Non-equilibrium dynamics of Andreev states in the Kondo regime

The transport properties of a quantum dot coupled to superconducting leads are analyzed. It is shown that the quasiparticle current in the Kondo regime is determined by the non-equilibrium dynamics of subgap states (Andreev states) under an applied voltage. The current at low bias is suppressed exponentially for decreasing Kondo temperature in agreement with recent experiments. We also predict novel interference effects due to multiple Landau-Zener transitions between Andreev states.Comment: Revtex4, 4 pages, 4 figure

Conductance properties of nanotubes coupled to superconducting leads: signatures of Andreev states dynamics

We present a combined experimental and theoretical analysis of the low bias conductance properties of carbon nanotubes coupled to superconducting leads. In the Kondo regime the conductance exhibits a zero bias peak which can be several times larger than the unitary limit in the normal case. This zero bias peak can be understood by analyzing the dynamics of the subgap Andreev states under an applied bias voltage. It is shown that the existence of a linear regime is linked to the presence of a finite relaxation rate within the system. The theory provides a good fitting of the experimental results.Comment: 6 revtex4 pages, 6 figures, to appear in SS

Diseño y evaluación retrospectiva de una estrategia de inversión en el mercado bursátil colombiano mediante la maximización del ratio de Sharpe

This current article represents the briefing of the results obtained by applying a optimization model developed through the use of Sharpe’s Ratio, which through a retrospective analysis simulates an investment strategy taking into account historic data of the Colombian Stock Exchange Market. From its application, annual recommended portfolios are obtained, then they are compared with the real Colombia Stock Exchange Market values (IGBC).The obtained results give evidence of the effectiveness of the formulated model in the established conditions, since their recommendations show a higher performance in the market. The contributions of this study aim at the deepening potential for other scenarios and the eventual possibility of adopting the model in real investment situations.El artículo presenta el informe de los resultados obtenidos por la aplicación de un modelo de optimización desarrollado mediante el uso del ratio de Sharpe, que en un análisis retrospectivo simula una estrategia de inversión, teniendo en cuenta los datos históricos del mercado bursátil colombiano. De su aplicación, se obtienen portafolios anuales recomendados que se comparan con los valores reales del Índice de la Bolsa de Valores de Colombia (IGBC). Los resultados alcanzados dan cuenta de la efectividad del modelo formulado en las condiciones planteadas, toda vez que sus recomendaciones demuestran un desempeño superior al del mercado. Los aportes de este estudio apuntan hacia el potencial de profundización de su análisis para otros escenarios y en la eventual posibilidad de adopción del modelo en decisiones reales de inversión

Single-channel transmission in gold one-atom contacts and chains

We induce superconductivity by proximity effect in thin layers of gold and study the number of conduction channels which contribute to the current in one-atom contacts and atomic wires. The atomic contacts and wires are fabricated with a Scanning Tunneling Microscope. The set of transmission probabilities of the conduction channels is obtained from the analysis of the $I(V)$ characteristic curve which is highly non-linear due to multiple Andreev reflections. In agreement with theoretical calculations we find that there is only one channel which is almost completely open.Comment: 4 pages, 2 figures. To be published in Phys. Rev. B, Rapid Communications (2003

Phylogenetic relationships of the Amblyomma cajennense complex (Acari: Ixodidae) at mitogenomic resolution

The genus Amblyomma is the third most diverse in the number of species within the Ixodidae, with practically half of its species distributed in the Americas, though there are also species occurring in Africa, Asia, and Australia. Within the genus, there are several species complexes with veterinary and public health importance. The Amblyomma cajennense complex, in the Americas, is represented by six species with a wide distribution, from Texas to northern Argentina. We combined two sequencing techniques to generate complete mitogenomes of species belonging to the Amblyomma cajennense complex: genome skimming and long-range PCRs sequencing methods. Thus, we generated seven new mitochondrial genomes for all species of the Amblyomma cajennense complex, except for Amblyomma interandinum. Genetic distances between the mitogenomes corroborate the clear differentiation between the five species of the Amblyomma cajennense complex. The phylogenetic relationships of these species had previously been evaluated by combining partial nuclear and mitochondrial genes and here these relationships are corroborated with a more robust framework of data, which demonstrates that the conjunction of mitochondrial and nuclear partial genes can resolve close relationships when entire genes or genomes are unavailable. The gene order, structure, composition, and length are stable across these mitogenomes, and they share the general characteristics of Metastriata. Future studies should increase the number of available mitogenomes for this genus, especially for those species from the Indo-Pacific region and Africa, by means of a better understanding of their relationships and evolutionary process.EEA RafaelaFil: Cotes-Perdomo, Andrea P. Museo Nacional de Ciencias Naturales (MNCN-CSIC), Departamento de Biodiversidad y Biología Evolutiva; EspañaFil: Cotes-Perdomo, Andrea P. University of South-Eastern. Faculty of Technology. Natural Sciences and Environmental Health Department. Natural Sciences and Maritime Sciences; NoruegaFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria. Instituto de Investigación de la Cadena Láctea (IDICAL); ArgentinaFil: Castro, Lyda R. Universidad del Magdalena. Facultad de Ciencias Básicas. Grupo de investigación Evolución, Sistemática y Ecología Molecular (GIESEMOL); ColombiaFil: Rivera-Paéz, Fredy A. Universidad de Caldas. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Biológicas. Grupo de Investigación en Genética, Biodiversidad y Manejo de Ecosistemas (GEBIOME); ColombiaFil: Cortés-Vecino, Jesús A. Universidad Nacional de Colombia. Facultad de Medicina Veterinaria y de Zootecnia. Grupo de Investigación Parasitología Veterinaria; ColombiaFil: Uribe, Juan E. Museo Nacional de Ciencias Naturales (MNCN-CSIC). Departamento de Biodiversidad y Biología Evolutiv; EspañaFil: Uribe, Juan E. Smithsonian Institution. National Museum of Natural History. Invertebrate Zoology Department; Estados Unido

Intraoperative goal directed hemodynamic therapy in noncardiac surgery: a systematic review and meta-analysis

Background: The goal directed hemodynamic therapy is an approach focused on the use of cardiac output and related parameters as end-points for fluids and drugs to optimize tissue perfusion and oxygen delivery. Primary aim: To determine the effects of intraoperative goal directed hemodynamic therapy on postoperative complications rates. Methods: A meta-analysis was carried out of the effects of goal directed hemodynamic therapy in adult noncardiac surgery on postoperative complications and mortality using Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology. A systematic search was performed in Medline PubMed, Embase, and the Cochrane Library (last update, October 2014). Inclusion criteria were randomized clinical trials in which intraoperative goal directed hemodynamic therapy was compared to conventional fluid management in noncardiac surgery. Exclusion criteria were trauma and pediatric surgery studies and that using pulmonary artery catheter. End-points were postoperative complications (primary) and mortality (secondary). Those studies that fulfilled the entry criteria were examined in full and subjected to quantifiable analysis, predefined subgroup analysis (stratified by type of monitor, therapy, and hemodynamic goal), and predefined sensitivity analysis. Results: 51 RCTs were initially identified, 24 fulfilling the inclusion criteria. 5 randomized clinical trials were added by manual search, resulting in 29 randomized clinical trials in the final analysis, including 2654 patients. A significant reduction in complications for goal directed hemodynamic therapy was observed (RR: 0.70, 95% CI: 0.62-0.79, p < 0.001). No significant decrease in mortality was achieved (RR: 0.76, 95% CI: 0.45-1.28, p = 0.30). Quality sensitive analyses confirmed the main overall results. Conclusions: Intraoperative goal directed hemodynamic therapy with minimally invasive monitoring decreases postoperative complications in noncardiac surgery, although it was not able to show a significant decrease in mortality rate

Josephson and Andreev transport through quantum dots

In this article we review the state of the art on the transport properties of quantum dot systems connected to superconducting and normal electrodes. The review is mainly focused on the theoretical achievements although a summary of the most relevant experimental results is also given. A large part of the discussion is devoted to the single level Anderson type models generalized to include superconductivity in the leads, which already contains most of the interesting physical phenomena. Particular attention is paid to the competition between pairing and Kondo correlations, the emergence of \pi-junction behavior, the interplay of Andreev and resonant tunneling, and the important role of Andreev bound states which characterized the spectral properties of most of these systems. We give technical details on the several different analytical and numerical methods which have been developed for describing these properties. We further discuss the recent theoretical efforts devoted to extend this analysis to more complex situations like multidot, multilevel or multiterminal configurations in which novel phenomena is expected to emerge. These include control of the localized spin states by a Josephson current and also the possibility of creating entangled electron pairs by means of non-local Andreev processes.Comment: 39 pages, 54 figures, corresponds to a review article as submitted to Advances in Physic

Pulmonary impairment after tuberculosis and its contribution to TB burden

<p>Abstract</p> <p>Background</p> <p>The health impacts of pulmonary impairment after tuberculosis (TB) treatment have not been included in assessments of TB burden. Therefore, previous global and national TB burden estimates do not reflect the full consequences of surviving TB. We assessed the burden of TB including pulmonary impairment after tuberculosis in Tarrant County, Texas using Disability-adjusted Life Years (DALYs).</p> <p>Methods</p> <p>TB burden was calculated for all culture-confirmed TB patients treated at Tarrant County Public Health between January 2005 and December 2006 using identical methods and life tables as the Global Burden of Disease Study. Years of life-lost were calculated as the difference between life expectancy using standardized life tables and age-at-death from TB. Years lived-with-disability were calculated from age and gender-specific TB disease incidence using published disability weights. Non-fatal health impacts of TB were divided into years lived-with-disability-acute and years lived-with-disability-chronic. Years lived-with-disability-acute was defined as TB burden resulting from illness prior to completion of treatment including the burden from treatment-related side effects. Years lived-with-disability-chronic was defined as TB burden from disability resulting from pulmonary impairment after tuberculosis.</p> <p>Results</p> <p>There were 224 TB cases in the time period, of these 177 were culture confirmed. These 177 subjects lost a total of 1189 DALYs. Of these 1189 DALYs 23% were from years of life-lost, 2% were from years lived-with-disability-acute and 75% were from years lived-with-disability-chronic.</p> <p>Conclusions</p> <p>Our findings demonstrate that the disease burden from TB is greater than previously estimated. Pulmonary impairment after tuberculosis was responsible for the majority of the burden. These data demonstrate that successful TB control efforts may reduce the health burden more than previously recognized.</p