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R. Mainieri C. Corona J. Chartoire N. Eckert J. Lopez-Saez M. Stoffel F. Bourrier 《地球表面变化过程与地形》2020,45(10):2235-2250
Rockfall release is a rather unpredictable process. As a result, the occurrence of rockfall often threatens humans and (infra)structures. The assessment of potential drivers of rockfall activity therefore remains a major challenge, even if the relative influence of rainfall, snowmelt, or freeze–thaw cycles has long been identified in short-term monitoring projects. In the absence of longer-term assessments of rockfall triggers and possible changes thereof, our knowledge of rockfall dynamics remains still lacunary as a result of the persisting scarcity of exhaustive and precise rockfall databases. Over the last decades, several studies have employed growth disturbances (GDs) in tree-ring series to reconstruct rockfall activity. Paradoxically, these series were only rarely compared to meteorological records. In this study, we capitalize on the homogeneity of a centennial-old reforestation plot to develop two reconstructions – R1 including only growth suppressions, and R2 based on injuries – with limited biases related to decreasing sample size and changes in exposed diameters back in time. By doing so, our study also and quite clearly highlights the large potential that protection forests have in terms of yielding reliable, multidecadal rockfall reconstructions. From a methodological perspective, we find no synchronicity between R1 and R2, as well as an absence of meteorological controls on rockfall processes in R1. This observation pleads for a careful selection of GDs in future reconstructions. In terms of process dynamics, we demonstrate that summer intense rainfall events (>10 mm day−1) are the main drivers for rockfall activity at our study site. Despite the stringency of our detection procedure, correlations between rockfall activity and meteorological variables remain comparable to those reported in previous studies, as a result of the complexity and multiplicity of triggering factors. We therefore call for a more systematic coupling of tree-ring analysis with rockfall and microclimatic monitoring in future studies. © 2020 John Wiley & Sons, Ltd. 相似文献
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P. Padovani D. M. Alexander R. J. Assef B. De Marco P. Giommi R. C. Hickox G. T. Richards V. Smolčić E. Hatziminaoglou V. Mainieri M. Salvato 《Astronomy and Astrophysics Review》2017,25(1):2
Active galactic nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different “flavours” in the literature that now comprise a complex and confusing AGN “zoo”. It is increasingly clear that these classifications are only partially related to intrinsic differences between AGN and primarily reflect variations in a relatively small number of astrophysical parameters as well the method by which each class of AGN is selected. Taken together, observations in different electromagnetic bands as well as variations over time provide complementary windows on the physics of different sub-structures in the AGN. In this review, we present an overview of AGN multi-wavelength properties with the aim of painting their “big picture” through observations in each electromagnetic band from radio to \(\gamma \)-rays as well as AGN variability. We address what we can learn from each observational method, the impact of selection effects, the physics behind the emission at each wavelength, and the potential for future studies. To conclude, we use these observations to piece together the basic architecture of AGN, discuss our current understanding of unification models, and highlight some open questions that present opportunities for future observational and theoretical progress. 相似文献
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C. Martayan A. Alvarez P. Bristow R. Castillo H. Dekker S. D'Odorico V. Mainieri E. Mason A. Modigliani S. Moehler P. Moller F. Patat E. Pena C. Reinero J. Vernet J. Vinther M. Vuckovic all the engineers who work a lot on X‐shooter 《Astronomische Nachrichten》2011,332(3):222-223
We report on the current performances and measurements done with X‐shooter during its first year of operations at Paranal. We present the current instrumental problems, recent and future improvements, and give advice for the observations (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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V. Mainieri D. Rigopoulou I. Lehmann S. Scott I. Matute O. Almaini P. Tozzi G. Hasinger J. S. Dunlop 《Monthly notices of the Royal Astronomical Society》2005,356(4):1571-1575
We report on the first SCUBA detection of a type 2 QSO at z = 3.660 in the Chandra Deep Field South. This source is X-ray-absorbed, shows only narrow emission lines in the optical spectrum and is detected in the submillimetre: it is the ideal candidate in an evolution scheme for active galactic nuclei (AGN) (e.g. Fabian 1999 ; Page et al. 2004 ) of an early phase corresponding to the main growth of the host galaxy and formation of the central black hole. The overall photometry (from the radio to the X-ray energy band) of this source is well reproduced by the spectral energy distribution (SED) of NGC 6240, while it is incompatible with the spectrum of a type 1 QSO (3C 273) or a starburst galaxy (Arp 220). Its submillimetre (850 μm) to X-ray (2 keV) spectral slope (αSX ) is close to the predicted value for a Compton-thick AGN in which only 1 per cent of the nuclear emission emerges through scattering. Using the observed flux at 850 μm we have derived a star formation rate of 550–680 M⊙ yr−1 and an estimate of the dust mass M dust = 4.2 × 108 M⊙ . 相似文献
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Farvacque Manon Corona Christophe Lopez-Saez J&#;r&#;me Mainieri Robin Stoffel Markus Bourrier Franck Eckert Nicolas Toe David 《Landslides》2022,19(1):7-18
Landslides - The spatial and temporal quantification of rockfall frequency remains a major challenge in mountain environments, especially also in terms of rockfall management. Approaches that have... 相似文献
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