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1997

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Modeling And Simulation Support For Parallel Algorithms In A High-Speed Network, Dustin E. Yates Dec 1997

Modeling And Simulation Support For Parallel Algorithms In A High-Speed Network, Dustin E. Yates

Theses and Dissertations

This thesis investigates the ability of a simulation model to compare and contrast parallel processing algorithms in a high-speed network. The model extends existing modeling, analysis, and comparison of parallel algorithms by providing graphics based components that facilitate the measurement of system resources. Simulation components are based on the Myrinet local area network standard. The models provide seven different topologies to contrast the performance of five variations of Fast Fourier Transform (FFT) algorithms. Furthermore, the models were implemented using a commercially developed product that facilitates the testing of additional topologies and the investigation of hardware variations. Accurate comparisons are statistically …

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Spontaneous Emission In Microcavity Lasers, Dustin Philip Ziegler Dec 1997

Spontaneous Emission In Microcavity Lasers, Dustin Philip Ziegler

Theses and Dissertations

An understanding of spontaneous emission processes within microcavities is crucial in addressing the need to make tomorrow's microlasers more efficient. One approach to improving the device efficiency is to reduce the threshold input energy at which lasing begins to occur. It has been suggested that the threshold in a microcavity laser can be decreased by increasing the fraction of spontaneous emission into the lasing mode, this can be accomplished by preferentially coupling the gain medium of the laser to the electromagnetic cavity mode of interest. It therefore becomes necessary to understand the mechanism by which this coupling takes place. This …

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The Rational Resolution Analysis: A Generalization Of Multi-Resolution Analyses With Application To To The Specific Emitter Identification Problem, Bruce P. Anderson Dec 1997

The Rational Resolution Analysis: A Generalization Of Multi-Resolution Analyses With Application To To The Specific Emitter Identification Problem, Bruce P. Anderson

Theses and Dissertations

The rational resolution analysis RRA is introduced and developed as a generalization of the integer, dilation multiresolution analyses MRA developed by Mallat and Meyer. Rational dilation factors are achieved by relaxing the condition on MRAs that successive approximation spaces be embedded. Conditions for perfect reconstruction are discussed and it is shown that perfect reconstruction is possible with specific constraints on the scaling function the scaling filter must have its roots on the unit circle. Furthermore, the required arrangement of the roots indicate the scaling function must be derived from a B-spline of some degree. It is proven the only compactly …

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Reactive Quantum Scattering In Two Dimensions, Roy S. Calfas Dec 1997

Reactive Quantum Scattering In Two Dimensions, Roy S. Calfas

Theses and Dissertations

In an effort to develop a more efficient time dependent approach for calculating scattering matrix elements, absorbing boundary conditions are combined together with the channel packet method. As an introduction to scattering, scattering matrix elements are presented for a one-dimensional square well and a one-dimensional potential consisting of a Gaussian well with symmetric Gaussian barriers. Next, the combination of the channel packet method together with absorbing boundary conditions yields an order of magnitude savings in the time necessary to compute the correlation function for the collinear H+H

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Optimal Pulsed Pumping For Remediation Of Aquifers When Sorption Is Rate-Limited, Lawrence J. Schmitt Dec 1997

Optimal Pulsed Pumping For Remediation Of Aquifers When Sorption Is Rate-Limited, Lawrence J. Schmitt

Theses and Dissertations

A variational optimization technique is developed to acquire an optimal schedule of pulsed pumping operations for use at existing pump-and-treat aquifer remediation sites. The optimization problem is stated as a minimization of a generic management objective functional, constrained by the contaminant transport equations in two-dimensional or three-dimensional flow models which account for rate-limited sorption. The two-dimensional case is fully developed and a first-order rate equation is used to describe the transport of sorbing contaminant. The first variation provides necessary optimality conditions that must be met by any optimal solution, in turn leading to a pulsed pumping schedule of operation. The …

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An Examination Of Multi-Tier Designs For Legacy Data Access, Michael L. Acker Dec 1997

An Examination Of Multi-Tier Designs For Legacy Data Access, Michael L. Acker

Theses and Dissertations

This work examines the application of Java and the Common Object Request Broker Architecture (CORBA) to support access to remote databases via the Internet. The research applies these software technologies to assist an Air Force distance learning provider in improving the capabilities of its World Wide Web-based correspondence system. An analysis of the distance learning provider's operation revealed a strong dependency on a non-collocated legacy relational database. This dependency limits the distance learning provider's future web-based capabilities. A recommendation to improve operation by data replication is proposed, and the implementation details are provided for two alternative test systems that support …

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Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole Dec 1997

Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The emergence of streaming multimedia players provides users with low latency audio and video content over the Internet. Providing high-quality, best-effort, real-time multimedia content requires adaptive delivery schemes that fairly share the available network bandwidth with reliable data protocols such as TCP. This paper proposes a new flow and congestion control scheme, SCP (Streaming Control Protocol) , for real-time streaming of continuous multimedia data across the Internet. The design of SCP arose from several years of experience in building and using adaptive real-time streaming video players. SCP addresses two issues associated with real-time streaming. First, it uses a congestion control …

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An Analysis Of Early Software Reliability Improvement Techniques, John G. Leonard, Ric K. Nordgren Dec 1997

An Analysis Of Early Software Reliability Improvement Techniques, John G. Leonard, Ric K. Nordgren

Theses and Dissertations

This research explores early life cycle software reliability prediction models or techniques to predict the reliability of software prior to writing code, and a method for increasing or improving the reliability of software products early in the development life cycle. Five prediction models and two development techniques are examined. Each model is statically analyzed in terms of availability of data early in the life cycle, ease of data collection, and whether data is currently collected. One model and the two techniques satisfied those requirements and are further analyzed for their ability to predict or improve software reliability. While the researchers …

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An Incompleteness Handling Methodology For Validation Of Bayesian Knowledge Bases, David J. Bawcom Dec 1997

An Incompleteness Handling Methodology For Validation Of Bayesian Knowledge Bases, David J. Bawcom

Theses and Dissertations

The PESKI (Probabilities, Expert Systems, Knowledge, and Inference) system attempts to address some of the problems in expert system design through the use of the Bayesian Knowledge Base (BKB) representation. Knowledge gathered from a domain expert is placed into this framework and inferencing is performed over it. However, by the nature of BKBs, not all knowledge is incorporated, i.e. the representation need not be a complete representation of all combinations and possibilities of the knowledge, as this would be impractical in many real-world systems. Therefore, inherent in such a system is the problem of incomplete knowledge, or spaces within the …

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Developing A Corpus Specific Stoplist Using Quantitative Comparison, Craig N. Berg Dec 1997

Developing A Corpus Specific Stoplist Using Quantitative Comparison, Craig N. Berg

Theses and Dissertations

We have become overwhelmed with electronic information and it seems our situation is not going to improve. It is becoming increasingly common for people to work with information on a daily basis. We seem to spend more and more time looking for information, and it is taking longer because more information is available. This thesis will look at how we can provide faster access to the information we want to find. Today's requirements are closely related to searching for information using queries. At the heart of the query process is the removal of search terms having little or no significance …

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An Investigation Of Plume Rise From Titan Iv Rocket Launches, Joseph D. Brands Dec 1997

An Investigation Of Plume Rise From Titan Iv Rocket Launches, Joseph D. Brands

Theses and Dissertations

Space launches at Cape Canaveral Air Station (CCAS) and Vandenberg Air Force Base (vAFB) produce exhaust ground clouds from the solid rocket boosters and liquid hypergolic fuels containing several toxic substances. In order to estimate the health effects that would be imposed upon the public by scheduled launches, range safety officials rely on the Rocket Exhaust Effluent Diffusion Model to predict ground level concentrations of these substances. A drawback to the REEDM is its underprediction of the initial ground clouds stabilization height. This underprediction causes an overprediction of the ground level toxic substance concentrations. This thesis focused on increasing the …

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Modeling Uptake And Translocation Of Lead (Pb) In Maize For The Purposes Of Phytoextraction, Mark A. Brennan Dec 1997

Modeling Uptake And Translocation Of Lead (Pb) In Maize For The Purposes Of Phytoextraction, Mark A. Brennan

Theses and Dissertations

Phytoextraction is a remediation technology that uses plants to remove heavy metals from soil. This technology has the potential to decrease the costs of remediating contaminated sites by several orders of magnitude compared to traditional technologies. To effectively implement this technology requires an understanding of the plant processes that control uptake and translocation of metals from the soil. Currently these processes are poorly understood, and especially so for Pb. The purpose of this thesis was to gain insights concerning the plant mechanisms that control uptake and translocation of Pb and how these mechanisms interact to control levels of Pb accumulation …

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Visualization And Animation Of A Missile/Target Encounter, Jeffrey T. Bush Dec 1997

Visualization And Animation Of A Missile/Target Encounter, Jeffrey T. Bush

Theses and Dissertations

Existing missile/target encounter modeling and simulation systems focus on improving probability of kill models. Little research has been done to visualize these encounters. These systems can be made more useful to the engineers by incorporating current computer graphics technology for visualizing and animating the encounter. Our research has been to develop a graphical simulation package for visualizing both endgame and full fly-out encounters. Endgame visualization includes showing the interaction of a missile, its fuze cone proximity sensors, and its target during the final fraction of a second of the missile/target encounter. Additionally, this system displays dynamic effects such as the …

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The Fate And Transport Of Airborne Jp-4 And Jp-8 Aerosol During Cold Startup, Bradford Eugene Buckman Dec 1997

The Fate And Transport Of Airborne Jp-4 And Jp-8 Aerosol During Cold Startup, Bradford Eugene Buckman

Theses and Dissertations

During cold startup (engine warm-up) procedures at northern tier bases, fuel aerosol (JP-4 and JP-8) is emitted before complete combustion of the fuel occurs. The time necessary for complete combustion to occur may be as long as 10 minutes. Hence, during these first few minutes, aerosol is emitted at relatively high concentrations. This research investigates the principle behavior of the emitted aerosol: advection, dispersion, evaporation, and settling. Using previous work in fuel jettisoning and evaporation as a foundation, this thesis investigates the physical factors affecting the airborne concentration of fuel aerosol at different times, the amount of fuel aerosol reaching …

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Breast Cancer Mass Detection Using Difference Of Gaussians And Pulse Coupled Neural Networks, Donald A. Cournoyer Dec 1997

Breast Cancer Mass Detection Using Difference Of Gaussians And Pulse Coupled Neural Networks, Donald A. Cournoyer

Theses and Dissertations

CAD, serving as a second reader, has been shown to improve the success of radiologists at detecting breast cancer. This thesis will develop a new algorithm to identify masses in mammograms. The system developed for this thesis will be capable of assisting a radiologist in making decisions.

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Photoluminescence Study Of Gan Implanted With Erbium And Erbium-Oxygen, Lori R. Everitt Dec 1997

Photoluminescence Study Of Gan Implanted With Erbium And Erbium-Oxygen, Lori R. Everitt

Theses and Dissertations

Erbium emits at 1540 nm, which propagates well through fiber optic cables. This work studies the photoluminescence (PL) from GaN, GaN implanted with Er alone, and GaN implanted with both Er and O as functions of excitation laser energy and sample temperature. When the exciton bound to a neutral donor recombined, a photon was emitted at 3.47 eV. A photon emitted at 3.457 eV may have been evidence of the recombination of an exciton bound to a neutral acceptor. Second, the Er-ion transitions were observed in two groups around 0.805 and 1.25 eV. The PL intensity was measured at four …

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Effects Of Near-Field Scatterers On Space-Time Adaptive Processing, Jonathan W. Fitton Dec 1997

Effects Of Near-Field Scatterers On Space-Time Adaptive Processing, Jonathan W. Fitton

Theses and Dissertations

Near-field scatterers, such as the wing of an airplane, can affect the ability of the processor to null out clutter and jammer signals. The target, clutter, and jammer signals will reflect off the near-field scatterers into the array and appear to be coming from a direction different from their true sources. This thesis develops a theoretical model for the direct path and scattered path signals from the target, clutter, and jamming signals. The optimum weight vector, normally computed using the steering vector to the target and the covariance matrix of the undesired signals, must now include the effects of the …

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Warning Times And Impact Predictions Of Asteroids And Comets On A Collision Course With Earth, Ahren D. Heidt Dec 1997

Warning Times And Impact Predictions Of Asteroids And Comets On A Collision Course With Earth, Ahren D. Heidt

Theses and Dissertations

This study investigates the amount of data and time necessary to accurately predict Earth impacts of Earth Crossing Objects (ECOs). Trajectories are simulated by numerically integrating in an N-Body system. Given final impact parameters, the trajectory is propagated backwards to an earlier time, creating initial conditions and simulated observation data at requested intervals to which Gaussian random noise is introduced. Utilizing a Bayes Filter to estimate position and velocity from the simulated observation data, the estimate is then propagated forward in time to determine whether or not an impact can be accurately predicted. State vectors and covariance matrices are then …

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A Model For Determining Information To Be Captured Regarding Unauthorized Computer Entry Of An Air Force Computer System, Leslie F. Himebrook Dec 1997

A Model For Determining Information To Be Captured Regarding Unauthorized Computer Entry Of An Air Force Computer System, Leslie F. Himebrook

Theses and Dissertations

This thesis presents a model of information to capture regarding unauthorized computer systems access attempts. This model takes a management focus, and incorporates the technical focus, intelligence focus, and legal focus as inputs. The author used an exploratory, qualitative methodology consisting of an extensive literature review and interviews with experts in the field. These efforts produced the proposed model, which was reviewed by experts in the field using a delphi technique. The model consists of information that is divided into the following areas: 1. What information was compromised. 2. What type of intrusion occurred. 3. How the intrusion was attempted. …

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A Representational Approach To Knowledge And Multiple Skill Levels For Broad Classes Of Computer Generated Forces, Larry J. Hutson Dec 1997

A Representational Approach To Knowledge And Multiple Skill Levels For Broad Classes Of Computer Generated Forces, Larry J. Hutson

Theses and Dissertations

Current computer generated forces (CGFs) in the 'synthetic battlespace', a training arena used by the military, exhibit several deficiencies. Human actors within the battlespace rapidly identify these CGFs and defeat them using unrealistic and potentially fatal tactics, reducing the overall effectiveness of this training arena. Simulators attached to the synthetic battlespace host local threat systems, leading to training inconsistencies when different simulators display the same threat at different levels of fidelity. Finally, current CGFs are engineered 'from the ground up', often without exploiting commonalities with other existing CGFs, increasing development (and ultimately training) costs. This thesis addresses these issues by …

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A Single Chip Low Power Implementation Of An Asynchronous Fft Algorithm For Space Applications, Bruce W. Hunt Dec 1997

A Single Chip Low Power Implementation Of An Asynchronous Fft Algorithm For Space Applications, Bruce W. Hunt

Theses and Dissertations

A fully asynchronous fixed point FFT processor is introduced for low power space applications. The architecture is based on an algorithm developed by Suter and Stevens specifically for a low power implementation. The novelty of this architecture lies in its high localization of components and pipelining with no need to share a global memory. High throughput is attained using large numbers of small, local components working in parallel. A derivation of the algorithm from the discrete Fourier transform is presented followed by a discussion of circuit design parameters specifically, those relevant to space applications. The generic architecture is explained with …

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Evaluation Of The Natural Biodegradation Of Aircraft Deicing Fluid Components In Soils, Laura M. Johnson Dec 1997

Evaluation Of The Natural Biodegradation Of Aircraft Deicing Fluid Components In Soils, Laura M. Johnson

Theses and Dissertations

This research effort was conducted to analyze the biodegradation of propylene glycol (PG) and tolyltriazole in two different soil types; a sandy soil and a high clay soil. Both an automated respirometer and a high performance liquid chromatograph (H PLO) were used in the analysis. Two separate experiments were conducted. In the first experiment, one level of tolyltriazole was added to the soils to determine whether or not there was a difference in the biodegradation rates of tolyltriazole in the two soils. The respirometer results indicated that there was a significant difference between the respiration rates of the microorganisms in …

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A Cercla-Based Decision Model To Support Remedy Selection For An Uncertain Volume Of Contaminants At A Doe Facility, Christine E. Kerschus Dec 1997

A Cercla-Based Decision Model To Support Remedy Selection For An Uncertain Volume Of Contaminants At A Doe Facility, Christine E. Kerschus

Theses and Dissertations

The Paducah Gaseous Diffusion Plant (PGDP) operated by the Department of Energy is challenged with selecting the appropriate remediation technology to cleanup contaminants at Waste Area Group (WAG) 6. This research utilizes value focused thinking and multi attribute preference theory concepts to produce a decision analysis model designed to aid the decision makers in their section process. The model is based on CERCLA's five primary balancing criteria, tailored specifically to WAG 6 and the contaminants of concern, utilizes expert opinion and the best available engineering, cost, and performance data, and accounts for uncertainty in contaminant volume. The model ranks 23 …

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From Containment To Cooperation: Collective Action And The Wassenaar Arrangement, Kenneth A. Dursht Dec 1997

From Containment To Cooperation: Collective Action And The Wassenaar Arrangement, Kenneth A. Dursht

Cardozo Law Review

No abstract provided.

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North Carolina Swine Evaluation Station: Adapting To Meet The Needs Of A Rapidly Changing Industry, M Todd See Dec 1997

North Carolina Swine Evaluation Station: Adapting To Meet The Needs Of A Rapidly Changing Industry, M Todd See

Journal of Extension

To meet current and future demands for information needed by specialized and technically advanced pork producers the focus of the North Carolina Swine Evaluation Station was changed. The new program was designed to assist in the definition of production potential and goals, development of least-cost feeding and management strategies, and to provide a rapid response to identified research needs. Data collected on growth performance, carcass merit, and economics have been used to develop mathematical models to help identify and meet production and financial goals while emphasizing the production of a healthy pork product that is desirable to the consumer.

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4-H Classroom Science Programs Enriching The Learning Environment, Robert L. Horton, Joseph Konen Dec 1997

4-H Classroom Science Programs Enriching The Learning Environment, Robert L. Horton, Joseph Konen

Journal of Extension

This study addresses the role of 4-H Classroom Science Programs as a catalyst for enriching the learning environment of students. Convinced that 4-H could have an impact on the quality of science education in the classroom, researchers from The National Center for Science Teaching and Learning and the National 4-H Network for Action in Science and Technology set out to establish a model approach for the delivery of 4-H classroom science programs. The model put forth in this program shows great promise in guiding the science enrichment efforts of 4-H professionals across the country. Clearly, 4-H can play a role …

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Evidence For A Shore-Normal Energy Gradient And Its Character In The Speiekeroog Back Barrier Tidal Flats, German North Sea Coast, N Nyandwi Dec 1997

Evidence For A Shore-Normal Energy Gradient And Its Character In The Speiekeroog Back Barrier Tidal Flats, German North Sea Coast, N Nyandwi

Tanzania Journal of Science

Sediment distribution in the Spiekeroog backbarrier tidal flats has been studied with the aim of identifying the factors controlling their deposition. Form the mainland coast northwards three physiographic units are recognizable namely, the tidal flats adjacent to the coast, the tidal channels with the intervening flats and the dunes and tidal flats adjoining Spiekeroog island. The areal distribution of the sand fraction (˂4.0 phi) shows a shore normal energy gradient with increasing energy towards the sea. Very fine sands are found very close to the mainland coast, fine to very fine in the central part and fine sand on the …

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Air-Snow Exchange Investigations At Summit, Greenland: An Overview, Jack E. Dibb, J L. Jaffrezo Nov 1997

Air-Snow Exchange Investigations At Summit, Greenland: An Overview, Jack E. Dibb, J L. Jaffrezo

Earth Sciences

The Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice Core Project (GRIP) deep drilling programs at Summit, Greenland included support (both logistical and scientific) of extensive investigation of atmospheric transport and air-snow exchange processes of gases and particles relevant to the interpretation of the ice-core records. Much of the sampling for the air-snow exchange investigations was conducted at a unique solar-powered camp 30 km southwest of the GISP2 drill camp (even further from the GRIP camp) and was characterized by a high degree of international collaboration and cooperation. The wide range of expertise and analytical capabilities of the 20-plus …

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Major Features And Forcing Of High‐Latitude Northern Hemisphere Atmospheric Circulation Using A 110,000‐Year‐Long Glaciochemical Series, Paul A. Mayewski, L. David Meeker, Mark S. Twickler, Sallie I. Whitlow, Qinzhao Yang, W. Berry Lyons, Michael Prentice Nov 1997

Major Features And Forcing Of High‐Latitude Northern Hemisphere Atmospheric Circulation Using A 110,000‐Year‐Long Glaciochemical Series, Paul A. Mayewski, L. David Meeker, Mark S. Twickler, Sallie I. Whitlow, Qinzhao Yang, W. Berry Lyons, Michael Prentice

Faculty Publications

The Greenland Ice Sheet Project 2 glaciochemical series (sodium, potassium, ammonium, calcium, magnesium, sulfate, nitrate, and chloride) provides a unique view of the chemistry of the atmosphere and the history of atmospheric circulation over both the high latitudes and mid‐low latitudes of the northern hemisphere. Interpretation of this record reveals a diverse array of environmental signatures that include the documentation of anthropogenically derived pollutants, volcanic and biomass burning events, storminess over marine surfaces, continental aridity and biogenic source strength plus information related to the controls on both high‐ and low‐frequency climate events of the last 110,000 years. Climate forcings investigated …

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A 110,000‐Year History Of Change In Continental Biogenic Emissions And Related Atmospheric Circulation Inferred From The Greenland Ice Sheet Project Ice Core, L. David Meeker, Paul A. Mayewski, Mark S. Twickler, Sallie I. Whitlow, Debra A. Meese Nov 1997

A 110,000‐Year History Of Change In Continental Biogenic Emissions And Related Atmospheric Circulation Inferred From The Greenland Ice Sheet Project Ice Core, L. David Meeker, Paul A. Mayewski, Mark S. Twickler, Sallie I. Whitlow, Debra A. Meese

Faculty Publications

The 110,000‐year record of ammonium concentrations from the Greenland Ice Sheet Project 2 (GISP2) ice core provides the basis for an analysis of terrestrial biological production and atmospheric circulation patterns involved in the transport of biologically produced ammonium to the Greenland atmosphere. The directly measured concentration series was selected for analysis, rather than that of estimated ammonium flux, after a detailed analysis of the relationship among ice core glaciochemical concentrations and a high‐resolution simultaneous record of snow accumulation from the GISP2 core. Analysis of the ammonium concentration series shows that maxima in background levels of ammonium in the Greenland atmosphere …

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