6,953 research outputs found
Post processing of differential images for direct extrasolar planet detection from the ground
The direct imaging from the ground of extrasolar planets has become today a
major astronomical and biological focus. This kind of imaging requires
simultaneously the use of a dedicated high performance Adaptive Optics [AO]
system and a differential imaging camera in order to cancel out the flux coming
from the star. In addition, the use of sophisticated post-processing techniques
is mandatory to achieve the ultimate detection performance required. In the
framework of the SPHERE project, we present here the development of a new
technique, based on Maximum A Posteriori [MAP] approach, able to estimate
parameters of a faint companion in the vicinity of a bright star, using the
multi-wavelength images, the AO closed-loop data as well as some knowledge on
non-common path and differential aberrations. Simulation results show a 10^-5
detectivity at 5sigma for angular separation around 15lambda/D with only two
images.Comment: 12 pages, 6 figures, This paper will be published in the proceedings
of the conference Advances in Adaptive Optics (SPIE 6272), part of SPIE's
Astronomical Telescopes & Instrumentation, 24-31 May 2006, Orlando, F
A strong form of the Quantitative Isoperimetric inequality
We give a refinement of the quantitative isoperimetric inequality. We prove
that the isoperimetric gap controls not only the Fraenkel asymmetry but also
the oscillation of the boundary
The giant radio halo in Abell 2163
New radio data is presented for the rich cluster Abell 2163. The cluster
radio emission is characterized by the presence of a radio halo, which is one
of the most powerful and extended halos known so far. In the NE peripheral
cluster region, we also detect diffuse elongated emission, which we classify as
a cluster relic. The cluster A2163 is very hot and luminous in X-ray. Its
central region is probably in a highly non relaxed state, suggesting that this
cluster is likely to be a recent merger. The existence of a radio halo in this
cluster confirms that halos are associated with hot massive clusters, and
confirms the connection between radio halos and cluster merger processes. The
comparison between the radio emission of the halo and the cluster X-ray
emission shows a close structural similarity. A power law correlation is found
between the radio and X-ray brightness, with index = 0.64. We also report the
upper limit to the hard X-ray emission, obtained from a BeppoSAX observation.
We discuss the implications of our results.Comment: 7 pages, 8 figures (5 in ps and 3 in gif), Accepted for publication
in Astron. Astrop
Adaptive Optics: introduction to the feature issue
This Applied Optics feature issue is a companion to the Journal of the Optical Society of America A feature issue on the same topic. The feature highlights the expansion of adaptive optics to different applications as well as its development to routine applications brought about because of significant advances in component technologies
Pupil stabilization for SPHERE's extreme AO and high performance coronagraph system
We propose a new concept of pupil motion sensor for astronomical adaptive
optics systems and present experimental results obtained during the first
laboratory validation of this concept. Pupil motion is an important issue in
the case of extreme adaptive optics, high contrast systems, such as the
proposed Planet Finder instruments for the ESO and Gemini 8-meter telescopes.
Such high contrast imaging instruments will definitively require pupil
stabilization to minimize the effect of quasi-static aberrations. The concept
for pupil stabilization we propose uses the flux information from the AO system
wave-front sensor to drive in closed loop a pupil tip-tilt mirror located in a
focal plane. A laboratory experiment validates this concept and demonstrates
its interest for high contrast imaging instrument.Comment: This paper was published in Optics Express and is made available as
an electronic reprint with the permission of OSA. The paper can be found at
http://www.opticsexpress.org/abstract.cfm?id=144687 on the OSA websit
INTEGRAL discovery of non-thermal hard X-ray emission from the Ophiuchus cluster
We present the results of deep observations of the Ophiuchus cluster of
galaxies with INTEGRAL in the 3-80 keV band. We analyse 3 Ms of INTEGRAL data
on the Ophiuchus cluster with the IBIS/ISGRI hard X-ray imager and the JEM-X
X-ray monitor. In the X-ray band using JEM-X, we show that the source is
extended, and that the morphology is compatible with the results found by
previous missions. Above 20 keV, we show that the size of the source is
slightly larger than the PSF of the instrument, and is consistent with the soft
X-ray morphology found with JEM-X and ASCA. Thanks to the constraints on the
temperature provided by JEM-X, we show that the spectrum of the cluster is not
well fitted by a single-temperature thermal Bremsstrahlung model, and that
another spectral component is needed to explain the high energy data. We detect
the high energy tail with a higher detection significance (6.4 sigma) than the
BeppoSAX claim (2 sigma). Because of the imaging capabilities of JEM-X and
ISGRI, we are able to exclude the possibility that the excess emission comes
from very hot regions or absorbed AGN, which proves that the excess emission is
indeed of non-thermal origin. Using the available radio data together with the
non-thermal hard X-ray flux, we estimate a magnetic field B ~ 0.1-0.2 mu G.Comment: 8 pages, 9 figures, accepted by A&
Effect of Ferric Sodium EDTA administration, in combination with vitamin C, folic acid, copper gluconate, zinc gluconate and selenomethionine, on cardiovascular risk evaluation: exploration of the HRV frequency domain
diseases. Using the Heart Rate Variability (HRV) analysis is possible to provide an evaluation of the safety and the
effectiveness of intervention.
Objective: To evaluate the efficacy and safety of Ferric Sodium EDTA in combination with vitamin C, folic acid, copper
gluconate, zinc gluconate and selenomethionine (Ferachel forte®) 2 tabs/day for 24 days in elderly patients with secondary
anaemia, by exploring the HRV frequency domain.
Methods: In 45 elderly patients with secondary anaemia and/or low-moderate kidney failure, laboratory values after
administration of Ferric Sodium EDTA, 2 tabs a day, in combination with vitamin C, folic acid, copper gluconate, zinc
gluconate and selenomethionine (Ferachel forte®) for 24 days (N=16 patients) or ferrous gluconate 63 mg/day added to
saline solution, administered using intravenous access during the hospitalization period of 15 ± 5 days (N=29 patients)
were evaluated. Also, ECG signals and bioelectrical impedance (BIA) were measured.
Results: Oral iron supplementation with Ferric Sodium EDTA, in combination with vitamin C, folic acid, copper gluconate,
zinc gluconate and selenomethionine (Ferachel forte®) confirmed to be effective and safe about the cardiovascular risk
in old patients. This study showed the real superiority of the oral administration about the cardiovascular risk in elderly
patients in comparison with intravenous administration of ferrous gluconate.
Conclusion: This study confirms that Ferric Sodium EDTA combination (Ferachel forte®) can be a valid alternative to ferrous
gluconate intravenous therapy (gold standard) in the treatment of secondary anaemia in elderly patients. In fact, during
the treatment, efficacy results have been maintained without statistically significant variations about cardiovascular risk,
evaluated by exploring the HRV frequency domain
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