Probability densities of a forced probe particle in glass: results from mode coupling theory and simulations of active microrheology

We investigate the displacements of a probe particle inside a glass, when a strong external force is applied to the probe (active nonlinear microrheology). Calculations within mode coupling theory are presented for glasses of hard spheres and compared to Langevin and Brownian dynamics simulations. Under not too strong forces where the probe remains trapped, the probe density distribution becomes anisotropic. It is shifted towards the direction of the force, develops an enhanced tail in that direction (signalled by a positive skewness), and exhibits different variances along and perpendicular to the force direction. A simple model of an harmonically trapped probe rationalizes the low force limit, with strong strain softening setting in at forces of the order of a few thermal energies per particle radius

Bond formation and slow heterogeneous dynamics in adhesive spheres with long--ranged repulsion: Quantitative test of Mode Coupling Theory

A colloidal system of spheres interacting with both a deep and narrow attractive potential and a shallow long-ranged barrier exhibits a prepeak in the static structure factor. This peak can be related to an additional mesoscopic length scale of clusters and/or voids in the system. Simulation studies of this system have revealed that it vitrifies upon increasing the attraction into a gel-like solid at intermediate densities. The dynamics at the mesoscopic length scale corresponding to the prepeak represents the slowest mode in the system. Using mode coupling theory with all input directly taken from simulations, we reveal the mechanism for glassy arrest in the system at 40% packing fraction. The effects of the low-q peak and of polydispersity are considered in detail. We demonstrate that the local formation of physical bonds is the process whose slowing down causes arrest. It remains largely unaffected by the large-scale heterogeneities, and sets the clock for the slow cluster mode. Results from mode-coupling theory without adjustable parameters agree semi-quantitatively with the local density correlators but overestimate the lifetime of the mesoscopic structure (voids).Comment: 10 pages, 8 figure

New methodological contributions to late antique rhetoric and historiography

Este trabajo pretende analizar el panorama bibliográfico actual sobre los estudios de retórica e historiografía del mundo tardo-antiguo. Tras un breve esbozo de las metodologías empleadas hasta el momento, se prestará especial atención a las recientes publicaciones de S. Elm y de R. Cribiore, dos trabajos que ofrecen nuevas perspectivas metodológicas en el análisis de las obras de figuras clave (el emperador Juliano, Gregorio de Nacianzo y Libanio de Antioquía) en el contexto político, religioso y cultural del siglo IVThis paper aims to analyse current bibliographical trends on the study of late antique rhetoric and historiography. After a brief survey of the modern methodologies, special attention will be paid to two recent publications by S. Elm and R. Cribiore. These works offer new methodological perspectives in the analysis of the works of key figures (the emperor Julian, Gregory of Nazianzus, and Libanius of Antioch) in the political, religious and cultural landscape of the fourth century ADProyecto de Investigación FFI2012-32012peerReviewe

Elementos hagiográficos en las ‘Homilías de las estatuas’ de Juan Crisóstomo

After the Riot of Statues of A.D. 387 in Antioch, John Chrysostom wrote twenty-four homilies where we can locate some hagiographical elements that show the permeability of the literary genres in the Late Antiquity, and increase the position of bishop Flavian within the Meletian party during the schism that divided the Antiochean church.Tras la revuelta de las estatuas de Antioquía del año 387, Juan Crisóstomo compuso 24 homilías en las que es posible detectar algunos elementos propios de la literatura hagiográfica en el retrato del obispo Flaviano, demostrando de esta manera la permeabilidad de los géneros literarios en la antigüedad tardía. Tales elementos deben inscribirse en el marco del cisma meleciano que enemistaba a las distintas facciones de la iglesia antioquena