Comment on Casimir force in compact non-commutative extra dimensions and radius stabilization

We call attention to a series of mistakes in a paper by S. Nam recently published in this journal (J. High Energy Phys. 10 (2000) 044).

Experimental and theoretical aspects of the stabilization of zirconia.

Using the Rietveld method, phases of ceria-doped zirconia, calcined at temperatures of 600 and 900 degrees C, were quantitatively analysed for different concentrations of ceria. The results show that the stabilization of zirconia depends on the dopant concentration and calcination temperature. Moreover, the theoretical calculation using the ab initio Hartree-Fock-Roothaan method indicates that the most stable phases for ceria-stabilized zirconia are cubic or tetragonal, in accordance with experimental results. (C) 1999 Kluwer Academic Publishers.

Effects of dispersion by Gd3+ upon europium diphenylphosphinate luminescence

A series of binary diphenylphosphinates with Eu3+ and Gd3+ were prepared. The compounds have the general formula Gd1-xEux(DPP)(3), where x ranges from 0 to 1. The spectroscopic measurements show interesting behavior. The intensity of the D-5(0) --> F-7(2) transitions decreases relative to D-5(0) --> F-7(1) With an increase in europium dispersion. Inside the temporal domain, the same decrease is observed with increasing delay after excitation. The lifetimes are also affected, which can be seen in the x = 1 compound, where the decay is a first-order process and lifetime values are 4.81 ms. In the binary compound, as an effect of dispersion, the lifetime of the D-5(0) level measured at the D-5(0) --> F-7(1) transition increases with europium dispersion, and the average along the series is 6.25 ms. The decay measured at the D-5(0) --> F-7(2) transitions reveals a second-order process with lifetimes ranging from 1.90 to 6.00 ms. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Enhanced Eu3+ Emission in Aqueous Phosphotungstate Colloidal Systems: Stabilization of Polyoxometalate Nanostructures

Luminescent Eu3+-containing polyphosphate tungstate aqueous colloidal systems were prgared and studied as a function of the relative polyphosphate tungstate content. In polyphosphate-rich solutions, Eu-H- ions occupy cagelike sites composed of phosphate groups from the metaphosphate chains. In these sites, an average number of 0.5 water molecule coordinates to an Eu3+ ion and the 500 emission quantum efficiency is 0.22. Tungstatc addition leads to important modifications in neighboring Eu3+ leading to coordination sites in the aqueous medium where metal ions are completely hidden from interactions with solvent molecules. Transmission electron microscopy results clearly show \V-rich nanoparticles with sizes between 5 and 10 nm for all tungstate relative concentrations. For high tungstatc relative contents (above 30 mol %), spectroscopic results suggest the presence of Eu34- in polyoxometalate (P0M)-like sites by comparison with the well-known decatungstoeuropate [EuW10O36](9-) structure. These new aqueous colloids display surprisingly high 5llo emission quantum efficiencies of ca 80% because of the strong ligand field provided by tungstate POM ligands and the complete absence of water molecules from the Eu3+ first coordination shell.

Joint control charts for monitoring location and dispersion

The T-2 and the generalized variance vertical bar S vertical bar charts are used for monitoring the mean vector and the covariance matrix of multivariate processes. In this article, we propose for bivariate processes the use of the T-2 and the VMAX charts. The points plotted on the VMAX chart correspond to the maximum of the sample variances of the two quality characteristics. The reason to consider the VMAX statistic instead of the generalized variance vertical bar S vertical bar is the user's familiarity with the computation of simple sample variances; we can't say the same with regard to the computation of the generalized variance vertical bar S vertical bar.

Optimal laser control of molecular photoassociation along with vibrational stabilization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stabilization of fluoroindate glasses by magnesium fluoride

This paper describes the stabilizing effect of MgF2 on the binary system InF3-BaF2. A complete investigation of the In-Ba-Mg system led to samples up to 5 mm in thickness. Further optimization of this system was achieved by incorporation of other fluorides, resulting in increased resistance to devitrification. Thermal and optical data are reported.

Dispersion relations and the spin polarizabilities of the nucleon

A forward dispersion calculation is implemented for the spin polarizabilities γ1, ⋯, γ4 of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at script O sign(ω3). In the absence of a direct experimental measurement of these quantities, a dispersion calculation serves the purpose of constraining the model building, and of comparing with recent calculations in heavy baryon chiral perturbation theory. © 1998 Elsevier Science B.V.

Bose-Einstein condensation for general dispersion relations

Bose-Einstein condensation in an ideal (i.e. interactionless) boson gas can be studied analytically, at university-level statistical and solid state physics, in any positive dimensionality (d > 0) for identical bosons with any positive-exponent (s > 0) energy-momentum (i.e. dispersion) relation. Explicit formulae with arbitrary dls are discussed for: the critical temperature (non-zero only if d/s > 1); the condensate fraction; the internal energy; and the constant-volume specific heat (found to possess a jump discontinuity only if d/s > 2) Classical results are recovered at sufficiently high temperatures. Applications to ordinary' Bose-Einstein condensation, as well as to photons, phonons, ferro-and antiferromagnetic magnons, and (very specially) to Cooper pairs in superconductivity, are mentioned.

Differential dispersion relations with an arbitrary number of subtractions: A recursive approach

Making use of a recursive approach, derivative dispersion relations are generalized for an arbitrary number of subtractions. The results for both cross even and odd amplitudes are theoretically consistent at sufficiently high energies and in the region of small momentum transfer. © 1999 Published by Elsevier Science B.V. All rights reserved.

The Real Plan: Stabilization and destabilization

The paper analyzes Brazil's Real Plan, an exchange-rate based stabilization program, implemented in 1994, which mixed a spectacular price stabilization with some serious macroeconomic destabilization. The paper focuses on two of these imbalances: the consumption boom and the financial destabilization; showing that the former represented nothing the reverse side of a collapsed investment boom, which, in turn, led to the financial (banking) crisis. We hold that these instabilities were produced by a policy arrangement in which monetary and fiscal policies alone had to compensate for a largely appreciated, almost fixed, exchange rate anchor. (C) 2000 Elsevier Science Ltd. All rights reserved.

Protected magnetic particles: Silica on yttrium iron garnet

The formation of silica on core yttrium iron garnet presents a variety of different applications as corrosion resistance and stabilization of magnetic properties. Well-defined magnetic particles were prepared by heterocoagulating silica on yttrium iron garnet to protect the core. Yttrium iron garnet was obtained using a homogeneous nucleation process by controlling the chemical routes from cation hydrolysis in acid medium. The heterocoagulation was induced by tetraethyl orthosilicate hydrolysis in appropriate yttrium iron garnet dispersion medium. The presence of silica on yttrium iron garnet was characterized by vibrating sample magnetometry, X-ray photoemission spectroscopy, transmission electron microscopy, small area electron diffraction and differential thermal analysis. © 2001 Elsevier Science B.V. All rights reserved.

PI Stabilization of a Class of Time Delay Systems

In this paper we use the Hermite-Biehler theorem to establish results for the design of proportional plus integral (PI) controllers for a class of time delay systems. We extend results of the polynomial case to quasipolynomials using the property of interlacing in high frequencies of the class of time delay systems considered. A signature for the quasipolynomials in this class is derived and used in the proposed approach which yields the complete set of the stabilizing PI controllers.

Stable two-dimensional dispersion-managed soliton

The existence of a dispersion-managed soliton in two-dimensional nonlinear Schrodinger equation with periodically varying dispersion has been explored. The averaged equations for the soliton width and chirp are obtained which successfully describe the long time evolution of the soliton. The slow dynamics of the soliton around the fixed points for the width and chirp are investigated and the corresponding frequencies are calculated. Analytical predictions are confirmed by direct partial differential equation (PDE) and ordinary differential equation (ODE) simulations. Application to a Bose-Einstein condensate in optical lattice is discussed. The existence of a dispersion-managed matter-wave soliton in such system is shown.

PID stabilization of a class of time delay systems

In this paper we use the Hermite-Biehler theorem to establish results for the design of proportional plus integral plus derivative (PID) controllers concerning a class of time delay systems. Using the property of interlacing at high frequencies of the class of systems considered and linear programming we obtain the set of all stabilizing PID controllers. © 2005 IEEE.