Uplift rate of Kitadaito Jima Island on the lithospheric forebulge of the Philippine Sea Plate

Abstract Estimates of uplift rates for lithospheric forebulges are needed to understand exact plate motions at plate convergence zones and to delineate the fate of coral reefs atop the forebulges. A carbonate island on a lithospheric forebulge can provide excellent materials for estimating uplift rate because carbonate sediments can be dated and their paleo-water depth determined. We estimated the uplift rate of Kitadaito Jima Island, a carbonate island on the lithospheric forebulge of the Philippine Sea Plate that is subducting beneath the Eurasian Plate. Marine skeletal sands containing pebble-sized bioclasts and filling the concavity of an intertidal erosional notch at an elevation of ~ 71 m were found near the top of this island. Strontium isotope ages ranging from 1.78 to 2.01 Ma with an average of 1.89 Ma (standard deviation = 0.07 Ma) were obtained from these deposits. As global sea level at 1.89 Ma was ~ 21 m lower than the present, the mean uplift rate was estimated at ~ 49 m/million years (Myr) with a compounded uncertainty of ± 2.6 m/Myr. This rate is comparable to, or up to ~ 140 m/Myr less than, rates reported from other Indo-Pacific carbonate islands in similar tectonic settings. This study illustrates how contemporary Sr isotope age models and careful considerations of limestone sample depositional depths can yield more accurate and precise uplift rates of modern forearc bulges than possible in many older studies

Evaluating Prion Models Based on Comprehensive Mutation Data of Mouse PrP

SummaryThe structural details of the essential entity of prion disease, fibril prion protein (PrPSc), are still elusive despite the large body of evidence supporting the prion hypothesis. Five major working models of PrPSc structure, which are not compatible with each other, have been proposed. However, no systematic evaluation has been performed on those models. We devised a method that combined systematic point mutation with threading on knowledge-based amino acid potentials. A comprehensive mutation experiment was performed on mouse prion protein, and the PrPSc conversion efficiency of each mutant was examined. The models were evaluated based on the mutation data by using the threading method. Although the data turned out to be rather more consistent with the models that assumed a conversion of the N-terminal region of core PrP into a β helix than with others, substantial modifications were also required to further improve the current model based on recent experimental results

Plasma Diagnostics Required for a Heliotron-Type DEMO Reactor

The plasma diagnostics required for a heliotron-type DEMO reactor are discussed in terms of real-time burn control and safe operation of the machine. The minimum diagnostic set having the smallest footprint are essential in DEMO. Neutron transport calculation suggests that the diagnostic components used in existing experiments will deteriorate immediately in a DEMO reactor hall if they are not protected by a neutron shield. Neutron energy spectrometry is a promising diagnostic that is expected to play an important role in diagnosing DEMO plasmas, providing a fusion energy output, fuel ion temperature, ratio of deuteron density nD to triton density nT, and velocity distribution of confined α particles