157,963 research outputs found

    Fearless Friday: Taylor Bury

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    This week, SURGE is pleased to feature Taylor Bury ’16 as Gettysburg’s Fearless Leader! Taylor is a senior at Gettysburg College. She is a Biology Major from York, Pennsylvania. She has been involved with Student Senate since her first year on campus, rising through the ranks to serve as its President. [excerpt

    Ideal MHD Ballooning modes, shear flow and the stable continuum

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    There is a well established theory of Ballooning modes in a toroidal plasma. The cornerstone of this is a local eigenvalue lambda on each magnetic surface - which also depends on the ballooning phase angle k. In stationary plasmas lambda(k) is required only near its maximum, but in rotating plasmas its average over k is required. Unfortunately in many case lambda(k) does not exist for some range of k, because the spectrum there contains only a stable continuum. This limits the application of the theory, and raises the important question of whether this "stable interval" gives rise to significant damping. This question is re-examined using a new, simplified, model - which leads to the conclusion that there is no appreciable damping at small shear flow. In particular, therefore, a small shear flow should not affect Ballooning mode stability boundaries

    SAMP, the Simple Application Messaging Protocol: Letting applications talk to each other

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    SAMP, the Simple Application Messaging Protocol, is a hub-based communication standard for the exchange of data and control between participating client applications. It has been developed within the context of the Virtual Observatory with the aim of enabling specialised data analysis tools to cooperate as a loosely integrated suite, and is now in use by many and varied desktop and web-based applications dealing with astronomical data. This paper reviews the requirements and design principles that led to SAMP's specification, provides a high-level description of the protocol, and discusses some of its common and possible future usage patterns, with particular attention to those factors that have aided its success in practice.Comment: 12 pages, 3 figures. Accepted for Virtual Observatory special issue of Astronomy and Computin

    The Mayekawa Lecture: The Way Back to Stability and Growth in the Global Economy

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    This paper was presented at the 2008 International Conference, gFrontiers in Monetary Theory and Policy,h held by the Institute for Monetary and Economic Studies, Bank of Japan, in Tokyo on May 28-29, 2008.

    Generalised Marcus Theory for Multi-Molecular Delocalised Charge Transfer

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    Although Marcus theory is widely used to describe charge transfer in molecular systems, in its usual form it is restricted to transfer from one molecule to another. If a charge is delocalised across multiple donor molecules, this approach requires us to treat the entire donor aggregate as a unified supermolecule, leading to potentially expensive quantum-chemical calculations and making it more difficult to understand how the aggregate components contribute to the overall transfer. Here, we show that it is possible to describe charge transfer between groups of molecules in terms of the properties of the constituent molecules and couplings between them, obviating the need for expensive supermolecular calculations. We use the resulting theory to show that charge delocalisation between molecules in either the donor or acceptor aggregates can enhance the rate of charge transfer through a process we call supertransfer (or suppress it through subtransfer). The rate can also be enhanced above what is possible with a single molecule by judiciously tuning energy levels and reorganisation energies. We also describe bridge-mediated charge transfer between delocalised molecular aggregates. The equations of generalised Marcus theory are in closed form, providing qualitative insight into the impact of delocalisation on charge dynamics in molecular systems
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