3,139 research outputs found
Character Formulae and Partition Functions in Higher Dimensional Conformal Field Theory
A discussion of character formulae for positive energy unitary irreducible
representations of the the conformal group is given, employing Verma modules
and Weyl group reflections. Product formulae for various conformal group
representations are found. These include generalisations of those found by
Flato and Fronsdal for SO(3,2). In even dimensions the products for free
representations split into two types depending on whether the dimension is
divisible by four or not.Comment: 43 pages, uses harvmac,version 2 2 references added, minor typos
correcte
The Information Geometry of the Ising Model on Planar Random Graphs
It has been suggested that an information geometric view of statistical
mechanics in which a metric is introduced onto the space of parameters provides
an interesting alternative characterisation of the phase structure,
particularly in the case where there are two such parameters -- such as the
Ising model with inverse temperature and external field .
In various two parameter calculable models the scalar curvature of
the information metric has been found to diverge at the phase transition point
and a plausible scaling relation postulated: . For spin models the necessity of calculating in
non-zero field has limited analytic consideration to 1D, mean-field and Bethe
lattice Ising models. In this letter we use the solution in field of the Ising
model on an ensemble of planar random graphs (where ) to evaluate the scaling behaviour of the scalar curvature, and find
. The apparent discrepancy is traced
back to the effect of a negative .Comment: Version accepted for publication in PRE, revtex
Implications of Improved Higgs Mass Calculations for Supersymmetric Models
We discuss the allowed parameter spaces of supersymmetric scenarios in light
of improved Higgs mass predictions provided by FeynHiggs 2.10.0. The Higgs mass
predictions combine Feynman-diagrammatic results with a resummation of leading
and subleading logarithmic corrections from the stop/top sector, which yield a
significant improvement in the region of large stop masses. Scans in the pMSSM
parameter space show that, for given values of the soft supersymmetry-breaking
parameters, the new logarithmic contributions beyond the two-loop order
implemented in FeynHiggs tend to give larger values of the light CP-even Higgs
mass, M_h, in the region of large stop masses than previous predictions that
were based on a fixed-order Feynman-diagrammatic result, though the differences
are generally consistent with the previous estimates of theoretical
uncertainties. We re-analyze the parameter spaces of the CMSSM, NUHM1 and
NUHM2, taking into account also the constraints from CMS and LHCb measurements
of B_s to \mu+\mu- and ATLAS searches for MET events using 20/fb of LHC data at
8 TeV. Within the CMSSM, the Higgs mass constraint disfavours tan beta lesssim
10, though not in the NUHM1 or NUHM2.Comment: 22 pages, 17 figure
The Quasinormal Mode Spectrum of a Kerr Black Hole in the Eikonal Limit
It is well established that the response of a black hole to a generic
perturbation is characterized by a spectrum of damped resonances, called
quasinormal modes; and that, in the limit of large angular momentum (), the quasinormal mode frequency spectrum is related to the properties of
unstable null orbits. In this paper we develop an expansion method to explore
the link. We obtain new closed-form approximations for the lightly-damped part
of the spectrum in the large- regime. We confirm that, at leading order in
, the resonance frequency is linked to the orbital frequency, and the
resonance damping to the Lyapunov exponent, of the relevant null orbit. We go
somewhat further than previous studies to establish (i) a spin-dependent
correction to the frequency at order for equatorial ()
modes, and (ii) a new result for polar modes (). We validate the
approach by testing the closed-form approximations against frequencies obtained
numerically with Leaver's method.Comment: 18 pages, 3 tables, 3 figure
A Photometric Study of the Young Stellar Population Throughout the lambda Orionis Star-Forming Region
We present VRI photometry of 320,917 stars with 11 < R < 18 throughout the
lambda Orionis star-forming region. We statistically remove the field stars and
identify a representative PMS population throughout the interior of the
molecular ring. The spatial distribution of this population shows a
concentration of PMS stars around lambda Ori and in front of the B35 dark
cloud. Few PMS stars are found outside these pockets of high stellar density,
suggesting that star formation was concentrated in an elongated cloud extending
from B35 through lambda Ori to the B30 cloud. We find a lower limit for the
global stellar mass of about 500 Mo. We find that the global ratio of low- to
high-mass stars is similar to that predicted by the field initial mass
function, but this ratio varies strongly as a function of position in the
star-forming region. Locally, the star-formation process does not produce a
universal initial mass function. We construct a history of the star-forming
complex. This history incorporates a recent supernova to explain the
distribution of stars and gas today.Comment: 42 pages, 11 figures; to appear in the Astronomical Journa
Resistivity peak values at transition between fractional quantum Hall states
Experimental data available in the literature for peak values of the diagonal
resistivity in the transitions between fractional quantum Hall states are
compared with the theoretical predictions. It is found that the majority of the
peak values are close to the theoretical values for two-dimensional systems
with moderate mobilities.Comment: 3 pages, 1 figur
A pilot Internet "Value of Health" Panel: recruitment, participation and compliance
Objectives
To pilot using a panel of members of the public to provide preference data via the Internet
Methods
A stratified random sample of members of the general public was recruited and familiarised with the standard gamble procedure using an Internet based tool. Health states were perdiodically presented in "sets" corresponding to different conditions, during the study. The following were described: Recruitment (proportion of people approached who were trained); Participation (a) the proportion of people trained who provided any preferences and (b) the proportion of panel members who contributed to each "set" of values; and Compliance (the proportion, per participant, of preference tasks which were completed). The influence of covariates on these outcomes was investigated using univariate and multivariate analyses.
Results
A panel of 112 people was recruited. 23% of those approached (n = 5,320) responded to the invitation, and 24% of respondents (n = 1,215) were willing to participate (net = 5.5%). However, eventual recruitment rates, following training, were low (2.1% of those approached). Recruitment from areas of high socioeconomic deprivation and among ethnic minority communities was low. Eighteen sets of health state descriptions were considered over 14 months. 74% of panel members carried out at least one valuation task. People from areas of higher socioeconomic deprivation and unmarried people were less likely to participate. An average of 41% of panel members expressed preferences on each set of descriptions. Compliance ranged from 3% to 100%.
Conclusion
It is feasible to establish a panel of members of the general public to express preferences on a wide range of health state descriptions using the Internet, although differential recruitment and attrition are important challenges. Particular attention to recruitment and retention in areas of high socioeconomic deprivation and among ethnic minority communities is necessary. Nevertheless, the panel approach to preference measurement using the Internet offers the potential to provide specific utility data in a responsive manner for use in economic evaluations and to address some of the outstanding methodological uncertainties in this field
Limited access to HIV prevention in French prisons (ANRS PRI2DE): implications for public health and drug policy
International audienceABSTRACT: BACKGROUND: Overpopulation, poor hygiene and disease prevention conditions in prisons are major structural determinants of increased infectious risk within prison settings but evidence-based national and WHO guidelines provide clear indications on how to reduce this risk. We sought to estimate the level of infectious risk by measuring how French prisons adhere to national and WHO guidelines. METHODS: A nationwide survey targeting the heads of medical (all French prisons) and psychiatric (26 French prisons) units was conducted using a postal questionnaire and a phone interview mainly focusing on access to prevention interventions, i.e. bleach, opioid substitution treatment (OST), HBV vaccination and post-exposure prophylaxis (PEP) for French prisoners. Two scores were built reflecting adherence to national and WHO international guidelines, ranging from 0 (no adherence) to 10 (maximum adherence) and 0 to 9 respectively. RESULTS: A majority (N=113 (66%)) of the 171 prisons answered the questionnaires, representing 74% coverage (46,786 prisoners) of the French prison population: 108 were medical units and 12 were psychiatric units. Inmate access to prevention was poor. The median[IQR] score measuring adherence to national guidelines was quite low (4.5[2.5; 5.5]) but adherence to WHO guidelines was even lower 2.5[1.5; 3.5]; PEP was absent despite reported risky practices. Unsuitable OST delivery practices were frequently observed. CONCLUSIONS: A wide gap exists between HIV prevention policies and their application in prisons. Similar assessments in other countries may be needed to guide a global policy reform in prison settings. Adequate funding together with innovative interventions able to remove structural and ideological barriers to HIV prevention are now needed to motivate those in charge of prison health, to improve their working environment and to relieve French prisoners from their currently debilitating conditions
Characterization of a regulated form of phospholipase D in the yeast Saccharomyces cerevisiae
Regulation of Nonribosomal Peptide Synthesis: bis-Thiomethylation Attenuates Gliotoxin Biosynthesis in Aspergillus fumigatus
Gliotoxin is a redox-active nonribosomal peptide
produced by Aspergillus fumigatus. Like many other
disulfide-containing epipolythiodioxopiperazines, a
bis-thiomethylated form is also produced. In the
case of gliotoxin, bisdethiobis(methylthio)gliotoxin
(BmGT) is formed for unknown reasons by a cryptic
enzyme. Here, we identify the S-adenosylmethionine-
dependent gliotoxin bis-thiomethyltransferase
(GtmA), which converts dithiogliotoxin to BmGT.
This activity, which is induced by exogenous gliotoxin,
is only detectable in protein lysates of A. fumigatus
deficient in the gliotoxin oxidoreductase, gliT.
Thus, GtmA is capable of substrate bis-thiomethylation.
Deletion of gtmA completely abrogates BmGT
formation and we now propose that the purpose
of BmGT formation is primarily to attenuate gliotoxin
biosynthesis. Phylogenetic analysis reveals 124
GtmA homologs within the Ascomycota phylum.
GtmA is encoded outside the gliotoxin biosynthetic
cluster and primarily serves to negatively regulate
gliotoxin biosynthesis. This mechanism of postbiosynthetic
regulation of nonribosomal peptide synthesis
appears to be quite unusual
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