Role Of Disorder In The Conduction Mechanism In Polyanilines

We present the first theoretical calculations of the electronic structure of long (200 rings) linear chains of polyaniline, ranging in composition from leucoemeraldine to emeraldine, allowing for compositional disorder in that the sequence of quinoid-benzenoid groups is random. We show that random protonation of the disordered polymers may induce p-type conductivity: This process pulls the Fermi energy down into the valence band, past localized band tails, to extended states. The effect is only seen if disorder is taken into account. © 1989 The American Physical Society.63778678

Low Density Limit of BCS Theory and Bose-Einstein Condensation of Fermion Pairs

We consider the low density limit of a Fermi gas in the BCS approximation. We show that if the interaction potential allows for a two-particle bound state, the system at zero temperature is well approximated by the Gross-Pitaevskii functional, describing a Bose-Einstein condensate of fermion pairs.Comment: LaTeX2e, 17 page

Schistosomiasis Mansoni In Urban Northeast Brazil: Influence Of Rainfall Regime On The Population Dynamics Of Biomphalaria Sp

Introduction: Our objective was to evaluate the infl uence of rainfall regime on the population dynamics of Biomphalaria in a potential urban focus of schistosomiasis in Aracaju, Brazil, during 2009-2010. Methods: Snails were collected monthly and were counted, measured and identifi ed; the level of infection and fecal contamination at the sampling sites was determined; rainfall data were obtained. Results: High levels of fecal contamination were observed, and the abundance of Biomphalaria glabrata increased during the rainy and post-rainy seasons. The snails' size was variable, and infected snails were identifi ed independently of rainfall. Conclusions: These results provide evidence of anthropogenic and climate interference in an urban focus of schistosomiasis in the Aracaju metropolitan area.465654657Pordeus, L.C., Aguiar, L.R., Quinino, L.R.M., Barbosa, C.S.A., Ocorrência das formas aguda e crônica da esquistossomose mansônica no Brasil no período de 1997 a 2006: Uma revisão de literatura (2008) Epidemiol Serv Saude, 17, pp. 163-175Souza, M.A.A., Barbosa, V.S., Wanderlei, T.N.G., Barbosa, C.S., Criadouros de Biomphalaria, temporários e permanentes, em Jaboatão dos Guararapes, PE (2008) Rev Soc Bras Med Trop, 41, pp. 252-256Araújo, K.C.G.M., Resendes, A.P.C., Souza-Santos, R., Silveira Jr., J.C., Barbosa, C.S., Análise espacial dos focos de Biomphalaria glabrata (Say, 1818) e de casos humanos de esquistossomose mansônica em Porto de Galinhas, Pernambuco, Brasil, no ano 2000 (2007) Cad Saude Publica, 23, pp. 409-417Lima, L.C., Família Planorbidae (1995) Tópicos em Malacologia Médica., pp. 90-112. , In: Barbosa FS, editor. Rio de Janeiro: Fundação Oswaldo Cruz(2005) Resolução CONAMA no 357, , http://www.cetesb.sp.gov.br/Agua/praias/res_conama_357_05.pdf, Conselho Nacional do Meio Ambiente (CONAMA). de 17 de março de. [Cited 2011 February 23]. Available fromSouza, M.A.A., Barbosa, V.S., Albuquerque, J.O., Bocanegra, S., Souza-Santos, R., Paredes, H., Aspectos ecológicos e levantamento malacológico para identificação de áreas de risco para transmissão da esquistossomose mansoni no litoral norte de Pernambuco, Brasil (2010) Iheringia Serie Zoológica, 100, pp. 19-24Barbosa, F.S., Barbosa, C.S., The bioecology of snails vectors for schistosomiasis in Brazil (1994) Cad Saude Publica, 10, pp. 200-209Fernandez, M.A., Thiengo, S.C., Susceptibility of Biomphalaria straminea from Peixe Angical dam, Tocantins, Brazil to infection with three strains of Schistosoma mansoni (2010) Mem Inst Oswaldo Cruz, 105, pp. 488-491Barbosa, C.S., Domingues, A.L.C., Abath, F., Montenegro, S.M.L., Guida, U., Carneiro, J., Epidemia de esquistossomose aguda na praia de Porto de Galinhas, Pernambuco, Brasil (2001) Cad Saude Publica, 17, pp. 725-728Rollemberg, C.V.V., Santos, C.M.B., Silva, M.M.B.L., Souza, A.M.B., Silva, A.M., Almeida, J.A.P., Aspectos epidemiológicos e distribuição geográfica da esquistossomose e geo-helmintos, no Estado de Sergipe, de acordo com os dados do Programa de Controle da Esquistossomose (2011) Rev Soc Bras Med Trop, 44, pp. 91-96Barbosa, C.S., Montenegro, S.M.L., Abath, F.G., Domingues, A.L.C., Eventos epidemiológicos relacionados à transmissão da esquistossomose em áreas rurais e urbanas de Pernambuco (2002) Mem Inst Oswaldo Cruz, 96, pp. 169-172Departamento de Vigilância Epidemiológica (2008) Vigilância e controle de moluscos de importância epidemiológica: Diretrizes técnicas., , Ministério da Saúde. Programa de Vigilância e Controle da Esquistossomose (PCE). 2nded. Brasília: Ministério da Saúd

Projecting the Bethe-Salpeter Equation onto the Light-Front and back: A Short Review

The technique of projecting the four-dimensional two-body Bethe-Salpeter equation onto the three-dimensional Light-Front hypersurface, combined with the quasi-potential approach, is briefly illustrated, by placing a particular emphasis on the relation between the projection method and the effective dynamics of the valence component of the Light-Front wave function. Some details on how to construct the Fock expansion of both i) the Light-Front effective interaction and ii) the electromagnetic current operator, satisfying the proper Ward-Takahashi identity, will be presented, addressing the relevance of the Fock content in the operators living onto the Light-Front hypersurface. Finally, the generalization of the formalism to the three-particle case will be outlined.Comment: 16 pages, macros included. Mini-review to be printed in a regular issue of Few-Body Systems devoted to the Workshop on "Relativistic Description of Two- and Three-body Systems in Nuclear Physics" ECT* Trento, 19 - 23 October 200

Superconducting fluctuations and the Nernst effect: A diagrammatic approach

We calculate the contribution of superconducting fluctuations above the critical temperature $T_c$ to the transverse thermoelectric response $\alpha_{xy}$, the quantity central to the analysis of the Nernst effect. The calculation is carried out within the microscopic picture of BCS, and to linear order in magnetic field. We find that as $T \to T_c$, the dominant contribution to $\alpha_{xy}$ arises from the Aslamazov-Larkin diagrams, and is equal to the result previously obtained from a stochastic time-dependent Ginzburg-Landau equation [Ussishkin, Sondhi, and Huse, arXiv:cond-mat/0204484]. We present an argument which establishes this correspondence for the heat current. Other microscopic contributions, which generalize the Maki-Thompson and density of states terms for the conductivity, are less divergent as $T \to T_c$.Comment: 11 pages, 5 figure

Stripes, Pseudogaps, and Van Hove Nesting in the Three-band tJ Model

Slave boson calculations have been carried out in the three-band tJ model for the high-T_c cuprates, with the inclusion of coupling to oxygen breathing mode phonons. Phonon-induced Van Hove nesting leads to a phase separation between a hole-doped domain and a (magnetic) domain near half filling, with long-range Coulomb forces limiting the separation to a nanoscopic scale. Strong correlation effects pin the Fermi level close to, but not precisely at the Van Hove singularity (VHS), which can enhance the tendency to phase separation. The resulting dispersions have been calculated, both in the uniform phases and in the phase separated regime. In the latter case, distinctly different dispersions are found for large, random domains and for regular (static) striped arrays, and a hypothetical form is presented for dynamic striped arrays. The doping dependence of the latter is found to provide an excellent description of photoemission and thermodynamic experiments on pseudogap formation in underdoped cuprates. In particular, the multiplicity of observed gaps is explained as a combination of flux phase plus charge density wave (CDW) gaps along with a superconducting gap. The largest gap is associated with VHS nesting. The apparent smooth evolution of this gap with doping masks a crossover from CDW-like effects near optimal doping to magnetic effects (flux phase) near half filling. A crossover from large Fermi surface to hole pockets with increased underdoping is found. In the weakly overdoped regime, the CDW undergoes a quantum phase transition ($T_{CDW}\to 0$), which could be obscured by phase separation.Comment: 15 pages, Latex, 18 PS figures Corrects a sign error: major changes, esp. in Sect. 3, Figs 1-4,6 replace