Quantum Hamiltonians with Quasi-Ballistic Dynamics and Point Spectrum

Consider the family of Schr\"odinger operators (and also its Dirac version) on $\ell^2(\mathbb{Z})$ or $\ell^2(\mathbb{N})$ $$H^W_{\omega,S}=\Delta + \lambda F(S^n\omega) + W, \quad \omega\in\Omega,$$ where $S$ is a transformation on (compact metric) $\Omega$, $F$ a real Lipschitz function and $W$ a (sufficiently fast) power-decaying perturbation. Under certain conditions it is shown that $H^W_{\omega,S}$ presents quasi-ballistic dynamics for $\omega$ in a dense $G_{\delta}$ set. Applications include potentials generated by rotations of the torus with analytic condition on $F$, doubling map, Axiom A dynamical systems and the Anderson model. If $W$ is a rank one perturbation, examples of $H^W_{\omega,S}$ with quasi-ballistic dynamics and point spectrum are also presented.Comment: 17 pages; to appear in Journal of Differential Equation

Dynamical Delocalization for the 1D Bernoulli Discrete Dirac Operator

An 1D tight-binding version of the Dirac equation is considered; after checking that it recovers the usual discrete Schr?odinger equation in the nonrelativistic limit, it is found that for two-valued Bernoulli potentials the zero mass case presents absence of dynamical localization for specific values of the energy, albeit it has no continuous spectrum. For the other energy values (again excluding some very specific ones) the Bernoulli Dirac system is localized, independently of the mass.Comment: 9 pages, no figures - J. Physics A: Math. Ge

Dynamical Lower Bounds for 1D Dirac Operators

Quantum dynamical lower bounds for continuous and discrete one-dimensional Dirac operators are established in terms of transfer matrices. Then such results are applied to various models, including the Bernoulli-Dirac one and, in contrast to the discrete case, critical energies are also found for the continuous Dirac case with positive mass.Comment: 18 pages; to appear in Math.

A Link Between the Semi-Major Axis of Extrasolar Gas Giant Planets and Stellar Metallicity

The fact that most extrasolar planets found to date are orbiting metal-rich stars lends credence to the core accretion mechanism of gas giant planet formation over its competitor, the disc instability mechanism. However, the core accretion mechanism is not refined to the point of explaining orbital parameters such as their unexpected semi-major axes and eccentricities. We propose a model, which correlates the metallicity of the host star with the original semi-major axis of its most massive planet, prior to migration, considering that the core accretion scenario governs giant gas planet formation. The model predicts that the optimum regions for planetary formation shift inward as stellar metallicity decreases, providing an explanation for the observed absence of long period planets in metal-poor stars. We compare our predictions with the available data on extrasolar planets for stars with masses similar to the mass of the Sun. A fitting procedure produces an estimate of what we define as the Zero Age Planetary Orbit (ZAPO) curve as a function of the metallicity of the star. The model also hints that the lack of planets circling metal-poor stars may be partly caused by an enhanced destruction probability during the migration process, since the planets lie initially closer to the central stars.Comment: Nature of the replacement: According to recent simulations, the temperature profile, T, is more adequately reproduced by beta = 1 rather than beta = 2. We have introduced a distance scale factor that solves the very fast drop of T for low metallicity and introduces naturally the inferior distance limit of our ZAPO. Under this modification all the fitting process was altere

Periodic orbit bifurcations and scattering time delay fluctuations

We study fluctuations of the Wigner time delay for open (scattering) systems which exhibit mixed dynamics in the classical limit. It is shown that in the semiclassical limit the time delay fluctuations have a distribution that differs markedly from those which describe fully chaotic (or strongly disordered) systems: their moments have a power law dependence on a semiclassical parameter, with exponents that are rational fractions. These exponents are obtained from bifurcating periodic orbits trapped in the system. They are universal in situations where sufficiently long orbits contribute. We illustrate the influence of bifurcations on the time delay numerically using an open quantum map.Comment: 9 pages, 3 figures, contribution to QMC200

Acrocarpus fraxinifolius Wight & Arn.

Seminário realizado em Curitiba, de 6 a 8 de outubro de 1998

A Study of Single- and Double-Averaged Second-Order Models to Evaluate Third-Body Perturbation Considering Elliptic Orbits for the Perturbing Body

The equations for the variations of the Keplerian elements of the orbit of a spacecraft perturbed by a third body are developed using a single average over the motion of the spacecraft, considering an elliptic orbit for the disturbing body. A comparison is made between this approach and the more used double averaged technique, as well as with the full elliptic restricted three-body problem. the disturbing function is expanded in Legendre polynomials up to the second order in both cases. the equations of motion are obtained from the planetary equations, and several numerical simulations are made to show the evolution of the orbit of the spacecraft. Some characteristics known from the circular perturbing body are studied: circular, elliptic equatorial, and frozen orbits. Different initial eccentricities for the perturbed body are considered, since the effect of this variable is one of the goals of the present study. the results show the impact of this parameter as well as the differences between both models compared to the full elliptic restricted three-body problem. Regions below, near, and above the critical angle of the third-body perturbation are considered, as well as different altitudes for the orbit of the spacecraft.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Inst Nacl Pesquisas Espaciais, BR-12227010 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilCNPq: 150195/2012-5CNPq: 304700/2009-6FAPESP: 2011/09310-7FAPESP: 2011/08171-3Web of Scienc

Variação temporal e espacial de parâmetros de qualidade de água no reservatório de Barra Bonita/SP, como subsídio ao manejo da bacia de contribuição.

bitstream/item/135805/1/BPD-228-Qualidade-Agua.pd

Getting rid of gut microbes: surface sterilization cleans symbionts from the insects'egg masses.

Diverse heteropteran insects that feed on economic important crops, commonly known as stink bugs, are associated with specific gut symbiotic bacteria within their midgut cryptic spaces or the gastric caeca. Recent studies have revealed that the stink bugs Nezara viridula, Acrosternum hilare, Murgantia histrionica, Euschistus heros, Chlorochroa ligata, Chlorochroa sayi, Chlorochroa uhleri, Plautia stali, Thyanta pallidovirens, Dichelops melacanthus, Edessa meditabunda, Loxa deducta, Pellaea stictica, Piezodorus guildinii, Thyanta perditor, (all within Pentatomidae family) carried one major bacterium in their midgut. Phylogenetic tree generated using the 16S rRNA gene sequences obtained from the midgut of these previous species placed all symbionts in a clade with the plant-associated bacteria Erwinia and Pantoea species. In this system, females of stink bug vertically transmit the symbionts by smearing them on the surface of the egg masses. When first instars of nymphs hatch, they probe the egg surface and orally acquire the symbionts. Once ingested, these microbial symbionts will reach the 4th section of the ventriculum (V4), also known as gastric caecum, where they establish. It was hypothesized that nymphs born from surface sterilized eggs do not carry the caeca-associated symbionts. Once ingested these microbial symbionts will reach the 4th section of the ventriculum (V4), also known as gastric caecum, where they establish. It was hypothesized that nymphs born from surface sterilized eggs do not carry the caeca-associated symbionts. Herne, using scanning eletron microscopy (SEM), we are showing that surface sterilized eggs do not carry the surface microbes while eggs from the field of E. heros, D. melacanthus, N. viridula, P. stitica, and Pi. Guildinii carry them. In this unique model of transmission where the symbionts located temporally on the surface of eggs, environment factors may have a great impact on bacterial survival. Additionally, climate change may impact the insect host ecology. This information may lead to design new strategies to control the stink bugs that could used in the integrated pest management