1,007 research outputs found
Four-dimensional polymer collapse II: Interacting self-avoiding trails
We have simulated four-dimensional interacting self-avoiding trails (ISAT) on
the hyper-cubic lattice with standard interactions at a wide range of
temperatures up to length 4096 and at some temperatures up to length 16384. The
results confirm the earlier prediction (using data from a non-standard model at
a single temperature) of a collapse phase transition occurring at finite
temperature. Moreover they are in accord with the phenomenological theory
originally proposed by Lifshitz, Grosberg and Khokhlov in three dimensions and
recently given new impetus by its use in the description of simulational
results for four-dimensional interacting self-avoiding walks (ISAW). In fact,
we argue that the available data is consistent with the conclusion that the
collapse transitions of ISAT and ISAW lie in the same universality class, in
contradiction with long-standing predictions. We deduce that there exists a
pseudo-first order transition for ISAT in four dimensions at finite lengths
while the thermodynamic limit is described by the standard polymer mean-field
theory (giving a second-order transition), in contradiction to the prediction
that the upper critical dimension for ISAT is .Comment: 23 pages, 8 figure
Notes on some plant collections from Bachok and several forest reserves in Kelantan
A botanical survey of Bachok and various forest reserves at Jeram Linang, Jeram Pasu and Bukit Bakar was part of an expedition from 14–20 June 2008 carried out by the IOES (Institute of Ocean and Earth Sciences) University of Malaya to survey and prepare an inventory of the biodiversity of the coastal region around Bachok, Kelantan. A total of 54 species from 30 families, consisting of seashore and mangrove plants were identified from the coastal area of Bachok and Semerak; while 89 species of flowering plants representing 44 families, a single gymnosperm, Agathis borneensis (Araucariaceae); and 15 genera and 23 species of mosses (from 10 families) were recorded in the three forest reserves. Several of the species collected were rarely found outside Kelantan.
Satu survei tumbuhan di Bachok dan beberapa hutan simpanan termasuk Jeram Linang, Jeram Pasu dan Bukit Bakar, Kelantan adalah sebahagian ekspedisi survei biodiversiti kawasan pantai di sekitar Bachok Kelantan oleh IOES (Institute of Ocean and Earth Sciences) Universiti Malaya pada 14–20 Jun 2008. Sejumlah 54 spesies daripada 30 famili tumbuhan pantai dan bakau dikenalpasti dari kawasan pantai Bachok dan Semerak; sedangkan 89 spesies tumbuhan berbunga (mewakili 44 famili), satu gimnosperma, Agathis borneensis (Araucariaceae); serta 15 genera dan 23 spesies daripada 10 famili lumut sejati telah direkodkan di kawasan sekitar Jeram Linang, Jeram Pasu dan Hutan Lipur Bukit Bakar. Beberapa spesies yang dikutip adalah jarang ditemui di luar Kelantan
Superconductivity in graphene stacks: from the bilayer to graphite
We study the superconducting phase transition, both in a graphene bilayer and
in graphite. For that purpose we derive the mean-field effective potential for
a stack of graphene layers presenting hopping between adjacent sheets. For
describing superconductivity, we assume there is an on-site attractive
interaction between electrons and determine the superconducting critical
temperature as a function of the chemical potential. This displays a
dome-shaped curve, in agreement with previous results for two-dimensional Dirac
fermions. We show that the hopping between adjacent layers increases the
critical temperature for small values of the chemical potential. Finally, we
consider a minimal model for graphite and show that the transition temperature
is higher than that for the graphene bilayer for small values of chemical
potential. This might explain why intrinsic superconductivity is observed in
graphite
Parametrization and Classification of 20 Billion LSST Objects: Lessons from SDSS
The Large Synoptic Survey Telescope (LSST) will be a large, wide-field
ground-based system designed to obtain, starting in 2015, multiple images of
the sky that is visible from Cerro Pachon in Northern Chile. About 90% of the
observing time will be devoted to a deep-wide-fast survey mode which will
observe a 20,000 deg region about 1000 times during the anticipated 10
years of operations (distributed over six bands, ). Each 30-second long
visit will deliver 5 depth for point sources of on average.
The co-added map will be about 3 magnitudes deeper, and will include 10 billion
galaxies and a similar number of stars. We discuss various measurements that
will be automatically performed for these 20 billion sources, and how they can
be used for classification and determination of source physical and other
properties. We provide a few classification examples based on SDSS data, such
as color classification of stars, color-spatial proximity search for wide-angle
binary stars, orbital-color classification of asteroid families, and the
recognition of main Galaxy components based on the distribution of stars in the
position-metallicity-kinematics space. Guided by these examples, we anticipate
that two grand classification challenges for LSST will be 1) rapid and robust
classification of sources detected in difference images, and 2) {\it
simultaneous} treatment of diverse astrometric and photometric time series
measurements for an unprecedentedly large number of objects.Comment: Presented at the "Classification and Discovery in Large Astronomical
Surveys" meeting, Ringberg Castle, 14-17 October, 200
E.U. paediatric MOG consortium consensus: Part 4 – Outcome of paediatric myelin oligodendrocyte glycoprotein antibody-associated disorders
There is increasing knowledge on the role of antibodies against myelin oligodendrocyte glycoprotein
(MOG-abs) in acquired demyelinating syndromes and autoimmune encephalitis in children. Better understanding and prediction of outcome is essential to guide treatment protocol decisions. Therefore, this
part of the Paediatric European Collaborative Consensus provides an oversight of existing knowledge of
clinical outcome assessment in paediatric MOG-ab-associated disorders (MOGAD). The large heterogeneity in disease phenotype, disease course, treatment and follow-up protocols is a major obstacle for
reliable prediction of outcome. However, the clinical phenotype of MOGAD appears to be the main
determinant of outcome. Patients with a transverse myelitis phenotype in particular are at high r
B_s --> mu+ mu- decay in the R-parity violating minimal supergravity
We study B_s --> mu+ mu- in the context of the R-parity violating minimal
supergravity in the high tan beta regime. We find that the lowest value of the
branching ratio can go well below the present LHCb sensitivity and hence B_s
--> mu+ mu- can even be invisible to the LHC. We also find that the present
upper bound on Br(B_s --> mu+ mu-) puts strong constraint on the minimal
supergravity parameter space. The constraints become more severe if the upper
bound is close to its standard model prediction.Comment: 18 pages, 10 figures; version to be published in European Physical
Journal
Calculation of two-loop virtual corrections to b --> s l+ l- in the standard model
We present in detail the calculation of the virtual O(alpha_s) corrections to
the inclusive semi-leptonic rare decay b --> s l+ l-. We also include those
O(alpha_s) bremsstrahlung contributions which cancel the infrared and mass
singularities showing up in the virtual corrections. In order to avoid large
resonant contributions, we restrict the invariant mass squared s of the lepton
pair to the range 0.05 < s/mb^2 < 0.25. The analytic results are represented as
expansions in the small parameters s/mb^2, z = mc^2/mb^2 and s/(4 mc^2). The
new contributions drastically reduce the renormalization scale dependence of
the decay spectrum. For the corresponding branching ratio (restricted to the
above s-range) the renormalization scale uncertainty gets reduced from +/-13%
to +/-6.5%.Comment: 41 pages including 9 postscript figures; in version 2 some typos and
inconsistent notation correcte
Protective Effects of Platycodon grandiflorum Aqueous Extract on Thioacetamide-induced Fulminant Hepatic Failure in Mice
The aim of the present study was to evaluate the protective activity of aqueous extract
from Platycodon grandiflorum (BC703) on thioacetamide (TA)-induced
hepatotoxicity in mice. We found that BC703 significantly decreased mortality and the
change in serum transaminase following TA administration. The group treated with BC703 at
doses of 1, 5, and 10 mg/kg produced significant hepatoprotective effects against
TA-induced liver damage by decreasing the activities of serum enzymes, nitric oxide and
lipid peroxidation in dose-dependent manners. Histopathological studies further
substantiated the protective effect of BC703. These results show the hepatoprotective
activity of aqueous extract from Platycodon grandiflorum on
thioacetamide-induced fulminant hepatic failure
Neutrino Interactions in Hot and Dense Matter
We study the charged and neutral current weak interaction rates relevant for
the determination of neutrino opacities in dense matter found in supernovae and
neutron stars. We establish an efficient formalism for calculating differential
cross sections and mean free paths for interacting, asymmetric nuclear matter
at arbitrary degeneracy. The formalism is valid for both charged and neutral
current reactions. Strong interaction corrections are incorporated through the
in-medium single particle energies at the relevant density and temperature. The
effects of strong interactions on the weak interaction rates are investigated
using both potential and effective field-theoretical models of matter. We
investigate the relative importance of charged and neutral currents for
different astrophysical situations, and also examine the influence of
strangeness-bearing hyperons. Our findings show that the mean free paths are
significantly altered by the effects of strong interactions and the
multi-component nature of dense matter. The opacities are then discussed in the
context of the evolution of the core of a protoneutron star.Comment: 41 pages, 25 figure
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