On turbulent entrainment and dissipation in dilute polymer solutions

We present a comparative experimental study of a turbulent flow developing in clear water and dilute polymer solutions (25 and 50 wppm polyethylene oxide). The flow is forced by a planar grid that oscillates vertically with stroke S and frequency f in a square container of initially still fluid. Two-component velocity fields are measured in a vertical plane passing through the center of the tank by using time resolved particle image velocimetry. After the forcing is initiated, a turbulent layer develops that is separated from the initially irrotational fluid by a sharp interface, the so-called turbulent/nonturbulent interface (TNTI). The turbulent region grows in time through entrainment of surrounding fluid until the fluid in the whole container is in turbulent motion. From the comparison of the experiments in clear water and polymer solutions we conclude: (i) Polymer additives modify the large scale shape of the TNTI. (ii) Both, in water and in the polymer solution the mean depth of the turbulent layer, H(t), follows the theoretical prediction for Newtonian fluids H(t)∞√Kt, where K∞S^2f is the “grid action.” (iii) We find a larger grid action for dilute polymer solutions than for water. As a consequence, the turbulent kinetic energy of the flow increases and the rate of energy input becomes higher. (iv) The entrainment rate β=v_e/v_(rms) (where v_e=dH/dt is the interface propagation velocity and v_(rms) is the root mean square of the vertical velocity) is lower for polymers (β_p≈0.7) than for water (β_w≈0.8). The measured values for β are in good agreement with similarity arguments, from which we estimate that in our experiment about 28% of the input energy is dissipated by polymers

The Effect of Group Identity on Distributive Choice : Social Preference or Heuristic?

Group identity can influence significantly people's attitudes toward monetary allocations. In this paper we reassess the representation of group identity using social preference models. First, we show that the influence of group identity varies unsystematically across different types of mini-dictator games and cannot be described using a well-behaved preference function. Second, we demonstrate that the effect is not robust to slightly increasing the complexity of the task, suggesting that group identity is a framing effect that can be easily displaced by alternative decision heuristics

Viscous tilting and production of vorticity in homogeneous turbulence

Viscous depletion of vorticity is an essential and well known property of turbulent flows, balancing, in the mean, the net vorticity production associated with the vortex stretching mechanism. In this letter, we, however, demonstrate that viscous effects are not restricted to a mere destruction process, but play a more complex role in vorticity dynamics that is as important as vortex stretching. Based on the results from three dimensional particle tracking velocimetry experiments and direct numerical simulation of homogeneous and quasi-isotropic turbulence, we show that the viscous term in the vorticity equation can also locally induce production of vorticity and changes of the orientation of the vorticity vector (viscous tilting)

La enseñanza del cálculo en la educación polimodal y en la universidad: diagnóstico sobre números reales

Los alumnos ingresantes a nuestra universidad muestran déficit en lo referido a competencias y a contenidos disciplinares básicos de Matemática. Considerando esta realidad y la importancia que tiene el Cálculo como materia básica, nos propusimos llevar a cabo el Proyecto: La Enseñanza del Cálculo. Articulación entre el Nivel Polimodal y el Nivel Universitario, con el fin de identificar obstáculos, que dificultan la comprensión de los conceptos fundamentales de este campo conceptual, para generar estrategias que contribuyan al mejoramiento de su enseñanza y de su aprendizaje. Como metodología de investigación y para guiar tanto las experiencias en clase como para estudiar los resultados de enseñanza, utilizaremos una ingeniería didáctica. En el marco de la etapa de análisis preliminar que estamos transitando, nos referiremos al análisis e interpretación de los datos obtenidos en una de las instancias de diagnóstico en la que abordamos el contenido: Números Reales

Characterizing the cardiovascular functions during atrial fibrillation through lumped-parameter modeling

Atrial fibrillation (AF), causing irregular and rapid heartbeats, is the most common arrhythmia. Due to the widespread impact on the population and the disabling symptoms related to rapid heart rate, AF is a subject of growing interest under several aspects: statistical analyses on the heartbeat distributions, risk factors, impact on quality of life, correlation with other cardiac pathologies. However, several key points on the consequences induced by AF on the cardiovascular system are still not completely understood. The proposed work aims at quantifying the impact of AF on the most relevant cardiovascular parameters by means of a lumped-parameter modeling, paying particular attention to the stochastic nature of the irregular heartbeats and the reduced contractility of the heart. The global response leads to a rather impressive overall agreement with the clinical state-of-the-art measures regarding AF: reduced cardiac output with correlated arterial hypotension, as well as higher left atrial volume and pressure values are some of the most representative outcomes emerging during AF. Moreover, new insights on hemodynamic parameters such as cardiac flow rates, which are difficult to measure and almost never offered in literature, are here provided

Patient satisfaction and food waste in obstetrics and gynaecology wards

Introduction: Patient satisfaction is an indicator of healthcare quality, and expectation is an important determinant. A component of patient satisfaction is the quality of foodservice. An indicator of this quality is the food wasted by hospitalised patients. In the present study, we investigated patient satisfaction regarding food and foodservice, the expectation on food quality and the amount of food wasted in two obstetrics and gynaecology wards in Northern and Southern Italy. Patients and Methods: A questionnaire, including sociodemographic data, rate of food waste, expectations of food quality and characteristics of food and foodservice, was admini-strated to 550 inpatients in obstetrics and gynaecology wards (275 for each hospital). Univariate analysis was performed to describe the results, and multivariate analysis was carried out to control for sociodemographic data. Results: Northern patients were more satisfied with the quality of food (54.2% vs 36.0%) and foodservice (54.5% vs 38.2%) than southern patients. Northern patients had more positive expectations about the quality of food (69.5% vs 31.6%), whereas southern patients stated that they had no expectations. Southern patients gave more importance to mealtime (72.7% vs 26.2%), and many of them brought food from home to the hospital (30.2% vs 2.2%) through relatives who came to visit them. Southern patients discarded about 41.7% of food served, whereas northern patients discarded only about 15.3%. Discussion: Food waste is a worldwide problem due to its economic, social and environmental effects. Especially in hospitals, food waste could have a negative impact on the overall patient satisfaction

A practical overview of image classification with variational tensor-network quantum circuits

Circuit design for quantum machine learning remains a formidable challenge. Inspired by the applications of tensor networks across different fields and their novel presence in the classical machine learning context, one proposed method to design variational circuits is to base the circuit architecture on tensor networks. Here, we comprehensively describe tensor-network quantum circuits and how to implement them in simulations. This includes leveraging circuit cutting, a technique used to evaluate circuits with more qubits than those available on current quantum devices. We then illustrate the computational requirements and possible applications by simulating various tensor-network quantum circuits with PennyLane, an open-source python library for differential programming of quantum computers. Finally, we demonstrate how to apply these circuits to increasingly complex image processing tasks, completing this overview of a flexible method to design circuits that can be applied to industrially-relevant machine learning tasks

Combining 4D Flow MRI and Complex Networks Theory to Characterize the Hemodynamic Heterogeneity in Dilated and Non-dilated Human Ascending Aortas

Motivated by the evidence that the onset and progression of the aneurysm of the ascending aorta (AAo) is intertwined with an adverse hemodynamic environment, the present study characterized in vivo the hemodynamic spatiotemporal complexity and organization in human aortas, with and without dilated AAo, exploring the relations with clinically relevant hemodynamic and geometric parameters. The Complex Networks (CNs) theory was applied for the first time to 4D flow magnetic resonance imaging (MRI) velocity data of ten patients, five of them presenting with AAo dilation. The time-histories along the cardiac cycle of velocity-based quantities were used to build correlation-based CNs. The CNs approach succeeded in capturing large-scale coherent flow features, delimiting flow separation and recirculation regions. CNs metrics highlighted that an increasing AAo dilation (expressed in terms of the ratio between the maximum AAo and aortic root diameter) disrupts the correlation in forward flow reducing the correlation persistence length, while preserving the spatiotemporal homogeneity of secondary flows. The application of CNs to in vivo 4D MRI data holds promise for a mechanistic understanding of the spatiotemporal complexity and organization of aortic flows, opening possibilities for the integration of in vivo quantitative hemodynamic information into risk stratification and classification criteria

Comparative interactomics with Funcoup 2.0

FunCoup (http://FunCoup.sbc.su.se) is a database that maintains and visualizes global gene/protein networks of functional coupling that have been constructed by Bayesian integration of diverse high-throughput data. FunCoup achieves high coverage by orthology-based integration of data sources from different model organisms and from different platforms. We here present release 2.0 in which the data sources have been updated and the methodology has been refined. It contains a new data type Genetic Interaction, and three new species: chicken, dog and zebra fish. As FunCoup extensively transfers functional coupling information between species, the new input datasets have considerably improved both coverage and quality of the networks. The number of high-confidence network links has increased dramatically. For instance, the human network has more than eight times as many links above confidence 0.5 as the previous release. FunCoup provides facilities for analysing the conservation of subnetworks in multiple species. We here explain how to do comparative interactomics on the FunCoup website