrência de lipodistrofia no grupo sedentário quando comparado ao ativo, além de fator protetor da prática da atividade física em relação à ocorrência da lipodistrofia. O grupo com valores mais elevados de CD4 também apresentou maior proporção de sujeitos com lipodistrofia, além de maior proporção de ativos e de indivíduos com menor faixa etária. Os acometidos pela lipodistrofia apresentaram maiores valores de percentual de gordura de tronco, bem como, os sedentários em relação aos ativos. CONCLUSÕES: O estilo de vida fisicamente ativa resultou em efeito protetor para ocorrência da lipodistrofia relacionada ao uso da TARV.

Comparação entre diferentes métodos para estimativa de gordura corporal de ciclistas brasileiros de elite

O objetivo do estudo foi comparar diferentes métodos de estimativa de gordura corporal em ciclistas de elite. A amostra foi composta por 15 atletas de alto nível, do sexo masculino, com idade média de 28,6 anos. Gordura corporal foi estimada pela equação para espessura de dobras cutâneas (EDC), análise da bioimpedância elétrica (BIA) e absortometria de radiológica de dupla energia (DEXA) (utilizada como referência). O teste t pareado comparou as diferenças entre os métodos e o coeficiente de correlação intraclasse analisou o relacionamento entre os mesmos. Foi observado que os valores do percentual de gordura corporal estimado pela BIA (p= 0,029), mas não o estimado pela EDC (p= 0,094) diferiram das estimativas da DEXA. Dessa maneira, é possível concluir que EDC apresentou estimativas mais próximas daquelas fornecidas pelo DEXA.

Comportamento elétrico a alta temperatura de termistor cerâmico alfa-Fe2O3 com coeficiente de temperatura negativo

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

Análise estatística de padrões sísmicos: decomposição em multiescala

O processamento de registros sísmicos é uma tarefa muito importante dentro da Geofísica e que representa um desafio permanente na exploração de petróleo. Embora esses sinais forneçam uma imagem adequada da estrutura geológica do subsolo, eles são contaminados por ruídos e, o ground roll é a componente principal. Este fato exige um esforço grande para o desenvolvimento de metodologias para filtragem, Dentro desse contexto, este trabalho tem como objetivo apresentar um método de remoção do ruído ground roll fazendo uso de ferramentas da Física Estatística. No método, a Análise em Ondeletas é combinada com a Transformada de Karhunen-Loève para a remoção em uma região bem localizada. O processo de filtragem começa com a Decomposição em Multiescala. Essa técnica permite uma representação em tempo-escala fazendo uso das ondeletas discretas implementadas a filtros de reconstrução perfeita. O padrão sísmico original fica representado em multipadrões: um por escala. Assim, pode-se atenuar o ground roll como uma operação cirúrgica em cada escala, somente na região onde sua presença é forte, permitindo preservar o máximo de informações relevantes. A atenuação é realizada pela definição de um fator de atenuação Af. Sua escolha é feita pelo comportamento dos modos de energia da Transformada de Karhunen-Loève. O ponto correspondendo a um mínimo de energia do primeiro modo é identificado como um fator de atenuação ótimo

Estatística não-extensiva aplicada ao cálculo do calor específico eletrônico em estruturas quasiperiódicas

Systems whose spectra are fractals or multifractals have received a lot of attention in recent years. The complete understanding of the behavior of many physical properties of these systems is still far from being complete because of the complexity of such systems. Thus, new applications and new methods of study of their spectra have been proposed and consequently a light has been thrown on their properties, enabling a better understanding of these systems. We present in this work initially the basic and necessary theoretical framework regarding the calculation of energy spectrum of elementary excitations in some systems, especially in quasiperiodic ones. Later we show, by using the Schr¨odinger equation in tight-binding approximation, the results for the specific heat of electrons within the statistical mechanics of Boltzmann-Gibbs for one-dimensional quasiperiodic systems, growth by following the Fibonacci and Double Period rules. Structures of this type have already been exploited enough, however the use of non-extensive statistical mechanics proposed by Constantino Tsallis is well suited to systems that have a fractal profile, and therefore our main objective was to apply it to the calculation of thermodynamical quantities, by extending a little more the understanding of the properties of these systems. Accordingly, we calculate, analytical and numerically, the generalized specific heat of electrons in one-dimensional quasiperiodic systems (quasicrystals) generated by the Fibonacci and Double Period sequences. The electronic spectra were obtained by solving the Schr¨odinger equation in the tight-binding approach. Numerical results are presented for the two types of systems with different values of the parameter of nonextensivity q

Implementação da técnica de difração de elétrons de baixa energia

The purpose of this study is to describe the implementation of the Low Energy Electron Diffaction (LEED) technique in the Laboratory of Magnetic Nanostructures and Semiconductors of the Department of Theoretical and Experimental Physics of the Universidade Federal do Rio Grande do Norte (UFRN), Natal, Brazil. During this work experimental apparatus were implemented for a complete LEED set-up. A new vacuum system was also set up. This was composed of a mechanical pump, turbomolecular pump and ionic pump for ultra-high vacuum and their respective pressure measurement sensors (Pirani gauge for low vacuum measures and the wide range gauge -WRG); ion cannon maintenance, which is basically mini-sputtering, whose function is sample cleaning; and set-up, maintenance and handling of the quadrupole mass spectrometer, whose main purpose is to investigate gas contamination inside the ultra-high vacuum chamber. It should be pointed out that the main contribution of this Master's thesis was the set-up of the sample heating system; that is, a new sample holder. In addition to the function of sample holder and heater, it was necessary to implement the function of sustaining the ultra-high vacuum environment. This set of actions is essential for the complete functioning of the LEED technique

Efeitos da interação dipolar na nucleação de vórtices em nano-cilindros magnéticos

The effect of confinement on the magnetic structure of vortices of dipolar coupled ferromagnetic nanoelements is an issue of current interest, not only for academic reasons, but also for the potential impact in a number of promising applications. Most applications, such as nano-oscillators for wireless data transmission, benefit from the possibility of tailoring the vortex core magnetic pattern. We report a theoretical study of vortex nucleation in pairs of coaxial iron and Permalloy cylinders, with diameters ranging from 21nm to 150nm, and 12nm and 21nm thicknesses, separated by a non-magnetic layer. 12nm thick iron and Permalloy isolated (single) cylinders do not hold a vortex, and 21nm isolated cylinders hold a vortex. Our results indicate that one may tailor the magnetic structure of the vortices, and the relative chirality, by selecting the thickness of the non-magnetic spacer and the values of the cylinders diameters and thicknesses. Also, the dipolar interaction may induce vortex formation in pairs of 12nm thick nanocylinders and inhibit the formation of vortices in pairs of 21nm thick nanocylinders. These new phases are formed according to the value of the distance between the cylinderes. Furthermore, we show that the preparation route may control relative chirality and polarity of the vortex pair. For instance: by saturating a pair of Fe 81nm diameter, 21nm thickness cylinders, along the crystalline anisotropy direction, a pair of 36nm core diameter vortices, with same chirality and polarity is prepared. By saturating along the perpendicular direction, one prepares a 30nm diameter core vortex pair, with opposite chirality and opposite polarity. We also present a theoretical discussion of the impact of vortices on the thermal hysteresis of a pair of interface biased elliptical iron nanoelements, separated by an ultrathin nonmagnetic insulating layer. We have found that iron nanoelements exchange coupled to a noncompensated NiO substrate, display thermal hysteresis at room temperature, well below the iron Curie temperature. The thermal hysteresis consists in different sequences of magnetic states in the heating and cooling branches of a thermal loop, and originates in the thermal reduction of the interface field, and on the rearrangements of the magnetic structure at high temperatures, 5 produce by the strong dipolar coupling. The width of the thermal hysteresis varies from 500 K to 100 K for lateral dimensions of 125 nm x 65 nm and 145 nm x 65 nm. We focus on the thermal effects on two particular states: the antiparallel state, which has, at low temperatures, the interface biased nanoelement with the magnetization aligned with the interface field and the second nanoelement aligned opposite to the interface field; and in the parallel state, which has both nanoelements with the magnetization aligned with the interface field at low temperatures. We show that the dipolar interaction leads to enhanced thermal stability of the antiparallel state, and reduces the thermal stability of the parallel state. These states are the key phases in the application of pairs of ferromagnetic nanoelements, separated by a thin insulating layer, for tunneling magnetic memory cells. We have found that for a pair of 125nm x 65nm nanoelements, separated by 1.1nm, and low temperature interface field strength of 5.88kOe, the low temperature state (T = 100K) consists of a pair of nearly parallel buckle-states. This low temperature phase is kept with minor changes up to T= 249 K when the magnetization is reduced to 50% of the low temperature value due to nucleation of a vortex centered around the middle of the free surface nanoelement. By further increasing the temperature, there is another small change in the magnetization due to vortex motion. Apart from minor changes in the vortex position, the high temperature vortex state remains stable, in the cooling branch, down to low temperatures. We note that wide loop thermal hysteresis may pose limits on the design of tunneling magnetic memory cells

Fraturas e caminhos ótimos na rede de Barabasi-Albert

Following the study of Andrade et al. (2009) on regular square lattices, here we investigate the problem of optimal path cracks (OPC) in Complex Networks. In this problem we associate to each site a determined energy. The optimum path is defined as the one among all possible paths that crosses the system which has the minimum cost, namely the sum of the energies along the path. Once the optimum path is determined, at each step, one blocks its site with highest energy, and then a new optimal path is calculated. This procedure is repeated until there is a set of blocked sites forming a macroscopic fracture which connects the opposite sides of the system. The method is applied to a lattice of size L and the density of removed sites is computed. As observed in the work by Andrade et al. (2009), the fractured system studied here also presents different behaviors depending on the level of disorder, namely weak, moderated and strong disorder intensities. In the regime of weak and moderated disorder, while the density of removed sites in the system does not depend of the size L in the case of regular lattices, in the regime of high disorder the density becomes substantially dependent on L. We did the same type of study for Complex Networks. In this case, each new site is connected with m previous ones. As in the previous work, we observe that the density of removed sites presents a similar behavior. Moreover, a new result is obtained, i.e., we analyze the dependency of the disorder with the attachment parameter m

Propriedades físicas de bicamadas magnéticas

The magnetic order of bylayers composed by a ferromagnetic film (F) coupled with an antiferromagnetic film (AF) is studied. Piles of coupled monolayers describe the films and the interfilm coupling is described by an exchange interaction between the magnetic moments at the interface. The F has a cubic anisotropy while the AF has a uniaxial anisotropy. We analyze the effects of an external do magnetic field applied parallel to the interface. We consider the intralayer coupling is strong enough to keep parallel all moments of the monolayer an then they are described by one vector proportional to the magnetization of the layer. The interlayer coupling is represented by an exchange interaction between these vectors. The magnetic energy of the system is the sum of the exchange. Anisotropy and Zeeman energies and the equilibrium configuration is one that gives the absolute minimum of the total energy. The magnetization of the system is calculated and the influence of the external do field combined with the interfilm coupling and the unidirectional anisotropy is studied. Special attention is given to the region near of the transition fields. The torque equation is used to study dynamical behavior of these systems. We consider small oscillations around the equilibrium position and we negleet nonlinear terms to obtain the natural frequencies of the system. The dependence of the frequencies with the external do field and their behavior in the phase transition region is analized

Não vício assintótico, consistência forte e uniformemente forte de estimadores do tipo núcleo para dados direcionais sobre uma esfera unitária k-dimensional

In this work we studied the asymptotic unbiasedness, the strong and the uniform strong consistencies of a class of kernel estimators fn as an estimator of the density function f taking values on a k-dimensional sphere

Protocolo de Quioto e as possibilidades de inserção do Brasil no Mecanismo de Desenvolvimento Limpo por meio de projetos em energia limpa

Este artigo pretende estudar a inserção do Brasil no Mecanismo de Desenvolvimento Limpo (MDL) do Protocolo de Quioto, por meio de projetos em energia limpa, enfatizando a cooperação entre países desenvolvidos e em desenvolvimento e visando as ações práticas que esse mecanismo permite desenvolver para se alcançar o desenvolvimento sustentável e para conter o aquecimento global. Para isto, realizou-se extensa revisão bibliográfica dos acordos internacionais referentes às mudanças climáticas e de livros e artigos sobre a inserção brasileira no Protocolo de Quioto e no Mecanismo de Desenvolvimento Limpo. O Protocolo de Quioto é um acordo internacional que prevê a redução das emissões de gases de efeito estufa por intermédio de mecanismos flexibilizadores. O Mecanismo de Desenvolvimento Limpo é o único que permite a participação de países em desenvolvimento, para que eles reduzam emissões por meio de projetos que busquem o desenvolvimento sustentável. Neste contexto, o Brasil surge como um país atrativo para o recebimento destes projetos, por sua vocação para desenvolver fontes alternativas de energia e pela sua liderança no processo negociador do Protocolo. O MDL configura-se, portanto, em uma grande oportunidade para o Brasil, visto que esses projetos representam uma fonte de recursos financeiros para que o país busque o desenvolvimento sustentável, além de incentivarem um maior conhecimento científico e a adoção de novas tecnologias.

Algumas considerações sobre o ensino e a aprendizagem do conceito de energia

Neste artigo procuramos abordar alguns aspectos relevantes sobre o ensino e a aprendizagem do conceito de energia, tais como as concepções de energia do senso comum e as relações entre transformações de energia e meio ambiente, bem como destacar a viabilidade da utilização de textos com abordagens históricas e, finalmente, analisamos um texto interdisciplinar que relaciona energia e meio ambiente. Com relação ao referido texto, discutimos a possibilidade de o mesmo levar o estudante a um entendimento das noções fundamentais de energia, mediante a contextualização histórica, social, política, econômica e ambiental dessas noções.

Modelo de programação matemática para controle do crescimento da vegetação sob redes de distribuição de energia elétrica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação do comportamento termoanalítico e oxidativo do biodiesel de mamona

In this work biodiesel was gotten through the transesterification reaction using the oil of castor as source of triglycerides and using the methylic route for obtaining of esters. For the characterization of biodiesel and its mixtures with mineral diesel oil, physical chemical parameters and several analytical techniques had been used, as well as: gas chromatography (GC), nuclear magnetic resonance of proton (1H NMR), infrared spectroscopy (IR) and thermal analysis. The chromatography confirmed the complete reaction of esters in biodiesel presenting a 97,08% conversion. The 1H - NMR presented singlet in 3,6 ppm corresponding to the hydrogen of the group ester RCOO CH3. The infrared presented a strong band in 1741 cm-1 referring to stretching C=O of ester and an average band in 1175 cm-1 referring C O deformation. With the data of thermal analysis it was possible to observe the thermal and oxidative stability of the samples changing the atmospheres of synthetic air and nitrogen, where stages of the thermal decomposition had been verified and had been attributed to the volatilization and/or decomposition of the triacylglycerides. The thermal degradation of the samples was carried through 150 and 210°C during 1, 12, 24 and 48 hours and was observed change in the thermogravimetric profile, therefore an increase in the number of stages of the thermal decomposition also occurred indicating characteristic intermediate composites of polymerization, being this confirmed through the rheological study that presented brusque increase of viscosity. The kinetic study showed that the activation energy has the following order: biodiesel > mineral diesel oil > mixtures biodiesel/diesel

Hidróxidos duplos lamelares aplicados à obtenção de biodiesel

In this paper, the Layered Double Hydroxides (LDH s) type hydrotalcite were synthesized, characterized and tested as basic heterogeneous catalysts for the production of biodiesel by transesterification of sunflower oil with methanol. The synthesis of materials Layered Double Hydroxides (LDH s) by co-precipitation method from nitrates of magnesium and aluminum, and sodium carbonate. The materials were submitted to the variation in chemical composition, which is the amount of Mg2+ ions replaced by Al3+. This variation affects the characteristic physico-chemical and reaction the solid. The molar ratio varied in the range of 1:1 and 3:1 magnesium / aluminum, and their values between 0.2 and 0.33. This study aims to evaluate the influence of variation of molar ratio of mixed oxides derived from LDH s and the influence of impregnation of a material with catalytic activity, the KI, the rate of conversion of sunflower oil into methyl esters (biodiesel) through transesterification by heterogeneous catalysis. .The catalysts were calcined at 550 ° C and characterized by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy of X-ray (SEM / EDS), thermogravimetric analysis (TG) and test basicity. The transesterification reaction was performed for reflux is a mixture of sunflower oil and methanol with a molar ratio of 15:1, a reaction time of 4h and a catalyst concentration of 2% by weight. The physical-chemical characterization of sunflower oil and biodiesel obtained by the route methyl submitted according NBR, EN, ASTM. Subsequently, it was with the chromatographic and thermogravimetric characterizations of oils. The results of chromatographic analysis showed that the catalysts were effective in converting vegetable oil into biodiesel, in particular the type hydrotalcite KI-HDL-R1, with a conversion of 99.2%, indicating the strong influence of the chemical composition of the material, in special due to presence of potassium in the structure of the catalyst