57,801 research outputs found
Turbulent boundary layer characteristics of pointed slender bodies of revolution at supersonic speeds
Turbulent boundary layer characteristics of pointed slender bodies of revolution at supersonic speed
Vision and Reading Difficulties Part 5: Clinical protocol and the role of the eye-care practitioner
This series of articles has described various aspects of visual characteristics of reading difficulties and the background behind techniques such as the use of coloured filters in helping to reduce the difficulties that are experienced. The present article, which is the last in series, aims to describe a clinical protocol that can be used by the busy eye care practitioner for the investigation and management of such patients. It also describes the testing techniques that can be used for the various assessments. Warning: DO NOT LOOK AT FIGURE 7 IF YOU HAVE MIGRAINE OR EPILEPSY
Vision and Reading Difficulties Part 4: Coloured filters - how do they work?
This article is the fourth in a series of five about vision and reading difficulties. The first article provided a general overview and the second covered conventional optometric correlates of reading difficulties (e.g. binocular vision problems). The present article continues on from the third article by describing the use of coloured filters in treating a condition now known as visual stress. Visual stress is often associated with reading difficulties, but also a variety of other neurological conditions. This article concentrates on the possible mechanisms for the benefit from coloured filters, beginning with obvious peripheral factors. The terminology for this condition has changed over the years (e.g. Scotopic Sensitivity Syndrome, and Meares-Irlen Syndrome) and the issue of terminology is discussed at the end of this article. Warning: DO NOT LOOK AT FIGURE 6 ON PAGE 33 IF YOU HAVE A MIGRAINE OR EPILEPSY
Origin of Superconductivity in Boron-doped Diamond
Superconductivity of boron-doped diamond, reported recently at T_c=4 K, is
investigated exploiting its electronic and vibrational analogies to MgB2. The
deformation potential of the hole states arising from the C-C bond stretch mode
is 60% larger than the corresponding quantity in MgB2 that drives its high Tc,
leading to very large electron-phonon matrix elements. The calculated coupling
strength \lambda ~ 0.5 leads to T_c in the 5-10 K range and makes phonon
coupling the likely mechanism. Higher doping should increase T_c somewhat, but
effects of three dimensionality primarily on the density of states keep doped
diamond from having a T_c closer to that of MgB2.Comment: Four pages with two embedded figures, corrected fig1. (To appear in
Physical Review Letters(2004)
Computing the local pressure in molecular dynamics simulations
Computer simulations of inhomogeneous soft matter systems often require
accurate methods for computing the local pressure. We present a simple
derivation, based on the virial relation, of two equivalent expressions for the
local (atomistic) pressure in a molecular dynamics simulation. One of these
expressions, previously derived by other authors via a different route,
involves summation over interactions between particles within the region of
interest; the other involves summation over interactions across the boundary of
the region of interest. We illustrate our derivation using simulations of a
simple osmotic system; both expressions produce accurate results even when the
region of interest over which the pressure is measured is very small.Comment: 11 pages, 4 figure
Model of hard spheroplatelets near a hard wall
A system of hard spheroplatelets near an impenetrable wall is studied in the
low-density Onsager approximation. Spheroplatelets have optimal shape between
rods and plates, and the direct transition from the isotropic to biaxial
nematic phase is present. A simple local approximation for the one-particle
distribution function is used. Analytical results for the surface tension and
the entropy contributions are derived. The density and the order-parameter
profiles near the wall are calculated. The preferred orientation of the short
molecule axes is perpendicular to the wall. Biaxiality close to the wall can
appear only if the phase is biaxial in the bulk.Comment: 11 pages, 9 figures, revised version published in PR
Vision and Reading Difficulties Part 1: Specific learning difficulties and vision
This article is the first in a series of five about vision and reading difficulties, and provides an introduction and an overview of learning disabilities and specific learning difficulties. It outlines the role of the optometrist in helping people with such problems; it describes the symptoms that optometrists should look for and it provides an introduction of the evidence-based approach. The second article in this series will cover the optometric and orthoptic correlates of reading difficulties. Articles three and four will describe the use of coloured filters, including background, techniques, evidence, and mechanism. The final article will draw together the themes in the series of articles and discuss the clinical protocol and the role of the eye care practitioner in managing visual factors associated with reading difficulties
Vision and Reading Difficulties Part 3: Coloured filters - do they work?
This is the third article in a series of five on Vision and Reading Difficulties. The first article provided a general overview of learning disabilities and specific learning difficulties (SpLD). It outlined the role of the optometrist in helping people with SpLD. The second article covered conventional optometric correlates of reading difficulties (e.g. binocular vision problems) This article and the next will describe the use of coloured filters to treat a condition now know as "visual stress", which is often associated with reading difficulties; the symptoms of visual stress were described in Part 1. The terminology for this condition has changed over the years (e.g. Scotopic Sensitivity syndrome, Meares-Irlen syndrome). Terminology is discussed more in Part 4
Dynamics of uniaxial hard ellipsoids
We study the dynamics of monodisperse hard ellipsoids via a new event-driven
molecular dynamics algorithm as a function of volume fraction and aspect
ratio . We evaluate the translational and the rotational
diffusion coefficient and the associated isodiffusivity lines in the
plane. We observe a decoupling of the translational and rotational
dynamics which generates an almost perpendicular crossing of the
and isodiffusivity lines. While the self intermediate scattering
function exhibits stretched relaxation, i.e. glassy dynamics, only for large
and , the second order orientational correlator
shows stretching only for large and small values. We discuss these
findings in the context of a possible pre-nematic order driven glass
transition.Comment: accepted by Phys. Rev. Let
Vision and Reading Difficulties Part 2: Optometric correlates of reading difficulties
In this second article of the series on vision and reading difficulties, the optometric factors (for example refractive error and orthoptic function) that may be associated with reading problems are discussed in detail. The first article of this series introduced the correlates of, and interventions for, reading difficulties that have been supported by evidence-based research. This present article describes the optometric correlates more specifically, providing details of the aspects of visual function that ought to be considered for further investigation
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