Automated mapping of rock slope geometry,kinematics and stability with RSS-GIS

A GIS-implemented, deterministic approach for the automated spatial evaluation of geometrical and kinematical properties of rock slope terrains is presented. Based on spatially distributed directional information on planar geological fabrics and DEM-derived topographic attribute data, the internal geometry of rock slopes can be characterized on a grid cell basis. For such computations, different approaches for the analysis and regionalization of available structural directional information applicable in specific tectonic settings are demonstrated and implemented in a GIS environment. Simple kinematical testing procedures based on feasibility criteria can be conducted on a pixel basis to determine which failure mechanisms are likely to occur at particular terrain locations. In combination with hydraulic and strength data on geological discontinuities, scenario-based rock slope stability evaluations can be performed. For conceptual investigations on rock slope failure processes, a GIS-based specification tool for a 2-D distinct element code (UDEC) was designed to operate with the GIS-encoded spatially distributed rock slope data. The concepts of the proposed methodology for rock slope hazard assessments are demonstrated at three different test sites in Germany.     

Sea‐level and ocean‐current control on carbonate‐platform growth,Maldives, Indian Ocean

Multichannel high‐resolution seismic and multibeam data were acquired from the Maldives‐isolated carbonate platform in the Indian Ocean for a detailed characterization of the Neogene bank architecture of this edifice. The goal of the research is to decipher the controlling factors of platform evolution, with a special emphasis on sea‐level changes and changes of the oceanic currents. The stacking pattern of Lower to Middle Miocene depositional sequences, with an evolution of a ramp geometry to a flat‐topped platform, reflects variations of accommodation, which here are proposed to be primarily governed by fluctuations of relative sea level. Easterly currents during this stage of bank growth controlled an asymmetric east‐directed progradation of the bank edge. During the late middle Miocene, this system was replaced by a twofold configuration of bank development. Bank growth continued synchronously with partial bank demise and associated sediment‐drift deposition. This turnover is attributed to the onset and/or intensification of the Indian monsoon and related upwelling and occurrence of currents, locally changing environmental conditions and impinging upon the carbonate system. Mega spill over lobes, shaped by reversing currents, formed as large‐scale prograding complexes, which have previously been interpreted as deposits formed during a forced regression. On a regional scale, a complex carbonate‐platform growth can occur, with a coexistence of bank‐margin progradation and aggradation, as well as partial drowning. It is further shown that a downward shift of clinoforms and offlapping geometries in carbonate platforms are not necessarily indicative for a sea‐level driven forced regression. Findings are expected to be applicable to other examples of Cenozoic platforms in the Indo‐Pacific region.     

Assessment of the statistical significance of global changes in the annual river runoff in XXI century due to possible anthropogenic warming of climate

A number of uncertainties of forecasts of changes in the annual runoff depths at global scale, obtained using information on results of integration of 21 IPCC climate models is studied. Following possible errors of these forecasts are calculated: errors of models; differences between main (IPCC) scenarios of emission of greenhouse gases in the atmosphere and resultant changes of global temperatures; mistakes in estimates of average long-term observed values of the runoff depths for the “control” period. Global maps of a “significance index” of forecasted changes in the runoff depths (estimations of changes in the annual runoff depths divided by mean square root values of errors of these estimations) for 2025, 2050, 2075 and 2100 are presented. It is shown that the most significant global changes of the runoff depths (growth in the north of Eastern Siberia, of the Russian Far East, of North America, falling in the “Greater Mediterranean Region”) are predicted for the second quarter of 21st century. Further changes of the runoff amplify only in the Amazon basin (reduction, by 2075). Almost everywhere else (including almost all European territory of Russia, Western Siberia, south of Eastern Siberia and of the Far East) the significance of changes in the runoff depths during 21st century is negligible.     

The theory of spontaneous emission by electrons during their motion along the quantizing magnetic field of a star

The quantum motion of non-relativistic and relativistic electrons in the presence of constant magnetic fields at the surfaces of magnetic stars, magnetic white dwarfs, and pulsars is considered. The quantizing magnetic-field strengths for charged particles with specified energies are determined. The quantum motion of these particles in a plane perpendicular to the magnetic field is accompanied by spontaneous radiation due to electron transitions from higher to lower discrete energy levels, right down to the ground state. In the non-relativistic case, this emission is monochromatic. In the non-relativistic case, various frequencies are emitted, but lie within an order of magnitude of each other. The electron kinetic energy along the magnetic field varies from zero to a maximum value, due to the one-dimensional character of the motion along the field, between each pair of potential barriers corresponding to the discrete energy levels. The results may be relevant to describing gamma-ray flares of pulsars.     

Searches for very high energy gamma rays from blazars with CANGAROO-III telescope in 2005-2009

We have searched for very high energy (VHE) gamma rays from four blazars using the CANGAROO-III imaging atmospheric Cherenkov telescope. We report the results of the observations of H 2356-309, PKS 2155-304, PKS 0537-441, and 3C 279, performed from 2005 to 2009, applying a new analysis to suppress the effects of the position dependence of Cherenkov images in the field of view. No significant VHE gamma ray emission was detected from any of the four blazars. The GeV gamma-ray spectra of these objects were obtained by analyzing Fermi/LAT archival data. Wide range (radio to VHE gamma-ray bands) spectral energy distributions (SEDs) including CANGAROO-III upper limits, GeV gamma-ray spectra, and archival data, even though they are non-simultaneous, are discussed using a one-zone synchrotron self-Compton (SSC) model in combination with a external Compton (EC) radiation. The HBLs (H 2356-309 and PKS 2155-304) can be explained by a simple SSC model, and PKS 0537-441 and 3C 279 are well modeled by a combination of SSC and EC model. We find a consistency with the blazar sequence in terms of strength of magnetic field and component size.     

Radio Emission of Flares and Coronal Mass Ejections

We review recent progress on our understanding of radio emission from solar flares and coronal mass ejections (CMEs) with emphasis on those aspects of the subject that help us address questions about energy release and its properties, the configuration of flare?–?CME source regions, coronal shocks, particle acceleration and transport, and the origin of solar energetic particle (SEP) events. Radio emission from electron beams can provide information about the electron acceleration process, the location of injection of electrons in the corona, and the properties of the ambient coronal structures. Mildly relativistic electrons gyrating in the magnetic fields of flaring loops produce radio emission via the gyrosynchrotron mechanism, which provides constraints on the magnetic field and the properties of energetic electrons. CME detection at radio wavelengths tracks the eruption from its early phase and reveals the participation of a multitude of loops of widely differing scale. Both flares and CMEs can ignite shock waves and radio observations offer the most robust tool to study them. The incorporation of radio data into the study of SEP events reveals that a clear-cut distinction between flare-related and CME-related SEP events is difficult to establish.     

Persistent organic pollutants and histological lesions in Mayan catfish Ariopsis assimilis from the Bay of Chetumal, Mexico

Livers of catfish (Ariopsis assimilis) from the Bay of Chetumal were analyzed for organochlorine compounds and hydrocarbons as part of a study to diagnose the environmental health of the Bay after a catfish mass mortality that occurred in 1996. The presence of histological lesions in several organs of the fish as result of chemical exposure was also evaluated. The concentrations of organic pollutants found in the Bay may be considered high if compared to the levels reported for sites affected by chemical pollution. High prevalences of cellular alteration histopathologies were found in liver, including hepatic tumors. The presence of some lesions may be related statistically to environmental pollution in the Bay, specially with chlorinated compounds.     

TEM study of a special grain boundary in a synthetic K-feldspar bicrystal: Manebach Twin

 A monoclinic KAlSi₃O₈ feldspar Manebach twin boundary was synthesized by diffusion bonding and examined using high-resolution transmission electron microscopy. The sharp (001) twin boundary is straight and free of strain. The boundary width is smaller than d₀₀₁. There is no rigid body shift observed at the twin boundary, and the feldspar structure is arranged symmetrically across (001). The twin boundary structure consists of bridged tetrahedral crankshafts, which are characteristic of the feldspar lattice. The grain boundary structure is in good agreement with the geometrical model of Taylor et al. (1934). The grain boundary composition of K_1/2H_1/2AlSi₃O₈ differs from their model. Received: 13 February 2002 / Accepted: 24 December 2002 Acknowledgements We thank M. Rühle, S. Hutt, J. Mayer, A. Strecker and U. Salzberger at MPI, Stuttgart, for their support and valuable advice in preparing TEM sections of bicrystals.     

Variations in exospheric density at heights near 1100km, derived from satellite orbits

In an earlier paper, values of exospheric density were obtained from the orbit of Echo 2 for the years 1964–1965. The results indicated a semi-annual variation in density by a factor of between 2 and 3, considerably larger than predicted by existing atmospheric models.

These studies have now been extended to the beginning of 1967, using both Echo 2 and Calsphere 1, to show how the density is responding to increasing solar activity. Variations in density during 1964 have been analysed in more detail. The long-term variation associated with the solar cycle and the short-term variations associated with magnetic and solar disturbances agree with the variations expected on the basis of current models. The semi-annual variation is persisting to higher levels of solar activity, and although its amplitude is diminishing the factor of variation was still 1.6 in 1966.