354 research outputs found
Neutron star structure from QCD
In this review article, we argue that our current understanding of the
thermodynamic properties of cold QCD matter, originating from first principles
calculations at high and low densities, can be used to efficiently constrain
the macroscopic properties of neutron stars. In particular, we demonstrate that
combining state-of-the-art results from Chiral Effective Theory and
perturbative QCD with the current bounds on neutron star masses, the Equation
of State of neutron star matter can be obtained to an accuracy better than 30%
at all densities.Comment: Invited contribution to the EPJA Topical Issue "Exotic Matter in
Neutron Stars"; 10 pages, 13 figure
EMMI Rapid Reaction Task Force on "Thermalization in Non-abelian Plasmas"
Recently, different proposals have been put forward on how thermalization
proceeds in heavy-ion collisions in the idealized limit of very large nuclei at
sufficiently high energy. Important aspects of the parametric estimates at weak
coupling may be tested using well-established classical-statistical lattice
simulations of the far-from-equilibrium gluon dynamics. This has to be
confronted with strong coupling scenarios in related theories based on
gauge-string dualities. Furthermore, closely related questions about
far-from-equilibrium dynamics arise in early-universe cosmology and in
non-relativistic systems of ultracold atoms. These were central topics of the
EMMI Rapid Reaction Task Force meeting held on December 12-14, 2011, at the
University of Heidelberg, which we report on.Comment: 13 pages, summary of the EMMI Rapid Reaction Task Force on
"Thermalization in Non-abelian Plasmas", December 12-14, 2011, University of
Heidelberg, German
Detection of SARS-CoV-2 nucleocapsid antigen from serum can aid in timing of COVID-19 infection
SARS-CoV-2 RNA can be detected in respiratory samples for weeks after onset of COVID-19 disease. Therefore, one of the diagnostic challenges of PCR positive cases is differentiating between acute COVID-19 disease and convalescent phase. The presence of SARS-CoV-2 nucleocapsid antigen in serum and plasma samples of COVID-19 patients has been demonstrated previously. Our study aimed to characterize the analytical specificity and sensitivity of an enzyme-linked immunosorbent assay (Salocor SARS-CoV-2 Antigen Quantitative Assay Kit (c) (Salofa Ltd, Salo, Finland)) for the detection of SARS-CoV-2 nucleocapsid antigen in serum, and to characterize the kinetics of antigenemia. The evaluation material included a negative serum panel of 155 samples, and 126 serum samples from patients with PCR-confirmed COVID-19. The specificity of the Salocor SARS-CoV-2 serum nucleocapsid antigen test was 98.0 %. In comparison with simultaneous positive PCR from upper respiratory tract (URT) specimens, the test sensitivity was 91.7 %. In a serum panel in which the earliest serum sample was collected two days before the collection of positive URT specimen, and the latest 48 days after (median 1 day post URT sample collection), the serum N antigen test sensitivity was 95.6 % within 14 days post onset of symptoms. The antigenemia resolved approximately two weeks after the onset of disease and diagnostic PCR. The combination of simultaneous SARS-CoV-2 antigen and antibody testing appeared to provide useful in-formation for timing of COVID-19. Our results suggest that SARS-CoV-2 N-antigenemia may be used as a diag-nostic marker in acute COVID-19.Peer reviewe
Time singularities of correlators from Dirichlet conditions in AdS/CFT
Within AdS/CFT, we establish a general procedure for obtaining the leading
singularity of two-point correlators involving operator insertions at different
times. The procedure obtained is applied to operators dual to a scalar field
which satisfies Dirichlet boundary conditions on an arbitrary time-like surface
in the bulk. We determine how the Dirichlet boundary conditions influence the
singularity structure of the field theory correlation functions. New
singularities appear at boundary points connected by null geodesics bouncing
between the Dirichlet surface and the boundary. We propose that their
appearance can be interpreted as due to a non-local double trace deformation of
the dual field theory, in which the two insertions of the operator are
separated in time. The procedure developed in this paper provides a technical
tool which may prove useful in view of describing holographic thermalization
using gravitational collapse in AdS space.Comment: 30 pages, 3 figures. Version as in JHE
Two-color QCD via dimensional reduction
We study the thermodynamics of two-color QCD at high temperature and/or
density using a dimensionally reduced superrenormalizable effective theory,
formulated in terms of a coarse grained Wilson line. In the absence of quarks,
the theory is required to respect the Z(2) center symmetry, while the effects
of quarks of arbitrary masses and chemical potentials are introduced via soft
Z(2) breaking operators. Perturbative matching of the effective theory
parameters to the full theory is carried out explicitly, and it is argued how
the new theory can be used to explore the phase diagram of two-color QCD.Comment: 17 pages, 1 eps figure, jheppub style; v2: minor update, references
added, published versio
Novel flaviviruses from mosquitoes: Mosquito-specific evolutionary lineages within the phylogenetic group of mosquito-borne flaviviruses
Copyright © 2014 The Authors. Published by Elsevier Inc. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
Exploration of the phase diagram of 5D anisotropic SU(2) gauge theory
In this paper we attempt a non-perturbative study of the five dimensional,
anisotropic SU(2) gauge theory on the lattice using Monte-Carlo techniques. Our
goal is the exploration of the phase diagram, define the various phases and the
critical boundary lines. Three phases appear, two of them are continuations of
the Strong and the Weak coupling phases of pure 4d SU(2) to non-zero coupling
in the fifth transverse direction and they are separated by a
crossover transition, while the third phase is a 5D Coulombic phase. We provide
evidence that the phase transition between the 5D Coulomb phase and the Weak
coupling phase is a second order phase transition. Assuming that this result is
not altered when increasing the lattice volume we give a first estimate of the
associated critical exponents. This opens the possibility for a continuum
effective five dimensional field theory.Comment: 16 pages, 10 figures, essential improvement in the study of the phase
diagra
Low incidence of severe bacterial infections in hospitalised patients with COVID-19 : A population-based registry study
Background Bacterial infections complicating COVID-19 are rare but present a challenging clinical entity. The aim of this study was to evaluate the incidence, aetiology and outcome of severe laboratory-verified bacterial infections in hospitalised patients with COVID-19. Methods All laboratory-confirmed patients with COVID-19 admitted to specialised healthcare hospitals in the Capital Province of Finland during the first wave of COVID-19 between 27 February and 21 June 2020 were retrospectively studied. We gathered the blood and respiratory tract culture reports of these patients and analysed their association with 90-day case-fatality using multivariable regression analysis. Results A severe bacterial infection was diagnosed in 40/585 (6.8%) patients with COVID-19. The range of bacteria was diverse, and the most common bacterial findings in respiratory samples were gram-negative, and in blood cultures gram-positive bacteria. Patients with severe bacterial infection had longer hospital stay (mean 31; SD 20 days) compared to patients without (mean 9; SD 9 days; p < 0.001). Case-fatality was higher with bacterial infection (15% vs 11%), but the difference was not statistically significant (OR 1.38 CI95% 0.56-3.41). Conclusions Severe bacterial infection complicating COVID-19 was a rare occurrence in our cohort. Our results are in line with the current understanding that antibiotic treatment for hospitalised COVID-19 patients should only be reserved for situations where a bacterial infection is strongly suspected. The ever-evolving landscape of the pandemic and recent advances in immunomodulatory treatment of COVID-19 patients underline the need for continuous vigilance concerning the possibility and frequency of nosocomial bacterial infections.Peer reviewe
Holographic dilepton production in a thermalizing plasma
We determine the out-of-equilibrium production rate of dileptons at rest in
strongly coupled N=4 Super Yang-Mills plasma using the AdS/CFT correspondence.
Thermalization is achieved via the gravitational collapse of a thin shell of
matter in AdS_5 space and the subsequent formation of a black hole, which we
describe in a quasistatic approximation. Prior to thermalization, the dilepton
spectral function is observed to oscillate as a function of frequency, but the
amplitude of the oscillations decreases when thermal equilibrium is approached.
At the same time, we follow the flow of the quasinormal spectrum of the
corresponding U(1) vector field towards its equilibrium limit.Comment: 21 pages, 7 figures. v2: Version accepted for publication in JHEP;
minor modifications, added reference
Surveillance of endemic foci of tick-borne encephalitis in Finland 1995-2013 : evidence of emergence of new foci
The geographical risk areas for tick-borne encephalitis (TBE) in Finland remained the same until the beginning of the 21st century, but a considerable geographical expansion has been observed in the past 10 years. In order to support public health measures, the present study describes the number of laboratory-confirmed TBE cases and laboratory tests conducted and the associated trends by hospital district, with a particular emphasis on the suspected geographical risk areas. An additional investigation was conducted on 1,957 clinical serum samples throughout the country taken from patients with neurological symptoms to screen for undiagnosed TBE cases. This study identified new TBE foci in Finland, reflecting the spread of the disease into new areas. Even in the most endemic municipalities, transmission of TBE to humans occurred in very specific and often small foci. The number of antibody tests for TBE virus more than doubled (an increase by 105%) between 2007 and 2013. Analysis of the number of tests also revealed areas in which the awareness of clinicians may be suboptimal at present. However, it appears that underdiagnosis of neuroinvasive TBE is not common.Peer reviewe
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