350 research outputs found
Smoothness, asymptotic smoothness and the Blum-Hanson property
We isolate various su cient conditions for a Banach space X to have the so-called Blum-Hanson property. In particular, we show that X has the Blum-Hanson property if either the modulus of asymptotic smoothness of X has an extremal behaviour at in nity, or if X is uniformly G^ateaux smooth and embeds isometrically into a Banach space with a 1-unconditional nite-dimensional decomposition
Etude de l'organisation spatiale du cerf rusa (Cervus timorensis russa) en Nouvelle Calédonie. Cas des biches en période de rut. Premiers résultats
Dans le cadre d'un projet de gestion d'une population de cerfs rusa (Cervus timorensis russa) sur la propriĂ©tĂ© de Gouaro-DĂ©va (Nouvelle CalĂ©donie), l'auteur a dĂ©butĂ© un travail de caractĂ©risation de l'organisation spatiale de cette espĂšce. 14 biches radio-Ă©quipĂ©es ont Ă©tĂ© lĂąchĂ©es sur le site d'Ă©tude. Le suivi par radio-tracking a Ă©tĂ© effectuĂ© pendant la pĂ©riode de rut (de juillet Ă septembre). Les rĂ©sultats ont Ă©tĂ© traitĂ©s par la mĂ©thode modifiĂ©e du polygone convexe et la taille du domaine vital ainsi caractĂ©risĂ©e varie de 60 Ă 270 hectares. Des zones de frĂ©quentations prĂ©fĂ©rentielles ont Ă©galement pu ĂȘtre dĂ©finies. Ce travail est le premier de ce type sur cette espĂšce. Il permet d'aborder certains points et de poser certaines questions. Il constitue une premiĂšre base de donnĂ©es qui ne demande qu'Ă ĂȘtre confirmĂ©e. (RĂ©sumĂ© d'auteur
Exponential population increase in the endangered Ouvéa Parakeet () after community-based protection from nest poaching
International audienceThe OuvĂ©a Parakeet (), endemic to OuvĂ©a Island (Loyalty Islands, New Caledonia, south-west Pacific), is a rainforest bird that is dependent on tree cavities for nesting. It is threatened by deforestation, but also by competition for nest sites with introduced bees, harvesting for pets, and potentially predation by introduced species. Despite these threats, we show that the OuvĂ©a Parakeet population increased exponentially from an estimated 617 (274â996) birds in 1993 to 2,090 (1,280â3,413) birds in 2009 (95% confidence interval). We explain this population increase by community-based protection measures that eliminated nest poaching. We recommend that these measures are maintained, remnant forest is protected, and the introduction of rats is prevented
Analysis of splicing patterns by pyrosequencing
Several different mRNAs can be produced from a given pre-mRNA by regulated alternative splicing, or as the result of deregulations that may lead to pathological states. Analysing splicing patterns is therefore of importance to describe and understand developmental programs, cellular responses to internal or external cues, or human diseases. We describe here a method, Pyrosequencing Analysis of Splicing Patterns (PASP), that combines RTâPCR and pyrosequencing of PCR products. We demonstrated that: (i) Ratios of two pure RNAs mixed in various proportions were accurately measured by PASP; (ii) PASP can be adapted to virtually any splicing event, including mutually exclusive exons, complex patterns of exon skipping or inclusion, and alternative 3âČ terminal exons; (iii) In extracts from different organs, the proportions of RNA isoforms measured by PASP reflected those measured by other methods. The PASP method is therefore reliable for analysing splicing patterns. All steps are done in 96-wells microplates, without gel electrophoresis, opening the way to high-throughput comparisons of RNA from several sources
Compact infrared pinhole fisheye for wide field applications
International audienceThe performances of a compact infrared optical system using advanced pinhole optics for wide field applications are given. This concept is adapted from the classical Tisse design in order to fit with infrared issues. Despite a low light gathering efficiency and a low resolution in comparison with classical lenses, pinhole imagery provides a long depth of field and a wide angular field of view. Moreover, by using a simple lens that compresses the field of view, the angular acceptance of this pinhole camera can be drastically widened to a value around 180{\textdegree}. This infrared compact system is named pinhole fisheye since it is based on the field lens of a classical fisheye system
Atmospheric Turbulence Compensation with Laser Phase Shifting Interferometry
Laser guide stars with adaptive optics allow astronomical image correction in
the absence of a natural guide star. Single guide star systems with a star
created in the earth's sodium layer can be used to correct the wavefront in the
near infrared spectral regime for 8-m class telescopes. For possible future
telescopes of larger sizes, or for correction at shorter wavelengths, the use
of a single guide star is ultimately limited by focal anisoplanatism that
arises from the finite height of the guide star. To overcome this limitation we
propose to overlap coherently pulsed laser beams that are expanded over the
full aperture of the telescope, traveling upwards along the same path which
light from the astronomical object travels downwards. Imaging the scattered
light from the resultant interference pattern with a camera gated to a certain
height above the telescope, and using phase shifting interferometry we have
found a method to retrieve the local wavefront gradients. By sensing the
backscattered light from two different heights, one can fully remove the cone
effect, which can otherwise be a serious handicap to the use of laser guide
stars at shorter wavelengths or on larger telescopes. Using two laser beams
multiconjugate correction is possible, resulting in larger corrected fields.
With a proper choice of laser, wavefront correction could be expanded to the
visible regime and, due to the lack of a cone effect, the method is applicable
to any size of telescope. Finally the position of the laser spot could be
imaged from the side of the main telescope against a bright background star to
retrieve tip-tilt information, which would greatly improve the sky coverage of
the system.Comment: 11 pages, 10 figure
Holographic Imaging of Crowded Fields: High Angular Resolution Imaging with Excellent Quality at Very Low Cost
We present a method for speckle holography that is optimised for crowded
fields. Its two key features are an iterativ improvement of the instantaneous
Point Spread Functions (PSFs) extracted from each speckle frame and the
(optional) simultaneous use of multiple reference stars. In this way, high
signal-to-noise and accuracy can be achieved on the PSF for each short
exposure, which results in sensitive, high-Strehl re- constructed images. We
have tested our method with different instruments, on a range of targets, and
from the N- to the I-band. In terms of PSF cosmetics, stability and Strehl
ratio, holographic imaging can be equal, and even superior, to the capabilities
of currently available Adaptive Optics (AO) systems, particularly at short
near-infrared to optical wavelengths. It outperforms lucky imaging because it
makes use of the entire PSF and reduces the need for frame selection, thus
leading to higher Strehl and improved sensitivity. Image reconstruction a
posteriori, the possibility to use multiple reference stars and the fact that
these reference stars can be rather faint means that holographic imaging offers
a simple way to image large, dense stellar fields near the diffraction limit of
large telescopes, similar to, but much less technologically demanding than, the
capabilities of a multi-conjugate adaptive optics system. The method can be
used with a large range of already existing imaging instruments and can also be
combined with AO imaging when the corrected PSF is unstable.Comment: Accepted for publication in MNRAS on 15 Nov 201
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