α\alpha- and β\beta- Relaxation Dynamics of a fragile plastic crystal

We present a thorough dielectric investigation of the relaxation dynamics of plastic crystalline Freon112, which exhibits freezing of the orientational degrees of freedom into a glassy crystal below 90 K. Among other plastic crystals, Freon112 stands out by being relatively fragile within Angell's classification scheme and by showing an unusually strong $\beta$-relaxation. Comparing the results to those on Freon112a, having only a single molecular conformation, points to the importance of the presence of two molecular conformations in Freon112 for the explanation of its unusual properties.Comment: 17 pages, 6 figure

Injection statistics simulator for dynamic analysis of noise in mesoscopic devices

We present a model for electron injection from thermal reservoirs which is applied to particle simulations of one-dimensional mesoscopic conductors. The statistics of injected carriers is correctly described from nondegenerate to completely degenerate conditions. The model is validated by comparing Monte Carlo simulations with existing analytical results for the case of ballistic conductors. An excellent agreement is found for average and noise characteristics, in particular, the fundamental unities of electrical and thermal conductances are exactly reproduced.Comment: 4 pages, revtex, 4 PS figures, accepted Semicond. Sci. Techno

Dynamic heterogeneity in the glass-like monoclinic phases of some halogen methane compounds

In this work we study the heterogeneity of the dynamics on the low-temperature monoclinic phases of the simple molecular glassy systems CBrnCl4−nCBrnCl4−n, n = 0, 1, 2. In these systems the disorder comes exclusively from reorientational jumps mainly around the C3 molecular axes. The different time scales are determined by means of the analysis of the spin-lattice relaxation time obtained through Nuclear Quadrupole Resonance (NQR) technique. Results are compared with those obtained from dielectric spectroscopy, from which two α- and β-relaxation times appear. NQR results enable us to ascribe with no doubt that the existence of two relaxations is due to dynamical heterogeneities which are the consequence of the different molecular surroundings of the molecules in the asymmetric unit cell of systems here studied.Fil: Zuriaga, Mariano Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Perez, S. C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Pardo, L. C.. Universidad Politecnica de Catalunya; EspañaFil: Tamarit, J. L.. Universidad Politecnica de Catalunya; Españ

An exploratory canonical analysis approach for multinomial populations based on the ϕ\phi-divergence measure

summary:In this paper we consider an exploratory canonical analysis approach for multinomial population based on the $\phi$-divergence measure. We define the restricted minimum $\phi$-divergence estimator, which is seen to be a generalization of the restricted maximum likelihood estimator. This estimator is then used in $\phi$-divergence goodness-of-fit statistics which is the basis of two new families of statistics for solving the problem of selecting the number of significant correlations as well as the appropriateness of the model