Optical turbulence simulations at Mt Graham using the Meso-NH mode

The mesoscale model Meso-NH is used to simulate the optical turbulence at Mt Graham (Arizona, USA), site of the Large Binocular Telescope. Measurements of the CN2-profiles obtained with a generalized scidar from 41 nights are used to calibrate and quantify the model's ability to reconstruct the optical turbulence. The measurements are distributed over different periods of the year, permitting us to study the model's performance in different seasons. A statistical analysis of the simulations is performed for all the most important astroclimatic parameters: the CN2-profiles, the seeing {\epsilon}, the isoplanatic angle {\theta}0 and the wavefront coherence time {\tau}0. The model shows a general good ability in reconstructing the morphology of the optical turbulence (the shape of the vertical distribution of CN2) as well as the strength of all the integrated astroclimatic parameters. The relative error (with respect to measurements) of the averaged seeing on the whole atmosphere for the whole sample of 41 nights is within 9.0 %. The median value of the relative error night by night is equal to 18.7 %, so that the model still maintains very good performances. Comparable percentages are observed in partial vertical slabs (free atmosphere and boundary layer) and in different seasons (summer and winter). We prove that the most urgent problem, at present, is to increase the ability of the model in reconstructing very weak and very strong turbulence conditions in the high atmosphere. This mainly affects the model's performances for the isoplanatic angle predictions, for which the median value of the relative error night by night is equal to 35.1 %. No major problems are observed for the other astroclimatic parameters. A variant to the standard calibration method is tested but we find that it does not provide better results, confirming the solid base of the standard method.Comment: 12 pages, 12 figures. The definitive version can be found at: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2010.18097.x/abstrac

Mitochondrial cristae revealed with focused light.

Because of the diffraction resolution barrier, optical microscopes have so far failed in visualizing the mitochondrial cristae, that is, the folds of the inner membrane of this 200 to 400 nm diameter sized tubular organelle. Realizing a ∼30 nm isotropic subdiffraction resolution in isoSTED fluorescence nanoscopy, we have visualized these essential structures in the mitochondria of intact cells. We find a pronounced heterogeneity in the cristae arrangements even within individual mitochondrial tubules

Optical turbulence vertical distribution with standard and high resolution at Mt. Graham

A characterization of the optical turbulence vertical distribution (Cn2 profiles) and all the main integrated astroclimatic parameters derived from the Cn2 and the wind speed profiles above the site of the Large Binocular Telescope (Mt. Graham, Arizona, US) is presented. The statistic includes measurements related to 43 nights done with a Generalized Scidar (GS) used in standard configuration with a vertical resolution Delta(H)~1 km on the whole 20 km and with the new technique (HVR-GS) in the first kilometer. The latter achieves a resolution Delta(H)~20-30 m in this region of the atmosphere. Measurements done in different periods of the year permit us to provide a seasonal variation analysis of the Cn2. A discretized distribution of Cn2 useful for the Ground Layer Adaptive Optics (GLAO) simulations is provided and a specific analysis for the LBT Laser Guide Star system ARGOS (running in GLAO configuration) case is done including the calculation of the 'gray zones' for J, H and K bands. Mt. Graham confirms to be an excellent site with median values of the seeing without dome contribution epsilon = 0.72", the isoplanatic angle theta0 = 2.5" and the wavefront coherence time tau0= 4.8 msec. We find that the optical turbulence vertical distribution decreases in a much sharper way than what has been believed so far in proximity of the ground above astronomical sites. We find that 50% of the whole turbulence develops in the first 80+/-15 m from the ground. We finally prove that the error in the normalization of the scintillation that has been recently put in evidence in the principle of the GS technique, affects these measurements with an absolutely negligible quantity (0.04").Comment: 11 figures. MNRAS, accepte

Rare case of clear cell sarcoma in a young female

Clear Cell Sarcoma of Tendon and Aponeuroses (CCTA), also known as Melanoma of soft tissue is a rare and highly malignant soft tissue neoplasm which mostly occurs in young adults A 26-year-old female presented with pain and thickened soft tissue in the popliteal fossa at the posterior aspect of the left knee. Ultrasonography demonstrated a cystic mass with irregular wall and internal debris representing a complex popliteal cyst. Further work-up with MRI demonstrated a cystic mass lateral to the semimembranosus muscle tendon. Excisional biopsy of the mass was consistent with malignant neoplasm with plasmacytoid features. Immunoperoxidase and cytogenic studies supported the diagnosis for Clear Cell Sarcoma arising from the tendon sheath

Wind speed vertical distribution at Mt. Graham

The characterization of the wind speed vertical distribution V(h) is fundamental for an astronomical site for many different reasons: (1) the wind speed shear contributes to trigger optical turbulence in the whole troposphere, (2) a few of the astroclimatic parameters such as the wavefront coherence time (tau_0) depends directly on V(h), (3) the equivalent velocity V_0, controlling the frequency at which the adaptive optics systems have to run to work properly, depends on the vertical distribution of the wind speed and optical turbulence. Also, a too strong wind speed near the ground can introduce vibrations in the telescope structures. The wind speed at a precise pressure (200 hPa) has frequently been used to retrieve indications concerning the tau_0 and the frequency limits imposed to all instrumentation based on adaptive optics systems, but more recently it has been proved that V_200 (wind speed at 200 hPa) alone is not sufficient to provide exhaustive elements concerning this topic and that the vertical distribution of the wind speed is necessary. In this paper a complete characterization of the vertical distribution of wind speed strength is done above Mt.Graham (Arizona, US), site of the Large Binocular Telescope. We provide a climatological study extended over 10 years using the operational analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF), we prove that this is representative of the wind speed vertical distribution at Mt. Graham with exception of the boundary layer and we prove that a mesoscale model can provide reliable nightly estimates of V(h) above this astronomical site from the ground up to the top of the atmosphere (~ 20 km).Comment: 12 pages, 9 figures (whereof 3 colour), accepted by MNRAS May 27, 201