The Clermont radiometric reference rocks: a convenient tool for dosimetric purposes

soumis à Ancient TLBoreholes drilled in 8 different rocks situated in the vicinity of the Clermont TL laboratory have been used for testing and calibrating methods devoted to measure the natural radioactivity. The present paper gives updated data for the nuclide contents and internal dose-rates for those reference media. Two examples of application are presented. The first example shows dose-rate calibration of a scintillator gamma probe using a threshold method. The second example shows a routine technique for TL dosimetry, based on the rocks for dose-rate reference

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Aberrant thermoluminescence dates obtained from primary volcanic quartz

International audienc

Cells, growth factors and bioactive surface properties in a mechanobiological model of implant healing

International audienceInterface conditions are of prime importance for implant fixation in the early post-operative period and modelling of specific biochemical interactions at implant surface is still missing. We hypothesized that updating osteoblast adhesion properties and growth factor source in an active zone located at the implant surface was relevant to model biochemical interactions of implant with its environment. We proposed an innovative set of diffusive-convective-reactive equations which relevant parameters were the cell decay factor, the cell motility, and the growth factor balance. Initial comparison with histomorphometic results from a stable PMMA canine implant model provided an encouraging base to implement a numerical sensitivity analysis to evaluate the role of three types of bioactive surfaces: acid-etched titanium, coarse grit blasted acid-etched titanium and coarse grit blasted acid-etched titanium with RGDS peptide. We found that cell diffusion decrease (acid-etched + RGDS peptide vs. PMMA), and increase of local growth factor fraction (PMMA vs. acid-etched + RGDS peptide), significantly improved the amount of mineralized tissue on the implant surface. When the variation of structural fraction to cell motility and growth factor synthesis was investigated, an envelope pattern with an optimum was obtained but this could be exceeded for strong surface modifications and/or for high growth factor concentrations. The model also confirmed that implant bioactive properties should play a limited role to reduce heterogeneity of new-formed tissue. In conclusion, we suggested that our innovative theoretical approach was relevant to investigate implant fixation and could potentially help in reduction of implant revision

New paleo- and rockmagnetic constraints for the Laschamp event in the Chaîne des Puys

Thermoluminescence, présenté par G. Plenier, pas de proceedingsThe discovery by Bonhommet and Babkine (1967) of almost reverse directions of magnetization recorded by the Laschamp and Olby lava flows triggered a wide interest. This was indeed the first significant observation supporting the existence of a short geomagnetic event referred as a geomagnetic excursion. Subsequent studies established that these flows were 30 and 40 kyrs old (Gillot et al, 1979) in coincidence with a period of low dipole field intensity. Thus these anomalous directions could either be due to the emergence of the non dipole field or represent an aborted field reversal. An opposite view was put forward by Heller and Petersen (1982) who argued that, despite synchronism with the dipole collapse, the reversed magnetization of the flows was actually not relevant to the field but rather caused by self-reversal processes. The most recent study by Chauvin and Roperch was a response to this rock magnetic hypothesis and argued in favour of a geomagnetic origin. During the past twenty years a large number of thermoluminescence (sometimes 14C) dated flows from the Chaîne des Puys provided ages between 30 and 65 ky BP. We used this opportunity to sample many new units in order to clarify the origin of the magnetization and hopefully improve the resolution of the Laschamp event with additional directions and rock magnetic investigations. We sampled 14 flows with ages between 30 and 65 kyrs and measured 203 samples. Alternating field and thermal demagnetizations were performed on twin samples to investigate the stability and the consistency of the components observed. The results obtained so far reveal that only 7 lavas have a stable characteristic component with normal polarity. Surprisingly, no well defined transitional or reverse direction could be isolated. The seven other flows are characterized by very scattered directions which in some cases can be found along a small circle passing across the normal polarity. In many cases the samples exhibit very complex demagnetization behaviour. Thermomagnetic experiments indicate that magnetite dominates the mineralogy of the samples with normal polarity while a titanomagnetite assemblage controls the magnetization of samples that exhibit anomalous components. This correlation between directions and mineralogy is not incompatible with previous observations by Heller and Petersen for the Olby lava flow. We are currently re-investigating the hypothesis of self reversing magnetization by perform-ing measurements at various temperatures in presence of the field as well as repeated acquisitions of partial thermoremanence with various checks on the residual NR

New paleo- and rockmagnetic results from La Chaine des Puys during the Laschamp event : Evidences of mineralogical disturbances

Thermoluminescence, présenté par J.P. Valet, abstracts bookForty years ago Bonhommet and Babkine (in 1967) reported on two lava flows(Laschamp and Olby) and a scoria cone (Laschamp) from the Chaîne des Puys with almost reversed directions of magnetization which were interpreted as the record of a geomagnetic excursion named after the Laschamp village. Due to specific magnetic mineralogy, these rocks were shown to be prone to self-reversals, potentially misrecording the ambient magnetic field during their emplacement. This new discovery raised a controversy regarding the origin of the directions recorded by these lava flows. Many studies were then conducted to determine the age of the event at 40 ka, which coincides with a period of low dipole field intensity and thus a high probability to observe significant departures of the field from the axial dipolar direction. Taking advantage of new Potassium-argon age determinations, we revisited some sites and sampled several new ones in order to clarify the origin of their magnetization and hopefully improve the resolution of the Laschamp event. This study involves thermal and alternating field demagnetization of 257 samples from 20 units, including 12 new localities, and also experiments of magnetic mineralogy (susceptibility as a function of temperature, thermomagnetic curves, IRM acquisition curves and hysteresis parameters determination). The magnetic mineralogy is dominated by primary titanomagnetite with a Curie temperature of 130±60°C (0.

Non-spiked 40Ar and 36Ar quantification using a quadrupole mass spectrometer : a potential for K-Ar geochronology

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National French Survey of Coronavirus Disease (COVID-19) Symptoms in People Aged 70 and Over

International audienceThe objective of this national French survey was to determine the coronavirus disease 2019 (COVID-19) semiology in seniors (n = 353; mean, 84.7 ± 7.0 years). A total of 57.8% of patients exhibited ≤3 symptoms, including thermal dysregulation (83.6%), cough (58.9%), asthenia (52.7%), polypnea (39.9%), and gastrointestinal signs (24.4%). Patients ≥80 years exhibited falls (P = .002) and asthenia (P = .002). Patients with neurocognitive disorders exhibited delirium (P &lt; .001) and altered consciousness (P = .001). Clinical peculiarities of COVID-19 were reported in seniors. Clinical Trials Registration NCT04343781

Le Moustier : un siècle après Peyrony, la reprise des fouilles.

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