Resonant Response in Non-equilibrium Steady States

The time-dependent probability density function of a system evolving towards a stationary state exhibits an oscillatory behavior if the eigenvalues of the corresponding evolution operator are complex. The frequencies \omega_n, with which the system reaches its stationary state, correspond to the imaginary part of such eigenvalues. If the system is further driven by a small and oscillating perturbation with a given frequency \omega, we formally prove that the linear response to the probability density function is enhanced when \omega = \omega_n. We prove that the occurrence of this phenomenon is characteristic of systems that reach a non-equilibrium stationary state. In particular we obtain an explicit formula for the frequency-dependent mobility in terms of the of the relaxation to the stationary state of the (unperturbed) probability current. We test all these predictions by means of numerical simulations considering an ensemble of non-interacting overdamped particles on a tilted periodic potential.Comment: 9 pages, 10 figures, submitted to Physical Review

Normal and anomalous diffusion of Brownian particles on disordered potentials

In this work we study the transition from normal to anomalous diffusion of Brownian particles on disordered potentials. The potential model consists of a series of "potential hills" (defined on unit cell of constant length) whose heights are chosen randomly from a given distribution. We calculate the exact expression for the diffusion coefficient in the case of uncorrelated potentials for arbitrary distributions. We particularly show that when the potential heights have a Gaussian distribution (with zero mean and a finite variance) the diffusion of the particles is always normal. In contrast when the distribution of the potential heights are exponentially distributed we show that the diffusion coefficient vanishes when system is placed below a critical temperature. We calculate analytically the diffusion exponent for the anomalous (subdiffusive) phase by using the so-called "random trap model". We test our predictions by means of Langevin simulations obtaining good agreement within the accuracy of our numerical calculations.Comment: 15 pages, 4 figure

Influencia del compromiso organizacional en la relación entre conflictos interpersonales y el síndrome de quemarse por el trabajo (burnout) en profesionales de servicios (salud y educación)

El objetivo de esta investigación es analizar la influencia de los conflictos interpersonales en el trabajo y del compromiso organizacional sobre el síndrome de quemarse por el trabajo (burnout), una respuesta psicológica al estrés laboral crónico que aparece en los profesionales del sector servicio que trabajan hacia personas. La muestra del estudio estuvo compuesta por 389 mexicanos de los sectores salud y educación. Los resultados obtenidos indicaron que los conflictos interpersonales tienen un efecto directo positivo y significativo sobre el síndrome de quemarse por el trabajo (Hipótesis 1), mientras que el efecto del compromiso organizacional resultó negativo y significativo (Hipótesis 2). Los resultados alcanzados mediante el análisis de regresión múltiple jerárquica permiten afirmar que la interacción entre ambas variables (conflictos interpersonales y compromiso organizacional) establece diferencias significativas en los niveles del síndrome de quemarse por el trabajo (Hipótesis 3). Se concluye que al potenciar el compromiso organizacional se contribuye a disminuir el síndrome de quemarse por el trabajo, aunque ante la presencia de conflictos interpersonales el personal con alto compromiso organizacional (normativo y afectivo) es más sensible al desarrollo del síndrome. Por tanto, se debe intervenir conjuntamente sobre la organización y los empleados

Estudios de acoplamiento molecular de nuevos análogos de quinolonas a la ADN girasa de Escherichia coli

Indexación: Scopus.Chemicals and CAS Registry Numbers: amino acid, 65072-01-7; ciprofloxacin, 85721-33-1; DNA topoisomerase (ATP hydrolysing); gatifloxacin, 112811-59-3, 180200-66-2; levofloxacin, 100986-85-4, 138199-71-0; lomefloxacin, 98079-51-7; moxifloxacin, 151096-09-2; nalidixic acid, 389-08-2; oxolinic acid, 14698-29-4; pipemidic acid, 51940-44-4; rufloxacin, 101363-10-4; sitafloxacin, 127254-12-0, 163253-35-8Context: Bacterial resistance to antibiotics is the inevitable consequence of the use of antimicrobial agents. Thus, quinolones are an important class of antibacterials; these agents generally consist of a 1-subtituted-1,4-dihydro-4-oxopyridine-3-carboxylic acid moiety combined with an aromatic or heteroaromatic ring fused at the 5- and 6-position. Aims: To determine the binding of quinolones to DNA gyrase of Escherichia coli. Methods: An analysis was performed using an in silico approach to determine, by docking calculations and energy descriptors, the conformer of 4‐oxo‐1,4‐dihydroquinoline skeleton that forms the most stable complex with DNA gyrase of E. coli. Results: The complex shows that the pose of the quinolones coincides with the amino acid residues Asp87, Thr88, Arg91 and Met92, which is expected to be critical in the binding of quinolones to DNA gyrase of E. coli. A series of quinolones were computationally designed, and the interactions between the quinolones and the amino acid residues of the DNA gyrase were calculated. Conclusions: Among the designed compounds, compounds 105 and 115 exhibit higher binding energy values and interact with amino acids Asp87, Thr88, Arg91 and Met92. © 2018 Journal of Pharmacy & Pharmacognosy Research.http://jppres.com/jppres/pdf/vol6/jppres18.368_6.5.386.pd