Application of a relativistic accretion disc model to X-ray spectra of LMC X-1 and GRO J1655-40

We present a general relativistic accretion disc model and its application to the soft-state X-ray spectra of black hole binaries. The model assumes a flat, optically thick disc around a rotating Kerr black hole. The disc locally radiates away the dissipated energy as a blackbody. Special and general relativistic effects influencing photons emitted by the disc are taken into account. The emerging spectrum, as seen by a distant observer, is parametrized by the black hole mass and spin, the accretion rate, the disc inclination angle and the inner disc radius.
We fit the ASCA soft-state X-ray spectra of LMC X-1 and GRO J1655-40 by this model. We find that, having additional limits on the black hole mass and inclination angle from optical/UV observations, we can constrain the black hole spin from X-ray data. In LMC X-1 the constraint is weak, and we can only rule out the maximally rotating black hole. In GRO J1655-40 we can limit the spin much better, and we find 0.68 a 0.88 . Accretion discs in both sources are radiation-pressure dominated. We do not find Compton reflection features in the spectra of any of these objects.     

Rock fragment distributions and regolith evolution in the Ouachita Mountains,Arkansas, USA

Rock fragments in the regolith are a persistent property that reflects the combined influences of geologic controls, erosion, deposition, bioturbation, and weathering. The distribution of rock fragments in regoliths of the Ouachita Mountains, Arkansas, shows that sandstone fragments are common in all layers, even if sandstone is absent in parent material. Shale and sandstone fragments are produced at the bedrock weathering front, but the shale weathers rapidly and intact fragments are rare in the solum. Sandstone is weathered from ridgetop outcrops and transported downslope. Some of these fragments are moved downward, by faunalturbation and by transport into pits associated with rotting tree stumps. Upward movement by treethrow is common, resulting in a net concentration of rocks near the surface. However, the highest fragment concentrations are in the lower regolith, indicating active production at the weathering front. The regolith is a dynamic feature, reflecting the influences of vertical and horizontal processes, of active weathering at the bedrock interface, and of surficial sediment movements. The role of trees in redistributing rock fragments suggests that significant regolith mixing occurs over time scales associated with forest vegetation communities, and that forest soils have likely been extensively mixed within Holocene and historic time. Copyright © 2005 John Wiley & Sons, Ltd.     

Comparison of vitrified and unvitrified Eocene woody tissues by TMAH thermochemolysis – implications for the early stages of the formation of vitrinite

Samples of vitrified and unvitrified Eocene woody plant tissues collected from the Fossil Forest site, Geodetic Hills, Axel Heiberg Island, have been characterized by TMAH thermochemolysis. All samples are gymnosperm-derived, are of very low maturity and all share the same post-depositional geologic history. Differences in the distributions of products observed from vitrified and unvitrified samples suggest that vitrification of woody tissue is associated with modification of the lignin C3 side chain, following loss of all or most of the carbohydrate present in the precursor woody tissues. The key driver of vitrification appears to be physical compression of the tissue following biological removal of cellulosic materials.     

Achieving sub electron noise in CCD systems by means of digital filtering techniques that lower 1/f pixel correlated noise

Scientific CCDs designed in thick high resistivity silicon (Si) are excellent detectors for astronomy, high energy and nuclear physics, and instrumentation. Many applications can benefit from CCDs ultra low noise readout systems. The present work shows how sub electron noise CCD images can be achieved using digital signal processing techniques. These techniques allow 0.4 electrons of noise at readout bandwidths of up to 10?Kpixels per second while keeping the full CCD spatial resolution and signal dynamic range.     

Evaluation of a Movie Theater Advertisement Campaign to Promote Behaviors that Prevent Spread of Aquatic Invasive Species

One of the primary causes of the spread of aquatic invasive species (AIS) is boaters and anglers who move between bodies of water. Engaging with recreational boaters and anglers to encourage preventative behaviors is crucial for managing the spread of AIS. The use of cinema advertising for disseminating pro-environmental messages is a relatively novel and understudied outreach strategy. To explore this approach, an AIS-related public service announcement was placed in the preshow advertising at a movie theater in north central Wisconsin. Movie patrons were surveyed as they left the theater to determine demographic, AIS awareness, advertising exposure, and recall information. The results of this study suggest movie theater advertising is a potentially efficacious medium for pro-environmental outreach efforts.     

What dynamics drive future wind scenarios for coastal upwelling off Peru and Chile?

The dynamics of the Peru–Chile upwelling system (PCUS) are primarily driven by alongshore wind stress and curl, like in other eastern boundary upwelling systems. Previous studies have suggested that upwelling-favorable winds would increase under climate change, due to an enhancement of the thermally-driven cross-shore pressure gradient. Using an atmospheric model on a stretched grid with increased horizontal resolution in the PCUS, a dynamical downscaling of climate scenarios from a global coupled general circulation model (CGCM) is performed to investigate the processes leading to sea-surface wind changes. Downscaled winds associated with present climate show reasonably good agreement with climatological observations. Downscaled winds under climate change show a strengthening off central Chile south of 35°S (at 30°S–35°S) in austral summer (winter) and a weakening elsewhere. An alongshore momentum balance shows that the wind slowdown (strengthening) off Peru and northern Chile (off central Chile) is associated with a decrease (an increase) in the alongshore pressure gradient. Whereas the strengthening off Chile is likely due to the poleward displacement and intensification of the South Pacific Anticyclone, the slowdown off Peru may be associated with increased precipitation over the tropics and associated convective anomalies, as suggested by a vorticity budget analysis. On the other hand, an increase in the land–sea temperature difference is not found to drive similar changes in the cross-shore pressure gradient. Results from another atmospheric model with distinct CGCM forcing and climate scenarios suggest that projected wind changes off Peru are sensitive to concurrent changes in sea surface temperature and rainfall.     

Patterns of Surf Smelt, Hypomesus pretiosus, Intertidal Spawning Habitat Use in Puget Sound, Washington State

Surf smelt Hypomesus pretiosus are an important part of the Salish Sea food web and obligate beach spawners, yet little is known about the spatiotemporal distribution of spawning and beach characteristics related to spawning success. We counted smelt eggs at 51 sites around Camano Island, Puget Sound, Washington every 2?weeks for 1?year and at 13 of those 51 sites each month in the following year. At each site, we measured beach characteristics hypothesized to affect spawning habitat suitability as measured by egg abundance and mortality. Eggs were collected at 45 sites and pooled by month for analyses. Few sites (N?=?10, 19.6?%) contributed 87?% of total eggs and 89?% of all live eggs collected. Mean total egg counts at sites were higher (p?<?0.019) in Jul?CSep (1,790.7, SE?=?829.5) than in Jan?CMar (26.1, SE?=?10.2). Principal component and regression analyses suggested that aspect, fetch, solar radiation, and beach temperature predicted egg abundance but not mortality. Because a small proportion of sites appear to support most spawning activity, a conclusion consistent with year?2 egg counts, impacts to relatively few beaches could greatly affect surf smelt production.     

Subsidence Analysis and Burial History of the Late Carboniferous to Early Jurassic Soutpansberg Basin, Limpopo Province, South Africa

The subsidence history of the Soutpansberg Basin was reconstructed by a tectonic subsidence analysis coupled with backstripping calculations based on data of newly interpreted sequence boundaries. Furthermore,burial and time plots were constructed in order to understand the burial and thermal history of the basin. Input data were based on facies,lithostratigraphic models and tectonic interpretations. The studied succession is up to 1000 m and is underlain by the Achaean Limpopo Mobile Belt. The subsidence within the basin supports the primary graben system which must have been centred within the present basins,and later became a region of faulting. The subsidence and burial history curves suggests two phases of rapid subsidence during the Early-Late Permian(300–230 Ma) and Middle Triassic(215–230 Ma). The areas of greater extension subsided more rapidly during these intervals. Two slow subsidence phases are observed during the Late Triassic(215–198 Ma) and Early Jurassic(198–100 Ma). These intervals represent the post-rift thermal subsidence and are interpreted as slow flexural subsidence. Based on these observations on the subsidence curves,it is possible to infer that the first stage of positive inflexion(300 Ma) is therefore recognised as the first stage of the Soutpansberg Basin formation.     

Shear Strength Development with Burial in Eel River Margin Slope Sediments

As part of the STRATAFORM project, a series of cores were obtained from the Eel River Margin area of Eureka, California. The geotechnical analysis of intact specimens and of reconstituted samples provides some insight on the development of shear strength with burial. The results show the effect of bioturbation in the early part of the lifetime of a sediment. SEDCON tests were used to proposed various relationships which help predict the changes in density, liquidity index, and strength as a function of depth. These relationships are found useful from near the water sediment-interface down to a depth of at least 400 m in the sediment column.