14,571 research outputs found
The out-equilibrium 2D Ising spin glass: almost, but not quite, a free-field theory
We consider the spatial correlation function of the two-dimensional Ising
spin glass under out-equilibrium conditions. We pay special attention to the
scaling limit reached upon approaching zero temperature. The field-theory of a
non-interacting field makes a surprisingly good job at describing the spatial
shape of the correlation function of the out-equilibrium Edwards-Anderson Ising
model in two dimensions.Comment: 20 pages + 5 Figure
Tempering Dynamics and Relaxation Times in the Ising Model
We discuss the tempering Monte Carlo method, and its critical slowing down in
the Ising model. We show that at the tempering does not change the
critical slowing down exponent . We also discuss the exponential slowing
down for the transition from the plus to the minus state in the cold phase, and
we show that tempering reduces it to a power law slowing down. We discuss the
relation of the flip-flop rate to the surface tension for the local dynamical
schemes.Comment: 10 pages, compressed ps-file (uufiles
Microcanonical finite-size scaling in specific heat diverging 2nd order phase transitions
A Microcanonical Finite Site Ansatz in terms of quantities measurable in a
Finite Lattice allows to extend phenomenological renormalization (the so called
quotients method) to the microcanonical ensemble. The Ansatz is tested
numerically in two models where the canonical specific-heat diverges at
criticality, thus implying Fisher-renormalization of the critical exponents:
the 3D ferromagnetic Ising model and the 2D four-states Potts model (where
large logarithmic corrections are known to occur in the canonical ensemble). A
recently proposed microcanonical cluster method allows to simulate systems as
large as L=1024 (Potts) or L=128 (Ising). The quotients method provides
extremely accurate determinations of the anomalous dimension and of the
(Fisher-renormalized) thermal exponent. While in the Ising model the
numerical agreement with our theoretical expectations is impressive, in the
Potts case we need to carefully incorporate logarithmic corrections to the
microcanonical Ansatz in order to rationalize our data.Comment: 13 pages, 8 figure
Comment on "Evidence of Non-Mean-Field-Like Low-Temperature Behavior in the Edwards-Anderson Spin-Glass Model"
A recent interesting paper [Yucesoy et al. Phys. Rev. Lett. 109, 177204
(2012), arXiv:1206:0783] compares the low-temperature phase of the 3D
Edwards-Anderson (EA) model to its mean-field counterpart, the
Sherrington-Kirkpatrick (SK) model. The authors study the overlap distributions
P_J(q) and conclude that the two models behave differently. Here we notice that
a similar analysis using state-of-the-art, larger data sets for the EA model
(generated with the Janus computer) leads to a very clear interpretation of the
results of Yucesoy et al., showing that the EA model behaves as predicted by
the replica symmetry breaking (RSB) theory.Comment: Version accepted for publication in PRL. 1 page, 1 figur
Living in a transient world: ICP-MS reinvented via time-resolved analysis for monitoring single events
After 40 years of development, inductively coupled plasma-mass spectrometry (ICP-MS) can hardly be considered as a novel technique anymore. ICP-MS has become the reference when it comes to multi-element bulk analysis at (ultra)trace levels, as well as to isotope ratio determination for metal(loid)s. However, over the last decade, this technique has managed to uncover an entirely new application field, providing information in a variety of contexts related to the individual analysis of single entities (e.g., nanoparticles, cells, or micro/nanoplastics), thus addressing new societal challenges. And this profound expansion of its application range becomes even more remarkable when considering that it has been made possible in an a priori simple way: by providing faster data acquisition and developing the corresponding theoretical substrate to relate the time-resolved signals thus obtained with the elemental composition of the target entities. This review presents the underlying concepts behind single event-ICP-MS, which are needed to fully understand its potential, highlighting key areas of application (e.g., single particle-ICP-MS or single cell-ICP-MS) as well as of future development (e.g., micro/nanoplastics)
An experiment-oriented analysis of 2D spin-glass dynamics: a twelve time-decades scaling study
Recent high precision experimental results on spin-glass films ask for a
detailed understanding of the domain-growth dynamics of two-dimensional spin
glasses. To achieve this goal, we numerically simulate the out-equilibrium
dynamics of the Ising spin glass for a time that spans close to twelve orders
of magnitude (from picoseconds to order of a second), in systems large enough
to avoid finite-size effects. We find that the time-growth of the size of the
glassy domains is excellently described by a single scaling function. A single
time-scale controls the dynamics. diverges upon approaching
the critical point. The divergence of is Arrhenius-like,
with a barrier height that depends very mildly on temperature. The growth of
this barrier-height is best described by critical dynamics. As a side product
we obtain an impressive confirmation of universality of the equilibrium
behavior of two-dimensional spin-glasses.Comment: 21 pages, 9 figures. Updated references. Added DOI and Journal re
Medical Students’ Perception Towards the COVID-19 Pandemic in Mexico: Distance Learning, Assisting Hospitals, and Vaccination
Background: Mexico has been one of the most affected countries by the COVID-19 pandemic. Its health workers are playing a substantial role, but they are suffering from a high mortality rate, which highlights the need of vaccinating them before any other population. Medical interns have reduced their practices, some continue to assist clinical rotations without the protective equipment, and they are not being considered for vaccination. We wanted to determine the attitude of medical students and interns towards distance learning, assisting hospitals, and vaccination.
Methods: We conducted a paired survey of a cohort of medical students who were evaluated twice, in June 2020 and in December 2020, using an online survey (32-online questions) to assess their perception of the pandemic.
Results: We collected the response of 384 students in the summer period and 331 in the winter period; the majority were women from non-clinical semesters, and the median age of response was 21 years old (IQR 19 – 22). We found that the percentage of acceptance for vaccination was 95.6% in the summer and 93.7% in the winter, a remarkable acceptance in both periods. The percentage of students who manifested having someone close to them with symptoms suggestive of COVID-19 was 38.5% in the summer, showing an increase to 77.6% in the winter.
Conclusion: We observed that medical students had a positive attitude towards vaccination and that the probable COVID-19 cases among them have increased in just a few months
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