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Picosecond Dynamics of Free-Carrier Populations, Space-Charge Fields, and Photorefractive Nonlinearities in Zincblende Semiconductors

Picosecond Dynamics of Free-Carrier Populations, Space-Charge Fields, and Photorefractive Nonlinearities in Zincblende Semiconductors

Date: August 1999
Creator: Stark, Thomas S.
Description: Generally, nonlinear optics studies investigate optically-induced changes in refraction or absorption, and their application to spectroscopy or device fabrication. The photorefractive effect is a nonlinear optical effect that occurs in solids, where transport of an optically-induced free-carrier population results in an internal space-charge field, which produces an index change via the linear electrooptic effect. The photorefractive effect has been widely studied for a variety of materials and device applications, mainly because it allows large index changes to be generated with laser beams having only a few milliwatts of average power.Compound semiconductors are important photorefractive materials because they offer a near-infrared optical response, and because their carrier transport properties allow the index change to be generated quickly and efficiently. While many researchers have attempted to measure the fundamental temporal dynamics of the photorefractive effect in semiconductors using continuous-wave, nanosecond- and picosecond-pulsed laser beams, these investigations have been unsuccessful. However, studies with this goal are of clear relevance because they provide information about the fundamental physical processes that produce this effect, as well as the material's speed and efficiency limitations for device applications.In this dissertation, for the first time, we time-resolve the temporal dynamics of the photorefractive nonlinearities in two zincblende semiconductors, ...
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Explorations with polycarbocyclic cage compounds

Explorations with polycarbocyclic cage compounds

Date: August 1999
Creator: Chong, Hyun-Soon
Description: A variety of novel cage-functionalized pyridyl containing crown ethers have been prepared for use in selective alkali metal complexation studies. A highly preorganized, cage-functionalized cryptand also has been designed and has been synthesized for use as a selective Li+ complexant. The alkali metal picrate extraction profiles of these cage-functionalized crown ethers also have been studied. Novel cage-functionalized diazacrown ethers have been prepared for selective alkali metal complexation studies. Alkali metal picrate extraction experiments have been performed by using this new class of synthetic ionophores to investigate the effects of cage-annulation and the influence of N-pivot lariat sidearms upon their resulting complexation properties. Novel pyridyl containing calix[4]arene receptors were prepared. Analysis of their respective 1H NMR and 13C NMR spectra suggests that calix[4]arene moieties in the ligand occupy the cone conformation. The complexation properties of these host molecules were estimated by performing a series of alkali metal picrate extraction experiments. An optically active cage-functionalized crown ether which contains a binaphthyl moiety as the chiral unit was prepared. The ability of the resulting optically active crown ether to distinguish between enantiomers of guest ammonium ions (i.e., phenylethylamonium and phenylglycinate salts) in transport experiments was investigated. Hexacyclo[11.2.1.02,12.05,10.05,15.010,14]hexadeca-6,8-diene-4,11-dione was prepared from hexacyclo[7.4.2.01,9.03,7.04,14.06,15] pentadeca-10,12-diene-2,8-dione. Unanticipated ...
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"Marvelous Accidents": The Concerto for Prepared Piano and Chamber Orchestra of John Cage

"Marvelous Accidents": The Concerto for Prepared Piano and Chamber Orchestra of John Cage

Date: December 1999
Creator: Boutwell, Brett N.
Description: John Cage’s Concerto for Prepared Piano and Chamber Orchestra (1950-51) holds a unique position within the composer’s oeuvre as the first work based in part on chance-derived compositional procedures. Cage entered into such practice gradually, incrementally abandoning subjective taste and personal expression through the course of the work. Drawing from the philosophical framework provided by Cage’s "Lecture on Nothing" (1950) and "Lecture on Something" (c. 1951-52), this thesis explores the aesthetic foundations of the concerto and examines Cage’s compositional methodology throughout its three movements. Special attention is paid to the procedure underlying the first movement, whose analysis is based largely on the composer’s manuscript materials for the work.
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Arctic Climate Impact Science — An Update Since ACIA

Arctic Climate Impact Science — An Update Since ACIA

Date: April 2008
Creator: WWF International Arctic Programme.
Description: The study found that change was occuring in all Arctic systems, impacting on the atmosphere and the oceans, sea ice and ice sheets, snow and permafrost, as well as species and populations, food webs, ecosystems and human societies.
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Climate Change in Indonesia Implications for Humans and Nature

Climate Change in Indonesia Implications for Humans and Nature

Date: November 2004
Creator: Case, Michael
Description: The report highlights that annual rainfall in the world’s fourth most populous nation is already down by 2 to 3 per cent, and the seasons are changing.
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G8 Climate Scorecards

G8 Climate Scorecards

Date: July 2009
Creator: Dr. Höhne, Niklas; Eisbrenner k. Katja; Hagemann, Markus & Moltmann, Sara
Description: The report concludes with a global cumulative GHG emission cap for the period from 2010 till 2050. It outlines mid-term and long-term cumulative emission allowances for key countries under the three equity approaches and trajectories for these countries to keep global warming below 2 degrees Celsius. The objective of the report is to initiate a constructive debate among and foster long-term commitments of the parties while moving towards a fair, ambitious and binding Copenhagen agreement.
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New Mexico Climate Change Advisory Group Final Report

New Mexico Climate Change Advisory Group Final Report

Date: December 2006
Creator: New Mexico Climate Change Advisory Group
Description: Recognizing the profound implications that global warming and climate variation could have on the economy, environment and quality of life in the Southwest, New Mexico Governor Bill Richardson signed Executive Order 05-33 on June 5th, 2005, establishing the New Mexico Climate Change Advisory Group. The Governor directed the CCAG to prepare a report that includes a projection of the State's future GHG emissions and policy recommendations for reducing New Mexico's total greenhouse gas emissions to 2000 levels by the year 2012, 10 percent below 2000 levels by 2020 and 75 percent by 2050.
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Fast Facts: Climate Change and UNDP

Fast Facts: Climate Change and UNDP

Date: October 2009
Creator: United Nations Environment Programme
Description: Making poverty history and tackling climate change go hand-in-hand because receding forests, changing rainfall patterns and rising sea levels trap people in hardship and undermine their future. Studies in Ethiopia show that children exposed to drought in early childhood are 36 percent more likely to be malnourished five years later.
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Montana Climate Change Action Plan: Final Report of the Governor’s Climate Change Advisory Committee

Montana Climate Change Action Plan: Final Report of the Governor’s Climate Change Advisory Committee

Date: November 2007
Creator: Montana.Governor's Climate Change Advisory Committee
Description: Report of the Governor’s Climate Change Advisory Committee, managed by the Montana Department of Environmental Quality and facilitated by the Center for Climate Strategies. It provides 54 policy recommendations help reduce the state’s emissions of green house gases to 1990 levels by the year 2020. Most will have additional benefits, including reduced reliance on imported fossil fuels, reduction in air pollution, increased opportunity for Montana agriculture to provide renewable fuels, healthier forests, and the opportunity for the state to be a leader in developing new technologies.
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Night of no Exile

Night of no Exile

Date: August 1999
Creator: Jones, Marie C.
Description: Night of no Exile is a collection of poems preceded by a critical article entitled "‘Exile seems both a blessing and a curse': A Blissful Reading of Li-Young Lee's Poetry." That article discusses Lee's quest to achieve communication, truth, and transcendence through poetic language and concludes that he finally reaches his goal through a leap from narrative poetry to lyricism. The "exile" alluded to in the title of the article is not only geographic, but also interioran exile due to the natural limitations of all languages, and which can be bridged only in linguistic ways. Lee's solution to that problem (lyricism) turns his poetry into what Roland Barthes would call "a text of bliss," a text that manages to deeply destabilize language, while simultaneously achieving a new kind of meaning. In the main body of the manuscript, the first section contains short love lyrics. The second section, "Night of no Exile," is an attempt at the demanding genre of the longer lyric poem. The third section uses short lyrics to explore various topics, such as discovering one's identity, friendship and solidarity between women, family history, and childhood memories. Finally, the last section includes poems, four of them longer, attempting to ...
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