Breakup of liquid filaments.

Whether a thin filament of liquid separates into two or more droplets or eventually condenses lengthwise to form a single larger drop depends on the liquid's density, viscosity, and surface tension and on the initial dimensions of the filament. Surface tension drives two competing processes, pinching-off and shortening, and the relative time scales of these, controlled by the balance between capillary and viscous forces, determine the final outcome. Here we provide experimental evidence for the conditions under which a liquid filament will break up into drops, in terms of a wide range of two dimensionless quantities: the aspect ratio of the filament and the Ohnesorge number. Filaments which do not break up into multiple droplets demand a high liquid viscosity or a small aspect ratio.This work was supported by EPSRC (RG53364 and RG55605

Heat to electricity thermoacoustic-magnetohydrodynamic conversion

In this work, a new concept for the conversion of heat into electricity is presented. The conversion is based on the combined effects of a thermoacoustic prime mover coupled with a magnetohydrodynamic generator, using different working fluids in each process. The results of preliminary experiments are also presented.Comment: Short article, 5 figures, 5 page

Remedy for Now but Prohibit for Tomorrow: The Deterrence Effects of Merger Policy Tools

Antitrust policy involves not just the regulation of anti-competitive behavior, but also an important deterrence effect. Neither scholars nor policymakers have fully researched the deterrence effects of merger policy tools, as they have been unable to empirically measure these effects. We consider the ability of different antitrust actions – Prohibitions, Remedies, and Monitorings – to deter firms from engaging in mergers. We employ cross-jurisdiction/pan-time data on merger policy to empirically estimate the impact of antitrust actions on future merger frequencies. We find merger prohibitions to lead to decreased merger notifications in subsequent periods, and remedies to weakly increase future merger notifications: in other words, prohibitions involve a deterrence effect but remedies do not

Remedy for Now but Prohibit for Tomorrow: The Deterrence Effects of Merger Policy Tools

Antitrust policy involves not just the regulation of anti-competitive behavior, but also an important deterrence effect. Neither scholars nor policymakers have fully researched the deterrence effects of merger policy tools, as they have been unable to empirically measure these effects. We consider the ability of different antitrust actions - Prohibitions, Remedies, and Monitorings - to deter firms from engaging in mergers. We employ cross-jurisdiction/pan-time data on merger policy to empirically estimate the impact of antitrust actions on future merger frequencies. We find merger prohibitions to lead to decreased merger notifications in subsequent periods, and remedies to weakly increase future merger notifications: in other words, prohibitions involve a deterrence effect but remedies do not. ZUSAMMENFASSUNG - (Auflagen heute, Untersagung morgen: Abschreckungswirkung von Wettbewerbs-intrumenten) Wettbewerbspolitik ist nicht nur Regulierung von wettbewerbsfeindlichem Verhalten, sondern hat auch eine wesentliche Abschreckungswirkung. Weder Wissenschaftler noch politische Entscheidungsträger haben die Abschreckungswirkung von Wettbewerbspolitik vollständig untersucht, da es sehr schwierig ist diese Wirkung empirisch nachzuweisen. Wir untersuchen die Wirkung verschiedener wettbewerbspolitischer Maßnahmen - Untersagung, Auflagen und Monitoring - um Unternehmen von Zusammenschlüssen abzuhalten. Wir nutzen einen Panel-Datensatz, um den Einfluss von Wettbewerbspolitik auf die künftige Anzahl von Firmenzusammenschlüssen zu bewerten. Wir zeigen, dass die Untersagung von Zusammenschlüssen die Fusionsankündigung in der Zukunft reduziert, und dass Fusionsauflagen künftige Ankündigungen schwach ansteigen lassen. Anders gesagt: Untersagungen haben eine führen zu Abschreckungswirkung, Auflagen nicht.merger policy tools, deterrence effects, cross-section/time-series data

Remedy for Now but Prohibit for Tomorrow: The Deterrence Effects of Merger Policy Tools

Antitrust policy involves not just the regulation of anti-competitive behavior, but also an important deterrence effect. Neither scholars nor policymakers have fully researched the deterrence effects of merger policy tools, as they have been unable to empirically measure these effects. We consider the ability of different antitrust actions – Prohibitions, Remedies, and Monitorings – to deter firms from engaging in mergers. We employ cross-jurisdiction/pan-time data on merger policy to empirically estimate the impact of antitrust actions on future merger frequencies. We find merger prohibitions to lead to decreased merger notifications in subsequent periods, and remedies to weakly increase future merger notifications: in other words, prohibitions involve a deterrence effect but remedies do not.

Reynolds number and Shallow Depth Sloshing

The dependence on the Reynolds number of shallow depth sloshing flows inside rectangular tanks subjected to forced harmonic motion is studied in this paper with weakly compressible SPH. We are interested in assessing the in fluenceof viscous effects on the dynamics of shallow depth sloshing flows by using an SPH solver and by comparing with a Navier-Stokes level-set solver results. The goal of trying to model these viscous flows is compromised by the resolution requested due to their Reynolds number, if boundary layer effects are to be modeled. The convenience and feasibility of the implementation of free-slip and no-slip boundary conditions is also discusse

Parameters of oxidative stress in saliva from patients with aggressive and chronic periodontitis

Objectives: Free radicals play an important role in the onset and progression of many diseases. The aim ofthis study was to investigate the contribution of oxidative stress in the pathology of aggressive (AgP) andchronic (CP) periodontitis and its relation with the clinical periodontal status.Methods: Eighty subjects were divided into two groups: 20 patients with AgP and 20 patients with CP withtheir 20 corresponding matched controls, based on clinical attachment loss (CAL), probing pocket depth(PPD), and bleeding on probing (BOP). Saliva reactive oxygen species (ROS), lipid peroxidation, and nonenzymaticantioxidant defences were measured by luminol-dependent chemiluminescence assay, asthiobarbituric acid-reactive substances (TBARs) and total radical-trapping antioxidant potential (TRAP),respectively. Pearson?s correlation and multivariate analysis were used to determine the relationshipbetween ROS and TBARs and the clinical parameters.Results: ROS and TBARs were increased in AgP while TRAP was decreased, comparing with CP. In AgP, astrong and positive correlation was observed between ROS and TBARs and they were closely associatedwith CAL and PPD.Discussion: In AgP, but not in CP, oxidative stress is a high contributor to periodontal pathology and it isclosely associated with the clinical periodontal status.Fil: Acquier, Andrea Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: de Couto Pita, Alejandra Karina. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Farmacología; ArgentinaFil: Busch, Lucila. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Farmacología; ArgentinaFil: Sanchez, Gabriel A.. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Biofísica; Argentin

Dynamic nozzles for drop generators

received: 2015-06-03 accepted: 2015-10-16 published: 2015-11-03received: 2015-06-03 accepted: 2015-10-16 published: 2015-11-03This work was funded by the UK Engineering and Physical Sciences Research Council (Grant No. EP/H018913/1), the John Fell Oxford University Press Research Fund, and the Royal Society

Dynamics of wrinkling in ultrathin elastic sheets

The wrinkling of thin elastic objects provides a means of generating regular patterning at small scales in applications ranging from photovoltaics to microfluidic devices. Static wrinkle patterns are known to be governed by an energetic balance between the object's bending stiffness and an effective substrate stiffness, which may originate from a true substrate stiffness or from tension and curvature along the wrinkles. Here we investigate dynamic wrinkling, induced by the impact of a solid sphere onto an ultra-thin polymer sheet floating on water. The vertical deflection of the sheet's centre induced by impact draws material radially inwards, resulting in an azimuthal compression that is relieved by the wrinkling of the entire sheet. We show that this wrinkling is truly dynamic, exhibiting features that are qualitatively different to those seen in quasi-static wrinkling experiments. Moreover, we show that the wrinkles coarsen dynamically because of the inhibiting effect of the fluid inertia. This dynamic coarsening can be understood heuristically as the result of a dynamic stiffness, which dominates the static stiffnesses reported thus far, and allows new controls of wrinkle wavelength.Comment: 8 pages, 4 figures. Please see published version for supplementary movies and SI Appendi