Topological Approach to Microcanonical Thermodynamics and Phase Transition of Interacting Classical Spins

We propose a topological approach suitable to establish a connection between thermodynamics and topology in the microcanonical ensemble. Indeed, we report on results that point to the possibility of describing {\it interacting classical spin systems} in the thermodynamic limit, including the occurrence of a phase transition, using topology arguments only. Our approach relies on Morse theory, through the determination of the critical points of the potential energy, which is the proper Morse function. Our main finding is to show that, in the context of the studied classical models, the Euler characteristic $\chi(E)$ embeds the necessary features for a correct description of several magnetic thermodynamic quantities of the systems, such as the magnetization, correlation function, susceptibility, and critical temperature. Despite the classical nature of the studied models, such quantities are those that do not violate the laws of thermodynamics [with the proviso that Van der Waals loop states are mean field (MF) artifacts]. We also discuss the subtle connection between our approach using the Euler entropy, defined by the logarithm of the modulus of $\chi(E)$ per site, and that using the {\it Boltzmann} microcanonical entropy. Moreover, the results suggest that the loss of regularity in the Morse function is associated with the occurrence of unstable and metastable thermodynamic solutions in the MF case. The reliability of our approach is tested in two exactly soluble systems: the infinite-range and the short-range $XY$ models in the presence of a magnetic field. In particular, we confirm that the topological hypothesis holds for both the infinite-range ($T_c \neq 0$) and the short-range ($T_c = 0$) $XY$ models. Further studies are very desirable in order to clarify the extension of the validity of our proposal

AtPIN: Arabidopsis thaliana Protein Interaction Network

<p>Abstract</p> <p>Background</p> <p>Protein-protein interactions (PPIs) constitute one of the most crucial conditions to sustain life in living organisms. To study PPI in Arabidopsis thaliana we have developed AtPIN, a database and web interface for searching and building interaction networks based on publicly available protein-protein interaction datasets.</p> <p>Description</p> <p>All interactions were divided into experimentally demonstrated or predicted. The PPIs in the AtPIN database present a cellular compartment classification (C³) which divides the PPI into 4 classes according to its interaction evidence and subcellular localization. It has been shown in the literature that a pair of genuine interacting proteins are generally expected to have a common cellular role and proteins that have common interaction partners have a high chance of sharing a common function. In AtPIN, due to its integrative profile, the reliability index for a reported PPI can be postulated in terms of the proportion of interaction partners that two proteins have in common. For this, we implement the Functional Similarity Weight (FSW) calculation for all first level interactions present in AtPIN database. In order to identify target proteins of cytosolic glutamyl-tRNA synthetase (Cyt-gluRS) (AT5G26710) we combined two approaches, AtPIN search and yeast two-hybrid screening. Interestingly, the proteins glutamine synthetase (AT5G35630), a disease resistance protein (AT3G50950) and a zinc finger protein (AT5G24930), which has been predicted as target proteins for Cyt-gluRS by AtPIN, were also detected in the experimental screening.</p> <p>Conclusions</p> <p>AtPIN is a friendly and easy-to-use tool that aggregates information on <it>Arabidopsis thaliana </it>PPIs, ontology, and sub-cellular localization, and might be a useful and reliable strategy to map protein-protein interactions in Arabidopsis. AtPIN can be accessed at <url>http://bioinfo.esalq.usp.br/atpin</url>.</p

Aplicação de nutrientes na bananeira via água de irrigação por microaspersão.

A área cultivada atualmente no pólo Petrolina (PE) - Juazeiro (BA) com a cultura da banana é aproximadamente 5.000 ha. O objetivo deste trabalho foi avaliar doses de nitrogênio e potássio aplicados via água de irrigação na cultura da bananeira no Submédio São Francisco. O nitrogênio e o potássio foram aplicados via água de irrigação uma vez por semana, utilizando-se injetor hidráulico. A adubação fosfatada foi dividida em partes iguais, aplicadas a cada seis meses. Ajustaram-se, pela análise de regressão, equações quadráticas, cuja melhor dose foi 340 kg ha -1 de N. O nitrogênio influenciou o peso e número de frutos por cacho. O potássio influenciou apenas o número de frutos por cacho

Leachate treatment process at a municipal stabilized landfill by catalytic ozonation: an exploratory study from Taguchi orthogonal array

Catalytic ozonation has been recognized in the scientific community as an efficient technique, reaching elevated rates of recalcitrant organic material mineralization, even at the presence of scavenger species of hydroxyl free radicals. This study presents the most significant factors involving the leachate treatment stabilized by the municipal landfill of the city of Guaratinguetá, State of São Paulo, Brazil, by using a catalytic ozonation activated by metallic ions Fe3+, Zn2+, Mn2+, Ni2+ and Cr3+. The Taguchi L16 orthogonal array and its associated statistical methods were also used in this study. Among the researched ions, the most notable catalysis was obtained with ferric ion, statistically significant in the reduction of COD with a confidence level of 99.5%.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Aptidão da cultura do mamoeiro para o Estado da Bahia.

O Brasil produziu aproximadamente 1,79 milhão de toneladas de frutos de mamão no ano de 2009. A Bahia, maior estado produtor do País, respondeu por aproximadamente 49,7% desse total, seguido do Espírito Santo (30,6%) e Ceará (5,85%). O cultivo do mamoeiro na Bahia é desenvolvido predominantemente em condições de sequeiro, sendo o estresse por deficiência hídrica o principal fator limitante para expansão da área de plantio e o principal critério utilizado nos trabalhos de zoneamento climático no Nordeste brasileiro.PDF. n. 101_11

The negative influences of the new brazilian forest code on the conservation of riparian forests

More than one million hectares of riparian forests were degraded or altered in Mato Grosso State (Brazil) up&nbsp;to 2009. The aim of the research is to set a comparative scenario to show differences in the quantification of&nbsp;environmental liabilities in riparian forest areas resulting from the change in native vegetation protection rules&nbsp;due to the transition between Laws 4771/65 and 12651/2012. Data collection took place in a marginal stretch&nbsp;of Vermelho River in Rondonópolis County, Mato Grosso State. The following data set was taken into consideration:&nbsp;aerial images derived from unmanned aerial vehicle, Rapid Eye satellite images and orbital images hosted&nbsp;at Google Earth. The spatial resolution of those images was compared. The aerial photos composed a mosaic&nbsp;that was photo-interpreted to generate land use and occupation classes. The riparian forest areas of a rural&nbsp;property were used as parameter, and their environmental situation was compared in 05 meter and 100 meter&nbsp;strips. Thus, by taking into consideration the current rules, 23,501 m2 of area ceased to be an environmental&nbsp;liability within the riparian forest and became a consolidated rural area. According to the previous Forest Code,&nbsp;in a different scenario, that is, in a set of rural properties, the public authority would receive USD 68,600.00 in&nbsp;fines. The new Brazilian Forestry Code of 2012, which replaces the previous one made in 1965, exempts those&nbsp;responsible for rural property from regenerating previously deforested native vegetation — an obligation established&nbsp;by older Forest Code. We have shown that the new Forest Code has diminished the legal responsibility of&nbsp;the rural owners in relation to the maintenance of forest fragments in their properties

A canonical transformation and the tunneling probability for the birth of an asymptotically DeSitter universe with dust

In the present work, we study the quantum cosmology description of closed Friedmann-Robertson-Walker models in the presence of a positive cosmological constant and a generic perfect fluid. We work in the Schutz's variational formalism. If one uses the scale factor and its canonically conjugated momentum as the phase space variables that describe the geometrical sector of these models, one obtains Wheeler-DeWitt equations with operator ordering ambiguities. In order to avoid those ambiguities and simplify the quantum treatment of the models, we introduce new phase space variables. We explicitly demonstrate that the transformation leading from the old set of variables to the new one is canonical. In order to show that the above canonical transformations simplify the quantum treatment of those models, we consider a particular model where the perfect fluid is dust. We solve the Wheeler-DeWitt equation numerically using the Crank-Nicholson scheme and determine the time evolution of the initial wave function. Finally, we compare the results for the present model with the ones for another model where the only difference is the presence of a radiative perfect fluid, instead of dust.Comment: Revtex4, 18 pages, 2 EPS figure