The new fisheries multibeam echosounder ME70: description and expected contribution to fisheries research   总被引：1，自引：0，他引：1  

Trenkel  Verena M.; Mazauric  Valerie; Berger  Laurent 《ICES Journal of Marine Science》2008,65(4):645-655

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Do river discharge rates drive the overall functioning of the pelagic ecosystem over the continental shelf of the Bay of Biscay (NE Atlantic)? A comparison of two contrasting years with special reference to anchovy (<Emphasis Type="Italic">Engraulis encrasicolus</Emphasis> L.) nutritional state     

Jean-Pierre Bergeron  Daniel Delmas  Noussithé Koueta 《Journal of Oceanography》2010,66(5):621-631

In the 2000 and 2001 springtime periods, mesozooplankton samples were systematically taken during research cruises devoted to the study of the distribution and abundance of small pelagic fishes in the French part of the Bay of Biscay, NE Atlantic, continental shelf. Simultaneous activities of three enzymes were measured in these mesozooplankton samples, to characterize the main features of ecosystem function at a regional scale. The aim was to assess assimilation rates of carbohydrates, through pyruvate kinase activity, and protein, through trypsin activity, by the mesozooplankton community and the resulting overall productivity, through aspartate transcarbamylase activity. The highest influence on the pelagic environment was the strong difference in the freshwater outflow rates from the two main large rivers, the Loire and the Gironde, which was principally responsible for the inter-annual fluctuations of the nutrients in the Bay. This overall influence of river flow results in a characteristic pattern of sea-surface salinity, which was reflected by the phytoplankton biomass distribution. Mesozooplankton enzyme activities showed high variations between the two years. The contrast in the dynamics of the pelagic food web processes between the two consecutive years, with higher activity in 2001, affected the nutritional condition of the zooplanktivorous breeding anchovy Engraulis encrasicolus.  相似文献   

The path towards high-contrast imaging with the VLTI: the Hi-5 project     

D. Defrère  O. Absil  J.-P. Berger  T. Boulet  W. C. Danchi  S. Ertel  A. Gallenne  F. Hénault  P. Hinz  E. Huby  M. Ireland  S. Kraus  L. Labadie  J.-B. Le Bouquin  G. Martin  A. Matter  A. Mérand  B. Mennesson  S. Minardi  J. D. Monnier  B. Norris  G. Orban de Xivry  E. Pedretti  J.-U. Pott  M. Reggiani  E. Serabyn  J. Surdej  K. R. W. Tristram  J. Woillez 《Experimental Astronomy》2018,46(3):475-495

The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10^??3 in the near-infrared with PIONIER (H band) and GRAVITY (K band). Nulling interferometers in the northern hemisphere and non-redundant aperture masking experiments have, however, demonstrated that contrasts of at least a few 10^??4 are within reach using specific beam combination and data acquisition techniques. In this paper, we explore the possibility to reach similar or higher contrasts on the VLTI. After reviewing the state-of-the-art in high-contrast infrared interferometry, we discuss key features that made the success of other high-contrast interferometric instruments (e.g., integrated optics, nulling, closure phase, and statistical data reduction) and address possible avenues to improve the contrast of the VLTI by at least one order of magnitude. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5 \(\upmu \)m), a sweet spot to image and characterize young extra-solar planetary systems. Finally, we address the science cases of a high-contrast VLTI imaging instrument and focus particularly on exoplanet science (young exoplanets, planet formation, and exozodiacal disks), stellar physics (fundamental parameters and multiplicity), and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed. This project is called Hi-5 for High-contrast Interferometry up to 5 μm.  相似文献   

Optical long baseline intensity interferometry: prospects for stellar physics     

Jean-Pierre Rivet  Farrokh Vakili  Olivier Lai  David Vernet  Mathilde Fouché  William Guerin  Guillaume Labeyrie  Robin Kaiser 《Experimental Astronomy》2018,46(3):531-542

More than sixty years after the first intensity correlation experiments by Hanbury Brown and Twiss, there is renewed interest for intensity interferometry techniques for high angular resolution studies of celestial sources. We report on a successful attempt to measure the bunching peak in the intensity correlation function for bright stellar sources with 1 meter telescopes (I2C project). We propose further improvements of our preliminary experiments of spatial interferometry between two 1 m telescopes, and discuss the possibility to export our method to existing large arrays of telescopes.  相似文献   

Physical properties of calcareous ooze: Control by dissolution at depth     

Thomas C. Johnson  Edwin L. Hamilton  Wolfgang H. Berger 《Marine Geology》1977,24(4):259-277

Eighteen box cores of pelagic calcareous ooze from the Ontong Java Plateau in the western equatorial Pacific were subsampled and analyzed for the following physical properties: grain size, porosity, saturated density, mean grain density, compressional sound velocity and shear strength. In addition, weight percent CaCO₃ was determined, and micropaleontological analyses of the Foraminifera were performed to determine preservation and sedimentation rates. Mean grain size of the sediments decreases at deeper depositional sites, primarily because of dissolution and fragmentation of calcareous microfossils. This, in turn, results in the sediments in deeper water having lower sound velocities and less shear strength. The physical properties of calcareous ooze are not significantly affected by any reprecipitation or incipient cementation of calcite that may occur soon after deposition.  相似文献   

Analysis of calibrated seafloor backscatter for habitat classification methodology and case study of 158 spots in the Bay of Biscay and Celtic Sea     

Ridha Fezzani  Laurent Berger 《Marine Geophysical Researches》2018,39(1-2):169-181

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