23 research outputs found
Metallization of cyanide-modified Pt(111) electrodes with copper
The support of the University of Aberdeen is gratefully acknowledged. CW acknowledges a summer studentship from the Carnegie Trust for the Universities of Scotland.Peer reviewedPostprin
Super-Nernstian Shifts of Interfacial Proton-Coupled Electron Transfers : Origin and Effect of Noncovalent Interactions
The support of the University of Aberdeen is gratefully acknowledged. C.W. acknowledges a summer studentship from the Carnegie Trust for the Universities of Scotland. E.P.M.L. acknowledges SeCYT (Universidad Nacional de Cordoba), ́ CONICET- PIP 11220110100992, Program BID (PICT 2012-2324), and PME 2006-01581 for financial support.Peer reviewedPostprin
Reconstruction of the gastric passage by a side-to-side gastrogastrostomy after failed vertical-banded gastroplasty: a case report
INTRODUCTION: Vertical-banded gastroplasty, a technique that is commonly performed in the treatment of morbid obesity, represents a nonadjustable restrictive procedure which reduces the volume of the upper stomach by a vertical stapler line. In addition, a textile or silicone band restricts food passage through the stomach. CASE PRESENTATION: A 71-year-old woman presented with a severe gastric stenosis 11 years after vertical gastroplasty. We describe a side-to-side gastrogastrostomy as a safe surgical procedure to restore the physiological gastric passage after failed vertical-banded gastroplasty. CONCLUSION: Occasionally, restrictive procedures for morbid obesity cannot be converted into an alternative bariatric procedure to maintain weight control. This report demonstrates that a side-to-side gastrogastrostomy is a feasible and safe procedure
SPHERE IRDIS and IFS astrometric strategy and calibration
We present the current results of the astrometric characterization of the VLT
planet finder SPHERE over 2 years of on-sky operations. We first describe the
criteria for the selection of the astrometric fields used for calibrating the
science data: binaries, multiple systems, and stellar clusters. The analysis
includes measurements of the pixel scale and the position angle with respect to
the North for both near-infrared subsystems, the camera IRDIS and the integral
field spectrometer IFS, as well as the distortion for the IRDIS camera. The
IRDIS distortion is shown to be dominated by an anamorphism of 0.60+/-0.02%
between the horizontal and vertical directions of the detector, i.e. 6 mas at
1". The anamorphism is produced by the cylindrical mirrors in the common path
structure hence common to all three SPHERE science subsystems (IRDIS, IFS, and
ZIMPOL), except for the relative orientation of their field of view. The
current estimates of the pixel scale and North angle for IRDIS are
12.255+/-0.009 milliarcseconds/pixel for H2 coronagraphic images and
-1.75+/-0.08 deg. Analyses of the IFS data indicate a pixel scale of
7.46+/-0.02 milliarcseconds/pixel and a North angle of -102.18+/-0.13 deg. We
finally discuss plans for providing astrometric calibration to the SPHERE users
outside the instrument consortium.Comment: 12 pages, 6 figures, 3 table
CHEOPS launch in 2019! – Payload Capabilities and In-Orbit Commissioning Preview
ESA Science Programme Committee (SPC) selected CHEOPS as the first small class science mission in 2012. CHEOPS is considered as a pilot case for the implementation of “small science missions” and its success is key for the continuation of fast-paced, small missions. The mission has been developed and brought into a flight readiness state within 5-6 years from selection, which is about half the time of other ESA missions. This paper focuses on the CHEOPS payload and its predicted capabilities. The 300mm effective aperture Ritchey-Chretien telescope provided by the CHEOPS consortium has been tested and characterized on ground in a 2 months calibration campaign after the qualification for flight. The results have led to performance estimations, which are discussed here. We show that the performance requirements in flight are expected to be met by the instrument. A preview is given towards the 2 months lasting In Orbit Commissioning (IOC) phase of the CHEOPS payload after LEOP and platform check-out. The activities in orbit range from dark current measurements, PSF characterization and parasitic stray light determination to AOCS and instrument performance verifications to science validation using reference transits
The CHEOPS mission
The CHaracterising ExOPlanet Satellite (CHEOPS) was selected in 2012, as the
first small mission in the ESA Science Programme and successfully launched in
December 2019. CHEOPS is a partnership between ESA and Switzerland with
important contributions by ten additional ESA Member States. CHEOPS is the
first mission dedicated to search for transits of exoplanets using ultrahigh
precision photometry on bright stars already known to host planets. As a
follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible,
existing radii measurements or provide first accurate measurements for a subset
of those planets for which the mass has already been estimated from
ground-based spectroscopic surveys and to following phase curves. CHEOPS will
provide prime targets for future spectroscopic atmospheric characterisation.
Requirements on the photometric precision and stability have been derived for
stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS
shall be able to detect Earth-size planets transiting G5 dwarf stars in the
magnitude range between 6 and 9 by achieving a photometric precision of 20 ppm
in 6 hours of integration. For K stars in the magnitude range between 9 and 12,
CHEOPS shall be able to detect transiting Neptune-size planets achieving a
photometric precision of 85 ppm in 3 hours of integration. This is achieved by
using a single, frame-transfer, back-illuminated CCD detector at the focal
plane assembly of a 33.5 cm diameter telescope. The 280 kg spacecraft has a
pointing accuracy of about 1 arcsec rms and orbits on a sun-synchronous
dusk-dawn orbit at 700 km altitude.
The nominal mission lifetime is 3.5 years. During this period, 20% of the
observing time is available to the community through a yearly call and a
discretionary time programme managed by ESA.Comment: Submitted to Experimental Astronom
Super-Nernstian Shifts of Interfacial Proton-Coupled Electron Transfers: Origin and Effect of Noncovalent Interactions
Expected performances of the Characterising Exoplanet Satellite (CHEOPS) II. The CHEOPS simulator
Context. The CHaracterising ExOPlanet Satellite (CHEOPS) is a mission dedicated to the search for exoplanetary transits through high precision photometry of bright stars already known to host planets. The telescope will provide the unique capability of determining accurate radii for planets whose masses have already been measured from ground-based spectroscopic surveys. This will allow a first-order characterisation of the planets’ internal structure through the determination of the bulk density, providing direct insight into their composition. By identifying transiting exoplanets with high potential for in-depth characterisation, CHEOPS will also provide prime targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres. Aims. The CHEOPS simulator has been developed to perform detailed simulations of the data which is to be received from the CHEOPS satellite. It generates accurately simulated images that can be used to explore design options and to test the on-ground data processing, in particular, the pipeline producing the photometric time series. It is, thus, a critical tool for estimating the photometric performance expected in flight and to guide photometric analysis. It can be used to prepare observations, consolidate the noise budget, and asses the performance of CHEOPS in realistic astrophysical fields that are difficult to reproduce in the laboratory. Methods. The simulator has been implemented as a highly configurable tool called CHEOPSim, with a web-based user interface. Images generated by CHEOPSim take account of many detailed effects, including variations of the incident signal flux and backgrounds, and detailed modelling of the satellite orbit, pointing jitter and telescope optics, as well as the CCD response, noise and readout. Results. The simulator results presented in this paper have been used in the context of validating the data reduction processing chain, in which image time series generated by CHEOPSim were used to generate light curves for simulated planetary transits across real and simulated targets. Independent analysts were successfully able to detect the planets and measure their radii to an accuracy within the science requirements of the mission: for an Earth-sized planet with an orbital period of 50 days orbiting a Sun-like target with magnitude V = 6, the median measured value of the planet to star radius ratio, Rp/Rs, was 0.00923 ± 0.00054(stat) ± 0.00019(syst), compared to a true input value of 0.00916. For a Neptune-sized planet with an orbital period of 13 days orbiting a target with spectral type K5V and magnitude V = 12, the median measured value of Rp/Rs was 0.05038 ± 0.00061(stat) ± 0.00031(syst), compared to a true input value of 0.05.</p