8,663 research outputs found
X-ray scattering study of two length scales in the critical fluctuations of CuGeO3
The critical fluctuations of CuGeO have been measured by synchrotron
x-ray scattering, and two length scales are clearly observed. The ratio between
the two length scales is found to be significantly different along the
axis, with the axis along the surface normal direction. We believe that
such a directional preference is a clear sign that surface random strains,
especially those caused by dislocations, are the origin of the long length
scale fluctuations.Comment: 5 pages, 4 figures, submitted to PR
Inelastic diffraction and color-singlet gluon-clusters in high-energy hadron-hadron and lepton-hadron collisions
It is proposed, that ``the colorless objects'' which manifest themselves in
large-rapidity-gap events are color-singlet gluon-clusters due to
self-organized criticality (SOC), and that optical-geometrical concepts and
methods are useful in examing the space-time properties of such objects. A
simple analytical expression for the -dependence of the inelastic single
diffractive cross section ( is the four-momentum transfer
squared) is derived. Comparison with the existing data and predictions for
future experiments are presented. The main differences and similarities between
the SOC-approach and the ``Partons in the Pomeron (Pomeron and
Reggeon)''-approach are discussed.Comment: 12 pages, 2 figure
Implications of Charge Ordering for Single-Particle Properties of High-Tc Superconductors
The consequences of disordered charge stripes and antiphase spin domains for
the properties of the high-temperature superconductors are studied. We focus on
angle-resolved photoemission spectroscopy and optical conductivity, and show
that the many unusual features of the experimentally observed spectra can be
understood naturally in this way. This interpretation of the data, when
combined with evidence from neutron scattering and NMR, suggests that
disordered and fluctuating stripe phases are a common feature of
high-temperature superconductors.Comment: 4 pages, figures by fax or mai
Predicting Anatomical Therapeutic Chemical (ATC) Classification of Drugs by Integrating Chemical-Chemical Interactions and Similarities
The Anatomical Therapeutic Chemical (ATC) classification system, recommended by the World Health Organization, categories drugs into different classes according to their therapeutic and chemical characteristics. For a set of query compounds, how can we identify which ATC-class (or classes) they belong to? It is an important and challenging problem because the information thus obtained would be quite useful for drug development and utilization. By hybridizing the informations of chemical-chemical interactions and chemical-chemical similarities, a novel method was developed for such purpose. It was observed by the jackknife test on a benchmark dataset of 3,883 drug compounds that the overall success rate achieved by the prediction method was about 73% in identifying the drugs among the following 14 main ATC-classes: (1) alimentary tract and metabolism; (2) blood and blood forming organs; (3) cardiovascular system; (4) dermatologicals; (5) genitourinary system and sex hormones; (6) systemic hormonal preparations, excluding sex hormones and insulins; (7) anti-infectives for systemic use; (8) antineoplastic and immunomodulating agents; (9) musculoskeletal system; (10) nervous system; (11) antiparasitic products, insecticides and repellents; (12) respiratory system; (13) sensory organs; (14) various. Such a success rate is substantially higher than 7% by the random guess. It has not escaped our notice that the current method can be straightforwardly extended to identify the drugs for their 2nd-level, 3rd-level, 4th-level, and 5th-level ATC-classifications once the statistically significant benchmark data are available for these lower levels
Limits on Phase Separation for Two-Dimensional Strongly Correlated Electrons
From calculations of the high temperature series for the free energy of the
two-dimensional t-J model we construct series for ratios of the free energy per
hole. The ratios can be extrapolated very accurately to low temperatures and
used to investigate phase separation. Our results confirm that phase separation
occurs only for J/t greater than 1.2. Also, the phase transition into the phase
separated state has Tc of approximately 0.25J for large J/t.Comment: 4 pages, 6 figure
Simulations of beam-beam and beam-wire interactions in RHIC
The beam-beam interaction is one of the dominant sources of emittance growth
and luminosity lifetime deterioration. A current carrying wire has been
proposed to compensate long-range beam-beam effects in the LHC and strong
localized long-range beam-beam effects are experimentally investigated in the
RHIC collider. Tune shift, beam transfer function, and beam loss rate are
measured in dedicated experiments. In this paper, we report on simulations to
study the effect of beam-wire interactions based on diffusive apertures, beam
loss rates, and beam transfer function using a parallelized weak-strong beam
simulation code (bbsimc). The simulation results are compared with measurements
performed in RHIC during 2007 and 2008.Comment: 15 pages, 36 figures, submitted to HB2008 PRST-AB Special Editio
Multi-user video streaming using unequal error protection network coding in wireless networks
In this paper, we investigate a multi-user video streaming system applying unequal error protection (UEP) network coding (NC) for simultaneous real-time exchange of scalable video streams among multiple users. We focus on a simple wireless scenario where users exchange encoded data packets over a common central network node (e.g., a base station or an access point) that aims to capture the fundamental system behaviour. Our goal is to present analytical tools that provide both the decoding probability analysis and the expected delay guarantees for different importance layers of scalable video streams. Using the proposed tools, we offer a simple framework for design and analysis of UEP NC based multi-user video streaming systems and provide examples of system design for video conferencing scenario in broadband wireless cellular networks
Dipolar interaction between two-dimensional magnetic particles
We determine the effective dipolar interaction between single domain
two-dimensional ferromagnetic particles (islands or dots), taking into account
their finite size. The first correction term decays as 1/D^5, where D is the
distance between particles. If the particles are arranged in a regular
two-dimensional array and are magnetized in plane, we show that the correction
term reinforces the antiferromagnetic character of the ground state in a square
lattice, and the ferromagnetic one in a triangular lattice. We also determine
the dipolar spin-wave spectrum and evaluate how the Curie temperature of an
ensemble of magnetic particles scales with the parameters defining the particle
array: height and size of each particle, and interparticle distance. Our
results show that dipolar coupling between particles might induce ferromagnetic
long range order at experimentally relevant temperatures. However, depending on
the size of the particles, such a collective phenomenon may be disguised by
superparamagnetism.Comment: 11 pages, 5 figure
Scaling violations: Connections between elastic and inelastic hadron scattering in a geometrical approach
Starting from a short range expansion of the inelastic overlap function,
capable of describing quite well the elastic pp and scattering data,
we obtain extensions to the inelastic channel, through unitarity and an impact
parameter approach. Based on geometrical arguments we infer some
characteristics of the elementary hadronic process and this allows an excellent
description of the inclusive multiplicity distributions in and
collisions. With this approach we quantitatively correlate the violations of
both geometrical and KNO scaling in an analytical way. The physical picture
from both channels is that the geometrical evolution of the hadronic
constituents is principally reponsible for the energy dependence of the
physical quantities rather than the dynamical (elementary) interaction itself.Comment: 16 pages, aps-revtex, 11 figure
Similarity of slow stripe fluctations between Sr-doped cuprates and oxygen-doped nickelates
Stripe fluctuations in La2NiO4.17 have been studied by 139La NMR using the
field and temperature dependence of the linewidth and relaxation rates. In the
formation process of the stripes the NMR line intensity is maximal below 230K,
starts to diminish around 140K, disappears around 50K and recovers at 4K. These
results are shown to be consistent with, but completely complementary to
neutron measurements, and to be generic for oxygen doped nickelates and
underdoped cuprates.Comment: 4 pages including 4 figure
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