Nonextensive thermostatistics and the H theorem

The kinetic foundations of Tsallis' nonextensive thermostatistics are investigated through Boltzmann's transport equation approach. Our analysis follows from a nonextensive generalization of the "molecular chaos hypothesis." For q>0, the q-transport equation satisfies an H theorem based on Tsallis entropy. It is also proved that the collisional equilibrium is given by Tsallis' q-nonextensive velocity distribution.     

Ionic conduction and thermal properties of poly(ethylene oxide) - Er (CF3SO3)3 films

Measurements of electrical conductivity and thermal behaviour have been carried out on polymer electrolyte films obtained by the addition of erbium triflate to poly(ethylene oxide), PEO. Homogeneous electrolyte samples were prepared by using solvent casting and hot-pressing techniques to produce films with a composition defined by the general formula (EO)_nEr(CF₃SO₃)₃, where n lies between 3 and 150. This electrolyte system was found to behave in a manner broadly similar to other trivalent salt containing polymer electrolytes, however, in contrast to previously studied lanthanide systems, a salt - polymer complex crystallized after prolonged annealing of salt rich compositions at room temperature. Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10 – 16, 1995     

Epidemic spreading in a scale-free network of regular lattices

The susceptible-infected-susceptible (SIS) epidemics in a scale-free network in which each node is a square lattice itself is investigated through large-scale computer simulations. The model combines a local contact process among individuals in a node (or city) with stochastic long-range infections due to people traveling between cities interconnected by the national transportation scale-free network. A nonzero epidemic threshold is found and it is approached with a power-law behavior by the density of infected individuals, as observed in the small-world network of Watts and Strogatz. Also, the epidemic propagation follows a 1/f$1/f$, hierarchical dynamics from the highly connected square lattices to the smaller degree nodes in outbreaks with sizes distributed accordingly a Gaussian function.     

A 119Sn Mössbauer Spectroscopic Investigation of Tin Complexes with Amidines

Several novel tin(IV) adducts of amidines, [SnClPh₃L], [SnCl₂Ph₂L] and [SnBr₄L] {L=N,N-diphenylacetamidine (Hdpac) or N,N-diphenylbenzamidine (Hdpba)}, were prepared and investigated by Mössbauer spectroscopy which was an important tool for the elucidation of bonding and structural features. The resulting Mössbauer data also led to the conclusion that the tin(IV) centre for the adduct [SnClPh₃L] is pentacoordinated in a trigonal bipyramidal arrangement and hexacoordinated for [SnCl₂Ph₂L] and [SnBr₄L] in a geometric patterns of an octahedral. The amidines act as monodentate ligands to the metal centre for the former and bidentate for the latter.     

Short-Term Therapeutic Trial of Proton Pump Inhibitors in Suspected Extraesophageal Reflux

Pharyngoesophageal gastric acid reflux is thought to initiate chronic posterior laryngitis. The gold standard for measuring gastric reflux is dual-channel 24-hour pH monitoring. This is a time-consuming, inconvenient, expensive method that is not available in all areas. New therapeutic regimes that make use of proton pump inhibitors (PPIs) have proven to be therapeutically efficient for control of acid reflux. Twenty-four consecutive patients with chronic voice disorders and signs of posterior laryngitis were selected for therapy. Twenty-four hour pH monitoring was performed independently before the therapy. The trial therapy consisted of all patients receiving pantoprazole, 40 mg once daily for 6 weeks. Immediately following the therapy a statistically significant (p < 0.05) improvement was observed in all patients. This improvement was analyzed retrospectively by comparison with the results of 24-hour pH monitoring. In 71% of the patients the 24-hour pH-monitoring gave a positive result showing a high number of patients with extraesophageal reflux in our study group. Patients with positive results of pH-monitoring responded in a statistically significant manner (p < 0.05) to the pantoprazole therapy, whereas those patients without detected reflux did not. A 3-month follow-up of the patients with a positive result of the pH-monitoring confirmed the improvement. No patients reported adverse effects. A 6-week treatment with pantoprazole can be clinically justified. It helps to save time and reduce costs, allows for selection of reflux-negative patients for alternative therapy, and may prevent inadequate treatment of patients with false-negative pH monitoring. Twenty-four hour pH monitoring is still recommended for patients unresponsive to this trial therapy.     

Confirming the lattice contraction in CdSe nanocrystals grown in a glass matrix by Raman scattering

This work gives the evidence of the lattice contraction in CdSe nanocrystals (NCs) grown in a glass matrix. The CdSe NCs were investigated by atomic force microscopy (AFM), optical absorption (OA), and Raman spectroscopy. The average size of CdSe NCs can be estimated by AFM images. Using the OA spectra and the effective‐mass approximation, it was also possible to estimate the average sizes of CdSe NCs, which agree very well with the AFM data. These results showed that the CdSe NCs grow with increasing time of heat treatment. The blue shift of the longitudinal optical (LO) modes and surface optical (SO) phonon modes with an increase in the average radius of the NCs, shown in the Raman spectra, was explained by the lattice contraction in CdSe NCs caused by thermodynamic interactions at the interface with the host glass matrix. Copyright © 2010 John Wiley & Sons, Ltd.     

Conformal Klein-Gordon Equations and Quasinormal Modes

Using conformal coordinates associated with conformal relativity—associated with de Sitter spacetime homeomorphic projection into Minkowski spacetime—we obtain a conformal Klein-Gordon partial differential equation, which is intimately related to the production of quasi-normal modes (QNMs) oscillations, in the context of electromagnetic and/or gravitational perturbations around, e.g., black holes. While QNMs arise as the solution of a wave-like equation with a Pöschl-Teller potential, here we deduce and analytically solve a conformal ‘radial’ d’Alembert-like equation, from which we derive QNMs formal solutions, in a proposed alternative to more completely describe QNMs. As a by-product we show that this ‘radial’ equation can be identified with a Schrödinger-like equation in which the potential is exactly the second Pöschl-Teller potential, and it can shed some new light on the investigations concerning QNMs.     

Nonlinear spectrum effect on the coherent control of molecular systems

This work demonstrates that the detuning of the fs-laser spectrum from the two-photon absorption band of organic materials can be used to reach further control of the two-photon absorption by pulse spectral phase manipulation. We investigate the coherent control of the two-photon absorption in imidazole-thiophene core compounds presenting distinct two-photon absorption spectra. The coherent control, performed using pulse phase shaping and genetic algorithm, exhibited different growth rates for each sample. Such distinct trends were explained by calculating the two-photon absorption probability considering the intrapulse interference mechanism, taking into account the two-photon absorption spectrum of the samples. Our results indicate that tuning the relative position between the nonlinear absorption and the pulse spectrum can be used as a novel strategy to optimize the two-photon absorption in broadband molecular systems.     

BPS solutions to a generalized Maxwell–Higgs model

We look for topological BPS solutions of an Abelian Maxwell–Higgs theory endowed by non-standard kinetic terms to both gauge and scalar fields. Here, the non-usual dynamics are controlled by two positive functions, G(|ϕ|) and w(|ϕ|), which are related to the self-dual scalar potential V(|ϕ|) of the model by a fundamental constraint. The numerical results we found present interesting new features, and contribute to the development of the recent issue concerning the study of generalized models and their applications.