Unconditional jetting

Capillary jetting of a fluid dispersed into another immiscible phase is usually limited by a critical Capillary number, a function of the Reynolds number and the fluid properties ratios. Critical conditions are set when the minimum spreading velocity of small perturbations $v^*_-$ along the jet (marginal stability velocity) is zero. Here we identify and describe parametrical regions of high technological relevance, where $v^*_- > 0$ and the jet flow is always supercritical independently of the dispersed liquid flow rate: within these relatively broad regions, the jet does not undergo the usual dripping-jetting transition, so that either the jet can be made arbitrarily thin (yielding droplets of any imaginably small size), or the issued flow rate can be made arbitrarily small. In this work, we provide illustrative analytical studies of asymptotic cases for both negligible and dominant inertia forces. In this latter case, requiring a non-zero jet surface velocity, axisymmetric perturbation waves ``surf'' downstream for all given wave numbers while the liquid bulk can remain static. In the former case (implying small Reynolds flow) we found that the jet profile small slope is limited by a critical value; different published experiments support our predictions.Comment: Submitted first (24-August-2008) to Physics of Fluids, withdrawn from that journal on 6-April-2008, and submitted to Physical Review E the same da

The scaling of exploding liquid jets under intense X-ray pulses

A general scaling of the evolution of an exploding liquid jet under an ultra short and intense X-ray pulse from a X-ray free electron laser (XFEL) is proposed. A general formulation of the conservation of energy for blasts in vacuum partially against a deformable object leads to a compact expression that governs the evolution of the gap produced by the explosion. The theoretical analysis contemplates two asymptotic stages for small and large times from the initiation of the blast. A complete dimensional analysis of the problem and an optimal collapse of experimental data reveal that the universal approximate analytical solution proposed is in remarkable agreement with experiments

Scaling laws of top jet drop size and speed from bubble bursting including gravity and inviscid limit

Jet droplets from bubble bursting are determined by a limited parametrical space: the liquid properties (surface tension, viscosity, and density), mother bubble size and acceleration of gravity. Thus, the two resulting parameters from dimensional analysis (usually, the Ohnesorge and Bond numbers, Oh and Bo) completely define this phenomenon when both the trapped gas in the bubble and the environment gas have negligible density. A detailed physical description of the ejection process to model both the ejected droplet radius and its initial launch speed is provided, leading to a scaling law including both Oh and Bo. Two critical values of Oh determine two limiting situations: one (Oh$_1$=0.038) is the critical value for which the ejected droplet size is minimum and the ejection speed maximum, and the other (Oh$_2$=0.0045) is a new critical value which signals when viscous effects vanish. Gravity effects (Bo) are consistently introduced from energy conservation principles. The proposed scaling laws produce a remarkable collapse of published experimental measurements collected for both the ejected droplet radius and ejection speed.Comment: 14 pages, three figures, published in 2018 in Physical Review Fluid

Rutinas y destrezas de pensamiento como propuesta de trabajo para el aprendizaje basado en proyectos en Educación Infantil

En el presente Trabajo de Fin de Grado, pretendemos reflejar la importancia del uso de metodologías activas en la etapa de Educación Infantil, y más concretamente, del Aprendizaje Basado en Proyectos, que ayuda a que el aprendizaje del alumnado sea más significativo, al ser ellos quienes lo construyen por si solos. Así como manifestar la necesidad de que se entrene el pensamiento a estas edades, por lo que es imprescindible trabajar rutinas y destrezas de pensamiento para incrementar las capacidades de crítica, análisis y creatividad del alumnado ante el mundo que le rodea. También, gracias a la propuesta de intervención educativa llevada a cabo, podemos afirmar que el Aprendizaje Basado en Proyectos y el entrenamiento del pensamiento son muy apropiados para trabajar en Educación Infantil de manera globalizada y vivencial, haciendo que el aprendizaje del alumnado sea lo más óptimo e íntegro posible, y sepan compartirlo de manera apropiada.Grado en Educación Infanti

Risk stratifiers for arrhythmic and non-arrhythmic mortality after acute myocardial infarction

Open Access. Publicado online: 2-Jul-2018The effective discrimination between patients at risk of Arrhythmic Mortality (AM) and Non-Arrhythmic Mortality (NAM) constitutes one of the important unmet clinical needs. Successful risk assessment based on Electrocardiography (ECG) records is greatly improved by the combination of different indices reflecting not only the pathological substrate but also the autonomic regulation of cardiac electrophysiology. This study assesses the cardiac risk stratification capacity of two new Heart Rate Variability (HRV) parameters, Breath Concurrence 6 (BC6) -sinusoidal RR variability of 6 heart beats per breath cycle- and Primary Ectopia (PE) -presence of early ventricular contractions of any etiology- together with the Deceleration Capacity (DC). While BC6 characterizes the response to physiological and pathophysiological stimuli, PE qualifies autonomic cardiac electrophysiology. The analysis of the European Myocardial Infarct Amiodarone Trial (EMIAT) database indicates that BC6 is related with the risk of Arrhythmic Mortality (AM) and PE with the risk of Non-Arrhythmic Mortality. BC6 is the only single parameter that significantly discriminates between AM and NAM. While the combination of BC6 and DC contributes to the identification of AM risk, PE together with DC improves the prediction of NAM in patients with severe ischemic heart disease

Los contratos de consumo en la jurisprudencia del TJUE. Últimas tendencias

The concept of “consumer” is, in theory, a restrictive concept. However, the ECJ has now extended it to cases in which a private individual has gone on to practice as a professional in an manifest, public and conspicuous manner. Judgment ECJ 25 January 2018, C-498/16, Facebook proves it. In relation to consumers of financial products, the ECJ skillfully pulls strings in the context of art. 7.2 BR I-bis; however, that norm is totally insensitive with regards to the consumer. The future is stepping forward towards online mass consumption, and in the present virtual social landscape it is necessary for the ECJ to open up new ways of protecting the consumer that keep up with times. In this context, it is necessary that future amendments to the Brussels I-bis Regulation incorporate the concepts that the ECJ has created in relation to jurisdiction in the cross-border consumer sector: the concepts of “act of consumption”, “consumer”, “professional”, and “directed activity”, for example, should stop being jurisprudential concepts to become legal concepts.El concepto de “consumidor” es, en teoría, un concepto restrictivo. Sin embargo, el TJUE lo ha extendido a casos en los que un particular, en el momento presente, ha pasado a ejercer como profesional de manera evidente, pública y notoria. La STJUE 25 enero 2018, C-498/16, Facebook, es la prueba. En relación con los consumidores de productos financieros, el TJUE mueve sus hilos con destreza en el contexto del art. 7.2 RB I-bis, pero este precepto es totalmente insensible al consumidor. El futuro camina digitalmente hacia un consumo masivo online y en dicho paisaje social virtual es necesario que el TJUE abra vías de protección al consumidor de un modo evolutivo. En dicho contexto, es preciso que futuras reformas del Reglamento Bruselas I-bis incorporen los conceptos que el TJUE ha creado en relación con la competencia judicial en el sector del consumo transfronterizo: los conceptos de “acto de consumo”, “consumidor”, “profesional”, y “actividad dirigida”, por ejemplo, deberían dejar de ser conceptos jurisprudenciales para pasar a ser conceptos legales

A revision on Rayleigh capillary jet breakup

The average Rayleigh capillary breakup length of a cylindrical Newtonian viscous liquid jet moving with homogeneous velocity $\hat{U}$ (negligible external forces) must be determined by the selection of normal modes with time-independent amplitude and wavelength (invariant modes, IMs). Both positive and negative group velocity IMs exist in ample ranges of the parameter domain (Weber and Ohnesorge numbers), which explains (i) the average breakup length independence on ambient conditions (long-term resonance), and (ii) its proportionality to the inverse of the spatial growth rate of the dominant positive group velocity IM. Published experimental results since Grace (1965, PhD Thesis) confirm our proposal.Comment: 9 pages, 7 figure

Arroyo Aparicio, Alicia, Contrato de Agencia: principios y análisis

This article reviews: Arroyo Aparicio, Alicia, Contrato de Agencia: principios y análisis, Aranzadi, 2019, 1ª edición, 160 páginas. Prólogo de Alberto Bercovitz Rodríguez-Can

Gómez Jene, Miguel, International Commercial Arbitration in Spain

This article reviews: Gómez Jene, Miguel, International Commercial Arbitration in Spain, Wolters Kluwer International, The Netherlands, 2019, 380 pp

Generation of Steady Liquid Microthreads and Micron-Sized Monodisperse Sprays in Gas Streams

A new class of microscopic jet flows is here reported: for a certain range of physical parameters and geometrical configurations, a perfectly steady microscopic liquid thread can be formed by a laminar accelerating gas stream, eventually giving rise to a nearly monodisperse fine spray. Some interesting characteristics for many applications of this robust and versatile flow and related atomization technique are highlighted. Concentric multicomponent liquid threads can also be produced. A theoretical model is presented that shows agreement with experiments.Spanish Comisión Interministerial de Ciencia y Tecnología PB93-1181Spanish Comisión Interministerial de Ciencia y Tecnología PB96-134