Decadal-timescale estuarine geomorphic change under future scenarios of climate and sediment supply

© The Authors, 2009. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Estuaries and Coasts 33 (2010): 15-29, doi:10.1007/s12237-009-9244-y.Future estuarine geomorphic change, in response to climate change, sea-level rise, and watershed sediment supply, may govern ecological function, navigation, and water quality. We estimated geomorphic changes in Suisun Bay, CA, under four scenarios using a tidal-timescale hydrodynamic/sediment transport model. Computational expense and data needs were reduced using the morphological hydrograph concept and the morphological acceleration factor. The four scenarios included (1) present-day conditions; (2) sea-level rise and freshwater flow changes of 2030; (3) sea-level rise and decreased watershed sediment supply of 2030; and (4) sea-level rise, freshwater flow changes, and decreased watershed sediment supply of 2030. Sea-level rise increased water levels thereby reducing wave-induced bottom shear stress and sediment redistribution during the wind-wave season. Decreased watershed sediment supply reduced net deposition within the estuary, while minor changes in freshwater flow timing and magnitude induced the smallest overall effect. In all future scenarios, net deposition in the entire estuary and in the shallowest areas did not keep pace with sea-level rise, suggesting that intertidal and wetland areas may struggle to maintain elevation. Tidal-timescale simulations using future conditions were also used to infer changes in optical depth: though sea-level rise acts to decrease mean light irradiance, decreased suspended-sediment concentrations increase irradiance, yielding small changes in optical depth. The modeling results also assisted with the development of a dimensionless estuarine geomorphic number representing the ratio of potential sediment import forces to sediment export forces; we found the number to be linearly related to relative geomorphic change in Suisun Bay. The methods implemented here are widely applicable to evaluating future scenarios of estuarine change over decadal timescales.This study was supported by the US Geological Survey’s Priority Ecosystems Science program, CALFED Bay/ Delta Program, and the University of California Center for Water Resources

Observation of a structural transition during the low temperature growth of the Si(111)-Pb interface.

The low-temperature Si(111)7 x 7-Pb interface has been investigated using surface X-ray diffraction. The Schottky barrier height of the Pb/Si diode is known to depend on the atomic reconstruction of the interface. We have studied the structure of the evolving interface using X-ray growth oscillations and by interrupting the growth and measuring the specular reflectivity. Both techniques reveal that the film is initially highly disordered with irregular oscillations in the reflected intensity during growth. At a critical coverage of approximately five Pb layers, the whole overlayer crystallizes to a well-ordered Pb(111) structure with subsequent growth being layer-by-layer. Detailed models of the mature interface are consistent with the preservation, after burial, of the Si(111)7 x 7-Pb reconstruction originally formed during growth of the first monolayer. (C) 1999 Elsevier Science B.V. All rights reserved

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The absence of interdiffusion and chemical reaction at the Si(111)-Pb interface makes it an attractive prototypical system for studying metal-semiconductor interface formation. Of particular interest is the fact that the surface reconstruction in the early stages of growth influences the Schottky barrier height of Si(111)-Pb diodes. In this paper we present surface X-ray diffraction studies of the buried interfaces which reveal structural differences which correlate with the known electronic properties. In situ studies of the early stages of growth at 85 K are also presented

OCT3 promoter haplotype is associated with metformin pharmacokinetics in Koreans

Abstract Organic cation transporter 3 (OCT3) is expressed in various organs in humans and plays an important role in the transport of organic cations and drugs including metformin. In this study, we identified genetic variations of the OCT3 promoter and functionally characterized each variant by in vitro assays. Next, the association between the functional haplotype of the OCT3 promoter and pharmacokinetics of metformin was evaluated. In our study population, 7 variations and 2 major haplotypes were identified, of which H2 haplotype yielded a significantly higher luciferase activity than did the wild type. Two variants of H2, c.-1603G > A and c.-1547T > G, yielded significantly lower luciferase activities, whereas the luciferase activity of another variant, c.-29G > A, was significantly higher. Two transcription factors, Sp1 and USF1, were involved in the regulation of OCT3 transcription. Analysis of clinical data revealed that 25 subjects, either homozygous or heterozygous for H2, showed increased AUCinf and Cmax by 17.2% and 15.9%, respectively [P = 0.016 and 0.031, GMR (90% CI) = 1.17 (1.06–1.29) and 1.17 (1.04–1.31), respectively], compared to the 20 subjects in the control group. Our study suggests that an OCT3 promoter haplotype affects the pharmacokinetics of metformin in Koreans as well as the OCT3 transcription rate