45 research outputs found

    The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

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    The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submillimetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25 pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64 pixels, respectively, to perform integral-field spectroscopy and imaging photometry in the 60-210\mu\ m wavelength regime. In photometry mode, it simultaneously images two bands, 60-85\mu\ m or 85-125\mu\m and 125-210\mu\ m, over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling in each band. In spectroscopy mode, it images a field of 47"x47", resolved into 5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectral resolution of ~175km/s. We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the Performance Verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions

    Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius

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    We report the discovery of very shallow (DF/F = 3.4 10-4), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which we interpret as due to the presence of a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion. Methods. We use CoRoT color information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy and preliminary results from Radial Velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star are derived from optical spectra, which were then combined with the CoRoT light curve to derive parameters of the companion. We examine carefully all conceivable cases of false positives, and all tests performed support the planetary hypothesis. Blends with separation larger than 0.40 arcsec or triple systems are almost excluded with a 8 10-4 risk left. We conclude that, as far as we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 59 +/- 3 10-5 day and a radius of Rp = 1.68 +/- 0.09 REarth. Analysis of preliminary radial velocity data yields an upper limit of 21 MEarth for the companion mass, supporting the finding. CoRoT-7b is very likely the first Super-Earth with a measured radius.Comment: Accepted in Astronomy and Astrophysics; typos and language corrections; version sent to the printer w few upgrade

    NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2—design, manufacturing, and testing of the ultraviolet and visible channel

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    NOMAD is a spectrometer suite on board the ESA/Roscosmos ExoMars Trace Gas Orbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultraviolet and visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadir measurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultraviolet and visible spectrometer channel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometer using a selector mechanism

    Expected Performances of the NOMAD/ExoMars instrument

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    NOMAD (Nadir and Occultation for MArs Discovery) is one of the four instruments on board the ExoMars Trace Gas Orbiter, scheduled for launch in March 2016. It consists of a suite of three high-resolution spectrometers – SO (Solar Occultation), LNO (Limb, Nadir and Occultation) and UVIS (Ultraviolet and Visible Spectrometer). Based upon the characteristics of the channels and the values of Signal-to-Noise Ratio obtained from radiometric models discussed in [Vandaele et al., Optics Express, 2015] and [Thomas et al., Optics Express, 2015], the expected performances of the instrument in terms of sensitivity to detection have been investigated. The analysis led to the determination of detection limits for 18 molecules, namely CO, H2O, HDO, C2H2, C2H4, C2H6, H2CO, CH4, SO2, H2S, HCl, HCN, HO2, NH3, N2O, NO2, OCS, O3. NOMAD should have the ability to measure methane concentrations <25 parts per trillion (ppt) in solar occultation mode, and 11 parts per billion in nadir mode. Occultation detections as low as 10 ppt could be made if spectra are averaged [Drummond et al., Planetary Space and Science, 2011]. Results have been obtained for all three channels in nadir and in solar occultation

    Transiting exoplanets from the CoRoT space mission. VIII. CoRoT-7b: the first super-Earth with measured radius

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    Copyright © The European Southern Observatory (ESO)Aims. We report the discovery of very shallow (ΔF/F ≈ 3.4×10−4), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which we interpret as caused by a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion. Methods. We used CoRoT colours information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy, and preliminary results from radial velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star were derived from optical spectra, which were then combined with the CoRoT light curve to derive parameters of the companion. Results. We examined all conceivable cases of false positives carefully, and all the tests support the planetary hypothesis. Blends with separation >0.40'' or triple systems are almost excluded with a 8 × 10−4 risk left. We conclude that, inasmuch we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 59 ± 3 × 10−5 day and a radius of Rp = 1.68 ± 0.09 REarth. Analysis of preliminary radial velocity data yields an upper limit of 21 MEarth for the companion mass, supporting the finding. Conclusions. CoRoT-7b is very likely the first Super-Earth with a measured radius. This object illustrates what will probably become a common situation with missions such as Kepler, namely the need to establish the planetary origin of transits in the absence of a firm radial velocity detection and mass measurement. The composition of CoRoT-7b remains loosely constrained without a precise mass. A very high surface temperature on its irradiated face, ≈1800–2600 K at the substellar point, and a very low one, ≈50 K, on its dark face assuming no atmosphere, have been derived

    Optical and radiometric models of the NOMAD instrument part II: The infrared channels - SO and LNO

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    Limites de l'étude des potentiels évoqués auditifs précoces dans le diagnostic de la surdité de l'enfant.

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    The author presents the results of his experience concerning brain stem evoked response in children. 122 cases are put forth. It shows that although behavioral audiometry is impossible in 7% of the cases, the BERA (Brain stem Evoked Response Audiology) is not reliable in 26.5% of the treble frequencies and 36% of the bass frequencies. Thus, it is not possible to equip children with hearing aids based on this given alone

    Design-of-experiment strategy for the formulation of laccase biocatalysts and their application to degrade bisphenol A

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    Immobilizing enzymes can expand their applicability to continuous process operations and facilitates process intensification. An optimized formulation of immobilized biocatalysts is therefore of strategic interest in the field of industrial biotechnology. Nevertheless, biocatalyst formulation still largely relies on empirical approaches which lack effectiveness in the identification of optimum immobilization conditions. In the present study, design of experiments, multiple linear regressions and modeling were used to screen, interpret and finally optimize crucial immobilization parameters. A laccase preparation from Coriolopsis polyzona MUCL38443 was immobilized via a sequential adsorption-crosslinking process on mesoporous silica particles. As a target variable, biocatalyst activity was doubled (∼280 Ug -1) while dramatically reducing processing time (two hours instead of 26 hours) and reagent inputs (80 mM instead of 1 M glutaraldehyde (GLU)). Immobilization yield (∼50%) and thermostability (∼60% residual activity after 24 hours at 45°C) could be maintained under the optimized conditions. As an example of its application in environmental biotechnology, the optimized biocatalyst was implemented in a continuous stirred-tank membrane reactor (CSTMR) to continuously degrade the endocrine disruptor bisphenol A (BPA) in wastewater. A 90% removal of 50 μM BPA was achieved over 30 reactor volumes (hydraulic residence time (HRT) of 1.85 hours, 50 mL working volume). © 2012 Elsevier B.V

    Autologous costochondral cartilage implant in two cases of velopharyngeal insufficiency

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    The velopharyngeal sphincter is critical in enabling the functions of speaking and swallowing. Velopharyngeal insufficiency (VPI) results in hypernasal speech and nasal regurgitation. A frequent cause of VPI is congenital cleft palate, but otolaryngologists sometimes encounter iatrogenic VPI after surgery. Treatment of VPI with prostheses is often successful but not always well tolerated. Many surgical procedures have been proposed to correct palatal length or to enlarge the posterior pharyngeal wall. We report two cases in which autologous costochondral cartilage was used as implant augmentation. This approach is indicated and efficient when the velopharyngeal deficit is less than 5 rum. An autologous costochondral cartilage implant procedure is safe and reversible and can be expected to incite minimal host reaction
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