The Role of Δ(1232)\Delta(1232) in Two-pion Exchange Three-nucleon Potential

In this paper we have studied the two-pion exchange three-nucleon potential $(2\pi E-3NP)$ using an approximate $SU(2) \times SU(2)$ chiral symmetry of the strong interaction. The off-shell pion-nucleon scattering amplitudes obtained from the Weinberg Lagangian are supplemented with contributions from the well-known $\sigma$-term and the $\Delta(1232)$ exchange. It is the role of the $\Delta$-resonance in $2\pi E-3NP$, which we have investigated in detail in the framework of the Lagrangian field theory. The $\Delta$-contribution is quite appreciable and, more significantly, it is dependent on a parameter Z which is arbitrary but has the empirical bounds $|Z| \leq 1/2$. We find that the $\Delta$-contribution to the important parameters of the $2\pi E-3NP$ depends on the choice of a value for Z, although the correction to the binding energy of triton is not expected to be very sensitive to the variation of Z within its bounds.Comment: 14 pages, LaTe

Crystallization and preliminary crystallographic studies of FoxE from Rhodobacter ferrooxidans SW2, an FeII oxidoreductase involved in photoferrotrophy

FoxE is a protein encoded by the foxEYZ operon of Rhodobacter ferrooxidans SW2 that is involved in Fe^II-based anoxygenic photosynthesis (`photoferrotrophy'). It is thought to reside in the periplasm, where it stimulates light-dependent Fe^II oxidation. It contains 259 residues, including two haem c-binding motifs. As no three-dimensional model is available and there is no structure with a similar sequence, crystals of FoxE were produced. They diffracted to 2.44 Å resolution using synchrotron radiation at the Fe edge. The phase problem was solved by SAD using SHELXC/D/E and the experimental maps confirmed the presence of two haems per molecule

Avaliação do padrão de visitação de Apis mellifera em três cultivares de meloeiro em Petrolina-PE, Brasil.

Para o cultivo do meloeiro, a presença de abelhas no período de florescimento é fundamental para garantir a polinização e incrementar a produção de frutos. Nesse sentido, objetivou-se verificar se há diferenças no comportamento de visitas e no recurso floral forrageado por Apis mellifera, em três cultivares de meloeiro. O trabalho foi desenvolvido no Campo Experimental da Embrapa Semiárido, em Petrolina-PE, com as cultivares do tipo Amarelo (BRS Araguaia), Pele-de-Sapo (P-33) e Cantaloupe (CAN-4), com observações da biologia floral, morfologia e comportamento de A. mellifera no período de 05h00 às 18h00. O pico de visitação foi diferente, ocorrendo de 11h00 às 12h00; 10h00 às 11h00 e de 15h00 às 16h00 para o tipo amarelo, cantaloupe e pele de sapo respectivamente. Quanto ao recurso floral forrageado, a coleta de néctar foi constante ao longo do dia, enquanto que a de pólen ocorreu principalmente no período da manhã. Quanto ao tipo floral, as flores hermafroditas receberam, de modo geral, mais visitas na cultivar do tipo amarelo e pele-de-sapo, sendo o inverso registrado para a do tipo cantaloupe. O maior número de visitas registrado nesse tipo floral pode ser atribuído às diferenças morfológicas, uma vez que suas flores são maiores e, portanto, poderiam ser mais atrativa

Transformação de feijoeiro com o gene oxalato oxidase para resistência ao mofo branco causado por Sclerotinia sclerotiorum (Lib.) de Bary.

No presente trabalho propôs-se transformar o feijoeiro com uma construção gênica para expressar o gene oxalato descarboxilase, objetivando a resistência ao fungo agente causal do mofo branco.CONAFE

Levantamento florístico de Caatinga arbustiva-arbórea no município de Lagoa Grande, PE.

Este trabalho teve como objetivo identificar a diversidade florística em fragmento de Caatinga arbustiva-arbórea, localizado nas proximidades de cultivo de videira (Vitis spp.), como subsídios a estudos de ecologia da paisagem

The one-pion-exchange three-nucleon force and the AyA_y puzzle

We consider a new three-nucleon force generated by the exchange of one pion in the presence of a 2N correlation. The underlying irreducible diagram has been recently suggested by the authors as a possible candidate to explain the puzzle of the vector analyzing powers $A_y$ and $iT_{11}$ for nucleon-deuteron scattering. Herein, we have calculated the elastic neutron-deuteron differential cross section, $A_y$, $iT_{11}$, $T_{20}$, $T_{21}$, and $T_{22}$ below break-up threshold by accurately solving the Alt-Grassberger-Sandhas equations with realistic interactions. We have also studied how $A_y$ evolves below 30 MeV. The results indicate that this new 3NF diagram provides one possible additional contribution, with the correct spin-isospin structure, for the explanation of the origin of this puzzle.Comment: revised version: We have also studied how Ay evolves below 30 MeV, 4 Pages (twocolumn), 2 figures, uses psfig, RevTe

Indicator value of anthropogenic vegetation in the Amazon.

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Indicator value of anthropogenic vegetation in the Amazon.

An evaluation of the effects of the experimental variants on the useful plants and the plantion systems calls for knlwledge of the extremely complex interaction between useful plants and spontaneous vegetation and of other environmental factors. A preliminary analysis of the spontaneous vegetation revealed that species compostion and structural traits of the vegetation were closely linked to the pre-use of the sites and recent management measure. In this study the data sets and some of the results of theira analysis to date are presented and discussed

Padrão de visitação de Apis mellifera em cultivo de melão do tipo amarelo com e sem cobertura plástica.

Suplemento. Edição dos Anais do 52 Congresso Brasileiro de Olericultura, Salvador, jul. 2012