Non-commutative geometry and irreversibility

A kinetics built upon $q$-calculus, the calculus of discrete dilatations, is shown to describe diffusion on a hierarchical lattice. The only observable on this ultrametric space is the "quasi-position" whose eigenvalues are the levels of the hierarchy, corresponding to the volume ofphase space available to the system at any given time. Motion along the lattice of quasi-positions is irreversible.Comment: 15 pages, 2 figures, Revtex formatte

Statistics of a hydrophobic chain near a hydrophobic boundary

We study the behaviour of a hydrophobic chain near a hydrophobic boundary in two dimensions, using the decorated lattice model of Berkema and Widom [G.T. Barkema and B. Widom, J. Chem. Phys. 113, 2349 (2000)] to obtain effective, temperature dependent intrachain and chain-boundary interactions. We use these interactions to construct two model hamiltonians which can be solved exactly. Our results compare favorably with preliminary Monte Carlo computations, using the same effective interactions. At relatively low temperatures and at high temperatures, we find that the chain is randomly configured in the ambient water, and detached from the wall, whereas at intermediate temperatures it adsorbs onto the wall in a stretched or partially folded state, again depending upon the temperature, and the energy of solvation.Comment: 6 pages text, 11 figure

Random model for RNA interference yields scale free network

We introduce a random bit-string model of post-transcriptional genetic regulation based on sequence matching. The model spontaneously yields a scale free network with power law scaling with $\gamma=-1$ and also exhibits log-periodic behaviour. The in-degree distribution is much narrower, and exhibits a pronounced peak followed by a Gaussian distribution. The network is of the smallest world type, with the average minimum path length independent of the size of the network, as long as the network consists of one giant cluster. The percolation threshold depends on the system size.Comment: 9 pages, 13 figures, submitted to Midterm Conference COSIN on ``Growing Networks and Graphs in Statistical Physics, Finance, Biology and Social Systems'', Rome, 1-5 September 200

Dissipative Dynamics and the Statistics of Energy States of a Hookean Model for Protein Folding

A generic model of a random polypeptide chain, with discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues, reproduces the energy probability distribution of real proteins over a very large range of energies. We show that this system with harmonic interactions, under dissipative dynamics driven by random noise, leads to a distribution of energy states obeying a modified one-dimensional Ornstein-Uhlenbeck process and giving rise to the so called Wigner distribution. A tunably fine- or coarse-grained sampling of the energy landscape yields a family of distributions for the energies and energy spacings.Comment: RevTeX, 24 pages, including 8 figure

GUERRA, TERRORISMO AMBIENTAL Y LA NECESIDAD DE SOLIDARIDAD CON IRAK

El Tribunal Mundial sobre Irak, que llevó a cabo sus últimas audiencias en Estambul en junio de 2005, halló culpables a los Estados Unidos y a la Coalición de la buena voluntad , de crímenes de guerra y crímenes contra la humanidad, tal como está establecido por leyes comunes internacionales, los Principios de Nuremberg y las Convenciones de Ginebra. Científicos alrededor del mundo tienen el deber de ser conscientes de la devastación causada a Irak en términos humanos, culturales y ambientales, así como de la violencia dirigida contra los científicos iraquíes

Guerra, terrorismo ambiental y la necesidad de solidaridad con Irak

El Tribunal Mundial sobre Irak, que llevó a cabo sus últimas audiencias en Estambul en junio de 2005, halló culpables a los Estados Unidos y a la “Coalición de la buena voluntad”, de crímenes de guerra y crímenes contra la humanidad, tal como está establecido por leyes comunes internacionales, los Principios de Nuremberg y las Convenciones de Ginebra. Científicos alrededor del mundo tienen el deber de ser conscientes de la devastación causada a Irak en términos humanos, culturales y ambientales, así como de la violencia dirigida contra los científicos iraquíes