Controlled cavity collapse: scaling laws of drop formation

The formation of transient cavities at liquid interfaces occurs in an immense variety of natural processes, among which the bursting of surface bubbles and the impact of a drop on a liquid pool are salient. The collapse of a surface liquid cavity is a well documented natural process that leads to the ejection of a thin and fast jet. Droplets generated through this process can be one order of magnitude smaller than the cavity's aperture, and they are consequently of interest in drop on demand inkjet applications. In this work, the controlled formation and collapse of a liquid cavity is analyzed, and the conditions for minimizing the resulting size and number of ejected drops are determined. The experimental and numerical models are simple and consist of a liquid reservoir, a nozzle plate with the discharge orifice, and a moving piston actuated by single half-sine-shaped pull-mode pulses. The size of the jetted droplet is described by a physical model resulting in a scaling law that is numerically and experimentally validated

Scaling properties of protein family phylogenies

One of the classical questions in evolutionary biology is how evolutionary processes are coupled at the gene and species level. With this motivation, we compare the topological properties (mainly the depth scaling, as a characterization of balance) of a large set of protein phylogenies with a set of species phylogenies. The comparative analysis shows that both sets of phylogenies share remarkably similar scaling behavior, suggesting the universality of branching rules and of the evolutionary processes that drive biological diversification from gene to species level. In order to explain such generality, we propose a simple model which allows us to estimate the proportion of evolvability/robustness needed to approximate the scaling behavior observed in the phylogenies, highlighting the relevance of the robustness of a biological system (species or protein) in the scaling properties of the phylogenetic trees. Thus, the rules that govern the incapability of a biological system to diversify are equally relevant both at the gene and at the species level.Comment: Replaced with final published versio

Stability of a rivulet flowing in a microchannel

publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved

Les micromàquines : l'alternativa per les PME

Partint de l'evident interès que per a les petites i mitjanes empreses presenta actualment un projecte d'automatitzar la seva estructura de gestió, tractarem de presentar breument algunes consideracions generals que ajuden a abordar el problema de seleccionar material microinformàtic.Postprint (published version