The Tausk Controversy on the Foundations of Quantum Mechanics: Physics, Philosophy, and Politics

In 1966 the Brazilian physicist Klaus Tausk (b. 1927) circulated a preprint from the International Centre for Theoretical Physics in Trieste, Italy, criticizing Adriana Daneri,Angelo Loinger,and Giovanni Maria Prosperi’s theory of 1962 on the measurement problem in quantum mechanics. A heated controversy ensued between two opposing camps within the orthodox interpretation of quantum theory, represented by Léon Rosenfeld and Eugene P.Wigner. The controversy went well beyond the strictly scientific issues, however, reflecting philosophical and political commitments within the context of the Cold War, the relationship between science in developed and Third World countries, the importance of social skills, and personal idiosyncrasies.     

Confinement from new global defect structures

We investigate confinement from new global defect structures in three spatial dimensions. The global defects arise in models described by a single real scalar field, governed by special scalar potentials. They appear as electrically, magnetically or dyonically charged structures. We show that they induce confinement, when they are solutions of effective QCD-like field theories in which the vacua are regarded as color dielectric media with an antiscreening property. As expected, in three spatial dimensions the monopole-like global defects generate the Coulomb potential as part of several confining potentials.Received: 25 August 2004, Published online: 16 March 2005PACS: 11.27. + d, 12.39.-x     

Metal-insulator transition in two- and three-dimensional logarithmic plasmas

We consider the scaling of the mean square dipole moment in a plasma with logarithmic interactions in a two- and three-dimensional systems. In both cases, we establish the existence of a low-temperature regime where the mean square dipole moment does not scale with system size and a high-temperature regime where it does scale with system size. Thus, there is a nonanalytic change in the polarizability of the system as a function of temperature and hence a metal-insulator transition in both cases. The relevance of this transition in three dimensions to quantum phase transitions in (2+1)-dimensional systems is briefly discussed.     

Influence of velocity in nanoscale friction processes

Force-microscopy images of boric acid crystals were obtained experimentally and simulated with the use of a two-dimensional mechanical model. An analysis of the stick and slip movement of the microscope tip shows that the energy-dissipation mechanism is strongly influenced by the non-linear dynamics of the sliding system. The contributions of stick and viscous forces on the energy dissipation (or friction forces) are studied as a function of the relative scanning velocity. At low relative velocities, the stick forces are shown to be responsible for the energy dissipation. This energy is velocity-dependent, due to the coupling between the two degrees of freedom of the sliding system. As the scanning velocity increases the stick forces are damped; the viscous force is then predominant in the energy-dissipation process. Received: 30 October 2001 / Accepted: 17 May 2002 / Published online: 22 November 2002 RID="*" ID="*"Corresponding author. Fax: +55-21/2295-9397, E-mail: prioli@vdg.fis.puc-rio.br     

An attempt to correlate fat and protein content of biological samples with residual carbon after microwave-assisted digestion

The residual carbon content of a variety of bovine-derived samples and forage was determined by inductively coupled plasma optical emission spectrometry with radial view configuration (ICP-OES) after microwave-assisted digestion under high pressure in a closed vessel. The original carbon concentration in the samples was determined by elemental analysis. The highest amount of original carbon content (64%) was found in viscera. After digestion, up to 75% of it was destroyed. Viscera presented the highest ether extract and blood exhibited a high crude protein content of up to 99%. The efficiency in destroying the organic matter in biological materials seemed to be related to their fat content and showed no significant difficulty for protein-rich samples. The correlation coefficient between the fat content of the samples and the residual carbon after acid decomposition was 0.9173 indicating a fair fit. However, no correlation was observed between % RC and the protein content.     

On the paper “Symmetry analysis of wave equation on sphere” by H. Azad and M.T. Mustafa

Using the scalar curvature of the product manifold S²×R and the complete group classification of nonlinear Poisson equation on (pseudo) Riemannian manifolds, we extend the previous results on symmetry analysis of homogeneous wave equation obtained by H. Azad and M.T. Mustafa [H. Azad, M.T. Mustafa, Symmetry analysis of wave equation on sphere, J. Math. Anal. Appl. 333 (2007) 1180-1188] to nonlinear Klein-Gordon equations on the two-dimensional sphere.     

Resolution of computational aeroacoustics problems on unstructured grids with a higher-order finite volume scheme

Computational fluid dynamics (CFD) has become increasingly used in the industry for the simulation of flows. Nevertheless, the complex configurations of real engineering problems make the application of very accurate methods that only work on structured grids difficult. From this point of view, the development of higher-order methods for unstructured grids is desirable. The finite volume method can be used with unstructured grids, but unfortunately it is difficult to achieve an order of accuracy higher than two, and the common approach is a simple extension of the one-dimensional case. The increase of the order of accuracy in finite volume methods on general unstructured grids has been limited due to the difficulty in the evaluation of field derivatives. This problem is overcome with the application of the Moving Least Squares (MLS) technique on a finite volume framework. In this work we present the application of this method (FV-MLS) to the solution of aeroacoustic problems.     

Electromagnetic properties of theZ boson

Direct (nonresonant) 3-body decays of charmed mesons are calculated in chiral perturbation theory. The magnitudes of the 20 and 84 representations of the effective chiralSU(4)×SU(4) Lagrangian are determined from the measured 2-bodyD→Kπ rate. For decay modes which do not contain nonspectator contributions, the agreement of theoretical predictions with the data is satisfactory. Nevertheless, the large discrepancy between theory and experiment for decays which can proceed through theW-exchange orW-annihilation might imply the importance of nonperturbative corrections to the nonspectator diagram and the existence of final-state interactions.     

catena-Poly­[[di­aqua(1,10-phen­anthroline-N,N′)­manganese(II)]-μ-(thiosulfato-O:S)] and bis(2,2′-bipyridyl-N,N′)(tetra­thionato-O,O′)manganese(II)

The structures of [Mn(S₂O₃)₂(C₁₂H₈N₂)(H₂O)₂] and [Mn(S₄O₆)(C₁₀H₈N₂)₂] are presented. The former consists of pairs of polymeric chains formed by manganese polyhedra bridged by bidentate thio­sulfate anions, which are in turn related to each other by a pseudo-twofold screw axis. The latter has crystallographic twofold symmetry and consists of monomers in which manganese displays its typical octahedral coordination provided by the bidentate bites of two bi­pyridine bases and a tetra­thionate anion, which is, to our knowledge, the first chelating tetra­thionate to be reported in the literature.