Comment on ``BCS to Bose-Einstein crossover phase diagram at zero temperature for a d_{x^2-y^2} order parameter superconductor: Dependence on the tight-binding structure''

The work by Soares et al. [Phys. Rev. B 65, 174506 (2002)] investigates the BCS-BE crossover for d-wave pairing in the 2-dimensional attractive Hubbard model. Contrary to their claims, we found that a non-pairing region does not exist in the density vs coupling phase diagram. The gap parameter at T=0, as obtained by solving analytically as well as numerically the BCS equations, is in fact finite for any non-zero density and coupling, even in the weak-coupling regime.Comment: 7 pages, 1 figur

Avaliação, seleção e recomendação de cutlivares de arroz de várzeas em Minas Gerais de 1997 a 2002.

A fim de tornar a orizicultura irrigada uma atividade mais atrativa, a EPAMIG desenvolve, em parceria com a EMBRAPA Arroz e Feijão, pesquisas de melhoramento genético de arroz de várzeas com o objetivo de obter cultivares superiores às já recomendadas, tanto em produtividade como em aceitação comercial

Assessing the acute and chronic toxicity of exposure to naturally occurring oil sands deposits to aquatic organisms using Daphnia magna

In the Athabasca region, the oil sands are located at or near the surface making open-pit mining viable. In addition, the Athabasca River and its tributaries flow through these oil sands deposits, thereby receiving bitumen-associated contaminants through natural fluvial erosional and weathering processes. A key knowledge gap has been related to understanding both the magnitude and significance of the toxicological and ecological effects on aquatic organisms exposed to naturally occurring bitumen entering fluvial systems. Using the Daphnia magna model system, this study assessed the ecotoxicological effects of exposure to bitumen-elutriate treatments that simulated the early stages of fluvial/erosional exposure conditions. No significant among-site differences were observed in the survival of D. magna after 48 h exposure to elutriates produced from a 24 h extraction cycle, and chemical analysis indicated low concentration of a complex mixture of hydrocarbon and metal contaminants. In contrast, the same elutriates impaired reproduction and growth after a 21-day chronic exposure. F1 neonates from the chronic tests were tested for sensitivity to the reference substance potassium dichromate, revealing a decrease in their sensitivity. Inter-generational effects were also observed, with a significant decrease in subsequent neonate production, when daphnids were moved to a clean medium. Supplemental acute toxicity assays using 48 and 72 h bitumen extraction cycles progressively increased daphnid mortality after a 48-h exposure to the respective elutriates. This indicates that bitumen-associated contaminants are being liberated after initial input and fluvial washing (24 h), highlighting the need for future work to assess toxicity responses and associated elutriate water chemistry of a longer fluvial exposure time-series. This work contributes to our understanding of the possible effects of natural bitumen exposure on riverine aquatic ecosystems, providing new information to inform the delineation of baseline conditions to assess environmental change and the design of future regional effects-based monitoring programs.publishe

Value for cultivation and use of upland rice cultivars tested in multi-environments.

Data from 11 years of a breeding program for upland rice of the partner institutions Embrapa arroz e feijão, Epamig and UFLA conducted in 11 regions of Minas Gerais, were analyzed by the mixed model methodology. The genotypic correlations between environments ranged from medium to high, suggesting the predominance of simple interaction, but with differentiated ranking of genotypes at the different locations. Lines with specific performance, as well as lines of broad adaptation were identified. The performance of cultivar BRSMG Caravera, released in 2007, was superior to the others in terms of grain yield at all sites assessed, in other words, broad adaptation, in addition to a high genotypic performance

Potencialidades da produção de algodão pela agricultura familiar do Nordeste.

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Utilização do sistema fonte pontual na aplicação de cinco lâminas de irrigação e da fertirrigação em trigo.

Um sistema de irrigacao por aspersao denominado fonte pontual foi utilizado para estudar o efeito da lamina de irrigacao sobre a produtividade de trigo, apresentando bons resultados. O efeito de uma, duas e tres aplicacoes de nitrogenio apos o plantio, via fertirrigacao, e de cinco laminas de irrigacao sobre a produtividade e os fatores de producao do trigo foi testado. O numero de aplicacoes de nitrogenio proporcionou melhoras significativas no peso hectolitrico, no peso de mil graos e na facilidade de colheita, nao apresentando, entretanto, diferenca significativas na produtividade de graos

Joint effects of chlorpyrifos and mancozeb to the terrestrial isopod Porcellionides pruinosus: a multiple biomarker approach

The exposure to pesticides by non-target soil biota has long been regarded as a serious downside of modern agriculture regimes and subject of heated debate. Of utmost relevance is the exposure to pesticide mixtures since their effects have shown not to necessarily reflect the individual toxicity of its components and even the simple addition of effects may lead to consequences not clearly anticipated. In this work, a multiple biomarker approach was employed to identify the mechanistic and time-effects underlying several single and mixture treatments of chlorpyrifos and mancozeb in juveniles and adults of the terrestrial isopod Porcellionides pruinosus. The effects of both pesticides and mixture at recommended doses were mostly transitory under these controlled conditions and one-pulse exposure. While imbalances were identified on detoxification and oxidative stress-related enzymes, isopods generally showed the ability to recover until the end of the experiment. Juveniles showed, however, higher vulnerability than adults. The most notorious differences between life stages occurred in energy-related parameters where distinct performances and stress-handling behaviours were observed, suggesting higher metabolic costs in juveniles. Our results stress that understanding the time-dependence of the underlying mechanisms governing the joint-effects of pesticides can help assessing and anticipating mixtures’ effects. Moreover, it is also emphasized the importance taking life stage-related differences in consideration when evaluating the environmental risks of pesticides and pesticide mixtures

Diffractive production of dijets by double Pomeron exchange processes

A phenomenological description of diffractive dijet hadroproduction via double Pomeron exchange is presented. This description is based on a modified version of the Ingelman-Schlein model which includes the evolution of the Pomeron structure function and corrections regarding rapidity gap suppression effects. The same quark-dominant Pomeron structure function employed in a previous report to describe diffractive dijet and W production via single Pomeron processes is shown here to yield results consistent with the available data for double Pomeron processes as well.Comment: 4 pages, REVTEX4.

Physiological quality of mangaba seeds submitted to drying.

Made available in DSpace on 2017-07-19T23:53:53Z (GMT). No. of bitstreams: 1 Physiological.pdf: 330863 bytes, checksum: ea4c5112dd905d0b0528ddee7f43ab8a (MD5) Previous issue date: 2016-04-07201

Desempenho genotípico de linhagens de arroz de terras altas utilizando metodologia de modelos mistos.

Avaliou-se o desempenho de genótipos de arroz de terras altas utilizando metodologia de modelos mistos. Foram utilizados dados de produtividade de grãos dos ensaios de valor de cultivo e uso (VCU) do programa cooperativo de melhoramento de arroz de terras altas, desenvolvido em Minas Gerais, no período de 1997/1998 a 2007/2008. Realizou-se análise de deviance para verificar a significância dos efeitos de genótipos e suas interações com locais e anos, obtendo-se a estabilidade e a adaptabilidade genotípicas, com os métodos da média harmônica dos valores genotípicos. Os efeitos de genótipos, genótipos x locais e genótipos x anos foram estatisticamente significativos (p?0,05). As linhagens e cultivares mais estáveis foram: Curinga-3, CNA 8983, Guarani, BRSMG Caravera e CNA 8824. Com maior adaptabilidade, estabilidade e produtividade de grãos, simultaneamente, destacaram-se a BRSMG Caravera, Curinga-3, MG 1089, MG 1097 e CNA 8436. A BRSMG Caravera, entre todas as cultivares e linhagens avaliadas de 1997 a 2008, foi a de melhor desempenho pela MHPRVG, ou seja, maior estabilidade, adaptabilidade e produtividade de grãos, simultaneamente, proporcionando aos orizicultores de Minas Gerais alta segurança no seu cultiv