Interfacial areas and gas hold-ups in bubble columns and packed bubble columns at elevated pressures

Interfacial areas and gas hold-ups have been determined at pressures up to 1.85 MPa in a bubble column with a diameter of 85.5 mm and for superficial gas velocities between 1 and 10 cm s−1. In some experiments the bubble column was packed with glass cylinders of length 5.0 mm and diameter 4.0 mm. The interfacial areas were determined by the chemical method using the model reaction between CO2 and aqueous diethanolamine (DEA) and hold-ups by observation of height differences.\ud \ud The interfacial areas in the packed bubble column are unaffected by pressure. The gas hold-ups as well as the interfacial areas in the bubble column increase with increasing operating pressure. The magnitude of the pressure influence depends on the superficial gas velocity. The positive influence of pressure on the gas hold-ups and the interfacial in the bubble column originates from the formation of smaller bubbles at the gas distributor

Ion cyclotron wall conditioning experiments on Tore Supra in presence of the toroidal magnetic field

Wall conditioning techniques applicable in the presence of the high toroidal magnetic field will be required for the operation of ITER for tritium removal, isotopic ratio control and recovery to normal operation after disruptions. Recently ion cyclotron wall conditioning (ICWC) experiments have been carried out on Tore Supra in order to assess the efficiency of this technique in ITER relevant conditions. The ICRF discharges were operated in He/H-2 Mixtures at the Tore Supra nominal field (3.8 T) and a RF frequency of 48 MHz, i.e. within the ITER operational space. RF pulses of 60 s (max.) were applied using a standard Tore Supra two-strap resonant double loop antenna in ICWC mode, operated either in pi or 0-phasing with a noticeable improvement of the RF coupling in the latter case. In order to assess the efficiency of the technique for the control of isotopic ratio the wall was first preloaded using a D-2 glow discharge. After 15 minutes of ICWC in He/H-2 gas mixtures the isotopic ratio was altered from 4% to 50% at the price of an important H implantation into the walls. An overall analysis comparing plasma production and the conditioning efficiency as a function of discharge parameters is given

Dissecting bombs and bursts: non-LTE inversions of low-atmosphere reconnection in SST and IRIS observations

Ellerman bombs and UV bursts are transient brightenings that are ubiquitously observed in the lower atmospheres of active and emerging flux regions. Here we present inversion results of SST/CRISP and CHROMIS, as well as IRIS data of such transient events. Combining information from the Mg II h & k, Si IV and Ca II 8542A and Ca II H & K lines, we aim to characterise their temperature and velocity stratification, as well as their magnetic field configuration. We find average temperature enhancements of a few thousand kelvin close to the classical temperature minimum, but localised peak temperatures of up to 10,000-15,000 K from Ca II inversions. Including Mg II generally dampens these temperature enhancements to below 8000 K, while Si IV requires temperatures in excess of 10,000 K at low heights, but may also be reproduced with secondary temperature enhancements of 35,000-60,000 K higher up. However, reproducing Si IV comes at the expense of overestimating the Mg II emission. The line-of-sight velocity maps show clear bi-directional jet signatures and strong correlation with substructure in the intensity images, with slightly larger velocities towards the observer than away. The magnetic field parameters show an enhancement of the horizontal field co-located with the brightenings at similar heights as the temperature increase. We are thus able to largely reproduce the observational properties of Ellerman bombs with UV burst signature with temperature stratifications peaking close to the classical temperature minimum. Correctly modelling the Si IV emission in agreement with all other diagnostics is, however, an outstanding issue. Accounting for resolution differences, fitting localised temperature enhancements and/or performing spatially-coupled inversions is likely necessary to obtain better agreement between all considered diagnostics.Comment: Accepted for publication in Astronomy & Astrophysics. 24 pages, 17 figure

Gene induction during differentiation of human monocytes into dendritic cells: an integrated study at the RNA and protein levels

Changes in gene expression occurring during differentiation of human monocytes into dendritic cells were studied at the RNA and protein levels. These studies showed the induction of several gene classes corresponding to various biological functions. These functions encompass antigen processing and presentation, cytoskeleton, cell signalling and signal transduction, but also an increase in mitochondrial function and in the protein synthesis machinery, including some, but not all, chaperones. These changes put in perspective the events occurring during this differentiation process. On a more technical point, it appears that the studies carried out at the RNA and protein levels are highly complementary.Comment: website publisher: http://www.springerlink.com/content/ha0d2c351qhjhjdm

Determining the effect of three- dimensional printing orientation on the bending strength of sand moulds and cores when using a voxeljet additive manufacturing machine

Abstract: Advances made in Additive Manufacturing (AM) or 3D printing led to the 3D printing of sand moulds and cores used in the foundry industry. Ideally, the mechanical properties of the 3D printed moulds and cores should be uniform throughout the 3D printed part. This will ensure that the casting produced from the 3D printed mould has uniform properties throughout the mould. The following study investigated the effect of the printing location and part orientation in the AM machine used to produce the 3D Printed mould on the bending strength property of sand parts. Several printing orientations and angles were considered in the investigation. Descriptive statistics was used to assess and interpret the results

High-order aberration compensation with Multi-frame Blind Deconvolution and Phase Diversity image restoration techniques

Context. For accurately measuring intensities and determining magnetic field strengths of small-scale solar (magnetic) structure, knowledge of and compensation for the point spread function is crucial. For images recorded with the Swedish 1-meter Solar Telescope, restoration with Multi-Frame Blind Deconvolution and Joint Phase Diverse Speckle methods lead to remarkable improvements in image quality but granulation contrasts that are too low, indicating additional stray light. Aims. We propose a method to compensate for stray light from high-order atmospheric aberrations not included in MFBD and JPDS processing. Methods. To compensate for uncorrected aberrations, a reformulation of the image restoration process is proposed that allows the average effect of hundreds of high-order modes to be compensated for by relying on Kolmogorov statistics for these modes. The applicability of the method requires simultaneous measurements of Fried's parameter r0. The method is tested with simulations as well as real data and extended to include compensation for conventional stray light. Results. We find that only part of the reduction of granulation contrast in SST images is due to uncompensated high-order aberrations. The remainder is still unaccounted for and attributed to stray light from the atmosphere, the telescope with its re-imaging system and to various high-altitude seeing effects. Conclusions. We conclude that statistical compensation of high-order modes is a viable method to reduce the loss of contrast occurring when a limited number of aberrations is explicitly compensated for with MFBD and JPDS processing. We show that good such compensation is possible with only 10 recorded frames. The main limitation of the method is that already MFBD and JPDS processing introduces high-order compensation that, if not taken into account, can lead to over-compensation.Comment: in press in Astronomy & Astrophysic

Resuscitation of Drowned Persons during the COVID-19 Pandemic: A Consensus Statement

Importance: Resuscitation is a niche example of how the COVID-19 pandemic has affected society in the long term. Those trained in cardiopulmonary resuscitation (CPR) face the dilemma that attempting to save a life may result in their own harm. This is most of all a problem for drowning, where hypoxia is the cause of cardiac arrest and ventilation is the essential first step in reversing the situation. Objective: To develop recommendations for water rescue organizations in providing their rescuers with safe drowning resuscitation procedures during the COVID-19 pandemic. Evidence Review: Two consecutive modified Delphi procedures involving 56 participants from 17 countries with expertise in drowning prevention research, resuscitation, and programming were performed from March 28, 2020, to March 29, 2021. In parallel, PubMed and Google Scholar were searched to identify new emerging evidence relevant to each core element, acknowledge previous studies relevant in the new context, and identify knowledge gaps. Findings: Seven core elements, each with their own specific recommendations, were identified in the initial consensus procedure and were grouped into 4 categories: (1) prevention and mitigation of the risks of becoming infected, (2) resuscitation of drowned persons during the COVID-19 pandemic, (3) organizational responsibilities, and (4) organizations unable to meet the recommended guidelines. The common measures of infection risk mitigation, personal protective equipment, and vaccination are the base of the recommendations. Measures to increase drowning prevention efforts reduce the root cause of the dilemma. Additional infection risk mitigation measures include screening all people entering aquatic facilities, defining criteria for futile resuscitation, and avoiding contact with drowned persons by rescuers with a high-risk profile. Ventilation techniques must balance required skill level, oxygen delivery, infection risk, and costs of equipment and training. Bag-mask ventilation with a high-efficiency particulate air filter by 2 trained rescuers is advised. Major implications for the methods, facilities, and environment of CPR training have been identified, including nonpractical skills to avoid being infected or to infect others. Most of all, the organization is responsible for informing their members about the impact of the COVID-19 pandemic and taking measures that maximize rescuer safety. Research is urgently needed to better understand, develop, and implement strategies to reduce infection transmission during drowning resuscitation. Conclusions and Relevance: This consensus document provides an overview of recommendations for water rescue organizations to improve the safety of their rescuers during the COVID-19 pandemic and balances the competing interests between a potentially lifesaving intervention and risk to the rescuer. The consensus-based recommendations can also serve as an example for other volunteer organizations and altruistic laypeople who may provide resuscitation.. © 2022 American Medical Association. All rights reserved

Inverse Classification for Comparison-based Interpretability in Machine Learning

In the context of post-hoc interpretability, this paper addresses the task of explaining the prediction of a classifier, considering the case where no information is available, neither on the classifier itself, nor on the processed data (neither the training nor the test data). It proposes an instance-based approach whose principle consists in determining the minimal changes needed to alter a prediction: given a data point whose classification must be explained, the proposed method consists in identifying a close neighbour classified differently, where the closeness definition integrates a sparsity constraint. This principle is implemented using observation generation in the Growing Spheres algorithm. Experimental results on two datasets illustrate the relevance of the proposed approach that can be used to gain knowledge about the classifier.Comment: preprin