BepiColombo is a joint mission between the European Space Agency, ESA, and the Japanese Aerospace Exploration Agency, JAXA, to perform a comprehensive exploration of Mercury. Launched on
20
th
...October 2018 from the European spaceport in Kourou, French Guiana, the spacecraft is now en route to Mercury.
Two orbiters have been sent to Mercury and will be put into dedicated, polar orbits around the planet to study the planet and its environment. One orbiter, Mio, is provided by JAXA, and one orbiter, MPO, is provided by ESA. The scientific payload of both spacecraft will provide detailed information necessary to understand the origin and evolution of the planet itself and its surrounding environment. Mercury is the planet closest to the Sun, the only terrestrial planet besides Earth with a self-sustained magnetic field, and the smallest planet in our Solar System. It is a key planet for understanding the evolutionary history of our Solar System and therefore also for the question of how the Earth and our Planetary System were formed.
The scientific objectives focus on a global characterization of Mercury through the investigation of its interior, surface, exosphere, and magnetosphere. In addition, instrumentation onboard BepiColombo will be used to test Einstein’s theory of general relativity. Major effort was put into optimizing the scientific return of the mission by defining a payload such that individual measurements can be interrelated and complement each other.
•We present the main characteristics of ISA accelerometer (Italian Spring Accelerometer), a tri-axial electro-mechanical accelerometer for space use, to be embarked on-board the BepiColombo mission ...towards the Mercury planet (2017).•We depict the issue of the zero-g positioning for the accelerometer, i.e. the measure of the sensing mass rest position when the sensor is in free-fall conditions (named briefly zero-g), condition that would be observed in orbit.•We present an experimental procedure and a zero-g facility to measure the zero-g positioning verified on DM and EQM models of ISA.•We show some results of tests carried out on an EQM model of ISA
BepiColombo is a joint ESA/JAXA mission devoted to study the planet Mercury through two orbiters (MPO and MMO) to be launched in 2017. Among the main objectives, the European MPO aims at measuring the gravitational field of Mercury with unprecedented accuracy, through a careful reconstruction of the spacecraft orbit. The use of a very high sensitive tri-axial accelerometer, named ISA, will improve the orbital determination through an accurate sensing of the non-gravitational accelerations experienced by the spacecraft, mainly due to the solar radiation.
The development of the three accelerometers, aluminium-made and constituted by electro-mechanical transducers, faced different issues to reach the required performance.
One of the most relevant topic was the zero-g positioning, i.e. the measure of the sensing mass rest position when the sensor is in free-fall conditions (named briefly zero-g), condition that would be observed in orbit. The sensor offers the best performance when the sensing mass operates around this equilibrium position. Therefore this position needs to be identified and the mass has to be located there to guarantee the requirements imposed by the measurement of the non-gravitational accelerations. The group of Experimental Gravitation at IAPS/INAF in Rome developed an experimental procedure and a set-up to measure the zero-g position, carrying out a measurement campaign. This procedure will be applied to measure the zero-g positioning of ISA flight models.
The Radio Science Experiments of the BepiColombo mission will enable substantial improvement of the knowledge of Mercury's orbit and rotation, and the relativistic dynamics in the solar system. A ...fundamental support to the spacecraft tracking data will be given by the Italian Spring Accelerometer (ISA). This is a three-axis accelerometer devoted to the measurement of the non-gravitational perturbations acting on the Mercury Planetary Orbiter (MPO), whose knowledge is important in order to fully exploit the quality of the tracking data. The intrinsic noise level of the instrument that will be onboard MPO,
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frequency range, guarantees the fulfilment of the RSE requirements. The main scientific and technological features of the instrument are discussed, together with its current error budget, experimental activities and foreseen calibration strategies.
La Société de réanimation de langue française et la Société française de médecine d’urgence ont décidé d’élaborer de nouvelles recommandations sur la prise en charge de l’état mal épileptique (EME) ...avec l’ambition de répondre le plus possible aux nombreuses questions pratiques que soulèvent les EME : diagnostic, enquête étiologique, traitement non spécifique et spécifique. Vingt-cinq experts ont analysé la littérature scientifique et formulé des recommandations selon la méthodologie GRADE. Les experts se sont accordés sur 96 recommandations. Les recommandations avec le niveau de preuve le plus fort ne concernent que l’EME tonico-clonique généralisé (EMTCG) : l’usage des benzodiazépines en première ligne (clonazépam en intraveineux direct ou midazolam en intramusculaire) est recommandé, répété 5 min après la première injection (à l’exception du midazolam) en cas de persistance clinique. En cas de persistance 5 min après cette seconde injection, il est proposé d’administrer la seconde ligne thérapeutique : valproate de sodium, (fos-)phénytoïne, phénobarbital ou lévétiracétam. La persistance avérée de convulsions 30 min après le début de l’administration du traitement de deuxième ligne signe l’EMETCG réfractaire. Il est alors proposé de recourir à un coma thérapeutique au moyen d’un agent anesthésique intraveineux de type midazolam ou propofol. Des recommandations spécifiques à l’enfant et aux autres EME sont aussi énoncées.
Management of status epilepticus (SE) is subject to many difficulties: diagnosis, etiological investigation, non-specific and specific treatment. The French Society of Intensive Care and the French Society of Emergency Medicine, with the French Group for Pediatric Intensive Care and Emergencies, have developed guidelines to respond to the practical questions raised by SE management in the prehospital setting, in the emergency department and in the intensive care unit. Twenty-five experts analyzed the literature and formulated recommendations according to the Grade of Recommendation Assessment, Development and Evaluation methodology. The experts agreed on 96 recommendations. Recommendations with the strongest level of evidence concern only generalized tonic convulsive SE. In this setting, first-line use of benzodiazepines (direct intravenous clonazepam or intramuscular midazolam) was recommended, with a second injection in the case of clinical persistence of SE five minutes after the first injection. In the case of persistence of SE five minutes after this second injection, the recommendation is to administer the second-line treatment: sodium valproate, (fos)phenytoin, phenobarbital or levetiracetam. The confirmed persistence of convulsions 30 min after the beginning of the administration of this second-line treatment defines refractory SE. At this stage, a coma should be rapidly induced by means of a third-line general anesthetic (midazolam and/or propofol). Additional specific recommendations focus on children (except newborns) and on other types of SE.
We present here the concept for a new experimental test of the Weak Equivalence Principle (WEP) carried out in the gravity field of the Sun. The WEP, stating the independence of the gravitational ...acceleration a body is subject to from its mass and composition, is at the basis of general relativity theory and more in general of metric theories of gravitation. It is therefore very important to test it to the precision allowable by current technology. The experiment here proposed aims at measuring the relative acceleration of two test masses in free fall, searching for a possible violation of the WEP, which would show up as a non-zero acceleration signal. The core of the experiment is constituted by a differential accelerometer with zero baseline, whose central elements are two test masses of different materials. This differential accelerometer is placed on a pendulum, in such a way as to make the common center of mass coincident with the center of mass of the pendulum itself. Ensuring a very precise centering, such a system should provide a high degree of attenuation of the local seismic noise, which — together with an integration time of the order of tens of days — would allow a test of the WEP with an accuracy improved by at least an order of magnitude with respect to the best measurements achieved so far. One of the strengths of this proposal is the know-how acquired from a previous study and technology development (GReAT: General Relativity Accuracy Test) that involved a test of the WEP in the gravity field of the Earth, in free fall inside a co-moving capsule released from a stratospheric balloon. The concept of the experiment is introduced, with particular attention to the differential accelerometer and its accommodation on the pendulum. A preliminary estimate of the attainable precision is given, along with a critical analysis of the associated challenges.
Abstract
Aims
Out-of-hospital cardiac arrest (OHCA) without return of spontaneous circulation (ROSC) despite conventional resuscitation is common and has poor outcomes. Adding extracorporeal membrane ...oxygenation (ECMO) to cardiopulmonary resuscitation (extracorporeal-CPR) is increasingly used in an attempt to improve outcomes.
Methods and results
We analysed a prospective registry of 13 191 OHCAs in the Paris region from May 2011 to January 2018. We compared survival at hospital discharge with and without extracorporeal-CPR and identified factors associated with survival in patients given extracorporeal-CPR. Survival was 8% in 525 patients given extracorporeal-CPR and 9% in 12 666 patients given conventional-CPR (P = 0.91). By adjusted multivariate analysis, extracorporeal-CPR was not associated with hospital survival odds ratio (OR), 1.3; 95% confidence interval (95% CI), 0.8–2.1; P = 0.24. By conditional logistic regression with matching on a propensity score (including age, sex, occurrence at home, bystander CPR, initial rhythm, collapse-to-CPR time, duration of resuscitation, and ROSC), similar results were found (OR, 0.8; 95% CI, 0.5–1.3; P = 0.41). In the extracorporeal-CPR group, factors associated with hospital survival were initial shockable rhythm (OR, 3.9; 95% CI, 1.5–10.3; P = 0.005), transient ROSC before ECMO (OR, 2.3; 95% CI, 1.1–4.7; P = 0.03), and prehospital ECMO implantation (OR, 2.9; 95% CI, 1.5–5.9; P = 0.002).
Conclusions
In a population-based registry, 4% of OHCAs were treated with extracorporeal-CPR, which was not associated with increased hospital survival. Early ECMO implantation may improve outcomes. The initial rhythm and ROSC may help select patients for extracorporeal-CPR.
Status epilepticus (SE) refractory to benzodiazepines and other antiepileptic agents is managed with intravenous anesthetic compounds, such as thiopental, propofol or midazolam. These drugs display ...quite different pharmacodynamic and pharmacokinetic properties, but have not been prospectively compared to date. Their use is clearly advocated for the treatment of generalized convulsive SE, whereas partial-complex, or absence SE are generally managed less aggressively, in consideration of their better prognosis. The most important aspect seems to be related to the correct use of these anesthetics in the right context, rather than the choice of one specific compound. An electroencephalographic burst-suppression should be targeted for about 24 hour, before progressive weaning of the dosage under EEG monitoring. If this approach proves unsuccessful, the use of other drugs, including inhalational anesthetics, has been described.
Noninvasive ventilation (NIV) is increasingly used in patients with acute respiratory distress syndrome (ARDS). The evidence supporting NIV use in patients with ARDS remains relatively sparse.
To ...determine whether, during NIV, the categorization of ARDS severity based on the Pa
/Fi
Berlin criteria is useful.
The LUNG SAFE (Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure) study described the management of patients with ARDS. This substudy examines the current practice of NIV use in ARDS, the utility of the Pa
/Fi
ratio in classifying patients receiving NIV, and the impact of NIV on outcome.
Of 2,813 patients with ARDS, 436 (15.5%) were managed with NIV on Days 1 and 2 following fulfillment of diagnostic criteria. Classification of ARDS severity based on Pa
/Fi
ratio was associated with an increase in intensity of ventilatory support, NIV failure, and intensive care unit (ICU) mortality. NIV failure occurred in 22.2% of mild, 42.3% of moderate, and 47.1% of patients with severe ARDS. Hospital mortality in patients with NIV success and failure was 16.1% and 45.4%, respectively. NIV use was independently associated with increased ICU (hazard ratio, 1.446 95% confidence interval, 1.159-1.805), but not hospital, mortality. In a propensity matched analysis, ICU mortality was higher in NIV than invasively ventilated patients with a Pa
/Fi
lower than 150 mm Hg.
NIV was used in 15% of patients with ARDS, irrespective of severity category. NIV seems to be associated with higher ICU mortality in patients with a Pa
/Fi
lower than 150 mm Hg. Clinical trial registered with www.clinicaltrials.gov (NCT 02010073).
The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while ...transiting by their suns. Then the instrument had to be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude M
v
= 9–12 and to see contrasts of the order of 10
−4
–10
−5
necessary to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR is a spectrometer in a cross-dispersed configuration, covering the 0.4–2.5 μm spectral range with a resolving power of about 330 and a field of view of 2 arcsec. It is functionally split into two channels respectively working in the 0.4–1.0 μm and 1.0–2.5 μm spectral ranges. Such a solution is imposed by the fact the light at short wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The spectrometer makes use of a HgCdTe detector of 512 by 512 pixels, 18 μm pitch and working at a temperature of 45 K as the entire VNIR optical bench. The instrument has been interfaced to the telescope optics by two optical fibers, one per channel, to assure an easier coupling and an easier colocation of the instrument inside the EChO optical bench.
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