Anderson localization on the Falicov-Kimball model with Coulomb disorder

The role of Coulomb disorder is analysed in the Anderson-Falicov-Kimball model. Phase diagrams of correlated and disordered electron systems are calculated within dynamical mean-field theory applied to the Bethe lattice, in which metal-insulator transitions led by structural and Coulomb disorders and correlation can be identified. Metallic, Mott insulator, and Anderson insulator phases, as well as the crossover between them are studied in this perspective. We show that Coulomb disorder has a relevant role in the phase-transition behavior as the system is led towards the insulator regime

Effects of band filling in the Anderson-Falicov-Kimball model

In this work, we study the Anderson-Falicov-Kimball model within the dynamical mean field theory for the Bethe lattice, restricting our analysis to the nonmagnetic case. The one-particle density of states is obtained by both arithmetic and geometric averages over disorder, since only the latter can detect localization in the absence of an energy gap. Varying the strengths of Coulomb interaction and disorder at zero temperature, we construct phase diagrams for this model, where we distinguish spectral regions with localized states, with extended states, or with a correlation-induced gap. With this, we identify metal-insulator transitions driven by correlation and disorder, as well as the competition between these effects. This is done for various band fillings, since our main interest here is to study how the variation of the electron density affects the phase diagrams previously obtained for half-filling. The picture revealed by the density of states is further checked by evaluating the static and dynamic conductivities, including temperature effects

Clogging of conventional driplines under the application of potassium chloride (white and red) with two water qualities

Neste trabalho, buscou-se avaliar a suscetibilidade de modelos de tubos gotejadores ao entupimento, quando expostos ao uso de cloreto de potássio (branco e vermelho), aplicados via diferentes qualidades de água. O experimento foi realizado no Laboratório de Irrigação do Departamento de Engenharia Rural da Escola Superior de Agricultura Luiz de Queiroz ESALQ/USP, por um período de nove meses, analisando o desempenho de oito modelos de tubos gotejadores convencionais, com quatro tratamentos e dez repetições, sendo cada repetição representada por um gotejador. Os tratamentos aplicados foram: (T1-Lg/B) água do lago x cloreto de potássio branco; (T2-Lg/V) água do lago x cloreto de potássio vermelho; (T3-Lb/B) água do laboratório x cloreto de potássio branco, e (T4-Lb/V) água do laboratório x cloreto de potássio vermelho. Os modelos de tubos gotejadores apresentaram desempenhos variáveis, sugerindo que a arquitetura interna dos gotejadores foi o fator determinante na caracterização do processo de entupimento. Não foi observado elevado entupimento com relação à aplicação dos cloretos de potássio branco e vermelho na ausência ou presença de fitoplâncton, mostrando que é possível utilizar cloreto de potássio vermelho em fertirrigação.This work aimed to evaluate the susceptibility of several dripline models against the clogging process when exposed to potassium chloride (white and red), applied through different water qualities (fertigation). The experiment was accomplished in three phases, at the Laboratory of Irrigation of the Department of Rural Engineering at ESALQ/USP, for a period of nine months, by analyzing the performance of eight conventional drip models, with four treatments and ten repetitions, being each repetition a dripper. The applied treatments were: (T1-Lg/B) water of the lake x chloride of white potassium; (T2-Lg/V) water of the lake x chloride of red potassium; (T3Lb/B) water of the laboratory x chloride of white potassium and (T4-Lb/V) water of the laboratory x chloride of red potassium. The dripline models presented variable performance, suggesting that internal architecture of emitters is a major factor related to clogging resistance for imposed treatments. It was not observed high clogging with the application of white or red potassium chloride, under different water quality conditions, showing that it is possible to use the red potassium chloride for fertigation without problems.Ministério da Ciência e TecnologiaConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Instituto Nacional de Ciência e Tecnologia em Engenharia da Irrigação (INCT-EI

Preserved Priming of Novel Objects in Patients with Memory Disorders

Amnesic patients perform poorly on explicit memory tests that require conscious recollection of recent experiences, but frequently show preserved facilitations of performance or priming effects on implicit memory tasks that do not require conscious recollection. We examined implicit memory for novel visual objects on an object decision test in which subjects decide whether structurally possible and impossible objects could exist in three-dimensional form. Patients with organic memory disorders showed robust priming effects on this task---object decision accuracy was higher for previously studied objects than for nonstudied objects---and the magnitude of priming did not differ from matched control subjects or college students. However, patients showed impaired explicit memory for novel visual objects on a recognition test. We argue that priming is mediated by the structural description system, a subsystem of the perceptual representation system, that operates at a presemantic level and is preserved in amnesic patients.Psycholog

Dependence of transition probabilities for non-linear photo-ionization of He atoms on the structure of the exciting radiation pulses

Sem informaçãoWe discuss the expected dependence of the probability transitions for 2-photon and 3-photon absorption in Helium gas on the spatial and temporal structure of the exciting radiation pulses. Regarding spatial structure, we assumed a Gaussian radial intensity distribution; we find, as expected, that the 2-photon and 3-photon processes become negligible at distances D away from the focus, where D is of the order of the beam waist FWHM. Regarding temporal structure, we compared transition probabilities for square, Gaussian and cosine squared temporal profiles; we find that for the same FWHM, Gaussian and cosine squared pulses give essentially the same transition probabilities, but the square pulses are about twice as efficient. We finally studied the effect of sharp versus smooth rise and fall edges in the light pulse; we find negligible correlation with the shape of the pulse edges, and strong correlation with the pulse FWHM, i.e., with pulse total energy, as might be expected.We discuss the expected dependence of the probability transitions for 2-photon and 3-photon absorption in Helium gas on the spatial and temporal structure of the exciting radiation pulses. Regarding spatial structure, we assumed a Gaussian radial intensity distribution; we find, as expected, that the 2-photon and 3-photon processes become negligible at distances D away from the focus, where D is of the order of the beam waist FWHM. Regarding temporal structure, we compared transition probabilities for square, Gaussian and cosine squared temporal profiles; we find that for the same FWHM, Gaussian and cosine squared pulses give essentially the same transition probabilities, but the square pulses are about twice as efficient. We finally studied the effect of sharp versus smooth rise and fall edges in the light pulse; we find negligible correlation with the shape of the pulse edges, and strong correlation with the pulse FWHM, i.e., with pulse total energy, as might be expected.353A632635Sem informaçãoSem informaçãoSem informaçã

Observations on Integral and Continuous U-duality Orbits in N=8 Supergravity

One would often like to know when two a priori distinct extremal black p-brane solutions are in fact U-duality related. In the classical supergravity limit the answer for a large class of theories has been known for some time. However, in the full quantum theory the U-duality group is broken to a discrete subgroup and the question of U-duality orbits in this case is a nuanced matter. In the present work we address this issue in the context of N=8 supergravity in four, five and six dimensions. The purpose of this note is to present and clarify what is currently known about these discrete orbits while at the same time filling in some of the details not yet appearing in the literature. To this end we exploit the mathematical framework of integral Jordan algebras and Freudenthal triple systems. The charge vector of the dyonic black string in D=6 is SO(5,5;Z) related to a two-charge reduced canonical form uniquely specified by a set of two arithmetic U-duality invariants. Similarly, the black hole (string) charge vectors in D=5 are E_{6(6)}(Z) equivalent to a three-charge canonical form, again uniquely fixed by a set of three arithmetic U-duality invariants. The situation in four dimensions is less clear: while black holes preserving more than 1/8 of the supersymmetries may be fully classified by known arithmetic E_{7(7)}(Z) invariants, 1/8-BPS and non-BPS black holes yield increasingly subtle orbit structures, which remain to be properly understood. However, for the very special subclass of projective black holes a complete classification is known. All projective black holes are E_{7(7)}(Z) related to a four or five charge canonical form determined uniquely by the set of known arithmetic U-duality invariants. Moreover, E_{7(7)}(Z) acts transitively on the charge vectors of black holes with a given leading-order entropy.Comment: 43 pages, 8 tables; minor corrections, references added; version to appear in Class. Quantum Gra

Astrophysics from data analysis of spherical gravitational wave detectors

The direct detection of gravitational waves will provide valuable astrophysical information about many celestial objects. Also, it will be an important test to general relativity and other theories of gravitation. The gravitational wave detector SCHENBERG has recently undergone its first test run. It is expected to have its first scientific run soon. In this work the data analysis system of this spherical, resonant mass detector is tested through the simulation of the detection of gravitational waves generated during the inspiralling phase of a binary system. It is shown from the simulated data that it is not necessary to have all six transducers operational in order to determine the source's direction and the wave's amplitudes.Comment: 8 pages and 3 figure