Nonlinear soil-structure interaction calculations simulating the SIMQUAKE experiment using STEALTH 2D

Transient, nonlinear soil-structure interaction simulations of an Electric Power Research Institute, SIMQUAKE experiment were performed using the large strain, time domain STEALTH 2D code and a cyclic, kinematically hardening cap soil model. Results from the STEALTH simulations were compared to identical simulations performed with the TRANAL code and indicate relatively good agreement between all the STEALTH and TRANAL calculations. The differences that are seen can probably be attributed to: (1) large (STEALTH) vs. small (TRANAL) strain formulation and/or (2) grid discretization differences

Thermophysical and chemical characterization of charring ablative materials Final report

Thermophysical and chemical properties of charring ablative material

The intersection between the Mid-Atlantic Ridge and the Vema Fracture zone in the North Atlantic

Near 11°N, the Mid-Atlantic Ridge is offset by the Verna Fracture. The hypothesis of sea-floor spreading has suggested that the fracture is a transform fault, and this has been confirmed by the first motion studies of recent earthquakes along the fracture. The fault zone is developed as a deep and narrow east-west trending through, bordered on the south side by a high and steep rocky wall representing an uplifted slice of crust...

On the Correlation of Torque and Luminosity in GX 1+4

Over five years of daily hard X-ray (>20 keV) monitoring of the 2-min accretion-powered pulsar GX 1+4 with the Compton Gamma Ray Observatory/BATSE large-area detectors has found nearly continuous rapid spin-down, interrupted by a bright 200-d spin-up episode. During spin-down, the torque becomes more negative as the luminosity increases (assuming that the 20-60 keV pulsed flux traces bolometric luminosity), the opposite of what is predicted by standard accretion torque theory. No changes in the shape of the 20-100 keV pulsed energy spectrum were detected, so that a very drastic change in the spectrum below 20 keV or the pulsed fraction would be required to make the 20-60 keV pulsed flux a poor luminosity tracer. These are the first observations which flatly contradict standard magnetic disk accretion theory, and they may have important implications for understanding the spin evolution of X-ray binaries, cataclysmic variables, and protostars. We briefly discuss the possibility that GX 1+4 may be accreting from a retrograde disk during spin-down, as previously suggested.Comment: 10 pages including 3 PS figures. To appear in ApJ Letter

Fallout nuclides in Atlantic and Pacific water columns : GEOSECS data

This report contains results of measurements of the fallout radionuclides 90Sr, 137Cs , 239,240Pu , and 241Am in large volume seawater samples collected between 1972 and 1974 in the Atlantic and Pacific as part of Geochemical Ocean Sections (GEOSECS) program. The stations for which data are reported include both the North and South Atlantic oceans and latitudes north of 20° S in the Pacific Ocean. The 90Sr and 137Cs data set has been corrected by a procedure which estimates independently the analytical blank for the laboratory which made the analysis. When the data quality and spacing permit, water column inventory estimates were made for each nuclide over depth intervals appropriate to the nuclide's distribution.Funding was provided by the United States Department of Energy under Contract DE-AC02-EV03563

Contrasts in hydrology between regions of basal deformation and sliding beneath Rutford Ice Stream, West Antarctica, mapped using radar and seismic data

[1] Spatially coincident radar and seismic data collected two weeks apart on Rutford Ice Stream were analyzed to investigate the mechanical and hydrological characteristics of the ice-bed interface. Seismic data allow the differentiation of bed deformation from basal sliding. In radar data, sliding regions are characterised by highly variable permittivity values. We suggest these regions are characterized by small water bodies, possibly a cavity system. In contrast, deforming regions are characterised by consistent, low permittivity, which suggests intimate ice-sediment contact without a distinct interface. However, in deforming regions we identified three bright radar features similar to 50 m wide, consistent in lateral location over distances of 5-10 km up and downstream, and comprised of water less than similar to 0.2 m deep. We interpret these as part of a water evacuation system, most likely canals. Our results emphasise the great potential of radar and seismic techniques in combination to infer basal conditions beneath ice streams

Nanoparticulate nickel sulfides formed in low temperature aqueous solutions

The nature of the nickel sulfides formed in low temperature aqueous solutions is not well-understood. The material has some intrinsic interest to mineralogy, geochemistry and materials science as well as to biogeochemisty, especially as a possible catalyst involved in the origin and early evolution of life. We synthesized Ni sulfide under anoxic conditions at 25 C: (1) chemically, by the addition of 50 mL of 0.1 M NiSO4Æ7H2O to 100 mL of 0.05M Na2SÆ9H2O; (2) electrochemically, with a Ni foil and H2S gas. At pH 6 5, millerite (b-NiS) was produced electrochemically and NiS mixtures, including heazlewoodite (Ni3S2) and polydymite (Ni3S4), were obtained chemically. At pH >11, a- NiS was obtained from the chemical reaction. At pH 6–9, the product produced only two broad peaks (d = ca. 2.7 and 1.8 ) with conventional and synchrotron XRPD which could be assigned to a number of Ni sulfides. It has previously been referred to as ‘‘amorphous NiS’’ Jeong and Manthiram, 2001. Eight SAED reflections were collected which identified the material as godlevskite, orthorhombic NiS. HRTEM shows that the godlevskite particles are ca. 30 nm in diameter and plate-like. SAXS analyses show that the material is 6–8.5 nm thick. Godlevskite is structurally related to makinawite, tetragonal FeS, and is found naturally in similar parageneses-associated with the monosulfide solid solution products of high temperature nickel ores. Mackinawite is the black FeS precipitate from the reaction between Fe(II) and S(-II) in aqueous solution. It appears that, geochemically, godlevskite is the Ni analogue of mackinawite