12,608 research outputs found

    Experimental determination of the non-extensive entropic parameter qq

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    We show how to extract the qq parameter from experimental data, considering an inhomogeneous magnetic system composed by many Maxwell-Boltzmann homogeneous parts, which after integration over the whole system recover the Tsallis non-extensivity. Analyzing the cluster distribution of La0.7_{0.7}Sr0.3_{0.3}MnO3_{3} manganite, obtained through scanning tunnelling spectroscopy, we measure the qq parameter and predict the bulk magnetization with good accuracy. The connection between the Griffiths phase and non-extensivity is also considered. We conclude that the entropic parameter embodies information about the dynamics, the key role to describe complex systems.Comment: Submitted to Phys. Rev. Let

    Higher-Derivative Two-Dimensional Massive Fermion Theories

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    We consider the canonical quantization of a generalized two-dimensional massive fermion theory containing higher odd-order derivatives. The requirements of Lorentz invariance, hermiticity of the Hamiltonian and absence of tachyon excitations suffice to fix the mass term, which contains a derivative coupling. We show that the basic quantum excitations of a higher-derivative theory of order 2N+1 consist of a physical usual massive fermion, quantized with positive metric, plus 2N unphysical massless fermions, quantized with opposite metrics. The positive metric Hilbert subspace, which is isomorphic to the space of states of a massive free fermion theory, is selected by a subsidiary-like condition. Employing the standard bosonization scheme, the equivalent boson theory is derived. The results obtained are used as a guideline to discuss the solution of a theory including a current-current interaction.Comment: 23 pages, Late

    Baixas reservas energéticas corporais estão associadas à susceptibilidade ao jejum da espécie Glossophaga soricina

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    Morcegos nectarívoros que ocorrem na região Neotropical consomem grandes quantidades de carboidratos, e usam a energia obtida da dieta diretamente, a partir da glicose na circulação sanguínea. Esta adaptação sugere que morcegos nectarívoros tenham evoluído no sentido de apresentar adaptações fisiológicas que permitam o baixo armazenamento de reservas energéticas corporais. Nós testamos a hipótese de que morcegos Glossophaga soricina poupam o gasto energético envolvido com a formação de reservas energéticas teciduais, mesmo que isso represente uma arriscada suscetibilidade da espécie frente ao jejum. As concentrações de glicose apresentaram uma diminuição de 40% após 18 h de jejum. As concentrações de lipídios do músculo peitoral e do tecido adiposo, bem como as de ácidos graxos da carcaça e glicogênio hepático também diminuíram após 18 h de jejum. A incapacidade de manter a normoglicemia observada após o jejum de curto-prazo confirma que morcegos nectarívoros desta espécie não investem na formação de reservas energéticas, e apresentam, consequentemente, uma severa susceptibilidade ao jejum. Este estudo suporta a hipótese de que adaptações evolucionárias da espécie envolvem diminuição da massa corporal, reduzindo o custo energético do voo e aumentado o tempo de forrageamento.Neotropical nectar-feeding bats consume large amounts of sugar and use most of their energy-rich diet directly from the bloodstream, suggesting an adaptation towards lower body energy reserves. Here we tested the hypothesis that bats Glossophaga soricina spare the energy costs of storing energy reserves, even if this would represent a risky susceptibility during fasting. Blood glucose concentrations in 18 h fasted bats showed a 40% decrease. Breast muscle and adipose tissue lipids, as well as carcass fatty acids and liver glycogen, were also decreased following fasting. The inability to keep normoglycemia following a short-term fasting (i.e. 28 h) confirm that nectar bats invest little on storing energy reserves and show a severe fasting susceptibility associated to this pattern. Our study also support the general hypothesis that evolutionary specializations towards nectar diets involve adaptations to allow a decreased body mass, which reduces the energy costs of flight while increases foraging time

    Multi-criteria decision analysis applied to Brazilian grapevine genotype selection.

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    Developing new table grape cultivars that exhibit high yield and superior fruit quality is imperative to meet the escalating demands of the consumer market in the Lower-Middle S˜ao Francisco River Valley. The primary objective of Embrapa Semi´arido’s Active Germplasm Banks (AGB) for grapes is the conservation of Vitis sp. germplasm under semi-arid climatic conditions to make it available for research, particularly for the breeding and development of novel grape cultivars. This study aims to use Multi-Criteria Decision Analysis (MCDA), specifically the Preference Ranking Organization Method for Enrichment Evaluation (Promethee) II, to rank the grape genotypes of the Embrapa Semi´arido’s AGB, considering multiple criteria to define the primary grape varieties for the breeding program. The decision maker (DM) participated in all process stages, from validating qualitative and quantitative criteria to evaluating the criteria weights, and the decision matrix had 106 seeded and 50 seedless grape genotypes with 14 criteria. For visual analysis, we generated the GAIA Plane using the Visual Promethee Software. In the group of seeded grape cultivars, the three top- ranked genotypes were ’Italia Clone I′, ’Dona Maria’, and ’Italia Muscat’, while in the seedless group, the best-rated were ’BRS ´Isis’, ’BRS Linda’, and ’BRS Morena’. Our research demonstrated, for the first time, the evaluation of grape genotypes using MCDA method with qualitative and quantitative criteria

    Conservação ambiental forte alcançada através de sistemas agroflorestais multiestratificados: 2 - restauração de paisagens degradadas por meio de agroflorestas.

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    Foi avaliada a sustentabilidade ambiental em nível da paisagem de práticas de sistemas agroflorestais multiestratificados na região do Vale do Ribeira, SP e PR, na escala da unidade de produção agrícola familiar, baseando-se nos resultados de várias pesquisas publicadas e em mapas georrefenciados de uso e ocupação do solo atual e histórico. As práticas da agrofloresta, através da indução de sucessão agroflorestal e da sucessão florestal secundária natural, resultam em uma paisagem produtiva sob intenso processo de restauração. Assim considera-se o ?land sharing? baseado em agroflorestas agroecológicas como uma promissora estratégia de conservação ambiental.Edição do 1º Seminário de Agroecologia da América do Sul; 5º Seminário de Agroecologia de Mato Grosso do Sul; 4º Encontro de Produtores Agroecológicos de Mato Grosso do Sul; 1º Seminário de Sistemas Agroflorestais em Bases Agroecológicas de Mato Grosso do Sul, 2014, Dourados, MS - AGROECOL

    Peripapillary Retinal Nerve Fiber Layer Thickness and Peripheral Microcirculation in Raynaud’s Disease

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    Purpose: Normal-tension glaucoma has been associated with systemic vascular diseases such as peripheral vasospasm. This study aims to evaluate the influence of peripheral vasospasm on the thickness of the retinal nerve fiber layer (RNFL) in Raynaud's disease (RD), and the correlation between global RNFL and peripheral microcirculation features in RD patients. Methods: Observational cross-sectional study of 18 patients (35 eyes) with a diagnosis of RD followed in our clinic, and 20 healthy controls (39 eyes). RNFL parameters were obtained using spectral domain optical coherence tomography (SD-OCT Spectralis®, Heidelberg). Global and sectorial peripapillary RNFL thickness were registered. Age, gender, refractive error, best-corrected visual acuity and intraocular pressure were determined, and slit-lamp biomicroscopy and fundus examination were performed. Nailfold videocapillaroscopy (NC) was performed in the RD group to characterize capillary morphology and blood flow. Mann-Whitney and Fisher's exact tests were used for statistical analysis. Statistical significance level was set at p<0.05 (two-sided). Results: There was no significant difference in the global RNFL between RD patients and the control group (p=0.35). The presence of avascular areas in NC was associated with a lower global RNFL thickness (p=0.026). Conclusion: The association between avascular areas in NC and the lower global RNFL thickness in RD patients suggests that systemic vasospasm severity may be related to optic nerve damage propensity. Therefore, its presence in NC may identify RD patients at risk for optic nerve head damage. A larger sample with a long-term study is needed to support the clinical and therapeutic implications of our findings.info:eu-repo/semantics/publishedVersio

    Detailed study on stiffness and load characteristics of film-riding groove types using design of experiments

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    In the application of film-riding sealing technology, there are various groove features that can be used to induce hydrodynamic lift. However, there is little guidance in selecting the relative parameter settings in order to maximize hydrodynamic load and fluid stiffness. In this study, two groove types are investigated—Rayleigh step and inclined groove. The study uses a design of experiments approach and a Reynolds equation solver to explore the design space. Key parameters have been identified that can be used to optimize a seal design. The results indicate that the relationship between parameters is not a simple linear relationship. It was also found that higher pressure drops hinder the hydrodynamic load and stiffness of the seal suggesting an advantage for using hydrostatic load support in such conditions

    Practical method for table grape selevtion using multicriteria decision analysis.

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    The São Francisco Valley (Pernambuco-PE, Brazil) is of great importance for the local economy, since the region represents a large portion of Brazilian production and export of fresh grapes. Traditional methods of feasibility analysis involve only cost or productivity analyses, but for the grape growers there must be techniques and methods that assist decision making involving other criteria with characteristics of the grape. Yet, there is a noticeable lack of multi-criteria methods that assist the grower in making decisions for selection of commercial table grape cultivars for the feasibility analysis. Thus, the aim of the present study is to select table grape cultivars through multiple criteria, using a new method for eliciting scale constants: the Flexible and Interactive Tradeoff (FITradeoff), for the purpose of assisting a rural producer to expand production while minimizing inconsistencies in the decision-making process. With the assistance of a decision maker, the Decision Matrix and Consequence Table were constructed on Microsoft Excel® – composed by 11 criteria and 3 alternatives, all closed source grape cultivars (with patents). Then, the data were applied on the FITradeoff software for the ranking problematic. Thus, it was possible to arrive at a ranking of the best alternatives, where the cultivar Timpson (SNFL) (U2) was found to be the optimal solution proposed for the rural producer. The application of FITradeoff provided a satisfactory result with little time and effort spent, leading to a final suggestion for the decision maker. In addition, at the end of the process, it provided graphical visualization of the performance and dominance of each criterion selected, as well as a ranking of the grape cultivars through the Hasse Diagram, with the order of the best alternatives. Ordering the grape genotypes considering Multi-Criteria Decision Analysis methods is crucial to selection of commercial table grape cultivars. The method can be applied to other segments of agriculture that require multi-criteria evaluations

    Protocolo para desenvolvimento de marcadores microssatélites.

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    bitstream/CENARGEN/24380/1/ct020.pd

    Surface-Modified Bacterial Cellulose with Mercaptosilane as a Multifunctional Platform

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    Cellulose synthesized by bacteria has unique properties such as high water retention capacity, biocompatibility, biodegradability and flexibility. Nevertheless, modification of this biomaterial is required in order to obtain multifunctional materials, which may be applied in several high-value added products, as catalytic and cell culture platforms. The surface of bacterial cellulose (BC) can be modified by several approaches, namely: (i) physical treatment by plasma, (ii) adsorption of molecules onto BC surface, and (iii) chemical modification. In this sense, the aim of this study was to modify the BC surface by silanization reaction at room temperature using a mixture of ethanol and water, using two different protocols. Thus, BC membranes synthesized by Komagataeibacter xylinus were modified by adding the thiol (SH) functional group with (3-mercaptopropyl)trimethoxysilane under mild conditions. The produced materials were analyzed by elemental analysis, ATR-FTIR, TGA and SEM, and the successful modification was proven by elemental analysis and SEM.
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