5,520 research outputs found
The effect of the Polyakov loop on the chiral phase transition
The Polyakov loop is included in the SU(2)_L x SU(2)_R chiral quark-meson
model by considering the propagation of the constituent quarks, coupled to the
(sigma,pi) meson multiplet, on the homogeneous background of a temporal gauge
field, diagonal in color space. The model is solved at finite temperature and
quark baryon chemical potential both in the chiral limit and for the physical
value of the pion mass by using an expansion in the number of flavors N_f.
Keeping the fermion propagator at its tree-level, a resummation on the pion
propagator is constructed which resums infinitely many orders in 1/N_f, where
O(1/N_f) represents the order at which the fermions start to contribute in the
pion propagator. The influence of the Polyakov loop on the tricritical or the
critical point in the mu_q-T phase diagram is studied for various forms of the
Polyakov loop potential.Comment: 8 pages, 3 figures, uses svepjCONF.clo, contribution to the
International Workshop on Hot & Cold Baryonic Matter 2010, 15-20 August,
Budapest, Hungar
Influence of the Polyakov loop on the chiral phase transition in the two flavor chiral quark model
The SU(2)_L x SU(2)_R chiral quark model consisting of the (sigma,pi) meson
multiplet and the constituent quarks propagating on the homogeneous background
of a temporal gauge field is solved at finite temperature and quark baryon
chemical potential mu_q using an expansion in the number of flavors N_f, both
in the chiral limit and for the physical value of the pion mass. Keeping the
fermion propagator at its tree-level, several approximations to the pion
propagator are investigated. These approximations correspond to different
partial resummations of the perturbative series. Comparing their solution with
a diagrammatically formulated resummation relying on a strict large-N_f
expansion of the perturbative series one concludes that only when the local
part of the approximated pion propagator resums infinitely many orders in 1/N_f
of fermionic contributions a sufficiently rapid crossover transition at mu_q=0
is achieved allowing for the existence of a tricritical point or a critical end
point in the mu_q-T phase diagram. The renormalization and the possibility of
determining the counterterms in the resummation provided by a strict large-N_f
expansion are investigated.Comment: 20 pages, 7 figures, 5 graphs, and 3 tables; uses revtex4-1, minor
corrections and investigation of the influence of the pion-fermion
setting-sun integral on the field equations for the Polyakov loop and its
conjugate. Version published in the Phys. Rev. D journa
Predicting Blood Glucose with an LSTM and Bi-LSTM Based Deep Neural Network
A deep learning network was used to predict future blood glucose levels, as
this can permit diabetes patients to take action before imminent hyperglycaemia
and hypoglycaemia. A sequential model with one long-short-term memory (LSTM)
layer, one bidirectional LSTM layer and several fully connected layers was used
to predict blood glucose levels for different prediction horizons. The method
was trained and tested on 26 datasets from 20 real patients. The proposed
network outperforms the baseline methods in terms of all evaluation criteria.Comment: 5 pages, submitted to 2018 14th Symposium on Neural Networks and
Applications (NEUREL
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Condition number estimates for combined potential boundary integral operators in acoustic scattering
We study the classical combined field integral equation formulations for time-harmonic acoustic scattering by a sound soft bounded obstacle, namely the indirect formulation due to Brakhage-Werner/Leis/Panic, and the direct formulation associated with the names of Burton and Miller. We obtain lower and upper bounds on the condition numbers for these formulations, emphasising dependence on the frequency, the geometry of the scatterer, and the coupling parameter. Of independent interest we also obtain upper and lower bounds on the norms of two oscillatory integral operators, namely the classical acoustic single- and double-layer potential operators
Clinical proteomics experiences in Japan on lung cancer treatments with EGFR -TKI-IRESSA
Comunicaciones a congreso
High-efficiency degenerate four wave-mixing in triply resonant nanobeam cavities
We demonstrate high-efficiency, degenerate four-wave mixing in triply
resonant Kerr photonic crystal (PhC) nanobeam cavities. Using a
combination of temporal coupled mode theory and nonlinear finite-difference
time-domain (FDTD) simulations, we study the nonlinear dynamics of resonant
four-wave mixing processes and demonstrate the possibility of observing
high-efficiency limit cycles and steady-state conversion corresponding to
% depletion of the pump light at low powers, even including
effects due to losses, self- and cross-phase modulation, and imperfect
frequency matching. Assuming operation in the telecom range, we predict close
to perfect quantum efficiencies at reasonably low 50 mW input powers in
silicon micrometer-scale cavities
In-flight dissipation as a mechanism to suppress Fermi acceleration
Some dynamical properties of time-dependent driven elliptical-shaped billiard
are studied. It was shown that for the conservative time-dependent dynamics the
model exhibits the Fermi acceleration [Phys. Rev. Lett. 100, 014103 (2008)]. On
the other hand, it was observed that damping coefficients upon collisions
suppress such phenomenon [Phys. Rev. Lett. 104, 224101 (2010)]. Here, we
consider a dissipative model under the presence of in-flight dissipation due to
a drag force which is assumed to be proportional to the square of the
particle's velocity. Our results reinforce that dissipation leads to a phase
transition from unlimited to limited energy growth. The behaviour of the
average velocity is described using scaling arguments.Comment: 4 pages, 5 figure
Geometric origin of scaling in large traffic networks
Large scale traffic networks are an indispensable part of contemporary human
mobility and international trade. Networks of airport travel or cargo ships
movements are invaluable for the understanding of human mobility
patterns\cite{Guimera2005}, epidemic spreading\cite{Colizza2006}, global
trade\cite{Imo2006} and spread of invasive species\cite{Ruiz2000}. Universal
features of such networks are necessary ingredients of their description and
can point to important mechanisms of their formation. Different
studies\cite{Barthelemy2010} point to the universal character of some of the
exponents measured in such networks. Here we show that exponents which relate
i) the strength of nodes to their degree and ii) weights of links to degrees of
nodes that they connect have a geometric origin. We present a simple robust
model which exhibits the observed power laws and relates exponents to the
dimensionality of 2D space in which traffic networks are embedded. The model is
studied both analytically and in simulations and the conditions which result
with previously reported exponents are clearly explained. We show that the
relation between weight strength and degree is , the relation
between distance strength and degree is and the relation
between weight of link and degrees of linked nodes is
on the plane 2D surface. We further analyse the
influence of spherical geometry, relevant for the whole planet, on exact values
of these exponents. Our model predicts that these exponents should be found in
future studies of port networks and impose constraints on more refined models
of port networks.Comment: 17 pages, 5 figures, 1 tabl
Spinning branes in Riemann-Cartan spacetime
We use the conservation law of the stress-energy and spin tensors to study
the motion of massive brane-like objects in Riemann-Cartan geometry. The
world-sheet equations and boundary conditions are obtained in a manifestly
covariant form. In the particle case, the resultant world-line equations turn
out to exhibit a novel spin-curvature coupling. In particular, the spin of a
zero-size particle does not couple to the background curvature. In the string
case, the world-sheet dynamics is studied for some special choices of spin and
torsion. As a result, the known coupling to the Kalb-Ramond antisymmetric
external field is obtained. Geometrically, the Kalb-Ramond field has been
recognized as a part of the torsion itself, rather than the torsion potential
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