Computing vs. Genetics

This chapter first presents the interrelations between computing and genetics, which both are based on information and, particularly, self-reproducing artificial systems. It goes on to examine genetic code from a computational viewpoint. This raises a number of important questions about genetic code. These questions are stated in the form of an as yet unpublished working hypothesis. This hypothesis suggests that many genetic alterations are caused by the last base of certain codons. If this conclusive hypothesis were to be confirmed through experiementation if would be a significant advance for treating many genetic diseases

A cooperative conjugate gradient method for linear systems permitting multithread implementation of low complexity

This paper proposes a generalization of the conjugate gradient (CG) method used to solve the equation $Ax=b$ for a symmetric positive definite matrix $A$ of large size $n$. The generalization consists of permitting the scalar control parameters (= stepsizes in gradient and conjugate gradient directions) to be replaced by matrices, so that multiple descent and conjugate directions are updated simultaneously. Implementation involves the use of multiple agents or threads and is referred to as cooperative CG (cCG), in which the cooperation between agents resides in the fact that the calculation of each entry of the control parameter matrix now involves information that comes from the other agents. For a sufficiently large dimension $n$, the use of an optimal number of cores gives the result that the multithread implementation has worst case complexity $O(n^{2+1/3})$ in exact arithmetic. Numerical experiments, that illustrate the interest of theoretical results, are carried out on a multicore computer.Comment: Expanded version of manuscript submitted to the IEEE-CDC 2012 (Conference on Decision and Control

X-rays from the colliding wind binary WR 146

The X-ray emission from the massive binary WR 146R is analysed in the framework of the colliding stellar wind (CSW) picture. The theoretical CSW model spectra match well the shape of the observed X-ray spectrum of WR 146R but they overestimate considerably the observed X-ray flux (emission measure). This is valid both in the case of complete temperature equalization and in the case of partial electron heating at the shock fronts (different electron and ion temperatures), but, there are indications for a better correspondence between model predictions and observations for the latter. To reconcile the model predictions and observations, the mass-loss rate of WR 146 must be reduced by a factor of 8 - 10 compared to the currently accepted value for this object (the latter already takes clumping into account). No excess X-ray absorption is derived from the CSW modelling.Comment: Accepted for publication in MNRAS; 9 pages, 4 figires, 1 tabl

Solving SAT in linear time with a neural-like membrane system

We present in this paper a neural-like membrane system solving the SAT problem in linear time. These neural Psystems are nets of cells working with multisets. Each cell has a finite state memory, processes multisets of symbol-impulses, and can send impulses (?excitations?) to the neighboring cells. The maximal mode of rules application and the replicative mode of communication between cells are at the core of the eficiency of these systems

In memoriam. La obra de Claude Lévi–Strauss (1908–2009). Unidad humana y diferencia cultural

Uno de los temas fundamentales de la obra del antropólogo francés Claude Lévi–Strauss, recientemente fallecido, es el de la relación entre unidad humana y diferencia cultural. De diversas maneras, tanto en sus trabajos teóricos como en sus intervenciones públicas, Lévi– Strauss adoptó una particular forma de relativismo cultural. En este artículo se repasa lo que esta posición debe a los presupuestos básicos del estructuralismo; se refl exiona asimismo sobre las diversas nociones de Lévi–Strauss respecto de la unidad humana; y se introduce una crítica del relativismo estructuralista y una defensa de un universalismo de lo social.One of the main subjects in the work of Claude Lévi–Strauss, the recently deceased French anthropologist, is the relationship between human unity and cultural diversity. Both in his theoretical works and in his public presentations, Lévi–Strauss adopted a particular form of cultural relativism. In this article, an overview of what this position owes to the basic assumptions of structuralism is provided. Also, a thinking on Lévi–Strauss different notions regarding human unity is given, together with a criticism of the structuralist relativism and a defence of the universalism of the social field