3,000 research outputs found
High-precision estimate of g4 in the 2D Ising model
We compute the renormalized four-point coupling in the 2d Ising model using
transfer-matrix techniques. We greatly reduce the systematic uncertainties
which usually affect this type of calculations by using the exact knowledge of
several terms in the scaling function of the free energy. Our final result is
g4=14.69735(3).Comment: 17 pages, revised version with minor changes, accepted for
publication in Journal of Physics
The uniformly frustrated two-dimensional XY model in the limit of weak frustration
We consider the two-dimensional uniformly frustrated XY model in the limit of
small frustration, which is equivalent to an XY system, for instance a
Josephson junction array, in a weak uniform magnetic field applied along a
direction orthogonal to the lattice. We show that the uniform frustration
(equivalently, the magnetic field) destabilizes the line of fixed points which
characterize the critical behaviour of the XY model for T <= T_{KT}, where
T_{KT} is the Kosterlitz-Thouless transition temperature: the system is
paramagnetic at any temperature for sufficiently small frustration. We predict
the critical behaviour of the correlation length and of gauge-invariant
magnetic susceptibilities as the frustration goes to zero. These predictions
are fully confirmed by the numerical simulations.Comment: 12 page
Renormalised four-point coupling constant in the three-dimensional O(N) model with N=0
We simulate self-avoiding walks on a cubic lattice and determine the second
virial coefficient for walks of different lengths. This allows us to determine
the critical value of the renormalized four-point coupling constant in the
three-dimensional N-vector universality class for N=0. We obtain g* =
1.4005(5), where g is normalized so that the three-dimensional
field-theoretical beta-function behaves as \beta(g) = - g + g^2 for small g. As
a byproduct, we also obtain precise estimates of the interpenetration ratio
Psi*, Psi* = 0.24685(11), and of the exponent \nu, \nu = 0.5876(2).Comment: 16 page
Ghost of a Shell: Magnetic Fields of Galactic Supershell GSH 006157
We identify a counterpart to a Galactic supershell in diffuse radio
polarisation, and use this to determine the magnetic fields associated with
this object. GSH 006157 has perturbed the polarised emission at
2.3GHz, as observed in the S-band Polarisation All Sky Survey (S-PASS),
acting as a Faraday screen. We model the Faraday rotation over the shell, and
produce a map of Faraday depth over the area across it. Such models require
information about the polarised emission behind the screen, which we obtain
from the Wilkinson Microwave Anisotropy Probe (WMAP), scaled from 23GHz to
2.3GHz, to estimate the synchrotron background behind GSH 006157.
Using the modelled Faraday thickness we determine the magnitude and the
plane-of-the-sky structure of the line-of-sight magnetic field in the shell. We
find a peak line-of-sight field strength of G. Our measurement probes weak magnetic fields
in a low-density regime (number densities of cm) of the ISM,
thus providing crucial information about the magnetic fields in the
partially-ionised phase.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Society. 19 pages, 19 figure
Topological susceptibility of SU(N) gauge theories at finite temperature
We investigate the large-N behavior of the topological susceptibility in
four-dimensional SU(N) gauge theories at finite temperature, and in particular
across the finite-temperature transition at Tc. For this purpose, we consider
the lattice formulation of the SU(N) gauge theories and perform Monte Carlo
simulations for N=4,6. The results indicate that the topological susceptibility
has a nonvanishing large-N limit for T<Tc, as at T=0, and that the topological
properties remain substantially unchanged in the low-temperature phase. On the
other hand, above the deconfinement phase transition, the topological
susceptibility shows a large suppression. The comparison between the data for
N=4 and N=6 hints at a vanishing large-N limit for T>Tc.Comment: 9 pages, 2 figs, a few discussions added, JHEP in pres
Multicritical Nishimori point in the phase diagram of the +- J Ising model on a square lattice
We investigate the critical behavior of the random-bond +- J Ising model on a
square lattice at the multicritical Nishimori point in the T-p phase diagram,
where T is the temperature and p is the disorder parameter (p=1 corresponds to
the pure Ising model). We perform a finite-size scaling analysis of
high-statistics Monte Carlo simulations along the Nishimori line defined by
, along which the multicritical point lies. The
multicritical Nishimori point is located at p^*=0.89081(7), T^*=0.9528(4), and
the renormalization-group dimensions of the operators that control the
multicritical behavior are y_1=0.655(15) and y_2 = 0.250(2); they correspond to
the thermal exponent \nu= 1/y_2=4.00(3) and to the crossover exponent \phi=
y_1/y_2=2.62(6).Comment: 23 page
Conversion of laparoscopic colorectal resection for cancer: What is the impact on short-term outcomes and survival?
Laparoscopic resection for colon and rectal cancer is associated with quicker return of bowel function, reduced postoperative morbidity rates and shorter length of hospital stay compared to open surgery, with no differences in long-term survival. Conversion to open surgery is reported in up to 30% of patients enrolled in randomized control trials comparing open and laparoscopic colorectal resection for cancer. In this review, reasons for conversion are anatomical-related factors, disease-related-factors and surgeon-related factors. Body mass index, local tumour extension and co-morbidities are independent predictors of conversion. The current evidence has shown that patients with converted resection for colon cancer have similar outcomes compared to patients undergoing a laparoscopic completed or open resection. The few studies that have assessed the outcomes after conversion of laparoscopic rectal resection reported significantly higher rates of complications and longer length of hospital stay in converted patients compared to laparoscopically treated patients. No definitive conclusions can be drawn when converted and open rectal resections are compared. Early and pre-emptive conversion appears to have more favourable outcomes than reactive conversion; however, further large studies are needed to better define the optimal timing of conversion. With regard to long-term oncologic outcome, overall and disease-free survival in the case of conversion in laparoscopic colorectal cancer surgery seems to be worse than those achieved in patients in whom resection was successfully completed by laparoscopy. Although a worse long-term oncologic outcome has been suggested, it remains difficult to draw a proper conclusion due to the heterogeneity of the long-term outcomes as well as the inclusion of both colon and rectal cancer patients in most of the studies. Therefore, we discuss the currently available evidence of the impact of conversion in laparoscopic resection for colon and rectal cancer on both short-term outcomes and long-term survival
Abelmoschus esculentus (L.): Bioactive Components Beneficial PropertiesFocused on Antidiabetic RoleFor Sustainable Health Applications
The main features of the okra, Abelmoschus esculentus (L.), are highlighted. The evaluation of interactions between biologically active compounds and other components of the food matrix can be considered as the first action in the investigation of potential benefits of this annual herb. Moreover, updated examples of current and innovative directions in an integrated and multidisciplinary approach are discussed, with particular attention to chemometrics. Among the main effects attributed to okra, its antidiabetic property is the focus. Finally, the use of okra in different fields will be discussed.(undefined)info:eu-repo/semantics/publishedVersio
Confining strings in representations with common -ality
We study the spectrum of confining strings in SU(3) pure gauge theory, by
means of lattice Monte Carlo simulations, using torelon operators in different
representations of the gauge group. Our results provide direct evidence that
the string spectrum is according to predictions based on -ality. Torelon
correlations in the rank-2 symmetric channel appear to be well reproduced by a
two-exponential picture, in which the lowest state is given by the fundamental
string , the heavier string state is such that the ratio
is approximately given by the Casimir ratio , and the torelon has a much smaller overlap with the
lighter fundamental string state.Comment: 7 pages, 2 figure
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