Study of the dynamic tear film aberrations using a curvature sensing setup

The advancement in adaptive optics in recent years has increased the interest in the dynamic aberrations of the eye, including those introduced by the first optical surface provided by the tear film. A curvature sensing system to measure the dynamic topography of the tear film is described. This optical system was used to measure the aberrations of the tear film on 14 eyes. The evolution of this surface is monitored through videos of the tear film topography. The effect on optical quality is studied from the time-evolution of the RMS wavefront error showing non-negligible aberration variations attributed to the tear film layer; the effect of tear film break-up on the ocular optical quality is also discussed. Furthermore, the aberration maps are decomposed into their constituent Zernike components showing stronger contributions from 4th order terms, and also from those components with vertical symmetry which can be attributed to the effect of the eye lids on the tear film. Finally, the power spectra of the RMS wavefront error evolution show that the strongest contributions of the tear film aberrations are to be found at low frequencies, typically below 2Hz

Near-infrared mapping of spiral barred galaxies

In external galaxies, near-infrared emission originates from stellar populations, hot dust, free-free emission from H+ regions, gaseous emission, non-thermal nucleus if any. Because of the low extinction compared to the visible, infrared wavelengths are useful to probe regions obscured by dust such as central parts where starburst phenomena can occur because of the large quantity of matter. The results presented were obtained with a 32 x 32 InSb charge injection device (CID) array cooled at 4K, at the f/36 cassegrain focus of the 3m60 Canada-France-Hawaii telescope with a spatial resolution of 0.5 inches per pixel. The objects presented are spiral barred galaxies mapped at J(1.25 microns), H(1.65 microns) and K(2.2 microns). The non-axisymetric potential due to the presence of a bar induces dynamical processes leading to the confinement of matter and peculiar morphologies. Infrared imaging is used to study the link between various components. Correlations with other wavelengths ranges and 2-colors diagrams ((J-H), (H-K)) lead to the identification of star forming regions, nucleus. Maps show structures connected to the central core. The question is, are they flowing away or toward the nucleus. Observations of M83 lead to several conclusions. The star forming region, detected in the visible and the infrared cannot be very compact and must extend to the edge of the matter concentration. The general shape of the near-infrared emission and the location of radio and 10 micron peaks suggest the confinement of matter between the inner Linblad resonances localized from CO measurements about 100 and 400 pc. The distribution of color indices in the arc from southern part to the star forming region suggests an increasing amount of gas and a time evolution eventually triggered by supernova explosions. Close to the direction of the bar, a bridge-like structure connects the arc to the nucleus with peculiar color indices. Perhaps, this structure can be linked to a height velocity component seen in UV and we can attribute it to a jet and/or a matter flow along the bar toward the nucleus, fuelling it. NGC 1068 is the nearest Seyfert 2 galaxy. It has been a subject of many studies at all wavelengths. This object was mapped at J, H, K, L and M, and in polaro-imagery. Results are given

Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human eye

A system to measure the topography of the first optical surface of the human eye noninvasively by using a curvature sensor is described. The static corneal topography and the dynamic topography of the tear film can both be measured, and the topographies obtained are presented. The system makes possible the study of the dynamic aberrations introduced by the tear film to determine their contribution to the overall ocular aberrations in healthy eyes, eyes with corneal pathologies, and eyes wearing contact lenses

First NACO observations of the Brown Dwarf LHS 2397aB

Observations of the standard late type M8 star LHS 2397aA were obtained at the ESO-VLT 8m telescope ``Yepun'' using the NAOS/CONICA Adaptive Optics facility. The observations were taken during the NACO commissioning, and the infrared standard star LHS 2397aA was observed in the H, and Ks broad band filters. In both bands the brown dwarf companion LHS2397aB was detected. Using a program recently developed (Bouy et al., 2003) for the detection of stellar binaries we calculated the principal astrometric parameters (angular binary separation and position angle P.A.) and the photometry of LHS 2397aA and LHS 2397aB. Our study largely confirms previous results obtained with the AO-Hokupa'a facility at Gemini-North (Freed et al., 2003); however a few discrepancies are observed.Comment: 5 page

Les modèles numériques des microhabitats des passons : application et nouveaux développements

L'estimation des stocks de poissons que peut abriter un secteur de cours d'eau non pollué nécessite le calcul de sa capacité d'accueil en terme d'espace et de nourriture. Le premier volet a donné lieu aux Etats-Unis à la mise en place de modèles de comportement de différentes espèces de poissons en fonction de variables physiques et de modèles hydrauliques décrivant l'évolution temporelle de ces variables.Les hypothèses sous-jacentes sont discutées. Une modification du calcul de la perte de charge linéaire est préconisée pour le modèle hydraulique dans le cas des rivières à truites, et l'utilisation de méthodes multivariées est proposée pour décrire avec une meilleure fiabilité les relations entre densités de poissons et variables physiques des cours d'eau.Quelques cas d'application illustrent l'intérêt de cette démarche pour répondre à des questions posées par les gestionnaires, tant en matière de prévision des impacts piscicoles des aménagements que d'optimisation des repeuplements.When evaluating the potential fish stock that an unpolluted reach of a stream can accomodate, the load capacity with regard to space and food available must be assessed. It is for this purpose that the Instream Flow Incremental Methodology has been developed in the United States.The assumptions on which behavioural and hydraulic models are based are discussed and modifications are suggested to improve the efficiency of this methodology.The use of the Manning equation to compute the energy loss is misleading in the case of trout streams and results from simulation are more reliable when using resistance equations designed for mountain rivers.For biological monitoring, multivariate data analysis is an interesting alternative to drawing one-dimensional preference curves. Qualitative variables can be used and redundancy or dependence between parameters no longer distorts the results. The relations between physical variables of streams and a probability of the presence of fish are estimated with greater accuracy.Examples of the application of this methodology are presented with a view to assessing the effects of water abstraction on fish populations and to optimizing the restocking of trout streams

Skyrmions and the Nuclear Force

The derivation of the nucleon-nucleon force from the Skyrme model is reexamined. Starting from previous results for the potential energy of quasistatic solutions, we show that a calculation using the Born-Oppenheimer approximation properly taking into account the mixing of nucleon resonances, leads to substantial central attraction. We obtain a potential that is in qualitative agreement with phenomenological potentials. We also study the non-adiabatic corrections, such as the velocity dependent transition potentials, and discuss their importance.Comment: 24 pages, UPR-0124M

A probable giant planet imaged in the Beta Pictoris disk

Since the discovery of its dusty disk in 1984, Beta Pictoris has become the prototype of young early-type planetary systems, and there are now various indications that a massive Jovian planet is orbiting the star at ~ 10 AU. However, no planets have been detected around this star so far. Our goal was to investigate the close environment of Beta Pic, searching for planetary companion(s). Deep adaptive-optics L'-band images of Beta Pic were recorded using the NaCo instrument at the Very Large Telescope. A faint point-like signal is detected at a projected distance of ~ 8 AU from the star, within the North-East side of the dust disk. Various tests were made to rule out with a good confidence level possible instrumental or atmospheric artifacts. The probability of a foreground or background contaminant is extremely low, based in addition on the analysis of previous deep Hubble Space Telescope images. The object L'=11.2 apparent magnitude would indicate a typical temperature of ~1500 K and a mass of ~ 8 Jovian masses. If confirmed, it could explain the main morphological and dynamical peculiarities of the Beta Pic system. The present detection is unique among A-stars by the proximity of the resolved planet to its parent star. Its closeness and location inside the Beta Pic disk suggest a formation process by core accretion or disk instabilities rather than a binary-like formation process.Comment: 5 pages, 3 figures, 1 table. A&A Letters, in pres

Bound States of Heavy Flavor Hyperons

Several realistic phenomenological nucleon-nucleon interaction models are employed to investigate the possibility of bound deuteron-like states of such heavy flavor hyperons and nucleons, for which the interaction between the light flavor quark components is expected to be the most significant interaction. The results indicate that deuteron-like bound states are likely to form between nucleons and the $\Xi_c^{'}$ and $\Xi_{cc}$ charm hyperons as well as between $\Xi$ hyperons and double-charm hyperons. Bound states between two $\Sigma_c$ hyperons are also likely. In the case of beauty hyperons the corresponding states are likely to be deeply bound.Comment: 25 pages, 3 figures. Accepted Nucl. Phys.

The Wide-Field X and Gamma-Ray Telescope ECLAIRs aboard the Gamma-Ray Burst Multi-Wavelength Space Mission SVOM

The X and Gamma-ray telescope ECLAIRs is foreseen to be launched on a low Earth orbit (h=630 km, i=30 degrees) aboard the SVOM satellite (Space-based multi-band astronomical Variable Objects Monitor), a French-Chinese mission with Italian contribution. Observations are expected to start in 2013. It has been designed to detect and localize Gamma-Ray Bursts (GRBs) or persistent sources of the sky, thanks to its wide field of view (about 2 sr) and its remarkable sensitivity in the 4-250 keV energy range, with enhanced imaging sensitivity in the 4-70 keV energy band. These characteristics are well suited to detect highly redshifted GRBs, and consequently to provide fast and accurate triggers to other onboard or ground-based instruments able to follow-up the detected events in a very short time from the optical wavelength bands up to the few MeV Gamma-Ray domain.Comment: Proccedings of the "2008 Nanjing GRB Conference", June 23-27 2008, Nanjing, Chin

Impact of the European Clinical Trials Directive on prospective academic clinical trials associated with BMT

The European Clinical Trials Directive (EU 2001; 2001/20/EC) was introduced to improve the efficiency of commercial and academic clinical trials. Concerns have been raised by interested organizations and institutions regarding the potential for negative impact of the Directive on non-commercial European clinical research. Interested researchers within the European Group for Blood and Marrow Transplantation (EBMT) were surveyed to determine whether researcher experiences confirmed this view. Following a pilot study, an internet-based questionnaire was distributed to individuals in key research positions in the European haemopoietic SCT community. Seventy-one usable questionnaires were returned from participants in different EU member states. The results indicate that the perceived impact of the European Clinical Trials Directive has been negative, at least in the research areas of interest to the EBMT