A Microscopic Mechanism for Muscle's Motion

The SIRM (Stochastic Inclined Rods Model) proposed by H. Matsuura and M. Nakano can explain the muscle's motion perfectly, but the intermolecular potential between myosin head and G-actin is too simple and only repulsive potential is considered. In this paper we study the SIRM with different complex potential and discuss the effect of the spring on the system. The calculation results show that the spring, the effective radius of the G-actin and the intermolecular potential play key roles in the motion. The sliding speed is about $4.7\times10^{-6}m/s$ calculated from the model which well agrees with the experimental data.Comment: 9 pages, 6 figure

Effect of random disorder and spin frustration on the reentrant spin glass phase and ferromagnetic phase in stage-2 Cu_{0.93}Co_{0.07}Cl_{2} graphite intercalation compound near the multicritical point

Stage-2 Cu$_{0.93}$Co$_{0.07}$Cl$_{2}$ graphite intercalation compound magnetically behaves like a reentrant ferromagnet near the multicritical point ($c_{MCP} \approx 0.96$). It undergoes two magnetic phase transitions at $T_{RSG}$ ($= 6.64 \pm 0.05$ K) and $T_{c}$ ($= 8.62 \pm 0.05$ K). The static and dynamic nature of the ferromagnetic and reentrant spin glass phase has been studied using DC and AC magnetic susceptibility. Characteristic memory phenomena of the DC susceptibility are observed at $T_{RSG}$ and $T_{c}$. The nonlinear AC susceptibility $\chi_{3}^{\prime}$ has a positive local maximum at $T_{RSG}$, and a negative local minimum at $T_{c}$. The relaxation time $\tau$ between $T_{RSG}$ and $T_{c}$ shows a critical slowing down: $\tau$ with $x = 13.1 \pm 0.4$ and $\tau_{0}^{*} = (2.5 \pm 0.5) \times 10^{-13}$ sec. The influence of the random disorder on the critical behavior above $T_{c}$ is clearly observed: $\alpha = -0.66$, $\beta = 0.63$, and $\gamma = 1.40$. The exponent of $\alpha$ is far from that of 3D Heisenberg model.Comment: 15 pages, 16 figures, submitted to Phys. Rev.

Avaliação de banana-passa obtida de frutos de diferentes genótipos de bananeira.

A industrialização pode ser uma opção para o aproveitamento de excedentes de produção e de frutos com aparência comprometida para consumo in natura, proporcionando aumento da vida-de-prateleira e agregação de valor ao produto. Frutos de diferentes variedades de bananeira (Musa spp.), obtidas em programas de melhoramento genético, podem apresentar características diferenciadas no que se refere à adequação à determinada forma de processamento. O presente trabalho teve o objetivo de avaliar o produto banana-passa obtido a partir de frutos de diferentes genótipos de bananeira: ?Caipira?; ?Nanica?; ?Pacovan? e seus híbridos PV03-44 e PV03-76; ?Prata Anã? e seus híbridos ?FHIA-18?, ?Pioneira? e ?Prata Graúda?. O processamento da banana-passa incluiu a aplicação de um tratamento antioxidante, contendo ácido ascórbico (0,25%) e ácido cítrico (0,30%), e uma desidratação osmótica, com sacarose (40%, a 70°C). A desidratação foi completada em secador de cabine com circulação forçada de ar. Os produtos obtidos foram avaliados quanto a aspectos físicos, físico-químicos, químicos e sensoriais. O maior rendimento de produção foi obtido utilizando-se a cultivar Pacovan. As bananas-passa tiveram boa aceitação sensorial, com médias superiores a 6 para os atributos aparência, cor, aroma, sabor e textura. A ?Pioneira? foi o genótipo com maior aceitação sensorial

Determination of W-boson Properties at Hadron Colliders

Methods for measuring the W-boson properties at hadron colliders are discussed. It is demonstrated that the ratio between the W- and Z-boson observables can be reliably calculated using perturbative QCD, even when the individual W- and Z-boson observables are not. Hence, by using a measured Z-boson observable and the perturbative calculation of the ratio of the W- over Z-boson observable, we can accurately predict the W-boson observable. The use of the ratio reduces both the experimental and theoretical systematic uncertainties substantially. Compared to the currently used methods it might, at high luminosity, result in a smaller overall uncertainty on the measured W-boson mass and width.Comment: 11 pages, 10 ps file

Sistemas de produção de cana-de-açúcar: avaliação de desempenho ambiental.

Resumo: A cultura da cana-de-açúcar no Brasil estende-se por uma área de 8,4 milhões de hectares e atinge uma produção anual de 642 milhões de toneladas. O setor sucroalcooleiro brasileiro tem um diferencial ambiental positivo, especialmente representado pela produção do etanol, combustível renovável, proveniente da cana-de-açúcar. O país é destaque mundial no uso de energias renováveis, que representam mais de 44% da sua matriz energética, e os produtos da cana-de-açúcar são responsáveis por 15,7% de toda a oferta de energia do país. No entanto, dada a grande extensão de território brasileiro e a enorme diversidade de ecossistemas, os sistemas de produção praticados no Brasil variam de forma significativa e, consequentemente, a eficiência da produção e os impactos ambientais também variam. Neste contexto, a Avaliação de Ciclo de Vida permite uma análise crítica do processo produtivo e dos impactos ambientais gerados, indicando pontos a serem melhorados para a obtenção de um sistema mais sustentável. No presente trabalho,foi avaliado o desempenho ambiental de sistema de produção de cana-de-açúcar praticados em duas regiões brasileiras: a) tradicional, Sudeste; e b) tradicional, Nordeste. Futuramente o estudo incluirá uma terceira região, de expansão no Centro-Oeste. Os resultados mostram que o sistema de produção adotado nas regiões tradicionais do Sudeste do país, mais tecnificado e instalado em áreas de solos mais férteis, tem melhor desempenho ambiental que o praticado em áreas tradicionais da região Nordeste. O emprego de grandes quantidades de fertilizantes sintéticos, bem como a queimada prévia à colheita, são práticas que contribuem grandemente para os impactos ambientais. Abstract: Sugarcane cultivation in Brazil extends over an area of 8.4 million hectares and reaches an annual yield of 642 million tons. The Brazilian sugarcane sector has a positive environmental advantage, represented especially by the production of ethanol, a renewable biofuel. Brazil is internationally recognized by the use of renewable energies, which account for over 44% of its energy matrix. The products of cane sugar are responsible for 15.7% of the country ́s energy supply. However, given the large expanses of the Brazilian territory and the huge diversity of ecosystems, the production systems practiced in Brazil are diverse and, consequently, the production efficiency and the environmental impacts can vary substantially. In this context, the Life Cycle Assessment provides a critical analysis of the production process and the associated environmental impacts, indicating points to be improved to obtain a more sustainable crop production system. In the present study, the environmental performance of the sugarcane was evaluated in two traditional Brazilian production areas, the Southeast and Northeast regions. A third region, the expansion areas in the Midwest Brazil, will be included in a future study. The production system adopted in the traditional regions of the Southeast, more intensive in technology and cultivated in areas of more fertile soils, have shown better environmental performance than those applied in traditional areas in the Northeast. The use of large amounts of synthetic fertilizers and burning prior to harvesting, were practices that contributed greatly to the environmental impacts of the sugarcane production systems

Relations among Supersymmetric Lattice Gauge Theories via Orbifolding

We show how to derive Catterall's supersymmetric lattice gauge theories directly from the general principle of orbifolding followed by a variant of the usual deconstruction. These theories are forced to be complexified due to a clash between charge assignments under U(1)-symmetries and lattice assignments in terms of scalar, vector and tensor components for the fermions. Other prescriptions for how to discretize the theory follow automatically by orbifolding and deconstruction. We find that Catterall's complexified model for the two-dimensional N=(2,2) theory has two independent preserved supersymmetries. We comment on consistent truncations to lattice theories without this complexification and with the correct continuum limit. The construction of lattice theories this way is general, and can be used to derive new supersymmetric lattice theories through the orbifolding procedure. As an example, we apply the prescription to topologically twisted four-dimensional N=2 supersymmetric Yang-Mills theory. We show that a consistent truncation is closely related to the lattice formulation previously given by Sugino.Comment: 20 pages, LaTeX2e, no figur

The primary structure of three hemoglobin chains from the indigo snake (Drymarchon corais erebennus, Serpentes): First evidence for αD chains and two β chain types in snakes

The hemoglobin of the indigo snake (Drymarchon corais erebennus, Colubrinae) consists of two components, HbA and HbD, in the ratio of 1:1. They differ in both their alpha and beta chains. The amino acid sequences of both alpha chains (alpha(A) and alpha(D)) and one beta chain (betaI) were determined. The presence of an alpha(D)chain in a snake hemoglobin is described for the first time. A comparison of all snake beta chain sequences revealed the existence of two paralogous beta chain types in snakes as well, which are designated as betaI and betaII type. For the discussion of the physiological properties of Drymarchon hemoglobin, the sequences were compared with those of the human alpha and beta chains and those of the closely related water snake Liophis miliaris where functional data are available. Among the heme contacts, the substitution alpha(D)58(E7)His-->Gln is unusual but most likely without any effect. The residues responsible for the main part of the Bohr effect are the same as in mammalian hemoglobins. In each of the three globin chains only two residues at positions involved in the alpha1/beta2 interface contacts, most important for the stability and the properties of the hemoglobin molecule, are substituted with regard to human hemoglobin. On the contrary, nine, eleven, and six alpha1/beta1 contact residues are replaced in the alpha(A), alpha(D), betaI chains, respectively