On the origin of ultrametricity

In this paper we show that in systems where the probability distribution of the the overlap is non trivial in the infinity volume limit, the property of ultrametricity can be proved in general starting from two very simple and natural assumptions: each replica is equivalent to the others (replica equivalence or stochastic stability) and all the mutual information about a pair of equilibrium configurations is encoded in their mutual distance or overlap (separability or overlap equivalence).Comment: 13 pages, 1 figur

Sequential evacuation strategy for multiple rooms toward the same means of egress

This paper examines different evacuation strategies for systems where several rooms evacuate trough the same means of egress, using microscopic pedestrian simulation.As a case study, a medium-rise office building is considered. It was found that the standard strategy, whereby the simultaneous evacuation of all levels is performed, can be improved by a sequential evacuation, beginning with the lowest floor and continuing successively with each one of the upper floors after a certain delay. The importance of the present research is that it provides the basis for the design and implementation of new evacuation strategies and alarm systems that could significantly improve the evacuation of multiple rooms trough a common means of escape.Comment: 8 pages, 4 figure

Smooth Muscle Myosin Heavy Chain Isoform Distribution in the Swine Stomach

To evaluate the distribution of smooth muscle myosin heavy chain isoforms (SMB, with head insert), we examined frozen sections from the various regions of swine stomachs using isoform-specific antibodies. We previously reported variable SMB myosin heavy chain (MHC) expression in stomach cells that correlates with unloaded shortening velocities. This is consistent with the generalization of tonic fundic muscle having low expression and phasic antral muscle having high expression of the SMB MHC isoform. Using immunohistochemistry (IHC), we show a progression of the SMB MHC from very low immunoreactivity in the fundus to very intense immunoreactivity in the antrum. In the body, the average level of SMB MHC immunoreactivity lies between that of the antrum and fundus. Intercellular heterogeneity was observed in all stomach regions to a similar extent. However, the intercellular range in SMB MHC immunoreactivity decreases from fundus to antrum. All stomach regions show isolated pockets or clusters of cells with similar SMB MHC immunoreactivity. There is a non-uniform intracellular immunoreactivity in SMB MHC, with many cells showing greater-intensity staining of SMB MHC in their cell peripheries. This information may prove useful in helping to elucidate possible unique physiological roles of SMB MHC

On the Effects of Changing the Boundary Conditions on the Ground State of Ising Spin Glasses

We compute and analyze couples of ground states of 3D spin glass systems with the same quenched noise but periodic and anti-periodic boundary conditions for different lattice sizes. We discuss the possible different behaviors of the system, we analyze the average link overlap, the probability distribution of window overlaps (among ground states computed with different boundary conditions) and the spatial overlap and link overlap correlation functions. We establish that the picture based on Replica Symmetry Breaking correctly describes the behavior of 3D Spin Glasses.Comment: 25 pages with 11 ps figures include

Small Window Overlaps Are Effective Probes of Replica Symmetry Breaking in 3D Spin Glasses

We compute numerically small window overlaps in the three dimensional Edwards Anderson spin glass. We show that they behave in the way implied by the Replica Symmetry Breaking Ansatz, that they do not qualitatively differ from the full volume overlap and do not tend to a trivial function when increasing the lattice volume. On the contrary we show they are affected by small finite volume effects, and are interesting tools for the study of the features of the spin glass phase.Comment: 9 pages plus 5 figure

The Overlap between Headache and Epilepsy in the Light of Recent Advances in Medical Genetics

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On Spin-Glass Complexity

We study the quenched complexity in spin-glass mean-field models satisfying the Becchi-Rouet-Stora-Tyutin supersymmetry. The outcome of such study, consistent with recent numerical results, allows, in principle, to conjecture the absence of any supersymmetric contribution to the complexity in the Sherrington-Kirkpatrick model. The same analysis can be applied to any model with a Full Replica Symmetry Breaking phase, e.g. the Ising $p$-spin model below the Gardner temperature. The existence of different solutions, breaking the supersymmetry, is also discussed.Comment: 4 pages, 2 figures; Text changed in some parts, typos corrected, Refs. [17],[21] and [22] added, two Refs. remove

A numerical study of the overlap probability distribution and its sample-to-sample fluctuations in a mean-field model

In this paper we study the fluctuations of the probability distributions of the overlap in mean field spin glasses in the presence of a magnetic field on the De Almeida-Thouless line. We find that there is a large tail in the left part of the distribution that is dominated by the contributions of rare samples. Different techniques are used to examine the data and to stress on different aspects of the contribution of rare samples.Comment: 13 pages, 11 figure