De Physique Research Articles

A Real-World Study of Nusinersen Effects in Adults with Spinal Muscular Atrophy Type 2 and 3.

Spinal muscular atrophy (SMA) is a progressive genetic disorder characterized by muscle weakness ultimately leading to pulmonary impairments that can be fatal. The recent approval of nusinersen, a disease-modifying therapy, substantially changed the prognosis for patients, particularly in children. However, real-world evidence about its long-term effectiveness in adults remains limited. This study aimed to document longitudinal data on motor function, pulmonary function and patient-reported outcome measures of Canadian adults with SMA type 2 and 3 treated with nusinersen. Outcomes from 17 patients were collected at the Institut de réadaptation en déficience physique de Québec during routine clinical visits over 36 months post nusinersen treatment, using the Hammersmith Functional Motor Scale Expanded for SMA (HFMSE), Revised Upper Limb Module (RULM), 6-Minute Walk Test (6MWT), Children's Hospital of Philadelphia Adult Test of Neuromuscular Disorders (CHOP-ATEND), SMA functional rating scale (SMAFRS), pulmonary function testing and subjective changes reported by patients. After 36 months, 9 patients showed motor function improvement. Changes beyond the minimal clinically important difference were seen for four patients on the HFMSE, four patients on the RULM and five patients on the 6MWT. Pulmonary function remained stable for most subjects. Subjective positive changes were reported in 88% of patients and five patients showed improvement in the SMAFRS. This real-world study demonstrates the positive effects of nusinersen in adults with SMA types 2 and 3. Although stabilizing the patient's condition is considered therapeutic success, this study shows an improvement in motor function and subjective gains in several patients.

Near- to mid-IR spectral purity transfer with a tunable frequency comb: Methanol frequency metrology over a 1.4 GHz span

We report the upgrade and operation of a frequency-comb-assisted high-resolution mid-infrared molecular spectrometer, allowing us to combine high spectral purity, International System of Units (SI)-traceability, wide tunability, and high sensitivity. An optical frequency comb is used to transfer the spectral purity of a SI-traceable 1.54 μm metrology-grade frequency reference to a 10.3 μm quantum cascade laser (QCL). The near-infrared reference is operated at the French time/frequency metrology institute, calibrated there to primary frequency standards, and transferred to Laboratoire de Physique des Lasers via the REFIMEVE fiber network. The QCL exhibits a linewidth of δν ∼ 0.1 Hz and a sub-10−15 relative frequency stability from 0.1 to 10 s, and its frequency is traceable to the SI with a total relative uncertainty better than 4 × 10−14 after 1 s averaging time. We have developed the instrumentation allowing comb modes to be continuously tuned over 9 GHz, resulting in a QCL of record spectral purity uninterruptedly tunable at the precision of the reference over an unprecedented span of Δν = 1.4 GHz. We have used our apparatus to conduct sub-Doppler spectroscopy of methanol in a multi-pass cell, demonstrating state-of-the-art frequency uncertainties down to the few kilohertz level (∼10−10 in relative value). We have observed weak intensity resonances unreported so far, resolved subtle doublets never seen before, and brought to light discrepancies with HITRAN. This demonstrates the potential of our apparatus for probing subtle internal molecular processes, building accurate spectroscopic models of polyatomic molecules of atmospheric or astrophysical interest, and carrying out precise spectroscopic tests of fundamental physics.

Grain boundary diffusion and grain boundary phase transition in tungsten in the temperature range of activated sintering

Abstract Grain boundary self- and solute (cobalt) diffusion in tungsten was found [Lee et al., Scr. Metall, 1988; Lee et al., Col. de Physique, 1990] to exhibit discontinuities in the Arrhenius behavior at the homologous temperatures of 0.36 < T/T m < 0.4 that surprisingly match the activation sintering temperature of W (T m is the melting point). In the present work, this unusual grain boundary diffusion phenomenon is discussed in terms of a fundamental grain boundary phase transition in W. The experimental data are analysed with respect to predicted segregation-induced grain boundary phase transformation. Competing co-segregation of impurity elements (carbon and phosphor) might induce a discontinuous grain boundary segregation and invoke a grain boundary phase transition which modifies the grain boundary mobilities of substitutional atoms. The improved understanding of grain boundary phase transitions is expected to provide a breakthrough in interpreting the exact mechanism of W-activated sintering.

GEOSCOPE Network: 40 Yr of Global Broadband Seismic Data

Abstract The GEOSCOPE observatory (Institut de physique du globe de Paris [IPGP] and École et Observatoire des Sciences de la Terre de Strasbourg, 1982) provides more than four decades of high-quality continuous broadband data to the scientific community. Started in 1982 with only two stations, the network has grown over the years thanks to numerous international partnerships. At present, 34 stations operate in 18 countries across all continents and on islands throughout the oceans, filling important gaps in global Earth coverage. Most of the first installed stations are still running today, allowing for long-term observations, and new sites are being prospected to further improve global coverage. Over the years, GEOSCOPE has contributed to defining today’s global seismology standards (data format, data quality level, instrumentation requirements), being the French contribution to the international effort for global seismic observations. The stations are instrumented with the best quality seismometers (from the very first STS-1 in the early 80s to the last STS-6A and Trillium T360 today) and digitizers (Q330HR and Centaur) to record with high fidelity the ground motions generated by all types of seismic sources. Real-time data are sent to the tsunami warning centers and both validated and real-time data are available at the IPGP, Epos-France and Earthscope data centers. The quality of GEOSCOPE data and metadata is ensured by daily and yearly validation that enables issue detection and mitigation. GEOSCOPE, in collaboration with the other global networks, has played and continues to play a crucial role in the study of Earth’s structure and global dynamics and the characterization of all types of seismic sources.

Realization and simulations of the new SPES Beam Cooler

One of the aim of the new project Selective Production of Exotic Species (SPES) is to produce and select new, neutron reach, isotopes [1,2,3,4]. The technique adopted to produce these species is the Isotope Selection On Line (ISOL) that postpones the separation of the isotopes after the beam production, using a High-Resolution Mass Spectrometer (HRMS).In order to allow a good separation of isotopes , the transverse emittance and the energy spread of the beam should have very low values, for this reason the Beam Cooler (BC) is located between the ISOL target, i.e. the beam source, and the HRMS.In the SPES project, where heavy isotopes are expected (mass number >100), the spectrometer resolution must be preferably higher than dm/m = 5 × 10-5 and thus the features of the beam at the entrance of the HRMS should be at least εn 95% < 8.3 × 10-3 π mm mrad and σE < 1.5 eV.BC devices are devoted to improve the beam features in terms of emittance and energy spread. A new BC has been designed and realized by the Laboratoire de Physique Corpuscolaire (LPC) at Caen, France, for the SPES facility at Laboratori Nazionali di Legnaro (LNL), near Padova, Italy.BCs cool down the beam thanks to a dissipative process in which the thermal energy passes from the beam ions to another medium whose constituent is typically much lighter, Helium gas in our case. This process takes place inside a confinement system that on the one hand to limit the spread of the cooling medium, and on the other to allow the beam to continue along the required trajectory, in the presented device it is a row of radio frequency quadrupoles in an almost closed chamber.Some specifications of the BC described in this document: the RFQ is 723 mm long, its internal radius is 5 mm; the RFQ is included in the gas chamber which is 730 mm×280 mm×220 mm. Before it there is the injection part composed by, following the beam trajectory, a grounded pipe (388 mm long) and three focusing electrodes. On the opposite side there is the extraction part with two focusing electrodes.This document presents the main features of the new BC together with the results of a preliminary study where the beam dynamic has been simulated. The analysis embeds also the investigation of the gas distribution inside and outside the BC.The beam dynamic simulations are based on the Simion code [5] while the estimation of the gas distribution is computed with MolFlow+ [6].Simulations show that accurately setting the BC leads to a large improvement of the emittance while the energy spread still needs to be improved. Limiting the gas pressure in the acceleration zone seems to allow the required final boost.

The 4th Southeast Asian Conference on Geophysics (SEACG) 2022: Great Challenges and Opportunities of Geophysics Today and Future

The Southeast Asian Conference on Geophysics (SEACG) is a biannual event held by the Geophysical Engineering Department, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (ITB), Indonesia. The SEACG has been successfully conducted since 2016, and several selected papers have been published in the IOP Conference Series: Earth and Environmental Science. The first (2016) and second (2018) conferences were held offline in Bali, Indonesia, while the third conference (2020) was held virtually due to the Covid19 pandemic. Along with the end of the Covid19 pandemic, the current event (2022) is being run as a hybrid conference (physical and virtual), live from Bandung, Indonesia.The conference theme of the SEACG 2022 is “Great Challenges and Opportunities of Geophysics Today and Future.” The program lasts two days, from August 9, 2022, to August 10, 2022, and is sponsored by the Institute of Research and Community Services, ITB. There are 11 invited international speakers (30-minute duration) and 88 contributed speakers (20 min duration) who presented their ideas. With five panel rooms, 35 contributed speakers delivered offline presentations and 53 virtually via Zoom. The speakers, both invited and contributed, presented and introduced new geophysical insights and techniques.The panel discussion featured intriguing topics and invited speakers from various institutions, such as Institut Teknologi Bandung – Indonesia (Dr.rer.nat. R. Mohammad Rachmat Sule, Dr. Tedi Yudistira, Prof. Sri Widiyantoro, Prof. Wahyu Srigutomo, and Prof. Wawan Gunawan Abdul Kadir), CSIRO – Australia (Dr. Erdinc Saygin), Australian National University – Australia (Prof. Phil Cummins), University of Tokyo – Japan (Prof. Takeshi Tsuji), JGI, Inc. – Japan (Moeto Fujisawa, M.Sc.), Ocean University of China – China (Dr. Zhijun Du), and Institut de Physique du Globe de Paris – France (Dr. Jean-Philippe Metaxian). The event was opened by Dr. Fatkhan (the Head of the Geophysical Engineering Master and Doctorate Degree Program, ITB) and closed by Dr. Warsa (the Head of the Geophysical Engineering Bachelor Degree Program, ITB).The SEACG 2022 provided a platform for academics, professionals, and students to discuss and promote scientific results related to recent advancements in geophysical methods and related sciences. The conference covered various session topics, such as Fault and Deformation Study, Passive Seismic, Environmental Geophysics, Geophysical Approaches in Hydrocarbon, Geophysical Approaches in Geothermal, Advance Geophysics, Vulcanology, Tomography, Seismic Hazards, Geomagnetic, and Seismology.We would thank the organization’s team members, the reviewers, and the faculty staff. They have worked very hard to make this event possible. We wish all attendees of SEACG 2022 have an exciting experience and enjoy the moment in this scientific forum.List of Organizing Committee, Documentation are available in this pdf.

Impact of radon on personal contamination monitors at the exit of the restricted controlled areas in EDF nuclear power plant

Background: Between 2008 and 2017, EDF has progressively replaced its old Personal Contamination Monitors (PCM) with a new generation to strengthen the control of the workers at the exit of the restricted controlled areas. One of the novelties of the new PCM generation is the introduction of gamma channels which, coupled to the beta channel, allows a more reliable and more precise measurement. The new PCM also includes a better monitoring of the C2 portals alarms triggering system, a greater detection surface to minimize the dead zone and carries out morphological compensation to take into account the attenuation of the gamma background by the body. This new PCM is very efficient and capable of detecting low contamination activities. The sensitivity of this monitoring system is such that the solid progeny of 222Rn deposited on clothes (such as the 214Pb and the 214Po) could in some cases be detected and triggered the C2 portals alarm. Objective: In order to quantify the impact of radon (222Rn) and its progeny on the C2 portals triggers, a specific study has been conducted. Beyond the physical aspect, several purposes are targeted: (1) to provide quantitative explanations about the C2 alarms attributed to radon and determine which channels are more affected by the 222Rn progeny; (2) to determine the existence of a relation between C2 alarms and high 222Rn volume activity; (3) to optimize practices at the exit of the Restricted Controlled Areas (RCA), for example, adapt waiting time before control in PCM. The study consisted in measuring the activity of radon progeny deposited on several types of suits used in EDF Nuclear Power Plants (NPPs). To assess the impact of the 222Rn, several factors have been studied such as the 222Rn exposure time, the 222Rn concentration and the nature of textile fibers constituting clothes. For this study, several facilities from the Laboratoire de Physique des deux infinis de Bordeaux (LP2i Bordeaux) have been used, including a 222Rn emanation standard source and various emanation chambers between 60 L and 750 L. A specific calibration method to characterize radon progenies deposited has been developed (see Sects. 2.4 and 3). The 222Rn concentration in the sample exposure environment is verified both using a commercial (see Sects. 2.4 and 3) and experimental high sensitivity radon detectors. The measurements of the 222Rn progeny on clothes are made immediately after exposure by gamma spectrometry control on a High Purity Germanium (HPGe) detector. This experiment has been carried out at the PRISNA measurement platform (Plateforme Régionale Interdisciplinaire de Spectrométrie Nucléaire en Aquitaine) located in LP2I Bordeaux. Conclusions: In this study, several phenomena have been highlighted for a better understanding of the C2 portal triggering. We validate that in presence of 222Rn volume concentration activity lower than 300 Bq/m3, an alarm in beta channels of C2 portals can be triggered because of the presence of the radon progeny on clothes. The triggering of the gamma channels could appear only if the volume concentration activity of radon is higher than 3000 Bq/m3. The results obtained in this study could led to optimize and harmonize the practices at the exit of Restricted Controlled Area (RCA) like adapt waiting time before control in PCM.

Validation of Aeolus wind profiles using ground-based lidar and radiosonde observations at Réunion island and the Observatoire de Haute-Provence

Abstract. The European Space Agency's (ESA) Aeolus satellite mission is the first Doppler wind lidar in space, operating in orbit for more than 4 years since August 2018 and providing global wind profiling throughout the entire troposphere and the lower stratosphere. The Observatoire de Haute-Provence (OHP) in southern France and the Observatoire de Physique de l'Atmosphère de La Réunion (OPAR) are equipped with ground-based Doppler Rayleigh–Mie lidars, which operate on similar principles to the Aeolus lidar and are among essential instruments within the ESA Aeolus calibration and validation (cal/val) program. This study presents the validation results of the L2B Rayleigh clear horizontal line-of-sight (HLOS) winds from September 2018 to January 2022. The point-by-point validation exercise relies on a series of validation campaigns at both observatories: AboVE (Aeolus Validation Experiment), held in September 2019 and June 2021 at OPAR and in January 2019 and December 2021 at OHP. The campaigns involved time-coordinated lidar acquisitions and radiosonde ascents collocated with the nearest Aeolus overpasses. During AboVE-2, Aeolus was operated in a campaign mode with an extended range bin setting allowing inter-comparisons up to 28.7 km. We show that this setting suffers from larger random error in the uppermost bins, exceeding the estimated error, due to lack of backscatter at high altitudes. To evaluate the long-term evolution in Aeolus wind product quality, twice-daily routine Météo-France radiosondes and regular lidar observations were used at both sites. This study evaluates the long-term evolution of the satellite performance along with punctual collocation analyses. On average, we find a systematic error (bias) of −0.92 and −0.79 m s−1 and a random error (scaled MAD) of 6.49 and 5.37 m s−1 for lidar and radiosondes, respectively.

Angular momentum of doubly magic 132Sn fission product: Experimental and theoretical aspects

Despite the numerous theoretical and experimental works published very recently, the way in which fission fragments acquire their angular momentum is still an open question. This angular momentum generation mechanism is important not only for improving our understanding of the fission process, but also for nuclear energy applications, since the angular momentum of fission fragments strongly impact the prompt gamma spectra and consequently the decay heat in a reactor. In this context, within the framework of a collaboration between the ‘Laboratoire de Physique Subatomique et Corpusculaire’ (LPSC, France), the ‘Institut Laue Langevin’ (ILL, France) and the CEA-Cadarache (France), an experimental program was developed on the LO-HENGRIN mass-spectrometer with the aim of measuring isomeric ratio of some fission products for different thermal-neutron-induced fission reactions. This paper will be focused on the results obtained for the spherical nucleus 132Sn following thermal-neutron-induced fission of both 235U and 241Pu targets. To further challenge the angular momentum generation models, 132Sn isomeric ratio (IR) was measured as a function of 132Sn fission product kinetic energy (KE). The angular momentum was determined by combining our experimental data with the calculations performed with the FIFRELIN Monte Carlo code. A clear angular momentum decrease with KE was observed for both reactions. Lastly, we investigate the dependence of the 132Sn angular momentum with the incident neutron energy, from thermal region up to 5 MeV (below the second-chance fission). For that, the four free available parameters in FIFRELIN are selected in order to reproduce the average prompt neutron multiplicity. In this way, the angular momentum is deduced for each neutron energy. These results are discussed in terms of the impact of the available intrinsic excitation energy at scission on the spin generation mechanism.

Toward Detection of the Molecular Parity Violation in Chiral Ru(acac)3 and Os(acac)3.

We present a theory-experiment investigation of the helically chiral compounds Ru(acac)3 and Os(acac)3 as candidates for next-generation experiments for detection of molecular parity violation (PV) in vibrational spectra. We used relativistic density functional theory calculations to identify optimal vibrational modes with expected PV effects exceeding by up to 2 orders of magnitude the projected instrumental sensitivity of the ultrahigh resolution experiment under construction at the Laboratoire de Physique des Lasers in Paris. Preliminary measurements of the vibrational spectrum of Ru(acac)3 carried out as the first steps toward the planned experiment are presented.

Paul Langevin the Scientist

“Summarizing Paul Langevin’s work implies revising the whole history of physics (…), this is a difficult but exciting task” Louis de Broglie said during Langevin’s funeral. Paul Langevin was a universal mind, and he had worked in all branches of physics: gaseous ions, Brownian motion, electromagnetism, dia and para magnetism, birefringence, special relativity, ultrasonic waves, and neutron collisions. Very rare are those who can pretend to such a scientific impact. Yet at the same time, during a time span that included two world wars, Paul Langevin directed an engineering school ESPCI (Ecole Supérieure de Physique et Chimie Industrielle), gave courses at collège de France, ENS (Ecole Normale Supérieure), and was actively involved in the Solvay Conferences that he organized when Hendrick Lorentz passed away. The last part of the presentation is devoted to the present Paul Langevin legacy. As illustrations, a membrane wave experiment that revisits the 1919 Eddington observation of Albert Einstein prediction is followed by a walking liquid droplet set-up by Yves Couder. Open questions about the unfinished work that Paul Langevin and his scientific Solvay group left us will conclude this presentation.

Computational investigation of the dynamic response of silicon carbide ceramic under impact loading

It is estimated that by 2027, the global ballistic ceramic composites market would reach a value of US$3.67 billion. Many nations are increasing their military spending in order to better safeguard their military personnel, which has resulted in a tremendous increase in the market. As a result of the growing need for lighter, stronger, and harder ballistics, SiC-based composites are predicted to be the most lucrative of all ceramic materials. The study describes a finite-element model for ceramic carbide based on Johnson and Holmquist’s well-suited constitutive model for ceramics. The dynamic material tests of Strassburger et al [Strassburger, E., H. Senf, and H. Rothenhäusler, 1994 Fracture propagation during impact in three types of ceramics. Le Journal de Physique IV. 4: C8-653-C8-658.] were replicated computationally to develop further insight about the material behavior under impact loading. Materials. were simulated using the elastic properties and Johnson-Holmquist (JH-2) material models, respectively, for metal and ceramic materials. The stress distribution, damage progression, and failure of the material were accurately predicted by the results. The damage pattern, failure type, and method of failure are all examined as a result of altering projectile velocity. Computational data is utilized to verify the model’s accuracy and offer insight into the ceramic’s reaction to high strain.

Desorption of polycyclic aromatic hydrocarbons by cosmic rays

Context. The rate of sputtering and release of condensed species is an important aspect of interstellar chemistry, as is photodesorption for the most volatile species, because in the absence of such mechanisms the whole gas phase would have to condense in times often shorter than the lifetime of the considered medium, in particular for dense clouds. The recent detection of cyclic aromatic molecules by radioastronomy requires an understanding of the potential mechanisms supporting the rather high abundances observed. Aims. We perform experiments to advance our understanding of the sputtering yield due to cosmic rays for very large carbonaceous species in the solid phase. Methods. Thin films of perylene and coronene were deposited on a quartz cell microbalance and exposed to a 1.5 MeV N+ ion beam at the Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab, Orsay, France) and a 230 MeV 48Ca10+ ion beam at the GSI Helmholtzzentrum für Schwerionenforschung (GSI, Darmstadt, Germany). The mass loss was recorded as a function of the fluence for the N+ beam. The microbalance response was calibrated using Fourier transform infrared (FTIR) reflectance measurements of the produced films. In addition, the destruction cross-section of the same species was measured with the 48Ca10+ ion beam by in situ monitoring of the evolution of the infrared spectra of the bombarded films. Results. We deduced the sputtering yield for perylene and coronene and their radiolysis destruction cross-sections. Combining these results with a cosmic ray astrophysical spectrum, we discuss the impact on the possible abundance that may originate from the sputtering of dust grains with these molecules as well as from polycyclic aromatic molecules when they are trapped in ice mantles.

Notes on tensor models and tensor field theories

Tensor models and tensor field theories admit a $1/N$ expansion and a melonic large $N$ limit which is simpler than the planar limit of random matrices and richer than the large $N$ limit of vector models. They provide examples of analytically tractable but non-trivial strongly coupled quantum field theories and lead to a new class of conformal field theories. We present a compact introduction to the topic, covering both some of the classical results in the field, like the details of the $1/N$ expansion, as well as recent developments. These notes are loosely bases on four lectures given at the Journées de physique mathématique Lyon 2019: Random tensors and SYK models.

Robust optimization should be used to replace PTV in radiotherapy treatment planning.

Medical PhysicsEarly View POINT COUNTERPOINT Robust optimization should be used to replace PTV in radiotherapy treatment planning Marie-Claude Biston, Unité de Physique, Centre Léon Bérard, Lyon cedex, FranceSearch for more papers by this authorXiaoying Liang, Radiation Oncology Department, Mayo Clinic, Jacksonville, Florida, USASearch for more papers by this authorZuofeng Li, Corresponding Author zuofeng.li@outlook.com Radiation Oncology Department, Guangzhou Concord Cancer Center, Guangzhou, Guangdong, China Correspondence Zuofeng Li, Radiation Oncology Department, Guangzhou Concord Cancer Center, #9 CIJI Road, Sino-Singapore Knowledge City, Huangpu District, Guangzhou, Guangdong, China. Email: zuofeng.li@outlook.comSearch for more papers by this author Marie-Claude Biston, Unité de Physique, Centre Léon Bérard, Lyon cedex, FranceSearch for more papers by this authorXiaoying Liang, Radiation Oncology Department, Mayo Clinic, Jacksonville, Florida, USASearch for more papers by this authorZuofeng Li, Corresponding Author zuofeng.li@outlook.com Radiation Oncology Department, Guangzhou Concord Cancer Center, Guangzhou, Guangdong, China Correspondence Zuofeng Li, Radiation Oncology Department, Guangzhou Concord Cancer Center, #9 CIJI Road, Sino-Singapore Knowledge City, Huangpu District, Guangzhou, Guangdong, China. Email: zuofeng.li@outlook.comSearch for more papers by this author First published: 23 September 2021 https://doi.org/10.1002/mp.15249Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

Effects of crystallite stacking on adsorption of ethylene on graphitized thermal carbon black

Adsorption of gases on graphitized thermal carbon black (GTCB) is frequently modelled as a homogeneous planar graphite with infinite extent in the directions parallel to the surface. TEM micrographs of GTCB, however, show polyhedral crystallites with a finite basal plane on their faces. The stacking of these crystallites results in wedge shaped spaces in which the interaction energy with an adsorbate is enhanced by overlapping potentials from the graphitic basal planes of adjacent crystallites in the vicinity of their junction. This enhancement facilitates clustering of molecules and the subsequent formation of a condensate, in addition to molecular layering on the basal planes. As a result, contributions to the adsorbed density observed experimentally originate from both molecules on the basal graphitic planes, and those at the junction of the planes. The former is favoured entropically because of the large area of the basal planes, while the latter is favoured energetically. We have tested this new wedge model by comparison with the experimental data of Menaucourt, Thomy and Duval [Le Journal de Physique, 1977, 38, C4-195] for ethylene adsorbed on exfoliated graphite at three temperatures and show that the simulation results describe the data better than those based on a homogeneous planar graphite model.

Effects of the chromospheric Lyα line profile shape on the determination of the solar wind H I outflow velocity using the Doppler dimming technique

Context. The determination of solar wind H I outflow velocity is fundamental to shedding light on the mechanisms of wind acceleration occurring in the corona. Moreover, it has implications in various astrophysical contexts, such as in the heliosphere and in cometary and planetary atmospheres. Aims. We aim to study the effects of the chromospheric Lyα line profile shape on the determination of the outflow speed of coronal H I atoms via the Doppler dimming technique. This is of particular interest in view of the upcoming measurements of the Metis coronagraph aboard the Solar Orbiter mission. Methods. The Doppler dimming technique exploits the decrease of coronal Lyα radiation in regions where H I atoms flow out in the solar wind. Starting from UV observations of the coronal Lyα line from the Solar and Heliospheric Observatory (SOHO), aboard the UltraViolet Coronagraph Spectrometer, and simultaneous measurements of coronal electron densities from pB coronagraphic observations, we explored the effect of the profile of the pumping chromospheric Lyα line. We used measurements from the Solar UV Measurement of Emitted Radiation, aboard SOHO, the Ultraviolet Spectrometer and Polarimeter, aboard the Solar Maximum Mission, and the Laboratoire de Physique Stellaire et Planetaire, aboard the Eight Orbiting Solar Observatory, both from representative on-disc regions, such as coronal holes and quiet Sun and active regions, and as a function of time during the solar activity cycle. In particular, we considered the effect of four chromospheric line parameters: line width, reversal depth, asymmetry, and distance of the peaks. Results. We find that the range of variability of the four line parameters is of about 50% for the width, 69% for the reversal depth, and 35% and 50% for the asymmetry and distance of the peaks, respectively. We then find that the variability of the pumping Lyα profile affects the estimates of the coronal H I velocity by about 9−12%. This uncertainty is smaller than the uncertainties due to variations of other physical quantities, such as electron density, electron temperature, H I temperature, and integrated chromospheric Lyα radiance. Conclusions. Our work suggests that the observed variations in the chromospheric Lyα line profile parameters along a cycle and in specific regions negligibly affect the determination of the solar wind speed of H I atoms. Due to this weak dependence, a unique shape of the Lyα profile over the solar disc that is constant in time can be adopted to obtain the values of the solar wind H I outflow velocity. Moreover, the use of an empirical analytical chromospheric profile of the Lyα, assumed uniform over the solar disc and constant in time, is justifiable in order to obtain a good estimate of the coronal wind H I outflow velocity using coronagraphic UV images.

Ernest Rutherford’s ambitions

One of the pioneers of radioactivity research, Rutherford feared his work would be overlooked—and changed his publishing strategies to make sure it wasn’t.

Building a Natural-Hazard-Resilient High-Quality Seismic Network: How WI Network Sustained Hurricanes Maria and Irma

Abstract Between 2008 and 2014, the Institut de Physique du Globe de Paris (IPGP) and the University of the West Indies, Seismic Research Centre (UWI-SRC) designed and built a regional seismic network across the Lesser Antilles. One of the goals of the network is to provide real-time seismic data to the tsunami warning centers in the framework of the Intergovernmental Coordination Group working toward the establishment of a tsunami and other coastal hazards early warning system (ICG-CARIBE-EWS) for the Caribbean and adjacent regions (McNamara et al., 2016). In an area prone to hurricanes, earthquakes, tsunamis, and volcanic eruptions, we chose different techniques and technologies to ensure that our cooperated network could survive and keep providing data in case of major natural hazards. The Nanometrics very small aperture terminal (VSAT) technology is at the heart of the system. It allows for duplicated data collection at the three observatories (Trinidad, Martinique, and Guadeloupe; Anglade et al., 2015). In 2017, the network design and implementation were put to the test with Saffir–Simpson category 5 hurricanes Irma and Maria that went, respectively, through the north and central portion of the Lesser Antilles, mainly impacting the sites operated by volcanological and seismological observatories of IPGP in Martinique (Observatoire Volcanologique et Sismologique de Martinique [OVSM]) and in Guadeloupe (Observatoire Volcanologique et Sismologique de Guadeloupe [OVSG]). Our concepts proved to be valid with a major data shortage of less than 12 hr and only two stations having sustained heavy damage. In this article, we review the strengths and weaknesses of the initial design and discuss various steps that can be taken to enhance the ability of our cooperated network to provide timely real-time seismic data to tsunami warning centers under any circumstances.

The ThomX ICS source

ThomX is a new generation Compact Compton Source. It is currently commissioned by and at the IJCLab (Laboratoire de physique des 2 infinis - Irène Joliot-Curie (UMR9012)) at Orsay. The first beam is expected at the begining of 2021. The aim of ThomX is to demonstrate the characteristics of an intense and Compact (lab-size) X-ray source based on Compton Scattering. The performances are mostly driven by the laser optical system which is above the state of the art of stored laser power. Proof of principle of various X-ray techniques will be performed thanks to the versatile ThomX beamline. Firstly, this article presents the machine description. Secondly, the issues and limits of the laser system are discussed. Then, the ThomX beamline is described and the machine status conclude the ThomX presentation. Finally, the expected performances for the next years and the possible experiments that can be made with this new machine are detailed.