Respiratory adverse events associated with deep propofol sedation during upper gastrointestinal procedures in children

Background/Aims: Upper airway stimulation with endoscopes and pH-impedance probes during deep propofol sedation confers unknown risk for associated respiratory adverse airway events. This report quantifies frequencies of such events and airway rescue interventions associated with Esophagogastroduodenoscopies (EGD) and multi-channel intraluminal acid detection impedance probe (MIIP) placements. Methods: This was a prospective observational study regarding occurrence of adverse respiratory events in 42 children undergoing propofol sedated EGDs and MIIP placements: Group 1. (n=21 EGDs), Group2 (n=21 EGDs before MIIP), Group 3. (n=21 during MIIP). Results: All procedures were successfully completed using deep propofol sedation. Respiratory events were transient and associated with no morbidity or mortality. Nearly half of each group experienced a respiratory event. “Partial airway obstruction” during 42 EGDs occurred in 28.6% and responded to simple airway interventions. “Complete airway obstruction” occurred during 1/42 EGDs and 2/21 MIIPs. Throughout MIIP placement, endoscopic visualization of the glottis was maintained and unnecessary stimulation of the glottis was avoided; nonetheless, complete airway obstruction occurred in 2/21. Advanced airway rescue maneuvers were not required in either instance. Conclusions: Respiratory adverse events commonly occurred during EGDs and MIIP placements. All events were successfully rescued by simple airway interventions.

Measurement of volume fraction of air in water: experimental Study

In multi phase mixing of flow streams, the measurement of fraction of individual components with consideration of proportion of volume need to be analyzed considering the serious issues in many chemical and other processing industries. Even though, quantifiable measurements technique are exist for the calculation of solubility, partial pressure, molar fraction and VOF, the VOF measurement is the meaningful measure of percentage fraction of air in water. In this experimental procedure, the method to resolve the Volume fraction (VOF) is discussed and the same is achieved by impedance probe method.

The challenges of the Dust-Field-Plasma (DFP) instrument onboard ESA Comet Interceptor mission

<p>The flyby of a dynamically new comet by ESA-F1 Comet Interceptor spacecraft offers unique multi-point opportunities for studying the comet's dusty and ionised cometary  environment in ways that were not possible with previous missions, including Rosetta. As Comet Interceptor is an F-class mission, the payload is limited in terms of mass, power, and heritage. Most in situ science sensors therefore have been tightly integrated into a single Dust-Field-Plasma (DFP) instrument on the main spacecraft A and on the ESA sub-spacecraft B2, while there is a Plasma Package suite on the JAXA second sub-spacecraft B1. The advantage of tight integration is an important reduction of mass, power, and especially complexity, by keeping the electrical and data interfaces of the sensors internal to the DFP instrument.</p><p>The full diagnostics located on the board of the 3 spacecrafts will allow  to modeling the comet environment and described the complex physical processes around the comet and on their surface including also the  description of wave particle  interaction in dusty cometary plasma. </p><p>The full set of DFP instrument on  board the Comet Interceptor  spacecraft will allow to model  the comet plasma environment and its interaction with the solar wind. It will also allow to describe the complex physical processes taking place including wave particle  interaction in dusty cometary plasma . </p><p>On spacecraft A, DFP consists of a magnetometer, a Langmuir and multi impedance probe/electric field instrument, an ion and an electron analyzer, a dust sensor, and a central data processing unit and electronics box. On spacecraft B2, the instrumentation is limited to a magnetometer and a dust sensor. The choice of sensors and their capabilities are such that it maximizes synergies and complementarities. </p><p>To give one example: While the dust instrument aims at establishing the dust spectrum for millimeter to micrometer sized particles, the Langmuir probes aided by the data processing unit will analyze the signatures of micrometer to nanometer sized particles.</p><p>Moreover, unique multi-point measurements will be obtained from magnetometers on the three spacecraft, from dust sensors on A and B2, and from ion measurements on A and B1.</p><p>The tight integration of dust-field-plasma sensor hardware and science targets embodied by DFP promises an optimized science return for the available resources.</p>

Electron cooling at a weakly outgassing comet

<p>The Rosetta spacecraft arrived at comet 67P in August 2014 and then escorted it for 2 years along its orbit. Throughout this escort phase, two plasma instruments (Mutual Impedance Probe, MIP; and Langmuir Probe, LAP) measured a population of cold electrons (< 1 eV) within the coma of 67P (Engelhardt et al., 2018; Wattieaux et al, 2020; Gilet et al., 2020). These cold electrons are understood to be formed by cooling warm electrons through collisions with the neutral gas. The warm electrons are primarily newly-born and produced at roughly 10eV within the coma through ionisation. While it was no surprise that cold electrons would form near perihelion given the high density of the neutral coma, the persistence of the cold electrons up to a heliocentric distance of 3.8 au was highly unexpected. With the low outgassing rates observed at such large heliocentric distances (Q < 10<sup>26</sup> s<sup>-1</sup>), there should not be enough neutral molecules to cool the warm electrons efficiently before they ballistically escape the coma.</p><p>We use a collisional test particle model to examine the formation of the cold electron population at a weakly outgassing comet. The electrons are subject to stochastic collisions with the neutral coma which can either scatter or cool the electrons. Multiple electron neutral collision processes are included such that the electrons can undergo elastic scattering as well as collisions inducing excitation and ionisation of the neutral species. The inputted electric and magnetic fields, which act on the test particles, are taken from a 3D fully-kinetic, collisionless Particle-in-Cell (PiC) model of the solar wind and cometary ionosphere (Deca et al., 2017; 2019), with the same neutral coma as used in our model. We use a pure water coma with spherical symmetry and a 1/r<sup>2</sup> dependence in the neutral number density to drive the production of cometary electrons and the electron-neutral collisions.</p><p>We first demonstrate the trapping of electrons in a potential well around the comet nucleus, formed by an ambipolar field. We show how this electron-trapping process can lead to more efficient cooling of electrons and the subsequent formation of a cold electron population, even at low outgassing rates.</p>

Ion bulk speeds and temperatures in the diamagnetic cavity of comet 67P

<p>The formation and maintenance of the diamagnetic cavity around comets is a debated subject. For active comets such as 1P/Halley, the ion-neutral drag force is suggested to balance the outside magnetic pressure at the cavity boundary, but measurements made by Rosetta at the intermediately active comet 67P/Churyumov-Gerasimenko indicate that the situation might be different at less active comets. Measurements from the Langmuir probes and the Mutual Impedance Probe on board Rosetta, as well as modelling efforts, show ion velocities significantly above the velocity of the neutral particles, indicating that the ions are not as strongly coupled to the neutrals at comet 67P.</p><p>In this study we use low-energy high time resolution data from the Ion Composition Analyzer (ICA) on Rosetta to determine the bulk speeds and temperatures of the ions inside the diamagnetic cavity of comet 67P. The interpretation of the low-energy data is not straight forward due to the complicated influence of the spacecraft potential, but a newly developed method utilizing simulations with the Spacecraft Plasma Interaction Software (SPIS) software makes it possible to extract the original properties of the ion distribution. We use SPIS to model the influence of the spacecraft potential on the energy spectrum of the ions, and fit the energy spectrum sampled by ICA to the simulation results. This gives information about both the bulk speed and temperature of the ions.</p><p>The results show bulk speeds of 5-10 km/s, significantly above the speed of the neutral particles, and temperatures of 0.7-1.6 eV. The major part of this temperature is attributed to ions being born at different locations in the coma, and could hence be considered a dispersion rather than a temperature in the classical sense. The high bulk speeds support previous results, indicating that the collisional coupling between ions and neutrals is weak inside the diamagnetic cavity.</p>

Cooling of Electrons in a Weakly Outgassing Comet

<p>The plasma instruments, Mutual Impedance Probe (MIP) and Langmuir Probe (LAP), part of the Rosetta Plasma Consortium (RPC), onboard the Rosetta mission to comet 67P revealed a population of cold electrons (<1eV) (Engelhardt et al., 2018; Wattieaux et al, 2020; Gilet et al., 2020). This population is primarily generated by cooling warm (~10eV) newly-born cometary electrons through collisions with the neutral coma. What is surprising is that the cold electrons were detected throughout the escort phase, even at very low outgassing rates (Q<1e26 s<sup>-1</sup>) at large heliocentric distances (>3 AU), when the coma was not thought to be dense enough to cool the electron population significantly.</p> <p> Using a collisional test particle model, we examine the behaviour of electrons in the coma of a weakly outgassing comet and the formation of a cold population through electron-neutral collisions. The model incorporates three electron sources: the solar wind, photo-electrons produced through ionisation of the cometary neutrals by extreme ultraviolet solar radiation, and secondary electrons produced through electron-impact ionisation.</p> <p>The model includes different electron-water collision processes, including elastic, excitation, and ionisation collisions.</p> <p> The electron trajectories are shaped by electric and magnetic fields, which are taken from a 3D collisionless fully-kinetic Particle-in-Cell (PIC) model of the solar wind and cometary plasma  (Deca 2017, 2019). We use a spherically symmetric coma of pure water, which gives a r<sup>-2</sup> profile in the neutral density. Throughout their lifetime, electrons undergo stochastic collisions with neutral molecules, which can degrade the electrons in energy or scatter them.</p> <p>We first validate our model with comparison to results from PIC simulations. We then demonstrate the trapping of electrons in the coma by an ambipolar electric field and the impact of this trapping on the production of cold electrons.</p>