Gujba: A new Bencubbin-like meteorite fall from Nigeria

Gujba is a new Bencubbin-like meteorite fall enriched in N-15 and consisting (in vol.%) of 41% metal nodules, 20% large light-colored silicate nodules and 39% dark-colored, C- and silicate-rich matrix

The influence of sea level rise and changes in fringing reef morphology on gradients in alongshore sediment transport

Climate-change-induced alterations to coral reef ecosystems, in combination with sea level rise, have the potential to significantly alter wave dissipation across reefs, leading to shifts in alongshore sediment transport gradients and alterations to tropical coastlines. We used Delft3D to model schematized profiles of two reef flat widths based on the south Molokai, Hawaii coast. Simulated anthropogenic modifications include incremental degradation of the reef structure as well as sea level rise. Our findings indicate that sea level rise has a greater relative effect on wave energy flux and alongshore sediment transport over a wide flat, whereas both reef degradation and sea level rise exert similar influence over a narrow flat. These results suggest reefs that vary in width alongshore are more likely to experience changes in alongshore sediment transport gradients, and therefore shifts in shoreline erosion and accretion patterns, than more uniform reef systems. Key Points Non-uniform reef flat width leads to gradients in alongshore sediment transport Shoreline change is most likely where reef degradation outpaces sea-level rise Rates of shoreline change potentially linked to coral reef healt

Observational diagnostics of gas in protoplanetary disks

Protoplanetary disks are composed primarily of gas (99% of the mass). Nevertheless, relatively few observational constraints exist for the gas in disks. In this review, I discuss several observational diagnostics in the UV, optical, near-IR, mid-IR, and (sub)-mm wavelengths that have been employed to study the gas in the disks of young stellar objects. I concentrate in diagnostics that probe the inner 20 AU of the disk, the region where planets are expected to form. I discuss the potential and limitations of each gas tracer and present prospects for future research.Comment: Review written for the proceedings of the conference "Origin and Evolution of Planets 2008", Ascona, Switzerland, June 29 - July 4, 2008. Date manuscript: October 2008. 17 Pages, 6 graphics, 134 reference

The stable isotopic composition of carbon, nitrogen and hydrogen in some Yamato meteorites

Three carbonaceous chondrites from the Yamato Mountains (Y-790112,Y-790032,Y-790003) were studied by stepwise combustion in order to distinguish different components of carbon, nitrogen and hydrogen on the basis of release temperature and isotopic composition

Random walks for interactive organ segmentation in two and three dimensions: Implementation and validation

Abstract. A new approach to interactive segmentation based on random walks was recently introduced that shows promise for allowing physicians more flexibility to segment arbitrary objects in an image. This report has two goals: To introduce a novel computational method for applying the random walker algorithm in 2D/3D using the Graphics Processing Unit (GPU) and to provide quantitative validation studies of this algorithm relative to different targets, imaging modalities and interaction strategies.