δ13C variation of soil organic matter as an indicator of vegetation change during the Holocene in central Cameroon     

Thierry Desjardins  Bruno Turcq  Jean-Pierre Nguetnkam  Gaston Achoundong  Magloire Mandeng-Yogo  Fethyé Cetin  Anne-Marie Lézine 《Comptes Rendus Geoscience》2013,345(7-8):266-271

In order to better understand the dynamics of the forest–savanna mosaic from central Cameroon, we analyzed ¹³C and ¹⁴C profiles of six oxisols: two under forests and four under savannas. The δ¹³C soil profiles collected in the forests indicate that these environments are stable at least since the mid-Holocene, whereas the areas currently covered by savannas were formerly occupied by more forested vegetations. The ¹⁴C dating of organic matter indicate that the late extension of the savannas in central Cameroon date from the Late Holocene, starting from 4000–3500 ¹⁴C yr BP.  相似文献   

Noel Cressie, Chris Wikle: Statistics for Spatio-Temporal Data     

Bruno Sansó 《Mathematical Geosciences》2013,45(2):253-254

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Satellite clock bias estimation for iGPS   总被引：4，自引：0，他引：4  

John Pratt  Penina Axelrad  Kristine M. Larson  Bruno Lesage  Richard Gerren  Nicholas DiOrio 《GPS Solutions》2013,17(3):381-389

The High Integrity GPS program seeks to provide enhanced navigation performance by combining conventional GPS with a communications and ranging broadcast from the Iridium^® Communications System. Through clock and message aiding, it would enable existing GPS receivers to acquire and track in more challenging environments. As is the case for standard GPS, accurate and precise timing is key to performance. An approach is presented for estimating the bias of each Iridium satellite clock using satellite-to-ground and satellite-to-satellite measurements. The satellite clock bias estimates are based on a Kalman filter that incorporates code-type observations from the measurements at 10 s intervals. Filter parameters are set based on the expected behavior of the clocks, allowing for discontinuous bias and frequency adjustments due to ground commands. Typical results show the current filter to be accurate to within 200 ns while always meeting the initial system specification of half a microsecond.  相似文献   

Corrigendum to “Release of neutral sodium atoms from the surface of Mercury induced by meteoroid impacts” [Icarus 177 (2005) 122-128]     

G. Cremonese  M. Bruno  S. Marchi 《Icarus》2006,182(1):297-298

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MoMaF: the Mock Map Facility     

Jérémy Blaizot  Yogesh Wadadekar  Bruno Guiderdoni  Stéphane T. Colombi  Emmanuel Bertin  François R. Bouchet  Julien E. G. Devriendt  Steve Hatton 《Monthly notices of the Royal Astronomical Society》2005,360(1):159-175

We present the Mock Map Facility, a powerful tool for converting theoretical outputs of hierarchical galaxy formation models into catalogues of virtual observations. The general principle is straightforward: mock observing cones can be generated using semi-analytically post-processed snapshots of cosmological N -body simulations. These cones can then be projected to synthesize mock sky images. To this end, the paper describes in detail an efficient technique for creating such mock cones and images from the galaxies in cosmological simulations ( galics ) semi-analytic model, providing the reader with an accurate quantification of the artefacts it introduces at every step. We show that replication effects introduce a negative bias on the clustering signal – typically peaking at less than 10 per cent around the correlation length. We also thoroughly discuss how the clustering signal is affected by finite-volume effects, and show that it vanishes at scales larger than approximately one-tenth of the simulation box size. For the purpose of analysing our method, we show that number counts and redshift distributions obtained with galics / momaf compare well with K -band observations and the two-degree field galaxy redshift survey. Given finite-volume effects, we also show that the model can reproduce the automatic plate measuring machine angular correlation function. The momaf results discussed here are made publicly available to the astronomical community through a public data base. Moreover, a user-friendly Web interface ( http://galics.iap.fr ) allows any user to recover her/his own favourite galaxy samples through simple SQL queries. The flexibility of this tool should permit a variety of uses ranging from extensive comparisons between real observations and those predicted by hierarchical models of galaxy formation, to the preparation of observing strategies for deep surveys and tests of data processing pipelines.  相似文献   

Study of the interaction between U(VI) and the anoxic corrosion products of carbon steel     

Lara Duro  Souad El Aamrani  Miquel Rovira  Joan de Pablo  Jordi Bruno 《Applied Geochemistry》2008

The objective of this study was to investigate the removal mechanism of U(VI) from groundwater by magnetite as the main product of anoxic steel corrosion. For this purpose, a systematic sequence of batch experiments was conducted to focus the active role of magnetite in the reduction of U under different conditions. Results indicated that under anoxic conditions U(VI) was sorbed at the magnetite surface, whereas under reducing conditions at different H₂(g) pressures, U was present in tetravalent form as amorphous UO₂.  相似文献   

High-resolution cyclostratigraphic analysis from magnetic susceptibility in a Lower Kimmeridgian (Upper Jurassic) marl–limestone succession (La Méouge,Vocontian Basin,France)     

Slah Boulila  Bruno Galbrun  Linda A. Hinnov  Pierre-Yves Collin 《Sedimentary Geology》2008,203(1-2):54-63

High-resolution magnetic susceptibility (MS) analysis was carried out on a Lower Kimmeridgian alternating marl–limestone succession of pelagic origin that crops out at La Méouge (Vocontian Basin, southeastern France). The aim of the study was to characterize the strong, dm-scale sedimentary cyclicity of the succession at a very high resolution, and to analyze the cycles for evidence of astronomical forcing. From marl to limestone, MS varies progressively and closely tracks the highest frequency cyclicity corresponding to the basic marl–limestone couplets. Long-term wavelength cycling modulates the high-frequency cyclicity (couplets), and appears to be controlled by clay content. Spectral analysis of the MS record reveals the presence of the complete suite of orbital frequencies in the precession, obliquity, and eccentricity (95–128 ka and 405 ka) bands with very high amplitude of the precession index cycles originating from dm-scale couplets. 405 ka-eccentricity cycles are very pronounced in the MS maxima of the marl members of the couplets, suggesting eccentricity-driven detrital input to the basin. 405 ka-orbital tuning of the MS maxima further sharpens all of the orbital frequencies present in the succession. These results are similar to those of previous studies at La Méouge that used carbonate content observed in field. Our results are also in accordance with cyclostratigraphic studies in Spain and Canada that report dominant precession index forcing. By contrast, in the Kimmeridge Clay (Dorset, UK), obliquity forcing dominates cyclic sedimentation, with weaker influence from the precession index. Ammonite zone duration estimates are made by counting the interpreted precession cycles, and provide an ultra-high resolution assessment of geologic time. In sum, this study demonstrates the power of the MS as a proxy in characterizing the high-resolution cyclostratigraphy of Mesozoic sections, particularly in alternating marl–limestone successions, and for high-resolution correlation and astronomical calibration of the geologic time scale.  相似文献   

Optimal redesign of environmental monitoring networks by using software MSANOS     

Emanuele Barca  Delia E. Bruno  Giuseppe Passarella 《Environmental Earth Sciences》2016,75(14):1082

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Preliminary report on a dinosaur tracksite from Lower Cretaceous strata in Mount Lebanon     

Raymond Gèze  Isabelle Veltz  Jean-Claude Paicheler  Bruno Granier  Roland Habchi  Dany Azar  Sibelle Maksoud 《Arabian Journal of Geosciences》2016,9(19):730

A dinosaur tracksite was discovered in Batha on the side of the road from Harissa to Ghosta (Keserwan, Lebanon). About ten trackways are exposed at the top of two beds of Lower Cretaceous limestones over an area of approximately 1000 m². These footprints were probably made by at least two dinosaur species, Sauropoda and either Theropoda or Ornithopoda. The site, which is the first record from Lebanon, should be protected to allow further scientific investigations.  相似文献   

A proposed methodology for deriving tsunami fragility functions for buildings using optimum intensity measures     

Joshua Macabuag  Tiziana Rossetto  Ioanna Ioannou  Anawat Suppasri  Daisuke Sugawara  Bruno Adriano  Fumihiko Imamura  Ian Eames  Shunichi Koshimura 《Natural Hazards》2016,80(2):1257-1278

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