A new correlator in quantum spin chains

We propose a new correlator in one-dimensional quantum spin chains, the $s-$Emptiness Formation Probability ($s-$EFP). This is a natural generalization of the Emptiness Formation Probability (EFP), which is the probability that the first $n$ spins of the chain are all aligned downwards. In the $s-$EFP we let the spins in question be separated by $s$ sites. The usual EFP corresponds to the special case when $s=1$, and taking $s>1$ allows us to quantify non-local correlations. We express the $s-$EFP for the anisotropic XY model in a transverse magnetic field, a system with both critical and non-critical regimes, in terms of a Toeplitz determinant. For the isotropic XY model we find that the magnetic field induces an interesting length scale.Comment: 6 pages, 1 figur

Irrigated rice area estimation using remote sensing techniques: Project's proposal and preliminary results

The development of a methodology for annual estimates of irrigated rice crop in the State of Rio Grande do Sul, Brazil, using remote sensing techniques is proposed. The project involves interpretation, digital analysis, and sampling techniques of LANDSAT imagery. Results are discussed from a preliminary phase for identifying and evaluating irrigated rice crop areas in four counties of the State, for the crop year 1982/1983. This first phase involved just visual interpretation techniques of MSS/LANDSAT images

Oxygen clamps in gold nanowires

We investigate how the insertion of an oxygen atom in an atomically thin gold nanowire can affect its rupture. We find, using ab initio total energy density functional theory calculations, that O atoms when inserted in gold nanowires form not only stable but also very strong bonds, in such a way that they can extract atoms from a stable tip, serving in this way as a clamp that could be used to pull a string of gold atoms.Comment: 4 pages; 4 figure

Perspectives in remote sensing in Brazil. An approach of the remote sensing applications to Earth resources surveys

Since the systematic use of earth surface data collection by orbital sensor systems started in 1972 with the launching of the North American LANDSAT satellite, a great effort has been made to assimilate, develop and transfer remote sensing technology (data acquisition and analysis) in its many applications in Brazil. The availability of sensor systems and existing data is considered approached, as well as those which will soon be available to the Brazilian researchers. The new systems of the LANDSAT-4, of the Columbia space shuttle and of the French satellites of the SPOT series are discussed. Some characteristics of the sensor system for the first Brazilian remote sensing satellite, to be launched by the end of the decade, are presented. Some LANDSAT-4 and SPOT simulation products are shown, emphasizing how the data obtained by these new satellites can be applied

Avaliação preliminar de cultivares de aveia na região de São Carlos-SP.

Resumo

Elastic transport through dangling-bond silicon wires on H passivated Si(100)

We evaluate the electron transmission through a dangling-bond wire on Si(100)-H (2x1). Finite wires are modelled by decoupling semi-infinite Si electrodes from the dangling-bond wire with passivating H atoms. The calculations are performed using density functional theory in a non-periodic geometry along the conduction direction. We also use Wannier functions to analyze our results and to build an effective tight-binding Hamiltonian that gives us enhanced insight in the electron scattering processes. We evaluate the transmission to the different solutions that are possible for the dangling-bond wires: Jahn-Teller distorted ones, as well as antiferromagnetic and ferromagnetic ones. The discretization of the electronic structure of the wires due to their finite size leads to interesting transmission properties that are fingerprints of the wire nature

Semiclassical approach to universality in quantum chaotic transport

The statistics of quantum transport through chaotic cavities with two leads is encoded in transport moments $M_m={\rm Tr}[(t^\dag t)^m]$, where $t$ is the transmission matrix, which have a known universal expression for systems without time-reversal symmetry. We present a semiclassical derivation of this universality, based on action correlations that exist between sets of long scattering trajectories. Our semiclassical formula for $M_m$ holds for all values of $m$ and arbitrary number of open channels. This is achieved by mapping the problem into two independent combinatorial problems, one involving pairs of set partitions and the other involving factorizations in the symmetric group.Comment: Published version. Changes in presentatio

Efeito do enxofre, aplicado na forma de gesso, sobre a produção e qualidade do capim colonião (Panicum maximum Jacq.)

Foram conduzidos em vasos com terra em casa de vegetação, ensaios com doses crescentes de enxofre na forma de gesso e nitrogênio em esquema fatorial com repetições em capim Colonião visando verificar o comportamento da gramínea em relação a produção e qualidade.Resumo

INPE's crop survey program using combined LANDSAT and aircraft data

There are no author-identified significant results in this report

Polpa de citros peletizada na alimentação de eqüinos.

O objetivo desta pesquisa; foi estudar três níveis de polpa de citros peletizada (PCP) em substituição ao milho em dietas,de potras em crescimento. Vinte e uma potras de raça Árabe e Cruza - Árabe, com peso inicial, de 278+-9,6kg, e 18 meses de idade, foram mantidos em baias individuais e diariamente exercitados. Foi usado delineamento inteiramente casualizado com três tratamentos, dieta basal (T,). 7,5% PCP (T,) e I5% PCP (T,), e sete repetições em que a potra foi a unidade experimental. 0 periodo experimental foi até l6 semanas. As dietas foram formuladas com 40% de volumoso (feno Cynodon cynodon Pers cv coast-Cross) e 60% de concetrado, 14,5% de proteínas brutas (PB) e 2,77Kcal/g de enegia digestivel matéria; seca (MS). Ganho em peso. 0 consumo VOLuntario ( gM/kg) e perimetro toracico dos animais não diferiram entre os tratamentos. A aItura média, na cernelha para animais. T(6,8+-0Cm) f0i superior à de T(3,4+-1,0cm) e T,('4,6+-1,0cm).O coeficiente de digesbilidade aparente da MS para T,(68,7+- 1,2% ) e T, (67,52+-1,2% ) foram superiores ao de T, (58,62+-1,2%). 0 mesmo fato ocorreu para a PB, sendo T, (77, I+- l,5% ) e T, (78,6+-l,5% )maiores que T,(70,8+-1,5 ). Para o teor de energia bruta T, (59,8+- 0,4% ) foi inferior T, (62.0+-0,4% ) e T, (6l,2+-0,4%). Nao houve diferencia entre os tratamentos para fibra em detergente neutro, fibra em detergente ácido e taxas de passagem daas fases solida e liquida das diferentes dietas. A polpa de citrus peletizada pode ser usada até o nivel de l5% em rações de potras em crescimento,sem influir no desempenho do animal