3,342 research outputs found
Non-Fermi liquid behavior of SrRuO_3 -- evidence from infrared conductivity
The reflectivity of the itinerant ferromagnet SrRuO_3 has been measured
between 50 and 25,000 cm-1 at temperatures ranging from 40 to 300 K, and used
to obtain conductivity, scattering rate, and effective mass as a function of
frequency and temperature. We find that at low temperatures the conductivity
falls unusually slowly as a function of frequency (proportional to
\omega^{-1/2}), and at high temperatures it even appears to increase as a
function of frequency in the far-infrared limit. The data suggest that the
charge dynamics of SrRuO_3 are substantially different from those of
Fermi-liquid metals.Comment: 4 pages, 3 postscript figure
Reduction-Based Creative Telescoping for Algebraic Functions
Continuing a series of articles in the past few years on creative telescoping
using reductions, we develop a new algorithm to construct minimal telescopers
for algebraic functions. This algorithm is based on Trager's Hermite reduction
and on polynomial reduction, which was originally designed for hyperexponential
functions and extended to the algebraic case in this paper
Shear coordinate description of the quantised versal unfolding of D_4 singularity
In this paper by using Teichmuller theory of a sphere with four
holes/orbifold points, we obtain a system of flat coordinates on the general
affine cubic surface having a D_4 singularity at the origin. We show that the
Goldman bracket on the geodesic functions on the four-holed/orbifold sphere
coincides with the Etingof-Ginzburg Poisson bracket on the affine D_4 cubic. We
prove that this bracket is the image under the Riemann-Hilbert map of the
Poisson Lie bracket on the direct sum of three copies of sl_2. We realise the
action of the mapping class group by the action of the braid group on the
geodesic functions . This action coincides with the procedure of analytic
continuation of solutions of the sixth Painlev\'e equation. Finally, we produce
the explicit quantisation of the Goldman bracket on the geodesic functions on
the four-holed/orbifold sphere and of the braid group action.Comment: 14 pages, 2 picture
Non-Schlesinger Deformations of Ordinary Differential Equations with Rational Coefficients
We consider deformations of and matrix linear ODEs with
rational coefficients with respect to singular points of Fuchsian type which
don't satisfy the well-known system of Schlesinger equations (or its natural
generalization). Some general statements concerning reducibility of such
deformations for ODEs are proved. An explicit example of the general
non-Schlesinger deformation of -matrix ODE of the Fuchsian type with
4 singular points is constructed and application of such deformations to the
construction of special solutions of the corresponding Schlesinger systems is
discussed. Some examples of isomonodromy and non-isomonodromy deformations of
matrix ODEs are considered. The latter arise as the compatibility
conditions with linear ODEs with non-singlevalued coefficients.Comment: 15 pages, to appear in J. Phys.
Substantiating a political public sphere in the Scottish press : a comparative analysis
This article uses content analysis to characterize the performance of the media in a national public sphere, by setting apart those qualities that typify internal press coverage of a political event. The article looks at the coverage of the 1999 devolved Scottish election from the day before the election until the day after. It uses a word count to measure the election material in Scottish newspapers the Herald, the Press and Journal and the Scotsman, and United Kingdom newspapers the Guardian, the Independent and The Times, and categorizes that material according to discourse type, day and page selection. The article finds a number of qualities that typify the Scottish sample in particular, and might be broadly indicative of a political public sphere in action. Firstly, and not unexpectedly, it finds that the Scottish newspapers carry significantly more election coverage. Just as tellingly, though, the article finds that the Scottish papers offer a greater proportion of advice and background information, in the form of opinion columns and feature articles. It also finds that the Scottish papers place a greater concentration of both informative and evaluative material in the period before the vote, consistent with their making a contribution to informed political action. Lastly, the article finds that the Scottish sample situates coverage nearer the front of the paper and places a greater proportion on recto pages. The article therefore argues that the Scottish papers display features that distinguish them from the UK papers, and are broadly consistent with their forming part of a deliberative public sphere, and suggests that these qualities might be explored as a means of judging future media performance
Gamma-ray bursts and terrestrial planetary atmospheres
We describe results of modeling the effects on Earth-like planets of
long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary
effect is generation of nitrogen oxide compounds which deplete ozone. Ozone
depletion leads to an increase in solar UVB radiation at the surface, enhancing
DNA damage, particularly in marine microorganisms such as phytoplankton. In
addition, we expect increased atmospheric opacity due to buildup of nitrogen
dioxide produced by the burst and enhanced precipitation of nitric acid. We
review here previous work on this subject and discuss recent developments,
including further discussion of our estimates of the rates of impacting GRBs
and the possible role of short-duration bursts.Comment: 12 pages including 5 figures (4 in color). Added discussion of GRB
rates and biological effects. Accepted for publication in New Journal of
Physics, for special issue "Focus on Gamma-Ray Bursts
Older adultsâ experiences of sexual difficulties: Qualitative findings from the English Longitudinal Study on Ageing (ELSA)
There is a growing body of evidence demonstrating that sexual activity is important to the quality of life of older adults, and that it can be influenced by physical, psychological, and social factors. However, older adultsâ experiences of sexual difficulties remain relatively unexplored. This article draws on qualitative data collected as part of the English Longitudinal Study of Ageing (ELSA). Participants answered a Sexual Relationships and Activities Questionnaire (SRA-Q), which included an open comment box for further details, 1,084 (1/7) of which were completed. These data were analyzed using Template Analysis, and findings on the experiences of sexual difficulties are presented in this article. Sexual difficulties were contextualized within the couple relationship and could be detrimental to the relationship, particularly if the partner would not seek professional help. Participants reported that sexual difficulties could also have a negative impact on psychological well-being, described mainly as frustration, depression, and sadness. For some participants the supportive nature of their relationship buffered these impacts. Few had sought professional help; those who had reported helpful and unhelpful experiences. These findings add to the limited evidence base and have implications for health care in the context of global aging and a growing recognition of older adultsâ sexual rights
Optical study of the electronic phase transition of strongly correlated YbInCu_4
Infrared, visible and near-UV reflectivity measurements are used to obtain
conductivity as a function of temperature and frequency in YbInCu_4, which
exhibits an isostructural phase-transition into a mixed-valent phase below
T_v=42 K. In addition to a gradual loss of spectral weight with decreasing
temperature extending up to 1.5 eV, a sharp resonance appears at 0.25 eV in the
mixed-valent phase. This feature can be described in terms of excitations into
the Kondo (Abrikosov-Suhl) resonance, and, like the sudden reduction of
resistivity, provides a direct reflection of the onset of coherence in this
strongly correlated electron system.Comment: 4 pages, 3 figures (to appear in Phys. Rev. B
Transport properties of heavy particles in high Reynolds number turbulence
The statistical properties of heavy particle trajectories in high Reynolds
numbers turbulent flows are analyzed. Dimensional analysis assuming Kolmogorov
scaling is compared with the result of numerical simulation using a synthetic
turbulence advecting field. The non-Markovian nature of the fluid velocity
statistics along the solid particle trajectories is put into evidence, and its
relevance in the derivation of Lagrangian transport models is discussed.Comment: 30 pages, 11 eps figures included. To appear in Physics of Fluid
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