Hexagonal Tilings: Tutte Uniqueness

We develop the necessary machinery in order to prove that hexagonal tilings are uniquely determined by their Tutte polynomial, showing as an example how to apply this technique to the toroidal hexagonal tiling.Comment: 12 figure

Hexagonal Tilings and Locally C6 Graphs

We give a complete classification of hexagonal tilings and locally C6 graphs, by showing that each of them has a natural embedding in the torus or in the Klein bottle. We also show that locally grid graphs are minors of hexagonal tilings (and by duality of locally C6 graphs) by contraction of a perfect matching and deletion of the resulting parallel edges, in a form suitable for the study of their Tutte uniqueness.Comment: 14 figure

Reaction rate calculation with time-dependent invariant manifolds

The identification of trajectories that contribute to the reaction rate is the crucial dynamical ingredient in any classical chemical reactivity calculation. This problem often requires a full scale numerical simulation of the dynamics, in particular if the reactive system is exposed to the influence of a heat bath. As an efficient alternative, we propose here to compute invariant surfaces in the phase space of the reactive system that separate reactive from nonreactive trajectories. The location of these invariant manifolds depends both on time and on the realization of the driving force exerted by the bath. These manifolds allow the identification of reactive trajectories simply from their initial conditions, without the need of any further simulation. In this paper, we show how these invariant manifolds can be calculated, and used in a formally exact reaction rate calculation based on perturbation theory for any multidimensional potential coupled to a noisy environment

The quasi-cylindrical description of submerged laminar swirling jets

TThe quasi-cylindrical approximation is used to describe numerically the structure of a submerged swirling jet for subcritical values of the swirl ratio S<Sc . The emerging flow structure is affected by the swirling motion, which enhances the entrainment rate of the jet and induces an adverse pressure gradient that reduces its momentum flux. The effect is more pronounced as the swirl ratio S is increased, yielding for sufficiently large values of S a jet with an annular structure. The integration describes the smooth transition towards the far-field self-similar solution for all values of S smaller than a critical value S5Sc , at which the numerical integration fails to converge at a given downstream location. The comparisons with previous experimental results confirm the correspondence between the onset of vortex breakdown and the failure of the quasi-cylindrical approximation

Mortalidad atribuible al alcohol en Cataluña y sus provincias

ObjetivoEstimar la contribución del consumo de alcohol en la mortalidad de Cataluña en 1997, su impacto sobre la mortalidad prematura y evaluar si existen diferencias entre provincias.DiseñoEstudio ecológico, descriptivo.EmplazamientoCataluña.PacientesDefunciones de residentes en Cataluña en 1997 por una causa relacionada con el consumo excesivo de alcohol.Mediciones y resultados principalesLos datos de las causas de muerte en Cataluña en 1997 fueron facilitados por el Registre de Mortalitat de Catalunya y se usaron las fracciones poblacionales atribuibles al alcohol recomendadas por los Centers for Disease Control de Estados Unidos en 1987. Se estimó la mortalidad atribuible al alcohol (MAA) y los años potenciales de vida perdidos (APVP) para el conjunto de Cataluña y desagregada por provincias.Un 4,8% de la mortalidad de Cataluña en 1997 estuvo relacionada con el consumo excesivo de alcohol. La mortalidad fue más elevada en varones (6,0%) que en mujeres (3,5%). Por grupos diagnósticos, las neoplasias malignas (29,9%) contribuyeron con un mayor número de MAA, mientras que los accidentes no intencionales presentaron la mayor mortalidad prematura (50,9%). Por causa específica, el mayor número de APVP correspondió a los accidentes de vehículos a motor. Por provincias, se observó mayor MAA por accidentes no intencionales en todas las provincias respecto a Barcelona y menor riesgo de muerte por enfermedades digestivas.ConclusiónEste estudio pone de manifiesto la importante implicación del alcohol en la mortalidad, así como su contribución en la mortalidad prematura y la existencia de importantes diferencias según la provincia de residencia, especialmente para accidentes no intencionales.ObjectivesTo calculate the contribution of alcohol consumption to mortality in Catalonia in 1997, and its impact on premature mortality. To evaluate whether inter-provincial differences exist.DesignDescriptive ecological study.SettingCatalonia.PatientsDeaths of residents of Catalonia in 1997 for a cause related to excess alcohol consumption.Measurements and main resultsThe data on the causes of death in Catalonia in 1997 were provided by the Catalonia Death Register. The population fractions attributable to alcohol used were those recommended by the United States Centers for Disease Control in 1987. Mortality attributable to alcohol and the potential years of life lost were calculated for Catalonia as a whole and province by province. 4.8% of mortality in Catalonia in 1997 was related to excessive alcohol consumption. Mortality was higher in men (6.0%) than in women (3.5%). By diagnostic groups, malignant neoplasms (29.9%) contributed to the greatest number of deaths attributable to alcohol, whereas non-intentional accidents was the greatest cause of premature death (50.9%). As a specific cause, the greatest number of potential years of life lost was due to motor vehicle accidents. The highest mortality rate due to alcohol in non-intentional accidents and the lowest risk of death from digestive diseases were in all the provinces rather than in Barcelona.ConclusionThis study highlighted the importance of alcohol in the mortality figures, its contribution to premature death and the existence of major differences depending on the province of residence, especially in non-intentional accidents