1,507 research outputs found
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
Hecuba revisited: Euripidean Echoes in Libanius Or. 22.22
In describing a woman’s supplication of a magister militum after the Antioch riots of 387, Libanius revised Chrysostom’s version so as to invoke Hecuba and show the humanity of the magister militum and the value of pagan paideia.Research for this paper received financial support from the Spanish Ministry of Economy and Competitiveness (Research Group FFI2012-
32012)
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