9,237 research outputs found
COPYRIGHTS, COMPETITION AND DEVELOPMENT: THE CASE OF THE MUSIC INDUSTRY
The economic importance of copyright industries in developed market economies has been well documented. Although less important in developing countries, this is likely to change with the growing weight of the service sector in these economies and its importance for their closer integration into the global market economy. This paper analyses the relationship between the copyright and income generation in the audio-visual sector, in particular music, and argues that the appropriate copyright administration is essential in creating the conditions for a viable music industry in developing countries. However, an effective copyright regime is not, by itself, sufficient to guarantee a flourishing music industry, and other institutional arrangements will be needed in countries looking to better exploit their musical resources.
Insights from ARPES for an undoped, four-layered, two-gap high-T_c superconductor
An undoped cuprate with apical fluorine and inner (i) and outer (o)
CuO2-layers is a 60 K superconductor whose Fermi surface (FS) has large n- and
p-doped sheets with the SC gap on the n-sheet twice that on the p -sheet (Y.
Chen et al.). The Fermi surface is not reproduced by the LDA, but the screening
must be substantially reduced due to electronic correlations, and oxygen in the
o-layers must be allowed to dimple outwards. This charges the i-layers by
0.01|e|, causes an 0.4 eV Madelung-potential difference between the i and o
-layers, quenches the i-o hopping, and localizes the n-sheets onto the
i-layers, thus protecting their d-wave pairs from being broken by scattering on
impurities in the BaF layers. The correlation-reduced screening strengthens the
coupling to z-axis phonons.Comment: 4 pages, 3 figure
Constraining and Dark Energy with Gamma-Ray Bursts
An relationship with a small
scatter for current -ray burst (GRB) data was recently reported, where
is the beaming-corrected -ray energy and
is the peak energy in the local observer frame. By considering this
relationship for a sample of 12 GRBs with known redshift, peak energy, and
break time of afterglow light curves, we constrain the mass density of the
universe and the nature of dark energy. We find that the mass density
(at the confident level) for a flat
universe with a cosmological constant, and the parameter of an assumed
static dark-energy equation of state ().
Our results are consistent with those from type Ia supernovae. A larger sample
established by the upcoming {\em Swift} satellite is expected to provide
further constraints.Comment: 8 pages including 4 figures, to appear in ApJ Letters, typos
correcte
Theory of the magnetoeletric effect in a lightly doped high-Tc cuprate
In a recent study Viskadourakis et al. discovered that extremely underdoped
La_2CuO_(4+x) is a relaxor ferroelectric and a magnetoelectric material at low
temperatures. It is further observed that the magnetoelectric response is
anisotropic for different directions of electric polarization and applied
magnetic field. By constructing an appropriate Landau theory, we show that a
bi-quadratic magnetoelectric coupling can explain the experimentally observed
polarization dependence on magnetic field. This coupling leads to several novel
low-temperature effects including a feedback enhancement of the magnetization
below the ferroelectric transition, and a predicted magnetocapacitive effect.Comment: 5 pages, 4 figure
Techniques for Observing Binaries in Other Galaxies
I present an overview of the techniques used for detecting and following up
binaries in nearby galaxies and present the current census of extragalactic
binaries, with a focus on eclipsing systems. The motivation for looking in
other galaxies is the use of eclipsing binaries as distance indicators and as
probes of the most massive stars.Comment: 5 pages, 1 table, to appear in the proceedings of the IAUS 282 on
"From Interacting Binaries to Exoplanets: Essential Modelling Tools"
(Tatranska Lomnica, Slovakia, July 2011), Cambridge University Pres
New model for surface fracture induced by dynamical stress
We introduce a model where an isotropic, dynamically-imposed stress induces
fracture in a thin film. Using molecular dynamics simulations, we study how the
integrated fragment distribution function depends on the rate of change and
magnitude of the imposed stress, as well as on temperature. A mean-field
argument shows that the system becomes unstable for a critical value of the
stress. We find a striking invariance of the distribution of fragments for
fixed ratio of temperature and rate of change of the stress; the interval over
which this invariance holds is determined by the force fluctuations at the
critical value of the stress.Comment: Revtex, 4 pages, 4 figures available upon reques
Current-induced membrane discharge
Possible mechanisms for over-limiting current (OLC) through aqueous
ion-exchange membranes (exceeding diffusion limitation) have been debated for
half a century. Flows consistent with electro-osmotic instability (EOI) have
recently been observed in microfluidic experiments, but the existing theory
neglects chemical effects and remains to be quantitatively tested. Here, we
show that charge regulation and water self-ionization can lead to OLC by
"current-induced membrane discharge" (CIMD), even in the absence of fluid flow.
Salt depletion leads to a large electric field which expels water co-ions,
causing the membrane to discharge and lose its selectivity. Since salt co-ions
and water ions contribute to OLC, CIMD interferes with electrodialysis (salt
counter-ion removal) but could be exploited for current-assisted ion exchange
and pH control. CIMD also suppresses the extended space charge that leads to
EOI, so it should be reconsidered in both models and experiments on OLC.Comment: 4.5 page
Electronic Structure of New LiFeAs High-Tc Superconductor
We present results of it ab initio LDA calculations of electronic structure
of "next generation" layered ironpnictide High-Tc superconductor LiFeAs
(Tc=18K). Obtained electronic structure of LiFeAs is very similar to recently
studied ReOFeAs (Re=La,Ce,Pr,Nd,Sm) and AFe2As2 (A=Ba,Sr) compounds. Namely
close to the Fermi level its electronic properties are also determined ma inly
by Fe 3d-orbitals of FeAs4 two-dimensional layers. Band dispersions of LiFeAs
are very similar to the LaOFeAs and BaFe2As2 systems as well as the shape of
the Fe-3d density o f states and Fermi surface.Comment: 4 pages, 5 figures; Electronic structure improved with respect to new
experimental crystal structure dat
Scaling behavior in the dynamics of a supercooled Lennard-Jones mixture
We present the results of a large scale molecular dynamics computer
simulation of a binary, supercooled Lennard-Jones fluid. At low temperatures
and intermediate times the time dependence of the intermediate scattering
function is well described by a von Schweidler law. The von Schweidler exponent
is independent of temperature and depends only weakly on the type of
correlator. For long times the correlation functions show a Kohlrausch behavior
with an exponent that is independent of temperature. This dynamical
behavior is in accordance with the mode-coupling theory of supercooled liquids.Comment: 6 pages, RevTex, three postscript figures available on request,
MZ-Physics-10
Collective Modes of Massive Dirac Fermions in Armchair Graphene Nanoribbons
We report the plasmon dispersion characteristics of intrinsic and extrinsic
armchair graphene nanoribbons of atomic width N = 5 using a p_z-orbital tight
binding model with third-nearest-neighbor (3nn) coupling. The coupling
parameters are obtained by fitting the 3nn dispersions to that of an extended
Huckel theory. The resultant massive Dirac Fermion system has a band gap E_g
\approx 64 meV. The extrinsic plasmon dispersion relation is found to approach
a common dispersion curve as the chemical potential increases, whereas
the intrinsic plasmon dispersion relation is found to have both energy and
momentum thresholds. We also report an analytical model for the extrinsic
plasmon group velocity in the q \rightarrow 0 limit
- …