983 research outputs found
Energy Landscape Statistics of the Random Orthogonal Model
The Random Orthogonal Model (ROM) of Marinari-Parisi-Ritort [MPR1,MPR2] is a
model of statistical mechanics where the couplings among the spins are defined
by a matrix chosen randomly within the orthogonal ensemble. It reproduces the
most relevant properties of the Parisi solution of the Sherrington-Kirckpatrick
model. Here we compute the energy distribution, and work out an extimate for
the two-point correlation function. Moreover, we show exponential increase of
the number of metastable states also for non zero magnetic field.Comment: 23 pages, 6 figures, submitted to J. Phys.
PCV29: PERSISTENCY OF TREATMENT IN PATIENTS INITIATED ON FIVE DIFFERENT CLASSES OF ANTIHYPERTENSIVE THERAPY: A PHARMACO-UTILIZATION AND PHARMACO-ECONOMIC ANALYSIS
PCV76 Standard Costs and Resources Allocation in Attainment of Target Lipid Levels among Experienced Statin Users: Results From the STAR Study (Statins Target Assessment in Real Practice)
Statistics of energy levels and zero temperature dynamics for deterministic spin models with glassy behaviour
We consider the zero-temperature dynamics for the infinite-range, non
translation invariant one-dimensional spin model introduced by Marinari, Parisi
and Ritort to generate glassy behaviour out of a deterministic interaction. It
is shown that there can be a large number of metatastable (i.e., one-flip
stable) states with very small overlap with the ground state but very close in
energy to it, and that their total number increases exponentially with the size
of the system.Comment: 25 pages, 8 figure
Thermodynamical Limit for Correlated Gaussian Random Energy Models
Let \{E_{\s}(N)\}_{\s\in\Sigma_N} be a family of centered
unit Gaussian random variables defined by the covariance matrix of
elements \displaystyle c_N(\s,\tau):=\av{E_{\s}(N)E_{\tau}(N)}, and H_N(\s)
= - \sqrt{N} E_{\s}(N) the corresponding random Hamiltonian. Then the quenched
thermodynamical limit exists if, for every decomposition , and all
pairs (\s,\t)\in \Sigma_N\times \Sigma_N: c_N(\s,\tau)\leq \frac{N_1}{N}
c_{N_1}(\pi_1(\s),\pi_1(\tau))+ \frac{N_2}{N} c_{N_2}(\pi_2(\s),\pi_2(\tau))
where \pi_k(\s), k=1,2 are the projections of \s\in\Sigma_N into
. The condition is explicitly verified for the
Sherrington-Kirckpatrick, the even -spin, the Derrida REM and the
Derrida-Gardner GREM models.Comment: 15 pages, few remarks and two references added. To appear in Commun.
Math. Phy
Ground states for a class of deterministic spin models with glassy behaviour
We consider the deterministic model with glassy behaviour, recently
introduced by Marinari, Parisi and Ritort, with \ha\ , where is the discrete sine Fourier transform. The
ground state found by these authors for odd and prime is shown to
become asymptotically dege\-ne\-ra\-te when is a product of odd primes,
and to disappear for even. This last result is based on the explicit
construction of a set of eigenvectors for , obtained through its formal
identity with the imaginary part of the propagator of the quantized unit
symplectic matrix over the -torus.Comment: 15 pages, plain LaTe
Egorov property in perturbed cat map
We study the time evolution of the quantum-classical correspondence (QCC) for
the well known model of quantised perturbed cat maps on the torus in the very
specific regime of semi-classically small perturbations. The quality of the QCC
is measured by the overlap of classical phase-space density and corresponding
Wigner function of the quantum system called quantum-classical fidelity (QCF).
In the analysed regime the QCF strongly deviates from the known general
behaviour in particular it decays faster then exponential. Here we study and
explain the observed behavior of the QCF and the apparent violation of the QCC
principle.Comment: 12 pages, 7 figure
Deterministic spin models with a glassy phase transition
We consider the infinite-range deterministic spin models with Hamiltonian
, where is the quantization of a
chaotic map of the torus. The mean field (TAP) equations are derived by summing
the high temperature expansion. They predict a glassy phase transition at the
critical temperature .Comment: 8 pages, no figures, RevTex forma
Health Care Resource Utilization Costs Related to Anaemia Management in Chronic Kidney Disease Non-Dialysed Patients: A Retrospective Clinical and Administrative Database Analysis
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Universality in the flooding of regular islands by chaotic states
We investigate the structure of eigenstates in systems with a mixed phase
space in terms of their projection onto individual regular tori. Depending on
dynamical tunneling rates and the Heisenberg time, regular states disappear and
chaotic states flood the regular tori. For a quantitative understanding we
introduce a random matrix model. The resulting statistical properties of
eigenstates as a function of an effective coupling strength are in very good
agreement with numerical results for a kicked system. We discuss the
implications of these results for the applicability of the semiclassical
eigenfunction hypothesis.Comment: 11 pages, 12 figure
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