Apport de la mesure de pente de fil au classement mécanique des bois de structures

Si la plupart des machines de classement mécanique des bois de structures se basent sur le module élastique et la densité des planches, peu sont capables de prendre en compte leurs singularités locales. Le Knot Area Ratio, cependant, permet d'améliorer le classement mécanique en considérant la distribution des n uds au sein du bois. A travers cette étude, nous avons pu évaluer l'influence de la pente de fil locale, mesurée grâce à un scanner optique, dans la qualité de la prédiction du module élastique et de la contrainte de rupture des sciages

Improving strength grading of lumber by grain angle measurement and mechanical modeling

Timber strength grading has become a major issue in the European Union during the last years, due to the introduction of the Eurocode 5 and all its related standards. Currently, the most performing strength grading machines are able to locally detect the boards’ knots sizes and positions and interpret this information through adapted grading models. The best lead to improve their accuracy seems to be the introduction of new information about the boards and adapt the mechanical model to take them in account. Small grain angle causes high reduction of clear wood’s mechanical properties, local value of slope of grain appears to be of high interest. The aim of this study is to quantify the additionalaccuracy that grain angle information can bring toan optical scanner used as a strength grading machine. A specific grading model has been developed accordingly, and the results obtained for different machine / model / loading combinations are presented. These results show that slope of grain measurement can significantly improve the accuracy of the optical scanner, for both MOE and MOR estimations.ANR ClaMe

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

Modélisation du comportement mécanique des bois de structures par densitométrie X et imagerie laser

Since the introduction of the Eurocode 5 and its related standards, lumber strength grading has become a major issue for the European wood industry. The main objective and technological limitation of this grading type stands in the estimation of the boards’ mechanical properties, especially their elasticity modulus (MOE) and strength (MOR). The machines currently considered as the most effective are able to locally detect the boards’ knots positions and geometries, and to interpret this data through adapted models. However, these models barely adapt to various stresses distributions, and are not able to take in account other kinds of singularities. Slope of grain around knots, especially, considerably decrease sound wood’s mechanical properties, but its influence on full-size boards had never been quantified. Through this study, we developed an original behavior model, called “Equivalent Profile”, allowing taking in account both stresses distribution and any kind of singularity. We have thus evaluated this model’s performances, considering knottiness data obtained by X-Rays densitometry and slope of grain’s acquired by laser imaging, by comparison between estimated and destructively measured mechanical properties values. We showed, on one hand, that our model provides high performances, without taking in account slope of grain, compared to established methods’ ones. On the other hand, slope of grain data actually allows a substantial improvement of mechanical properties’ estimation accuracy.Le classement mécanique des bois de structures est devenu, depuis l’introduction des Eurocodes 5 et de l’ensemble des normes associées, une problématique centrale de la filière bois dans l’Union Européenne. L’objectif général, ainsi que le principal verrou technologique lié à ce type de classement, réside dans l’estimation des propriétés mécaniques des planches, en particulier leur module élastique (MOE) et leur contrainte de rupture (MOR). Les machines actuellement considérées comme les plus performantes sont capables de détecter les positions et géométries des noeuds des sciages, et d’interpréter ces informations au travers de modèles adaptés. En revanche, ces modèles s’adaptent très mal à des répartitions de contraintes variées, et ne permettent pas de prendre en compte d’autres types de singularités. La déviation des fibres autour des noeuds, en particulier, réduit considérablement les propriétés mécaniques du bois sain, mais son influence sur des pièces de bois de grande taille n’avait jamais été quantifiée. Au cours de cette étude, nous avons développé un modèle de comportement original, appelé « Profilé Equivalent », qui permet à la fois de prendre en compte la répartition des contraintes et tous types de singularités. Nous avons donc pu évaluer les performances de ce modèle, en considérant les informations de nodosité obtenues par densitométrie X et celles de pente de fil obtenues par imagerie laser, par comparaison entre les valeurs de propriétés mécaniques estimées et les valeurs correspondantes mesurées par essais destructifs. Nous avons montré d’une part que notre modèle offre de bonnes performances, sans tenir compte de la pente de fil, au regard de celles obtenues par des méthodes établies. D’autre part, l’information de pente de fil permet bien d’améliorer de manière significative la précision de l’estimation des propriétés mécaniques

Transverse isotropic modelling of left-ventricle passive filling: mechanical characterization for epicardial biomaterial manufacturing

International audienceBiomaterials applied to the epicardium have been studied intensively in recent years for different therapeutic purposes. Their mechanical influence on the heart, however, has not been clearly identified. Most biomaterials for epicardial applications are manufactured as membranes or cardiac patches that have isotropic geometry, which is not well suited to myocardial wall motion. Myocardial wall motion during systole and mechanical properties of the LV wall and can serve as a guide for designing and manufacturing biomedical material better adapted to the local epicardial tissue

CMOS platform for atomic-scale device fabrication

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Nanoscale Wet Chemical Engineering of III-V Quantum Dots for Emerging Solar Applications

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Development of nanoscale wet chemical engineering solutions for epitaxial quantum dots based solar applications

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Parkinsonian gait in elderly people: Significance of the threshold value of two and more falls per year.

Objectives: Parkinsonism in the elderly presents a major risk factor for recurrent falls (2 and more falls per year), which is associated with increased morbidity. The main objective was to investigate explanatory variables relating to the risk of being recurrent fallers (RF) in persons with parkinsonian gait.Methods: Seventy-nine among 172 eligible persons were enrolled in this prospective study, the findings of which were analyzed at 12 months. Motor and non-motor features, as well as follow-up interviews to identify falls, loss of ability to walk, fluctuating cognition, traumatic falls, all-cause hospitalizations and deaths were collated and results compared between non RF (zero and one fall per year) and RF. Bayesian model averaging was used to predict the probability of patients being RF from their medical history as well as from cognitive assessment, gait velocity, vision and posture.Results: N=79, 0.58 men, 50% had Parkinson's disease, 14% other neurodegenerative parkinsonian syndrome, 23% vascular parkinsonism and 13% Lewy body disease, 58% were RF. Median age 81.2 years and median MMSE 25/30. A history of falls and of hallucinations, median odds ratio respectively 9.06 (CI 2.34-38.22), 4.21 (CI 1.04-18.67) were associated with the highest odds ratios along with fluctuating cognition and abnormal posture. Two or more falls a year was a relevant threshold to distinguish a population with a high risk of comorbidity.Conclusion: The whole history of falls, hallucinations and fluctuating cognition can be considered predictive of recurrent falls in elderly people with parkinsonian gait and provide a tracking tool for patient management