Bosonization Approach For Bilayer Quantum Hall Systems At νt=1

We develop a nonperturbative bosonization approach for bilayer quantum Hall systems at νT=1, which allows us to systematically study the existence of an exciton condensate in these systems. An effective boson model is derived and the excitation spectrum is calculated in both the Bogoliubov and the Popov approximations. In the latter case, we show that the ground state of the system is an exciton condensate only when the distance between the layers is very small compared to the magnetic length, indicating that the system possibly undergoes another phase transition before the incompressible-compressible one. The effect of a finite electron interlayer tunneling is included and a quantitative phase diagram is proposed. © 2006 The American Physical Society.9718(1997) Perspectives in Quantum Hall Effects, , edited by S. Das Sarma and A. Pinczuk (Wiley, New York)Eisenstein, J.P., MacDonald, A.H., (2004) Nature (London), 432, p. 691. , NATUAS 0028-0836 10.1038/nature03081Eisenstein, J.P., (2004) Science, 305, p. 950. , SCIEAS 0036-8075 10.1126/science.1099386Murphy, S.Q., (1994) Phys. Rev. Lett., 72, p. 728. , PRLTAO 0031-9007 10.1103/PhysRevLett.72.728Girvin, S.M., cond-mat/0108181Spielman, I.B., (2000) Phys. Rev. Lett., 84, p. 5808. , PRLTAO 0031-9007 10.1103/PhysRevLett.84.5808Spielman, I.B., (2001) Phys. Rev. Lett., 87, p. 036803. , PRLTAO 0031-9007 10.1103/PhysRevLett.87.036803Fertig, H.A., Straley, J.P., (2003) Phys. Rev. Lett., 91, p. 046806. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.046806Kellogg, M., (2004) Phys. Rev. Lett., 93, p. 036801. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.036801Wiersma, R.D., (2004) Phys. Rev. Lett., 93, p. 266805. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.266805Wen, X.G., Zee, A., (1992) Phys. Rev. Lett., 69, p. 1811. , PRLTAO 0031-9007 10.1103/PhysRevLett.69.1811Fertig, H.A., (1989) Phys. Rev. B, 40, p. 1087. , PRBMDO 0163-1829 10.1103/PhysRevB.40.1087MacDonald, A.H., (1990) Phys. Rev. Lett., 65, p. 775. , PRLTAO 0031-9007 10.1103/PhysRevLett.65.775Joglekar, Y.N., MacDonald, A.H., (2001) Phys. Rev. B, 64, p. 155315. , PRBMDO 0163-1829 10.1103/PhysRevB.64.155315Fertig, H.A., Murthy, G., (2005) Phys. Rev. Lett., 95, p. 156802. , PRLTAO 0031-9007 10.1103/PhysRevLett.95.156802Doretto, R.L., Caldeira, A.O., Girvin, S.M., (2005) Phys. Rev. B, 71, p. 045339. , PRBMDO 0163-1829 10.1103/PhysRevB.71.045339Kallin, C., Halperin, B.I., (1984) Phys. Rev. B, 30, p. 5655. , PRBMDO 0163-1829 10.1103/PhysRevB.30.5655Fetter, A.L., Walecka, J.D., (2003) Quantum Theory of Many-Particle Systems, , Dover, MineolaStoof, H.T.C., Bijlsma, M., (1993) Phys. Rev. E, 47, p. 939. , PLEEE8 1063-651X 10.1103/PhysRevE.47.939Shi, H., Griffin, A., (1998) Phys. Rep., 304, p. 1. , PRPLCM 0370-1573 10.1016/S0370-1573(98)00015-5Chen, X.M., Quinn, J.J., (1992) Phys. Rev. B, 45, p. 11054. , PRBMDO 0163-1829 10.1103/PhysRevB.45.1105

Genome-wide identification, characterization and expression profiling of the ubiquitin-proteasome genes in biomphalaria glabrata

Biomphalaria glabrata is the major species used for the study of schistosomiasis-related parasite-host relationships, and understanding its gene regulation may aid in this endeavor. The ubiquitin-proteasome system (UPS) performs post-translational regulation in order to maintain cellular protein homeostasis and is related to several mechanisms, including immune responses. The aims of this work were to identify and characterize the putative genes and proteins involved in UPS using bioinformatic tools and also their expression on different tissues of B. glabrata. The putative genes and proteins of UPS in B. glabrata were predicted using BLASTp and as queries reference proteins from model organism. We characterized these putative proteins using PFAM and CDD software describing the conserved domains and active sites. The phylogenetic analysis was performed using ClustalX2 and MEGA5.2. Expression evaluation was performed from 12 snail tissues using RPKM. 119 sequences involved in the UPS in B. glabrata were identified, which 86 have been related to the ubiquitination pathway and 33 to proteasome. In addition, the conserved domains found were associated with the ubiquitin family, UQ_con, HECT, U-box and proteasome. The main active sites were lysine and cysteine residues. Lysines are responsible and the starting point for the formation of polyubiquitin chains, while the cysteine residues of the enzymes are responsible for binding to ubiquitin. The phylogenetic analysis showed an organized distribution between the organisms and the clades of the sequences, corresponding to the tree of life of the animals, for all groups of sequences analyzed. The ubiquitin sequence was the only one with a high expression profile found in all libraries, inferring its wide range of performance. Our results show the presence, conservation and expression profile of the UPS in this mollusk, providing a basis and new knowledge for other studies involving this system. Due to the importance of the UPS and B. glabrata, this work may influence the search for new methodologies for the control of schistosomiasis114CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ479890/2013-

Self-consistent quantal treatment of decay rates within the perturbed static path approximation

The framework of the Perturbed Static Path Approximation (PSPA) is used to calculate the partition function of a finite Fermi system from a Hamiltonian with a separable two body interaction. Therein, the collective degree of freedom is introduced in self-consistent fashion through a Hubbard-Stratonovich transformation. In this way all transport coefficients which dominate the decay of a meta-stable system are defined and calculated microscopically. Otherwise the same formalism is applied as in the Caldeira-Leggett model to deduce the decay rate from the free energy above the so called crossover temperature $T_0$.Comment: 17 pages, LaTex, no figures; final version, accepted for publication in PRE; e-mail: [email protected]

Generalized quantum Fokker-Planck, diffusion and Smoluchowski equations with true probability distribution functions

Traditionally, the quantum Brownian motion is described by Fokker-Planck or diffusion equations in terms of quasi-probability distribution functions, e.g., Wigner functions. These often become singular or negative in the full quantum regime. In this paper a simple approach to non-Markovian theory of quantum Brownian motion using {\it true probability distribution functions} is presented. Based on an initial coherent state representation of the bath oscillators and an equilibrium canonical distribution of the quantum mechanical mean values of their co-ordinates and momenta we derive a generalized quantum Langevin equation in $c$-numbers and show that the latter is amenable to a theoretical analysis in terms of the classical theory of non-Markovian dynamics. The corresponding Fokker-Planck, diffusion and the Smoluchowski equations are the {\it exact} quantum analogues of their classical counterparts. The present work is {\it independent} of path integral techniques. The theory as developed here is a natural extension of its classical version and is valid for arbitrary temperature and friction (Smoluchowski equation being considered in the overdamped limit).Comment: RevTex, 16 pages, 7 figures, To appear in Physical Review E (minor revision

Quantum Fluctuation Relations for the Lindblad Master Equation

An open quantum system interacting with its environment can be modeled under suitable assumptions as a Markov process, described by a Lindblad master equation. In this work, we derive a general set of fluctuation relations for systems governed by a Lindblad equation. These identities provide quantum versions of Jarzynski-Hatano-Sasa and Crooks relations. In the linear response regime, these fluctuation relations yield a fluctuation-dissipation theorem (FDT) valid for a stationary state arbitrarily far from equilibrium. For a closed system, this FDT reduces to the celebrated Callen-Welton-Kubo formula

Stochastic thermodynamics of holonomic systems

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Whole genome analysis of a schistosomiasis-transmitting freshwater snail

Biomphalaria snails are instrumental in transmission of the human blood fluke Schistosoma mansoni. With the World Health Organization's goal to eliminate schistosomiasis as a global health problem by 2025, there is now renewed emphasis on snail control. Here, we characterize the genome of Biomphalaria glabrata, a lophotrochozoan protostome, and provide timely and important information on snail biology. We describe aspects of phero-perception, stress responses, immune function and regulation of gene expression that support the persistence of B. glabrata in the field and may define this species as a suitable snail host for S. mansoni. We identify several potential targets for developing novel control measures aimed at reducing snail-mediated transmission of schistosomiasis