Partial hyperbolicity for symplectic diffeomorphisms

We prove that every robustly transitive and every stably ergodic symplectic diffeomorphism on a compact manifold admits a dominated splitting. In fact, these diffeomorphisms are partially hyperbolic. (c) 2005 Elsevier SAS. All rights reserved.

Genetic diversity and population structure of pumas (Puma concolor) in southeastern Brazil: implications for conservation in a human-dominated landscape

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A bounded upwinding scheme for computing convection-dominated transport problems

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Non-Zeeman splitting for a spin-resolved STM with a Kondo adatom in a spin-polarized two-dimensional electron gas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Grass-dominated stream sites exhibit low fish species diversity and dominance by guppies: an assessment of two tropical pasture river basins

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Upper-mantle seismic anisotropy from SKS splitting in the South American stable platform: A test of asthenospheric flow models beneath the lithosphere

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stream fish, water and habitat quality in a pasture dominated basin, southeastern Brazil

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Supramolecular assemblies of cis-palladium complexes dominated by C-H center dot center dot center dot Cl interactions

Two cis-related palladium(II) complexes [PdCl(2)(PPh(3))(tu)] (1) and [PdCl(2)(tmen)] (2) {PPh(3) = triphenylphosphine, tu = thiourea, tmen = N,N,N,N-tetramethylethylenediamine} have been synthesized and characterized by elemental analysis, IR and NMR spectroscopies, and single crystal X-ray diffraction. In 1, N-H center dot center dot center dot Cl hydrogen bonds are responsible for the formation of a dimer which connects to an adjacent one through weak C-H center dot center dot center dot Cl interactions, yielding 1D tapes. The crystal packing of compound 2 consists of zigzag ribbons of [PdCl(2)(tmen)] self-assembled by C-H center dot center dot center dot Cl hydrogen bonds which also holds the chains together, giving rise to a 2D layered structure. (C) 2006 Elsevier B.V. All rights reserved.

Macrobenthic intertidal communities from wave to tide dominated beach environments. A case study in two Brazilian beaches

Modification showed by intertidal macrofaunal communities between two nearby sites that change from a wave to a tide dominated beach environment, was analyzed on the present study. At each site, eleven intertidal sampling stations were distributed along a transect, from the drift line to the spring low tide water level. Four macrofaunal samples one meter long-shore spaced were collected at, each station with an iron core of 0.05 m(2) surface area, taken to a depth of 20 cm. Major,differences on sediments between sites were the offshore decrease of mean particle size diameter and increase of kurtosis and water content at the tide dominated site. KIDS ordination showed major similarities between the lowest stations of this site, that represents the dissipative low tide-terrace portion of the beach. Two lower station of the wave dominated site presented similarities with this group. The other stations of the tide-dominated site, that represents the reflective high tide beach portion, grouped distant from the former. (canonical Correspondence Analysis (CCA) showed a similar spatial distribution of stations, suggesting the importance of environmental factors on the explanation of species distribution patterns. Sediment water content and water table depth, with the highest inertia value, seems to be the principal physical factor. Increase on water content affects the macrofaunal distribution by the expansion of typical infralitoral species, as was the case of Bathyporeiapus ruffoi, on the dissipative low tide terrace beach portion. A disrupted distribution with the lost of a gradate zonation along a physical gradient is one of the major modification presented by macrobenthic communities on the transition from a wave to a tide dominated beach environment.

Hyolith-dominated shell beds from the Lampazar Formation in NW Argentina: patterns and processes of origin in the Late Cambrian (Furongian) seas of western Gondwana.

Late Cambrian (Furongian) shell beds in the Salta Province of NW Argentina are unique because of the presence of abundant hyolith skeletal remains within them. Hyolith shell beds are located in the mid-upper part of the Lampazar Formation at the Angosto de La Quesera locality, and are the first recorded accumulations of this type in the lower Palaeozoic of the South American Andean Basin. The shell beds are of the order of several mm thick, and are laterally persistent within outcrop scale, with a few metres of lateral development. Two types of hyolith shell beds are recognised: Type 1 is a storm-dominated, event concentration, represented by dispersed to densely packed accumulations of well preserved hyolith and gastropod shells (Strepsodiscus austrinus). Hyolith conchs are current oriented with the long axes parallel to unidirectional flow on the sandstones surfaces. Type 2 shell beds are background, composite concentrations, of poorly preserved, comminuted debris of hyolith shells with associated gastropod and trilobite sclerites (dominated by Parabolina, Beltella and Leiostegium). The genesis of both shell beds was controlled primarily by physical processes, such as storms and current and/or wave agitation. The thickness, simple internal fabric and geometry shown by both accumulations are typical of Cambrian-style shell-beds.

Macroscopic quantum tunneling in a dc SQUID: Instanton splitting

The theory of macroscopic quantum tunneling is applied to a current-biased dc SQUID which constitutes a system of two interacting quantum degrees of freedom coupled to the environment. The decay probability is obtained in the exponential approximation for the overdamped case. Close to the critical driving force of the system, the decay of the metastable state is determined by a unique instanton solution describing the symmetric decay of the phases in each of the two Josephson juctions. Upon reducing the external driving force a new regime is reached where the instanton splits. The doubling of the decay channels reduces the decreasing of the decay rate in the quantum regime. A current-temperature phase diagram is constructed based on the Landau theory of phase transitions. Depending on the external parameters the system develops either a first- or a second-order transition to the split-instanton regime. © 1994 The American Physical Society.

Note on the point-splitting procedure to evaluate vacuum fluctuation in certain cylindrically symmetric backgrounds

We reexamine the two-point function approaches used to study vacuum fluctuation in wedge-shaped regions and conical backgrounds. The appearance of divergent integrals is discussed and circumvented. The issue is considered in the context of a massless scalar field in cosmic string spacetime.

Effect of the Rashba and Dresselhaus spin-splitting terms on the electron g factor in semiconductor quantum wells under applied magnetic fields

We use the Ogg-McCombe Hamiltonian together with the Dresselhaus and Rashba spin-splitting terms to find the g factor of conduction electrons in GaAs-(Ga,Al)As semiconductor quantum wells (QWS) (either symmetric or asymmetric) under a magnetic field applied along the growth direction. The combined effects of non-parabolicity, anisotropy and spin-splitting terms are taken into account. Theoretical results are given as functions of the QW width and compared with available experimental data and previous theoretical works. © 2007 Elsevier B.V. All rights reserved.

Cervicovaginal Levels of Proinflammatory Cytokines Are Increased During Chlamydial Infection in Bacterial Vaginosis But Not in Lactobacilli-Dominated Flora

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