Efeito do expurgo com fosfina (Gastoxin) sobre a qualidade fisiológica de sementes de milho e sorgo.

O fosfato de aluminio (Gastoxin) vem sendo cada vez mais utilizado no controle de pragas de graos armazenados no Brasil. no entanto, ainda nao e conhecida a acao deste inseticida fumigante sobre a qualidade fisiologica de sementes. Com este objetivo, foi realizado um experimento com sementes de milho (Zea mays L.) e sorgo (Sorghum bicolor (L.) Moench). Utilizaram-se duas cultivares de milho (BR 105 e Maia XVII) e tres de sorgo (BR 005, BR 500 e BR 505) que sofreram de um a tres expurgos em duas dosagens (dosagen recomendada pelo fabricante - 5 comprimidos de Gastoxin por m3 e dobro desta dosagem). Os resultados mostraram que as cultivares de milho e sorgo possuiam caracteristicas distintas quanto a qualidade fisiologica, com sementes apresentando alto, medio e baixo vigor. O uso de inseticidas fumigante, AlPH3 (Gastoxin), ate o dobro da dosagem recomendada e ate tres expurgos, nao causou variações significativas no poder germinativo e nos tres testes de vigor aplicados as sementes destas especies. Baseado neste resultados, o Gastoxin pode ser utilizado no expurgo de sementes de milho e de sorgo, observadas as condicoes em que o experimento foi conduzido

Numerical solution of linear models in economics: The SP-DG model revisited

In general, complex and large dimensional models are needed to solve real economic problems. Due to these characteristics, there is either no analytical solution for them or they are not attainable. As a result, solutions can be only obtained through numerical methods. Thus, the growing importance of computers in Economics is not surprising. This paper focuses on an implementation of the SP-DG model, using Matlab,developed by the students as part of the Computational Economics course. We also discuss some of our teaching/learning experience within the course, given for the first time in the FEP Doctoral Programme in Economics.SP-DG Model, Output, Inflation, Numerical Simulation, Teaching of Economics

Conditions for non-monotonic vortex interaction in two-band superconductors

We describe a semi-analytic approach to the two-band Ginzburg-Landau theory, which predicts the behavior of vortices in two-band superconductors. We show that the character of the short-range vortex-vortex interaction is determined by the sign of the normal domain - superconductor interface energy, in analogy with the conventional differentiation between type-I and type-II superconductors. However, we also show that the long-range interaction is determined by a modified Ginzburg-Landau parameter $\kappa^*$, different from the standard $\kappa$ of a bulk superconductor. This opens the possibility for non-monotonic vortex-vortex interaction, which is temperature-dependent, and can be further tuned by alterations of the material on the microscopic scale

Produção e qualidade de frutos de cultivares de melancia sob irrigação por gotejamento.

Esta pesquisa foi conduzida no Campo Experimental da Embrapa Meio-Norte, Teresina, PI (05°05? S; 42°48?W e 74,4m), com o objetivo de avaliar a produção e qualidade dos frutos de três cultivares de melancia: o híbrido duplo Top Gun, o híbrido triplo Shadow e a cultivar Crimson Sweet, sob irrigação por gotejamento. Aplicou-se uma lâmina de irrigação diária equivalente a 100% de reposição da ET0. O delineamento experimental foi o de blocos casualizados com quatro repetições e duas amostras por parcela. Foram avaliados os seguintes parâmetros: peso médio dos frutos (kg), número de frutos por planta, produtividade (t.ha-1), fator de forma do fruto (dado pela relação entre a largura e o comprimento do fruto), sólidos solúveis totais (ºBrix), pH, conteúdo de vitamina C (mg/100 g de polpa) e acidez total titulável (% ácido cítrico). A cultivar Crimson Sweet apresentou diferença significativa para peso médio dos frutos (6,13 kg) e fator de forma do fruto (0,92), enquanto a cultivar Top Gun apresentou maior conteúdo de vitamina C (6,71 mg/100 g de polpa) e pH (5,21). A produtividade da variedade Crimson Sweet e Top Gun foi influenciada pelo número de frutos por planta

Modularity map of the network of human cell differentiation

Cell differentiation in multicellular organisms is a complex process whose mechanism can be understood by a reductionist approach, in which the individual processes that control the generation of different cell types are identified. Alternatively, a large scale approach in search of different organizational features of the growth stages promises to reveal its modular global structure with the goal of discovering previously unknown relations between cell types. Here we sort and analyze a large set of scattered data to construct the network of human cell differentiation (NHCD) based on cell types (nodes) and differentiation steps (links) from the fertilized egg to a crying baby. We discover a dynamical law of critical branching, which reveals a fractal regularity in the modular organization of the network, and allows us to observe the network at different scales. The emerging picture clearly identifies clusters of cell types following a hierarchical organization, ranging from sub-modules to super-modules of specialized tissues and organs on varying scales. This discovery will allow one to treat the development of a particular cell function in the context of the complex network of human development as a whole. Our results point to an integrated large-scale view of the network of cell types systematically revealing ties between previously unrelated domains in organ functions.Comment: 32 pages, 7 figure

Teleparallel origin of the Fierz picture for spin-2 particle

A new approach to the description of spin-2 particle in flat and curved spacetime is developed on the basis of the teleparallel gravity theory. We show that such an approach is in fact a true and natural framework for the Fierz representation proposed recently by Novello and Neves. More specifically, we demonstrate how the teleparallel theory fixes uniquely the structure of the Fierz tensor, discover the transparent origin of the gauge symmetry of the spin 2 model, and derive the linearized Einstein operator from the fundamental identity of the teleparallel gravity. In order to cope with the consistency problem on the curved spacetime, similarly to the usual Riemannian approach, one needs to include the non-minimal (torsion dependent) coupling terms.Comment: 5 pages, Revtex4, no figures. Accepted for publication in Phys. Rev.

Torsion Gravity: a Reappraisal

The role played by torsion in gravitation is critically reviewed. After a description of the problems and controversies involving the physics of torsion, a comprehensive presentation of the teleparallel equivalent of general relativity is made. According to this theory, curvature and torsion are alternative ways of describing the gravitational field, and consequently related to the same degrees of freedom of gravity. However, more general gravity theories, like for example Einstein-Cartan and gauge theories for the Poincare and the affine groups, consider curvature and torsion as representing independent degrees of freedom. By using an active version of the strong equivalence principle, a possible solution to this conceptual question is reviewed. This solution favors ultimately the teleparallel point of view, and consequently the completeness of general relativity. A discussion of the consequences for gravitation is presented.Comment: RevTeX, 34 pages. Review article to be published by Int. J. Mod. Phys.