4,160 research outputs found
Isomonodromic deformatiion with an irregular singularity and hyperelliptic curve
In this paper, we extend the result of Kitaev and Korotkin to the case where
a monodromy-preserving deformation has an irregular singularity. For the
monodromy-preserving deformation, we obtain the -function whose
deformation parameters are the positions of regular singularities and the
parameter of an irregular singularity. Furthermore, the -function is
expressed by the hyperelliptic function moving the argument \z and
the period \B, where and the positions of regular singularities move
and \B, respectively.Comment: 23 pages, 2 figure
Copyright and cultural work: an exploration
This article first discusses the contemporary debate on cultural âcreativityâ and the economy. Second, it considers the current state of UK copyright law and how it relates to cultural work. Third, based on empirical research on British dancers and musicians, an analysis of precarious cultural work is presented. A major focus is how those who follow their art by way of âportfolioâ work handle their rights in ways that diverge significantly from the current simplistic assumptions of law and cultural policy. Our conclusions underline the distance between present top-down conceptions of what drives production in the cultural field and the actual practice of dancers and musicians
Signatures of electronic correlations in iron silicide
The intermetallic FeSi exhibits an unusual temperature dependence in its
electronic and magnetic degrees of freedom, epitomized by the crossover from a
low temperature non-magnetic semiconductor to a high temperature paramagnetic
metal with a Curie-Weiss like susceptibility. Many proposals for this
unconventional behavior have been advanced, yet a consensus remains elusive.
Using realistic many-body calculations, we here reproduce the signatures of the
metal-insulator crossover in various observables: the spectral function, the
optical conductivity, the spin susceptibility, and the Seebeck coefficient.
Validated by quantitative agreement with experiment, we then address the
underlying microscopic picture. We propose a new scenario in which FeSi is a
band-insulator at low temperatures and is metalized with increasing temperature
through correlation induced incoherence. We explain that the emergent
incoherence is linked to the unlocking of iron fluctuating moments which are
almost temperature independent at short time scales. Finally, we make explicit
suggestions for improving the thermoelectric performance of FeSi based systems.Comment: 4+ pages, and supplementary materia
Field Dependence of the Superconducting Basal Plane Anisotropy of TmNi2B2C
The superconductor TmNi2B2C possesses a significant four-fold basal plane
anisotropy, leading to a square Vortex Lattice (VL) at intermediate fields.
However, unlike other members of the borocarbide superconductors, the
anisotropy in TmNi2B2C appears to decrease with increasing field, evident by a
reentrance of the square VL phase. We have used Small Angle Neutron Scattering
measurements of the VL to study the field dependence of the anisotropy. Our
results provide a direct, quantitative measurement of the decreasing
anisotropy. We attribute this reduction of the basal plane anisotropy to the
strong Pauli paramagnetic effects observed in TmNi2B2C and the resulting
expansion of vortex cores near Hc2.Comment: 8 pages, 6 figures, 1 tabl
Nimbus 7 solar backscatter ultraviolet (SBUV) ozone products user's guide
Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as well as much detailed diagnostic information generated during the retrieval process. The Compressed Ozone (CPOZ) tape contains only that subset of HDSBUV information, including total ozone and ozone profiles, considered most useful for scientific studies. The Zonal Means Tape (ZMT) contains daily, weekly, monthly and quarterly averages of the derived quantities over 10 deg latitude zones
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
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
In-Situ Observation of Membrane Protein Folding during Cell-Free Expression.
Proper insertion, folding and assembly of functional proteins in biological membranes are key processes to warrant activity of a living cell. Here, we present a novel approach to trace folding and insertion of a nascent membrane protein leaving the ribosome and penetrating the bilayer. Surface Enhanced IR Absorption Spectroscopy selectively monitored insertion and folding of membrane proteins during cell-free expression in a label-free and non-invasive manner. Protein synthesis was performed in an optical cell containing a prism covered with a thin gold film with nanodiscs on top, providing an artificial lipid bilayer for folding. In a pilot experiment, the folding pathway of bacteriorhodopsin via various secondary and tertiary structures was visualized. Thus, a methodology is established with which the folding reaction of other more complex membrane proteins can be observed during protein biosynthesis (in situ and in operando) at molecular resolution
Deep SDSS optical spectroscopy of distant halo stars I. Atmospheric parameters and stellar metallicity distribution
We analyze a sample of tens of thousands of spectra of halo turnoff stars,
obtained with the optical spectrographs of the Sloan Digital Sky Survey (SDSS),
to characterize the stellar halo population "in situ" out to a distance of a
few tens of kpc from the Sun. In this paper we describe the derivation of
atmospheric parameters. We also derive the overall stellar metallicity
distribution based on F-type stars observed as flux calibrators for the
Baryonic Oscillations Spectroscopic Survey (BOSS). Our analysis is based on an
automated method that determines the set of parameters of a model atmosphere
that reproduces each observed spectrum best. We used an optimization algorithm
and evaluate model fluxes by means of interpolation in a precomputed grid. In
our analysis, we account for the spectrograph's varying resolution as a
function of fiber and wavelength. Our results for early SDSS (pre-BOSS upgrade)
data compare well with those from the SEGUE Stellar Parameter Pipeline (SSPP),
except for stars with logg (cgs units) lower than 2.5. An analysis of stars in
the globular cluster M13 reveals a dependence of the inferred metallicity on
surface gravity for stars with logg < 2.5, confirming the systematics
identified in the comparison with the SSPP. We find that our metallicity
estimates are significantly more precise than the SSPP results. We obtain a
halo metallicity distribution that is narrower and more asymmetric than in
previous studies. The lowest gravity stars in our sample, at tens of kpc from
the Sun, indicate a shift of the metallicity distribution to lower abundances,
consistent with what is expected from a dual halo system in the Milky Way.Comment: 10 pages, 5 figures, Table 1 includes model ugriz magnitudes for
stars with different atmospheric parameters in electronic forma
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