Kinetics of the Photoreduction of \u3cem\u3ep\u3c/em\u3e-nitrobenzoic Acid on Ag and AgxAu1-x Nanoparticle Films

A recent strategy to increase the efficiency of photovoltaic and photoemissive devices has been to include metal nanolayers in contact with an organic layer inside these devices. Metal nanoparticles (especially Ag and Au) are known to catalyze photoreactions of organic molecules on their surfaces. The reactivity of organics at nanometal surfaces has implications for device lifetimes; therefore, it is important to understand how nanoparticle size and composition influence reaction rates. The photoreduction of p-nitrobenzoate (PNBA) to p,p’-azodibenzoate (PPADBA) on Ag nanoparticles is an excellent model system for studying such reactions. We have measured the reaction rate of PNBA to PPADBA on Ag and Au based nanoparticle surfaces using surface-enhanced Raman spectroscopy (SERS). SERS is a highly sensitive spectroscopic tool, which provides molecular fingerprints that can be used to identify molecular species present on metal nanoparticle surfaces. These surfaces are made from layers from Ag and AgxAu1-x alloy nanoparticles with diameters ranging from 50-80 nm

University Finds Windows HPC Server Matches Linux in Validated SPEC Benchmarks

Case study: Indiana University (IU) ran the first published, validated high-performance computing (HPC) benchmarks on Windows HPC Server and Linux, and found the two perform about the same across applications and cluster sizes. But Windows HPC Server opens new possibilities when it comes to market options and use beyond the traditional science uses of HPC. IU is planning to implement Windows HPC Server in its overall HPC strategy

Co-Evolving Expertise in Environmental Policy Debates: Rethinking Values and Participants through an Ecological Model of Rhetoric

Environmental policy controversies reflect a struggle between “subjective” (human) and “objective” (scientific) knowledge, which a more rhetorical science could reconcile. I draw from actor network theory and rhetorical identification to suggest a model of ecological rhetoric, which I apply to two science policy projects: ecosystem service markets and adaptive management

Feasibility of mitigating physical disturbances to eelgrass in northern Casco Bay: Impacts and Options

This report has been prepared in response to a requirement set forth in the Maine Department of Environmental Protection’s permit issued to the Maine Department of Inland Fisheries and Wildlife for construction of an all-tide boat launch facility on Merepoint Neck, Brunswick, Maine that calls for the development of a feasibility guide of mitigation options in northern Casco Bay for physical disturbance impacts to eelgrass, Zostera marina, occurring there

A GPU-Computing Approach to Solar Stokes Profile Inversion

We present a new computational approach to the inversion of solar photospheric Stokes polarization profiles, under the Milne-Eddington model, for vector magnetography. Our code, named GENESIS (GENEtic Stokes Inversion Strategy), employs multi-threaded parallel-processing techniques to harness the computing power of graphics processing units GPUs, along with algorithms designed to exploit the inherent parallelism of the Stokes inversion problem. Using a genetic algorithm (GA) engineered specifically for use with a GPU, we produce full-disc maps of the photospheric vector magnetic field from polarized spectral line observations recorded by the Synoptic Optical Long-term Investigations of the Sun (SOLIS) Vector Spectromagnetograph (VSM) instrument. We show the advantages of pairing a population-parallel genetic algorithm with data-parallel GPU-computing techniques, and present an overview of the Stokes inversion problem, including a description of our adaptation to the GPU-computing paradigm. Full-disc vector magnetograms derived by this method are shown, using SOLIS/VSM data observed on 2008 March 28 at 15:45 UT