Seletividade do óleo de mamona em adultos do Trichogramma pretiosum Riley, 1978 (Hymenoptera: Trichogrammatidae).

Testes de seletividade tornaram-se obrigatórios quando o objetivo é estudar o efeito de um inseticida, mesmo que de origem vegetal, em organismos benéficos. Neste sentido, foi avaliada a seletividade do Óleo de mamona® nas concentrações de 1, 2, 3, 4, 5 e 6% (v/v), do detergente neutro Zupp® a 2% (v/v) (emulsificante para o óleo), do inseticida clorpirifós a 0,5 L i.a./ha (testemunha positiva) e da água destilada em adultos do T. pretiosum, de acordo com protocolos da IOBC/WPRS.Resumo

Magnetovac Cylinder to Magnetovac Torus

A method for mapping known cylindrical magnetovac solutions to solutions in torus coordinates is developed. Identification of the cylinder ends changes topology from R1 x S1 to S1 x S1. An analytic Einstein-Maxwell solution for a toroidal magnetic field in tori is presented. The toroidal interior is matched to an asymptotically flat vacuum exterior, connected by an Israel boundary layer.Comment: to appear in Class. Quant. Gra

On the differential geometry of curves in Minkowski space

We discuss some aspects of the differential geometry of curves in Minkowski space. We establish the Serret-Frenet equations in Minkowski space and use them to give a very simple proof of the fundamental theorem of curves in Minkowski space. We also state and prove two other theorems which represent Minkowskian versions of a very known theorem of the differential geometry of curves in tridimensional Euclidean space. We discuss the general solution for torsionless paths in Minkowki space. We then apply the four-dimensional Serret-Frenet equations to describe the motion of a charged test particle in a constant and uniform electromagnetic field and show how the curvature and the torsions of the four-dimensional path of the particle contain information on the electromagnetic field acting on the particle.Comment: 10 pages. Typeset using REVTE

Interplay between bending and stretching in carbon nanoribbons

We investigate the bending properties of carbon nanoribbons by combining continuum elasticity theory and tight-binding atomistic simulations. First, we develop a complete analysis of a given bended configuration through continuum mechanics. Then, we provide by tight-binding calculations the value of the bending rigidity in good agreement with recent literature. We discuss the emergence of a stretching field induced by the full atomic-scale relaxation of the nanoribbon architecture. We further prove that such an in-plane strain field can be decomposed into a first contribution due to the actual bending of the sheet and a second one due to edge effects.Comment: 5 pages, 6 figure

Circular Orbits in Einstein-Gauss-Bonnet Gravity

The stability under radial and vertical perturbations of circular orbits associated to particles orbiting a spherically symmetric center of attraction is study in the context of the n-dimensional: Newtonian theory of gravitation, Einstein's general relativity, and Einstein-Gauss-Bonnet theory of gravitation. The presence of a cosmological constant is also considered. We find that this constant as well as the Gauss-Bonnet coupling constant are crucial to have stability for $n>4$.Comment: 11 pages, 4 figs, RevTex, Phys. Rev. D, in pres

Contact lines for fluid surface adhesion

When a fluid surface adheres to a substrate, the location of the contact line adjusts in order to minimize the overall energy. This adhesion balance implies boundary conditions which depend on the characteristic surface deformation energies. We develop a general geometrical framework within which these conditions can be systematically derived. We treat both adhesion to a rigid substrate as well as adhesion between two fluid surfaces, and illustrate our general results for several important Hamiltonians involving both curvature and curvature gradients. Some of these have previously been studied using very different techniques, others are to our knowledge new. What becomes clear in our approach is that, except for capillary phenomena, these boundary conditions are not the manifestation of a local force balance, even if the concept of surface stress is properly generalized. Hamiltonians containing higher order surface derivatives are not just sensitive to boundary translations but also notice changes in slope or even curvature. Both the necessity and the functional form of the corresponding additional contributions follow readily from our treatment.Comment: 8 pages, 2 figures, LaTeX, RevTeX styl

Interface mediated interactions between particles -- a geometrical approach

Particles bound to an interface interact because they deform its shape. The stresses that result are fully encoded in the geometry and described by a divergence-free surface stress tensor. This stress tensor can be used to express the force on a particle as a line integral along any conveniently chosen closed contour that surrounds the particle. The resulting expression is exact (i.e., free of any "smallness" assumptions) and independent of the chosen surface parametrization. Additional surface degrees of freedom, such as vector fields describing lipid tilt, are readily included in this formalism. As an illustration, we derive the exact force for several important surface Hamiltonians in various symmetric two-particle configurations in terms of the midplane geometry; its sign is evident in certain interesting limits. Specializing to the linear regime, where the shape can be analytically determined, these general expressions yield force-distance relations, several of which have originally been derived by using an energy based approach.Comment: 18 pages, 7 figures, REVTeX4 style; final version, as appeared in Phys. Rev. E. Compared to v2 several minor mistakes, as well as one important minus sign in Eqn. (18a) have been cured. Compared to v1, this version is significantly extended: Lipid tilt degrees of freedom for membranes are included in the stress framework, more technical details are given, estimates for the magnitude of forces are mad

Uso da técnica TRAP (Target Region Amplification Polymorphism) para análises genéticas em mandioca.

O melhoramento genético integrado às técnicas da biotecnologia contribui principalmente para o aumento da produtividade das culturas comerciais, em sua adaptação aos variados ambientes e resistência a patógen

Bioprospecção de bactérias com potencial antagônico a fusarium spp. associado à morte de brachiaria brizantha

Há uma crescente busca nos últimos tempos por sistemas agropecuários que sejam produtivos, econômicos e sustentáveis. A síndrome da morte do capim Marandu (Brachiaria brizantha cv. Marandu) é um problema que vem crescendo nos últimos anos, um dos principais sinais de baixa sustentabilidade da pecuária brasileira. A morte das plantas forrageiras ocorre na época chuvosa, geralmente em solos mal drenados, devido a falta de adaptação da planta à baixa oxigenação das raízes, deixando-a suscetível ao ataque de fitopatógenos oportunistas. Diante da problemática, objetivou-se isolar e selecionar bactérias com potencial antagônico a Fusarium spp., um dos agentes fitopatogênicos que participam desse processo. Foram avaliados 10 sistemas, no período de chuva e seca: 1-F: floresta; 2-L: lavoura; 3-P: pecuária; 4-iPL: integração pecuária-lavoura; 5-iLP: integração lavoura-pecuária; 6-iLF: integração lavoura-floresta; 7-iPF: integração pecuária-floresta; 8-iLPF: lavoura e floresta por 2 anos e após pecuária e floresta por 2 anos; 9iLPF: pecuária e floresta por 2 anos e lavoura e floresta por 2 anos; 10-iLPF: integração lavoura-pecuária-floresta; além da mata nativa e área de pousio, distribuídos em blocos casualizados com 4 repetições. Os isolados bacterianos foram obtidos de amostras de solo diluídas, aplicadas em meio de cultura TSA 10% (Triptona soja ágar) e incubadas a 28ºC. Após a purificação os isolados foram armazenados em solução de glicerol 20% a -80°C. Foram testadas 20 bactérias em cada sistema. O método para avaliação de antagonismo foi o de cultura pareada em placa de Petri, por confronto direto, e em meio sólido BDA (Batata dextrose ágar). Na avaliação, foi considerado como positivo as bactérias que formaram halo de inibição ou quando o crescimento do corpo fúngico não encostou na bactéria. Dois isolados foram testados, Fusarium spp. isolado de planta de soja acometida (1) e Fusarium spp. isolado de solo onde ocorreu a morte da forrageira (2). Primeiramente, todos os isolados bacterianos foram testados contra o patógeno 1 e então, somente as bactérias antagônicas foram testadas contra o patógeno 2. Para o patógeno 1, na época da chuva, 7,5% dos isolados testados apresentaram antagonismo enquanto na seca esse valor foi maior (15%). Para o patógeno 2, nem todos os isolados positivos para o patógeno 1 foram eficientes no controle, demonstrando a ocorrência de interações entre isolados bacterianos e Fusarium spp. Quando considerados os sistemas, na chuva, para o patógeno 1, a mata apresentou maior número de isolados positivos (20%). Na seca, mata, 1-F e 8-iLPF para o patógeno 1, foram os que apresentaram maior número de positivos (25%). Dentre as épocas avaliadas, a seca teve mais bactérias antagonistas, e o tratamento 8-iLPF apresentou melhores resultados. O que demonstra possibilidade de encontrar um controlador biológico à Fusarium spp. neste sistema. Os sistemas mais biodiversos parecem favorecer o equilíbrio entre os microrganismos (antagonismo), o que pode reduzir ação do Fusarium spp. no capim Marandu. Isso deve ser evidenciado em análises posteriores com testes in vivo, a fim de comprovar e desenvolver novas biotecnologias. Palavras-chave: controle biológico, forragem, microbiologia

A Comprehensive Mechanism Reproducing the Mass and Mixing Parameters of Quarks and Leptons

It is shown that if, from the starting point of a universal rank-one mass matrix long favoured by phenomenologists, one adds the assumption that it rotates (changes its orientation in generation space) with changing scale, one can reproduce, in terms of only 6 real parameters, all the 16 mass ratios and mixing parameters of quarks and leptons. Of these 16 quantities so reproduced, 10 for which data exist for direct comparison (i.e. the CKM elements including the CP-violating phase, the angles $\theta_{12}, \theta_{13}, \theta_{23}$ in $\nu$-oscillation, and the masses $m_c, m_\mu, m_e$) agree well with experiment, mostly to within experimental errors; 4 others ($m_s, m_u, m_d, m_{\nu_2}$), the experimental values for which can only be inferred, agree reasonably well; while 2 others ($m_{\nu_1}, \delta_{CP}$ for leptons), not yet measured experimentally, remain as predictions. In addition, one gets as bonuses, estimates for (i) the right-handed neutrino mass $m_{\nu_R}$ and (ii) the strong CP angle $\theta$ inherent in QCD. One notes in particular that the output value for $\sin^2 2 \theta_{13}$ from the fit agrees very well with recent experiments. By inputting the current experimental value with its error, one obtains further from the fit 2 new testable constraints: (i) that $\theta_{23}$ must depart from its "maximal" value: $\sin^2 2 \theta_{23} \sim 0.935 \pm 0.021$, (ii) that the CP-violating (Dirac) phase in the PMNS would be smaller than in the CKM matrix: of order only $|\sin \delta_{CP}| \leq 0.31$ if not vanishing altogether.Comment: 37 pages, 1 figur