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Using Genetic Algorithms To Map First-Principles Results To Model Hamiltonians: Application To The Generalized Ising Model For Alloys, Gus L. W. Hart, Volker Blum, Michael J. Walorski, Alex Zunger Oct 2005

Using Genetic Algorithms To Map First-Principles Results To Model Hamiltonians: Application To The Generalized Ising Model For Alloys, Gus L. W. Hart, Volker Blum, Michael J. Walorski, Alex Zunger

Faculty Publications

The cluster expansion method provides a standard framework to map first-principles generated energies for a few selected configurations of a binary alloy onto a finite set of pair and many-body interactions between the alloyed elements. These interactions describe the energetics of all possible configurations of the same alloy, which can hence be readily used to identify ground state structures and, through statistical mechanics solutions, find finite-temperature properties. In practice, the biggest challenge is to identify the types of interactions which are most important for a given alloy out of the many possibilities. We describe a genetic algorithm which automates this …

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On-Demand Tutoring In Distance Education: Intrinsically-Motivated, Scalable Interpersonal Interaction To Improve Achievement, Completion, And Satisfaction, Peter B. Williams Oct 2005

On-Demand Tutoring In Distance Education: Intrinsically-Motivated, Scalable Interpersonal Interaction To Improve Achievement, Completion, And Satisfaction, Peter B. Williams

Theses and Dissertations

The purpose of the study was to test an intrinsically-motivated interaction approach, designed to increase distance education support, for both content and motivation, in a cost-effective manner. The literature summarized shows that distance education students desire content and motivational support beyond course materials and are limited in their success without it. Further, while researchers explore increased interaction as a solution, professors usually do not have time for it and attempts to provide it are often restricted by institutions' limited resources. Very little has been published on the effects of distance education tutors and the need for more research in this …

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Direct Enumeration Of Alloy Configurations For Electronic Structural Properties, Gus L. W. Hart, Peter A. Graf, Kwiseon Kim, Wesley B. Jones Oct 2005

Direct Enumeration Of Alloy Configurations For Electronic Structural Properties, Gus L. W. Hart, Peter A. Graf, Kwiseon Kim, Wesley B. Jones

Faculty Publications

We present and apply an approach to directly enumerate the band gaps and effective masses of all possible zinc blende-based alloy configurations whose unit cell contains up to a specified number of atoms. This method allows us to map the space of band gaps and effective masses versus alloy composition and atomic configuration. We demonstrate that a large number of band gaps and effective masses are available. We also discuss convergence of the method with respect to unit cell size and the combined optimization of band gap and effective mass for AlGaAs and GaInP semiconductor alloys.

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Properties Model For Aqueous Sodium Chloride Solutions Near The Critical Point Of Water, Bing Liu Oct 2005

Properties Model For Aqueous Sodium Chloride Solutions Near The Critical Point Of Water, Bing Liu

Theses and Dissertations

Traditional excess Gibbs energy models in terms of temperature, pressure, and concentration become progressively less effective in describing the thermodynamics of aqueous solutions at temperatures above 300 ¢ªC, and are totally inadequate in the critical region of water. This deficiency is due to the strong ion association and the large property fluctuations (such as density) with small variations in pressure, temperature, and solute concentration around the critical point of water. In this work, a speciation-based model has been developed to describe the thermodynamic properties of aqueous sodium chloride solutions in the critical region of water. The anomalous fluctuation problem is …

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Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang Oct 2005

Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang

Theses and Dissertations

A small-scale adiabatic calorimeter has been constructed as part of a larger project to study nano-particles and to facilitate specific heat measurements on samples where it is difficult to obtain enough material to run on the current large-scale adiabatic apparatus. This calorimeter is designed to measure sample sizes of less than 0.8 cc over a temperature range from 13 K to 350 K. Specific heat results on copper, sapphire, and benzoic acid show the accuracy of the measurements to be better than ±0.4% for temperatures higher than 50 K. The reproducibility of these measurements is generally better than ±0.25%. Experimental …

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Historical Land Cover Impacts On Water Quality In The Provo River Watershed, 1975 - 2002, Fredric James Donaldson Oct 2005

Historical Land Cover Impacts On Water Quality In The Provo River Watershed, 1975 - 2002, Fredric James Donaldson

Theses and Dissertations

The Provo River watershed has experienced land cover change over the past several decades. Land cover influences water quality inasmuch as land cover determines the type and quantity of non-point source (NPS) pollutants that may enter the water. This study examines the historical impacts of land cover changes on water quality in the Provo River using remote sensing and statistical analysis. Statistical correlations and linear regressions were used to study the relationship between various land cover types and water quality variables for six years between 1975 and 2002. This thesis supports research finding myriad impacts of urban land cover on …

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Editor's Note, Joseph Drew Oct 2005

Editor's Note, Joseph Drew

Comparative Civilizations Review

No abstract provided.

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The Inspiration For A Different Eden: Chinese Gardening Ideas In England In The Early Modern Period, Yu Liu Oct 2005

The Inspiration For A Different Eden: Chinese Gardening Ideas In England In The Early Modern Period, Yu Liu

Comparative Civilizations Review

No abstract provided.

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Matthew Melko. General War Among Great Powers In World History, Andrew Targowski Oct 2005

Matthew Melko. General War Among Great Powers In World History, Andrew Targowski

Comparative Civilizations Review

No abstract provided.

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Phylogenetic Analysis Of Large Sequence Data Sets, Hyrum Carroll, Mark J. Clement, Keith Crandall, Quinn O. Snell Oct 2005

Phylogenetic Analysis Of Large Sequence Data Sets, Hyrum Carroll, Mark J. Clement, Keith Crandall, Quinn O. Snell

Faculty Publications

Phylogenetic analysis is an integral part of biological research. As the number of sequenced genomes increases, available data sets are growing in number and size. Several algorithms have been proposed to handle these larger data sets. A family of algorithms known as disc covering methods (DCMs), have been selected by the NSF funded CIPRes project to boost the performance of existing phylogenetic algorithms. Recursive Iterative Disc Covering Method 3 (Rec-I-DCM3), recursively decomposes the guide tree into subtrees, executing a phylogenetic search on the subtree and merging the subtrees, for a set number of iterations. This paper presents a detailed analysis …

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Rate-Adaptive Runlength Limited Encoding For High-Speed Infrared Communication, James Cyril Funk Sep 2005

Rate-Adaptive Runlength Limited Encoding For High-Speed Infrared Communication, James Cyril Funk

Theses and Dissertations

My thesis will demonstrate that Rate Adaptive Runlength Limited encoding (RA-RLL) achieves high data rates with acceptable error rate over a wide range of signal distortion/attenuation, and background noise. RA-RLL has performance superior to other infrared modulation schemes in terms of bandwidth efficiency, duty cycle control, and synchronization frequency. Rate adaptive techniques allow for quick convergence of RA-RLL parameters to acceptable values. RA-RLL may be feasibly implemented on systems with non-ideal timing and digital synchronization.

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Polymer Microchips For Capillary Electrophoresis And Electric Field Gradient Focusing Of Biomolecules, Ryan Thomas Kelly Sep 2005

Polymer Microchips For Capillary Electrophoresis And Electric Field Gradient Focusing Of Biomolecules, Ryan Thomas Kelly

Theses and Dissertations

Polymeric materials have seen increasing use as microfluidic device substrates due to their low cost and the simplicity of templated fabrication procedures. I showed that poly(methyl methacrylate) (PMMA) microdevices could be enclosed in a boiling water bath, which allowed the seal to form more quickly than in conventional approaches, and enabled microchannels to remain hydrated throughout the bonding process. Microchip capillary electrophoresis (µ-CE) devices were fabricated using water-based enclosure, and a mixture of fluorescently labeled amino acids was separated in 30 s in these microchips. To create more robust capillary electrophoresis (CE) microdevices with improved separation performance, phase-changing sacrificial materials …

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Importance Resampling For Global Illumination, Justin F. Talbot Sep 2005

Importance Resampling For Global Illumination, Justin F. Talbot

Theses and Dissertations

This thesis develops a generalized form of Monte Carlo integration called Resampled Importance Sampling. It is based on the importance resampling sample generation technique. Resampled Importance Sampling can lead to significant variance reduction over standard Monte Carlo integration for common rendering problems. We show how to select the importance resampling parameters for near optimal variance reduction. We also combine RIS with stratification and with Multiple Importance Sampling for further variance reduction. We demonstrate the robustness of this technique on the direct lighting problem and achieve up to a 33% variance reduction over standard techniques. We also suggest using RIS as …

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On-Disk Sequence Cache (Odsc): Using Excess Disk Capacity To Increase Performance, Christopher Ryan Slade Sep 2005

On-Disk Sequence Cache (Odsc): Using Excess Disk Capacity To Increase Performance, Christopher Ryan Slade

Theses and Dissertations

We present an on-disk sequence cache (ODSC), which improves disk drive performance. An ODSC uses a separate disk partition to store disk data in the order that the operating system requests it. Storing data in this order reduces the amount of seeking that the disk drive must do. As a result, the average disk access time is reduced. Reducing the disk access time improves the performance of the system, especially when booting the operating system, loading applications, and when main memory is limited. Experiments show that our ODSC speeds up application loads by as much as 413%. Our ODSC also …

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Experimental Measurements Of Longitudinal Load Distributions On Friction Stir Weld Pin Tools, Aaron L. Stahl Sep 2005

Experimental Measurements Of Longitudinal Load Distributions On Friction Stir Weld Pin Tools, Aaron L. Stahl

Theses and Dissertations

The longitudinal forces generated from the Friction Stir Welding process are substantial. An understanding of these forces is critical to proper tool design. This study describes a technique to measure the longitudinal force distribution on a friction stir weld pin tool. Total longitudinal forces were recorded on a dynamometer while welding 6061 aluminum with non-threaded pins that varied in length and diameter. A model was developed that characterizes pin force as a function of pin length and diameter. Results suggest that force generally increases with pin length, while forces remain relatively constant with pin diameter. Unexpected force variation was found …

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The Development Of A Small Scale Radio Astronomy Image Synthesis Array For Research In Radio Frequency Interference Mitigation, Jacob L. Campbell Sep 2005

The Development Of A Small Scale Radio Astronomy Image Synthesis Array For Research In Radio Frequency Interference Mitigation, Jacob L. Campbell

Theses and Dissertations

Radio astronomy synthesis imaging arrays are composed of many parabolic reflector antennas. These antennas are designed to be extremely sensitive to detect faint emissions from astronomical sources. Unfortunately, this also makes them susceptible to radio frequency interference (RFI) from man made sources such as orbiting satellites. The radio astronomy research group at Brigham Young University (BYU) is investigating methods to mitigate the effects of RFI in radio astronomy synthesis imaging. Though real-time RFI mitigation has been demonstrated for a large single dish telescope, for synthesis imaging arrays our prior work has consisted solely of algorithm development and computer simulations. To …

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Linear Equality Constraints And Homomorphous Mappings In Pso, Christopher K. Monson, Kevin Seppi Sep 2005

Linear Equality Constraints And Homomorphous Mappings In Pso, Christopher K. Monson, Kevin Seppi

Faculty Publications

We present a homomorphous mapping that converts problems with linear equality constraints into fully unconstrained and lower-dimensional problems for optimization with PSO. This approach, in contrast with feasibility preservation methods, allows any unconstrained optimization algorithm to be applied to a problem with linear equality constraints, making available tools that are known to be effective and simplifying the process of choosing an optimizer for these kinds of constrained problems. The application of some PSO algorithms to a problem that has undergone the mapping presented here is shown to be more effective and more consistent than other approaches to handling linear equality …

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Geologic Map Of The Golden Throne Quadrangle, Wayne And Garfield Counties, Utah, Daniel H. Martin Sep 2005

Geologic Map Of The Golden Throne Quadrangle, Wayne And Garfield Counties, Utah, Daniel H. Martin

Theses and Dissertations

The Golden Throne Quadrangle is located within Capitol Reef National Park, south-central Utah. Geologic mapping of this 1:24,000 scale 7.5 minute quadrangle began in 2003 as the National Parks Service desired to have geologic maps at this scale produced within the park. Stratigraphically, ten bedrock formations and ten Quaternary deposits are exposed within the Golden Throne Quadrangle. Geologic formations range in age from Permian to Jurassic. This map contains details not included on previous geologic maps including; the members of the Carmel, Chinle, and Moenkopi Formations. Additionally, the Page Sandstone is herein mapped as an independent unit. Structurally the Golden …

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Structure Elucidation Of Bioactive Compounds Isolated From Endophytes Of Alstonia Scholaris And Acmena Graveolens, Nicholas James Hundley Sep 2005

Structure Elucidation Of Bioactive Compounds Isolated From Endophytes Of Alstonia Scholaris And Acmena Graveolens, Nicholas James Hundley

Theses and Dissertations

Alstonia scholaris is an evergreen tree native to Southeast Asia and Australia. It is commonly used as a medicinal plant throughout these regions. In the present study, an endophyte of the genus Xylaria was isolated from a stem of Alstonia scholaris, its mycelia and exudate extracted, and the extract assayed for growth inhibition of HeLa cancer cells in vitro. Several known compounds were isolated and identified based on NMR, infrared, and mass spectral data. The compounds identified are 19,20-epoxycytochalasin C; 19,20epoxycytochalasin D; and xylobovide. Two other compounds, fusaric acid and dehydrofusaric acid, were discovered in an endophyte of the Hypocreales …

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An Acyl Radical Cascade Model For The Total Synthesis Of Lyconadin A, Seth W. Grant Sep 2005

An Acyl Radical Cascade Model For The Total Synthesis Of Lyconadin A, Seth W. Grant

Theses and Dissertations

Lyconadin A (1) is a structurally unique Lycopodium alkaloid with antitumor properties, isolated from the club moss Lycopodium complanatum. We are developing a synthetic route to 1 based on a novel 7-exo-trig/6-exo-trig acyl radical cascade cyclization. The synthesis of model acyl radical cascade precursor 23 will be presented. Key features of this synthesis include the suppression of competing elimination during the alkylation of a hindered phenethyl bromide and the use of a lactone as a precursor to a compound bearing two differentially protected primary alcohols. An account of our studies on the model acyl radical cascade cyclization (23 to 24 …

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Identifying Ancestral Haunts, Mary B. Ruvane Sep 2005

Identifying Ancestral Haunts, Mary B. Ruvane

BYU Family Historian

No abstract provided.

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On Valuing Negative Cash Flows Related To Contamination, Asset Removal, Or Functional Obsolescence, Hal B. Heaton Sep 2005

On Valuing Negative Cash Flows Related To Contamination, Asset Removal, Or Functional Obsolescence, Hal B. Heaton

Faculty Publications

Appraisers are frequently faced with having to value future expected negative cash flows. This article will demonstrate that valuing negative cash flows requires a different approach from valuing positive cash flows. The concepts of valuing remediation costs, asset removal costs, and other types of functional obsolescence will be used to illustrate this concept.

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Superdirectivity In Mimo Systems, Michael A. Jensen, Matthew L. Morris, Jon W. Wallace Sep 2005

Superdirectivity In Mimo Systems, Michael A. Jensen, Matthew L. Morris, Jon W. Wallace

Faculty Publications

Multiantenna systems such as devices for multiple-input-multiple-output (MIMO) communication can theoretically use array superdirectivity to optimally exploit the propagation channel. In traditional analyses of MIMO systems, such superdirectivity is not observed due to the commonly applied constraint that limits the excitation current magnitudes. However, when an electromagnetically appropriate constraint on the power radiated by the array is applied, the computed capacity can include effects of transmit superdirectivity. A similar result occurs at the receiver for spatially colored noise. This paper formulates the MIMO system capacity under these circumstances and provides a framework for computing this capacity when the level of …

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Impact Of Receive Amplifier Signal Coupling On Mimo System Performance, Michael A. Jensen, Matthew L. Morris Sep 2005

Impact Of Receive Amplifier Signal Coupling On Mimo System Performance, Michael A. Jensen, Matthew L. Morris

Faculty Publications

This paper uses a detailed model of multiple input multiple output (MIMO) systems to explore the impact of signal coupling in the receiver front end on communication capacity. The model is applied to assess the performance of a MIMO system with two transmit and receive antennas in a simulated multipath environment for different amplifier coupling levels. The results show that in practical scenarios where simple impedance matching techniques are used, the circuit coupling can reduce the signal-to-noise ratio at the receiver and therefore degrade the achievable MIMO capacity.

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Effect Of Melatonin And Dopamine In Site Specific Phosphorylation Of Phosducin In Intact Retina, Arinzechukwu Okere Nkemdirim Aug 2005

Effect Of Melatonin And Dopamine In Site Specific Phosphorylation Of Phosducin In Intact Retina, Arinzechukwu Okere Nkemdirim

Theses and Dissertations

Phosducin (Pdc) is a 28 kDa binding partner for the G protein beta gamma subunit dimer (G-beta-gamma) found abundantly in the photoreceptor cells of the retina and pineal gland. In the retina, light-dependent changes in cAMP and Ca2+ control the phosphorylation of Pdc at serine 73 and 54, respectively, which in turn controls the binding of Pdc to G protein beta gamma subunit dimer . G protein beta gamma subunit dimer binding has been proposed to facilitate light-driven transport of G protein beta gamma subunit dimer from the site of phototransduction in the outer segment of the photoreceptor cell to …

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Studies In The Dynamics Of Economic Systems, Christophe G. Giraud-Carrier, Kevin Seppi, Nghia Tran, Sean C. Warnick, W. Samuel Weyerman, R. Johnson Aug 2005

Studies In The Dynamics Of Economic Systems, Christophe G. Giraud-Carrier, Kevin Seppi, Nghia Tran, Sean C. Warnick, W. Samuel Weyerman, R. Johnson

Faculty Publications

This paper demonstrates the utility of systems and control theory in the analysis of economic systems. Two applications demonstrate how the analysis of simple dynamic models sheds light on important practical problems. The first problem considers the design of a retail laboratory, where the small gain theorem enables the falsification of pricing policies. The second problem explores industrial organization using the equilibria of profit-maximizing dynamics to quantify the percentage of a firm’s profits due strictly to the cooperative effects among its products. This ”Value of Cooperation” suggests an important measure for both organizational and antitrust applications.

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Challenging Policies That Do Not Play Fair: A Credential Relevancy Framework Using Trust Negotiation Ontologies, Travis S. Leithead Aug 2005

Challenging Policies That Do Not Play Fair: A Credential Relevancy Framework Using Trust Negotiation Ontologies, Travis S. Leithead

Theses and Dissertations

This thesis challenges the assumption that policies will "play fair" within trust negotiation. Policies that do not "play fair" contain requirements for authentication that are misleading, irrelevant, and/or incorrect, based on the current transaction context. To detect these unfair policies, trust negotiation ontologies provide the context to determine the relevancy of a given credential set for a particular negotiation. We propose a credential relevancy framework for use in trust negotiation that utilizes ontologies to process the set of all available credentials C and produce a subset of credentials C' relevant to the context of a given negotiation. This credential relevancy …

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Generation Of Biomarkers From Anthrax Spores By Catalysis And Analytical Pyrolysis, Phillip R. Smith Aug 2005

Generation Of Biomarkers From Anthrax Spores By Catalysis And Analytical Pyrolysis, Phillip R. Smith

Theses and Dissertations

Anthrax spores, in weaponized form, are dangerous biological warfare agents. Handheld technology for the rapid detection of anthrax is greatly needed to improve national security. Methods to detect anthrax spores are diverse, with most taking at least an hour for positive identification. A viable option for rapid detection is analytical pyrolysis (AP), which produces chemicals containing taxonomical information (biomarkers). AP methods are reviewed and critically analyzed to show that reproducible detection of anthrax spores in a rapid manner (< 5 min) with a handheld device is not currently possible. A promising alternative to AP is the use of a catalyst to produce biomarkers from anthrax spores with improved selectivity and reproducibility. Catalytic materials having promise for this include platinum, nickel, and superacids. Experiments evaluating several of these materials are described. A biomarker mass spectral library was created, based on information available in the scientific literature, to facilitate analysis and identification of the biomarkers produced experimentally. The RAMFAC algorithm was used to deconvolute chromatographic peaks to produce clean mass spectra and match them against entries in the biomarker library. While the library is not complete, its use with the RAMFAC algorithm enabled detection of many important biomarkers in experiments involving catalytic breakdown of anthrax spores. Experimental results from preliminary tests of several catalysts are presented and discussed. Addition of catalysts in the form of platinum nanoclusters and superacids to bacterial spores in a commercial pyrolyzer effected an increase in the amount of biomarkers produced at mild conditions over traditional pyrolysis methods. Electroformed nickel mesh, on the other hand, demonstrated low catalytic activity for the production of biomarkers, likely due to poor contact of the spores with the mesh. Biomarkers similar to those published in the literature were observed, including dipicolinic acid, picolinic acid, propionamide, acetamide, diketopiperazines, fatty acids, furfuryl alcohol, and DNA bases. A statistically designed factorial study was used to determine the importance of temperature, spore loading, and nanocluster loading on the production of three important biomarkers. The relative importance of these variables differs for each of the three important biomarkers, suggesting they are produced by different reaction mechanisms.

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Dynamic Dead Variable Analysis, Micah S. Lewis Aug 2005

Dynamic Dead Variable Analysis, Micah S. Lewis

Theses and Dissertations

Dynamic dead variable analysis (DDVA) extends traditional static dead variable analysis (SDVA) in the context of model checking through the use of run-time information. The analysis is run multiple times during the course of model checking to create a more precise set of dead variables. The DDVA is evaluated based on the amount of memory used to complete model checking relative to SDVA while considering the extra overhead required to implement DDVA. On several models with a complex control flow graph, DDVA reduces the amount of memory needed by 38-88MB compared to SDVA with a cost of 36 bytes of …

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Using Box-Scores To Determine A Position's Contribution To Winning Basketball Games, Garritt L. Page Aug 2005

Using Box-Scores To Determine A Position's Contribution To Winning Basketball Games, Garritt L. Page

Theses and Dissertations

Basketball is a sport that has become increasingly popular world-wide. At the professional level it is a game in which each of the five positions has a specific responsibility that requires unique skills. It seems likely that it would be valuable for coaches to know which skills for each position are most conducive to winning. Knowing which skills to develop for each position could help coaches optimize each player's ability by customizing practice to contain drills that develop the most important skills for each position that would in turn improve the team's overall ability. Through the use of Bayesian hierarchical …

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