Short range order effects and the Falicov-Kimball model

The model of Falicov and Kimball is investigated incorporating short range order effects. This modifies both the electronic density of states and the configurational entropy, relative to the fully disordered case. The way this affects the conditions under which phase transitions occur is evaluated and discussed.     

Further neo-clerodane diterpenes from Linaria saxatilis (L.) chaz

Ele ven $\text{neo}$-clerodane diterpenoids were isolated from the aerial parts of $\text{Linaria saxatilis}$. Their structures were determined by spectroscopic and chemical methods including the transformation of one of them into the known solidagolactone.     

Singular cosphere bundle reduction

This paper studies singular contact reduction for cosphere bundles at the zero value of the momentum map. A stratification of the singular quotient, finer than the contact one and better adapted to the bundle structure of the problem, is obtained. The strata of this new stratification are a collection of cosphere bundles and coisotropic or Legendrian submanifolds of their corresponding contact components.

     

Asymptotically sharp uniform estimates in a scalar spectral stiff problemEstimations asymptotiques uniformes pour le spectre d'un problème scalaire raide

Estimates of convergence rates for rescaled eigenvalues of the stiff Neumann problem for the Laplacian are obtained. The bounds are expressed in terms of the stiffness ratio and properties of the limit spectrum both for low and middle frequency ranges. To cite this article: M. Lobo et al., C. R. Mecanique 331 (2003).     

On the existence of asymptotically stable solutions of certain integral equations

In this paper two existence results of asymptotically stable solutions of certain integral equations are presented.     

POTENTIOMETRIC and LASER FLASH PHOTOLYSIS STUDIES OF THE pH DEPENDENCE OF HYDROGEN PEROXIDE PRODUCTION BY THE SEMICARBAZIDE/LUMIFLAVIN/OXYGEN PHOTOSYSTEM

The effect of pH on hydrogen peroxide photoproduction by the semicarbazide/lumiflavin/ oxygen system has been investigated by using the potentiometric and laser flash photolysis techniques. Kinetic analysis of (a) primary and secondary reactions involved in the photoreduction of lumiflavin and (b) lumiflavin reoxidation by oxygen have been carried out at varying pH values, drastic differences being observed in the pH dependence of both types of reactions. The reaction mechanism appears to proceed by semicarbazide-quenching (reductive type) of the light-excited lumiflavin in its triplet state followed, depending on pH, either by reoxidation of the so formed flavosemiquinone by molecular oxygen or by flavosemiquinone disproportionation into oxidized and fully reduced lumiflavin.     

Structure of Lorentzian tori with a killing vector field

All Lorentzian tori with a non-discrete group of isometries are characterized and explicitly obtained. They can lie into three cases: (a) flat, (b) conformally flat but non-flat, and (c) geodesically incomplete. A detailed study of many of their properties (including results on the logical dependence of the three kinds of causal completeness, on geodesic connectedness and on prescribed curvature) is carried out. The incomplete case is specially analyzed, and several known examples and results in the literature are generalized from a unified point of view.