Landslide susceptibility zonation in the Rio Mendoza Valley, Argentina   总被引：3，自引：4，他引：3  

Stella M. Moreiras   《Geomorphology》2005,66(1-4):345

A qualitative landslide susceptibility zonation map (scale 1:100,000) of a sector of the Río Mendoza Valley was prepared by overlapping thematic maps of conditioning factors. The main parameters affecting the distribution of landslides in the area were ranked according to slope instability. Geomorphological surveys and field observations enabled identification of 300 historical or prehistoric landslides. A landslide inventory was developed classifying the processes involved in slope instability, and analysing the degree of activity. The two most influential factors in decreasing slope stability were lithology and slope angle.  相似文献   

The discovery of 12-min X-ray pulsations from 1WGA J1958.2+3232     

G. L. Israel  L. Angelini  S. Campana  P. Giommi  L. Stella  & N. E. White 《Monthly notices of the Royal Astronomical Society》1998,298(2):502-506

During a systematic search for periodic signals in a sample of ROSAT PSPC (0.1–2.4 keV) light curves, we have discovered ∼12-min large-amplitude X-ray pulsations in 1WGA J1958.2+3232, an X-ray source which lies close to the Galactic plane. The energy spectrum is well fitted by a power law with a photon index of 0.8, corresponding to an X-ray flux level of ∼ 10⁻¹² erg cm⁻² s⁻¹. The source is probably a long-period, low-luminosity X-ray pulsar, similar to X Per, or an intermediate polar.  相似文献   

Li abundances in eclogite minerals: a clue to a crustal or mantle origin?     

Alan B. Woodland  Hans-Michael Seitz  Rainer Altherr  Horst Marschall  Bettina Olker  Thomas Ludwig 《Contributions to Mineralogy and Petrology》2002,143(5):587-601

The mineral phases of 33 eclogite and garnet clinopyroxenite samples from various tectonic settings were analysed for Li by secondary ion mass spectrometry (SIMS). In all samples, Li is preferentially incorporated into clinopyroxene (0.4 to 80 µg/g), whereas co-existing garnet contains only minor amounts of Li (0.01 to 3.7 µg/g). When present, glaucophane shows Li abundances which are similar to those of clinopyroxene, but phengite contains significantly less Li than clinopyroxene. Additional phases, such as amphibole, quartz, clinozoisite and kyanite, have low Li concentrations (<1 µg/g). No correlation is apparent between the Li contents and major-element compositions of clinopyroxene or garnet. On the basis of both measured Li concentrations in clinopyroxene and estimated Li abundances in the whole rocks, the investigated samples can be subdivided into high-Li and low-Li groups. These groups coincide with the mode of origin of the rocks. Metabasaltic (metagabbroic) eclogites from high-pressure terranes belong to the high-Li group whereas, except for one eclogite, all kimberlite- and basanite-hosted xenoliths have low Li contents. Samples from eclogites and garnet clinopyroxenites associated with orogenic peridotites fall into both groups. It is suggested that the high-Li eclogites originated from basaltic oceanic crust whereby the notable Li enrichment of some samples was probably caused by low-temperature hydrothermal alteration prior to subduction. Furthermore, the low-Li eclogites and garnet clinopyroxenites may represent high-pressure cumulates from mafic melts percolating through the mantle.  相似文献   

IV. Stratigraphie Die fazielle Einstufung fossilführender Sedimente     

Hermann Schmidt  Karl Hoffmann  Erich Brand  Wolfgang Schott  Otto Seitz  Johannes Wolburg  Franz Bettenstaedt  F. E. Hecht  Hilmar Schumann  F. Heidorn 《International Journal of Earth Sciences》1948,35(2):175-178

Ohne Zusammenfassung  相似文献   

Heterotrophic bacterial production in the Cretan Sea (NE Mediterranean)     

France Van Wambeke  Urania Christaki  Micheline Bianchi  Stella Psarra  Anastasios Tselepides 《Progress in Oceanography》2000,46(2-4)

In March and September 1995, bacterial production was measured by the ³H-leucine method in the oligotrophic Cretan Sea (Aegean Sea, Eastern Mediterranean) in the framework of the CINCS/MTP program. Samples were obtained from four stations (a coastal, a continental shelf and 2 open-sea stations) for the construction of vertical profiles of bacterial abundance and production. Bacterial production ranged from 0.1 μg C m⁻³ h⁻¹ at 1500 m depth, to 82 μg C m⁻³ h⁻¹ in March at 50 m at the coastal station. Higher bacterial integrated production was observed in March at the coastal station (131 mg C m⁻² d⁻¹ for the 0–100 m layer). Bacterial production, integrated through the water-column, was similar in March and September for the open-sea stations (60–70 mg C m⁻² d⁻¹). Relative to production, bacterial concentrations varied little between stations and seasons ranging from 9×10⁵ ml⁻¹ to 3×10⁵ ml⁻¹. Relationships between bacterial biomass and bacterial production indicated seasonal differences, likely reflecting resource limitation of bacterial biomass in March (bloom situation), and predator limitation of bacterial biomass in September (post-bloom situation).  相似文献   

Spatiotemporal distribution of copepod populations in the Gulf of Gdansk (southern Baltic Sea)     

Lidia Dzierzbicka-Glowacka  Jacek Piskozub  Jaromir Jakacki  Stella Mudrak  Maria Iwona ?mijewska 《Journal of Oceanography》2012,68(6):887-904

In the present study, we used a 3D Coupled Ecosystem Model of Baltic Sea version 1 (3D CEMBSv1) coupled with a copepod model to examine the spatiotemporal distribution of two representative copepod populations in the Gulf of Gdansk (southern Baltic Sea) including Acartia spp. and Pseudocalanus minutus elongatus. The annual cycles simulated for 2000 under realistic weather and hydrographic conditions were studied with the three-dimensional version of the coupled ecosystem-copepod model in the south-eastern Baltic Sea. The paper presents the comparison of simulated and observed copepod development at two stations in the Gulf of Gdansk. A validation of influential state variables gives confidence that the model is able to calculate reliably the stage development of dominant species in the southern Baltic Sea. The number of generations was one for P. m. elongatus and 3?C5 for Acartia spp.. A mean of five generations for the latter species per year were estimated in the coastal region and ca. three generations at the Gdansk Deep (in the open sea). Food concentration and temperature as the main factors controlling the development of the investigated copepods as well as salinity as a masking factor (i.e. salinity modifies the rate of their development) in the case of Pseudocalanus minutus elongatus are included in the present study.  相似文献   

Radial velocities in the open cluster Trumpler 14     

Hugo Levato  Stella Malaroda  Beatriz García  Nidia Morrell  Gladys Solivella  Monica Grosso 《Astrophysics and Space Science》1991,183(1):147-153

Spatially-homogenous and anisotropic Bianchi type-II and III cosmological models are obtained in Barber's second self-creation theory of gravitation both in vacuum and in the presence of perfect fluid with pressure equal to energy density. Some properties of the models are discussed.  相似文献   

Further studies on the use of classifiers for the control of wet grinding circuits     

R.A. Seitz  S.K. Kawatra 《International Journal of Mineral Processing》1984,12(4):239-249

The use of inferential particle sizing for wet grinding circuit control is well established in the literature. In this paper an analytical development is presented which yields a general inferential sizing model relating circuit product size to $\text{d}{}_{50}$ corrected for the circuits' classifier. It is then shown how the different forms of empirical equations reported in the literature can arise, depending on the range of the operating variables and the ratio of feed 50% passing size to $\text{d}{}_{50}$ corrected. Following this development, data show pilot plant and industrial plant operations to behave as predicted by the general inferential size model.  相似文献   

Bireflectance imaging of coal and carbon specimens     

J.C. Crelling  I.J. Glasspool  J.R. Gibbins  M. Seitz 《International Journal of Coal Geology》2005,64(3-4):204-216

Although bireflectance measurements are routine, to date they have been limited to selected single point measurements. This study uses a 360° rotating polarizer in the incident light path combined with digital imaging to map the optical bireflectance of a polished specimen over the complete field of view, a system herein referred to as ‘Bireflectance Imaging of Coal and Carbon Specimens’ (BRICCS). True maximum reflectance maps and maps of polarizer angle for maximum reflectance (to identify co-ordered regions) are obtainable from the same data. A variety of coal, coke, char, graphite, and carbon/carbon specimens have been examined with the BRICCS system and the results demonstrate that the system can produce accurate maximum and apparent minimum reflectance, bireflectance, and extinction angle images. For example, flakes of natural graphite show no bireflectance along their long axis except in areas that have been strained. The images are maps showing the value of every pixel that has been calibrated by mineral reflectance standards. The maps are unique in that they show fields of view that cannot be seen by normal viewing through the microscope. For example, the bireflectance maps show the maximum difference between the maximum and apparent minimum reflectances for each of the million pixels at twenty orientations of the polarizer.  相似文献   

A comparison of the tesseroid,prism and point-mass approaches for mass reductions in gravity field modelling   总被引：6，自引：3，他引：6  

B. Heck  K. Seitz 《Journal of Geodesy》2007,81(2):121-136

The calculation of topographic (and iso- static) reductions is one of the most time-consuming operations in gravity field modelling. For this calculation, the topographic surface of the Earth is often divided with respect to geographical or map-grid lines, and the topographic heights are averaged over the respective grid elements. The bodies bounded by surfaces of constant (ellipsoidal) heights and geographical grid lines are denoted as tesseroids. Usually these ellipsoidal (or spherical) tesseroids are replaced by “equivalent” vertical rectangular prisms of the same mass. This approximation is motivated by the fact that the volume integrals for the calculation of the potential and its derivatives can be exactly solved for rectangular prisms, but not for the tesseroids. In this paper, an approximate solution of the spherical tesseroid integrals is provided based on series expansions including third-order terms. By choosing the geometrical centre of the tesseroid as the Taylor expansion point, the number of non-vanishing series terms can be greatly reduced. The zero-order term is equivalent to the point-mass formula. Test computations show the high numerical efficiency of the tesseroid method versus the prism approach, both regarding computation time and accuracy. Since the approximation errors due to the truncation of the Taylor series decrease very quickly with increasing distance of the tesseroid from the computation point, only the elements in the direct vicinity of the computation point have to be separately evaluated, e.g. by the prism formulas. The results are also compared with the point-mass formula. Further potential refinements of the tesseroid approach, such as considering ellipsoidal tesseroids, are indicated.  相似文献