Description: Terrestrial water isotope records preserve a history of hydrological cycling that is influenced by past climate and surface topography. δ18O and δD records from authigenic minerals of the western United States display a long-term increase during the Neogene in the vicinity of the Sierra Nevada and the central Rocky Mountains (Rockies), but a smaller increase or decrease in the northern Great Basin. Interpretations of these isotopic trends require quantitative estimates of the influence of climatic and environmental changes on δ18O and δD of soil water. Here we use a coupled atmosphere-land model with water-isotopologue tracking capabilities, ECHAM5-JSBACH-wiso, to simulate precipitation and δ18O responses to elevation-independent changes in Neogene geography, equator to pole temperature gradient (EPGRAD), grassland expansion, and tropical Pacific sea surface temperatures. Both precipitation and soil water δ18O (δ18Osw) respond strongly to Neogene strengthening of the EPGRAD, but weakly to other forcings. An increase in EPGRAD leads to significant drying and 18O enrichment (3‰–5‰) of soil water over the northern Sierra Nevada and central Rockies as a result of Hadley circulation strengthening and enhanced coastal subtropical subsidence. These large-scale circulation changes reduce inland moisture transport from the Pacific Ocean and Gulf of Mexico. Our simulated δ18Osw responses could explain 50%–100% of the proxy δ18O increases over the Sierra Nevada and central Rockies, suggesting that climate change rather than surface subsidence may have been the dominant climate signal in δ18O records in these regions. On the contrary, δ18O responses to climate changes are small in the Great Basin, indicating that the observed δ18O increase over this region was likely a direct response to surface subsidence with elevation losses of 1–1.5 km. Adding this elevation loss to current Great Basin elevations reveals the former existence of a uniformly high plateau extending from the Sierra Nevada to the central Rockies prior to Neogene extension. This revised elevation history brings Neogene δ18O and δD paleoaltimetry of the western United States in accordance with independent lines of structural evidence and early Cenozoic elevation reconstructions.

Description: Variations in oxygen isotope ratios (δ18O) measured from modern precipitation and geologic archives provide a promising tool for understanding modern and past climate dynamics and tracking elevation changes over geologic time. In areas of extreme topography, such as the Tibetan Plateau, the interpretation of δ18O has proven challenging. This study investigates the climate controls on temporal (daily and 6 h intervals) and spatial variations in present-day precipitation δ18O (δ18Op) across the Tibetan Plateau using a 30 year record produced from the European Centre/Hamburg ECHAM5-wiso global atmospheric general circulation model (GCM). Results indicate spatial and temporal agreement between model-predicted δ18Op and observations. Large daily δ18Op variations of 25 to +5‰ occur over the Tibetan Plateau throughout the 30 simulation years, along with interannual δ18Op variations of ~2‰. Analysis of extreme daily δ18Op indicates that extreme low values coincide with extreme highs in precipitation amount. During the summer, monsoon vapor transport from the north and southwest of the plateau generally corresponds with high δ18Op, whereas vapor transport from the Indian Ocean corresponds with average to low δ18Op. Thus, vapor source variations are one important cause of the spatial-temporal differences in δ18Op. Comparison of GCM and Rayleigh Distillation Model (RDM)-predicted δ18Op indicates a modest agreement for the Himalaya region (averaged over 86°–94°E), confirming application of the simpler RDM approach for estimating δ18Op lapse rates across Himalaya.

Description: Nonparametric comparison of survival functions is one of the most commonly required task in failure time studies such as clinical trials, and for this, many procedures have been developed under various situations. This paper considers a situation that often occurs in practice but has not been discussed much: the comparison based on interval-censored data in the presence of unequal censoring. That is, one observes only interval-censored data, and the distributions of or the mechanisms behind censoring variables may depend on treatments and thus be different for the subjects in different treatment groups. For the problem, a test procedure is developed that takes into account the difference between the distributions of the censoring variables, and the asymptotic normality of the test statistics is given. For the assessment of the performance of the procedure, a simulation study is conducted and suggests that it works well for practical situations. An illustrative example is provided. Copyright © 2017 John Wiley & Sons, Ltd.

Description: Author(s): Tingwei Chen, Ya-nan Hao, Fan Jin, Min Wei, Jin Feng, Ran Jia, Zhijun Yi, Michael Rohlfing, Chengbu Liu, and Yuchen Ma Defects play crucial roles in the photonic and chemical activities of TiO 2 . The origin of the deep band-gap defect state S b g in the rutile TiO 2 (110) surface has remained controversial for quite a long time. Using many-body Green's function theory, we believe that S b g can be attributed only to σ bond... [Phys. Rev. B 98, 205135] Published Mon Nov 19, 2018

Description: Evaluation of in vitro and in vivo biocompatibility of a myo-inositol hexakisphosphate gelated polyaniline hydrogel in a rat model Scientific Reports, Published online: 13 April 2016; doi:10.1038/srep23931