Gravitational Geometric Phase in the Presence of Torsion

We investigate the relativistic and non-relativistic quantum dynamics of a neutral spin-1/2 particle submitted an external electromagnetic field in the presence of a cosmic dislocation. We analyze the explicit contribution of the torsion in the geometric phase acquired in the dynamic of this neutral spinorial particle. We discuss the influence of the torsion in the relativistic geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic quantum dynamics are studied and the influence of the torsion in the Aharonov-Casher and He-McKellar-Wilkens effects are discussed.Comment: 14 pages, no figur

Eficiência de anelamento aplicado como tratamento silvicultural em florestas manejadas na Amazônia Ocidental.

O manejo florestal em florestas primárias na Amazônia é, na maioria das vezes, limitado a sistemas silviculturais baseados no diâmetro mínimo de corte (DMC) e na extração de um número relativamente pequeno de espécies, reduzindo a população de árvores comerciais. A utilização de técnicas de impacto reduzido minimiza os impactos da extração, mas não necessariamente melhoram as baixas taxas de crescimento apresentadas por muitas espécies comerciais, nem asseguram o retorno dos volumes explorados para o próximo ciclo de corte. Por outro lado, estudos conduzidos nos trópicos têm mostrado que a aplicação de tratamentos silviculturais nas árvores do futuro, como cortes de liberação, corte de cipós e anelamento de competidoras, pode aumentar significativamente suas taxas de crescimento. De todos os métodos de anelamento, aquele em que se utiliza a motosserra é provavelmente o mais barato, rápido e fácil de implementar corretamente no campo. Os objetivos deste trabalho foram: avaliar os efeitos do anelamento sobre árvores comerciais e não comerciais indesejáveis; determinar os custos e eficiência do anelamento; e estabelecer os melhores níveis de resposta ao anelamento, em relação à classe de tamanho e iluminação de copa.bitstream/CPAF-AC-2010/23017/1/cot.172.pd

Dynamics of inelastically colliding rough spheres: Relaxation of translational and rotational energy

We study the exchange of kinetic energy between translational and rotational degrees of freedom for inelastic collisions of rough spheres. Even if equipartition holds in the initial state it is immediately destroyed by collisions. The simplest generalisation of the homogeneous cooling state allows for two temperatures, characterizing translational and rotational degrees of freedom separately. For times larger than a crossover frequency, which is determined by the Enskog frequency and the initial temperature, both energies decay algebraically like $t^{-2}$ with a fixed ratio of amplitudes, different from one.Comment: 5 pages, RevTeX, 2 eps figures, slightly expanded discussion, new figures with dimensionless units, added references, accepted for publication in PRE as a Rapid Com

Invasive frogs show persistent physiological differences to elevation and acclimate to colder temperatures

The coqui frog (Eleutherodactylus coqui) was introduced to the island of Hawai’i in the 1980s and has spread across much of the island. Concern remains that this frog will continue to expand its range and invade higher elevation habitats where much of the island’s endemic species are found. We determined whether coqui thermal tolerance and physiology change along Hawai’i’s elevational gradients. We measured physiological responses using a short-term experiment to determine baseline tolerance and physiology by elevation, and a long-term experiment to determine the coqui’s ability to acclimate to different temperatures. We collected frogs from low, medium, and high elevations. After both the short and long-term experiments, we measured critical thermal minimum (CTmin), blood glucose, oxidative stress, and corticosterone levels. CTmin was lower in high elevation frogs than low elevation frogs after the short acclimation experiment, signifying that they acclimate to local conditions. After the extended acclimation, CTmin was lower in frogs acclimated to cold temperatures compared to warm-acclimated frogs and no longer varied by elevation. Blood glucose levels were positively correlated with elevation even after the extended acclimation, suggesting glucose may also be related to lower temperatures. Oxidative stress was higher in females than males, and corticosterone was not significantly related to any predictor variables. The extended acclimation experiment showed that coquis can adjust their thermal tolerance to different temperatures over a 3-week period, suggesting the expansion of coqui into higher elevation habitats may still be possible, and they may not be as restricted by cold temperatures as previously thought

Estimation of interdomain flexibility of N-terminus of factor H using residual dipolar couplings

Characterization of segmental flexibility is needed to understand the biological mechanisms of the very large category of functionally diverse proteins, exemplified by the regulators of complement activation, that consist of numerous compact modules or domains linked by short, potentially flexible, sequences of amino acid residues. The use of NMR-derived residual dipolar couplings (RDCs), in magnetically aligned media, to evaluate interdomain motion is established but only for two-domain proteins. We focused on the three N-terminal domains (called CCPs or SCRs) of the important complement regulator, human factor H (i.e. FH1-3). These domains cooperate to facilitate cleavage of the key complement activation-specific protein fragment, C3b, forming iC3b that no longer participates in the complement cascade. We refined a three-dimensional solution structure of recombinant FH1-3 based on nuclear Overhauser effects and RDCs. We then employed a rudimentary series of RDC datasets, collected in media containing magnetically aligned bicelles (disk-like particles formed from phospholipids) under three different conditions, to estimate interdomain motions. This circumvents a requirement of previous approaches for technically difficult collection of five independent RDC datasets. More than 80% of conformers of this predominantly extended three-domain molecule exhibit flexions of < 40 °. Such segmental flexibility (together with the local dynamics of the hypervariable loop within domain 3), could facilitate recognition of C3b via initial anchoring and eventual reorganization of modules to the conformation captured in the previously solved crystal structure of a C3b:FH1-4 complex

Lippia sidoides essential oil at concentration of 0.25% provided improvements in microbiota and intestine integrity of Danio rerio.

Abstract: The study evaluated the effects of dietary supplementation with Lippia sidoides essential oil on the microbiota and intestinal morphology of Danio rerio. Resumo: O estudo avaliou os efeitos da suplementação dietária com óleo essencial de Lippia sidoides sobre a microbiota e a morfologia intestinal de Danio rerio. Para isso, 448 peixes foram distribuídos aleatoriamente em 28 tanques divididos em grupo controle alimentado com dieta comercial sem suplementação, grupo alimentado com dieta comercial contendo álcool de cereais e cinco grupos alimentados com dieta comercial contendo óleo essencial de L. sidoides (LSEO) em concentrações de 0,25%, 0,50%, 0,75%, 1,00% e 1,25%.Título em Português: O óleo essencial de Lippia sidoides em concentração 0,25% proporcionou melhorias na microbiota e integridade intestinal de Danio rerio

Data sharing in DHT based P2P systems

International audienceThe evolution of peer-to-peer (P2P) systems triggered the building of large scale distributed applications. The main application domain is data sharing across a very large number of highly autonomous participants. Building such data sharing systems is particularly challenging because of the "extreme" characteristics of P2P infrastructures: massive distribution, high churn rate, no global control, potentially untrusted participants... This article focuses on declarative querying support, query optimization and data privacy on a major class of P2P systems, that based on Distributed Hash Table (P2P DHT). The usual approaches and the algorithms used by classic distributed systems and databases forproviding data privacy and querying services are not well suited to P2P DHT systems. A considerable amount of work was required to adapt them for the new challenges such systems present. This paper describes the most important solutions found. It also identies important future research trends in data management in P2P DHT systems