78 research outputs found
The flow structure behind vortex generators embedded in a decelerating turbulent boundary layer
The objective of the present work is to analyse the behaviour of a turbulent decelerating boundary layer under the effect of both passive and active jets vortex generators (VGs). The stereo PIV database of Godard and Stanislas [1, 2] obtained in an adverse pressure gradient boundary layer is used for this study. After presenting the effect on the mean velocity field and the turbulent kinetic energy, the line of analysis is extended with two points spatial correlations and vortex detection in instantaneous velocity fields. It is shown that the actuators concentrate the boundary layer turbulence in the region of upward motion of the flow, and segregate the near-wall streamwise vortices of the boundary layer based on their vorticity sign
Dynamics of a pre-stalled windturbine blade using control of circulation at the trailing-edge
Wind turbines are installed in the strongly inhomogeneous and unsteady turbulent atmospheric boundary layer. This induces unsteady mechanical loads at different characteristic time scales from seconds to minutes which limit significantly their life time. The present work, supported by the SMARTEOLE ANR project, focuses on the flow control strategies at the blade scale, to manipulate lift and thus alleviate some of these loads. For this purpose, a NACA654-421 airfoil profile has been modified : the trailing edge has been rounded to take advantage of Coanda effects and the camber has been increased to compensate the loss of lift due to the trailing edge modifications. The lift control is obtained by fluidic injection via 42 1x1 mm micro-jets placed at the trailing edge along the entire span of the wing. An experiment has been conducted to identify both static and dynamic performances of the proposed control mechanism. The experimental campaign consisted in chordwise unsteady pressure measurements as well as aerodymics forces measurements. The preliminary results of the mean quantities indicate that the lift gain obtained is proportional to the fluidic injection, which is of interest when closed-loop control is to be considered. In a second series of measurements, we focus on the step-response of the flow to the actuation. The lift response is shown to behave as a first order dynamics and we show that the response time of lift is of the order of 3 convective time units. This is about three times faster than what is usually observed for boundary layer reattachement process
An end is in sight: a perspective on PCR as an endpoint for Chagas disease treatment trials
Novel therapies for chronic indeterminate Chagas disease (CICD) are needed, but trials are limited by the absence of tests to detect infection and early treatment efficacy. This perspective highlights the shortfalls and strengths of polymerase chain reaction (PCR) as a study endpoint for anti-parasitic drug development. Serologic reversion, the gold standard test of cure, may take decades to occur in adults and therefore is challenging as an endpoint for drug development. Use of PCR as a marker of infection and treatment response has notable limitations due to low parasitemia in CICD, fluctuations in circulating (versus tissue) parasite burden, strain differences, and assay performance. It is, however, rapidly responsive to therapy, and technological advances have improved detection of different strains and may allow for parasite quantification. Until we have more sensitive tests for parasitological clearance, PCR as a measure of treatment failure may be the best available efficacy endpoint to accelerate early development of much-needed novel therapies. Adequately designed clinical studies are needed to correlate PCR clearance with clinical outcomes and to identify novel biomarkers predictive of clinical outcomes in patients with CICD. Public-private partnerships and health authority engagement are paramount to identify feasible trial endpoints and deliver promising new drug candidates for Chagas disease
Pimasertib Versus Dacarbazine in Patients With UnresectableNRAS-Mutated Cutaneous Melanoma: Phase II, Randomized, Controlled Trial with Crossover
This study investigated the efficacy and safety of pimasertib (MEK1/MEK2 inhibitor) versus
dacarbazine (DTIC) in patients with untreated NRAS-mutated melanoma. Phase II, multicenter, open-label trial. Patients with unresectable, stage IIIc/IVM1 NRAS-mutated cutaneous melanoma were
randomized 2:1 to pimasertib (60 mg; oral twice-daily) or DTIC (1000 mg/m2
; intravenously) on Day 1
of each 21-day cycle. Patients progressing on DTIC could crossover to pimasertib. Primary endpoint:
investigator-assessed progression-free survival (PFS); secondary endpoints: overall survival (OS),
objective response rate (ORR), quality of life (QoL), and safety. Overall, 194 patients were randomized
(pimasertib n = 130, DTIC n = 64), and 191 received treatment (pimasertib n = 130, DTIC n = 61).
PFS was significantly improved with pimasertib versus DTIC (median 13 versus 7 weeks, respectively;
hazard ratio (HR) 0.59, 95% confidence interval (CI) 0.42–0.83; p = 0.0022). ORR was improved with
pimasertib (odds ratio 2.24, 95% CI 1.00–4.98; p = 0.0453). OS was similar between treatments (median
9 versus 11 months, respectively; HR 0.89, 95% CI 0.61–1.30); 64% of patients receiving DTIC crossed
over to pimasertib. Serious adverse events (AEs) were more frequent for pimasertib (57%) than
DTIC (20%). The most common treatment-emergent AEs were diarrhea (82%) and blood creatine
phosphokinase (CPK) increase (68%) for pimasertib, and nausea (41%) and fatigue (38%) for DTIC.
Most frequent grade ≥3 AEs were CPK increase (34%) for pimasertib and neutropenia (15%) for DTIC.
Mean QoL scores (baseline and last assessment) were similar between treatments. Pimasertib has
activity in NRAS-mutated cutaneous melanoma and a safety profile consistent with known toxicities
of MEK inhibitors. Trial registration: ClinicalTrials.gov, NCT01693068
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