878 research outputs found
Size reconstructibility of graphs
The deck of a graph is given by the multiset of (unlabelled) subgraphs
. The subgraphs are referred to as the cards of .
Brown and Fenner recently showed that, for , the number of edges of a
graph can be computed from any deck missing 2 cards. We show that, for
sufficiently large , the number of edges can be computed from any deck
missing at most cards.Comment: 15 page
Theory of Dynamic Stripe Induced Superconductivity
Since the recently reported giant isotope effect on T* [1] could be
consistently explained within an anharmonic spin-charge-phonon interaction
model, we consider here the role played by stripe formation on the
superconducting properties within the same model. This is a two-component
scenario and we recast its basic elements into a BCS effective Hamiltonian. We
find that the stripe formation is vital to high-Tc superconductivity since it
provides the glue between the two components to enhance Tc to the unexpectedly
large values observed experimentally.Comment: 7 pages, 2 figure
Summaries of plenary, symposia, and oral sessions at the XXII World Congress of Psychiatric Genetics, Copenhagen, Denmark, 12-16 October 2014
The XXII World Congress of Psychiatric Genetics, sponsored by the International Society of Psychiatric Genetics, took place in Copenhagen, Denmark, on 12-16 October 2014. A total of 883 participants gathered to discuss the latest findings in the field. The following report was written by student and postdoctoral attendees. Each was assigned one or more sessions as a rapporteur. This manuscript represents topics covered in most, but not all of the oral presentations during the conference, and contains some of the major notable new findings reported
Stroke Factors Associated with Thrombolysis Use in Hospitals in Singapore and US: A Cross-Registry Comparative Study
Background and Objectives: This paper aims to describe and compare the characteristics of 2 stroke populations in Singapore and in St. Louis, USA, and to document thrombolysis rates and contrast factors associated with its uptake in both populations. Methods: The stroke populations described were from the Singapore Stroke Registry (SSR) in -Singapore and the Cognitive Rehabilitation Research Group Stroke Registry (CRRGSR) in St. Louis, MO, USA. The registries were compared in terms of demographics and stroke risk factor history. Logistic regression was used to determine factors associated with thrombolysis uptake. Results: A total of 39,323 and 8,106 episodes were recorded in SSR and CRRGSR, respectively, from 2005 to 2012. Compared to CRRGSR, patients in SSR were older, male, and from the ethnic majority. Thrombolysis rates in SSR and CRRGSR were 2.5 and 8.2%, respectively, for the study period. History of ischemic heart disease or atrial fibrillation was associated with increased uptake in both populations, while history of stroke was associated with lower uptake. For SSR, younger age and males were associated with increased uptake, while having a history of smoking or diabetes was associated with decreased uptake. For CRRGSR, ethnic minority status was associated with decreased uptake. Conclusions: The comparison of stroke populations in Singapore and St Louis revealed distinct differences in clinicodemographics of the 2 groups. Thrombolysis uptake was driven by nonethnicity demographics in Singapore. Ethnicity was the only demographic driver of uptake in the CRRGSR population, highlighting the need to target ethnic minorities in increasing access to thrombolysis
The long journey from the giant-monopole resonance to the nuclear-matter incompressibility
Differences in the density dependence of the symmetry energy predicted by
nonrelativistic and relativistic models are suggested, at least in part, as the
culprit for the discrepancy in the values of the compression modulus of
symmetric nuclear matter extracted from the energy of the giant monopole
resonance in 208Pb. ``Best-fit'' relativistic models, with stiffer symmetry
energies than Skyrme interactions, consistently predict higher compression
moduli than nonrelativistic approaches. Relativistic models with compression
moduli in the physically acceptable range of K=200-300 MeV are used to compute
the distribution of isoscalar monopole strength in 208Pb. When the symmetry
energy is artificially softened in one of these models, in an attempt to
simulate the symmetry energy of Skyrme interactions, a lower value for the
compression modulus is indeed obtained. It is concluded that the proposed
measurement of the neutron skin in 208Pb, aimed at constraining the density
dependence of the symmetry energy and recently correlated to the structure of
neutron stars, will also become instrumental in the determination of the
compression modulus of nuclear matter.Comment: 9 pages with 2 (eps) figure
Bayesian Methods for Exoplanet Science
Exoplanet research is carried out at the limits of the capabilities of
current telescopes and instruments. The studied signals are weak, and often
embedded in complex systematics from instrumental, telluric, and astrophysical
sources. Combining repeated observations of periodic events, simultaneous
observations with multiple telescopes, different observation techniques, and
existing information from theory and prior research can help to disentangle the
systematics from the planetary signals, and offers synergistic advantages over
analysing observations separately. Bayesian inference provides a
self-consistent statistical framework that addresses both the necessity for
complex systematics models, and the need to combine prior information and
heterogeneous observations. This chapter offers a brief introduction to
Bayesian inference in the context of exoplanet research, with focus on time
series analysis, and finishes with an overview of a set of freely available
programming libraries.Comment: Invited revie
Parallel Excluded Volume Tempering for Polymer Melts
We have developed a technique to accelerate the acquisition of effectively
uncorrelated configurations for off-lattice models of dense polymer melts which
makes use of both parallel tempering and large scale Monte Carlo moves. The
method is based upon simulating a set of systems in parallel, each of which has
a slightly different repulsive core potential, such that a thermodynamic path
from full excluded volume to an ideal gas of random walks is generated. While
each system is run with standard stochastic dynamics, resulting in an NVT
ensemble, we implement the parallel tempering through stochastic swaps between
the configurations of adjacent potentials, and the large scale Monte Carlo
moves through attempted pivot and translation moves which reach a realistic
acceptance probability as the limit of the ideal gas of random walks is
approached. Compared to pure stochastic dynamics, this results in an increased
efficiency even for a system of chains as short as monomers, however
at this chain length the large scale Monte Carlo moves were ineffective. For
even longer chains the speedup becomes substantial, as observed from
preliminary data for
Magnetic and Thermodynamic Stability of SU(2) Yang-Mills Theory
SU(2) Yang-Mills theory at finite extension or, equivalently, at finite
temperature is probed by a homogeneous chromomagnetic field. We use a recent
modified axial gauge formulation which has the novel feature of respecting the
center symmetry in perturbation theory. The characteristic properties of the
Z_2-symmetric phase, an extension-dependent mass term and antiperiodic boundary
conditions, provide stabilization against magnetic field formation for
sufficiently small extension or high temperature. In an extension of this
investigation to the deconfined phase with broken center symmetry, the combined
constraints of thermodynamic and magnetic stability are shown to yield many of
the high temperature properties of lattice SU(2) gauge theory.Comment: 27 pages, LATEX, 7 postscript figures, corrected typo
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