Absolute calibration method for frequency-modulated continuous wave (FMCW) cloud radars based on corner reflectors

International audienceThis article presents a new Cloud Radar calibration methodology using solid reference reflectors mounted on masts, developed during two field experiments held in 2018 and 2019 at the SIRTA atmospheric observatory, located in Palaiseau, France, in the framework of the ACTRIS-2 research and innovation program.The experimental setup includes 10 cm and 20 cm triangular trihedral targets installed at the top of 10 m and 20 m masts, respectively. The 10 cm target is mounted on a pan-tilt motor at the top of the 10 m mast to precisely align its boresight with the radar beam. Sources of calibration bias and uncertainty are identified and quantified. Specifically, this work assesses the impact of receiver compression, incomplete antenna overlap, temperature variations inside the radar, clutter and experimental setup misalignment. Setup misalignment is a source of bias previously undocumented in the literature, that can have an impact on the order of tenths of dB in calibration retrievals of W band Radars.A detailed analysis enabled the design of a calibration methodology which can reach a cloud radar calibration uncertainty of 0.3 dB based on the equipment used in the experiment. Among different sources of uncertainty, the two largest terms are due to signal-to-clutter ratio and radar-to-target alignment. The analysis revealed that our 20 m mast setup with an approximate alignment approach is preferred to the 10 m mast setup with the motor-driven alignment system. The calibration uncertainty associated with signal-to-clutter ratio of the former is ten times smaller than for the latter.Following the proposed methodology, it is possible to reduce the added contribution from all uncertainty terms, excluding the target characterization, down to 0.4 dB. Therefore, this procedure should enable the achievement of calibration uncertainties under 1 dB when characterized reflectors are available.Cloud radar calibration results are found to be repeatable when comparing results from a total of 18 independent tests. Once calibrated the cloud radar provides valid reflectivity values when sampling mid-tropospheric clouds. Thus we conclude that the method is repeatable and robust, and that the uncertainties are precisely characterized. The method can be implemented under different configurations as long as the proposed principles are respected. It could be extended to reference reflectors held by other lifting devices such as tethered balloons or unmanned aerial vehicles

Medullary thyroid carcinoma: 20 years experience

Background: Medullary thyroid carcinoma (MTC) is a rare malignant tumor that arise from C cells. Surgical treatment and its results are controversial, so we decided to study it. Aim: To describe clinically MTC, treatment and outcomes in the long term. Material and Method: We retrospectively reviewed medical records of patients with MTC operated in our hospital between the years 1987 and 2007. We analyzed the clinical characteristics, treatment, morbidity and long-term follow up. Results: There were 24 patients operated with a mean age of 46.1 ± 16.6 years. The main form of presentation was painless increased cervical volume (56.2%). In 15% this pathology was part of a MEN 2b. All of them have had a total thyroidectomy, which was extended in 50% of cases. The 35.2% were multifocal, 29.4% bilateral and 62.5% had metastatic lymph node involvement. Five patients remained higher calcitonin levels in the postoperative period and 9 patients recurred clinically on average 4.5 years after surgery. The presence of persistent disease was significantly associated with hereditary MTC (p = 0.0088) and the clinical recurrence was significantly determined by the presence of not expanded total thyroidectomy (p = 0.0196). The probability of surviving more than 19 years was 66.6% (95% CI = 0.24 to 0.89). Conclusions: The MTC is a rare tumour and treatment of choice is surgery. The persistent disease is associated with hereditary MTC form, and the clinical recurrence is associated with not expanded total thyroidectomy. We recommend total thyroidectomy with central voiding and radical modified jugular dissection

Fog Analysis during SOFOG3D Experiment

International audienceTransportation especially aviation sector all around the world is severely hindered due to Fog and hence observations and specific research for fog is necessary. The SOFOG3D (SOuth west FOGs 3D) experiment took place in South-West of France which is particularly prone to fog occurrence, during the period between November 2019 to March 2020 with primary objective to advance our understanding of fog processes and to improve fog forecast. Simultaneous measurements from various remote sensing instruments like BASTA: a 95 GHz cloud radar with scanning capability, HATPRO Microwave radiometer (MWR), doppler lidar, and balloon-borne in-situ measurements were collected to characterize the spatio-temporal evolution of Fog. On the supersite, detailed measurements of meteorological conditions, aerosol properties, fog microphysics, water deposition, radiation budget, heat, and momentum fluxes are collected to provide 3D structure of the boundary layer during fog events. The improvement in the retrieval of fog parameters and understanding of fog dynamics based on cloud radar and microwave (MWR) synergy will be addressed. We will present our work on the retrieval of key fog parameters like dynamics and microphysics using a combination of cloud radar and MWR observations. The retrievals will be validated with the tethered-balloon and radio-sounding observations. In-situ measurements and remote-sensing retrievals of fog microphysical properties will be compared. We will show a detailed analysis of retrieved LWP derived from BASTA radar only with LWP derived from HATPRO microwave radiometer, considering instrumental uncertainty and sensitivity. A closer analysis of the in-situ data (measured by granulometer) will be presented in order to assess and improve the retrieval derived with cloud radar in vertically pointing mode. Radar attenuation will be quantified by measuring the backscattered radar signal on well-known calibrated reflectivity metallic targets installed at the top of 20 m mast. The integrated attenuation along the radar beam path will be measured by the cloud radar and used as a new constraint to improve the microphysical properties.</p&gt

Study and management of thyroid nodes by non specialist physicians: SOCHED consensus

The thyroid nodule is a frequent cause of primary care consultation. The prevalence of a palpable thyroid nodule is approximately 4-7%, increasing up to 67% by the incidental detection of nodules on ultrasound. The vast majority are benign and asymptomatic, staying stable over time. The clinical importance of studying a thyroid nodule is to exclude thyroid cancer, which occurs in 5 to 10% of the nodules. The Board of SOCHED (Chilean Society of Endocrinology and Diabetes) asked the Thyroid Study Group to develop a consensus regarding the diagnostic management of the thyroid nodule in Chile, aimed at non-specialist physicians and adapted to the national reality. To this end, a multidisciplinary group of 31 experts was established among university academics, active researchers with publications on the subject and prominent members of scientific societies of endocrinology, head and neck surgery, pathology and radiology. A total of 14 questions were developed with key aspects for the diagnosis and subsequent referral of patients with thyroid nodules, which were addressed by the participants. In those areas where the evidence was insufficient or the national reality had to be considered, the consensus opinion of the experts was used through the Delphi methodology. The consensus was approved by the SOCHED board for publication

Species diversification – which species should we use?

Large detector systems for particle and astroparticle physics; Particle tracking detectors; Gaseous detectors; Calorimeters; Cherenkov detectors; Particle identification methods; Photon detectors for UV. visible and IR photons; Detector alignment and calibration methods; Detector cooling and thermo-stabilization; Detector design and construction technologies and materials. The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems. as established by test beam measurements and simulation studies. is described. © 2008 IOP Publishing Ltd and SISSA