Axillary vein spasm during cardiac implantable electronic device implantation

Background: The technique of axillary vein (AV) or subclavian vein (SV) puncture has become an important alternative to cephalic vein (CV) cutdown as an approach allowing cardiac lead introduction into the venous system during cardiac implantable electronic device (CIED) implantation procedures. Irrespective of the technique used, the injury associated with lead insertion may induce a reflex venous spasm that can even cause total venous obstruction. In order to assess the incidence of AV spasm during AV puncture, we analysed a total of 735 (382 in females and 353 in males; mean age 75 ± 11 years) de novo CIED implantation procedures involving transvenous lead insertion conducted between January 2014 and December 2015. Materials and methods: In 337 patients the leads were introduced via AV puncture only, in 66 patients AV puncture was used in combination with CV cutdown, together yielding a total of 403 procedures (55% of all de novo CIED implantation procedures; mean patient age 72 ± 14 years), out of which we observed 12 cases (mean patient age 57 ± 25 years) of AV spasm (3%). Results: We evaluated only the procedures with unambiguous fluoroscopy images recorded during AV puncture: complete blockage of contrast medium flow through the AV, with preserved flow through the CV or collateral vessels, followed by eventually resumed flow of contrast via the AV. The contrast-enhanced movements of AV walls showed the spasm propagating both proximally and distally along the vessel, while the subsequent vessel wall relaxation occurred along the entire spasm-affected venous segment simultaneously. Conclusions: An AV spasm induced by AV puncture during CIED implantation is a rare phenomenon; however, if severe, it may significantly affect the course of the procedure

The Martian Photoelectron Boundary as Seen by MAVEN

Photoelectron peaks in the 20â 30 eV energy range are commonly observed in the planetary atmospheres, produced by the intense photoionization from solar 30.4 nm photons. At Mars, these photoelectrons are known to escape the planet down its tail, making them tracers for the atmospheric escape. Furthermore, their presence or absence allow to define the soâ called photoelectron boundary (PEB), which separates the photoelectron dominated ionosphere from the external environment. We provide here a detailed statistical analysis of the location and properties of the PEB based on the Mars Atmosphere and Volatile EvolutioN (MAVEN) electron and magnetic field data obtained from September 2014 to May 2016 (including 1696 PEB crossings). The PEB appears as mostly sensitive to the solar wind dynamic and crustal fields pressures. Its variable altitude thus leads to a variable wake cross section for escape (up to â ¼+50%), which is important for deriving escape rates. The PEB is not always sharp and is characterized on average by the following: a magnetic field topology typical for the end of magnetic pileup region above it, more fieldâ aligned fluxes above than below, and a clear change of the altitude slopes of both electron fluxes and total density (that appears different from the ionopause). The PEB thus appears as a transition region between two plasma and fields configurations determined by the draping topology of the interplanetary magnetic field around Mars and much influenced by the crustal field sources below, whose dynamics also impacts the estimated escape rate of ionospheric plasma.Key PointsWe determined the influence of the main driving parameters on the altitude of the photoelectron boundary (PEB)We identified clear plasma and magnetic field characteristics of the PEB and discuss its nature with respect to the ionopauseWe show how the PEB dynamics modifies the tail cross section used for estimating the photoelectrons (and associated ions) escape ratePeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139944/1/jgra53813_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139944/2/jgra53813.pd

Altitude dependence of nightside Martian suprathermal electron depletions as revealed by MAVEN observations

The MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft is providing new detailed observations of the Martian ionosphere thanks to its unique orbital coverage and instrument suite. During most periapsis passages on the nightside ionosphere suprathermal electron depletions were detected. A simple criterion was implemented to identify the 1742 depletions observed from 16 November 2014 to 28 February 2015. A statistical analysis reveals that the main ion and electron populations within the depletions are surprisingly constant in time and altitude. Absorption by CO2 is the main loss process for suprathermal electrons, and electrons that strongly peaked around 6 eV are resulting from this interaction. The observation of depletions appears however highly dependent on altitude. Depletions are mainly located above strong crustal magnetic sources above 170 km, whereas the depletions observed for the first time below 170 km are globally scattered onto the Martian surface with no particular dependence on crustal fields

MAVEN and MEX multi‐instrument study of the dayside of the Martian induced magnetospheric structure revealed by pressure analyses

International audienceA combination of statistical studies and 18 case studies have been used to investigate the structure of the induced Martian magnetosphere. The different plasma and magnetic pressure forces on the dayside of the induced magnetosphere of Mars have been studied using 3.5 years of Mars Atmosphere and Volatile Evolution (MAVEN) and Mars Express (MEX) observations. We present estimates of typical values for the dominant pressure terms, i.e., the thermal pressures of the ionosphere and the magnetosheath, the magnetic pressure of the magnetic pile‐up region, and the solar wind dynamic pressure. For 18 typical orbits the altitudes and relative distances of the pressure balance boundaries, the photoelectron boundary (PEB), the ion composition boundary (ICB), and the induced magnetosphere boundary (IMB) are estimated. The Magnetic Pile‐up Boundary (MPB) is discussed but not further studied since earlier characterisations of the MPB do not agree with our results.This study focuses on the transition region between the ionosphere and the magnetosheath on the dayside of Mars. We show that earlier definitions of the PEB, ICB, and IMB do not characterise the transition region well, mainly because each boundary is based on measurements from only one or two instruments. In order to characterise the transition region correctly changes in magnetic field strength and fluctuations, dominant ion species, electron and ion densities and energy distributions, need to be considered. This article confirms a complex interaction between Mars and the solar wind and can explain why previous studies have had difficulties to describe the force balance

Comparative study of the Martian suprathermal electron depletions based on Mars Global Surveyor, Mars Express, and Mars Atmosphere and Volatile EvolutioN mission observations

International audienceNightside suprathermal electron depletions have been observed at Mars by three spacecraft to date: Mars Global Surveyor, Mars Express, and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. This spatial and temporal diversity of measurements allows us to propose here a comprehensive view of the Martian electron depletions through the first multispacecraft study of the phenomenon. We have analyzed data recorded by the three spacecraft from 1999 to 2015 in order to better understand the distribution of the electron depletions and their creation mechanisms. Three simple criteria adapted to each mission have been implemented to identify more than 134,500 electron depletions observed between 125 and 900 km altitude. The geographical distribution maps of the electron depletions detected by the three spacecraft confirm the strong link existing between electron depletions and crustal magnetic field at altitudes greater than 170 km. At these altitudes, the distribution of electron depletions is strongly different in the two hemispheres, with a far greater chance to observe an electron depletion in the Southern Hemisphere, where the strongest crustal magnetic sources are located. However, the unique MAVEN observations reveal that below a transition region near 160-170 km altitude the distribution of electron depletions is the same in both hemispheres, with no particular dependence on crustal magnetic fields. This result supports the suggestion made by previous studies that these low-altitudes events are produced through electron absorption by atmospheric CO2

Comparative study of the Martian suprathermal electron depletions based on Mars Global Surveyor, Mars Express, and Mars Atmosphere and Volatile EvolutioN mission observations

International audienceNightside suprathermal electron depletions have been observed at Mars by three spacecraft to date: Mars Global Surveyor, Mars Express, and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. This spatial and temporal diversity of measurements allows us to propose here a comprehensive view of the Martian electron depletions through the first multispacecraft study of the phenomenon. We have analyzed data recorded by the three spacecraft from 1999 to 2015 in order to better understand the distribution of the electron depletions and their creation mechanisms. Three simple criteria adapted to each mission have been implemented to identify more than 134,500 electron depletions observed between 125 and 900 km altitude. The geographical distribution maps of the electron depletions detected by the three spacecraft confirm the strong link existing between electron depletions and crustal magnetic field at altitudes greater than 170 km. At these altitudes, the distribution of electron depletions is strongly different in the two hemispheres, with a far greater chance to observe an electron depletion in the Southern Hemisphere, where the strongest crustal magnetic sources are located. However, the unique MAVEN observations reveal that below a transition region near 160-170 km altitude the distribution of electron depletions is the same in both hemispheres, with no particular dependence on crustal magnetic fields. This result supports the suggestion made by previous studies that these low-altitudes events are produced through electron absorption by atmospheric CO2

Prospects for advanced electron cyclotron resonance and electron beam ion source charge breeding methods for EURISOL

International audienceAs the most ambitious concept of isotope separation on line (ISOL) facility, EURISOL aims at producing unprecedented intensities of post-accelerated radioactive isotopes. Charge breeding, which transforms the charge state of radioactive beams from 1+ to an n+ charge state prior to postacceleration, is a key technology which has to overcome the following challenges: high charge states for high energies, efficiency, rapidity and purity. On the roadmap to EURISOL, a dedicated R&D is being undertaken to push forward the frontiers of the present state-of-the-art techniques which use either electron cyclotron resonance or electron beam ion sources. We describe here the guidelines of this R&D