Schwinger-Dyson equations and the quark-antiquark static potential

In lattice QCD, a confining potential for a static quark-antiquark pair can be computed with the Wilson loop technique. This potential, dominated by a linear potential at moderate distances, is consistent with the confinement with a flux tube, an extended and scalar system also directly observable in lattice QCD. Quantized flux tubes have also been observed in another class of confinement, the magnetic confinement in type II superconductors. On the other hand the solution of Schwinger Dyson Equations, say with the Landau gauge fixing and the truncation of the series of Feynman diagrams, already at the rainbow level for the self energy and at the ladder level for the Bethe Salpeter equation, provides a signal of a possible inverse quartic potential in momentum space derived from one gluon and one ghost exchange, consistent with confinement. Here we address the successes, difficulties and open problems of the matching of these two different perspectives of confinement, the Schwinger-Dyson perspective versus the flux tube perspective.Comment: 12 pages, 18 figures; talk presented at QCD-TNT, Trento, 7-11 sep 200

Water network design using a multiobjective real options framework

This is the final version of the article. Available from the publisher via the DOI in this record.Water distribution networks (WDNs) are an essential element of urban infrastructure. To achieve a good level of performance, the traditional design of WDNs based on expected future conditions should be replaced by a flexible design, using real options (ROs), that accounts for uncertainty by taking a broader view of possible future options. This work proposes a multiobjective ROs framework that sets out to reduce costs, minimize hydraulic pressure deficiency, and a third objective for minimizing carbon emissions. A multiobjective simulated annealing algorithm is used to identify the Pareto-optimal solutions, thus enabling a tradeoff analysis between solutions. These trade-offs show that a low pressure deficit solution is achieved by increasing investment at a much faster rate after a certain pressure deficit threshold (60 m). Also, the pressure deficits can only be reduced by increasing carbon emissions. Finally, this work also emphasizes the importance of including carbon emissions as a specific objective by comparing the results of the proposed model and another one that did not cover the environmental objective. The results show that it is possible to reduce CO2 for the same level of capital expenditure or the same level of network pressure deficits if carbon emissions are minimized in the optimization process.This study had the support of Fundac¸ao para a Ci ˜ encia e ˆ Tecnologia (FCT), through the Strategic Project UID/MAR/ 04292/2013 granted to MARE

Essential oil of Elyonurus muticus (Sprengel) O. Kuntze (Gramineae).

Twelve compounds were identified by GC.MS in the essential oil of Elyonurus muticus leaves, native in the Brazilian Pantanal. Spathulenol (18.6%), B-caryophyllene (17.9%) and camphene (11.5%) were the major components found in the oil

Clavibacter michiganensis subsp. insidiosus: bactéria quarentenária com risco para as culturas forrageiras no Brasil.

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Investigating interaction-induced chaos using time-dependent density functional theory

Systems whose underlying classical dynamics are chaotic exhibit signatures of the chaos in their quantum mechanics. We investigate the possibility of using time-dependent density functional theory (TDDFT) to study the case when chaos is induced by electron-interaction alone. Nearest-neighbour level-spacing statistics are in principle exactly and directly accessible from TDDFT. We discuss how the TDDFT linear response procedure can reveal the mechanism of chaos induced by electron-interaction alone. A simple model of a two-electron quantum dot highlights the necessity to go beyond the adiabatic approximation in TDDFT.Comment: 8 pages, 4 figure

Biomass and yield of peanut grown on tropical soil amended with sewage sludge contaminated with lead.

Application of sewage sludge with high lead (Pb) contents may pollute soils and contaminate crops. The objective of this work was to evaluate peanut responses to application of sewage sludge with varying Pb contents in order to supply phosphorus (P) to the plant. A greenhouse experiment was carried out with peanut grown on soil sample from a medium-textured Haplustox. Treatments were arranged in 3×2 + 2 factorial scheme, replicated three times, distributed in randomized block design, and consisted of: three Pb rates applied to soil with sewage sludge (3, 21, and 42 mg kg?1)×two times of sewage sludge application (30 days before peanut sowing and at the day of the sowing) + mineral fertilization + control (without sewage sludge and mineral fertilization). Sewage sludge was e?cient to supply P to peanut. Sewage sludge containing high rates of Pb, when applied, did not harm biomass and yield of the plant, but increased HCl-extractable Pb in soil and Pb content in shoot, roots, and pod husks. Increase of Pb content in pod husks may represent contamination risk of kernels and their products with fragments from husks detached during manipulation or industrial processing of peanuts

Avaliação de áreas com restrição legal de uso do solo em arranjos espaciais distintos de ocupação das terras no Nordeste do estado do Pará.

O avanço da fronteira agrícola e a consolidação de atividades produtivas em áreas florestais da Amazônia têm acarretado mudanças significativas na paisagem em algumas áreas críticas, ocorrendo muitas vezes sem um planejamento prévio, não considerando o uso sustentável do espaço. Por outro lado, o aumento populacional e a redução da disponibilidade de florestas secundárias em áreas de ocupação consolidada na Amazônia têm diminuído progressivamente o período de pousio agrícola e aumentado a pressão sobre zonas ripárias (Watrin et al., 2009). Esse cenário resulta em degradação do solo, impactos negativos sobre recursos hídricos e ameaça à diversidade biológica, contribuindo significativamente para reduzir a sustentabilidade de unidades rurais familiares..