The non-twist standard map with robust tori

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Robust tori in a double-waved Hamiltonian model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Robust tori-like Lagrangian coherent structures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Labyrinthic standard non-twist map

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of robust torus on the dynamical transport

In the present work, we quantify the fraction of trajectories that reach a specific region of the phase space when we vary a control parameter using two symplectic maps: one non-twist and another one twist. The two maps were studied with and without a robust torus. We compare the obtained patterns and we identify the effect of the robust torus on the dynamical transport. We show that the effect of meandering-like barriers loses importance in blocking the radial transport when the robust torus is present.

Blocking Radial Diffusion in a Double-Waved Hamiltonian Model

A non-twist Hamiltonian system perturbed by two waves with particular wave numbers can present Robust Tori, barriers created by the vanishing of the perturbing Hamiltonian at some defined positions. When Robust Tori exist, any trajectory in phase space passing close to them is blocked by emergent invariant curves that prevent the chaotic transport. We analyze the breaking up of the RT as well the transport dependence on the wave numbers and on the wave amplitudes. Moreover, we report the chaotic web formation in the phase space and how this pattern influences the transport.

Magnetic Field Line Escape: Comparison with Mean Free Path

In the present work, we determine the fraction of magnetic field lines that reach the tokamak wall leaving the plasma surrounded by a chaotic layer created by resonant perturbations at the plasma edge. The chaotic layer arises in a scenario where an integrable magnetic field with reversed magnetic shear is perturbed by an ergodic magnetic limiter. For each considered line, we calculate its connection length, i.e. the number of toroidal turns that the field lines complete before reaching the wall. We represent the results in the poloidal section in which the initial coordinates are chosen. We also estimate the radial profile of the fraction of field lines, for different temperatures, whose connection lengths are smaller than the electron collisional mean free path.

Decay of energy and suppression of Fermi acceleration in a dissipative driven stadium-like billiard

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Stickiness in a bouncer model: A slowing mechanism for Fermi acceleration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A combined method for evaluating radon and progeny in waters and its use at Guarani aquifer, São Paulo State, Brazil

A combined method for evaluating radon (Rn-222) and progeny (Pb-214 and Bi-214) in water was developed by using inexpensive alpha scintillation Counting and gamma ray spectrometry through NaI(Tl) scintillation detectors. A groundwater sample collected at the Pocos de Caldas alkaline massif in Brazil was submitted to the technique in order to assure its applicability by comparing the volumetric activities by different methods. Similar volumetric activity was determined for Pb-214 and Bi-214 in the sample analyzed that is compatible with the expected condition of radioactive equilibrium between these nuclides. The combined method was successfully used to analyze groundwater samples from Guarani aquifer in S (a) over tildeo Paulo State, Brazil, and the results of the measurements indicated that Pb-214 and Bi-214 provide useful information concerning the evaluation of the drinking water quality in terms of radiological aspects. This is because they are directly identified in the water samples, without the need of requiring the assumption of the establishment of the transient equilibrium condition with its parent Rn-222. (c) 2005 Elsevier Ltd. All rights reserved.

Implications of groundwater weathered profile interactions to the mobilization of radionuclides

This study reports the nature and extent of open-system interaction between groundwater and a weathered profile developed in the high grade thorium and REE ore body in Morro do Ferro, Pocos de Caldas plateau. The radioelement mobility in the shallow oxidizing environment was considered by using chemical data in conjunction with U-234/U-238, Ra-226/Th-230, Th-230/U-234, Th-228/Th-232, Ra-228/Th-232 and Th-230/Ra-228 activity ratios (AR's) for borehole spoil and groundwater samples.Recharging groundwater from the studied borehole has low salinity values, with total dissolved solids content of 14.7 mg/l and total ionic strength of 0.00018. The ratio of the weight of dissolved radioelement per unit volume of solution to the weight of radioelement in solid phase per unit weight of solid phase showed that the radioelement solubility in the studied waters varied according to the following order: radium> uranium >thorium.U-234/U-238 AR's less than 1 were measured in solid phase and can justify the enhancement of U-234 in solution. Ra-226/Th-230 AR's greater than 1 and Th-230/U-234 AR'S less than 1 were evaluated between 20 and 27 m in depth, where a 2.1-m thick magnetite dike was intersected. These ratios could be justified by deposition of U and Ra associated with Fe-Mn oxides and kaolinite, where mineral saturation indices evaluated from the available data confirm this possibility. Covariations among disequilibria involving Th-228/(228) Ra and Ra-228/Th-232 AR's showed the preferential removal of Ra-228 relative to Tn isotopes, Th-228 and Th-232. The recent deposition of radium within the timescale of at least the last 35 years also is suggested. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

Differential proteomic analysis of Acidithiobacillus ferrooxidans cells maintained in contact with bornite or chalcopyrite: Proteins involved with the early bacterial response

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Direct and Simultaneous Determination of Cd Cu, and Se in Blood Samples by Graphite Furnace Atomic Absorption Spectrometry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Simultaneous Determination of Ba, Cr, Mo (Group 1), and Cu, Fe, Ni, and Pb (Group 2) in Commercial Fuel Ethanol by Graphite Furnace AAS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of modifiers for As, Cu and Pb determinations in sugar-cane spirits by GF AAS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)