Duality Symmetries in N=2 Heterotic Superstring

We review the derivation and the basic properties of the perturbative prepotential in N=2 compactifications of the heterotic superstring. We discuss the structure of the perturbative monodromy group and the embedding of rigidly supersymmetric monodromies associated with enhanced gauge groups, at both perturbative and non-perturbative level.Comment: Based on talks presented at several conferences. 12 pages, LaTe

Produção de mudas de palma-forrageira utilizando fragmentos de cladódios.

A palma (Opuntia ficus-indica L.) é uma das principais alternativas para alimentação de caprinos, ovinos e bovinos no Semiárido brasileiro. Contudo, o ataque da cochonilhado-carmim (Dactylopius opuntiae Cockerel) erradicou grande parte da área plantada, já que a maioria das variedades cultivadas são suscetíveis à praga. Três novas variedades resistentes à praga foram identificadas: Orelha-de-elefante mexicana, Miúda ou Doce e a variedade Mão-de-moça (clones IPA-Sertânea e PALMEPA-PB1). Contudo, a disponibilidade de material propagativo (cladódios ou raquetes) ainda é baixa, aumentando o preço da palma-semente. Assim, desenvolveu-se uma metodologia utilizando-se fragmentos (pedaços) de raquetes para a obtenção de novas mudas

On the Bound States of p- and (p+2)-Branes

We study bound states of D-p-branes and D-(p+2)-branes. By switching on a large magnetic field F on the (p+2) brane, the problem is shown to admit a perturbative analysis in an expansion in inverse powers of F. It is found that, to the leading order in 1/F, the quartic potential of the tachyonic state from the open string stretched between the p- and (p+2)-brane gives a vacuum energy which agrees with the prediction of the BPS mass formula for the bound state. We generalize the discussion to the case of m p-branes plus 1 (p+2)-brane with magnetic field. The T dual picture of this, namely several (p+2)-branes carrying some p-brane charges through magnetic flux is also discussed, where the perturbative treatment is available in the small F limit. We show that once again, in the same approximation, the tachyon condensates give rise to the correct BPS mass formula. The role of 't Hooft's toron configurations in the extension of the above results beyond the quartic approximation as well as the issue of the unbroken gauge symmetries are discussed. We comment on the connection between the present bound state problem and Kondo-like problems in the context of relevant boundary perturbations of boundary conformal field theories.Comment: 34 pages, Late

D-branes and the Conifold Singularity

We analyze in detail the description of type IIB theory on a Calabi-Yau three-fold near a conifold singularity in terms of intersecting D-branes. In particular we study the singularity structure of higher derivative $F$-terms of the form $F_g W^{2g}$ where $W$ is the gravitational superfield. This singularity is expected to be due to a one -loop contribution from a charged soliton hypermultiplet becoming massless at the conifold point. In the intersecting D-brane description this soliton is described by an open string stretched between the two D-branes. After identifying the graviphoton vertex as a closed string operator we show that $F_g$'s have the expected singularity structure in the limit of vanishing soliton mass.Comment: Latex file, 14 page

Caracterização parcial e avaliação da maturidade de composto e biofertilizante para a aplicação em áreas de produção orgânica.

Este trabalho teve por objetivo acompanhar o desenvolvimento e a determinação da maturidade de compostos e biofertilizantes

Multiloop divergences in the closed bosonic string theory

The structure of the divergences in the multiloop vacuum diagrams for the closed bosonic strings in the framework of the Polyakov covariant formalism is discussed. It is found, by an explicit computation, that all the divergences in the theory may be interpreted as due to tadpole diagrams in which the dilaton goes into the vacuum

Produção de toxinas inseticidas por isolados de Fusarlum spp. patogênicos a Dactylopius opuntiae Cockerel.

Neste trabalho buscou-se avaliar a produção de toxinas por seis isolados de Fusarium spp. obtidos em diferentes regiões do Agreste e Sertão pernambucano.Resumo 1733-2

Population dynamic of porcine parvovirus indicates decrease of variability

Projeto/Plano de Ação: 02.11.10.600-03

Infection of the coffee berry borer Hypothenemus hampei (Coleoptera : Scolytidae) by brazilian isolates of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae (Deuteromycotina : Hyphomycetes).

The virulence of four fungal isolates (three Beauveria bassiana and one Metarhizium anisopliae) against adultfemale coffee berry borers (CBB) was investigated. The most virulent isolate from initial bioassays, B. bassiana LPPI, with a LT50 of 3.4 days, was further investigated by application to berries prior to infestation and to berries already infested with CBB. At the highest concentration applied to berries (J x ]07 conidia mL -I), CBB mortality was 83% (berries inoculated prior to infestation ) and 62% (berries inoculated after infestation)