Non-equilibrium transition from dissipative quantum walk to classical random walk

We have investigated the time-evolution of a free particle in interaction with a phonon thermal bath, using the tight-binding approach. A dissipative quantum walk can be defined and many important non-equilibrium decoherence properties can be investigated analytically. The non-equilibrium statistics of a pure initial state have been studied. Our theoretical results indicate that the evolving wave-packet shows the suppression of Anderson's boundaries (ballistic peaks) by the presence of dissipation. Many important relaxation properties can be studied quantitatively, such as von Neumann's entropy and quantum purity. In addition, we have studied Wigner's function. The time-dependent behavior of the quantum entanglement between a free particle -in the lattice- and the phonon bath has been characterized analytically. This result strongly suggests the non-trivial time-dependence of the off-diagonal elements of the reduced density matrix of the system. We have established a connection between the quantum decoherence and the dissipative parameter arising from interaction with the phonon bath. The time-dependent behavior of quantum correlations has also been pointed out, showing continuous transition from quantum random walk to classical random walk, when dissipation increases.Comment: Submitted for publication. 17 pages, 6 figure

Functional characterization of generalized Langevin equations

We present an exact functional formalism to deal with linear Langevin equations with arbitrary memory kernels and driven by any noise structure characterized through its characteristic functional. No others hypothesis are assumed over the noise, neither the fluctuation dissipation theorem. We found that the characteristic functional of the linear process can be expressed in terms of noise's functional and the Green function of the deterministic (memory-like) dissipative dynamics. This object allow us to get a procedure to calculate all the Kolmogorov hierarchy of the non-Markov process. As examples we have characterized through the 1-time probability a noise-induced interplay between the dissipative dynamics and the structure of different noises. Conditions that lead to non-Gaussian statistics and distributions with long tails are analyzed. The introduction of arbitrary fluctuations in fractional Langevin equations have also been pointed out

Indirect genetic effects on the relationships between production and feeding behaviour traits in growing Duroc pigs

Performance and feeding behaviour traits in growing pigs could be affected by social interaction effects when animals are raised in group. So, properly knowing the genetic correlations between direct and social interaction effects among performance and feeding behaviour traits could improve the accuracy of the genetic evaluations. Our aim was to explore the role of feeding behaviour traits (FBT) and indirect genetic effects (IGEs) in the genetic evaluations of growing pigs. Thus, genetic parameters were estimated for production traits (PT): average daily gain, average daily feed consumption, feed conversion ratio and backfat thickness; as well as for FBT: average daily feeding rate, average daily feeding frequency, average daily occupation time and average daily time between consecutive visits. Traits were recorded in 1144 Duroc pigs during the fattening period. Two bivariate models were fitted: classic animal model and an animal model fitting IGE. Estimations were done following Bayesian procedures. Heritability estimates obtained with classic animal model for all studied traits were medium-high. The additional heritable variation captured by IGE supposed that the ratios of total genetic variance to phenotypic variance (T2) were higher than the heritability estimates obtained with the classic model, except for occupation time trait, when a lower value (0.20 ± 0.19) was estimated. This is due to a high and negative correlation between IGE and direct genetic effects (DGEs) of this particular trait (−0.78 ± 0.27). Results from classic animal model do not evidence a clear role of FBT to improve the accuracy of breeding value predictions for PT; only average daily feeding rate seems to show a positive correlation (around 0.50 to 0.60) with average daily gain, average daily feed consumption and backfat thickness. However, when IGE model was fitted, the number of estimates of genetic correlations between FBT and PT showing a relevant magnitude increased, generally for the correlations between IGE of FBT and DGE of PT; or particularly for the correlations between IGE of average daily feeding frequency, and the IGE of all the PT, except average daily gain. Thus, in evaluations using the animal model with IGE fitted, the inclusion of FBT could aid the improvement of the accuracy of breeding value predictions for PT. This is a consequence of the improved genetic relationships between traits that can be fitted when considering such models.info:eu-repo/semantics/publishedVersio

Ankle-brachial index: more than a diagnostic test?

The ankle-brachial index (ABI) is the relationship between the systolic blood pressure taken at the ankle level and the brachial artery. A pathological ABI (<0.90 or >1.40) indicates the presence of peripheral artery disease (PAD). Many studies indicate the great utility of this test in the diagnosis of PAD due to its ease of use, reproducibility, low cost, and high cost-effectiveness. This evaluation can be directly correlated with cardiovascular morbidity and mortality; however, it has recently been confirmed that a low ABI can be a predictor of major cardiovascular events, as it is related to diabetes mellitus, chronic coronary disease, stroke, and more. The objective of this work was to review the current evidence on the importance of ABI in the diagnosis of PAD and its main role as a predictor of cardiovascular morbidity and mortality.El índice tobillo-brazo (ITB) es la relación entre la presión arterial sistólica tomada entre el tobillo y la arteria braquial. Un ITB patológico (<0,90 o >1,40) indica la presencia de enfermedad arterial periférica (EAP). Muchos estudios muestran la gran utilidad de esta prueba en el diagnóstico de la EAP debido a su facilidad de uso, reproducibilidad, bajo coste y alta rentabilidad. Esta evaluación puede correlacionarse directamente con la morbilidad y mortalidad cardiovascular; sin embargo, recientemente se ha confirmado que un ITB bajo puede ser un predictor de eventos cardiovasculares mayores, ya que está relacionado con la diabetes mellitus, la enfermedad coronaria crónica y el ictus, entre otros. El objetivo de este trabajo fue revisar la evidencia actual sobre la importancia del ITB en el diagnóstico de la EAP y su papel principal como predictor de morbilidad y mortalidad cardiovascular

Diferencias fisiológicas y segregación de microhábitat en dos especies de crustáceos porcelánidos intermareales (Género Petrolisthes) en la costa sur de Chile

Intertidal crustaceans have a high degree of physiological plasticity, which allows them to withstand periods of water emersion. In this study we examine the physiological constraints that determine the distribution and abundance of the intertidal porcellanid crabs Petrolisthes laevigatus and Petrolisthes violaceus. This study evaluates the distribution and abundance of the two species at different tidal heights, in relation to haemocyanin concentration and LDH activity, resistance to air desiccation, thermal tolerance, and resistance to hypoxic water. The results showed that Petrolisthes laevigatus was more abundant at the high tide level than Petrolisthes violaceus, which was more abundant at the low tide level. Petrolisthes laevigatus showed greater tolerance to high temperatures and lower tolerance to desiccation when exposed to air than P. violaceus, which was also more tolerant to hypoxia during prolonged exposure. No differences were found in haemocyanin concentration and LDH activity. These findings support the idea of an evolutionary gradient towards terrestrial adaptations. Of the two species, Petrolisthes laevigatus showed the most advanced physiological features for semi-terrestrial specialization.Los crustáceos intermareales poseen un alto grado de plasticidad fisiológica, lo que les permite soportar periodos prolongados de emersión. En este estudio se examinaron algunas restricciones fisiológicas que determinan la distribución y abundancia de los porcelánidos intermareales Petrolisthes laevigatus y Petrolisthes violaceus. En este estudio se evaluó la distribución de estas dos especies a diferentes niveles del intermareal, relacionándolos con la concentración de hemocianina y actividad de la enzima LDH, resistencia a la desecación, tolerancia termal y la resistencia a agua hipóxica. Los resultados mostraron una mayor abundancia de P. laevigatus en la zona alta del intermareal y de P. violaceus en la zona baja. P. laevigatus mostró una mayor tolerancia a altas temperaturas y una menor tolerancia a la desecación durante la exposición aérea que P. violaceus, que además fue mas tolerante a prolongadas exposiciones a la de hipoxia. No se encontraron diferencias en la concentración de hemocianina y actividad de LDH entre las especies. Estos resultados apoyan la idea de un gradiente evolutivo hacia la los sistemas terrestres. P. laevigatus mostró más adecuaciones fisiológicas para la especialización semi-terrestre

Procedimientos de analgesia regional en el manejo del dolor crónico

ResumenLos bloqueos nerviosos con anestésicos locales o agentes neurolíticos se han empleado desde 1881. En la actualidad se utilizan con fines de diagnódtico, tratamiento y profilaxis. Las bases científicas de bloqueos nerviosos todavía no son muy claras; sin embargo, hay muchas publicaciones en la literatura médica que nos pueden aclarar cuál es el impacto de estos procedimientos en el manejo del dolor crónico. En este artículo se discuten algunos de los bloqueos que se utilizan con más frecuencia en clínica del dolor.Palabras clave: Bloqueos nerviosos, dolor crónico, enestesia regional

On the Metric Dimension of Cartesian Products of Graphs

A set S of vertices in a graph G resolves G if every vertex is uniquely determined by its vector of distances to the vertices in S. The metric dimension of G is the minimum cardinality of a resolving set of G. This paper studies the metric dimension of cartesian products G*H. We prove that the metric dimension of G*G is tied in a strong sense to the minimum order of a so-called doubly resolving set in G. Using bounds on the order of doubly resolving sets, we establish bounds on G*H for many examples of G and H. One of our main results is a family of graphs G with bounded metric dimension for which the metric dimension of G*G is unbounded