Counter-Rotating Open Rotor (CROR) : flow physics and simulation

La propulsion par hélices contrarotatives est à l'étude dans le contexte des recherches menées sur la réduction de la consommation et du bruit aéronautiques. Dans un Open Rotor, on cherche notamment à maîtriser la nappe tourbillonnaire issue de l'hélice amont car elle vient impacter l'hélice aval, contribuant majoritairement au bruit rayonné. Des simulations avancées de ce problème seront présentées et discutées sur le plan de la mécanique des fluides et de l'acoustique

Conditions critiques de déclenchement du lâcher tourbillonnaire au cours du vol des insectes

Dans le cadre de l'étude du lâcher tourbillonnaire caractéristique du vol des insectes, on procède dans ce travail à une analyse de stabilité globale 2D permettant de déterminer en fonction de l’incidence le nombre de Reynolds critique déclenchant le lâcher tourbillonnaire derrière un profil d'aile statique. Ces résultats théoriques 2D sont ensuite validés en tunnel hydrodynamique et l’étude d’ailes d’allongement fini permet enfin de préciser les effets 3D sur les conditions critiques

Non-contrast CT markers of intracerebral hematoma expansion : a reliability study

Objectives: We evaluated whether clinicians agree in the detection of non-contrast CT markers of intracerebral hemorrhage (ICH) expansion. Methods: From our local dataset, we randomly sampled 60 patients diagnosed with spontaneous ICH. Fifteen physicians and trainees (Stroke Neurology, Interventional and Diagnostic Neuroradiology) were trained to identify six density (Barras density, black hole, blend, hypodensity, fluid level, swirl) and three shape (Barras shape, island, satellite) expansion markers, using standardized definitions. Thirteen raters performed a second assessment. Inter and intra-rater agreement were measured using Gwet’s AC1, with a coefficient > 0.60 indicating substantial to almost perfect agreement. Results: Almost perfect inter-rater agreement was observed for the swirl (0.85, 95% CI: 0.78-0.90) and fluid level (0.84, 95% CI: 0.76-0.90) markers, while the hypodensity (0.67, 95% CI: 0.56-0.76) and blend (0.62, 95% CI: 0.51-0.71) markers showed substantial agreement. Inter-rater agreement was otherwise moderate, and comparable between density and shape markers. Inter-rater agreement was lower for the three markers that require the rater to identify one specific axial slice (Barras density, Barras shape, island: 0.46, 95% CI: 0.40-0.52 versus others: 0.60, 95% CI: 0.56-0.63). Inter-observer agreement did not differ when stratified for raters’ experience, hematoma location, volume or anticoagulation status. Intrarater agreement was substantial to almost perfect for all but the black hole marker. Conclusion: In a large sample of raters with different backgrounds and expertise levels, only four of nine non-contrast CT markers of ICH expansion showed substantial to almost perfect inter-rater agreement

Acute carotid stenting in patients undergoing thrombectomy : a systematic review and meta-analysis

Background The benefit of acute carotid stenting compared with no acute stenting on clinical outcomes among patients with tandem lesions (TL) undergoing endovascular thrombectomy (EVT) remains unknown. Methods We conducted a a systematic review and meta-analysis of studies comparing acute carotid stenting versus no stenting among TL patients undergoing EVT with regards to 90 day modified Rankin Scale (mRS) score, symptomatic intracerebral hemorrhage (sICH), and mortality. Four reviewers screened citations for eligibility and two assessed retained studies for risk of bias and data extraction. A random effects model was used for the synthesis of aggregated data. Results 21 studies (n=1635 patients) were identified for the systematic review; 19 were cohort studies, 1 was a post-hoc analysis of an EVT trial, and 1 was a pilot randomized controlled trial. 16 studies were included in the meta-analysis. Acute stenting was associated with a favorable 90 day mRS score: OR 1.43 (95% CI 1.07, 1.91). No significant heterogeneity between studies was found for this outcome (I2=17.0%; χ2=18.07, p=0.26). There were no statistically significant differences for 3 month mortality (OR 0.80 (95% CI 0.50, 1.28)) or sICH (OR 1.41 (95% CI 0.91, 2.19)). Conclusions This meta-analysis suggests that among TL patients undergoing EVT, acute carotid stenting is associated with a greater likelihood of favorable outcome at 90 days compared with no stenting

Added value of 18F-florbetaben amyloid PET in the diagnostic workup of most complex patients with dementia in France: A naturalistic study

International audienceIntroductionAlthough some studies have previously addressed the clinical impact of amyloid positron emission tomography (PET), none has specifically addressed its selective and hierarchical implementation in relation to cerebrospinal fluid analysis in a naturalistic setting.MethodsThis multicenter study was performed at French tertiary memory clinics in patients presenting with most complex clinical situations (i.e., early-onset, atypical clinical profiles, suspected mixed etiological conditions, unexpected rate of progression), for whom cerebrospinal fluid analysis was indicated but either not feasible or considered as noncontributory (ClinicalTrials.gov: NCT02681172).ResultsTwo hundred five patients were enrolled with evaluable florbetaben PET scans; 64.4% of scans were amyloid positive. PET results led to changed diagnosis and improved confidence in 66.8% and 81.5% of patients, respectively, and altered management in 80.0% of cases.DiscussionHigh-level improvement of diagnostic certainty and management is provided by selective and hierarchical implementation of florbetaben PET into current standard practices for the most complex dementia cases

Cardiopulmonary resuscitation in adults over 80 : outcome and the perception of appropriateness by clinicians

OBJECTIVES: To determine the prevalence of clinician perception of inappropriate cardiopulmonary resuscitation (CPR) regarding the last out‐of‐hospital cardiac arrest (OHCA) encountered in an adult 80 years or older and its relationship to patient outcome. DESIGN: Subanalysis of an international multicenter cross‐sectional survey (REAPPROPRIATE). SETTING: Out‐of‐hospital CPR attempts registered in Europe, Israel, Japan, and the United States in adults 80 years or older. PARTICIPANTS: A total of 611 clinicians of whom 176 (28.8%) were doctors, 123 (20.1%) were nurses, and 312 (51.1%) were emergency medical technicians/paramedics. RESULTS AND MEASUREMENTS: The last CPR attempt among patients 80 years or older was perceived as appropriate by 320 (52.4%) of the clinicians; 178 (29.1%) were uncertain about the appropriateness, and 113 (18.5%) perceived the CPR attempt as inappropriate. The survival to hospital discharge for the “appropriate” subgroup was 8 of 265 (3.0%), 1 of 164 (.6%) in the “uncertain” subgroup, and 2 of 107 (1.9%) in the “inappropriate” subgroup (P = .23); 503 of 564 (89.2%) CPR attempts involved non‐shockable rhythms. CPR attempts in nursing homes accounted for 124 of 590 (21.0%) of the patients and were perceived as appropriate by 44 (35.5%) of the clinicians; 45 (36.3%) were uncertain about the appropriateness; and 35 (28.2%) perceived the CPR attempt as inappropriate. The survival to hospital discharge for the nursing home patients was 0 of 107 (0%); 104 of 111 (93.7%) CPR attempts involved non‐shockable rhythms. Overall, 36 of 543 (6.6%) CPR attempts were undertaken despite a known written do not attempt resuscitation decision; 14 of 36 (38.9%) clinicians considered this appropriate, 9 of 36 (25.0%) were uncertain about its appropriateness, and 13 of 36 (36.1%) considered this inappropriate. CONCLUSION: Our findings show that despite generally poor outcomes for older patients undergoing CPR, many emergency clinicians do not consider these attempts at resuscitation to be inappropriate. A professional and societal debate is urgently needed to ensure that first we do not harm older patients by futile CPR attempts. J Am Geriatr Soc 68:39–45, 201