Comparaison radio-endoscopique en pathologie duodénale

Pratiquées par des opérateurs expérimentés, la radiologie et l'endoscopie constituent toutes deux des méthodes d'investigations de choix dans la pathologie duodénale. Dans cette première série, peu de lésions ont été ignorées par l'une ou l'autre méthode. La radiologie reste sans doute la méthode la plus démonstrative pour mettre en évidence des infiltrations tumorales ou inflammatoires sous-muqueuses ou encore des compressions extrinsèques. Il ne fait aucun doute que, malgré l'apport de la technique radiologique du double contraste, l'endoscopie permet de mieux se rendre compte de l'importance réelle des lésions inflammatoires et ulcéreuses qui altèrent la muqueuse duodénale. Il est probable que la divergence entre les aspects endoscopiques et radiologiques observés dans certaines affections, entre autres dans les «duodénites», provienne du fait que des signes radiologiques interprétés comme étant inhérents à l'inflammation de la muqueuse traduisent en réalité soit une activité anormale de la muscularis mucosæ, soit des variations physiologiques de la morphologie du duodénum. La duodénoscopie couplée à la biopsie de la muqueuse duodénale apportera peutêtre la solution à ce problème controversé. © 1972, Springer-Verlag. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

THE 2011 JUNE 23 STELLAR OCCULTATION BY PLUTO: AIRBORNE AND GROUND OBSERVATIONS

On 2011 June 23, stellar occultations by both Pluto (this work) and Charon (future analysis) were observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 with the Kuiper Airborne Observatory resulted in the best occultation chords recorded for the event, in three visible wavelength bands. The data obtained from SOFIA are combined with chords obtained from the ground at the IRTF, the U.S. Naval Observatory Flagstaff Station, and Leeward Community College to give the detailed state of the Pluto-Charon system at the time of the event with a focus on Pluto's atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee or kink in the light curve separating them as was observed in 1988, rather than the smoothly transitioning bowl-shaped light curves of recent years. The upper atmosphere is analyzed by fitting a model to all of the light curves, resulting in a half-light radius of 1288 ± 1 km. The lower atmosphere is analyzed using two different methods to provide results under the differing assumptions of particulate haze and a strong thermal gradient as causes for the lower atmospheric diminution of flux. These results are compared with those from past occultations to provide a picture of Pluto's evolving atmosphere. Regardless of which lower atmospheric structure is assumed, results indicate that this part of the atmosphere evolves on short timescales with results changing the light curve structures between 1988 and 2006, and then reverting these changes in 2011 though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again except for the overall pressure changes. No evidence of onset of atmospheric collapse predicted by frost migration models is seen, and the atmosphere appears to be remaining at a stable pressure level, suggesting it should persist at this full level through New Horizon's flyby in 2015.United States. National Aeronautics and Space Administration (Planetary Astronomy Grant NNX10AB27G)National Research Foundation (South Africa

29 November 2011 stellar occultation by 2060 Chiron: Symmetric jet-like features

On 29 November 2011 UT, 2060 Chiron occulted a R = 14.9-mag star; data were successfully obtained at the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea and 2-m Las Cumbres Observatory Global Telescope Network (LCOGT) Faulkes Telescope North (FTN) at Haleakala. The MORIS lightcurve shows a solid-body detection of Chiron’s nucleus with a chord duration of 16.0±1.4 s, corresponding to a chord length of 158±14 km. Symmetric, dual extinction features in the FTN light curve indicate the presence of optically thick material roughly 300 km from the body midpoint. The duration of the features indicates a 3±2 km feature separated by 10–14 km from a second 7±2 km feature. The symmetry, optical thickness, and narrow size of these features allow for the intriguing possibility of a near-circular arc or shell of material

High-speed photometry of faint cataclysmic variables – viii. Targets from the catalina real-time transient survey

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Pluto's Atmospheric Structure: Results From The 2006 June 12 Stellar Occultation

Observations of the 2006 June 12 occultation by Pluto of P384.2 (McDonald & Elliot, AJ 120, 1599; UCAC2 26039859) were attempted by the MIT-Williams College collaboration from five sites in Australia and New Zealand. Four sites were successful: Black Springs, South Australia (0.8m); Mt. Canopus, Tasmania (1m); Mt. Stromlo, Australian Capital Territory (1.8m); and Siding Spring, New South Wales (2.3m). Data were recorded using Portable Occultation, Eclipse, and Transit Systems (POETS; Souza et al., in preparation). Using these data, we characterize Pluto's atmosphere and compare our results to previous occultation observations. Above half-light level, the light curves exhibit the signature of an isothermal atmosphere. The scale height is consistent at 60 km, equivalent to a temperature of 110 K for an N2 atmosphere. Below half-light level, the light curves resemble those obtained in 2002 (Pasachoff et al., AJ 129, 1718) more than 1988 (Elliot et al., Icarus 77, 148). The data drop significantly below the isothermal curve at this level, due either to a thermal gradient or extinction (or some combination); however, the drop is not as abrupt as in 1988. Data from 2002 demonstrated that at least some extinction is at work, due to the wavelength dependence of the residual flux at the bottom of the light curves (Elliot et al., Nature 424, 165). Unfortunately, we do not have multi-wavelength observations for P384.2. Our highest signal-to-noise ratio data, from the 2.3m, exhibit spikes caused by density variations in Pluto's atmosphere and interesting structure in the bottom of the light curve, when the star is probing around the limb more than vertically. Data from this event are also discussed in Elliot et al., a derivation of Pluto's atmospheric size, and Pasachoff et al., a search for satellites, rings and debris.Support partially provided by NASA grants NNG04GE48G, NNG04GF25G, and NNH04ZSS001N

On the area of accretion curtains from fast aperiodic time variability of the intermediate polar EX Hya

Contains fulltext : 127881.pdf (preprint version ) (Open Access