1,436 research outputs found
On the Use of Optimized Monte Carlo Methods for Studying Spin Glasses
We start from recently published numerical data by Hatano and Gubernatis
cond-mat/0008115 to discuss properties of convergence to equilibrium of
optimized Monte Carlo methods (bivariate multi canonical and parallel
tempering). We show that these data are not thermalized, and they lead to an
erroneous physical picture. We shed some light on why the bivariate multi
canonical Monte Carlo method can fail.Comment: 6 pages, 5 eps figures include
Replica Symmetry Breaking in Short-Range Spin Glasses: Theoretical Foundations and Numerical Evidences
We discuss replica symmetry breaking (RSB) in spin glasses. We update work in
this area, from both the analytical and numerical points of view. We give
particular attention to the difficulties stressed by Newman and Stein
concerning the problem of constructing pure states in spin glass systems. We
mainly discuss what happens in finite-dimensional, realistic spin glasses.
Together with a detailed review of some of the most important features, facts,
data, and phenomena, we present some new theoretical ideas and numerical
results. We discuss among others the basic idea of the RSB theory, correlation
functions, interfaces, overlaps, pure states, random field, and the dynamical
approach. We present new numerical results for the behaviors of coupled
replicas and about the numerical verification of sum rules, and we review some
of the available numerical results that we consider of larger importance (for
example, the determination of the phase transition point, the correlation
functions, the window overlaps, and the dynamical behavior of the system).Comment: 48 pages, 21 figures. v2: the published versio
Comment on "Ising Spin Glasses in a Magnetic Field"
In ref. cond-mat/9811419 Houdayer and Martin analyze the T=0 3d EA spin glass
with a magnetic field . By using a new, powerful method, they determine an
effective critical field as a function of the lattice size . They use
their results to deduce that the model is behaving like in the droplet approach
and not like the mean-field theory. We show here, by using some unpublished
data, that this very interesting method and numerical results are completely
compatible with the behavior implied by the Replica Symmetry Breaking theory.Comment: One page comment about ref. cond-mat/9811419, including two eps
figure
Laser and microwave spectroscopy of even-parity Rydberg states of neutral ytterbium and Multichannel Quantum Defect Theory analysis
New measurements of high-lying even parity and
levels of neutral Yb are presented in this paper.
Spectroscopy is performed by a two-step laser excitation from the ground state
, and the Rydberg levels are detected by using the
field ionization method. Additional two-photon microwave spectroscopy is used
to improve the relative energy accuracy where possible. The spectroscopic
measurements are complemented by a multichannel quantum defect theory (MQDT)
analysis for the J=0 and the two-coupled J=2 even parity series. We compare our
results with the previous analysis of Aymar {\it{et al}} \cite{Aymar_1980} and
analyze the observed differences. From the new MQDT models, a revised value for
the first ionization limit cm is proposed.Comment: 15 pages, 3 figure
Comment on "Evidence for the Droplet/Scaling Picture of Spin Glasses"
In a recent letter Moore et al. claim to exhibit evidence for a
non-mean-field behavior of the Ising spin glass. We show that their claim
is insubstantial, and by analyzing in detail the behavior of the
Migdal-Kadanoff approximation (MKA) as compared to the behavior of the
Edwards-Anderson (EA) spin glass we find further evidence of a mean-field like
behavior of the spin glass.Comment: 1 page comment including one postscript figur
Pengaruh Dimensi Pengembangan Pengetahuan, Peningkatan Ketrampilan Baru, Dan Kesadaran Masyarakat Terhadap Kinerja Maqasid
Konsep maqasid syariah bertujuan untuk mendidik individu, menciptakan keadilan dan kemaslahatan. Untuk mencapai tujuan mendidik individu, dilakukan suatu pengukuran melalui elemen pendidikan, penelitian, pelatihan dan publikasi. Penelitian ini bertujuan untuk menganalisis pengaruh dimensi pengembangan pengetahuan, peningkatkan keterampilan baru,dan kesadaran masyarakat terhadap kinerja maqasid syariah ditinjau dari tujuan mendidik individu. Dan untuk mengetahui perbedaan kinerja maqasid perbankan syariah di Indonesia dan Malaysia. Sampel pada penelitian ini adalah lima Bank Umum Syariah (BUS) di Indonesia dan lima perbankan syariah di Malaysia. Teknik penyampelan yang digunakan adalah teknik purposive sampling. Untuk menguji pengaruh elemen-elemen terhadap kinerja maqasid syariah, dilakukan dengan pengujian analisis regresi berganda, dan uji beda independent sample t test digunakan untuk menguji perbedaan kinerja maqasid perbankan syariah di Indonesia dan Malaysia. Berdasarkan hasil analisis, ditemukan bahwa terdapat pengaruh positif pengembangan pengetahuan, peningkatkan keterampilan baru, menciptakan kesadaran masyarakat akan keberadaan entitas syariah terhadap maqasid syariah. Kemudian, terdapat perbedaan kinerja maqasid perbankan syariah di Indonesia dan Malaysia
4D Spin Glasses in Magnetic Field Have a Mean Field like Phase
By using numerical simulations we show that the 4D Edwards Anderson
spin glass in magnetic field undergoes a mean field like phase transition. We
use a dynamical approach: we simulate large lattices (of volume ) and work
out the behavior of the system in limit where both and go to infinity,
but where the limit is taken first. By showing that the dynamic
overlap converges to a value smaller than the static one we exhibit replica
symmetry breaking. The critical exponents are compatible with the ones obtained
by mean field computations.Comment: Physrev format, 5 ps figures include
The mean field infinite range p=3 spin glass: equilibrium landscape and correlation time scales
We investigate numerically the dynamical behavior of the mean field 3-spin
spin glass model: we study equilibrium dynamics, and compute equilibrium time
scales as a function of the system size V. We find that for increasing volumes
the time scales increase like . We also present an
accurate study of the equilibrium static properties of the system.Comment: 6 pages, 9 figure
Diaminodiphenylmethane Sensitization in north-eastern Italy from 1996 to 2012
BACKGROUND:
4,4'-Diaminodiphenylmethane (DDM) is an aromatic amine used as a hardener, insulator and anticorrosive. Exposure implies risk of being sensitized and developing contact dermatitis.
OBJECTIVE:
The aim of this study was to determine the occurrence of contact sensitization to DDM among patients with contact dermatitis and the role of occupational exposure.
PATIENTS AND METHODS:
From 1996 to 2012, 24 056 consecutive patients with suspected allergic contact dermatitis were patch tested in north-eastern Italy. Individual characteristics were collected through a standardized questionnaire in eight departments of dermatology and occupational medicine.
RESULTS:
The overall prevalence of DDM sensitization was 2.5% (n = 599) with a decreasing trend in considered years. Trieste area had the higher prevalence of sensitization (3.2%). Mechanics and chemical industry workers had a significant higher risk of being sensitized to DDM.
CONCLUSION:
DDM sensitization is decreasing in years and is associated with some occupational exposures
Overlap Among States at Different Temperatures in the SK Model
We discuss the issue of temperature chaos in the Sherrington--Kirkpatrick
spin glass mean field model. We numerically compute probability distributions
of the overlap among (equilibrium) configurations at two different values of
the temperature, both in the spin glass phase. The situation on our medium size
systems is clearly non-chaotic, but a weak form of chaos could be emerging on
very large lattices.Comment: 4 pages in aps format including 8 ps figures. Small change
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