Radiation-induced alteration of apatite on the surface of Mars: first in situ observations with SuperCam Raman onboard Perseverance.

Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must understand past and present processes that can alter materials exposed on the surface, affecting space mission data. Here, we analyze the first dataset monitoring the evolution of a known mineral target in situ on the Martian surface, brought there as a SuperCam calibration target onboard the Perseverance rover. We used Raman spectroscopy to monitor the crystalline state of a synthetic apatite sample over the first 950 Martian days (sols) of the Mars2020 mission. We note significant variations in the Raman spectra acquired on this target, specifically a decrease in the relative contribution of the Raman signal to the total signal. These observations are consistent with the results of a UV-irradiation test performed in the laboratory under conditions mimicking ambient Martian conditions. We conclude that the observed evolution reflects an alteration of the material, specifically the creation of electronic defects, due to its exposure to the Martian environment and, in particular, UV irradiation. This ongoing process of alteration of the Martian surface needs to be taken into account for mineralogical space mission data analysis.

Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars.

The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater's sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide-rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.

Homogeneity assessment of the SuperCam calibration targets onboard rover perseverance.

The SuperCam instrument, onboard the Perseverance rover (Mars 2020 mission) is designed to perform remote analysis on the Martian surface employing several spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman (TRR), Time-Resolved Fluorescence (TRF) and Visible and Infrared (VISIR) reflectance. In addition, SuperCam also acquires high-resolution images using a color remote micro-imager (RMI) as well as sounds with its microphone. SuperCam has three main subsystems, the Mast Unit (MU) where the laser for chemical analysis and collection optics are housed, the Body Unit (BU) where the different spectrometers are located inside the rover, and the SuperCam Calibration Target (SCCT) located on the rover's deck to facilitate calibration tests at similar ambient conditions as the analyzed samples. To perform adequate calibrations on Mars, the 22 mineral samples included in the complex SCCT assembly must have a very homogeneous distribution of major and minor elements. The analysis and verification of such homogeneity for the 5-6 replicates of the samples included in the SCCT has been the aim of this work. To verify the physic-chemical homogeneity of the calibration targets, micro Energy Dispersive X-ray Fluorescence (EDXRF) imaging was first used on the whole surface of the targets, then the relative abundances of the detected elements were computed on 20 randomly distributed areas of 100 × 100 µm. For those targets showing a positive Raman response, micro-Raman spectroscopy imaging was performed on the whole surface of the targets at a resolution of 100 × 100 µm. The %RSD values (percent of relative standard deviation of mean values) for the major elements measured with EDXRF were compared with similar values obtained by two independent LIBS set-ups at spot sizes of 300 µm in diameter. The statistical analysis showed which elements were homogeneously distributed in the 22 mineral targets of the SCCT, providing their uncertainty values for further calibration. Moreover, nine of the 22 targets showed a good Raman response and their mineral distributions were also studied. Those targets can be also used for calibration purposes of the Raman part of SuperCam using the wavenumbers of their main Raman bands proposed in this work.

In situ recording of Mars soundscape.

Before the Perseverance rover landing, the acoustic environment of Mars was unknown. Models predicted that: (1) atmospheric turbulence changes at centimetre scales or smaller at the point where molecular viscosity converts kinetic energy into heat1, (2) the speed of sound varies at the surface with frequency2,3 and (3) high-frequency waves are strongly attenuated with distance in CO2 (refs. 2-4). However, theoretical models were uncertain because of a lack of experimental data at low pressure and the difficulty to characterize turbulence or attenuation in a closed environment. Here, using Perseverance microphone recordings, we present the first characterization of the acoustic environment on Mars and pressure fluctuations in the audible range and beyond, from 20 Hz to 50 kHz. We find that atmospheric sounds extend measurements of pressure variations down to 1,000 times smaller scales than ever observed before, showing a dissipative regime extending over five orders of magnitude in energy. Using point sources of sound (Ingenuity rotorcraft, laser-induced sparks), we highlight two distinct values for the speed of sound that are about 10 m s-1 apart below and above 240 Hz, a unique characteristic of low-pressure CO2-dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO2 vibrational relaxation in the audible range. These results establish a ground truth for the modelling of acoustic processes, which is critical for studies in atmospheres such as those of Mars and Venus.

Reasons for failure of total temporomandibular joint replacement: a systematic review and meta-analysis.

The aim of this study was to evaluate the revision rate after total alloplastic temporomandibular joint replacement (TMJR) and determine whether there is a higher risk of revision surgery with stock or custom-fitted prostheses (the two most current TMJR prosthesis types). A systematic review was performed, with a search of PubMed, Google Scholar, and the Cochrane Library in November 2020. Overall, 27 articles were included in this study, describing Biomet and TMJ Concepts prostheses and including postoperative data on complications requiring a return to the operating room. A total of 2247 prostheses were analysed: 1350 stock Biomet prostheses and 897 custom-fitted TMJ Concepts and custom-fitted Biomet prostheses. The global revision rate was 1.19 per 100 prosthesis-years. The most common reason for revision was heterotopic bone formation. Stock prostheses appeared to have a lower risk of revision compared to custom prostheses: rate ratio 0.52 (95% confidence interval 0.33-0.81, P-value 0.003). Regarding causes of revision, the only significant difference between the types of devices was a higher rate of heterotopic bone formation for custom-made prostheses (P = 0.001). The results of this study revealed a low revision rate post TMJR revision, with stock devices even less prone to such risk. Nevertheless, these results can be explained by the fact that custom-made prostheses are more likely to be used for cases in which the anatomy is significantly abnormal or there is a history of multiple joint surgeries, which carry a greater risk of complications and heterotopic bone formation.

Oral sedation in dentistry: evaluation of professional practice of oral hydroxyzine in the University Hospital of Rennes, France.

PURPOSE: Management of a child's anxiety early in their treatment is essential in dentistry. Sedative medications are used to overcome increased anxiety from previous appointments and to promote the cooperation of children during treatment. Hydroxyzine is currently prescribed to young patients as part of the first level of conscious sedation. The main objective was to evaluate the professional practice of oral hydroxyzine, when prescribed for children presenting anxiety during dental treatment procedure performed by students and senior practitioners. METHODS: A retrospective study of dental records and questionnaires was conducted at the Dental Care Centre of the University Hospital of Rennes, France. Parameters related to the prescription of hydroxyzine in children were evaluated as potential predictors of the dental session success, with adjustments on potential confounders. RESULTS: The therapeutic outcome was very encouraging with 78.3% of success during dental sessions under sedation with oral hydroxyzine. Anxiety levels before the dental procedure and the medication compliance of the child were the main predictors of success. On the other hand, lower age (< 6 years old) and longer treatments (such as pulpotomy) worsened the outcome. CONCLUSIONS: Careful analysis of the literature and results of this work showed the safety of hydroxyzine within the maximum dose authorized without adverse effects, compared to other molecules described and commonly used in dentistry. No adverse effects during dental procedure were noted. This allows for minimal sedation with efficiency for the great majority of pediatric treatment. This solution should be the first step in sedation to help practicing clinicians.

SuperCam Calibration Targets: Design and Development.

SuperCam is a highly integrated remote-sensing instrumental suite for NASA's Mars 2020 mission. It consists of a co-aligned combination of Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), Visible and Infrared Spectroscopy (VISIR), together with sound recording (MIC) and high-magnification imaging techniques (RMI). They provide information on the mineralogy, geochemistry and mineral context around the Perseverance Rover. The calibration of this complex suite is a major challenge. Not only does each technique require its own standards or references, their combination also introduces new requirements to obtain optimal scientific output. Elemental composition, molecular vibrational features, fluorescence, morphology and texture provide a full picture of the sample with spectral information that needs to be co-aligned, correlated, and individually calibrated. The resulting hardware includes different kinds of targets, each one covering different needs of the instrument. Standards for imaging calibration, geological samples for mineral identification and chemometric calculations or spectral references to calibrate and evaluate the health of the instrument, are all included in the SuperCam Calibration Target (SCCT). The system also includes a specifically designed assembly in which the samples are mounted. This hardware allows the targets to survive the harsh environmental conditions of the launch, cruise, landing and operation on Mars during the whole mission. Here we summarize the design, development, integration, verification and functional testing of the SCCT. This work includes some key results obtained to verify the scientific outcome of the SuperCam system.

Mars Science Laboratory Observations of Chloride Salts in Gale Crater, Mars.

The Mars Science Laboratory Curiosity rover is traversing a sequence of stratified sedimentary rocks in Gale crater that contain varied eolian, fluviodeltaic, and lake deposits, with phyllosilicates, iron oxides, and sulfate salts. Here, we report the chloride salt distribution along the rover traverse. Chlorine is detected at low levels (<3 wt.%) in soil and rock targets with multiple MSL instruments. Isolated fine-scale observations of high chlorine (up to ≥15 wt.% Cl), detected using the ChemCam instrument, are associated with elevated Na2O and interpreted as halite grains or cements in bedrock. Halite is also interpreted at the margins of veins and in nodular, altered textures. We have not detected halite in obvious evaporitic layers. Instead, its scattered distribution indicates that chlorides emplaced earlier in particular members of the Murray formation were remobilized and reprecipitated by later groundwaters within Murray formation mudstones and in diagenetic veins and nodules.

Association of surgical excision and brachytherapy for the management of keloids.

Many techniques have been described to prevent the appearance and relapse of keloids but most of them have an efficacy lower than 50%. Our objective is to describe our standardized management of keloids by associated surgery and brachytherapy. Surgery-brachytherapy is usually given only when less invasive treatments failed. Both a surgeon and a radiotherapist are involved. Forty-eight hours of hospitalization in a surgery unit are required. The extra-lesional excision is performed and a brachytherapy sheath is placed in the dermis plane. An iridium source with an initial activity of 300 GBq is used to deliver high dose rate brachytherapy. The brachytherapy sessions are held in a lead-shielded room in a radiotherapy unit: the first session at 6 h after surgical excision, while the second and third on the following day. The total dose administered is 18 Gy. A surgical workup is scheduled at 10 days. The patient is followed-up closely by the radiotherapist for an 18-month period. The recurrence rate after 2 years is 8 to 12%. The main complaints are dyschromia, telangiectasia and skin atrophy.

Fluoride: changes in knowledge and prescription habits of paediatricians for 11 years in Brittany, France.

AIMS: To assess via a questionnaire the changes in knowledge and prescription habits for systemic fluoride of physicians at maternal and infant protection centres (MIP) and paediatricians in private practice (PPP) in the Brittany region between 2003 and 2014. METHODS: In both 2003 and 2014, the same seven-question survey was mailed to PPP (110 in 2003 and 101 in 2014) and MIP (61 in 2003 and 71 in 2014). An eighth question was added in 2014 about French guidelines published in 2008 (AFSSAPS guidelines). RESULTS: The overall response rate was significantly higher in 2003 (69.0%) than in 2014 (54.7%). In 2014 systemic fluoride was still considered an effective means of caries prevention (79.8% vs. 98.7% in 2003) and systematic prescription of fluoride supplements was less common (39.4 vs. 87.0% in 2003). When prescribed, systemic fluoride was given after the first 6 months of a child's life in 2014 (79.8%) instead of within the first month of life (73.5%) in 2003. CONCLUSIONS: Paediatricians and MIP physicians in Brittany were significantly less prone to routinely prescribe systemic fluoride in 2014. Certain sources of fluoride were still not well known in 2014. Collaboration and information sharing between dentists and physicians is necessary.

Chemistry, mineralogy, and grain properties at Namib and High dunes, Bagnold dune field, Gale crater, Mars: A synthesis of Curiosity rover observations.

The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine to medium sized (~45-500 µm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nevertheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured Martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by visible/near-infrared spectra that suggest enrichment of olivine. Collectively, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in Martian soils: (1) amorphous components in the sand-sized fraction (represented by Bagnold) that are Si-enriched, hydroxylated alteration products and/or H2O- or OH-bearing impact or volcanic glasses and (2) amorphous components in the fine fraction (<40 µm; represented by Rocknest and other bright soils) that are Fe, S, and Cl enriched with low Si and adsorbed and structural H2O.

Intraosseous anaesthesia in children with 4 % articaine and epinephrine 1:400,000 using computer-assisted systems.

AIM: To assess retrospectively the efficacy of computer-assisted intraosseous anaesthesia (CAIO) in children using an anaesthetic solution with a lower concentration of epinephrine (1:400,000). METHODS: In a retrospective study, CAIO was evaluated in healthy children and adolescents for restorative and endodontic treatments, uncomplicated tooth extractions or scalings using articaine 4 % plus epinephrine 1:400,000. Anaesthesia was performed in children who showed enough compliance (score of 0-3 according to modified behaviour Venham scale). Efficacy, amount of anaesthetic solution as well as need of a complementary injection was assessed. RESULTS: A total of 421 consecutive sessions were performed on 278 patients aged 7.1 ± 2.9 years with 518 teeth involved in the anaesthetic process and analysed process. When teeth to be anaesthetised were considered, the overall success rate was 97.2 %. In most of the cases, only 0.9 mL was needed to achieve anaesthesia. Permanent teeth needed significantly more anaesthetics than primary teeth. Sensitivity of the teeth anaesthetized reappeared in 5.7 % of cases after 30-60 min of treatment. CONCLUSIONS: These results suggest that CAIO with 4 % articaine and epinephrine diluted 1:400,000 can be an alternative to usual infiltration techniques or IO with epinephrine at a higher concentration for most of treatments in primary and permanent teeth. Further studies are needed to evaluate its efficacy in permanent teeth in case of endodontic treatment or extraction.

A cross-over study comparing an online versus a paper 7-day food record: focus on total water intake data and participant's perception of the records.

PURPOSE: To compare (1) fluid, food and nutrient intake obtained with a paper versus an online version of a 7-day food record and (2) user's acceptability of both versions of the food record. METHODS: A cross-over study was carried out in 2010 in France. A total of 246 participants aged 18-60 years reported their food and fluid intake using both versions of the 7-day food record, separated by a 7- to 14-day washout period. To help participants in estimating consumed portions, both versions of the food record were supported by a photographic booklet of standard portions and containers. At the end of the study protocol, participants completed a questionnaire designed to assess the acceptability of the two questionnaires. RESULTS: The reported water intake of fluids was significantly higher with the online version compared with the paper version (respectively 1348 ± 36 and 1219 ± 34 mL/day, p < 0.0001). No difference was found between methods in terms of energy intake and the consumption of most food categories, macro- and micronutrients. Furthermore, 77 % of the participants preferred the online method to the paper version. CONCLUSIONS: Fluid intake, but not food intake, reported with the online 7-day food record was higher in comparison with the paper version. In addition, the online version was preferred by users. In population surveys, the online record is therefore a relevant alternative, and even a preferred alternative in the case of fluid intake, to the paper record.

Computer-assisted intraosseous anaesthesia for molar and incisor hypomineralisation teeth. A preliminary study.

Anesthetizing MIH (Molar and Incisor Hypomineralisation) teeth is one of the major challenges in paediatric dentistry. Computer-assisted IO injection (CAIO) of 4% articaine with 1:200,000 epinephrine (Alphacaine, Septodont) has been shown to be an efficient way to anesthetize teeth in children. The aim of this study was to assess the efficacy of this method with MIH teeth. This preliminary study was performed using the Quick Sleeper system (Dental Hi Tec, Cholet, France) that allows computer-controlled rotation of the needle to penetrate the bone and computer-controlled injection of the anaesthetic solution. Patients (39) of the department of Paediatric Dentistry were included allowing 46 sessions (including 32 mandibular first permanent molars) to be assessed. CAIO showed efficacy in 93.5% (43/46) of cases. Failures (3) were due to impossibility to reach the spongy bone (1) and to achieve anaesthesia (2). This prospective study confirms that CAIO anaesthesia is a promising method to anesthetize teeth with MIH that could therefore be routinely used by trained practitioners.

Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

Soil diversity and hydration as observed by ChemCam at Gale crater, Mars.

The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration.

The petrochemistry of Jake_M: a martian mugearite.

"Jake_M," the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (>15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type typically found at ocean islands and continental rifts. By analogy with these comparable terrestrial rocks, Jake_M could have been produced by extensive fractional crystallization of a primary alkaline or transitional magma at elevated pressure, with or without elevated water contents. The discovery of Jake_M suggests that alkaline magmas may be more abundant on Mars than on Earth and that Curiosity could encounter even more fractionated alkaline rocks (for example, phonolites and trachytes).

Impact of a rehabilitation program on muscular strength and endurance in peripheral arterial occlusive disease patients.

UNLABELLED: Rehabilitation care and physical exercise are known to constitute an effective treatment for chronic peripheral arterial occlusive disease (PAOD) at the intermittent claudication (IC) stage. Improvements in functional capacities and quality of life have been reported in the literature. We decided to assess the effects of hospital-based exercise training on muscle strength and endurance for the ankle plantar and dorsal flexors in this pathology. PATIENTS AND METHODS: This prospective study included 31 subjects with chronic peripheral arterial occlusive disease (PAOD) and IC who followed a 4-week rehabilitation program featuring walking sessions, selective muscle strengthening, general physical exercise and therapeutic patient education. An isokinetic assessment of ankle plantar and dorsal flexors strength was conducted on the first and last days of the program. We also studied the concentric contractions at the angular velocity of 30°/s and 120°/s for muscle strength and at 180°/s for muscle fatigue. We also measured the walking distance for each patient. RESULTS: Walking distance improved by 246%. At baseline, the isokinetic assessment revealed severe muscle weakness (mainly of the plantar flexors). The only isokinetic parameter that improved during the rehabilitation program was the peak torque for plantar flexors at 120°/s. CONCLUSION: All patients presented with severe weakness and fatigability of the ankle plantar and dorsal flexors. Our program dramatically improved walking distance but not muscle strength and endurance.