36 research outputs found
Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems
Small-angle coronagraphy is technically and scientifically appealing because
it enables the use of smaller telescopes, allows covering wider wavelength
ranges, and potentially increases the yield and completeness of circumstellar
environment - exoplanets and disks - detection and characterization campaigns.
However, opening up this new parameter space is challenging. Here we will
review the four posts of high contrast imaging and their intricate interactions
at very small angles (within the first 4 resolution elements from the star).
The four posts are: choice of coronagraph, optimized wavefront control,
observing strategy, and post-processing methods. After detailing each of the
four foundations, we will present the lessons learned from the 10+ years of
operations of zeroth and first-generation adaptive optics systems. We will then
tentatively show how informative the current integration of second-generation
adaptive optics system is, and which lessons can already be drawn from this
fresh experience. Then, we will review the current state of the art, by
presenting world record contrasts obtained in the framework of technological
demonstrations for space-based exoplanet imaging and characterization mission
concepts. Finally, we will conclude by emphasizing the importance of the
cross-breeding between techniques developed for both ground-based and
space-based projects, which is relevant for future high contrast imaging
instruments and facilities in space or on the ground.Comment: 21 pages, 7 figure
The Importance of Thermal Emission Spectroscopy for Understanding Terrestrial Exoplanets
The primary objective of this white paper is to illustrate the importance of the thermal infrared in characterizing terrestrial planets leveraging our experience in characterizing extra-solar jovian worlds
Valeur de l'IRM pour le dépistage et la quantification de la stéatose et de la fibrose hépatique dans les hépatopathies chroniques
LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Ătat actuel des connaissances sur lâichtyofaune marine et dulçaquicole de la Nouvelle-CalĂ©donie, SO ocĂ©an Pacifique : diversitĂ©, exploitation, menaces et mesures de gestion.
International audienceLocated in the Southwest Pacific Ocean, the New Caledonian archipelago hosts a diversified and original ichthyofauna. Marine ecosystems host 2,339 species of fish, including ~1,450 for coral reefs alone and a total of 94 endemics, especially in deep environments. the proximity of the centre of biodiversity (the "coral triangle"), as well as a great variety of coastal habitats and their relatively good "state of health" are probably major reasons for this high species richness. Freshwaters (excluding estuaries and brackish water) have 94 species, including 12 introduced and 8 endemics. Most of these species are diadromous, essentially amphidromous, and illustrate biological traits adapted to local rivers. new Caledonian ichthyofauna is subject to various disturbances of varying intensity and/or frequency. some disturbances are natural and affect habitats rather than the fish species, such as cyclones, which can affect both coastal ecosystems (coral reefs, seagrass beds, mangroves) and freshwater ecosystems. anthropogenic pressures on ichthyofauna are of several natures. Fishing is widely practiced, both in rivers and in coastal environments and in the EEZ, but does not currently seem to pose a serious threat to targeted populations. New Caledonian aquaculture is largely focused on shrimp farming, but fish farming (currently marginal) could develop in the near future. Mining activities related to the extraction of nickel ore (and cobalt to a lesser extent) are however a much more serious problem. the potential impacts of these mining activities differ from those of cyclones, in particular by their regular (if not permanent) and non-punctual nature on the one hand, and by the fact that they considerably increase the risk of contamination of freshwater and coastal environments by metallic trace elements on the other hand. these metallic elements as well as various organic contaminants (pesticides and PCBs) are indeed found in coral reef fish. Other more specific threats concern freshwater fish, such as hydraulic developments or the proliferation of certain introduced and invasive species. For all new Caledonian aquatic ecosystems, the major issue of climate change cannot be ignored, but its impacts still remain poorly documented. About 15,000 kmÂČ of coral reef and lagoon areas have been listed as UNESCO World heritage since 2008 and are therefore protected and regulated, with regard to the activities authorized within these areas. in addition, there are more informal protections in other coastal areas where the Melanesian tribes have a customary management. Finally, various regulations exist at local authority level (environmental codes) to protect certain sensitive species.SituĂ© dans le sud-ouest de lâocĂ©an Pacifique, lâarchipel nĂ©o-calĂ©donien hĂ©berge une ichtyofaune diversifiĂ©e et originale. Les milieux marins rassemblent 2339 espĂšces de poissons, dont ~1450 pour les seuls rĂ©cifs coralliens et un total de 94 endĂ©miques, surtout en milieux profonds. La proximitĂ© du centre de biodiversitĂ© (le âtriangle de corailâ), ainsi que la trĂšs grande variĂ©tĂ© des habitats cĂŽtiers et leur relatif bon âĂ©tat de santĂ©â sont probablement des raisons majeures pour expliquer cette richesse spĂ©cifique Ă©levĂ©e. Les eaux douces (hors estuaires et eaux saumĂątres) comptent 94 espĂšces, dont 12 introduites et 8 endĂ©miques. La plupart de ces espĂšces sont diadromes et surtout amphidromes et illustrent un mode de vie adaptĂ© aux riviĂšres locales. Lâichtyofaune nĂ©o-calĂ©donienne est soumise Ă diffĂ©rentes perturbations dâintensitĂ© et/ou de frĂ©quence variables. Certaines perturbations sont naturelles et vont affecter les habitats plus que les espĂšces de poissons elles-mĂȘmes, comme par exemple les cyclones qui peuvent affecter Ă la fois les Ă©cosystĂšmes cĂŽtiers (rĂ©cifs coralliens, herbiers de phanĂ©rogames, mangroves) et dâeaux douces. Les pressions anthropiques sur lâichtyofaune sont de plusieurs natures. La pĂȘche est largement pratiquĂ©e, tant en riviĂšre quâen milieux cĂŽtiers et dans la ZEE, mais ne semble pas actuellement constituer une grave menace pour les populations ciblĂ©es. Lâaquaculture nĂ©o-calĂ©donienne est trĂšs largement focalisĂ©e sur la crevetticulture, mais la pisciculture (actuellement marginale) pourrait se dĂ©velopper dans les annĂ©es Ă venir. Les activitĂ©s miniĂšres en lien avec lâextraction du nickel (et accessoirement du cobalt) sont une problĂ©matique nettement plus sĂ©rieuse. Les impacts potentiels de ces activitĂ©s miniĂšres diffĂšrent de ceux des cyclones notamment par leur cĂŽtĂ© rĂ©gulier (sinon permanent) et non ponctuel dâune part, et par le fait quâils accroissent considĂ©rablement le risque de contamination des milieux dulçaquicoles et cĂŽtiers par des Ă©lĂ©ments traces mĂ©talliques dâautre part. Ces Ă©lĂ©ments mĂ©talliques ainsi que divers contaminants organiques (pesticides et PCBs) sont en effet retrouvĂ©s dans les poissons coralliens. Dâautres menaces plus spĂ©cifiques concernent les poissons dâeau douce, comme les amĂ©nagements hydrauliques ou encore la prolifĂ©ration de certaines espĂšces introduites et invasives. Pour tous les Ă©cosystĂšmes aquatiques nĂ©o-calĂ©doniens, lâenjeu majeur du changement climatique ne peut ĂȘtre ignorĂ©, mais ses impacts restent encore peu documentĂ©s. Environ 15 000 kmÂČ de zones rĂ©cifo-lagonaires sont inscrites au Patrimoine Mondial de lâUNESCO depuis 2008 et sont, de ce fait, protĂ©gĂ©es et rĂšglementĂ©es. Ă ceci sâajoute des protections plus informelles dans dâautres secteurs cĂŽtiers oĂč les tribus mĂ©lanĂ©siennes assurent une gestion coutumiĂšre. Enfin, diverses rĂšglementations existent au niveau des collectivitĂ©s locales (codes de lâenvironnement) pour protĂ©ger certaines espĂšces sensibles
Giuris (teleostei : eleotridae) dâindonĂ©sie, avec description dâune espĂšce nouvelle.
International audienceIndonesian Giuris species are reviewed and compared to the known species described from the area. Three species are recognized including one new species, which is described in this paper using genetic and morphomeristic approaches. The three species differ by a high percentage of divergence in partial COI gene (652 bp) and by several characters including the number of pectoral fin rays, the scales in transverse forward series, the scales around the eye and the interorbital length.Des spĂ©cimens de Giuris provenant dâindonĂ©sie ont Ă©tĂ© Ă©tudiĂ©s et comparĂ©s aux espĂšces dĂ©crites de la rĂ©gion. Trois espĂšces ont Ă©tĂ© rĂ©pertoriĂ©es dont une nouvelle, qui est dĂ©crite dans cet article en utilisant des approches gĂ©nĂ©tique et morphomĂ©ristique. Les trois espĂšces diffĂšrent par un fort pourcentage de divergence au niveau du gĂšne COI partiel (652 pb) et par plusieurs caractĂšres incluant, principalement, le nombre de rayons aux nageoires pectorales, le nombre dâĂ©cailles en sĂ©rie transverse antĂ©rieure, lâespace interorbitaire et le nombre dâĂ©cailles autour de lâĆil
Premier signalement dâHippichthys albomaculosus Jen- kins & Mailautoka, 2010 (syngnathidae) en Nouvelle-CalĂ©donie.
International audienceThree specimens of Hippichthys albomaculosus Jenkins and Mailautoka, 2010, only known from Fiji, were recently collected from the North Province of New Caledonia. Morphomeristic values confirm the identity of specimens. This study constitutes the first record of this species in New Caledonia and outside of its type locality.Trois spécimens d'Hippichthys albomaculosus Jenkins & Mailautoka, 2010, connu uniquement des Fidji, ont été récemment collectés dans la province Nord de la Nouvelle-Calédonie. Les valeurs morpho-méristiques confirment l'identité des spécimens. Cette étude constitue le premier signalement de cette espÚce en Nouvelle-Calédonie et hors de sa localité type
Giuris (Teleostei : Eleotridae) from Indonesia, with description of a new species
Indonesian Giuris species are reviewed and compared to the known species described from the area. Three species are recognized including one new species, which is described in this paper using genetic and morphomeristic approaches. The three species differ by a high percentage of divergence in partial COI gene (652 bp) and by several characters including the number of pectoral fin rays, the scales in transverse forward series, the scales around the eye and the interorbital length
Eleotris (Teleostei: Eleotridae) from Indonesia with Description of Three New Species Within the âmelanosomaâ Neuromast Pattern Group
International audienc