5,961 research outputs found
Scaling above the upper critical dimension in Ising Models
We rederive the finite size scaling formula for the apparent critical
temperature by using Mean Field Theory for the Ising Model above the upper
critical dimension. We have also performed numerical simulations in five
dimensions and our numerical data are in a good agreement with the Mean Field
theoretical predictions, in particular, with the finite size exponent of the
connected susceptibility and with the value of the Binder cumulant.Comment: 9 pages and 3 figures, available at
http://chimera.roma1.infn.it/index_papers_complex.htm
Generalized off-equilibrium fluctuation-dissipation relations in random Ising systems
We show that the numerical method based on the off-equilibrium
fluctuation-dissipation relation does work and is very useful and powerful in
the study of disordered systems which show a very slow dynamics. We have
verified that it gives the right information in the known cases (diluted
ferromagnets and random field Ising model far from the critical point) and we
used it to obtain more convincing results on the frozen phase of
finite-dimensional spin glasses. Moreover we used it to study the Griffiths
phase of the diluted and the random field Ising models.Comment: 20 pages, 10 figures, uses epsfig.sty. Partially presented at
StatPhys XX in a talk by one of the authors (FRT). Added 1 reference in the
new versio
Integrability of Stochastic Birth-Death processes via Differential Galois Theory
Stochastic birth-death processes are described as continuous-time Markov
processes in models of population dynamics. A system of infinite, coupled
ordinary differential equations (the so-called master equation) describes the
time-dependence of the probability of each system state. Using a generating
function, the master equation can be transformed into a partial differential
equation. In this contribution we analyze the integrability of two types of
stochastic birth-death processes (with polynomial birth and death rates) using
standard differential Galois theory. We discuss the integrability of the PDE
via a Laplace transform acting over the temporal variable. We show that the PDE
is not integrable except for the (trivial) case in which rates are linear
functions of the number of individuals
Deep learning methods applied to digital elevation models: state of the art
Deep Learning (DL) has a wide variety of applications in various
thematic domains, including spatial information. Although with
limitations, it is also starting to be considered in operations
related to Digital Elevation Models (DEMs). This study aims to
review the methods of DL applied in the field of altimetric spatial
information in general, and DEMs in particular. Void Filling (VF),
Super-Resolution (SR), landform classification and hydrography
extraction are just some of the operations where traditional methods
are being replaced by DL methods. Our review concludes
that although these methods have great potential, there are
aspects that need to be improved. More appropriate terrain information
or algorithm parameterisation are some of the challenges
that this methodology still needs to face.Functional Quality of Digital Elevation Models in Engineering’ of the State Agency Research of SpainPID2019-106195RB- I00/AEI/10.13039/50110001103
Anthropometric measures as predictive indicators of metabolic risk in a population of “holy week costaleros”
Preventive measures are a priority in those groups that perform intense physical efforts without physical preparation and that can also be overweight or obese. One of the groups that reflect these characteristics is the costaleros of the Holy Week of Andalusia, Spain. This paper aims to describe the effect of obesity on blood pressure. A descriptive cross-sectional study was conducted on 101 costaleros. The anthropometric measures were determined through segmental impedance. Cardiac
recovery and anaerobic power were measured through the Ruffier–Dickson test and the Abalakov test, respectively. Blood pressure was measured when the individuals were at rest. The Kruskal–Wallis test was applied for of continuous parameters and the X2 test for dichotomous measures. Binary logistic regression models were used for the subsequent analysis with R-square and Receiver Operating Characteristic (ROC) curves. The average population was 28 years of age, 173.7 cm tall, and 82.59 Kg weigh. The excess of body fat was 11.27 Kg and Body Mass Index was 27.33 Kg/m2. 72.3% showed abnormal blood pressure and 68.2% were overweight. 32.7% had a waist-hip ratio higher than 0.94. The probability of presenting abnormal blood pressure was higher among the subjects whose fat content was higher and muscle content was lower
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