Ergodic parameters and dynamical complexity

Using a cocycle formulation, old and new ergodic parameters beyond the Lyapunov exponent are rigorously characterized. Dynamical Renyi entropies and fluctuations of the local expansion rate are related by a generalization of the Pesin formula. How the ergodic parameters may be used to characterize the complexity of dynamical systems is illustrated by some examples: clustering and synchronization, self-organized criticality and the topological structure of networks.     

Electrochemical Detection of Guanine‐methylation Using Glassy Carbon Electrode

This work presents a study of the electrochemical oxidation of 7‐methylguanine (7‐mGua) in aqueous solution at glassy carbon electrode by cyclic voltammetry, differential pulse voltammetry, square wave voltammetry and electrochemical impedance spectrometry. The anodic behaviour of 7‐mGua was compared with the electro‐oxidation of guanine and 7‐methylguanosine. The results demonstrated that the methyl and ribose groups are not electroactive but strongly influence the oxidation mechanism of these species. The oxidation of 7‐mGua occurred in a single pH‐dependent step, with the withdrawal of two electrons and two protons of C8, to form 8‐oxo‐7‐methylguanine, while the electro‐oxidation of 7‐methylguanosine also occurred in a single pH‐dependent step, however, with the withdrawal of one electron and one proton of C8 to form a hydroxylated product, since its oxidation to 8‐oxo‐7‐methylguanosine is hindered by the presence of the pendant groups. In addition, the oxidation of 7‐mGua was investigated in the presence of DNA and DNA‐bases, leading to the conclusion that the formation of 7‐mGua, from an interaction of DNA with an alkylating agent, would cause an increase on the deoxyguanosine peak current of the DNA‐biosensor, with no interference of any free DNA bases, which demonstrated that DNA‐electrochemical biosensors find application on detecting DNA methylation, opening a new avenue for applications of DNA biosensors.     

Lagrangian description of the radiation damping

We present a Lagrangian formalism to the dissipative system of a charge interacting with its own radiation field, which gives rise to the radiation damping [W. Heitler, The Quantum Theory of Radiation, third ed., Dover, New York, 1970; J.D. Jackson, Classical Electrodynamics, second ed., Wiley, New York, 1975 (Chapters 14, 17); G.N. Plass, Rev. Mod. Phys. 33 (1961) 37], by the indirect representation doubling the phase-space dimensions.     

Reconstruction of dynamics from the vacuum in lattice theories

The Coester-Haag scheme to define the dynamics from the vacuum is applied to lattice theories. As an example the reconstruction algorithm is carried out for two trial ground states. The reconstruction approach may by itself define the theory or, when coupled with a variational calculation and a fixed external Hamiltonian, it provides a method to find the proximity of the trial ground states to actual states of the theory. This technique is applied to the reconstruction examples in the continuum limit.     

Blackbody radiation in nonextensive Tsallis statistics: Exact solution

An exact analysis of n-dimensional blackbody radiation in the recently proposed nonextensive Tsallis statistics is given here. Thus, the main relationships of blackbody radiation are generalized in the Tsallis context. In particular, it is verified that the relation between pressure, volume, and internal energy is form invariant with respect to the nonextensive entropic index, q. The results and procedure presented here are expected to be useful in the discussion of nonextensive systems possessing large or infinite numbers of degrees of freedom.     

On potentials with fast growing point spectrum

Motivated by the fast growing spectra suggested by composite quark models, one discusses bounds on the growth rate of E_n = f(n) for potential models. Both local and non-local, monotonous and non-monotonous, potentials are considered. The emphasis is on qualitative estimates of the growth rate and on the search for interactions which are amenable to a simple physical interpretation.     

A new acousto-electro-optic improved resolution deflector for high frequency operation

The two main constrains on the characteristics of the acousto-optic deflector are the acoustic sound attenuation and velocity. These two parameters will determine the resolution and the radio frequency bandwidth.Due to a double degenerated phase matching condition on a specific acousto-optic deflector configuration, the possibility of an improvement on the resolution of the acousto optic deflector becomes evident. This degenerescence is the result of the action of a D.C. electric field by the electro-optic effect. This configuration presents several advantages upon the early related works based on optical activity of selected materials and enables a wideband interaction in such a way that the number of resolvable channels is kept high. This has implications on the acousto-optic spectrometers for wideband radio astronomy research.     

Pac studies of ZrMn2+x alloys and their hydrides

¹⁸¹Ta PAC and electron diffraction experiments on ZrMn₂ show that the presence of Hf in substitution for Zr at a concentration of 2 at. % can be responsible for distortions from the C14 structure of this intermetallic alloy. The PAC spectra recorded between RT and 50K for the hydride Zr_0.98 Hf_0.02 Mn₂H_3.2 display two successive modifications in the temperature regions 180–150K and 100–50K. In the present state of PAC data analysis, we are not able to claim that such modifications are related to the low-temperature magnetic properties of ZrMn₂ hydrides.     

Sur la structure du dibutylstannadioxa-2,6 cyclohexane

The structure of the dibutylstannadioxa cyclic derivatives from 1,3-propanediol has been the subject of many conflicting reports; some authors considering the species to be monomeric and others considering it to be dimeric. The preliminary results of an X-ray determination, show that in the solid state this compound is monomer with the molecules being bonded by strong coordination bonds.