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Penate-Rodriguez H.C.,Instituto Superior Of Tecnologia Y Ciencias Aplicadas | Penate-Rodriguez H.C.,Institute Fisica Fundamental Csic | Bargueno P.,Complutense University of Madrid | Miret-Artes S.,Institute Fisica Fundamental Csic
Chemical Physics Letters | Year: 2012

Geometric phases within a canonical formulation of chiral molecules are analyzed paying special attention to the fundamental role played by the parity violating energy difference. We study the Hamiltonian dynamics in terms of canonically conjugate variables, showing how parity-violating energy difference could be locked (PVED-locking) by means of a circularly polarized electric field. Signatures of this locking are predicted to occur both in the geometric phase and in the interference between chiral states. © 2011 Elsevier B.V. All rights reserved. Source


Penate-Rodriguez H.C.,Instituto Superior Of Tecnologia Y Ciencias Aplicadas | Penate-Rodriguez H.C.,Institute Fisica Fundamental Csic | Dorta-Urra A.,CSIC Institute Fisica Fundamental CSIC | Bargueno P.,Complutense University of Madrid | And 3 more authors.
Chirality | Year: 2013

A canonical framework for chiral two-level systems coupled to a bath of harmonic oscillators is developed to extract, from a stochastic dynamics, the thermodynamic equilibrium values of both the population difference and coherences. The incoherent and coherent tunneling regimes are analyzed for an Ohmic environment in terms of a critical temperature defined by the maximum of the heat capacity. The corresponding numerical results issued from solving a non-linear coupled system of equations are fitted to approximate path-integral analytical expressions beyond the so-called non-interacting blip approximation in order to determine the different time scales governing both regimes. © 2013 Wiley Periodicals, Inc. © 2013 Wiley Periodicals, Inc. Source


Maidana N.L.,University of Sao Paulo | Vanin V.R.,University of Sao Paulo | Garcia-Alvarez J.A.,University of Sao Paulo | Garcia-Alvarez J.A.,Instituto Superior Of Tecnologia Y Ciencias Aplicadas | And 3 more authors.
Applied Radiation and Isotopes | Year: 2016

The peak efficiency for photons hitting the frontal surface of a medium volume n-type HPGe coaxial detector is mapped using acutely collimated beams of energies between 31 and 383keV from a 133Ba radioactive source. Simulated values obtained with the Monte Carlo radiation transport code penelope, using a model that respected actual detector dimensions and physical constants while varying dead-layer thicknesses, allowed us to fit the experimental results in the detector bulk but not near its rim. The spectra of a 137Cs source were measured using the detector shielded from the natural background radiation, with and without a broad angle collimator. The corresponding simulated spectra, using the fitted dead-layer thicknesses, underestimate the continuum component of the spectra and overestimate the peak efficiency, by less than ten percent in the broad angle collimator arrangement. The simulated results are sensitive to the photon attenuation coefficients. © 2015. Source


Dorta-Urra A.,Institute Fisica Fundamental | Peate-Rodriguez H.C.,Instituto Superior Of Tecnologia Y Ciencias Aplicadas | Peate-Rodriguez H.C.,Institute Fisica Fundamental | Bargueo P.,Complutense University of Madrid | And 3 more authors.
Journal of Chemical Physics | Year: 2012

Within a generalized Langevin framework for open quantum systems, the cyclic evolution of a two-level system is analyzed in terms of the geometric phase extended to dissipative systems for Ohmic friction. This proposal is applied to the dynamics of chiral molecules where the tunneling and parity violating effects are competing. The effect of different system-bath coupling functions in the dissipated energy is shown to be crucial to understand the behavior of the geometric phase as well as the decoherence displayed by the corresponding interference patterns. © 2012 American Institute of Physics. Source


Arruda-Neto J.D.T.,University of Sao Paulo | Geraldo L.P.,Catholic University of Santos | Prado G.R.,University of Sao Paulo | Garcia F.,State University of Santa Cruz | And 7 more authors.
Environment International | Year: 2010

We investigated chronic incorporation of metals in individuals from poor families, living in a small, restrict and allegedly contaminated area in São Paulo city, the surroundings of the Guarapiranga dam, responsible for water supply to 25% of the city population. A total of 59 teeth from individuals 7 to 60 years old were collected. The average concentrations of Pb, Cd, Fe, Zn, Mn, Ni and Cr were determined with an Atomic Absorption Spectrophotometer. The concentrations of all metals as function of the individuals' age exhibited a remarkable similarity: peaks between 7 and 10 years and sharply decreasing at higher ages, which could be attributed to alimentary habits and persistence to metals exposure all along the individuals' life span. From all the measured metals, lead and cadmium were a matter of much more concern since their measured values are close to the upper limits of the world wide averages. © 2009 Elsevier Ltd. All rights reserved. Source

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