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Retrospective Theses and Dissertations

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Full-Text Articles in Physical Sciences and Mathematics

Asymptotic Behavior Of The Solutions To A Family Of Pde's Arising From The Chemotaxis Equations Of Keller And Segal, Matthew Alan Halverson Jan 2008

Asymptotic Behavior Of The Solutions To A Family Of Pde's Arising From The Chemotaxis Equations Of Keller And Segal, Matthew Alan Halverson

Retrospective Theses and Dissertations

The system ut = uxx - (uvx)x, vt = u - Av is considered where A is a non-negative, self-adjoint operator which commutes with the Laplacian. The operator is considered to have eigenvalues lambda n = nrholambda1, and the system is considered on [0,1] x [0,T] with homogeneous Neumann boundary conditions. The operators which lead to global solutions and those that lead to solutions which blow up in finite time are considered as a function of rho, using an application of the methods of Hillen and Potapov [Math. Methods Appl. Sci., 27 (2004), pp. 1783-1801] to analyze the global case and those ...


Inductively Coupled Plasma: Fundamental Particle Investigations With Laser Ablation And Applications In Magnetic Sector Mass Spectrometry, Nathan Joe Saetveit Jan 2008

Inductively Coupled Plasma: Fundamental Particle Investigations With Laser Ablation And Applications In Magnetic Sector Mass Spectrometry, Nathan Joe Saetveit

Retrospective Theses and Dissertations

Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of ...


Lie Algebra Decompositions With Applications To Quantum Dynamics, Mehmet DaǧLı Jan 2008

Lie Algebra Decompositions With Applications To Quantum Dynamics, Mehmet DaǧLı

Retrospective Theses and Dissertations

Lie group decompositions are useful tools in the analysis and control of quantum systems. Several decompositions proposed in the literature are based on a recursive procedure that systematically uses the Cartan decomposition theorem. In this dissertation, we establish a link between Lie algebra gradings and recursive Lie algebra decompositions, and then we formulate a general scheme to generate Lie group decompositions. This scheme contains some procedures previously proposed as special cases and gives a virtually unbounded number of alternatives to factor elements of a Lie group.


Intercept System To Edit, Control, And Analyze Packets (Isecap), Grant Rogers Brinkmeyer Jan 2008

Intercept System To Edit, Control, And Analyze Packets (Isecap), Grant Rogers Brinkmeyer

Retrospective Theses and Dissertations

ISECAP is an advanced packet filtering framework designed for use with the Internet Scale Event and Attack Generation Environment (ISEAGE) at Iowa State University. ISEAGE is a network security test bed where cyber attacks can be carried out for security research. ISECAP functions as a FreeBSD-based general purpose packet control system designed to alter ISEAGE network data as it is being transmitted. Scripts are interpreted by ISECAP to modify network data in real-time, assisting in the simulation and obfuscation of various network attacks tested at the ISEAGE facility. The ISECAP system is developed as a flexible tool with a forward ...


Developments In Icp-Ms: Electrochemically Modulated Liquid Chromatography For The Clean-Up Of Icp-Ms Blanks And Reduction Of Matrix Effects By Flow Injection Icp-Ms, Cory Thomas Gross Jan 2008

Developments In Icp-Ms: Electrochemically Modulated Liquid Chromatography For The Clean-Up Of Icp-Ms Blanks And Reduction Of Matrix Effects By Flow Injection Icp-Ms, Cory Thomas Gross

Retrospective Theses and Dissertations

The focus of this dissertation is the development of techniques with which to enhance the existing abilities of inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS is a powerful technique for trace metal analysis in samples of many types, but like any technique has certain strengths and weakness. Attempts are made to improve upon those strengths and to overcome certain weaknesses.;One standout figure of merit for ICP-MS is limit of detection. With today's advances in instrumental hardware the limit of detection is often limited by the purity of the blank. While the limit of detection itself is not evaluated ...


Development And Application Of A Hybrid Femtosecond/Picosecond Coherent Raman Probe Designed For Study Of Excited State Systems, Benjamin Douglas Prince Jan 2008

Development And Application Of A Hybrid Femtosecond/Picosecond Coherent Raman Probe Designed For Study Of Excited State Systems, Benjamin Douglas Prince

Retrospective Theses and Dissertations

The conversion from purely femtosecond coherent anti-Stokes Raman spectroscopy (CARS) to a more advantageous hybrid femtosecond/picosecond CARS (fs/ps CARS) probe for time-resolved vibrational dynamics studies is detailed. This probe provides a number of benefits for the use of studying the evolution of electronically excited states, including rapid data acquisition speeds, increased spectral resolution, and discrimination against competing background signals. The high time resolution is shown to depend on the cross correlation of the excitation pulse and initial CARS pulses while the high frequency resolution is shown to depend on the final CARS electric field. The pump-fs/ps CARS ...


Practical Tools For Exploring Data And Models, Hadley Alexander Wickham Jan 2008

Practical Tools For Exploring Data And Models, Hadley Alexander Wickham

Retrospective Theses and Dissertations

No abstract provided.


An Assessment Of Riparian Land-Use And Channel Condition Impacts On Streambank Eroding Lengths And Recession Rates In Two Third Order Rural Watersheds In Central Iowa, Jason Alan Palmer Jan 2008

An Assessment Of Riparian Land-Use And Channel Condition Impacts On Streambank Eroding Lengths And Recession Rates In Two Third Order Rural Watersheds In Central Iowa, Jason Alan Palmer

Retrospective Theses and Dissertations

Over the 150 year history of major agricultural activity in Iowa nearly all the native prairie (99.9%) and wetlands (95%) were lost as native plant communities were converted to row-crop agriculture. This major change from perennial to annual upland vegetation was accompanied by broad scale installation of tile drainage intended to remove moisture from saturated wetland soils, increasing available crop land. The increased removal of water by tile drainage accompanied by the increase in surface runoff caused by the loss of permanent soil cover and compaction resulted in an increase in the rate and amount of water entering stream ...


A Specification Language Design For The Java Modeling Language (Jml) Using Java 5 Annotations, Kristina Boysen Taylor Jan 2008

A Specification Language Design For The Java Modeling Language (Jml) Using Java 5 Annotations, Kristina Boysen Taylor

Retrospective Theses and Dissertations

Design by contract specification languages help programmers write their intentions for a piece of code in a formal mathematical language. Most programming languages do not have built-in syntax for such specifications, so many design by contract languages place specifications in comments. The Java Modeling Language (JML) is one such specification language for Java that uses comments to specify contracts. However, starting with version 5, Java has introduced annotations, a syntactical structure to place metadata in various places in the code. This thesis proposes an initial design to writing JML contracts in the Java 5 annotation syntax and evaluates several criteria ...


Uncovering The Structure Of Hypergraphs Through Tensor Decomposition: An Application To Folksonomy Analysis, Flavian Vasile Jan 2008

Uncovering The Structure Of Hypergraphs Through Tensor Decomposition: An Application To Folksonomy Analysis, Flavian Vasile

Retrospective Theses and Dissertations

Folksonomies - shared vocabularies generated by users through collective annotation (tagging) of web-based content, which are formally hypergraphs connecting users, tags and objects, are beginning to play an increasingly important role in social media. Effective use of folksonomies for organizing and locating web content, discovering and organizing user communities in order to facilitate the contact and collaboration between users who share parts of their interests and attitudes calls for effective methods for discovering coherent groupings of users, objects, and tags. We empirically compare the results of several folksonomy clustering methods using tensor decompositions such as PARAFAC, Tucker3 and HOSVD which are ...


A Static Analysis Of Maximum Wind Penetration In Iowa And A Dynamic Assessment Of Frequency Response In Wind Turbine Types, Eknath Vittal Jan 2008

A Static Analysis Of Maximum Wind Penetration In Iowa And A Dynamic Assessment Of Frequency Response In Wind Turbine Types, Eknath Vittal

Retrospective Theses and Dissertations

As the energy industry moves into the 21st century the use and research into renewable resources has expanded significantly. Whether it is wind, biomass, or solar, the industry is seeking ways to breakthrough and integrate the newest technologies into their power systems. Wind energy, in particular, has seen significant expansion since the 1980's, with generating capability of wind turbines increasing dramatically from 50 kW to nearly 5 MW presently. Seeking to introduce larger levels of wind generation in the Iowa electricity system, the goal of this thesis was to: First, determine the maximum wind penetration level of the existing ...


Photometric Variability Of Sun-Like Stars In The Old Open Cluster M67, Ryan Wesley Tobin Jan 2008

Photometric Variability Of Sun-Like Stars In The Old Open Cluster M67, Ryan Wesley Tobin

Retrospective Theses and Dissertations

Few physical processes can affect the earth's climate on a global scale. The variability of the Sun is one such process. The Sun is known to vary by about 0.1% due to Sunspots and other surface activity. We do not yet know whether the Sun's variability is normal. Using the well-known properties of the old open cluster M67, we look for variations in Sun-like stars.;In this thesis, we present the results of observation, calibration, correction and analysis of stars in M67. We focus on Sun-like stars and binary systems. We also determine the limits of observation ...


Decision Making Limitations From Communication Barriers In Government Structures In Chinese Rural Energy Projects, Nathan Gregory Johnson Jan 2008

Decision Making Limitations From Communication Barriers In Government Structures In Chinese Rural Energy Projects, Nathan Gregory Johnson

Retrospective Theses and Dissertations

Field research was conducted in the Li Cheng District (about 1,200 km 2) of Shan Dong Province. Data collection occurred during a two-week period in July 2006. At that time, seven villages represented all relevant sites in the district that contained gasification technologies. Small-group interviews with village leaders, station managers, and community members were conducted locally. Contact with external government agencies and technology scientists completed the set of potential stakeholders.;This study analyzes the failure of state-owned energy development initiatives in China. Communication barriers in bureaucratic structures and culturally prescribed patterns of interaction were revealed as inhibiting information transfer ...


The Geochemistry Of Carbonate-Hosted Pb-Zn-Ag Mineralization In The Lavrion District, Attica, Greece: Fluid Inclusion, Stable Isotope, And Rare Earth Element Studies, Todd Andrew Bonsall Jan 2008

The Geochemistry Of Carbonate-Hosted Pb-Zn-Ag Mineralization In The Lavrion District, Attica, Greece: Fluid Inclusion, Stable Isotope, And Rare Earth Element Studies, Todd Andrew Bonsall

Retrospective Theses and Dissertations

Carbonate-replacement Pb-Zn-Ag deposits in the Lavrion district, Greece, are spatially related to a 7 to 10 Ma granodiorite intrusion and various sills and dikes of mafic to acid composition. The Plaka granodiorite contains porphyry molybdenite mineralization and is spatially associated with a Cu-Fe skarn. Carbonate-replacement deposits occur predominantly in marbles (Upper and Lower marble of the Basal Unit), Kaesariani schists, and along a major detachment fault. Orebodies are mainly manto-style, but mineralization also occurs in veins. The mineralogy of carbonate-replacement deposits is dominated by base metal sulfides and sulfosalts of Ag, Bi, Sn, Sb, As, and Pb, particularly at Plaka ...


Impacts Of Mass Media Coverage Of The Economy During Normal Times And Recessions On The Index Of Consumer Confidence Using Time Series Analysis And Granger Causal Analysis, Lishan Su Jan 2008

Impacts Of Mass Media Coverage Of The Economy During Normal Times And Recessions On The Index Of Consumer Confidence Using Time Series Analysis And Granger Causal Analysis, Lishan Su

Retrospective Theses and Dissertations

The level of consumer sentiment influences decision making of policy makers, and therefore it is important to examine if media have powerful impacts on consumer sentiment. Based on the theories of business cycles and second-level agenda-setting, this study applies Granger causal analysis and time series analysis to explore the causal relationships among economic reporting by media, consumer sentiment and the real state of the economy embodied in Business Week, the Index of Consumer Confidence (CCI) and the Standard & Poor's 500 (S&P 500). The results indicate that interpretation by media have only limited effects on the level of consumer ...


Managing Continuous K-Nearest Neighbor Queries In Mobile Peer-To-Peer Networks, Patricio A. Galdames S Jan 2008

Managing Continuous K-Nearest Neighbor Queries In Mobile Peer-To-Peer Networks, Patricio A. Galdames S

Retrospective Theses and Dissertations

A continuous k nearest neighbor (CKNN) query retrieves the set of k mobile nodes that are nearest to a query point, and provides real-time updates whenever this set of nodes changes. A CKNN query can be either stationary or mobile, depending on the mobility of its query point. Efficient processing of CKNN queries is essential to many applications, yet most existing techniques assume a centralized system, where one or more central servers are used for query management. In this thesis, we assume a fully distributed mobile peer-to-peer system, where mobile nodes are the only computing devices, and present a unified ...


Computational And Wind Tunnel Studies Of Shelterbelts For Reduction Of Wind Flow And Wind-Induced Loads On Low-Rise Buildings, Sarah Ruth Schmidt Jan 2008

Computational And Wind Tunnel Studies Of Shelterbelts For Reduction Of Wind Flow And Wind-Induced Loads On Low-Rise Buildings, Sarah Ruth Schmidt

Retrospective Theses and Dissertations

Numerical and experimental tests were done to determine the optimum design parameters of a shelterbelt for wind damage mitigation to structures behind the shelterbelt. The Wang and Takle shelterbelt numerical model was used to study the shelterbelt's cross-sectional shape, height, spacing/line tightness, density/density distribution, line width, number of lines, and wind speed parameters. The numerical model was also used to study the effectiveness of more realistically shaped shelterbelt tree lines, rather than using the traditional blocks to represent each line of trees in the shelterbelt. Finally, experiments were conducted in a wind tunnel to test the effects ...


A Formal Approach Toward Authenticated Authorization Without Identification, Lucas D. Witt Jan 2008

A Formal Approach Toward Authenticated Authorization Without Identification, Lucas D. Witt

Retrospective Theses and Dissertations

Anonymity is a valued commodity on the Internet many uses take advantage of. Unfortunately, anonymity and credibility are essentially mutually exclusive. A practical method to determine request creditability without also inheriting the capability to identify the exclusive source of a request is not in practice. Previous research efforts have proposed methods to ensure anonymous communication, but most sacrifice either authorization or privacy. We propose a scheme that allows a message sender to prove his or her creditability without also providing any participant capability to identify the source. In addition, the scheme is resists sybil attacks and disjoints correlation of independent ...


Global Behavior Of Graph Dynamics With Applications To Markov Chains, Jose Ayala-Hoffmann Jan 2008

Global Behavior Of Graph Dynamics With Applications To Markov Chains, Jose Ayala-Hoffmann

Retrospective Theses and Dissertations

No abstract provided.


Terrestrial Arthropod Community And Indicators Of Biotic Integrity For Iowa Tallgrass Prairie, Jessica Marie Orlofske Jan 2008

Terrestrial Arthropod Community And Indicators Of Biotic Integrity For Iowa Tallgrass Prairie, Jessica Marie Orlofske

Retrospective Theses and Dissertations

The tallgrass prairie has become one of the most endangered ecosystems in North America. Thus, there have been attempts to restore and reconstruct native tallgrass prairie. Arthropods, the most diverse taxonomic group on the prairie, have not received adequate attention. A comprehensive arthropod survey in Iowa prairies has not been attempted since the 1930's, and therefore lacks information regarding recent prairie restoration efforts. Arthropods can also provide valuable information related to ecosystem function or biotic integrity when used as bioindicators. However, effective, reliable arthropod bioindicators have not been clearly identified. A survey of arthropods using sweep net transects was ...


Ecology Of Elk Parturition Across Winter Feeding Opportunities In The Brucellosis Endemic Area Of Wyoming, Andrea Ellen Barbknecht Jan 2008

Ecology Of Elk Parturition Across Winter Feeding Opportunities In The Brucellosis Endemic Area Of Wyoming, Andrea Ellen Barbknecht

Retrospective Theses and Dissertations

This study was initiated to examine parturition related behavior both from an ecological perspective and to investigate implications for brucellosis transmission risk among elk and between elk and cattle. These aspects were investigated for elk fed during the winter, elk using improved winter feedlines, and free-ranging elk. Brucellosis is a disease causing abortion in elk ( Cervus elaphus nelsoni), bison (Bos bison), and cattle (Bos spp.). The most common transmission route is through oral contact with aborted fetuses or parturition tissues/fluids and transmission risk is dependent on contact rates. Vaginal implant transmitters were deployed on winter free-ranging elk and elk ...


A Comparative Study Of Roth-Erev And Modied Roth-Erev Reinforcement Learning Algorithms For Uniform-Price Double Auctions, Mridul Pentapalli Jan 2008

A Comparative Study Of Roth-Erev And Modied Roth-Erev Reinforcement Learning Algorithms For Uniform-Price Double Auctions, Mridul Pentapalli

Retrospective Theses and Dissertations

This work focuses on multi-agent learning in market contexts. It reports findings from a comparative study of three reinforcement learning algorithms currently in use for a variety of market applications. Two double-auction market testbeds are developed and used to carry out benchmark comparisons involving intensive parameter sweeps with heat map visualization of parameter sensitivities. A primary concern is the degree to which each tested algorithm permits learning agents to converge to the choice of a best action measured in terms of accumulated profits. Some findings from a mathematical analysis of the algorithms' properties are also reported.;The three reinforcement learning ...


Cryptic Backup: A Framework For Automated Compression, Encryption, And Backup Of Data, Christopher David Hoff Jan 2008

Cryptic Backup: A Framework For Automated Compression, Encryption, And Backup Of Data, Christopher David Hoff

Retrospective Theses and Dissertations

Historically, creating backups of valuable computer data has been arduous, tedious, and time consuming for the average computer user. The increasing concern of encrypting sensitive information has added another layer of complexity to the process. The challenge is creating a single product that encrypts and backs up data on an automated schedule. Likewise, it must decrypt and restore the data with ease. To specifically address this problem, the Cryptic Backup daemon was developed. The daemon schedules and automatically runs backup plans based on user preferences. To demonstrate the power of the daemon, the Cryptic Backup client application was developed. The ...


The Impact Of Upper-Level Flow Regime Change From Spring To Summer On Qpf Accuracy Over The Midwest, Mark R. Loeffelbein Jan 2008

The Impact Of Upper-Level Flow Regime Change From Spring To Summer On Qpf Accuracy Over The Midwest, Mark R. Loeffelbein

Retrospective Theses and Dissertations

Quantitative precipitation forecasts (QPF) are potentially the most significant challenge of weather forecasting, and have been historically difficult for numerical weather prediction (NWP) models to produce. Given the importance of QPF to weather forecasts, there is a need to improve its accuracy. Understanding and recognizing patterns prone to produce errors in model QPF can help predictions made by weather forecasters.;The low level jet (LLJ) observed over the Great Plains is responsible for supporting warm-season convection by transporting heat and moisture into the Midwest. This study examines the two types of dominant mid and upper-level flow patterns during the warm-season ...


Visualization For Network Forensic Analyses: Extending The Forensic Log Investigator (Fli), Paul Michael Miller Jan 2008

Visualization For Network Forensic Analyses: Extending The Forensic Log Investigator (Fli), Paul Michael Miller

Retrospective Theses and Dissertations

In a network attack investigation, the mountain of information collected from varying sources can be daunting. Investigators face significant challenges in being able to correlate findings from these sources, given difficulties with time synchronization. In addition, it is difficult to obtain summary or overview information for one set of data, much less the entire case. This, in turn, makes it nearly impossible to accurately identify missing information.;Identifying these information gaps is one problem, yet another is filling them in. Investigators must rely on legal processes and requests to obtain the information they need. However, it is extremely important they ...


Reference Models For Network Trace Anonymization, Shantanu Gattani Jan 2008

Reference Models For Network Trace Anonymization, Shantanu Gattani

Retrospective Theses and Dissertations

Network security research can benefit greatly from testing environments that are capable of generating realistic, repeatable and configurable background traffic. In order to conduct network security experiments on systems such as Intrusion Detection Systems and Intrusion Prevention Systems, researchers require isolated testbeds capable of recreating actual network environments, complete with infrastructure and traffic details. Unfortunately, due to privacy and flexibility concerns, actual network traffic is rarely shared by organizations as sensitive information, such as IP addresses, device identity and behavioral information can be inferred from the traffic. Trace data anonymization is one solution to this problem. The research community has ...


Vibrational Dynamics Of Excited States Probed By Fs/Ps Cars: Simulations And Applications To Ultrafast Charge Transfer Dynamics, Beth Marie Prince Jan 2008

Vibrational Dynamics Of Excited States Probed By Fs/Ps Cars: Simulations And Applications To Ultrafast Charge Transfer Dynamics, Beth Marie Prince

Retrospective Theses and Dissertations

The subpicosecond time evolution of a push-pull stilbene, 4-dimethylamino-4'-nitrostilbene (DANS) following 400 nm excitation in acetonitrile is observed with vibrational resolution using the recently-developed fs/ps CARS probe technique. Raman-active modes in the fingerprint region of the vibrational spectrum are observed to evolve, both in intensity and in frequency. The evolution of the DANS vibrational spectrum in the nitro symmetric stretch region is probed, exhibiting a frequency upshift on a 300 fs timescale. These findings agree well with timescales observed in transient absorption/gain experiments and support the formation of an intramolecular charge transfer (ICT) state on a subpicosecond ...


A Simulation Assessment Of The Boone River Watershed: Baseline Calibration/Validation Results And Issues, And Future Research Needs, Philip Walter Gassman Jan 2008

A Simulation Assessment Of The Boone River Watershed: Baseline Calibration/Validation Results And Issues, And Future Research Needs, Philip Walter Gassman

Retrospective Theses and Dissertations

A SWAT modeling framework has been constructed for the Boone River Watershed (BRW) in north central Iowa, to support further testing of SWAT and analyses of alternative management practice and/or cropping system scenarios. The BRW covers over 237,000 ha and is an intensively cropped region dominated by corn and soybean production. Nitrate losses are of particular concern in the BRW, especially through subsurface tiles that drain the predominantly flat landscapes that persist throughout the watershed. The modeling system features an intensive set of management, land use, and soil data developed at the Common Land Unit (CLU) level. The ...


Influences Of Midtropospheric Perturbations On Summer Convective Storms Over The United States Northern Plains, Shih-Yu Wang Jan 2008

Influences Of Midtropospheric Perturbations On Summer Convective Storms Over The United States Northern Plains, Shih-Yu Wang

Retrospective Theses and Dissertations

No abstract provided.


Understanding Protein Motions By Computational Modeling And Statistical Approaches, Lei Yang Jan 2008

Understanding Protein Motions By Computational Modeling And Statistical Approaches, Lei Yang

Retrospective Theses and Dissertations

Because of its appealing simplicity, the elastic network model (ENM) has been widely accepted and applied to study many molecular motion problems, such as the molecular mechanisms of chaperonin GroEL-GroES function, allosteric changes in hemoglobin, ribosome motions, motor-protein motions, and conformational changes in general. In this dissertation, the ENM is employed to study various protein dynamics problems, and its validity is also examined by comparing with experimental data. First, we apply principal component analysis (PCA) to identify the essential protein motions from multiple structures (X-ray, NMR and MD) of the HIV-1 protease. We find significant similarities between the first few ...