Reconstructing historical seismicity from lake sediments (Lake Laffrey, Western Alps, France)     

Jérôme Nomade  Emmanuel Chapron  Marc Desmet  Jean-Louis Reyss  Fabien Arnaud  Vincent Lignier 《地学学报》2005,17(4):350-357

Sediment archives from a mountain lake are used as indicators of seismotectonic activity in the Grenoble area (French western Alps, 45°N). Sedimentological analysis (texture and grain-size characteristics) exhibits several layers resulting from instantaneous deposits in Lake Laffrey: six debris flow events up to 8 cm thick can be attributed to slope failure along the western flank of the basin. Dating with ²¹⁰Pb and ¹³⁷Cs gamma counting techniques and the reconnaissance of historical events, provide a constrained age-depth model. Over the last 250 years, five of such debris flow deposits could be related to historical earthquakes of MSK intensities greater than VI over an area of <60 km. One debris flow deposit triggered at the beginning of the last century can be related to an historical landslide possibly triggered by the artificial regulation of the lake level.  相似文献   

Longitudinal dispersion compensation for the Very Large Telescope Interferometer     

Samuel Lévêque  Bertrand Koehler  Oskar von der Lühe 《Astrophysics and Space Science》1996,239(2):305-314

The Very Large Telescope Interferometer [1,13] will be operated in air which will introduce small optical path fluctuations due to internal turbulence [4,6] and dispersion effects. Both may contribute to fringe contrast decrease. Longitudinal dispersion effects can be corrected by inserting an appropriate glass of variable thickness in one arm of the interferometer [3,5,11,12]. This paper presents a new method applied to VLTI in order to select the optimum glass, according to both the observing wavelength and the spectral bandpath, and to calculate its thickness. Results are presented in terms of improvement on the fringe contrast.  相似文献   

A deep Chandra survey of the Groth Strip – I. The X-ray data     

K. Nandra  E. S. Laird  K. Adelberger  Jonathan P. Gardner  R. F. Mushotzky  J. Rhodes  C. C. Steidel  H. I. Teplitz  K. A. Arnaud 《Monthly notices of the Royal Astronomical Society》2005,356(2):568-586

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A 20 cm2 CCD mosaic camera for a dark matter search part I : Mechanics,optics and cryogeny     

Arnaud  M.  Aubourg  E.  Bareyre  P.  Br';ehin  S.  Caridroit  R.  de Kat  J.  Dispau  G.  Djidi  K.  Gros  M.  Lachièze-Rey  M.  Laigneau  Y.  Laurent  B.  Lesquoy  E.  Lavocat  Ph.  Magneville  C.  Mazeau  B.  Milsztajn  A.  Moscoso  L.  Pasquaud  J.  Paul  B.  Perrin  P.  Petibon  J.  Piret  Y.  Queinnec  F.  Rich  J.  Spiro  M.  de Trogoff  J.  Vigroux  L.  Zylberajch  S.  Ansari  R.  Cavalier  F.  Moniez  M.  Beaulieu  J. P.  Ferlet  R.  Grison  Ph.  Vidal-Madjar  A.  Adrianzyk  G.  Berger  J. P.  Burnage  R.  Delclite  J. C.  Kohler  D.  Magnan  R.  Richaud  A.  Guibert  J.  Moreau  O.  Tajahmady  F.  Baranne  A.  Maurice  E.  Prévôt  L.  Gry  C. 《Experimental Astronomy》1994,4(3-4):265-278

A 20cm ² CCD mosaic camera has been especially built to search for dark galactic halo objects by the gravitational microlensing effect. The sensitive area is made of 16 edge-buttable CCDs developped by Thomson-CTS, with 23×23 µm ² pixels. The 35 kg camera housing and mechanical equipment is presented. The associated electronics and data acquisition system are described in a separate paper. The camera resides at the focal plane of a 40 cm, f/10, Ferson reflector. The instrument has been in operation since December 1991 at the La Silla Observatory (ESO).  相似文献   

Leaching of lead metallurgical slags and pollutant mobility far from equilibrium conditions     

Nicolas Seignez  Arnaud Gauthier  David Bulteel  Denis Damidot  Jean-Luc Potdevin 《Applied Geochemistry》2008,23(12):3699-3711

Lead metallurgical slags are partially vitrified materials containing residual amounts of Zn, Pb, Cr, Cd and As. These hazardous materials are generally buried on heaps exposed to weathering. In this study, leaching behavior of lead blast furnace slags has been tested using pure water and open flow experiments. It appears that in such far from equilibrium and slightly acidic conditions, the main phase to be altered is the vitreous phase. As for lunar, basaltic and nuclear glasses, alkalis/proton exchanges prevail and lead to the formation of a non-protective altered layer enriched in Si, Fe and Al. The composition of the altered layer is quite constant except for Si whose concentration decreases towards the leachate interface. Owing to their sizes, micrometric Pb droplets are not always totally dissolved at the slag surface. Nevertheless, nanometric Pb droplets are instantaneously dissolved while a surrounding altered layer is formed. This leads to high Pb releases in open flow systems. Leachate chemistry and dissolution rates of the vitreous phase are closely comparable to previous leaching tests with basaltic and nuclear glasses in conditions far from equilibrium. Moreover, this study confirms that Fe is a stable element in such conditions.  相似文献   

Waves of agitation inside anchovy schools observed with multibeam sonar: a way to transmit information in response to predation   总被引：2，自引：0，他引：2  

Gerlotto  Francois; Bertrand  Sophie; Bez  Nicolas; Gutierrez  Mariano 《ICES Journal of Marine Science》2006,63(8):1405-1417

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Assessment of the effects of hydrocarbon contamination on the sedimentary bacterial communities and determination of the polar lipid fraction purity: Relevance of intact phospholipid analysis     

Nicolas Mazzella  Josiane Molinet  Agung Dhamar Syakti  Jean-Claude Bertrand  Pierre Doumenq   《Marine Chemistry》2007,103(3-4):304-317

This in situ study reports on the relevance of intact phospholipids as new biomarkers and highlights the limits of the classical fatty acid analysis after the hydrolysis of the polar lipid fraction. The analysis of polar lipid fractions revealed significant contributions of marine macrophytes with either non-phospholipid compounds (sulfoquinovosyl diacylglycerol) or with both non-bacterial phospholipid classes (phosphatidylcholine) and non-bacterial phospholipid molecular species (some molecular species of phosphatidylglycerol). The analysis of intact phospholipids showed also the predominance of gram-negative bacteria in sediments whereas the analysis of fatty acids alone cannot confirm such information. Lastly, as regard to the effects of petroleum hydrocarbons on the sedimentary bacterial communities, we observed a higher degree of saturation of the fatty acyl chains of the phospholipids extracted from sediment exposed to a massive and chronic crude oil contamination. Such a result was interpreted as an adaptive response resulting in higher membrane rigidity of the bacterial communities.  相似文献   

Combining indicator trends to assess ongoing changes in exploited fish communities: diagnostic of communities off the coasts of France   总被引：1，自引：1，他引：1  

Rochet  Marie-Joelle; Trenkel  Verena; Bellail  Robert; Coppin  Franck; Le Pape  Olivier; Mahe  Jean-Claude; Morin  Jocelyne; Poulard  Jean-Charles; Schlaich  Ivan; Souplet  Arnauld; Verin  Yves; Bertrand  Jacques 《ICES Journal of Marine Science》2005,62(8):1647-1664

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Seasonal succession of cyanoprokaryotes in a hypereutrophic oligo-mesohaline lagoon from the South of France   总被引：2，自引：0，他引：2  

Nicolas Chomrat  Robert Garnier  Cline Bertrand  Arlette Cazaubon 《Estuarine, Coastal and Shelf Science》2007,72(4):591-602

The Bolmon lagoon (South of France) is an oligo-mesohaline coastal lagoon that has undergone intense eutrophication in the past decades, resulting from a strong concentration of human activities in its drainage basin. Consequently, it exhibits some characteristics typical of an advanced trophic state; namely, the disappearance of submerged vegetation, the permanently intense phytoplankton growth and the recurrence of cyanoprokaryote blooms. As cyanoprokaryote dominance in south-temperate saline lagoons is little reported, we carried out this study in order to understand the seasonal variations in the phytoplankton composition and biomass, and to analyse the influence of environmental parameters such as salinity, nutrients and climate on the seasonal succession of species. In this lagoon, the phytoplankton was permanently dominated by cyanoprokaryotes, probably because of high availability of nutrients, low light penetration in the water column and frequent turbulent mixing induced by wind. The two most abundant species Planktothrix agardhii (in winter–spring) and Pseudanabaena limnetica (in summer) have low light requirements and are well adapted to a high mixing frequency, which defines the S1 functional group in Reynolds' typology for phytoplankton. Although widely studied in north-temperate lakes, blooms of these typically freshwater species are almost unreported in the Mediterranean area, especially in brackish ecosystems that are not their normal habitat. In the Bolmon lagoon, all their requirements for nutrients, light and mixing are satisfied and they seem to cope with a moderate presence of salt but P. agardhii was less competitive than P. limnetica at highest salinities, the latter being probably more halophytic. Contrary to the observations in lakes located at higher latitudes, the Mediterranean climate seems to induce a typical seasonal pattern of succession characterised by the dominance of P. agardhii (winter) – Chroococcales (spring) – Pseudanabaenaceae (summer) – P. agardhii (autumn, winter). The warm temperatures seemed to have a major influence on the phytoplankton succession, being responsible for the survival of Planktothrix during winter and its rapid and intense development in early spring. Intense mixing and high irradiance in summer promoted the development of Pseudanabaenaceae, as reported in another south-temperate lagoon, the Albufera of Valencia (Spain). The ecological success of Oscillatoriales observed in the Bolmon lagoon is a perfect example of a shift to the “turbid stable state” as proposed for freshwater shallow lakes only. Our work demonstrated that hypereutrophic Mediterranean lagoons can function very similarly to shallow lakes at higher latitudes; but the warmer climate and higher irradiances are probably responsible for differences in the seasonal pattern of species dominance.  相似文献   

Diel vertical behaviour, predator-prey relationships, and occupation of space by jack mackerel (Trachurus murphyi) off Chile   总被引：3，自引：0，他引：3  

Bertrand  Arnaud; Barbieri  Maria Angela; Cordova  Jose; Hernandez  Carola; Gomez  Fabian; Leiva  Francisco 《ICES Journal of Marine Science》2004,61(7):1105-1112

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