Efeito da densidade de plantio em soja na nodulação, concentração de nutrientes e rendimento.

Para manter a sustentabilidade dos sistemas agrícolas é importante aperfeiçoar o uso dos recursos naturais. Cerca de 87% das vagens de soja abortam antes de alcançar 2 cm de comprimento. Entretanto, maior luminosidade na parte inferior do dossel resultam num aumento na retenção de vagens e na produtividade da soja. A inoculação com Bradyrhizobium permite altos rendimentos da soja, dispensando o uso de N mineral, mas os resultados podem variar com a estirpe empregada. A densidade de plantio por sua vez modifica a absorção de nutrientes. Assim, o objetivo deste trabalho foi estudar o efeito combinado da diminuição na densidade (plantas/m2) e inoculação com duas estirpes de B. japonicum no rendimento, nodulação e concentração de nutrientes em folhas de soja. Para isso, realizou-se um ensaio a campo com diferentes densidades de plantio e estirpes de B. japonicum: 1) Testemunha sem inoculação, 04 pl./m; 2) Testemunha sem inoculação, 16 pl./m; 3) T + uréia e 04 pl./m; 4) T + uréia e 16 pl./m; 5) Inoculado com a estirpe CNPSO 2050 e 04 pl./m; 6) Inoculado com CNPSO 2050 e 16 pl./m; 7) Inoculado com SEMIA 5079 e 04 pl./m; 8) Inoculado com 5079 e 16 pl./m. As amostragens foram realizadas em V6 determinando-se número e massa seca de nódulos/planta, teores de N-P-KCa e Mg em folha. Na colheita foram avaliados rendimento, massa seca/grãos, número de grãos/pl, e n° de vagens com e sem grãos/pl. A diminuição do número de pl./ha não afetou a produtividade, sem que houvesse efeitos da inoculação na nodulação e na concentração de nutrientes em folhas. Entretanto, a densidade de plantio modificou os teores de P nas folhas.Fertbio

A Characterization of Bispecial Sturmian Words

A finite Sturmian word w over the alphabet {a,b} is left special (resp. right special) if aw and bw (resp. wa and wb) are both Sturmian words. A bispecial Sturmian word is a Sturmian word that is both left and right special. We show as a main result that bispecial Sturmian words are exactly the maximal internal factors of Christoffel words, that are words coding the digital approximations of segments in the Euclidean plane. This result is an extension of the known relation between central words and primitive Christoffel words. Our characterization allows us to give an enumerative formula for bispecial Sturmian words. We also investigate the minimal forbidden words for the set of Sturmian words.Comment: Accepted to MFCS 201

Pode Bradyrhizobium japonicum, em combinação com diferentes densidades de plantio de soja alterar componentes do rendimento?

A campo, baixas densidades de plantas de soja, de 80.000 pl./ha, estimulam a formação de grãos por planta, mas não a produtividade; contudo, diferentes estirpes de Bradyrhizobium não afetam esse parâmetro. Em casa de vegetação, densidades de 80.000 pl./ha incrementam o número de vagens/pl. em relação à densidade de 320.000 pl./ha, com diferenças entre estirpes

A continuous-time solver for quantum impurity models

We present a new continuous time solver for quantum impurity models such as those relevant to dynamical mean field theory. It is based on a stochastic sampling of a perturbation expansion in the impurity-bath hybridization parameter. Comparisons to quantum Monte Carlo and exact diagonalization calculations confirm the accuracy of the new approach, which allows very efficient simulations even at low temperatures and for strong interactions. As examples of the power of the method we present results for the temperature dependence of the kinetic energy and the free energy, enabling an accurate location of the temperature-driven metal-insulator transition.Comment: Published versio

The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files

We describe in detail the nature of XMM-Newton EPIC background and its various complex components, summarising the new findings of the XMM-Newton EPIC background working group, and provide XMM-Newton background blank sky event files for use in the data analysis of diffuse and extended sources. Blank sky event file data sets are produced from the stacking of data, taken from 189 observations resulting from the Second XMM-Newton Serendipitous Source Catalogue (2XMMp) reprocessing. The data underwent several filtering steps, using a revised and improved method over previous work, which we describe in detail. We investigate several properties of the final blank sky data sets. The user is directed to the location of the final data sets. There is a final data set for each EPIC instrument-filter-mode combination.Comment: Paper accepted by A&A 22 December 2006. 14 pages, 8 figures. Paper can also be found at http://www.star.le.ac.uk/~jac48/publications

An overview of the EXTraS project: Exploring the X-ray Transient and Variable Sky

The EXTraS project (Exploring the X-ray Transient and variable Sky) will harvest the hitherto unexplored temporal domain information buried in the serendipitous data collected by the European Photon Imaging Camera (EPIC) instrument onboard the ESA XMM-Newton X-ray observatory since its launch. This will include a search for fast transients, as well as a search and characterization of variability (both periodic and aperiodic) in hundreds of thousands of sources spanning more than nine orders of magnitude in time scale and six orders of magnitude in flux. X-ray results will be complemented by multiwavelength characterization of new discoveries. Phenomenological classification of variable sources will also be performed. All our results will be made available to the community. A didactic program in selected High Schools in Italy, Germany and the UK will also be implemented. The EXTraS project (2014-2016), funded within the EU/FP7 framework, is carried out by a collaboration including INAF (Italy), IUSS (Italy), CNR/IMATI (Italy), University of Leicester (UK), MPE (Germany) and ECAP (Germany).Comment: 6 pages, 1 figure. Proceedings of "Swift: 10 years of Discovery", to appear in Po

Long Range Magnetic Order and the Darwin Lagrangian

We simulate a finite system of $N$ confined electrons with inclusion of the Darwin magnetic interaction in two- and three-dimensions. The lowest energy states are located using the steepest descent quenching adapted for velocity dependent potentials. Below a critical density the ground state is a static Wigner lattice. For supercritical density the ground state has a non-zero kinetic energy. The critical density decreases with $N$ for exponential confinement but not for harmonic confinement. The lowest energy state also depends on the confinement and dimension: an antiferromagnetic cluster forms for harmonic confinement in two dimensions.Comment: 5 figure

Covalency, double-counting and the metal-insulator phase diagram in transition metal oxides

Dynamical mean field theory calculations are used to show that for late transition-metal-oxides a critical variable for the Mott/charge-transfer transition is the number of d-electrons, which is determined by charge transfer from oxygen ions. Insulating behavior is found only for a narrow range of d-occupancy, irrespective of the size of the intra-d Coulomb repulsion. The result is useful in interpreting 'density functional +U' and 'density functional plus dynamical mean field' methods in which additional correlations are applied to a specific set of orbitals and an important role is played by the 'double counting correction' which dictates the occupancy of these correlated orbitals. General considerations are presented and are illustrated by calculations for two representative transition metal oxide systems: layered perovskite Cu-based "high-Tc" materials, an orbitally non-degenerate electronically quasi-two dimensional systems, and pseudocubic rare earch nickelates, an orbitally degenerate electronically three dimensional system. Density functional calculations yield d-occupancies very far from the Mott metal-insulator phase boundary in the nickelate materials, but closer to it in the cuprates, indicating the sensitivity of theoretical models of the cuprates to the choice of double counting correction and corroborating the critical role of lattice distortions in attaining the experimentally observed insulating phase in the nickelates.Comment: 10+ pages, 5 figure

Ising transition driven by frustration in a 2D classical model with SU(2) symmetry

We study the thermal properties of the classical antiferromagnetic Heisenberg model with both nearest ($J_1$) and next-nearest ($J_2$) exchange couplings on the square lattice by extensive Monte Carlo simulations. We show that, for $J_2/J_1 > 1/2$, thermal fluctuations give rise to an effective $Z_2$ symmetry leading to a {\it finite-temperature} phase transition. We provide strong numerical evidence that this transition is in the 2D Ising universality class, and that $T_c\to 0$ with an infinite slope when $J_2/J_1\to 1/2$.Comment: 4 pages with 4 figure

The Role of Expenditures in Predicting Adequate Yearly Progress for Special Needs Students in Ohio

Although there exists a large body of research concerning the relationship between expenditure and student achievement, a lack of research exists analyzing this relationship as it pertains specifically to students with disabilities