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2003

Brigham Young University

Articles 1 - 30 of 48

Full-Text Articles in Physical Sciences and Mathematics

Self-Aligned Mechanical Attachment Of Carbon Nanotubes To Silicon Dioxide Structures By Selective Silicon Dioxide Chemical-Vapor Deposition, Jed D. Whittaker, Ghaleb A. Husseini, Matthew A. Linford, Robert C. Davis, Markus Brink Dec 2003

Self-Aligned Mechanical Attachment Of Carbon Nanotubes To Silicon Dioxide Structures By Selective Silicon Dioxide Chemical-Vapor Deposition, Jed D. Whittaker, Ghaleb A. Husseini, Matthew A. Linford, Robert C. Davis, Markus Brink

Faculty Publications

A self-aligned thin-film deposition technique was developed to mechanically attach carbon nanotubes to surfaces for the fabrication of structurally robust nanotube-based nanomechanical devices. Single-walled carbon nanotubes were grown by thermal chemical-vapor deposition (CVD) across 150-nm-wide SiO2 trenches. The nanotubes were mechanically attached to the trench tops by selective silicon tetraacetate-based SiO2 CVD. No film was deposited on the nanotubes where they were suspended across the trenches.

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A Study Of The Suitability Of Irobex For High-Speed Exchange Of Large Data Objects, Casey T. Deccio, Joseph Ekstrom, Charles D. Knutson, D. Ryan Partridge, Kevin B. Tew Dec 2003

A Study Of The Suitability Of Irobex For High-Speed Exchange Of Large Data Objects, Casey T. Deccio, Joseph Ekstrom, Charles D. Knutson, D. Ryan Partridge, Kevin B. Tew

Faculty Publications

This paper demonstrates that careful tuning of the OBEX and IrLAP negotiated parameters allows OBEX to scale well for use with large data objects and high transmission rates. Due to the substantial time overhead inherent in link turnarounds, minimizing turnarounds during the transmission of a large object helps to maximimize link efficiency. The IrLAP window size and OBEX packet size significantly impact the number of required turnarounds during the transmission of a large object. When these parameters are properly tuned, maximum throughput can be achieved, and OBEX performs efficiently at high data rates.

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Delineation Of Mass Movement Prone Areas By Landsat 7 And Digitial Image Processing, Shiloh Marie Howland Dec 2003

Delineation Of Mass Movement Prone Areas By Landsat 7 And Digitial Image Processing, Shiloh Marie Howland

Theses and Dissertations

The problem of whether Landsat 7 data could be used to delineate areas prone to mass movement, particularly debris flows and landslides, was examined using three techniques: change detection in NDVI (Normalized Difference Vegetation Index), change detection in band 5, and the tasseled cap transformation. These techniques were applied to areas that had recently experienced mass movement: Layton, Davis County and Alpine, Spanish Fork Canyon and Santaquin, Utah County. No distinctive spectral characteristics were found with any of these techniques with two possible explanations: 1. That despite improved spatial resolution in Landat 7 over its predecessors and improved digital image …

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Long Coherence Times At 300 K For Nitrogen-Vacancy Center Spins In Diamond Grown By Chemical Vapor Deposition, John S. Colton, T. A. Kennedy, J. E. Butler, R. C. Linares, P.J. Doering Nov 2003

Long Coherence Times At 300 K For Nitrogen-Vacancy Center Spins In Diamond Grown By Chemical Vapor Deposition, John S. Colton, T. A. Kennedy, J. E. Butler, R. C. Linares, P.J. Doering

Faculty Publications

Electron-spin-echo experiments reveal phase-memory times as long as 58 μs at 300 K for nitrogen-vacancy centers in chemical vapor deposition (CVD) single crystals. The spins were optically polarized and optically detected. Two high-quality CVD samples were studied. From the current results, it is not clear whether these phase-memory times represent a fundamental limit or are limited by an external source of decoherence.

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Ordering Tendencies In Octahedral Mgo-Zno Alloys, Gus L. W. Hart, Mahdi Sanati, Alex Zunger Oct 2003

Ordering Tendencies In Octahedral Mgo-Zno Alloys, Gus L. W. Hart, Mahdi Sanati, Alex Zunger

Faculty Publications

Isostrutural II-VI alloys whose components are either rocksalt stable (e.g., CaO-MgO) or zincblende stable (e.g., ZnS-ZnSe) are known to be thermodynamically unstable at low temperatures, showing a miscibility gap and no bulk ordering. In contrast, we show that heterostructural MgO-ZnO is stable, under certain conditions, in the sixfold-coordinated structure for Zn concentrations below 67%, giving rise to spontaneously ordered alloys. Using first-principles calculations, we explain the origin of this stability, the structures of their low-temperature ordered phases, short-range-order patterns, and their optical band-gap properties.

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Allowed Mesoscopic Point Group Symmetries In Domain Average Engineering Of Perovskite Ferroelectric Crystals, Dorian M. Hatch, H. T. Stokes, W. Cao Oct 2003

Allowed Mesoscopic Point Group Symmetries In Domain Average Engineering Of Perovskite Ferroelectric Crystals, Dorian M. Hatch, H. T. Stokes, W. Cao

Faculty Publications

In multivariant systems, several energetically degenerate low temperature domain states can be produced at the structural phase transition. Coexistence of these domain states can produce mesoscopic structures that possess symmetries distinct from the microscopic single domain crystal symmetry. Such engineered domain structures in certain ferroelectric materials have been proven to give superior piezoelectric properties and extremely soft shear moduli. The objective of this article is to consider the variety of symmetries that can be produced through domain average engineering in proper ferroelectric systems arising from the cubic Pm[overline 3]m symmetry perovskite structure.

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Trust Negotiation For Authentication And Authorization In Healthcare Information Systems, Charles D. Knutson, Kent E. Seamons, Tore L. Sundelin, David K. Vawdrey Sep 2003

Trust Negotiation For Authentication And Authorization In Healthcare Information Systems, Charles D. Knutson, Kent E. Seamons, Tore L. Sundelin, David K. Vawdrey

Faculty Publications

The expanding availability of health information in an electronic format is strategic for industry-wide efforts to improve the quality and reduce the cnst of health care. The implementation of electronic medical record systems has been hindered by inadequate security provisions. This paper describes the use of frust negotiation as a framework for providing authentication and access control services in healthcare information systems. nust negotiation enables two parties with no pre-existing relationship to establish the trust necessary to perform sensitive transactions via the mutual disclosure of attributes contained within digital credentials. An extension of this system, surrogate irusf negoikiion is introduced …

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Schema Matching And Data Extraction Over Html Tables, Cui Tao Sep 2003

Schema Matching And Data Extraction Over Html Tables, Cui Tao

Theses and Dissertations

Data on the Web in HTML tables is mostly structured, but we usually do not know the structure in advance. Thus, we cannot directly query for data of interest. We propose a solution to this problem for the case of mostly structured data in the form of HTML tables, based on document-independent extraction ontologies. The solution entails elements of table location and table understanding, data integration, and wrapper creation. Table location and understanding allows us to locate the table of interest, recognize attributes and values, pair attributes with values, and form records. Data-integration techniques allow us to match source records …

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Target Sets: A Tool For Understanding And Predicting The Behavior Of Interacting Q-Learners, Nancy Fulda, Dan A. Ventura Sep 2003

Target Sets: A Tool For Understanding And Predicting The Behavior Of Interacting Q-Learners, Nancy Fulda, Dan A. Ventura

Faculty Publications

Reinforcement learning agents that interact in a common environment frequently affect each others’ perceived transition and reward distributions. This can result in convergence of the agents to a sub-optimal equilibrium or even to a solution that is not an equilibrium at all. Several modifications to the Q-learning algorithm have been proposed which enable agents to converge to optimal equilibria under specified conditions. This paper presents the concept of target sets as an aid to understanding why these modifications have been successful and as a tool to assist in the development of new modifications which are applicable in a wider range …

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Modular Verification Of Timed Circuits Using Automatic Abstraction, Eric G. Mercer, Chris Myers, Hao Zheng Sep 2003

Modular Verification Of Timed Circuits Using Automatic Abstraction, Eric G. Mercer, Chris Myers, Hao Zheng

Faculty Publications

The major barrier that prevents the application of formal verification to large designs is state explosion. This paper presents a new approach for verification of timed circuits using automatic abstraction. This approach partitions the design into modules, each with constrained complexity. Before verification is applied to each individual module, irrelevant information to the behavior of the selected module is abstracted away. This approach converts a verification problem with big exponential complexity to a set of subproblems, each with small exponential complexity. Experimental results are promising in that they indicate that our approach has the potential of completing much faster while …

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Interactive Level-Set Smoothing For Photo Editing, Thomas C. Howard, Bryan S. Morse Sep 2003

Interactive Level-Set Smoothing For Photo Editing, Thomas C. Howard, Bryan S. Morse

Faculty Publications

This paper presents an interactive image-smoothing tool based on properties and manipulation of image level sets. This tool uses PDE-based level-set smoothing to preserve edge sharpness while smoothing noise and jagged contours. Unlike existing approaches using PDEs, the duration and areas of application are controlled interactively with immediate feedback to the user. Interaction issues are addressed, and parameters for adjusting the PDE are automatically estimated based on image characteristics.

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Dynamic Sociometry In Particle Swarm Optimization, Mark Richards, Dan A. Ventura Sep 2003

Dynamic Sociometry In Particle Swarm Optimization, Mark Richards, Dan A. Ventura

Faculty Publications

The performance of Particle Swarm Optimization is greatly affected by the size and sociometry of the swarm. This research proposes a dynamic sociometry, which is shown to be more effective on some problems than the standard star and ring sociometries. The performance of various combinations of swarm size and sociometry on six different test functions is qualitatively analyzed.

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First-Principles Calculations For Nitrogen-Containing Single-Walled Carbon Nanotubes, James P. Lewis, Mingwen Zhao, Yueyugan Xia, Ruiqin Zhang Aug 2003

First-Principles Calculations For Nitrogen-Containing Single-Walled Carbon Nanotubes, James P. Lewis, Mingwen Zhao, Yueyugan Xia, Ruiqin Zhang

Faculty Publications

We present calculations for possible configurations of nitrogen-containing single-walled carbon nanotubes and their electronic properties obtained with the ab initio tight-binding FIREBALL method. It is found that nitrogen atoms can be energetically incorporated into the carbon network in three forms: Substitution, substitution with formation of a vacancy structure, and chemical adsorption. The different forms exhibit different local densities of states near the Fermi levels, which might suggest a potential method to control the electronic properties of nitrogen-doped carbon nanotubes

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Just-In-Time Browsing For Digitized Microfilm And Other Similar Image Collections, William A. Barrett, Douglas J. Kennard Aug 2003

Just-In-Time Browsing For Digitized Microfilm And Other Similar Image Collections, William A. Barrett, Douglas J. Kennard

Faculty Publications

This paper describes “Just-In-Time Browsing” (JITB), a method for image browsing (at modem-like speed) in which image data is transmitted and presented to the user progressively, in prioritized order, based on image content and user interaction. Spatial resolution and grayscale or color fidelity is increased first for the portions of the image that are immediately of most interest to the user. JITB is specifically geared toward digitized microfilm and other similar document image collections, although it can also be used for other types of images. A series of common browsing tasks performed by multiple users demonstrates that JITB compares favorably …

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Learning Real-Time A* Path Planner For Sensing Closely-Spaced Targets From An Aircraft, Jason K. Howlett, Michael A. Goodrich, Timothy W. Mclain Aug 2003

Learning Real-Time A* Path Planner For Sensing Closely-Spaced Targets From An Aircraft, Jason K. Howlett, Michael A. Goodrich, Timothy W. Mclain

Faculty Publications

This work develops an any-time path planner, based on the learning real-time A* (LRTA*) search, for generating flyable paths that allow an aircraft with a specified sensor footprint to sense a group of closely-spaced targets. The LRTA* algorithm searches a tree of flyable paths for the branch that accomplishes the desired objectives in the shortest distance. The tree of paths is created by assembling primitive turn and straight sections of a specified step size. The operating parameters for the LRTA* search directly influence the running time and path-length performance of the search. A modified LRTA* search is presented that terminates …

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Consensus-Based Table Form Recognition, William A. Barrett, Heath E. Nielson Aug 2003

Consensus-Based Table Form Recognition, William A. Barrett, Heath E. Nielson

Faculty Publications

Zoning documents increases the resolution of indexing from the image level to the field level. A line-delimited tabular document forms a well defined series of regions. However, as image quality decreases, accurate zoning becomes increasingly difficult. Given a sequence of documents with the same layout, we present a robust zoning method which exploits both intra- and inter-document consensus to form a more accurate combined result (template) that can be applied to any other document with the same layout.

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T-Splines And T-Nurccs, Thomas W. Sederberg, Jianmin Zheng, Almaz Bakenov, Ahmad Nasri Jul 2003

T-Splines And T-Nurccs, Thomas W. Sederberg, Jianmin Zheng, Almaz Bakenov, Ahmad Nasri

Faculty Publications

This paper presents a generalization of non-uniform B-spline surfaces called T-splines. T-spline control grids permit T-junctions, so lines of control points need not traverse the entire control grid. T-splines support many valuable operations within a consistent framework, such as local refinement, and the merging of several B-spline surfaces that have different knot vectors into a single gap-free model. The paper focuses on T-splines of degree three, which are C2 (in the absence of multiple knots). T-NURCCs (Non-Uniform Rational Catmull-Clark Surfaces with T-junctions) are a superset of both T-splines and Catmull-Clark surfaces. Thus, a modeling program for T-NURCCs can handle any …

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Multienergetic External-Beam Pixe As A Means Of Stydying The Surface Enrichment Effect In Coins, Scott Evans Perry Jul 2003

Multienergetic External-Beam Pixe As A Means Of Stydying The Surface Enrichment Effect In Coins, Scott Evans Perry

Theses and Dissertations

This thesis paper examines the feasibility of using external-beam PIXE to study the surface enrichment effect in metal artifacts. By varying the energy of the incident proton beam, we penetrated the artifact's surface to different levels and were able to produce a depth profile of the elemental composition of the sample. In this study, the sample set we chose to examine consisted of ancient and modern coins. This paper first describes the surface enrichment effect and theoretically how PIXE can be used to study it. It then details the construction of the components of the external-beam setup. Many of the …

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Observation Of And Model For Nonlinear Mode Conversion In A Non-Neutral Plasma, Grant W. Hart, Bryan G. Peterson, Ross L. Spencer Jul 2003

Observation Of And Model For Nonlinear Mode Conversion In A Non-Neutral Plasma, Grant W. Hart, Bryan G. Peterson, Ross L. Spencer

Faculty Publications

The nonlinear interaction of the two lowest Trivelpiece-Gould modes in a non-neutral plasma has been observed. Because of coupling in the nonlinear terms of the continuity and momentum equations, the two modes can exchange energy and convert one to the other. This can be modeled using the cold fluid equations and the averaging method. Experimentally, this process always stops with the lower frequency mode dominating the final state. Numerical integration of the model suggests that this occurs because the higher frequency mode is more strongly damped than the lower frequency mode.

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Iteration Methods For Approximating The Lowest Order Energy Eigenstate Of A Given Symmetry For One- And Two-Dimensional Systems, Chad Everett Junkermeier Jun 2003

Iteration Methods For Approximating The Lowest Order Energy Eigenstate Of A Given Symmetry For One- And Two-Dimensional Systems, Chad Everett Junkermeier

Theses and Dissertations

Using the idea that a quantum mechanical system drops to its ground state as its temperature goes to absolute zero several operators are devised to enable the approximation of the lowest order energy eigenstate of a given symmetry; as well as an approximation to the energy eigenvalue of the same order.

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Minimal Graphs In R3 Over Convex Domains, Michael Dorff Jun 2003

Minimal Graphs In R3 Over Convex Domains, Michael Dorff

Faculty Publications

Krust established that all conjugate and associate surfaces of a minimal graph over a convex domain are also graphs. Using a convolution theorem from the theory of harmonic univalent mappings, we generalize Krust's theorem to include the family of convolution surfaces which are generated by taking the Hadamard product or convolution of mappings. Since this convolution involves convex univalent analytic mappings, this family of convolution surfaces is much larger than just the family of associated surfaces. Also, this generalization guarantees that all the resulting surfaces are over close-toconvex domains. In particular, all the associate surfaces and certain Goursat transformation surfaces …

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The Topology Of Hyperbolic Attractors On Compact Surfaces, Todd L. Fisher Jun 2003

The Topology Of Hyperbolic Attractors On Compact Surfaces, Todd L. Fisher

Faculty Publications

Suppose M is a compact surface and M is a nontrivial mixing hyperbolic attractor for some f 2 Diff(M). We show that if is a hyperbolic set for some g 2 Diff(M), then is a nontrivial mixing hyperbolic attractor or repeller for g.

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A Self-Adapting Healthcare Information Infrastructure Using Mobile Computing Devices, James K. Archibald, Eric S. Hall, Charles D. Knutson, David K. Vawdrey Jun 2003

A Self-Adapting Healthcare Information Infrastructure Using Mobile Computing Devices, James K. Archibald, Eric S. Hall, Charles D. Knutson, David K. Vawdrey

Faculty Publications

Despite recent improvements in the gathering and sharing of patient medical information among healthcare providers, there remains a gap in the electronic medical record infrastructure. Patient data is not available in some situations, either because the infrastructure is inaccessible (as in a natural disaster) or because there is no way to link the patient to the infrastructure (e.g., the patient cannot supply necessary identification information). This paper describes the Poket Doktor System, an architecture that allows an individual to carry personal electronic medical information on a wireless handheld device such as a smart card, cell phone, or PDA. Medical workers …

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Dynamic Joint Action Perception For Q-Learning Agents, Nancy Fulda, Dan A. Ventura Jun 2003

Dynamic Joint Action Perception For Q-Learning Agents, Nancy Fulda, Dan A. Ventura

Faculty Publications

Q-learning is a reinforcement learning algorithm that learns expected utilities for state-action transitions through successive interactions with the environment. The algorithm's simplicity as well as its convergence properties have made it a popular algorithm for study. However, its non-parametric representation of utilities limits its effectiveness in environments with large amounts of perceptual input. For example, in multiagent systems, each agent may need to consider the action selections of its counterparts in order to learn effective behaviors. This creates a joint action space which grows exponentially with the number of agents in the system. In such situations, the Q-learning algorithm quickly …

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Knot Intervals And Multi-Degree Splines, Thomas W. Sederberg, Jianmin Zheng, Xiaowen Song May 2003

Knot Intervals And Multi-Degree Splines, Thomas W. Sederberg, Jianmin Zheng, Xiaowen Song

Faculty Publications

This paper studies the merits of using knot interval notation for B-spline curves, and presents formulae in terms of knot intervals for common B-spline operations such as knot insertion, differentiation, and degree elevation. Using knot interval notation, the paper introduces MD-splines, which are B-spline-like curves that are comprised of polynomial segments of various degrees (MD stands for \multi-degree"). MD-splines are a generalization of B-spline curves in that if all curve segments in an MD-spline have the same degree, it reduces to a B-spline curve. The paper focuses on MD-splines of degree 1, 2, and 3, as well as degree 1 …

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A Noise Filtering Method Using Neural Networks, Tony R. Martinez, Xinchuan Zeng May 2003

A Noise Filtering Method Using Neural Networks, Tony R. Martinez, Xinchuan Zeng

Faculty Publications

During the data collecting and labeling process it is possible for noise to be introduced into a data set. As a result, the quality of the data set degrades and experiments and inferences derived from the data set become less reliable. In this paper we present an algorithm, called ANR (automatic noise reduction), as a filtering mechanism to identify and remove noisy data items whose classes have been mislabeled. The underlying mechanism behind ANR is based on a framework of multi-layer artificial neural networks. ANR assigns each data item a soft class label in the form of a class probability …

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Simplifying Ocr Neural Networks With Oracle Learning, Tony R. Martinez, Joshua Menke May 2003

Simplifying Ocr Neural Networks With Oracle Learning, Tony R. Martinez, Joshua Menke

Faculty Publications

Often the best model to solve a real world problem is relatively complex. The following presents oracle learning, a method using a larger model as an oracle to train a smaller model on unlabeled data in order to obtain (1) a simpler acceptable model and (2) improved results over standard training methods on a similarly sized smaller model. In particular, this paper looks at oracle learning as applied to multi-layer perceptrons trained using standard backpropagation. For optical character recognition, oracle learning results in an 11.40% average decrease in error over direct training while maintaining 98.95% of the initial oracle accuracy.

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Decay Of Trapped-Particle Asymmetry Modes In Non-Neutral Plasmas In A Malmberg-Penning Trap, Grant W. Mason May 2003

Decay Of Trapped-Particle Asymmetry Modes In Non-Neutral Plasmas In A Malmberg-Penning Trap, Grant W. Mason

Faculty Publications

The mechanism for the strong damping of diocotron-like azimuthal trapped-particle asymmetry modes in a Malmberg-Penning trap is investigated with a detailed three-dimensional particle-in-cell computer simulation. The m = 1,kzis not equal to 0 modes are created by a voltage squeeze from a mid-detector ring followed by a displacement of trapped particles in opposite directions on either side of the ring. The voltage squeeze creates a population of particles confined to half the trap length (trapped) and a population of particles that move longitudinally along the full length of the cylinder (untrapped). The damping of the modes is found to be …

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Model-Based Human-Centered Task Automation: A Case Study In Acc System Design, Michael A. Goodrich, Erwin R. Boer May 2003

Model-Based Human-Centered Task Automation: A Case Study In Acc System Design, Michael A. Goodrich, Erwin R. Boer

Faculty Publications

Engineers, business managers, and governments are increasingly aware of the importance and difficulty of integrating technology and humans. The presence of technology can enhance human comfort, efficiency, and safety, but the absence of human factors analysis can lead to uncomfortable, inefficient, and unsafe systems. Systematic human-centered design requires a basic understanding of how humans generate and manage tasks. A very useful model of human behavior generation can be obtained by recognizing the task-specific role of mental models in not only guiding execution of skills but also managing initiation and termination of these skills. By identifying the human operator’s mental models …

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Enabling Remote Access To Personal Electronic Medical Records, James K. Archibald, Eric S. Hall, Charles D. Knutson, David K. Vawdrey May 2003

Enabling Remote Access To Personal Electronic Medical Records, James K. Archibald, Eric S. Hall, Charles D. Knutson, David K. Vawdrey

Faculty Publications

Millions of people suffer from medical conditions that should be made known to healthcare practitioners prior to treatment. Paramedics and emergency room doctors cannot provide optimal care without sufficient knowledge of a patient’s medical history. Lacking patient information such as allergies, current prescriptions, and preexisting conditions, medical professionals are often forced to either delay treatment or rely on instincts. Medical mistakes in situations like these kill thousands of people and cost an estimated US$37 billion each year in the United States [1]. With the advent of electronic medical records (EMRs), patient information can be stored in computer databases at hospitals …

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