Analytic Non-integrability in String Theory

Using analytic techniques developed for Hamiltonian dynamical systems we show that a certain classical string configurations in AdS_5 x X_5 with X_5 in a large class of Einstein spaces, is non-integrable. This answers the question of integrability of string on such backgrounds in the negative. We consider a string localized in the center of AdS_5 that winds around two circles in the manifold X_5.Comment: 14 page

Nonautonomous Hamiltonian Systems and Morales-Ramis Theory I. The Case x¨=f(x,t)\ddot{x}=f(x,t)

In this paper we present an approach towards the comprehensive analysis of the non-integrability of differential equations in the form $\ddot x=f(x,t)$ which is analogous to Hamiltonian systems with 1+1/2 degree of freedom. In particular, we analyze the non-integrability of some important families of differential equations such as Painlev\'e II, Sitnikov and Hill-Schr\"odinger equation. We emphasize in Painlev\'e II, showing its non-integrability through three different Hamiltonian systems, and also in Sitnikov in which two different version including numerical results are shown. The main tool to study the non-integrability of these kind of Hamiltonian systems is Morales-Ramis theory. This paper is a very slight improvement of the talk with the almost-same title delivered by the author in SIAM Conference on Applications of Dynamical Systems 2007.Comment: 15 pages without figures (19 pages and 6 figures in the published version

Sustainable business models: integrating employees, customers and technology

This Special Issue of the Journal of Business & Industrial Marketing has the same title as the 23rd International Conference CBIM 2018 (June 18-20, 2018, Madrid, Spain) “Sustainable Business Models: Integrating Employees, Customers and Technology”. In this edition of International Conference, following a competitive blind review process, papers from 126 authors and 25 countries were ultimately accepted. The best papers of the Conference were invited to submit to this Special Issue and we were also open to direct submissions from other authors. We present here the 17 accepted papers for publication in this Special Issue

Synchrotron strain scanning for residual stress measurement in cold-drawn steel rods

Cold-drawn steel rods and wires retain significant residual stresses as a consequence of the manufacturing process. These residual stresses are known to be detrimental for the mechanical properties of the wires and their durability in aggressive environments. Steel makers are aware of the problem and have developed post-drawing processes to try and reduce the residual stresses on the wires. The present authors have studied this problem for a number of years and have performed a detailed characterization of the residual stress state inside cold-drawn rods, including both experimental and numerical techniques. High-energy synchrotron sources have been particularly useful for this research. The results have shown how residual stresses evolve as a consequence of cold-drawing and how they change with subsequent post-drawing treatments. The authors have been able to measure for the first time a complete residual strain profile along the diameter in both phases (ferrite and cementite) of a cold-drawn steel rod

Steady self-diffusion in classical gases

A steady self-diffusion process in a gas of hard spheres at equilibrium is analyzed. The system exhibits a constant gradient of labeled particles. Neither the concentration of these particles nor its gradient are assumed to be small. It is shown that the Boltzmann-Enskog kinetic equation has an exact solution describing the state. The hydrodynamic transport equation for the density of labeled particles is derived, with an explicit expression for the involved self-diffusion transport coefficient. Also an approximated expression for the one-particle distribution function is obtained. The system does not exhibit any kind of rheological effects. The theoretical predictions are compared with numerical simulations using the direct simulation Monte Carlo method and a quite good agreement is found