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

Role of Disorder on the Quantum Critical Point of a Model for Heavy Fermions

A zero temperature real space renormalization group (RG) approach is used to investigate the role of disorder near the quantum critical point (QCP) of a Kondo necklace (XY-KN) model. In the pure case this approach yields $J_{c}=0$ implying that any coupling $J \not = 0$ between the local moments and the conduction electrons leads to a non-magnetic phase. We also consider an anisotropic version of the model ($X-KN$), for which there is a quantum phase transition at a finite value of the ratio between the coupling and the bandwidth, $(J/W)$. Disorder is introduced either in the on-site interactions or in the hopping terms. We find that in both cases randomness is irrelevant in the $X-KN$ model, i.e., the disorder induced magnetic-non-magnetic quantum phase transition is controlled by the same exponents of the pure case. Finally, we show the fixed point distributions $P_{J}(J/W)$ at the atractors of the disordered, non-magnetic phases.Comment: 5 pages, 3 figure

A Simple Model for the DNA Denaturation Transition

We study pairs of interacting self-avoiding walks on the 3d simple cubic lattice. They have a common origin and are allowed to overlap only at the same monomer position along the chain. The latter overlaps are indeed favored by an energetic gain. This is inspired by a model introduced long ago by Poland and Sheraga [J. Chem. Phys. {\bf 45}, 1464 (1966)] for the denaturation transition in DNA where, however, self avoidance was not fully taken into account. For both models, there exists a temperature T_m above which the entropic advantage to open up overcomes the energy gained by forming tightly bound two-stranded structures. Numerical simulations of our model indicate that the transition is of first order (the energy density is discontinuous), but the analog of the surface tension vanishes and the scaling laws near the transition point are exactly those of a second order transition with crossover exponent \phi=1. Numerical and exact analytic results show that the transition is second order in modified models where the self-avoidance is partially or completely neglected.Comment: 29 pages, LaTeX, 20 postscript figure

Large atom number dual-species magneto-optical trap for fermionic 6Li and 40K atoms

We present the design, implementation and characterization of a dual-species magneto-optical trap (MOT) for fermionic 6Li and 40K atoms with large atom numbers. The MOT simultaneously contains 5.2x10^9 6Li-atoms and 8.0x10^9 40K-atoms, which are continuously loaded by a Zeeman slower for 6Li and a 2D-MOT for 40K. The atom sources induce capture rates of 1.2x10^9 6Li-atoms/s and 1.4x10^9 40K-atoms/s. Trap losses due to light-induced interspecies collisions of ~65% were observed and could be minimized to ~10% by using low magnetic field gradients and low light powers in the repumping light of both atomic species. The described system represents the starting point for the production of a large-atom number quantum degenerate Fermi-Fermi mixture

Digital Quantum Simulation with Rydberg Atoms

We discuss in detail the implementation of an open-system quantum simulator with Rydberg states of neutral atoms held in an optical lattice. Our scheme allows one to realize both coherent as well as dissipative dynamics of complex spin models involving many-body interactions and constraints. The central building block of the simulation scheme is constituted by a mesoscopic Rydberg gate that permits the entanglement of several atoms in an efficient, robust and quick protocol. In addition, optical pumping on ancillary atoms provides the dissipative ingredient for engineering the coupling between the system and a tailored environment. As an illustration, we discuss how the simulator enables the simulation of coherent evolution of quantum spin models such as the two-dimensional Heisenberg model and Kitaev's toric code, which involves four-body spin interactions. We moreover show that in principle also the simulation of lattice fermions can be achieved. As an example for controlled dissipative dynamics, we discuss ground state cooling of frustration-free spin Hamiltonians.Comment: submitted to special issue "Quantum Information with Neutral Particles" of "Quantum Information Processing

Perfil do estado de saúde de mulheres climatéricas

Modelo do estudo: Estudo retrospectivo com análise de dados de prontuário.Objetivo: O presente estudo teve por objetivo verificar a freqüência de obesidade, diabetes mellitus,hipertensão arterial e dislipidemia em um grupo de mulheres climatéricas.Metodologia: Estudo das primeiras pacientes atendidas no Ambulatório do Climatério (ACLI) do Departamento de Ginecologia e Obstetrícia da Faculdade de Medicina de Ribeirão Preto -USP, no período de1983 a 2007. De fevereiro a abril de 2008 foram coletados dados de peso, estatura, Índice de MassaCorporal (IMC), grupo biológico, diagnóstico de hipertensão, diabetes e dislipidemia.Resultados: De 1983 a 2007, 400 pacientes tiveram seguimento no Ambulatório (ACLI), e 272 apresentavam seus prontuários com os dados do presente estudo devidamente registrados. Dessas 272pacientes, foram selecionadas 628 consultas, sendo que, portanto, em média, cada mulher teve trêsretornos. Estas mulheres tinham idade mínima de 29 e máxima de 80 anos, com IMC mediano acimade 25 kg/m2. O diagnóstico de diabetes, hipertensão e dislipidemia foi detectado em, respectivamente:32%, 68% e 54% dos casos.Conclusão: Mulheres climatéricas atendidas em um hospital de nível de atendimento terciário apresentaram um aumento do IMC e da prevalência de doenças crônicas não transmissíveis com o passar dotempo, o que faz urgir um olhar mais atento dos profissionais de saúde a esse grupo populacional.Study design: Retrospective analysis of medical records.Purpose: This study aimed to determine the prevalence of obesity, diabetes mellitus, hypertension anddyslipidemia in a group of climacteric women.Methods: Study of the first patients treated at the Menopause Clinic (ACLI), Department of Obstetrics andGynecology, School of Medicine of Ribeirão Preto (USP), from 1983 to 2007. Data on weight, height, BMI,biological group, diagnosis of hypertension, diabetes and dyslipidemia was collected from February/2008 until April/2008.Results: From 1983 until 2007, 400 patients were followed up, and 272 had their records registered. Ofthese 272 patients, 628 were selected queries, and therefore, on average, each woman had threereturns. Women over the age of 29 and maximum of 80 years and median BMI above 25kg/m². Theprevalence of diabetes, hypertension and dyslipidemia was respectively 32%, 68% and 54%. The prevalence of NCDs and BMI was higher for the later groups.Conclusion: Climacteric women treated at a hospital level care center showed a worsening of the BMIand the prevalence of noncommunicable chronic diseases over time, which is urging a closer look athealth professionals in this population group

Magnetic Field Amplification in Galaxy Clusters and its Simulation

We review the present theoretical and numerical understanding of magnetic field amplification in cosmic large-scale structure, on length scales of galaxy clusters and beyond. Structure formation drives compression and turbulence, which amplify tiny magnetic seed fields to the microGauss values that are observed in the intracluster medium. This process is intimately connected to the properties of turbulence and the microphysics of the intra-cluster medium. Additional roles are played by merger induced shocks that sweep through the intra-cluster medium and motions induced by sloshing cool cores. The accurate simulation of magnetic field amplification in clusters still poses a serious challenge for simulations of cosmological structure formation. We review the current literature on cosmological simulations that include magnetic fields and outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure

Effect of organic tomato (Lycopersicon esculentum) extract on the genotoxicity of doxorubicin in the Drosophila wing spot test

The consumption of organic tomatoes (ORTs) reduces the risk of harmful effects to humans and the environment caused by exposure to toxic agrochemicals. In this study, we used the somatic mutation and recombination test (SMART) of wing spots in Drosophila melanogaster to evaluate the genotoxicity of ORT and the effect of cotreatment with ORT on the genotoxicity of Doxorubicin® (DXR, a cancer chemotherapeutic agent) that is mediated by free radical formation. Standard (ST) cross larvae were treated chronically with solutions containing 25%, 50% or 100% of an aqueous extract of ORT, in the absence and presence of DXR (0.125 mg/mL), and the number of mutant spots on the wings of emergent flies was counted. ORT alone was not genotoxic but enhanced the toxicity of DXR when administered concomitantly with DXR. The ORT-enhanced frequency of spots induced by DXR may have resulted from the interaction of ORT with the enzymatic systems that catalyze the metabolic detoxification of this drug