The MECO experiment: A search for lepton flavor violation in muonic atoms

MECO will search for direct evidence of muon and electron flavor violation in the decay of muons in Coulomb bound states via coherent recoil of the nucleus and decay electron. The expected sensitivity to the $\mu^{-} {\rm N} \to e^{-} + {\rm N}$ branching fraction relative to muon capture $\mu^{-} {\rm N}(A,Z) \to \nu_{\mu} + {\rm N}(A,Z-1)$ is $R_{\mu e} < 5\times 10^{-17}$ at 90% confidence level, roughly three to four orders of magnitude lower than current limits. This article provides an overview of the experiment.Comment: To appear in proceedings of NuFact'00 Workshop: Muon storage ring for a neutrino factory, May 22-26, 2000; Naval Postgraduate School, Monterey, C

Molecular analysis of urban rabies case from vampire bat in Corrientes, Argentina

En abril de 2006 se detectó virus de la rabia (RABV) en un gato doméstico de la ciudad de Corrientes, Argentina. La caracterización molecular identificó al murciélago Desmodus rotundus como la fuente viral. El análisis genético de 22 cepas de RABV aisladas de D. rotundus obtenidos entre 1998–2006 en Argentina, reveló la cocirculación de dos linajes genéticos en la Provincia de Corrientes. La alteración por parte del hombre, del ecosistema del murciélago en la región, podría explicar los cambios en su comportamiento y en la circulación del virus de la rabia

Disordered Electrons in a Strong Magnetic Field: Transfer Matrix Approaches to the Statistics of the Local Density of States

We present two novel approaches to establish the local density of states as an order parameter field for the Anderson transition problem. We first demonstrate for 2D quantum Hall systems the validity of conformal scaling relations which are characteristic of order parameter fields. Second we show the equivalence between the critical statistics of eigenvectors of the Hamiltonian and of the transfer matrix, respectively. Based on this equivalence we obtain the order parameter exponent $\alpha_0\approx 3.4$ for 3D quantum Hall systems.Comment: 4 pages, 3 Postscript figures, corrected scale in Fig.

Point-Contact Conductances from Density Correlations

We formulate and prove an exact relation which expresses the moments of the two-point conductance for an open disordered electron system in terms of certain density correlators of the corresponding closed system. As an application of the relation, we demonstrate that the typical two-point conductance for the Chalker-Coddington model at criticality transforms like a two-point function in conformal field theory.Comment: 4 pages, 2 figure

Substituição valvar cardíaca em ovinos – Descrição da técnica operatória e análise dos resultados

To evaluate the technical proceduresof a research protocol with tissue-engineered heartvalves in sheep, the surgical techniques for pulmonic,aortic and mitral valve replacement and the outcomeof 58 heart valve surgeries was analyzed. Thesheeps (age 18 ± 7 weeks and body weigh 30 ± 9.9kg) were implanted with valve bioprosthesis understandard protocols. Forty animals received pulmonicvalve prosthesis, fourteen animals received aorticprosthesis and four animals were implanted withmitral prosthesis. The fourth intercostal space wereconsidered the best for all operative techniques.The cardiopulmonary bypass (CPB) method throughcanulation of descending aorta and right atrial wereconsidered fast and secure. The CPB time of pulmonicvalve replacement was 34 ± 14 minutes and mortalityrate was 7,5%. The CPB time of subcoronarian aorticvalve implantation was 119 ± 5 minutes and themortality rate was 57%. In mitral substitution the CPBtime was 74 ± 22 minutes and mortality was 50%.The technique of pulmonic valve replacement wasvery efficient, however the mortality rate of both aorticand mitral valve surgery, associated with the highlysurgical technical complexity and elevated CPB time,require technical refinements to improve exploitationof the animals on the left side cardiac surgeries.Visando avaliar um protocolo experimentalde pesquisa com próteses valvares cardíacas emovinos, as técnicas cirúrgicas de substituição valvarpulmonar, aórtica e mitral de 58 cirurgias cardíacas foramanalisadas. Através de procedimentos padronizadosos ovinos (idade 18 ± 7 semanas e o peso 30 ± 9.9kg) foram submetidos ao implante de próteses valvaresbiológicas. Quarenta animais receberam prótesesvalvares pulmonares, 14 animais receberam prótesesaórticas e quatro animais receberam próteses mitrais.O quarto espaço inter-costal foi considerado de eleiçãopara realização das três técnicas operatórias avaliadas.O método de circulação extracorpórea (CPB)por canulação da aorta descendente e do átrio direitofoi considerado rápido e seguro. O tempo de CPB durantea substituição valvar pulmonar foi de 34 ± 14minutos e a mortalidade 7,5%. A substituição valvaraórtica, com implante subcoronariano, teve tempo deCPB 119 ± 5 minutos e mortalidade de 57%. Durantea substituição valvar mitral o tempo de CPB foi 74 ±22 minutos e mortalidade 50%. A técnica de implantevalvar pulmonar foi muito eficiente, entretanto a altamortalidade das técnicas de implante valvar aórtico emitral, associadas à maior complexidade cirúrgica eelevado tempo de CPB, faz necessário refinamentostécnicos para melhorar o aproveitamento dos animaisnas cirurgias das valvas cardíadas esquerdas

Phylodynamics of vampire bat-transmitted rabies in Argentina

Common vampire bat populations distributed from Mexico to Argentina are important rabies reservoir hosts in Latin America. The aim of this work was to analyse the population structure of the rabies virus (RABV) variants associated with vampire bats in the Americas and to study their phylodynamic pattern within Argentina. The phylogenetic analysis based on all available vampire bat-related N gene sequences showed both a geographical and a temporal structure. The two largest groups of RABV variants from Argentina were isolated from northwestern Argentina and from the central western zone of northeastern Argentina, corresponding to livestock areas with different climatic, topographic and biogeographical conditions, which determined their dissemination and evolutionary patterns. In addition, multiple introductions of the infection into Argentina, possibly from Brazil, were detected. The phylodynamic analysis suggests that RABV transmission dynamics is characterized by initial epizootic waves followed by local enzootic cycles with variable persistence. Anthropogenic interventions in the ecosystem should be assessed taking into account not only the environmental impact but also the potential risk of disease spreading through dissemination of current RABV lineages or the emergence of novel ones associated with vampire bats.Fil: Torres, Carolina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lema, C.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud; ArgentinaFil: Gury Dohmen, F.. Instituto de Zoonosis “Dr. Luis Pasteur”; ArgentinaFil: Beltran, F.. Instituto de Zoonosis “Dr. Luis Pasteur”; ArgentinaFil: Novaro, L.. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; ArgentinaFil: Russo, S.. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; ArgentinaFil: Freire, M. C.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud; ArgentinaFil: Velasco Villa, A.. Centers for Disease Control and Prevention; Estados UnidosFil: Mbayed, Viviana Andrea. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cisterna , D. M.. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; Argentin

Survey Evidence on Conditional Norm Enforcement

We discuss survey evidence on individuals' willingness to sanction norm violations - such as evading taxes, drunk driving, fare dodging, or skiving o work - by expressing disapproval or social exclusion. Our data suggest that people condition their sanctioning behavior on their belief about the frequency of norm violations. The more commonly a norm violation is believed to occur, the lower the individuals' inclination to punish it. Based on an instrumental variable approach, we demonstrate that this pattern reflects a causal relationship