Weak compactness of wave maps and harmonic maps

We show that a weak limit of a sequence of wave maps in (1 + 2) dimensions with uniformly bounded energy is again a wave map. Essential ingredients in the proof are Hodge structures related to harmonic maps, ¹ estimates for Jacobians, ¹-BMO duality, a “monotonicity” formula in the hyperbolic context and the concentration compactness method. Application of similar ideas in the elliptic context yields a drastically shortened proof of recent results by Bethuel on Palais-Smale sequences for the harmonic map functional on two dimensional domains and on limits of almost H-surfaces.     

Monodromy,center–focus and integrability problems for quasi-homogeneous polynomial systems

This paper deals with planar quasi-homogeneous polynomial vector fields, and addresses three major questions: the monodromy, the center–focus and the integrability problems. We characterize the monodromic planar quasi-homogeneous polynomial vector fields, and we give a condition to distinguish between a center and a focus in this case. Also, we provide conditions which characterize the integrability of quasi-homogeneous polynomial systems under non-resonance conditions. The results obtained allow us to analyse two monodromic planar systems with degenerate linear part: one of them with nilpotent linearization, and another one with null linear part.     

The structure of relations in personnel management

This paper addresses the problem of defining and analyzing relations between finite sets which are involved in personnel management.Personnel management criteria are imprecise due to the complex nature of the requirements and the difficulties to deal with personnel characteristics. Fuzzy set theory seems to be an efficient tool for considering these imprecisions. According to this idea the relations involved in personnel management can be seen as fuzzy relations.R.H. Atkin has formulated the abstract simplicial complex, achieving a structure which permits a deep knowledge of non fuzzy relations. In a sense this structure can be interpreted as a geometrical multidimensional one. Our purpose is to set up a multidimensional structure associated with the fuzzy relations which appear in personnel management.By means of an analysis of the above structure it is possible to study problems concerning the recruitment selection and promotion of personnel.     

Excess thermodynamics properties of propyl propanoate+hexane+cyclohexane at 298.15 K

Summary In this paper we present excess molar volumes and excess molar enthalpies of binary and ternary mixtures containing propyl propanoate, hexane and cyclohexane as components at 298.15 K. Excess molar volumes were calculated from the density of the pure liquids and mixtures. The density was measured using an Anton Paar DMA 60/602 vibrating-tube densimeter. Excess molar enthalpies were obtained using a Calvet microcalorimeter     

Structure-property relations in crystalline L-leucine obtained from calorimetry, X-rays, neutron and Raman scattering

We have studied the amino acid L-leucine (LEU) using inelastic neutron scattering, X-rays and neutron diffraction, calorimetry and Raman scattering as a function of temperature, focusing on the relationship between the local dynamics of the NH(3), CH(3), CH(2) and CO(2) moieties and the molecular structure of LEU. Calorimetric and diffraction data evidenced two novel phase transitions at about 150 K (T(1)) and 275 K (T(2)). The dynamical susceptibility function, obtained from the inelastic neutron scattering results, shows a re-distribution of the intensity of the vibrational bands that can be directly correlated with the phase transitions observed at T(1) and T(2), as well as with the already reported phase transition at T(3) = 353 K. Through the analysis of the Raman modes, the new structural arrangement observed below T(1) was related to conformational modifications of the CH and CH(3) groups, while the behavior of the N-H stretching vibration, ν(NH(3)), gave insight into the intermolecular N-H…O interactions. The observation of changes in the translational symmetry in the crystalline lattice, as well as anharmonic dynamics, allows for localized motions in LEU.     

Role of the adsorption phenomenon on the ionic equilibrium distribution and on the transient effects in electrolytic cells

We analyze the influence of the adsorption of ions at the interfaces on the transient phenomena occurring in an electrolytic cell submitted to a steplike external voltage. In the limit of small amplitude of the applied voltage, where the equation of the problem can be linearized, we obtain an analytical solution for the bulk and surface densities of ions and for the electrical potential. We also obtain, in this limit, the relaxation time for the transient phenomena.