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Iowa State University

2002

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An Inexpensive, Accurate Method For Measuring Leaf Area And Defoliation Through Digital Image Analysis, Matthew E. O'Neal, Douglas A. Landis, Rufus Isaacs Dec 2002

An Inexpensive, Accurate Method For Measuring Leaf Area And Defoliation Through Digital Image Analysis, Matthew E. O'Neal, Douglas A. Landis, Rufus Isaacs

Matthew E. O'Neal

We report a protocol using a common desk-top scanner and public domain software for measuring existing leaf area and leaf area removed as a result of herbivory. We compared the accuracy and precision of this method to that of a standard leaf area meter. Both methods were used to measure metal disks of a known area, the area of soybean (Glycine max L.) leaves, and the area removed by simulating leaf feeding with a hole-punch. We varied the amount of injury across a low, medium, and high degree of simulated feeding. The mean area of 10 cm2 and 50 cm2 …

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A Coverage Model For Topology Design In Wireless Mesh Networks, Kevin P. Scheibe Nov 2002

A Coverage Model For Topology Design In Wireless Mesh Networks, Kevin P. Scheibe

Kevin P. Scheibe

During the last five years, mesh networks have emerged as a promising new technology for fixed wireless radio data networks. Mesh networks differ from traditional wireless radio networks in that customer nodes serve as part of the network backbone by relaying messages from other customers. However, given the high frequency of mesh radio transmitters necessary to provide sufficient data rates, these systems operate by line-of-sight. Thus, the ability to connect random subscriber locations is a major issue. While a few companies have developed systems using mesh technology, all algorithms for topology design appear to be proprietary leaving little if anything …

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Assessment Of Concentrated Flow Through Riparian Buffers, Michael G. Dosskey, Matthew J. Helmers, Dean E. Eisenhauer, Thomas G. Franti, Kyle D. Hoagland Nov 2002

Assessment Of Concentrated Flow Through Riparian Buffers, Michael G. Dosskey, Matthew J. Helmers, Dean E. Eisenhauer, Thomas G. Franti, Kyle D. Hoagland

Matthew J. Helmers

Concentrated flow of surface runoff from agricultural fields may limit the capability of riparian buffers to remove pollutants. This study was conducted on four farms in southeastern Nebraska to develop a method for assessing the extent of concentrated flow in riparian buffers and for evaluating the impact that it has on sediment-trapping efficiency. Field methods consisted of mapping field runoff areas and their pathways to and through riparian buffers to streams. Mathematical relationships were developed from a model (VFSMOD) that estimates sediment-trapping efficiency from the ratio of buffer area to field runoff area. Among the farms surveyed, riparian buffers averaged …

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Stationary Correlations For A Far-From-Equilibrium Spin Chain, Beate Schmittmann, F. Schmüser Oct 2002

Stationary Correlations For A Far-From-Equilibrium Spin Chain, Beate Schmittmann, F. Schmüser

Beate Schmittmann

A kinetic one-dimensional Ising model on a ring evolves according to a generalization of Glauber rates, such that spins at even (odd) lattice sites experience a temperature Te (To). Detailed balance is violated so that the spin chain settles into a nonequilibrium stationary state, characterized by multiple interactions of increasing range and spin order. We derive the equations of motion for arbitrary correlation functions and solve them to obtain an exact representation of the steady state. Two nontrivial amplitudes reflect the sublattice symmetries; otherwise, correlations decay exponentially, modulo the periodicity of the ring. In the long-chain limit, they factorize into …

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Systematic Microstructure Variability In Double-Diffusively Stable Coastal Waters Of Nonuniform Density Gradient, Timothy F. Duda, Chris R. Rehmann Oct 2002

Systematic Microstructure Variability In Double-Diffusively Stable Coastal Waters Of Nonuniform Density Gradient, Timothy F. Duda, Chris R. Rehmann

Chris R. Rehmann

Conductivity microstructure, water velocity, and stratification were measured during a tow-yo transect near the New England shelf/slope front in early August 1997. Velocity data were collected with an acoustic Doppler profiler on the ship. The other data were collected with a towed platform. Estimates of χ, the rate of dissipation of temperature variance, were computed from the conductivity data with vertical resolution of 0.3 m. Relationships between χ and shear, temperature gradient, buoyancy frequency (N), and gradient Richardson number (Ri) were explored, with special focus on measurements taken in waters stable to double-diffusive processes (to avoid ambiguity of interpretation) and …

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Time Management—A Design-Build Builder's Perspective, Srinath Pai Kasturi, Douglas D. Gransberg Sep 2002

Time Management—A Design-Build Builder's Perspective, Srinath Pai Kasturi, Douglas D. Gransberg

Douglas D. Gransberg

Time management in design-build construction encompasses efficient project management controls, scheduling and execution of the contract as agreed upon by the parties. Time management is one of the prime areas of concern to the builder and his team. It plays an important role in shaping the progress of projects and thus is decisive in determining its course. This article explains the importance of time management in construction. Time management techniques on a (builder prime, architect subcontract) design build project from a builders perspective are presented. The builder ideally has to prioritize his tasks based on the resources and manpower of …

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Path Dependence And The Origins Of Cotton Textile Manufacturing In New England, Joshua L. Rosenbloom Sep 2002

Path Dependence And The Origins Of Cotton Textile Manufacturing In New England, Joshua L. Rosenbloom

Joshua L. Rosenbloom

During the first half of the nineteenth century the United States emerged as a major producer of cotton textiles. This paper argues that the expansion of domestic textile production is best understood as a path-dependent process that was initiated by the protection provided by the Embargo Act of 1807 and the War of 1812. This initial period of protection ended abruptly in 1815 with the conclusion of the war and the resumption of British imports, but the political climate had been irreversibly changed by the temporary expansion of the industry. After 1815 nascent manufacturers sought to protect the investments they …

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Hydrophobic Probe Binding Of Β-Lactoglobulin In The Native And Molten Globule State Induced By High Pressure As Affected By Ph, Kio3 And N-Ethylmaleimide, Jian Yang, Joseph R. Powers, Stephanie Clark, A. Keith Dunker, Barry G. Swanson Aug 2002

Hydrophobic Probe Binding Of Β-Lactoglobulin In The Native And Molten Globule State Induced By High Pressure As Affected By Ph, Kio3 And N-Ethylmaleimide, Jian Yang, Joseph R. Powers, Stephanie Clark, A. Keith Dunker, Barry G. Swanson

Stephanie Clark

High hydrostatic pressure (HHP) at 500 MPa and 50 °C induces β-LG into the molten globule state. Retinol, cis-parinaric acid (CPA), and 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence from pH 2.5 to 10.5 in the presence of the native and molten globule states of β-LG indicate that retinol binds to β-LG in the calyx, CPA at the surface hydrophobic site, and ANS in multiple hydrophobic sites. HHP treatment results in a decrease of β-LG affinity for retinol and CPA, suggesting conformational changes in the calyx and surface hydrophobic site of β-LG during HHP treatment. β-LG treated by HHP in the presence of N-ethylmaleimide …

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Jun Dimerization Protein 2 Functions As A Progesterone Receptor N-Terminal Domain Coactivator, James S. Adelman, Suzanne E. Wardell, Viroj Boonyaratanakornkit, Ami Aronheim Aug 2002

Jun Dimerization Protein 2 Functions As A Progesterone Receptor N-Terminal Domain Coactivator, James S. Adelman, Suzanne E. Wardell, Viroj Boonyaratanakornkit, Ami Aronheim

James S. Adelman

The progesterone receptor (PR) contains two transcription activation function (AF) domains, constitutive AF-1 in the N terminus and AF-2 in the C terminus. AF-2 activity is mediated by a hormone-dependent interaction with a family of steroid receptor coactivators (SRCs). SRC-1 can also stimulate AF-1 activity through a secondary domain that interacts simultaneously with the primary AF-2 interaction site. Other protein interactions and mechanisms that mediate AF-1 activity are not well defined. By interaction cloning, we identified an AP-1 family member, Jun dimerization protein 2 (JDP-2), as a novel PR-interacting protein. JDP-2 was first defined as a c-Jun interacting protein that …

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Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates Aug 2002

Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates

Eric W. Cochran

We report the temperature dependence of the Flory-Huggins interaction parameter for three symmetric diblock copolymer systems containing poly(cyclohexylethylene) (PCHE): poly(cyclohexylethylene-b-ethylene) (CE), poly(cyclohexylethylene-b-ethylethylene) (CEE), and poly(cyclohexylethylene-b-ethylenepropylene) (CP). Order-disorder transition temperatures (TODT) were determined using dynamic mechanical spectroscopy and interpreted with mean-field theory, (χN)ODT = 10.5, leading to well-defined expressions for χ(T). These results have been analyzed in the context of solubility parameter (δ) theory resulting in a unique parameter δC that describes the interactions in CE, CP, and CEE, where δC < δEE < δP < δE with (δE - δC) ≈ 1.6 MPa1/2 at 500 K. In contrast to the predictions of group contribution theory, this indicates that δC is in surprisingly close proximity to the solubility parameter for poly(dimethylsiloxane).

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Magnetochemical Origin For Invar Anomalies In Iron-Nickel Alloys, V. Crisan, P. Entel, H. Ebert, H. Akai, Duane D. Johnson, J. B. Staunton Jul 2002

Magnetochemical Origin For Invar Anomalies In Iron-Nickel Alloys, V. Crisan, P. Entel, H. Ebert, H. Akai, Duane D. Johnson, J. B. Staunton

Duane D. Johnson

Zero- and finite-temperature (T) first-principles calculations versus composition (c) show that magnetochemical effects lead to Invar anomalies in Fe-(Ni, Co, Pt) alloys. Chemical short- or long-range order and negative interatomic exchange interaction of electrons in antibonding majority-spin states force the face-centered-cubic lattice to compete simultaneously for a smaller volume (from antiferromagnetic tendencies) and a larger volume (from Stoner ferromagnetic tendencies). The resulting additional negative lattice anharmonicity is very large for Fe-(Ni, Co) while absent for Fe-Pt. Our results explain the T- and c-dependent behavior of Invar properties, including the lattice softening and thermal expansion of Fe-Ni. In addition, the occurrence …

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Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy L. Kaleita, Mukti Singh Jul 2002

Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy L. Kaleita, Mukti Singh

Amy L. Kaleita

Aerial hyperspectral imagery has potential for agriculture applications. The objective of this study is to identify significant wavelength ranges (image bands or band combinations) from hyperspectral imagery for different field information extraction. The field information include corn nitrogen content, plant population, yield, and grain quality such as oil, protein, and extractable starch. All the images were processed using the GA-SPCA (Genetic Algorithm based Selective Principal Component Analysis) method . T he GA-SPCA method can filter out significant image bands and reduce the image data dimension to only one principle component image through a cascade two-step dimension reduction process. It was …

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Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei F. Tian Jul 2002

Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei F. Tian

Amy L. Kaleita

A methodology for assessing distributed surface soil moisture content from optical remote sensing is developed. This study uses both ground-based and remotely sensed spectral measurements of soil reflectance in visible and near-infrared wavelengths and concurrent measurements of volumetric soil moisture within the top 6 cm to establish a relationship between spectral response and moisture. Various approaches, including principal component analyses and regression techniques are investigated to determine the potential for quantifying soil moisture from the spectral reflection data. Preliminary investigations have yielded R 2 values as high as 0.62 when comparing predictions to actual moisture values. Investigation of predicting soil …

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Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei Tian Jul 2002

Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei Tian

Amy L. Kaleita

A methodology for assessing distributed surface soil moisture content from optical remote sensing is developed. This study uses both ground-based and remotely sensed spectral measurements of soil reflectance in visible and near-infrared wavelengths and concurrent measurements of volumetric soil moisture within the top 6 cm to establish a relationship between spectral response and moisture. Various approaches, including principal component analyses and regression techniques are investigated to determine the potential for quantifying soil moisture from the spectral reflection data. Preliminary investigations have yielded R 2 values as high as 0.62 when comparing predictions to actual moisture values. Investigation of predicting soil …

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Screening For Volatile Fatty Acids In Agricultural Air Using Solid Phase Microextraction And Gas Chromatography – Mass Spectrometry, Jarett P. Spinhirne, Jacek A. Koziel, David B. Parker, Darren L. Williams, N. Andy Cole, John M. Sweeten Jul 2002

Screening For Volatile Fatty Acids In Agricultural Air Using Solid Phase Microextraction And Gas Chromatography – Mass Spectrometry, Jarett P. Spinhirne, Jacek A. Koziel, David B. Parker, Darren L. Williams, N. Andy Cole, John M. Sweeten

Jacek A. Koziel

Volatile fatty acids (VFAs) are a major component of odorous gases associated with agricultural sources. Because of typically low VFA air concentrations, conventional air sampling methods including sorbent tubes and vacuum canisters are often not sensitive enough to detect them. Solid phase microextraction (SPME) was used in this research because it is very sensitive, reusable, fast, and combines sampling and sample preparation, allowing for rapid detection of low concentrations of organics in air. This research focused on 7 VFAs: acetic, propionic, isobutyric, butyric, isovaleric, valeric, and hexanoic acids. Field experiments were conducted to test this method for air sampling of …

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Noninvasive Sampling And Analysis Of Bovine Breath Using Solid-Phase Microextraction And Gas Chromatography-Mass Spectrometry: A Feasibility Study, Jacek A. Koziel, Jarett P. Spinhirne, Norbert K. Chirase Jul 2002

Noninvasive Sampling And Analysis Of Bovine Breath Using Solid-Phase Microextraction And Gas Chromatography-Mass Spectrometry: A Feasibility Study, Jacek A. Koziel, Jarett P. Spinhirne, Norbert K. Chirase

Jacek A. Koziel

An experiment was conducted to examine the feasibility of detecting unique volatile organic biomarkers exhaled by healthy and morbid heifer calves on-site using noninvasive sampling with solid phase microextraction (SPME) and analysis with gas chromatography-mass spectrometry (GC-MS). Two heifers were selected on the bases of health status and were sampled from 5 to 15 min with a special facemask sampling system using DVB/Carboxen/PDMS 50/30 µ m and PDMS 100 µ m SPME fibers. The samples were sealed and transported to the laboratory and analyzed with ion trap GC-MS. Acetone, methyl ethyl ketone, toluene, pentadecane, and nonanal were detected in cattle …

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Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy Kaleita, Mukti Singh Jul 2002

Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy Kaleita, Mukti Singh

Amy L. Kaleita

Aerial hyperspectral imagery has potential for agriculture applications. The objective of this study is to identify significant wavelength ranges (image bands or band combinations) from hyperspectral imagery for different field information extraction. The field information include corn nitrogen content, plant population, yield, and grain quality such as oil, protein, and extractable starch. All the images were processed using the GA-SPCA (Genetic Algorithm based Selective Principal Component Analysis) method . T he GA-SPCA method can filter out significant image bands and reduce the image data dimension to only one principle component image through a cascade two-step dimension reduction process. It was …

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An Overland Flow Sampler For Use In Vegetative Filters, D. Eisenhauer, Matthew J. Helmers, J. Brothers, M. Dosskey, T. Franti, A. Boldt, B. Strahm Jul 2002

An Overland Flow Sampler For Use In Vegetative Filters, D. Eisenhauer, Matthew J. Helmers, J. Brothers, M. Dosskey, T. Franti, A. Boldt, B. Strahm

Matthew J. Helmers

Vegetative filters (VF) are used to remove contaminants from agricultural runoff and improve surface water quality. State and federal cost-share funds are available to encourage landowners to install VF. The USDA-National Conservation Buffer Initiative calls for 3.2 million km of buffers to be installed by the year 2002. Numerous experimental plot and modeling studies have quantified the removal of sediments and other non-point source (NPS) contaminants from agricultural runoff by VF. Almost all of these studies have been conducted under controlled settings, including artificial sheet flow conditions, and using expensive, labor-intensive measurement systems. There is a critical need for simple, …

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Leading Organizational Change: A Comparison Of County And Campus Views Of Extension Engagement, Nancy K. Franz, Randall S. Peterson, Amber L. Dailey Jun 2002

Leading Organizational Change: A Comparison Of County And Campus Views Of Extension Engagement, Nancy K. Franz, Randall S. Peterson, Amber L. Dailey

Nancy K. Franz

Feeling pressure from stakeholders, Cornell Cooperative Extension has responded using the Kellogg Commission report on the Future of State and Land-Grant Universities as a blueprint for organizational change. Results of interviews revealed both similarities and differences in county and state staff views of engagement. The most significant difference is that county staff view their jobs as the critical link between community needs and university resources, while campus staff view them as implementers of programs. This finding suggests a need to engage all staff in a mutual dialogue of roles and expectation if change based on Extension engagement is to be …

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Mechanism Of Abietadiene Synthase Catalysis: Stereochemistry And Stabilization Of The Cryptic Pimarenyl Carbocation Intermediates, Reuben J. Peters, Matthew M. Ravn, Robert M. Coates, Rodney Croteau Jun 2002

Mechanism Of Abietadiene Synthase Catalysis: Stereochemistry And Stabilization Of The Cryptic Pimarenyl Carbocation Intermediates, Reuben J. Peters, Matthew M. Ravn, Robert M. Coates, Rodney Croteau

Reuben J. Peters

Abietadiene synthase (AS) catalyzes the complex cyclization-rearrangement of (E,E,E)-geranylgeranyl diphosphate (8, GGPP) to a mixture of abietadiene (1a), double bond isomers 2a-4a and pimaradienes 5a-7a as a key step in the biosynthesis of the abietane resin acid constituents (1b-4b) of conifer oleoresin. The reaction proceeds at two active sites by way of the intermediate, copalyl diphosphate (9). In the second site, a putative tricyclic pimaradiene or pimarenyl(+) carbocation intermediate of undefined C13 stereochemistry and annular double bond position is formed. Three 8-oxy-17-nor analogues of 9 (17 and 19a,b) and three isomeric 15,16-bisnorpimarenyl-N-methylamines (26a-c) were synthesized and evaluated as alternative substrates …

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Review Of Groove Tube: The Revolution As It Was Televised, Barbara Ching Jun 2002

Review Of Groove Tube: The Revolution As It Was Televised, Barbara Ching

Barbara Ching

Groove Tube engagingly imparts a wealth of information about television programming and the American counterculture. Concentrating on the years 1966–1971, Bodroghkozy claims to “trace how . . . entertainment television engaged with manifestations of youth rebellion and dissent” (4). She analyzes television “as an institution, a body of texts, and a group of audiences” that entered a “crisis of authority” in this period (17). “During such a crisis,” she explains, “the ruling elites . . . can only dominate using coercive means rather than consensual methods” (16). Nevertheless, in the history Bodroghkozy sketches, the networks ultimately cobbled together a “hegemonic …

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Outcomes Assessment: Developing An Electronic Assessment Database As A Model For Collection And Analysis Of Data, Joni E. Spurlin, Sarah A. Rajala, Jerome P. Lavelle, O. Jerome Hoskins Jun 2002

Outcomes Assessment: Developing An Electronic Assessment Database As A Model For Collection And Analysis Of Data, Joni E. Spurlin, Sarah A. Rajala, Jerome P. Lavelle, O. Jerome Hoskins

Sarah A. Rajala

As the ABET process in each institution moves toward outcomes assessment, it pushes each program to develop and implement its outcome assessment plans. Assessment plans document how programs will gather data, interpret the findings, and use the results to make improvements in programs, curricula, and resources. The ABET team at North Carolina State University (faculty from each engineering discipline along with assessment-knowledgeable personnel) has developed a model that academic programs within the College of Engineering use to determine what data to gather, where to obtain the data, and what criteria may be most appropriate when interpreting the data. This paper …

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Width-Wise Variation Of Magnetic Tape Pack Stresses, Jonathan A. Wickert, Y.M. Lee May 2002

Width-Wise Variation Of Magnetic Tape Pack Stresses, Jonathan A. Wickert, Y.M. Lee

Jonathan A. Wickert

A model is developed for predicting the stress and displacement fields within a magnetic tape pack, where those quantities are allowed to vary in both the pack's radial and transverse (cross-tape) directions. As has been the case in previous analyses based upon one-dimensional wound roll models, the present approach accounts for the anisotropic and nonlinear constitutive properties of the layered tape, and the incremental manner in which the pack is wound. Further, such widthwise variation effects as differential hub compliance and nonuniform winding tension, which can be significant in data cartridge design, are also treated in the model. The pack …

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A Time-Resolved Method For Nonlinear Acoustic Measurement, Stephen D. Holland May 2002

A Time-Resolved Method For Nonlinear Acoustic Measurement, Stephen D. Holland

Stephen D. Holland

We describe a time-resolved method for measuring nonlinear ultrasonic phenomena. Conventional approaches to the measurement of nonlinear phenomena utilize narrowband measurements of harmonic generation. These measurements are fundamentally narrowband and hence have poor time resolution. In contrast, our method utilizes a series of narrowband bursts that can be combined to form a composite time-resolved broadband impulse. Simultaneous time resolution and harmonic isolation are thereby obtained. The composite impulse can then be used to perform time-resolved measurements of weakly nonlinear phenomena. Such time-resolved measurements have the potential to dramatically improve the capability and performance of nondestructive testing systems that use acoustic …

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Absolute Tin(111) Step Energies From Analysis Of Anisotropic Island Shape Fluctuations, S. Kodambaka, V. Petrova, S. V. Khare, Duane D. Johnson, I. Petrov, J. E. Greene Apr 2002

Absolute Tin(111) Step Energies From Analysis Of Anisotropic Island Shape Fluctuations, S. Kodambaka, V. Petrova, S. V. Khare, Duane D. Johnson, I. Petrov, J. E. Greene

Duane D. Johnson

In situ high-temperature (1165–1248 K) scanning tunneling microscopy was used to measure fluctuations around the equilibrium shape of two-dimensional vacancy islands on TiN(111) terraces. From the equilibrium shape, the ratio of the two ⟨110⟩ step energies was found to be 0.72±0.02. Combining this with the results of an exact approach for analysis of shape fluctuations, applicable to highly anisotropic islands, we obtain absolute values for step energies and step stiffnesses as a function of orientation.

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Complement Resistance, As Determined By Viable Count And Flow Cytometric Methods, And Its Association With The Presence Of Iss And The Virulence Of Avian Escherichia Coli, Lisa K. Nolan, Catherine W. Giddings, Shelley M. Horne, Curt Doetkott, Penelope S. Gibbs, Richard E. Wooley, Steven L. Foley Apr 2002

Complement Resistance, As Determined By Viable Count And Flow Cytometric Methods, And Its Association With The Presence Of Iss And The Virulence Of Avian Escherichia Coli, Lisa K. Nolan, Catherine W. Giddings, Shelley M. Horne, Curt Doetkott, Penelope S. Gibbs, Richard E. Wooley, Steven L. Foley

Lisa K. Nolan

Previous work in our labs has shown that avian Escherichia coli virulence is correlated with resistance to complement. Also, our studies have revealed that the presence of the increased serum survival gene (iss), known to contribute to the complement resistance and virulence of mammalian E. coli, may predict the virulent nature of an avian E. coli isolate. This relationship warrants further research, but further clarification of the relationship among virulence, complement resistance, and iss sequences requires use of complement susceptibility assays. Such assays, unfortunately, are labor-intensive, expensive, and difficult to perform. In the present study, the results of two complement …

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Location Of Increased Serum Survival Gene And Selected Virulence Traits On A Conjugative R Plasmid In An Avian Escherichia Coli Isolate, Timothy J. Johnson, Catherine W. Giddings, Shelley M. Horne, Penelope S. Gibbs, Richard E. Wooley, Jerod Skyberg, Pam Olah, Ronda Kercher, Julie S. Sherwood, Steven L. Foley, Lisa K. Nolan Apr 2002

Location Of Increased Serum Survival Gene And Selected Virulence Traits On A Conjugative R Plasmid In An Avian Escherichia Coli Isolate, Timothy J. Johnson, Catherine W. Giddings, Shelley M. Horne, Penelope S. Gibbs, Richard E. Wooley, Jerod Skyberg, Pam Olah, Ronda Kercher, Julie S. Sherwood, Steven L. Foley, Lisa K. Nolan

Lisa K. Nolan

Avian colibacillosis is a costly disease for the poultry industry. The mechanisms of virulence employed by the etiologic agent of this disease remain ill defined. However, accumulated evidence suggests that complement resistance and the presence of the increased serum survival gene (iss) in an avian Escherichia coli isolate may be indicative of its ability to cause disease. This association of iss with the E. coli implicated in avian disease may mean that iss and/or, perhaps, the genes associated with it are important contributors to avian E. coli virulence. For this reason, we have begun a search for iss's location in …

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Toward Improved Film Cooling Prediction, G. Medic, Paul A. Durbin Apr 2002

Toward Improved Film Cooling Prediction, G. Medic, Paul A. Durbin

Paul A. Durbin

Computations of flow and heat transfer for a film-cooled high pressure gas turbine rotor blade geometry are presented with an assessment of several turbulence models. Details of flow and temperature field predictions in the vicinity of cooling holes are examined. It is demonstrated that good predictions can be obtained when spurious turbulence energy production by the turbulence model is prevented.

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Toward Improved Prediction Of Heat Transfer On Turbine Blades, G. Medic, Paul A. Durbin Apr 2002

Toward Improved Prediction Of Heat Transfer On Turbine Blades, G. Medic, Paul A. Durbin

Paul A. Durbin

Reynolds averaged computations of turbulent flow in a transonic turbine passage are presented to illustrate a manner in which widely used turbulence models sometimes provide poor heat transfer predictions. It is shown that simple, physically and mathematically based constraints can substantially improve those predictions.

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Multipole Expansion Of Dislocation Interactions: Application To Discrete Dislocations, Richard Alan Lesar, J. M. Rickman Apr 2002

Multipole Expansion Of Dislocation Interactions: Application To Discrete Dislocations, Richard Alan Lesar, J. M. Rickman

Richard Alan Lesar

The interaction between dislocations is long ranged and anisotropic, leading to severe computational challenges for large-scale simulations. Here we present a multipolar expansion for the interaction energy between dislocations in three dimensions, based on a straightforward expansion of some familiar energy expressions. An evaluation of the needed line integrals is conveniently performed by numerical integration over parametric representations of the dislocation loops. We show that the multipole expansion converges very quickly, leading to potential savings in computational time for evaluating dislocation interactions.

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