First observations and performance of the RPW instrument onboard the Solar Orbiter mission

The Radio and Plasma Waves (RPW) instrument on the ESA Solar Orbiter mission is designed to measure in situ magnetic and electric fields and waves from the continuum up to several hundred kHz. The RPW also observes solar and heliospheric radio emissions up to 16 MHz. It was switched on and its antennae were successfully deployed two days after the launch of Solar Orbiter on February 10, 2020. Since then, the instrument has acquired enough data to make it possible to assess its performance and the electromagnetic disturbances it experiences. In this article, we assess its scientific performance and present the first RPW observations. In particular, we focus on a statistical analysis of the first observations of interplanetary dust by the instrument’s Thermal Noise Receiver. We also review the electro-magnetic disturbances that RPW suffers, especially those which potential users of the instrument data should be aware of before starting their research work

Erratum: The solar orbiter radio and plasma waves (RPW) instrument (Astronomy and Astrophysics (2020) 642 (A12) DOI: 10.1051/0004-6361/201936214)

The erratum concerns Fig. 9 entitled "Antenna radio-electrical properties" for which some of the parameters are not correct. The new figure with new parameters is provided in Fig. 1 of this corrigendum. Fig. 1. Corrected Antenna radio-electrical properties. (Figure Presented)

Development of a physiologically based toxicokinetic model for butadiene and four major metabolites in humans : global sensivity analysis for experimental design issues

International audience1,3-Butadiene (BD) is metabolized in humans and rodents to mutagenic and carcinogenic species. Our previous work has focused on developing a physiologically based toxicokinetic (PBTK) model for BD to estimate its metabolic rate to 1,2-epoxy-3-butene (EB), using exhaled breath BD concentrations in human volunteers exposed by inhalation. In this paper, we extend our BD model to describe the kinetics of its four major metabolites EB, 1,2:3,4-diepoxybutane (DEB), 3-butene-1,2-diol (BDD), and 3,4-epoxy-1,2-butanediol (EBD), and to test whether the extended model and experimental data (to be collected for BD and metabolites in humans) are together adequate to estimate the metabolic rate constants of each of the above chemicals. Global sensitivity analyses (GSA) were conducted to evaluate the relative importance of the model parameters on model outputs during the 20 min of exposure and the 40 min after exposure ended. All model parameters were studied together with various potentially measurable model outputs: concentrations of BD and EB in exhaled air, concentrations of BD and all metabolites in venous blood, and cumulated amounts of urinary metabolites excreted within 24 h. Our results show that pulmonary absorption of BD and subsequent distribution and metabolism in the well-perfused tissues compartment are the critical processes in the toxicokinetics of BD and metabolites. In particular, three parameters influence numerous outputs: the blood:air partition coefficient for BD, the metabolic rate of BD to EB, and the volume of the well-perfused tissues. Other influential parameters include other metabolic rates, some partition coefficients, and parameters driving the gas exchanges (in particular, for BD outputs). GSA shows that the impact of the metabolic rate of BD to EB on the BD concentrations in exhaled air is greatly increased if a few of the model's important parameters (such as the blood:air partition coefficient for BD) are measured experimentally. GSA also shows that all the transformation pathways described in the PBTK model may not be estimable if only data on the studied outputs are collected, and that data on a specific output for a chemical may not inform all the transformations involving that chemical. (C) 2007 Elsevier Ireland Ltd. All rights reserved

Observation of Intensified Lower Hybrid Noise in the Midlatitude Ionosphere

International audienceWe report DEMETER observations of strongly intensified electric noise at the lower hybrid frequency in the midlatitude ionosphere during the recovery phase of a magnetic storm. The spectrum of the noise is broadband and centered at the lower hybrid frequency, which is of a very unusual shape that suggests nonlinear interaction triggered by the injection of ring current ions into the ionosphere

Development and application of generic toxicokinetic models in fish to environmental risk assessment of chemicals

One of the goals of environmental risk assessment is to protect animal populations and the whole ecosystem from adverse effects resulting from exposure to single or multiple chemicals. In principle, risk assessment methodologies rely on combining estimates of exposure to the chemical(s) with toxicity data (hazard) used for risk characterisation. Exposure assessment aims to quantify “external dose”, as the amount of chemical agent(s) that reaches an organism. Hazard assessment for a chemical aims to quantify the relationship between dose and toxicity so that reference points can be set to derive environmental standards for specific protection goals. Over the last two decades, many research efforts have aimed to improve the quantification of such dose response relationships through the integration of “external dose” and “internal dose” namely toxicokinetic (TK)/ADME (Absorption, Distribution, Metabolism, and Excretion) processes. For this purpose, TK models have been developed to estimate internal doses from external doses in a time dependent manner, characterise the consequence of metabolism to identify the toxic species for a given compound (parent compound/metabolite) as well as extrapolate between laboratory and environmental conditions or between species. The purpose of this project is to develop a generic TK model for fish species to predict internal doses under different environmental scenarios of exposure. The model will be adaptable to a number of teleost fish species and validated by using data for studies on regulated products (e.g. pesticides) and environmental contaminants. Extensive literature searches will be performed to review models and tools incorporating TK for environmental risk assessment, collect biological and physiological parameters for given fish species and TK parameters for chemicals of environmental relevance. From this data collection exercise, tools aiming at predicting TK parameters for a number of fish species (i.e. interspecies extrapolation) will be developed. These tools will allow the calibration of fish physiologically-based TK (PB-TK) model taking into account several compartments (e.g. liver, fat) to model ADME processes for chemicals under different exposure scenarios. Finally, the predictive ability of the model and the uncertainties will be assessed for both TK parameters taking into account fish species differences and prediction of toxicity parameters

Quantifying heterogeneity in exposure-risk relationships using exhaled breath biomarkers for 1, 3-butadiene exposure

International audienceThe health effects of human exposure to 1,3-butadiene (BD) have been extensively studied using both epidemiological and animal toxicology approaches. However, various data and knowledge gaps remain, one of which is an understanding of the human heterogeneity in BD dosimetry. The objective of our study was to better understand the role of individual variability in delivered tissue dose. We designed a study of laboratory exposures of a relatively large group of healthy human subjects. Subjects were then exposed to 2.0 ppm BD through a face mask for 20 min, followed by 40 min of breathing clean air. Exhaled breath concentrations of BD were measured at ten time points during and after exposure, and a three-compartment physiologically based pharmacokinetic (PBPK) model was used to quantify the kinetic behavior of BD. We implemented a Markov chain Monte Carlo procedure to fit the model to the experimental data, and used global sensitivity analysis techniques to examine the sensitivity of exhaled breath concentrations to PBPK model parameters. Uptake during exposure was strongly influenced by rebreathing of exhaled BD during exposure; inclusion of rebreathing in the model simulations resulted in a 21% increase in the amount of BD retained in the body. We found that uptake ranged from 38% to 77% across individuals. We measured considerable intra-individual variability from 11 subjects who underwent the testing twice. Most of this variation stemmed from phase I metabolism of BD, which varied by as much as a factor of 2.6 within individuals. Overall, we have sought to quantify the sources of inter- and intra-individual variabilities in the pharmacokinetic behavior of BD. The results of our research may impact the current framework for biomarker and pharmacokinetic studies by improving our understanding of the sources of heterogeneity in response to chemical exposures

Unexpected Very Low Frequency (VLF) Radio Events Recorded by the Ionospheric Satellite DEMETER

International audienceDEMETER was a low Earth orbiting microsatellite in operation between July 2004 and December 2010. Its scientific objective was the study of ionospheric perturbations in relation to seismic activity and man-made activities. Its payload was designed to measure electromagnetic waves over a large frequency range as well as ionospheric plasma parameters (electron and ion densities, fluxes of energetic charged particles). This paper will show both expected and unusual events recorded by the satellite when it was in operation. These latter events have been selected from the DEMETER database because they are rare or even have never been observed before, because they have a very high intensity, or because they are related to abnormalities of the experiments under particular plasma conditions. Some events are related to man-made radio waves emitted by VLF ground-based transmitters or power line harmonic radiation. Natural waves, such as atypical quasi-periodic emissions or uncommon whistlers, are also shown

ICE, the Electric Field instrument on Demeter.

International audienceThe objective of the ICE (Instrument Champ Electrique) experiment on board DEMETER is to provide a nearly continuous survey of the electromagnetic and/or electrostatic waves that may arise from the coupling of seismic activity with the upper atmosphere and ionosphere. To this aim it makes use of 4 spherical electrodes with embedded preamplifiers that are deployed by stacer booms at approximately 4 in from the satellite. Measurements are made over a wide frequency range from DC to 3.175 MHz, subdivided in the signal processing unit in four frequency channels DC/ULF, ELF, VLF and HF. Three axis measurements are available in the DC/ULF range for all modes of operation of DEMETER and in the ELF range in the DEMETER Burst modes. In the VLF and HF ranges and in ELF during DEMETER Survey modes only one axis of measurement is available that can be selected by telecommand. We present in this paper a general description of the instrument and its modes of operation and in-flight performances. The sensitivity is similar to 0.1-0.2 mu V/mHz(1/2) from similar to 100 Hz through the HF range and the dynamical range is > 80 dB in ELF and VLF and about 42 dB in HF. In order to illustrate the instrument capabilities, we briefly describe a number of observations from the first months of operation in various regions along the orbit from the equator to high latitudes