The minimal volume orientable hyperbolic 2-cusped 3-manifolds

We prove that the Whitehead link complement and the (-2, 3, 8) pretzel link complement are the minimal volume orientable hyperbolic 3-manifolds with two cusps, with volume 3.66... = 4 x Catalan's constant. We use topological arguments to establish the existence of an essential surface which provides a lower bound on volume and strong constraints on the manifolds that realize that lower bound.Comment: 10 pages, 5 figures, incorporated referees comments, includes hyperref link

Glassy behavior of the site frustrated percolation model

The dynamical properties of the site frustrated percolation model are investigated and compared with those of glass forming liquids. When the density of the particles on the lattice becomes high enough, the dynamics of the model becomes very slow, due to geometrical constraints, and rearrangement on large scales is needed to allow relaxation. The autocorrelation functions, the specific volume for different cooling rates, and the mean square displacement are evaluated, and are found to exhibit glassy behavior.Comment: 8 pages, RevTeX, 11 fig

Evaluacion del uso de restricciones de adyacencia en una planificacion de aprovechamiento forestal

64 p.Se realizó una evaluación de la planificación volumétrica de una empresa forestal al considerar variables restrictivas de adyacencia en su planificación táctica. Se formularon modelos de programación por objetivos, minimizando desviaciones asociadas a objetivos volumétricos por períodos y horizonte táctico para cada predio. Los resultados muestran, al incluir restricciones de adyacencia en la planificación táctica de la empresa, una leve diferencia de un 8% menos de volumen a cosechar. SUMMARY An evaluation of the effect on volume planning by a forest enterprise when adjacency constraints are considered in its tactical planning was developed. Goal programming models were formulated, minimizing deviations associated with volumetric goals by periods and tactical horizon for each management area. The results show, when adjacency constraints are included in tactical planning, a moderated difference of 8% less of projected harvest volume