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

Universal quantum signature of mixed dynamics in antidot lattices

We investigate phase coherent ballistic transport through antidot lattices in the generic case where the classical phase space has both regular and chaotic components. It is shown that the conductivity fluctuations have a non-Gaussian distribution, and that their moments have a power-law dependence on a semiclassical parameter, with fractional exponents. These exponents are obtained from bifurcating periodic orbits in the semiclassical approximation. They are universal in situations where sufficiently long orbits contribute.Comment: 7 page

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

The renal and hepatic distribution of Bence Jones proteins depends on glycosylation: A scintigraphic study in rats

The aim of the present study was to evaluate renal and liver distribution of two monoclonal immunoglobulin light chains. the chains were purified individually from the urine of patients with multiple myeloma and characterized as lambda light chains with a molecular mass of 28 kDa. They were named BJg (high amount of galactose residues exposed) and BJs (sialic acid residues exposed) on the basis of carbohydrate content. A scintigraphic study was performed on male Wistar rats weighing 250 g for 60 min after iv administration of 1 mg of each protein (7.4 MBq), as the intact proteins and also after carbohydrate oxidation. Images were obtained with a Siemens gamma camera with a high-resolution collimator and processed with a MicroDelta system. Hepatic and renal distribution were established and are reported as percent of injected dose. Liver uptake of BJg was significantly higher than liver uptake of BJs (94.3 vs 81.4%) (P<0.05). This contributed to its greater removal from the intravascular compartment, and consequently lower kidney accumulation of BJg in comparison to BJs (5.7 vs 18.6%) (P<0.05). After carbohydrate oxidation, there was a decrease in hepatic accumulation of both proteins and consequently a higher renal overload. the tissue distribution of periodate-treated BJg was similar to that of native BJs: 82.7 vs 81.4% in the liver and 17.3 vs 18.6% in the kidneys. These observations indicate the important role of sugar residues of Bence Jones proteins for their recognition by specific membrane receptors, which leads to differential tissue accumulation and possible toxicity.UNIV São Paulo,FAC MED,LAB FISIOPATOL RENAL,BR-01246903 São Paulo,SP,BRAZILUNIV São Paulo,CTR MED NUCL,BR-05403010 São Paulo,SP,BRAZILUNIV São Paulo,HOSP CLIN,SERV RADISISOTOPOS,BR-05403000 São Paulo,SP,BRAZILUniversidade Federal de São Paulo,MOL BIOL LAB,BR-04024900 São Paulo,SP,BRAZILUniversidade Federal de São Paulo,MOL BIOL LAB,BR-04024900 São Paulo,SP,BRAZILWeb of Scienc

Superscars in the LiNC=LiCN isomerization reaction

We demonstrate the existence of superscarring in the LiNC=LiCN isomerization reaction described by a realistic potential interaction in the range of readily attainable experimental energies. This phenomenon arises as the effect of two periodic orbits appearing "out of the blue"in a saddle--node bifurcation taking place in the dynamics of the system. Potential practical consequences of this superlocalization in the corresponding wave functions are also considered.Comment: 6 pages, 5 figures. to appear in EP

Optimal transfers from Moon to L2L_2 halo orbit of the Earth-Moon system

In this paper, we seek optimal solutions for a transfer from a parking orbit around the Moon to a halo orbit around $L_2$ of the Earth-Moon system, by applying a single maneuver and exploiting the stable invariant manifold of the hyperbolic parking solution at arrival. For that, we propose an optimization problem considering as variables both the orbital characteristics of a parking solution around the Moon, (namely, its Keplerian elements) and the characteristics of a transfer trajectory guided by the stable manifold of the arrival Halo orbit. The problem is solved by a nonlinear programming method (NLP), aiming to minimize the cost of $\Delta V$ to perform a single maneuver transfer, within the framework of the Earth-Moon system of the circular restricted three-body problem. Results with low $\Delta V$ and suitable time of flight show the feasibility of this kind of transfer for a Cubesat

Ants (Hymenoptera, Formicidae) of APA Pandeiros: A Perspective from a Decade of Research in an Environmental Protection Area in the Cerrado-Caatinga Transition

Habitat transformation and species loss bring enormous environmental damage, whereas establishing protected areas promotes more sustainable use of environmental resources through biodiversity conservation. In this study, we aimed to point out gaps in ant knowledge and provide a species checklist that contributes to biodiversity conservation in the transition areas between Cerrado and Caatinga biomes, constantly threatened by land use changes. This checklist integrates data from previous studies developed at “Área de Proteção Ambiental do Rio Pandeiros” (APA Pandeiros), Minas Gerais, Brazil, involving ant diversity and their contribution to ecological processes accessed and described in the studies. We showed and discussed how authors managed and provided information regarding methodologies and habitats sampled. We listed 143 ant species formally named. Pheidole, Camponotus and Cephalotes were the most speciose genera, with more than ten species each. Among ants involved in ecological processes, 40 are linked to diaspore removal (part of seed dispersal) and 30 to carcass interaction (part of the decomposition process). Unbaited pitfall traps, epigeic stratum and Cerrado sensu stricto, were the top sampling method, stratum, and habitats among ant studies. We presented proposals for the best management and integration of data from surveys in APA Pandeiros (e.g., sharing the results of the studies with the APA managers, creating a database, and the local community). These surveys are fundamental for understanding biodiversity and ecological processes and provide valuable information to conservation biology. Therefore, neglecting the importance of the Cerrado-Caatinga transition can lead to irreparable setbacks for scientific knowledge and biodiversity

Numerical investigations of the orbital dynamics around a synchronous binary system of asteroids

In this article, equilibrium points and families of periodic orbits in the vicinity of the collinear equilibrium points of a binary asteroid system are investigated with respect to the angular velocity of the secondary body, the mass ratio of the system and the size of the secondary. We assume that the gravitational fields of the bodies are modeled assuming the primary as a mass point and the secondary as a rotating mass dipole. This model allows to compute families of planar and halo periodic orbits that emanate from the equilibrium points $L_1$ and $L_2$. The stability and bifurcations of these families are analyzed and the results are compared with the results obtained with the Restricted Three-Body Problem (RTBP). The results provide an overview of the dynamical behavior in the vicinity of a binary asteroid system