2,929 research outputs found
Freezing in random graph ferromagnets
Using T=0 Monte Carlo and simulated annealing simulation, we study the energy
relaxation of ferromagnetic Ising and Potts models on random graphs. In
addition to the expected exponential decay to a zero energy ground state, a
range of connectivities for which there is power law relaxation and freezing to
a metastable state is found. For some connectivities this freezing persists
even using simulated annealing to find the ground state. The freezing is caused
by dynamic frustration in the graphs, and is a feature of the local
search-nature of the Monte Carlo dynamics used. The implications of the
freezing on agent-based complex systems models are briefly considered.Comment: Published version: 1 reference deleted, 1 word added. 4 pages, 5
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Evaluation of Cerebrospinal Fluid (CSF) in Patients with HIV/Syphilis Co-Infection Followed at Institute of Infectology Emilio Ribas, Brazil
New developments in the forecasting of monthly overnight stays in the North Region of Portugal
The Tourism sector is of strategic importance to the North Region of Portugal and is growing. Forecasting monthly overnight stays in this region is, therefore, a relevant problem. In this paper, we analyze data more recent than those considered in previous studies and use them to develop and compare several forecasting models and methods. We conclude that the best results are achieved by models based on a non-parametric approach not considered so far for these data, the singular spectrum analysis.publishe
Metazoários Parasitos De Lambari Astyanax Altiparanae, Coletados Do Rio Do Peixe, São Paulo, Sudeste Do Brasil
In March 2010, 44 specimens of Astyanax altiparanae Garutti & Britski, 2000, commonly known as “lambari do rabo amarelo”, collected from the Peixe river in the state of São Paulo, Brazil were analyzed. Out of these 44 fishes, 38 had at least one species of metazoan parasite. Fifteen metazoan parasites species were collected and identified: Urocleidoides trinidadensis, Diaphorocleidus kabatai, Diaphorocleidus orthodusus, Diaphorocleidus sp., Urocleidoides sp., Trinibaculum altiparanae, Gyrodactylus sp., Jainus hexops, Contracaecum sp., Procamallanus (Spirocamallanus) inopinatus, Vaigamus sp., Amplexibranchius bryconis, Ergasilus sp., Zonocotyloides haroltravassossi and Henneguya sp. Six species of parasites presented a prevalence of over 10%. Weight and length of fishes didn’t influence the parasitism. All parasites presented an aggregated distribution. The parasite community of Astyanax altiparanae from the Peixe river was characterized as having high richness and low uniformity. © 2016, Universidade Federal de Santa Maria. All rights reserved.46587688
Glauber dynamics in a single-chain magnet: From theory to real systems
The Glauber dynamics is studied in a single-chain magnet. As predicted, a
single relaxation mode of the magnetization is found. Above 2.7 K, the
thermally activated relaxation time is mainly governed by the effect of
magnetic correlations and the energy barrier experienced by each magnetic unit.
This result is in perfect agreement with independent thermodynamical
measurements. Below 2.7 K, a crossover towards a relaxation regime is observed
that is interpreted as the manifestation of finite-size effects. The
temperature dependences of the relaxation time and of the magnetic
susceptibility reveal the importance of the boundary conditions.Comment: Submitted to PRL 10 May 2003. Submitted to PRB 12 December 2003;
published 15 April 200
The low energy limit of the non-commutative Wess-Zumino model
The non-commutative Wess-Zumino model is used as a prototype for studying the
low energy behaviour of a renormalizable non-commutative field theory. We start
by deriving the potential mediating the fermion-fermion and boson-boson
interactions in the non-relativistic regime. The quantum counterparts of these
potentials are afflicted by irdering ambiguities but we show that there exists
an ordering prescription which makes them hermitean. For space/space
noncommutativity it turns out that Majorana fermions may be pictured as rods
oriented perpendicularly to the direction of motion showing a lack of
localituy, while bosons remain insensitive to the effects of noncommutativity.
For time/space noncommutativity bosopns and fermions can be regarded as rods
oriented along the direction of motion. For both cases of noncommutativity the
scattering state described scattered waves, with at least one wave having
negative time delay signalizing the underlying nonlocality. The superfield
formulation of the model is used to compute the corresponding effective action
in the one- and two-loop approximations. In the case of time/space
noncommutativity, unitarity is violated in the relativistic regime. However,
this does not preclude the existence of the unitary low energy limit.Comment: 14 pages, 2 figures, minor correction
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