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81.
Nikolai Kiselev Vera Rosenbush Klaus Jockers Sergey Velichko Sen Kikuchi 《Earth, Moon, and Planets》2005,97(3-4):365-378
We present the electronic database (EAR-C-COMPIL-5-DB-COMET-POLARIMETRY-V1.0, NASA Planetary Data System) involving published and some unpublished results of cometary polarimetry. The database contains more than 2600 measurements of linear and circular polarization for 64 comets since 1940s. The narrow-band and wide-band measurements within the spectral region 0.3–2.2 micron are presented. The ranges of phase angles, helio- and geocentric distances of comets are 0.4–122°, 0.6–4.8 AU, 0.03–4.9 AU, respectively. We have comprised more than 60 references to the published papers and unpublished sources. The data we included are presented in a tabular format in the ASCII codes. The database can be used as the observational basis for detailed theoretical modeling, interpretation of the phase-angle and spectral dependence of polarization, classification of comets, laboratory simulating, and for selecting future space-mission targets. Analysis of the available data allowed us to summarize some observed characteristics of linearly and circularly polarized light and their phase-angle, heliocentric, spectral, and spatial dependencies. 相似文献
82.
Ralph Bridle Nikolai Barsoukov Mohammad Al-Homaili Robert Ley Ameerah Al-Mustafa 《Geophysical Prospecting》2006,54(6):667-680
We present a seismic Test Line, provided by Saudi Aramco for various research teams, to highlight a few major challenges in land data processing due to near‐surface anomalies. We discuss state‐of‐the‐art methods used to compensate for shallow distortions, including single‐layer, multilayer, plus/minus, refraction and tomostatics methods. They are a starting point for the new technologies presented in other papers, all dealing with the same challenging data described here. The difficulties on the Test Line are mostly due to the assumption of vertical raypaths, inherent in classical applications of near‐surface correction statics. Even the most detailed velocity/depth model presents difficulties, due to the compleX‐raypath. There is a need for methods which are based on more complex models andtheories. 相似文献
83.
Eric A. Jerde Lawrence A. Taylor Ghislaine Crozaz Nikolai V. Sobolev 《Contributions to Mineralogy and Petrology》1993,114(2):148-159
Eclogite xenoliths from the mantle have experienced a wide variety of processes and P-T conditions, many of which are recorded in the mineral compositions and textures. Exsolution of garnet from clinopyroxene is one such texture, occurring in a minority of mantle eclogites. New analyses of clinopyroxene and garnet of eclogite xenoliths from kimberlites at Bellsbank (South Africa) and Obnazhënnaya (Yakutia, Russia) are presented here, and these are combined with data from the literature. Exsolution of garnet from clinopyroxene is generally lamellar, although lens-shaped garnets are also present. Major- and trace-element characteristics show a wide range of compositions and include eclogite Groups A, B, and C. Rare-earth element (REE) concentrations of garnet and pyroxene were determined by SIMS, and the REE patterns are subtly different from those in ordinary eclogites. Differences include the absence of prominent Eu anomalies in samples of this study and differences in the slopes of chondrite-normalized REE patterns. It is possible that these signatures are unique to exsolved eclogites, a result of subsolidus elemental partitioning during exsolution. Some reconstructed whole-rock compositions are aluminuous; comparison with ordinary eclogites shows only minor differences, implying a similar origin. If the immediate precursor to the exsolved eclogites was a monomineralic pyroxenite, the excess aluminium was tied up in Tschermak's molecule, although the occasional presence of kyanite exsolution lamellae is indicative of a Ca-Eskola component. Reconstructed pyroxenes from kyanite- and corundum-rich samples contain unrealistic amounts of aluminium for mantle pyroxenes. A protolith (or parental pyroxene) threshold of 24% Al2O3 may exist, above which (as in a plagioclase cumulate) the final assemblage is kyanite- and/or corundum-bearing. 相似文献
84.
Sergey Alexandrovich Gorbarenko Evgenia L’vovich Goldberg Michaele Kashgarian Tat’yana Alekseevna Velivetskaya Sergey Petrovich Zakharkov Vladimir Stepanovich Pechnikov Alexandr Anatol’evich Bosin Olga Yur’evna Psheneva Elena Diamilevna Ivanova 《Journal of Oceanography》2007,63(4):609-623
The paper presents the records of several paleoproductivity proxies (PP) (biogenic opal and Ba (Si_bio, Ba_bio), organic carbon
(C_org) and carbonate Ca_carb, chlorin and benthic foraminifera abundance (BFA)) in sediments of the Okhotsk Sea for the last
80 kyr with a resolution of ∼100–300 years. The sediment age model was based on the AMS 14C data, records of benthic foraminifera δ18O, paleointensity of the Earth’s geomagnetic field and magnetic susceptibility. PP values demonstrate series of severe prolonged
productivity drops in the Okhotsk Sea followed by a sharp increase during the last glaciation. On the basis of quantitative
estimations of the paleoproductivity in the Okhotsk Sea during the cold MIS 2 and warm Holocene (Gorbarenko and Goldberg,
2005), it is suggested that the millennium scale relationship in productivity-climate changes of this basin was similar: an
increase in the sea’s productivity was related with regional climate warming and vice-versa. The PP records of productivity/climate
oscillations in the Okhotsk Sea during MIS 2–4 occurred contemporaneously with the North Atlantic cold Heinrich events (HE)
and Greenland Dansgaard-Oyeshger interstadial (DOI). Observed successions of prolonged climate cooling events followed by
rapid, abrupt warming are similar to climate and environmental oscillations in the N. Atlantic and Greenland, that confirms
the millennium-scale climate changes synchronicities in the Northern Hemisphere including the far NW Pacific, the hydrology
and climate conditions of which are close to those of the Okhotsk Sea. Synchronism of the N. Hemisphere severe cooling (including
the Okhotsk Sea) with the Antarctic warming suggests that mechanisms of the “seesaw” effect (Blunier and Brook, 2001) in the
low latitude heat redistribution between high latitudes of both hemispheres were more complicated than direct NADW formation
forcing and encompasses the global atmospheric reorganization. Within the PP used a closer connection in the Okhotsk Sea millennium
oscillations was observed for the C_org, BFA and chlorin; Ba_bio increases more closely to DOI. Si_bio variability does not
show any evident correlation with productivity changes. 相似文献
85.
Nikolai Maximenko 《Journal of Oceanography》2004,60(4):681-687
The 20–30% differences between drifter- and altimetry-derived mean velocities reported at the ASUKA line (Affiliated Surveys
of the Kuroshio off Cape Ashizuri) are explained in terms of the non-Eulerian character of statistics of drifter trajectories'
crossovers with the TOPEX/Poseidon track. Larger mean drifter velocities are shown to result from the fact that more water
crosses the line when velocity is large, so that the “line” average velocity corresponds to the Eulerian quantity <V⋅|Vn|>/<|Vn|>, where Vn is a velocity component perpendicular to the line. Practical methods are suggested to correct the bias. General properties
of the “line” statistic and improvement of dynamical balance by correct accounting for the acceleration term are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
86.
Fatal landslides in Europe 总被引:4,自引:3,他引:1
Ubydul Haque Philipp Blum Paula F. da Silva Peter Andersen Jürgen Pilz Sergey R. Chalov Jean-Philippe Malet Mateja Jemec Auflič Norina Andres Eleftheria Poyiadji Pedro C. Lamas Wenyi Zhang Igor Peshevski Halldór G. Pétursson Tayfun Kurt Nikolai Dobrev Juan Carlos García-Davalillo Matina Halkia Stefano Ferri George Gaprindashvili Johanna Engström David Keellings 《Landslides》2016,13(6):1545-1554
Landslides are a major hazard causing human and large economic losses worldwide. However, the quantification of fatalities and casualties is highly underestimated and incomplete, thus, the estimation of landslide risk is rather ambitious. Hence, a spatio-temporal distribution of deadly landslides is presented for 27 European countries over the last 20 years (1995–2014). Catastrophic landslides are widely distributed throughout Europe, however, with a great concentration in mountainous areas. In the studied period, a total of 1370 deaths and 784 injuries were reported resulting from 476 landslides. Turkey showed the highest fatalities with 335. An increasing trend of fatal landslides is observed, with a pronounced number of fatalities in the latest period from 2008 to 2014. The latter are mostly triggered by natural extreme events such as storms (i.e., heavy rainfall), earthquakes, and floods and only minor by human activities, such as mining and excavation works. Average economic loss per year in Europe is approximately 4.7 billion Euros. This study serves as baseline information for further risk mapping by integrating deadly landslide locations, local land use data, and will therefore help countries to protect human lives and property. 相似文献
87.
Radomir Petrovich 《Geochimica et cosmochimica acta》1981,45(10):1665-1674
The extensive evidence on the properties of ground quartz such as grain morphology and adherence and subsurface structural damage shows a consistent pattern, interpretable in terms of the competing processes of fracture and of local plastic deformation.The well-documented pattern of dissolution of ground quartz in aqueous solutions is also consistent. At large undersaturations and constant other environmental variables, the apparent dissolution rate of ground quartz decreases exponentially with the increasing thickness of the equivalent dissolved disturbed layer, and the rate of release of adherent tiny fragments shows roughly the same dependence on the latter. At small undersaturations distribution of solubilities also needs to be considered. 相似文献
88.
Jonelle Nikolai Crisostomo Jeddalyn Parian Daizo Ishiyama Redempta Baluda Sonia Eguia Jocelyn Galapon Gerry Comia Jessie Segura Maureen Laroco Noel Oliveros Victor B. Maglambayan 《Resource Geology》2007,57(2):241-247
Two ore and three alteration types were identified in the Lascogon Project of Philex Gold Philippines, in Surigao del Norte, Mindanao Island, Philippines. The jasperoid ore is the host to the Carlin‐like gold mineralization in the Lascogon and Danao prospects. The ore occurs in a decalcified and silicified horizon, with minor chlorite and goethite, stibnite, pyrite and quartz crystals ranging from cryptocrystalline to botryoidal. The stringer–stockwork type Cu‐Au mineralization in the Suyoc prospect is hosted in argillized andesitic rocks of the Mabuhay Formation. The primary ore minerals are chalcopyrite with minor amounts of sphalerite. The alteration types identified are propylitic alteration, argillic alteration and silicification. The propylitized basaltic and andesitic flows of the Bacuag Formation bound the jasperoid mineralization in the Lascogon prospect. Stratigraphically, the relationship between propylitized basalts and stringer–stockwork Cu‐Au is not clear but a lateral change can be inferred from jasperoid in the center and stringer–stockwork towards the east. 相似文献
89.
Mikhail Yu. Gershenzon Sergeid. Il'in Nikolai G. Fedotov Yulii M. Gershenzon Elena V. Aparina Vladislav V. Zelenov 《Journal of Atmospheric Chemistry》1999,34(1):119-135
A simple kinetic mechanism of nitrate radicals uptake on dry sea-salt NaCl, NaBr surfaces is proposed. The mechanism includes adsorption/desorption equilibrium and unimolecular decomposition of the adsorbed complex: NO3(g) + NaX(s) (NO3-NaX)(s); (NO3-NaX)(s) NaNO3 + X(s) Two techniques were used: the matrix isolation ESR and mass spectrometry. The uptake coefficient () is found to be dependent on exposure time of salt to NO3 for raw coating. The initial (t0) is higher than the observable steady-state obs. At room temperature obs is independent of [NO3] at low [NO3] = 3 × 109 - 1011 cm-3, but it is inversely proportional to [NO3] at concentrations higher than 1012 cm-3. At temperatures above 100 °C, obs becomes independent of [NO3] in a wider range of [NO3]. An increased number of dislocations is supposed to exist in the case of raw coating. Due to a wide spread of the surface sites binding energy with the ionic lattice near dislocations, the part of surface complexes has lower binding energy and "burns" more rapidly. That burning determines the transition from (t0) down to obs.The kinetic parameters and elementary rate coefficients are obtained. The recommended for low atmospheric NO3 concentration are in the range of 0.002 ± 0.04 for NaCl and 0.1-0.3 for NaBr depending on a mechanism of the (t) relaxation. 相似文献
90.
Andrey Petrovich Fedotov Michael A. Phedorin Mark De Batist Galina A. Ziborova Alexsey Yu Kazansky Michael Yu Semenov Galina G. Matasova Andrey V. Khabuev Sergey A. Kugakolov Sergey V. Rodyakin Svetlana M. Krapivina Tom Pouls 《Journal of Paleolimnology》2008,39(3):335-348
We use high-resolution reflection seismic data and detailed grain-size analysis of a drill core (KDP-01) from Lake Khubsugul
(northern Mongolia) to provide an improved reconstruction of the glacial history of the area for the last 450 ka. Grain-size
analysis of suspended sediment load in modern rivers draining into the lake and of moraine material from the northern part
of the catchment shows that the silt fraction is transported to the central part of the lake mainly by river suspension, whereas
the clay fraction is mainly transported by glacial meltwater during deglaciation. The changes in of the clay/silt ratio in
Lake Khubsugul sediments correlates well with the standard global paleoclimate records: low clay/silt ratios indicate warm
climates, while a high clay/silt ratio reflects glacial erosion and cold climates. Pulses of clay input into the lake occur
at the final stages of glacial periods (i.e., glacial maxima and subsequent onsets of deglaciation). The periodicity in glacial
clay input in Lake Khubsugul is in tune with global periods of deglaciation, but there are differences in the intensity of
the deglacial events for MIS-12 and MIS-2. These differences are attributed to specific conditions in regional distribution
of moisture during glaciation, glacial ice volumes, and solar insolation intensity at the onset of deglaciation. Deglaciation
of the Khubsugul glaciers occurred in response to an increase in summer solar insolation above a threshold value of 490 W/m2. Two types of deglaciation can be distinguished: (1) slow melting during several tens of 1,000 years during weak increases
in summer insolation, and (2) short and fast melting during several thousands of years in response to strong increases in
summer insolation. The maximum ice volume in the area of Lake Khubsugul during the past 450 ka occurred during the period
of 373–350 ka BP (MIS 11a-10) and was caused by high levels of moisture in the region, whereas the MIS-2 and MIS-12 glacial
periods were characterized by minima in ice volume, due to the strong aridity in the region. 相似文献