Interdisciplinary Monte Carlo Simulations

Biological, linguistic, sociological and economical applications of statistical physics are reviewed here. They have been made on a variety of computers over a dozen years, not only at the NIC computers. A longer description can be found in our new book, an emphasis on teaching in Eur.J.Phys. 26, S 79 and AIP Conf. Proc. 779, 49, 56, 69 and 75.Comment: 11 pages including many Figs.; for 3rd NIC Symposium, Julich, 3/0

Hot electroweak matter near to the endpoint of the phase transition

The electroweak phase transition is investigated near to its endpoint in the framework of an effective three-dimensional model. We measure the very weak interface tension with the tunneling correlation length method. First results for the mass spectrum and the corresponding wave functions in the symmetric phase are presented.Comment: 3 pages, 5 figures, uses espcrc2.sty, contribution to LATTICE9

Introduction

Species categories are not simply an invention of the human mind. Plants, animals, fungi, and viruses engage in species making by mingling and separating.1 Yet, at the same time, the boundaries that define or differentiate species are not simply natural ; they are actively made, maintained, politically charged, and fashioned to serve some needs more than others, inviting new essentialisms even as they alert us to important differences. Like other rubrics for organizing social worlds—race, ethnicity, gender, age, ability—the concept of species and the alternative classifications it invites are complicated and controversial. Whether wild or domestic, pet or pest, such categories are subject to temporally fluctuating human motives, shifting values, and cultural diversities

Introduction

Species categories are not simply an invention of the human mind. Plants, animals, fungi, and viruses engage in species making by mingling and separating.1 Yet, at the same time, the boundaries that define or differentiate species are not simply natural ; they are actively made, maintained, politically charged, and fashioned to serve some needs more than others, inviting new essentialisms even as they alert us to important differences. Like other rubrics for organizing social worlds—race, ethnicity, gender, age, ability—the concept of species and the alternative classifications it invites are complicated and controversial. Whether wild or domestic, pet or pest, such categories are subject to temporally fluctuating human motives, shifting values, and cultural diversities

Interaction effects in the spectrum of the three-dimensional Ising model

The two-point correlation functions of statistical models show in general both poles and cuts in momentum space. The former correspond to the spectrum of massive excitations of the model, while the latter originate from interaction effects, namely creation and annihilation of virtual pairs of excitations. We discuss the effect of such interactions on the long distance behavior of correlation functions in configuration space, focusing on certain time-slice operators which are commonly used to extract the spectrum. For the 3D Ising model in the scaling region of the broken-symmetry phase, a one-loop calculation shows that the interaction effects on time-slice correlations is non negligible for distances up to a few times the correlation length, and should therefore be taken into account when analysing Monte Carlo data.Comment: 10 pages, LaTeX file + 1 ps figure, uses axodraw.st

Structure of penetrable-rod fluids: Exact properties and comparison between Monte Carlo simulations and two analytic theories

Bounded potentials are good models to represent the effective two-body interaction in some colloidal systems, such as dilute solutions of polymer chains in good solvents. The simplest bounded potential is that of penetrable spheres, which takes a positive finite value if the two spheres are overlapped, being 0 otherwise. Even in the one-dimensional case, the penetrable-rod model is far from trivial, since interactions are not restricted to nearest neighbors and so its exact solution is not known. In this paper we first derive the exact correlation functions of penetrable-rod fluids to second order in density at any temperature, as well as in the high-temperature and zero-temperature limits at any density. Next, two simple analytic theories are constructed: a high-temperature approximation based on the exact asymptotic behavior in the limit $T\to\infty$ and a low-temperature approximation inspired by the exact result in the opposite limit $T\to 0$. Finally, we perform Monte Carlo simulations for a wide range of temperatures and densities to assess the validity of both theories. It is found that they complement each other quite well, exhibiting a good agreement with the simulation data within their respective domains of applicability and becoming practically equivalent on the borderline of those domains. A perspective on the extension of both approaches to the more realistic three-dimensional case is provided.Comment: 19 pages, 11 figures, 4 tables: v2: minor changes; published final versio

Finite Size Effects in Fluid Interfaces

It is shown that finite size effects in the free energy of a rough interface of the 3D Ising and three--state Potts models are well described by the capillary wave model at {\em two--loop} order. The agreement between theoretical predictions and Monte Carlo simulations strongly supports the idea of the universality of this description of order--order interfaces in 3D statistical systems above the roughening temperature.Comment: 3 pages, uuencoded .ps file, figures included. (Proceeding of Lattice '93

Agenda 21 local como herramienta de desarollo sostenible : La situación en Suiza

1999an Suitzak bere konpromisoa bete zuen, garapen iraunkorra Konstituzioan barneratu baitzuen. Herrialde hau Tokiko Agenda 21 delakoaren moduko prozesu zehatzak sustatzeko hainbat estrategia ari da probatzen. 2005eko uztailean, Suitzako udalerrien % 4 baino ez zegoen prozesu honetan sartuta; hau da, biztanleriaren % 29. Suitzako tokiko agintaritzek, sistema federala dela eta, autonomia handia izan dute aspalditik; gainera, biztanleek demokrazia zuzeneko sistema suitzarraren bidez, Europako beste herrialde batzuetan baino zuzenago parte har dezakete erabaki politikoak hartzerakoan. Epe luzera, Garapen Iraunkorreko Estrategia Nazionalaren helburua garapen iraunkorra agintari publikoen jarduera eta politika guztietan barneratzea da.In 1999, Switzerland made good its pledge by writing sustainable development into its Constitution. Different strategies and programs are going on to promote Agenda 21-like processes. In July 2005, just 4% of municipalities were involved in the process, though this does represent 29% of the population. In Switzerland, under the country¿s federal system, local authorities have for a long time enjoyed considerable autonomy and, under the Swiss system of direct democracy, citizens are able to participate more fully in all political decision-making than in other countries. In the longer term, the aim of the National Sustainable development Strategy is to include sustainable development in all the policies and activities of public authorities.En 1999, Suiza cumplió con su compromiso al incluir el desarrollo sostenible en la Constitución. Este país está ensayando diferentes estrategias para fomentar determinados procesos del estilo de la Agenda 21 Local. En julio de 2005, tan sólo un 4% de los municipios suizos se habían involucrado en este proceso, si bien representan un 29% de la población. Las autoridades locales suizas, bajo un sistema federal, han disfrutado durante mucho tiempo de una autonomía considerable. Y los ciudadanos, mediante el sistema suizo de democracia directa, pueden participar de una manera más activa que en otros países europeos en la toma de decisiones políticas. A largo plazo, el objetivo de la Estrategia Nacional de Desarrollo Sostenible es incluir el desarrollo sostenible en todas las actividades y políticas de las autoridades pública