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1.
A. Arjannikova C. Larroque J. -F. Ritz J. Déverchère J. F. Stéphan S. Arjannikov V. San'kov 《地学学报》2004,16(5):265-272
We used satellite imagery and field data to investigate the south‐westernmost Baikal rift zone. We focus our study in the Mondy and Ikhe Ukhgun valleys, site of an Mw = 6.9 seismic event in 1950. Surface deformations are observed along the E–W‐trending Mondy strike‐slip fault and along the Ikhe Ukhgun thrust. The Mondy fault system is 80 km long and is composed of four segments 10–15 km long. These segments are characterized by subvertical planes with left‐lateral movements. The Ikhe Ukhgun thrust is 20 km long, dips 40° to the south and shows reverse movement with a left‐lateral component. These observations are consistent with the present‐day regional NNE–SSW compression and with the focal mechanism of the 1950 Mondy earthquake that was recently re‐evaluated. These features, like those observed in the Tunka basin, demonstrate a recent change of regional strain regime from transtension to transpression that we place before the Late Pleistocene. 相似文献
2.
Continuous wavelet analyses of hourly time series of air temperature, stream discharge, and precipitation are used to compare the seasonal and inter‐annual variability in hydrological regimes of the two principal streams feeding Bow Lake, Banff National Park, Alberta: the glacial stream draining the Wapta Icefields, and the snowmelt‐fed Bow River. The goal is to understand how water sources and flow routing differ between the two catchments. Wavelet spectra and cross‐wavelet spectra were determined for air temperature and discharge from the two streams for summers (June–September) 1997–2000, and for rainfall and discharge for the summers of 1999 and 2000. The diurnal signal of the glacial runoff was orders of magnitude higher in 1998 than in other years, indicating that significant ice exposure and the development of channelized glacial drainage occurred as a result of the 1997–98 El Niño conditions. Early retreat of the snowpack in 1997 and 1998 led to a significant summer‐long input of melt runoff from a small area of ice cover in the Bow River catchment; but such inputs were not apparent in 1999 and 2000, when snow cover was more extensive. Rainfall had a stronger influence on runoff and followed quicker flow paths in the Bow River catchment than in the glacial catchment. Snowpack thickness and catchment size were the primary controls on the phase relationship between temperature and discharge at diurnal time scales. Wavelet analysis is a fast and effective means to characterize runoff, temperature, and precipitation regimes and their interrelationships and inter‐annual variability. The technique is effective at identifying inter‐annual and seasonal changes in the relative contributions of different water sources to runoff, and changes in the time required for routing of diurnal meltwater pulses through a catchment. However, it is less effective at identifying changes/differences in the type of the flow routing (e.g. overland flow versus through flow) between or within catchments. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
3.
The polarimetric survey of electrons in the K-corona initiated at Pic-du-Midi and Meudon Observatories in 1964 now covers a full solar cycle of activity. The measurements are photometrically calibrated in an absolute scale.In June 1967 a persistent coronal feature was fan-shaped as a lame coronale above quiescent prominences. We deduce an electron density of N
0 = 1.5 × 108 at 60 000 km above the photosphere, a total number of 14 × 1039 electrons, a hydrostatic temperature of 1.7 × 106 K, and a total thermal energy 3N
eKT = 1.0 × 1031 ergs. When a center of activity appeared, a major localized condensation developed to replace the old elongated feature, with N
0 = 4.5 × 108, a total of 4.5 × 1039 electrons and the same temperature of 1.7 × 106 K.Also, a fan-shaped feature of exceptional intensity was analysed on 8 September 1966, with N
0 = 6 × 108 and a total of 24 × 1039 electrons.Fan-shaped features are frequent above quiescent prominences. They degenerate above a height of 2R
into thinner isolated columns or blades with temperatures also around 1.7 × 106 K. 相似文献
4.
The results of evolutionary computations for massive binary systems (initial masses of the primary 10M
) with mass ratios between 0.3 and 0.8 are summarized and compared with observations in order to verify how far one can go with the conservative assumption of mass exchange. It is found that conservative mass exchange leads to acceptable first-order models of W-R and massive X-ray binaries. However, the comparison between this theory and observation reveals that for the observed systems (W-R and X-ray binaries) a preference exists for low intial mass ratios; moreover, the X-ray luminosities of the theoretical models are systematically too low, though this may be due to the adopted wind model. In addition, the influences of several parameters (distance between the components, chemical composition, primary mass, mass ratio and atmosphere) are examined. These parameters influence the remnant mass and any further evolution only marginally. Attention is also given to the effect on the system parameters of a supernova explosion of the remnant of the mass-losing component. For a large range of systems a disruption probability smaller than 25% is found. 相似文献
5.
H. Tissoux H. Valladas P. Voinchet J.L. Reyss N. Mercier C. Falguères J.-J. Bahain L. Zöller P. Antoine 《Quaternary Geochronology》2010,5(2-3):131-136
As part of a chronological study of the famous Upper Pleistocene Nussloch (Germany) loess sequence, three samples were collected to check the applicability of palaeodosimetric dating methods (OSL and ESR) to quartz grains. The ESR-multicentre method showed a partial bleaching of the ESR centers in aeolian sands. This partial bleaching was also observed by OSL. Laminated loess seemed to be sufficiently bleached but showed a large scatter of the doses, which we ascribed to heterogeneous responses of the luminescent grains to the SAR protocol. Ages could nevertheless be calculated for the three samples and were found to be somewhat older than the IRSL and 14C ages obtained for the same layers of the laminated loess. 相似文献
6.
P. Petit B. Dintrans S. K. Solanki J.-F. Donati M. Aurière F. Lignières J. Morin F. Paletou J. Ramirez C. Catala R. Fares 《Monthly notices of the Royal Astronomical Society》2008,388(1):80-88
From a set of stellar spectropolarimetric observations, we report the detection of surface magnetic fields in a sample of four solar-type stars, namely HD 73350, HD 76151, HD 146233 (18 Sco) and HD 190771. Assuming that the observed variability of polarimetric signal is controlled by stellar rotation, we establish the rotation periods of our targets, with values ranging from 8.8 d (for HD 190771) to 22.7 d (for HD 146233). Apart from rotation, fundamental parameters of the selected objects are very close to the Sun's, making this sample a practical basis to investigate the specific impact of rotation on magnetic properties of Sun-like stars.
We reconstruct the large-scale magnetic geometry of the targets as a low-order (ℓ < 10) spherical harmonic expansion of the surface magnetic field. From the set of magnetic maps, we draw two main conclusions. (i) The magnetic energy of the large-scale field increases with rotation rate. The increase in chromospheric emission with the mean magnetic field is flatter than observed in the Sun. Since the chromospheric flux is also sensitive to magnetic elements smaller than those contributing to the polarimetric signal, this observation suggests that a larger fraction of the surface magnetic energy is stored in large scales as rotation increases. (ii) Whereas the magnetic field is mostly poloidal for low rotation rates, more rapid rotators host a large-scale toroidal component in their surface field. From our observations, we infer that a rotation period lower than ≈12 d is necessary for the toroidal magnetic energy to dominate over the poloidal component. 相似文献
We reconstruct the large-scale magnetic geometry of the targets as a low-order (ℓ < 10) spherical harmonic expansion of the surface magnetic field. From the set of magnetic maps, we draw two main conclusions. (i) The magnetic energy of the large-scale field increases with rotation rate. The increase in chromospheric emission with the mean magnetic field is flatter than observed in the Sun. Since the chromospheric flux is also sensitive to magnetic elements smaller than those contributing to the polarimetric signal, this observation suggests that a larger fraction of the surface magnetic energy is stored in large scales as rotation increases. (ii) Whereas the magnetic field is mostly poloidal for low rotation rates, more rapid rotators host a large-scale toroidal component in their surface field. From our observations, we infer that a rotation period lower than ≈12 d is necessary for the toroidal magnetic energy to dominate over the poloidal component. 相似文献
7.
Yannick Giraud-Héraud Jean Kaplan François De Volnay Martin Charling Tao Sylvaine Turck-Chièze 《Solar physics》1990,128(1):21-33
The Saclay solar evolution code is used to check the effect of WIMPs on solar evolution. In this paper we study the effects of various types of Cosmion-matter interactions, give constraints on the crosssections compatible with the measured neutrino rate of 2 SNU on chlorine, and relate these constraints to ongoing dark matter detection experiments.Unité associée au CNRS UA 280, F-75251 Paris Cedex 05, France.On leave from LPC, Collège de France. 相似文献
8.
Joel Sanchez-Bermudez Florentin Millour Fabien Baron Roy van Boekel Laurent Bourgès Gilles Duvert Paulo J. V. Garcia Nuno Gomes Karl-Heinz Hofmann Thomas Henning Jacob W. Isbell Bruno Lopez Alexis Matter J-Uwe Pott Dieter Schertl Eric Thiébaut Gerd Weigelt John Young 《Experimental Astronomy》2018,46(3):457-473
During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u ? v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction. 相似文献
9.
Massimo Aranzulla Flavio Cannavò Simona Scollo Giuseppe Puglisi Giuseppina Immè 《GPS Solutions》2013,17(4):485-497
We investigate the ability of GPS to detect volcanic plumes at Mt. Etna, Italy. We use a robust statistical approach to highlight whether the presence of a volcanic plume in the atmosphere may really affect the GPS undifferenced post-fit phase residuals. The proposed method has been tested for the September 4–5, 2007 activity of Mt. Etna. This eruption produced powerful lava fountains forming a weak, a few kilometers high plume for several hours, representing typical activity at Etna over the last 5 years. We analyzed data from nineteen Etna permanent GPS stations located on the volcano flanks at different heights and applied a statistical test based on four main steps: (a) realization of a simplified model representing the volcanic plume in atmosphere; (b) evaluation of the GPS satellite and station couples intersecting the plume; (c) calculation of the volcanic plume region crossed by the GPS signal; (d) application of a robust statistical test in order to see whether the volcanic plume affected the GPS signals. Results show that during the September 4–5, 2007 explosive activity, the GPS residuals definitely include the contribution of the volcanic plume. Our analysis shows that values of the GPS residuals are ten times smaller than those found for the Miyakejima eruption (Japan), highlighting a likely relationship between residuals and eruption intensity. In the future, data derived from the GPS stations located on Etna’s flanks could be used to improve the alerting system of volcanic ash, already operating at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo. 相似文献
10.
Berny Sèbe 《The Cartographic journal》2013,50(1):91-92
AbstractSince the publication of the first waterway map in 1990, the Inland Waterways of Britain series has expanded to a total of twenty three individual maps, a national route planning map, the first ring atlas and a directory of the inland waterways which explores aspects of preservation, restoration and heritage. Many of the titles have featured in walking guides, directories, promotional literature and web sites. This paper outlines the development of the series from the first map, describing the maps themselves, tracking the evolution of production methodologies, defining marketing and sales strategies and discussing the decision-making processes behind the publication and introduction of new titles. 相似文献