Sound focusing by gradient index sonic lenses

Gradient index sonic lenses based on two-dimensional sonic crystals are here designed, fabricated and characterized. The index-gradient is achieved in these type of flat lenses by a gradual modification of the sonic crystal filling fraction along the direction perpendicular to the lens axis. The focusing performance is well described by an analytical model based on ray theory as well as by numerical simulations based on the multiple-scattering theory.Comment: 4 pages, 4 figure

Laboratory measurements of the wave-induced motion of plastic particles: influence of wave period, plastic size and plastic density

The transport of plastic particles from inland sources to the oceans garbage patches occurs trough coastal regions where the transport processes depend highly on wave-induced motions. In this study, experimental measurements of the plastic particles wave-induced Lagrangian drift in intermediate water depth are presented investigating the influence of the wave conditions, particle size and density on the motion of relatively large plastic particles. A large influence of the particle density is observed causing particles to float or sink for relative densities lower and larger than water respectively. The measured net drift of the floating particles correlates well with theoretical solutions for particle Stokes drift, where the net drift is proportional to the square of the wave steepness. Floating particles remain at the free water surface because of buoyancy and no evidence of any other influence of particle inertia on the net drift is observed. Nonfloating particles move close to the bed with lower velocity magnitudes than the floating particles’ motion at the free surface. The drift of nonfloating particles reduces with decreasing wave number, and therefore wave steepness.Peer ReviewedPostprint (published version

Laringitis granulomatosa en un perro

Perra mestiza de 13 años de edad con un historial de disnea aguda, debida a una obstrucción laríngea causada por una laringitis granulomatosa. Enfermedad de causa desconocida, posiblemente similar a la sarcoidosis humana

Estudio del inicio y la finalización de la dentición permanente en un grupo de escolares de una población catalana

Este estudio pretende observar la erupción de la dentición permanente en niños y niñas residentes en una población de la provincia de Barcelona. La muestra se estudió en cuanto al sexo, la edad y los primeros y segundos molares erupcionados, encontrando que la primera pieza en aparecer es el primer molar a partir de los 5,33 años de edad, y de la misma forma, el segundo molar permanente es el que cierra todo el proceso eruptivo. Se adjuntan tablas para complementar la secuencia eruptiva