Amélioration des performances d'un avon régional par l'utilisation de riblets et de la technologie NLF

International audienceThe application of riblets on a typical regional turboprop configuration is discussed in this paper. The effect of the riblets is modeled as a singular roughness problem by a proper boundary condition at the wall. The model, already proposed in a previous paper, is briefly described. The drag prediction capabilities are verified by showing some airfoil flow applications. Then a typical wing-body of a regional aircraft is considered. The configuration has been designed to have extended natural laminar flow in cruise conditions. Riblets are applied at flow specifications representative of cruise in combination with the natural laminar flow technology and in climb/descent conditions. A comparison of the two technologies in terms of drag reduction is presented. Their combined application can result in a cruise drag reduction of more than 20%. The resulting fuel savings during a typical operational day are evaluated

Measurements of Aerosol Size and Microphysical Properties: A Comparison Between Raman Lidar and Airborne Sensors

This manuscript compares measurements of aerosol size distributions and microphysical properties retrieved from the Raman lidar BASIL with those obtained from a series of aircraft sensors during HyMeX-SOP1. The attention is focused on a measurement session on 02 October 2012, with BASIL measurements revealing the presence of a lower aerosol layer extending up to 3.3 km and an elevated layer extending from 3.6 to 4.6 km. Aerosol size distribution and microphysical properties are determined from multi-wavelength particle backscattering and extinction profile measurements through a retrieval approach based on Tikhonov regularization. A good agreement is found between BASIL and the microphysical sensors' measurements for all considered aerosol size and microphysical properties. Specifically, BASIL and in-situ volume concentration values are in the range 2-5 mu m(3) cm(-3) in the lower layer and in the range 1-3.5 mu m(3) cm(-3) in the upper layer. Values of the effective radius values from BASIL and the in-situ sensors are in the range 0.2-0.6 mu m in both the lower and upper layer. Aerosol size distributions are determined at 2.2, 2.8, 4 and 4.3 km, with a good agreement between the Raman lidar and the microphysical sensors at all considered heights. We combined these size and microphysical results with Lagrangian back-trajectory analyses and chemical composition measurements. From this combination of datasets we conclude that aerosol particles below 3 km were probably originated by wildfires in North America and/or by anthropogenic activities in North-Eastern Europe, while aerosols above 3 km were also probably originated by wildfires in North America

Clear-air lidar dark band

Abstract. This paper illustrates measurements carried out by the Raman lidar BASIL in the frame of the HD(CP)2 Observational Prototype Experiment (HOPE), revealing the presence of a clear-air dark band phenomenon (i.e. a minimum in lidar backscatter echoes) in the upper portion of the convective boundary layer. The phenomenon is clearly distinguishable in the lidar backscatter echoes at 532 and 1064 nm, as well as in the particle depolarisation data. This phenomenon is attributed to the presence of lignite aerosol particles advected from the surrounding open pit mines in the vicinity of the measuring site. The paper provides evidence of the phenomenon and illustrates possible interpretations for its occurrence

Characterisation of boundary layer turbulent processes by the Raman lidar BASIL in the frame of HD(CP) 2 Observational Prototype Experiment

Abstract. Measurements carried out by the University of Basilicata Raman lidar system (BASIL) are reported to demonstrate the capability of this instrument to characterise turbulent processes within the convective boundary layer (CBL). In order to resolve the vertical profiles of turbulent variables, high-resolution water vapour and temperature measurements, with a temporal resolution of 10 s and vertical resolutions of 90 and 30 m, respectively, are considered. Measurements of higher-order moments of the turbulent fluctuations of water vapour mixing ratio and temperature are obtained based on the application of autocovariance analyses to the water vapour mixing ratio and temperature time series. The algorithms are applied to a case study (11:30–13:30 UTC, 20 April 2013) from the High Definition Clouds and Precipitation for Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE), held in western Germany in the spring 2013. A new correction scheme for the removal of the elastic signal crosstalk into the low quantum number rotational Raman signal is applied. The noise errors are small enough to derive up to fourth-order moments for both water vapour mixing ratio and temperature fluctuations.To the best of our knowledge, BASIL is the first Raman lidar with a demonstrated capability to simultaneously retrieve daytime profiles of water vapour turbulent fluctuations up to the fourth order throughout the atmospheric CBL. This is combined with the capability of measuring daytime profiles of temperature fluctuations up to the fourth order. These measurements, in combination with measurements from other lidar and in situ systems, are important for verifying and possibly improving turbulence and convection parameterisation in weather and climate models at different scales down to the grey zone (grid increment  ∼  1 km; Wulfmeyer et al., 2016).For the considered case study, which represents a well-mixed and quasi-stationary CBL, the mean boundary layer height is found to be 1290 ± 75 m above ground level (a.g.l.). Values of the integral scale for water vapour and temperature fluctuations at the top of the CBL are in the range of 70–125 and 75–225 s, respectively; these values are much larger than the temporal resolution of the measurements (10 s), which testifies that the temporal resolution considered for the measurements is sufficiently high to resolve turbulent processes down to the inertial subrange and, consequently, to resolve the major part of the turbulent fluctuations. Peak values of all moments are found in the interfacial layer in the proximity of the top of the CBL. Specifically, water vapour and temperature second-order moments (variance) have maximum values of 0.29 g2 kg−2 and 0.26 K2; water vapour and temperature third-order moments have peak values of 0.156 g3 kg−3 and −0.067 K3, while water vapour and temperature fourth-order moments have maximum values of 0.28 g4 kg−4 and 0.24 K4. Water vapour and temperature kurtosis have values of  ∼  3 in the upper portion of the CBL, which indicate normally distributed humidity and temperature fluctuations. Reported values of the higher-order moments are in good agreement with previous measurements at different locations, thus providing confidence in the possibility of using these measurements for turbulence parameterisation in weather and climate models.In the determination of the temperature profiles, particular care was dedicated to minimise potential effects associated with elastic signal crosstalk on the rotational Raman signals. For this purpose, a specific algorithm was defined and tested to identify and remove the elastic signal crosstalk and to assess the residual systematic uncertainty affecting temperature measurements after correction. The application of this approach confirms that, for the present Raman lidar system, the crosstalk factor remains constant with time; consequently an appropriate assessment of its constant value allows for a complete removal of the leaking elastic signal from the rotational Raman lidar signals at any time (with a residual error on temperature measurements after correction not exceeding 0.18 K)

Liver involvement and mortality in COVID-19: A retrospective analysis from the CORACLE study group

INTRODUCTION: liver abnormalities are common in COVID-19 patients and associated with higher morbidity and mortality. We aimed to investigate clinical significance and effect on the mortality of abnormal liver function tests (ALFTs) in COVID-19 patients. METHODS: we retrospectively evaluated in a multicentre study all patients admitted with confirmed diagnosis of COVID-19. RESULTS: 434 patients were included in this analysis. Among overall patients, 311 (71.6%) had normal baseline ALT levels. 123 patients showed overall abnormal liver function tests (ALFTs) at baseline [101 ALFTs <2x UNL and 22 ≥2 UNL]. Overall in-hospital mortality was 14% and mean duration of hospitalization was 10.5 days. Hypertension (50.5%), cardiovascular diseases (39.6%), diabetes (23%) were frequent comorbidities and 53.7% of patients had ARDS. At multivariate analysis, the presence of ARDS at baseline (OR=6.11; 95% CI: 3.03–12.32; p<0.000); cardiovascular diseases (OR=4; 95% CI: 2.05–7.81; p<0.000); dementia (OR=3.93; 95%CI:1.87–8.26; p<0.000) and no smoking (OR=4.6; 95% CI: 1.45–14.61; p=0.010) resulted significantly predictive of in-hospital mortality. The presence of ALFTs at baseline was not significantly associated with mortality (OR=3.44; 95% CI=0.81–14.58; p=0.094). CONCLUSION: ALFTs was frequently observed in COVID-19 patients, but the overall in-hospital mortality was mainly determined by the severity of illness, comorbidities and presence of ARDS

Squamous cell carcinoma of the lower lip: FAS/FASL expression, lymphocyte subtypes and outcome.

Squamous cell carcinoma (SCC) of the lip is a relatively common malignancy of the head and neck region. Tumour thickness, grading and perineural invasion are significant prognostic indicators. However, there is still the need of new reliable biological markers able to predict the prognosis of the single cases with an unfavourable biological behaviour unpredictable by the classic clinical-pathological parameters. 32 cases of (SCC) of the lower lip were analysed for their clinicopathologic features, and immunohistochemical expression of Fas/FasL in neoplastic cells and in inflammatory infiltrate. Moreover the density and phenotype of tumour-infiltrating lymphocytes (TIL) were analysed. The results were related with the follow-up of the patients ranging from 2 to 6 years. The cases with over-expression of Fas/FasL in neoplastic cells and Fas+ in T cells preferentially showed a more aggressive clinical behaviour (p<0.01). Moreover we found an alteration of the normal expression of CD4 and CD8 lymphocyte types in ten cases. This data suggest that the Fas/FasL pathway is involved in the close relation between neoplastic cells and T cells and so in the biological behaviour of these tumours