Decline in Methylmercury in Museum-Preserved Bivalves from San Francisco Bay, California

There are ongoing efforts to manage mercury and nutrient pollution in San Francisco Bay (California, USA), but historical data on biological responses are limited. We used bivalves preserved in formalin or ethanol from museum collections to investigate long-term trends in methylmercury (MeHg) concentrations and carbon and nitrogen isotopic signatures. In the southern reach of the estuary, South Bay, MeHg in the Asian date mussel (Musculista senhousia) significantly declined over the study duration (1970 to 2012). Mean MeHg concentrations were highest (218 ng/g dry weight, dw) in 1975 and declined 3.8-fold (to 57 ng/g dw) by 2012. This decrease corresponded with closure of the New Almaden Mercury Mines and was consistent with previously observed declines in sediment core mercury concentrations. In contrast, across all sites, MeHg in the overbite clam (Potamocorbula amurensis) increased 1.3-fold from 64 ng/g dw before 2000 to 81 ng/g dw during the 2000s and was higher than in M. senhousia. Pearson correlation coefficients of the association between MeHg and δ13C or δ15N provided no evidence that food web alterations explained changing MeHg concentrations. However, isotopic composition shifted temporally. South Bay bivalve δ15N increased from 12‰ in the 1970s to 18‰ in 2012. This increase corresponded with increasing nitrogen loadings from wastewater treatment plants until the late 1980s and increasing phytoplankton biomass from the 1990s to 2012. Similarly, a 3‰ decline in δ13C from 2002 to 2012 may represent greater utilization of planktonic food sources. In a complimentary 90 day laboratory study to validate use of these preserved specimens, preservation had only minor effects (\u3c 0.5‰) on δ13C and δ15N. MeHg increased following preservation but then stabilized. These are the first documented long-term trends in biota MeHg and stable isotopes in this heavily impacted estuary and support the utility of preserved specimens to infer contaminant and biogeochemical trends

A Comparison of Boosted-Discharge Hollow Cathode Lamps and an Inductively Coupled Plasma (ICP) as Excitation Sources in ICP Atomic Fluorescence Spectrometry

Copper, nickel and lead boosted-discharge hollow cathode lamps, run at recommended currents, have been compared with a high-powered inductively coupled plasma (ICP) as excitation sources in atomic fluorescence spectrometry (AFS). A similar comparison was made with a copper lamp run at higher currents. It was found that for lead and nickel, the fluorescence spectra differed in the relative intensities of the transitions observed with the two sources. No evidence was found for a difference in radiances between the two sources when the lamp was overrun. Although the lamps gave rise to lower blank standard deviation values, detection limits were worse because of poorer sensitivity due to the inability of the circular source to illuminate the required atom cell volume in the atomiser. It was concluded that the ICP was the better source, when the criterion is detection limits, but the lamps may be more convenient in some circumstances

IOME, A Toolkit for Distributed and Collaborative Computational Science and Engineering

The internet provides a media rich communications platform enabling communities to share content. Alongside the increased activity in collaborative work, recent developments on workflow tools are now enabling researchers from different disciplines to collaborate by feeding data and results between large multi-disciplinary, optimization problems. Researchers developing computational models require development kits and tools enabling them to provide simulations with a range of methods that facilitate collaboration. This paper presents a unique, multi-purpose tool-kit, enabling researchers to easily develop simulations which may be run as web services and accessed interactively. The development kit is based on a protocol that uses an XML markup called IOME ML, "the Interactive Object Management Environment Markup Language". The paper describes the IOME ML and it's development kit. We illustrate the capabilities of IOME with two case studies. Firstly, a medical image processing application which is wrapped as a web service and accessed through a web browser offering medical professionals image analysis tools. Secondly, a method of collaborative visualisation and computational steering of a tsunami simulation based on a shallow water wave model. The paper concludes with a review of further developments including refinements to the mark up language and the development of a service factory enabling dynamic invocation of published simulations as IOME web service applications

Slicing Strategies for the Generalised Type-2 Mamdani Fuzzy Inferencing System

The final publication is available at Springer via http://dx.doi.org/[insert DOI]".As a three-dimensional object, there are a number of ways of slicing a generalised type-2 fuzzy set. In the context of the Mamdani Fuzzy Inferencing System, this paper concerns three accepted slicing strategies, the vertical slice, the wavy slice, and the horizontal slice or alpha -plane. Two ways of de ning the generalised type-2 fuzzy set, vertical slices and wavy slices, are presented. Fuzzi cation and inferencing is presented in terms of vertical slices. After that, the application of all three slicing strategies to defuzzi cation is described, and their strengths and weaknesses assessed

Inelastic Proton Scattering to M_1 States in 12-C, 24-Mg, and 28-Si at 62 MeV

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

Behavior of electron and ion transport in discharges with an internal transport barrier in the DIII-D tokamak

The authors report results of experiments to further determine the underlying physics behind the formation and development of internal transport barriers (ITB) in the DIII-D tokamak. The initial ITB formation occurs when the neutral beam heating power exceeds a threshold value during the early stages of the current ramp in low-density discharges. This region of reduced transport, made accessible by suppression of long-wavelength turbulence by sheared flows, is most evident in the ion temperature and impurity rotation profiles. In some cases, reduced transport is also observed in the electron temperature and density profiles. If the power is near the threshold, the barrier remains stationary and enclosed only a small fraction of the plasma volume. If, however, the power is increased, the transport barrier expands to encompass a larger fraction of the plasma volume. The dynamic behavior of the transport barrier during the growth phase exhibits rapid transport events that are associated with both broadening of the profiles and reductions in turbulence and associated transport. In some, but not all, cases, these events are correlated with the safety factor q passing through integer values. The final state following this evolution is a plasma exhibiting ion thermal transport at or below neoclassical levels. Typically, the electron thermal transport remains anomalously high. Recent experimental results are reported in which rf electron heating was applied to plasmas with an ion ITB, thereby increasing both the electron and ion transport. Although the results are partially in agreement with the usual {rvec E} x {rvec B} shear suppression hypothesis, the results still leave questions that must be addressed in future experiments

Thermonuclear Reaction Rate of 23Mg(p,gamma)24$Al

Updated stellar rates for the reaction 23Mg(p,gamma)24Al are calculated by using all available experimental information on 24Al excitation energies. Proton and gamma-ray partial widths for astrophysically important resonances are derived from shell model calculations. Correspondences of experimentally observed 24Al levels with shell model states are based on application of the isobaric multiplet mass equation. Our new rates suggest that the 23Mg(p,gamma)24Al reaction influences the nucleosynthesis in the mass A>20 region during thermonuclear runaways on massive white dwarfs.Comment: 13 pages (uses Revtex) including 3 postscript figures (uses epsfig.sty), accepted for publication in Phys. Rev.

Predictors of drinking and functional outcomes for men and women following inpatient alcohol treatment

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106952/1/ajad12098.pd