Nonlocal asymmetric exclusion process on a ring and conformal invariance

We present a one-dimensional nonlocal hopping model with exclusion on a ring. The model is related to the Raise and Peel growth model. A nonnegative parameter u controls the ratio of the local backwards and nonlocal forwards hopping rates. The phase diagram, and consequently the values of the current, depend on u and the density of particles. In the special case of half-lling and u = 1 the system is conformal invariant and an exact value of the current for any size L of the system is conjectured and checked for large lattice sizes in Monte Carlo simulations. For u > 1 the current has a non-analytic dependence on the density when the latter approaches the half-lling value.

Influence of the initial condition in equilibrium last-passage percolation models

In this paper we consider an equilibrium last-passage percolation model on an environment given by a compound two-dimensional Poisson process. We prove an L-2-formula relating the initial measure with the last-passage percolation time. This formula turns out to be a useful tool to analyze the fluctuations of the last-passage times along non-characteristic directions.

Exact field-driven interface dynamics in the two-dimensional stochastic Ising model with helicoidal boundary conditions

We investigate the interface dynamics of the two-dimensional stochastic Ising model in an external field under helicoidal boundary conditions. At sufficiently low temperatures and fields, the dynamics of the interface is described by an exactly solvable high-spin asymmetric quantum Hamiltonian that is the infinitesimal generator of the zero range process. Generally, the critical dynamics of the interface fluctuations is in the Kardar-Parisi-Zhang universality class of critical behavior. We remark that a whole family of RSOS interface models similar to the Ising interface model investigated here can be described by exactly solvable restricted high-spin quantum XXZ-type Hamiltonians. (C) 2012 Elsevier B.V. All rights reserved.

Food-Retail Development and the Myth of Everyday Low Prices: The Case of Brazil

This article analyses the changes in Brazilian food retailing by investigating the co-existence of, and the pricing variation across, large supermarket chains and small independent supermarkets. It uses cointegration tests to show that, despite the widespread belief that small supermarkets are inefficient and charge higher prices, they in fact charge lower prices. Accordingly, in contrast to the prevailing literature on food-retail development, competition in food retail is complex and cannot be described as a simple Darwinian process of market concentration. The article explores the survival of small retail and its consequences for the current discussion on modern food retail in developing countries.

A simple boiling-based DNA extraction for RAPD profiling of landfarm soil to provide representative metagenomic content

Landfarm soils are employed in industrial and petrochemical residue bioremediation. This process induces selective pressure directed towards microorganisms capable of degrading toxic compounds. Detailed description of taxa in these environments is difficult due to a lack of knowledge of culture conditions required for unknown microorganisms. A metagenomic approach permits identification of organisms without the need for culture. However, a DNA extraction step is first required, which can bias taxonomic representativeness and interfere with cloning steps by extracting interference substances. We developed a simplified DNA extraction procedure coupled with metagenomic DNA amplification in an effort to overcome these limitations. The amplified sequences were used to generate a metagenomic data set and the taxonomic and functional representativeness were evaluated in comparison with a data set built with DNA extracted by conventional methods. The simplified and optimized method of RAPD to access metagenomic information provides better representativeness of the taxonomical and metabolic aspects of the environmental samples.

Effect of a video on developing skills in undergraduate nursing students for the management of totally implantable central venous access ports

Background: Handling Totally Implantable Access Ports (TIAP) is a nursing procedure that requires skill and knowledge to avoid adverse events. No studies addressing this procedure with undergraduate students were identified prior to this study. Communication technologies, such as videos, have been increasingly adopted in the teaching of nursing and have contributed to the acquisition of competencies for clinical performance. Objective: To evaluate the effect of a video on the puncture and heparinization of TIAP in the development of cognitive and technical competencies of undergraduate nursing students. Method: Quasi-experimental study with a pretest-posttest design. Results: 24 individuals participated in the study. Anxiety scores were kept at levels 1 and 2 in the pretest and posttest. In relation to cognitive knowledge concerning the procedure, the proportion of correct answers in the pretest was 0.14 (SD=0.12) and 0.90 in the posttest (SD=0.05). After watching the video, the average score obtained by the participants in the mock session was 27.20. Conclusion: The use of an educational video with a simulation of puncture and heparinization of TIAP proved to be a strategy that increased both cognitive and technical knowledge. This strategy is viable in the teaching-learning process and is useful as a support tool for professors and for the development of undergraduate nursing students. (C) 2011 Elsevier Ltd. All rights reserved.

The importance of mesofauna and decomposition environment on leaf decomposition in three forests in southeastern Brazil

We examined the effects of soil mesofauna and the litter decomposition environment (above and belowground) on leaf decomposition rates in three forest types in southeastern Brazil. To estimate decomposition experimentally, we used litterbags with a standard substrate in a full-factorial experimental design. We used model selection to compare three decomposition models and also to infer the importance of forest type, decomposition environment, mesofauna, and their interactions on the decomposition process. Rather than the frequently used simple and double-exponential models, the best model to describe our dataset was the exponential deceleration model, which assumed a single organic compartment with an exponential decrease of the decomposition rate. Decomposition was higher in the wet than in the seasonal forest, and the differences between forest types were stronger aboveground. Regarding litter decomposition environment, decomposition was predominantly higher below than aboveground, but the magnitude of this effect was higher in the seasonal than in wet forests. Mesofauna exclusion treatments had slower decomposition, except aboveground into the Semi-deciduous Forest, where the mesofauna presence did not affect decomposition. Furthermore, the effect of mesofauna was stronger in the wet forests and belowground. Overall, our results suggest that, in a regional scale, both decomposers activity and the positive effect of soil mesofauna in decomposition are constrained by abiotic factors, such as moisture conditions.