Engineering Commons^™

Global Expression Profiling Of Acetate-Grown Escherichia Coli, Min-Kyu Oh, Lars Rohlin, Katy Kao, James Liao

Faculty Publications

This study characterized the transcript profile of Escherichia coli in acetate cultures using DNA microarray on glass slides. Glucose-grown cultures were used as a reference. At the 95% confidence level, 354 genes were up-regulated in acetate, while 370 genes were down-regulated compared with the glucose-grown culture. Generally, more metabolic genes were up-regulated in acetate than other gene groups, while genes involved in cell replication, transcription, and translation machinery tended to be down-regulated. It appears that E. coli commits more resources to metabolism at the expense of growth when cultured in the poor carbon source. The expression profile confirms many known …

Solitary Waves And Supersonic Reaction Front In Metastable Solids, Hendrik J. Viljoen, Lee L. Lauderback, Didier Sornette

Papers in Solid Phase Dynamics

Motivated by an increasing number of remarkable experimental observations on the role of pressure and shear stress in solid reactions, explosions, and detonations, we present a simple one-dimensional model that embodies nonlinear elasticity and dispersion as well as chemical or phase transformation. This generalization of the Toda lattice provides an effective model for the description of the organization during an abrupt transformation in a solid. One of the challenges is to capture both the equilibrium degrees of freedom as well as to quantify the possible role of out-of-equilibrium perturbations. In the Toda lattice, we verify that the particle velocities converge …

Two-Photon-Excited Green Emission And Its Dichroic Shift Of Oriented Thin-Film Cds On Glass Formed By Laser Deposition, B. Ullrich, R. Schroeder, H. Sakai, A. Zhang, Stephen Z. D. Cheng

College of Polymer Science and Polymer Engineering

The photoluminescence of oriented thin-film CdS on glass formed by laser deposition was investigated employing 200 fs, 1.54 eV laser pulses at room temperature. The ultrafast excitation caused a two-photon absorption process, which results in purely green emission at the band gap. The spectra are fitted very well by the application of the van Roosbroeck-Shockley relation, density of states, and Urbach's rule demonstrating the intrinsic character of the radiative recombination. It is further shown that the energy position of the emission peak depends on the polarization of the impinging laser beam due to the dichroism of the highly oriented films. …

Jan 2002, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Newsletter Report Museum Open House 149 visitors

Cxquery: A Novel Xml Query Language, Peter Revesz, Yi Chen

School of Computing: Conference and Workshop Papers

XML is becoming the data exchange standard on the Internet. Previously proposed XML query languages, such as XQuery, Quilt, YALT, Lorel, and XML-QL, lack schema definition of the query result; therefore, they are limited for defining views, integrating data, updating, and further querying, all of which are often needed in e-Business applications. We propose a novel XML query language called CXQuery, which defines the schema of the query results explicitly and can easily define views, and integrate, update, and query XML data. In addition, CXQuery can express spatial and spatio-temporal queries using a constraint-based querying approach.

Evaporation From Irrigated Agricultural Land In California, Charles M. Burt, Andrew Mutziger, Daniel Howes, Kenneth H. Solomon

BioResource and Agricultural Engineering

No abstract provided.

Variable Frequency Drives And Scada — Are They Worthwhile Investments?, Charles M. Burt, Daniel J. Howes

BioResource and Agricultural Engineering

Managers and personnel from five California irrigation districs were interviewed to determine if installing variable frequency drives (VFDs) and supervisory control and data acquisition (SCADA) systems were worthwhile investments.

Infrared Inspection, Charles M. Burt, Daniel J. Howes

BioResource and Agricultural Engineering

Infrared thermography is the use of infrared radiation to qualitatively and quantitatively express heat signatures and heat differences. Infrared inspection can help identify weak connections in an electrical box, uneven heating of pump windings, overheating of bearings, and many other possibly devastating problems well before any failure occurs. The use of thermography as a preventative tool can increase system reliability and efficiency.

Cable Barrier Literature Review, Brian A. Coon, Ronald K. Faller, John D. Reid

Mid-America Transportation Center: Final Reports and Technical Briefs

A literature review of cable barrier systems.

The Effect Of Broadleaf Canopies On Survey-Grade Horizontal Gps/Glonass Measurements, Thomas H. Meyer, John E. Bean, C. Roger Ferguson, James M. Naismith

Department of Natural Resources and the Environment Articles

A study was conducted to empirically determine the degradation of survey-grade GPS horizontal position measurements due to the effects of broadleaf forest canopies. The measurements were taken using GPS/GLONASS-capable receivers measuring C/A and P-codes, and carrier phase. Fourteen survey markers were chosen in central Connecticut to serve as reference markers for the study. These markers had varying degrees of sky obstruction due to overhanging tree canopies. Sky obstruction was measured by photographing the sky with a 35mm reflex camera fitted with a hemispherical lens. The negative was scanned and the image mapped using an equal- area projection to remove the …

The Prince William Sound Risk Assessment, Jason R. W. Merrick, Van Dorp Rene J., Thomas Mazzuchi, John R. Harrald, John E. Spahn, Martha Grabowski

Statistical Sciences and Operations Research Publications

After the grounding of the Exxon Valdez, and its subsequent oil spill, all parties with interests in Prince William Sound (PWS) were eager to prevent another major pollution event. While they implemented several measures to reduce the risk of an oil spill, the stakeholders disagreed about the effectiveness of these measures and the potential effectiveness of further proposed measures. They formed a steering committee to represent all the major stakeholders in the oil industry, in the government, in local industry and among the local citizens. The steering committee hired a consultant team, who created a detailed model of the PWS …

Detection Of Intensification Of The Global Water Cycle: The Potential Role Of Friend, Alan D. Zeigler, Justin Sheffield, Eric F. Wood, Bart Nijssen, Edwin P. Maurer, Dennis P. Lettenmaier

Civil, Environmental and Sustainable Engineering

Diagnostic studies of 14-year, 2 — 2°, Variable Infiltration Capacity (VIC) model off-line simulations of the global terrestrial water budget suggest that, given the annual variability in the major components of continental hydrological cycles (precipitation, evaporation, and runoff), several decades to perhaps centuries of measurements may be needed to detect with high confidence the intensification predicted by recent global climate model (GCM) studies simulating plausible global warming scenarios. Furthermore, these measurements may need to originate from a wider geographic expanse than is currently investigated within large-scale hydrological assessment programmes, such as the Global Energy and Water Experiment (GEWEX). Smaller, geographically …

Acuta Enews January 2002, Vol 31, No. 1

ACUTA Newsletters

In This Issue

Univ. of Wisconsin-Stout Wins Baldrige Award

Bringing New Members to ACUTA

DC Update

Managing the Cable Distribution Plant

What Are You Afraid Of? (Risk Analysis)

Board Report

New Members

Job Postings

Presented Antigen From Damaged Pancreatic Beta Cells Activates Autoreactive T Cells In Virus-Mediated Autoimmune Diabetes., Marc S. Horwitz, Alex Ilic, Cody Fine, Enrique Rodriguez, Nora Sarvetnick

Journal Articles: Regenerative Medicine

The induction of autoimmunity by viruses has been attributed to numerous mechanisms. In mice, coxsackievirus B4 (CB4) induces insulin-dependent diabetes mellitus (IDDM) resembling the final step of disease progression in humans. The immune response following the viral insult clearly precipitates IDDM. However, the molecular pathway between viral infection and the subsequent activation of T cells specific for islet antigen has not been elucidated. These T cells could become activated through exposure to sequestered antigens released by damaged beta cells, or they could have responded to factors secreted by the inflammatory response itself. To distinguish between these possibilities, we treated mice …

Comprehensive Subgrade Deflection Acceptance Criteria - Pilot Implementation Report, James Crovetti, Jay Schabelski

Transportation Research Center: Subgrade Deflection Studies

This report has presents the findings of implementations of pilot specifications for subgrade acceptance based on measured deflections. The reconfigured rolling wheel deflectomter (RWD), portable truck-mounted deflection measurement systems, and dynamic cone penetrometer (DCP) were utilized on four subgrade construction projects during the 2001 construction season. Comparative nuclear density readings were obtained at selected locations within each project. Comparative soil stiffness gauge readings were also obtained on 2 of the pilot projects

The research findings from this and previous study phases indicate that deflection test results may be appropriate for identifying areas of poor in-place stability within constructed subgrades. However, …

Two Charge States Of Dominant Acceptor In Unintentionally Doped Gan: Evidence From Photoluminescence Study, Michael A. Reshchikov, Hadis Morkoç, S. S. Park, K. Y. Lee

Electrical and Computer Engineering Publications

Photoluminescence of the dominant deep-level acceptor in high-purity freestanding GaN is studied over a wide range of excitation intensities. A yellow luminescence (YL) band at about 2.2 eV saturates with increasing excitation intensity, whereas a green luminescence (GL) band at about 2.5 eV increases as a square of the excitation intensity. The YL and GL bands are attributed to two charge states of the same defect, presumably a gallium vacancy-oxygen complex.

Backilluminated Gan/Algan Heterojunction Ultraviolet Photodetector With High Internal Gain, S. K. Zhang, W. B. Wang, I. Shtau, F. Yun, L. He, Hadis Morkoç, X. Zhou, M. Tamargo, R. R. Alfano

Electrical and Computer Engineering Publications

We report on a backilluminated GaN/Al0.18Ga0.82Nheterojunction ultraviolet (UV)photodetector with high internal gain based on metal-semiconductor-metal structures. A narrow band pass spectral response between 365 and 343 nm was achieved. When operating in dc mode, the responsivity reaches up to the order of 102 A/W under weak UVillumination, which is due to enormous internal gain up to 103. The linear dependence of photocurrent on bias and its square root dependence on optical power are found and explained by a trapping and recombination model. The high photocurrent gain is attributed to trapping and recombination centers with an acceptor character induced by dislocations …

Backilluminated Ultraviolet Photodetector Based On Gan/Algan Multiple Quantum Wells, S. K. Zhang, W. B. Wang, F. Yun, L. He, Hadis Morkoç, X. Zhou, M. Tamargo, R. R. Alfano

Electrical and Computer Engineering Publications

The operation of backilluminated ultraviolet (UV)photodetector based on GaN/Al0.27Ga0.73Nmultiple quantum wells(MQWs) is reported. The MQW structure was deposited on a 1-μm-thick Al0.35Ga0.65Nbuffer layer which was epitaxied on a sapphire substrate. Coplanar Ohmic contacts were made on the top side of the MQW structure. By illuminating the Ohmic contact positions from the backside of the detector, a flat and narrow band spectral response is achieved in the UV wavelength range from 297 nm to 352 nm. The electron-heavy hole absorption in the MQW region produces the sharp long-wavelength cutoff at 352 nm and the band-to-band absorption of the Al0.35Ga0.65Nbuffer layer introduces …

Growth Of Gan Films On Porous Sic Substrate By Molecular-Beam Epitaxy, F. Yun, Michael A. Reshchikov, L. He, Hadis Morkoç, C. K. Inoki, T. S. Kuan

Electrical and Computer Engineering Publications

Porous SiC (PSiC) substrates were used for the growth of GaN by reactive molecular-beam epitaxy with ammonia as the nitrogen source. Improved quality of GaNfilms has been demonstrated for growth on PSiC substrates, as compared to that on standard 6H–SiC substrates. Cross-sectional transmission electron microscopy and electron diffraction showed a reduction in dislocation density and a higher degree of lattice and thermal relaxation in the GaNfilmsgrown on porous substrates. The submicron GaNfilms exhibit a rocking curve linewidth of 3.3 arcmin for (0002) diffraction and 13.7 arcmin for (101̄2) diffraction. Low-temperature photoluminescence showed an excitonic transition with a full width at …

Defect Reduction With Quantum Dots In Gan Grown On Sapphire Substrates By Molecular Beam Epitaxy, D. Huang, Michael A. Reshchikov, F. Yun, T. King, A. A. Baski, Hadis Morkoç

Electrical and Computer Engineering Publications

The GaN films grown on buffer layers containing quantum dots by molecular beam epitaxy on sapphire substrates were investigated. The density of the dislocations in the films was determined by wet chemical etching and atomic force microscopy. It was found that the insertion of a set of multiple GaN quantum-dot layers in the buffer layer effectively reduces the density of the dislocations in the epitaxial layers. As compared to the dislocation density of ∼1010 cm−2in the typical GaN films grown on AlNbuffer layer, a density of ∼3×107 cm−2 was demonstrated in the GaN films grown with quantum dot layers.

Properties Of Alxga1−Xn Layers Grown By Plasma-Assisted Molecular-Beam Epitaxy Under Ga-Rich Conditions, L. He, Michael A. Reshchikov, F. Yun, D. Huang, T. King, Hadis Morkoç

Electrical and Computer Engineering Publications

AlxGa1−xN films were grown by plasma-assisted molecular-beam epitaxy on (0001)sapphire substrates under Ga-rich conditions. To control the AlxGa1−xN composition over the entire range, the Al and Ga arrival rates were fixed while the nitrogen arrival rate was varied. We have found that the Al fraction increased with decreasing N flow due to preferentially favorable bonding of Al and N over Ga and N. Consequently, the growth rate decreased as the Al mole fraction increased. A photoluminescence quantum efficiency at 15 K was markedly higher for the AlxGa1−xN layers grown under Ga-rich conditions (3%–48%) compared to the layers grown under N-rich …

Room-Temperature Single-Electron Charging In Electrochemically Synthesized Semiconductor Quantum Dot And Wire Array, N. Kouklin, L. Menon, Supriyo Bandyopadhyay

Electrical and Computer Engineering Publications

Cylindrical quantum dots of diameter ∼8 nm and height 3–10 nm, and wires of diameter 50 nm and height 500–1000 nm, were self-assembled by electrodepositing semiconductors in the nanometer-sized pores of anodic alumina films. Current–voltage characteristics of both wires and dots show Coulomb blockade at room temperature, while the wires also show a Coulomb staircase when exposed to infrared radiation. These results establish that electrochemicalself-assembly is a viable technique for producing nanostructures that have potential uses in room-temperature single electronics.

Energy Band Bowing Parameter In Alxga1-Xn Alloys, Feng Yun, Michael A. Reshchikov, Lei He, Thomas King, Hadis Morkoç, Steve W. Novak, Luncun Wei

Electrical and Computer Engineering Publications

Molecular-beam epitaxy grown AlxGa1−xN alloys covering the entire range of alloy compositions, 0⩽x⩽1, have been used to determine the alloy band gap dependence on its composition. The Alchemical composition was deduced from secondary ion mass spectroscopy and Rutherford backscattering. The composition was also inferred from x-ray diffraction. The band gap of the alloy was extracted from low temperature optical reflectance measurements which are relatively more accurate than photoluminescence. Fitting of the band gap data resulted in a bowing parameter of b=1.0 eV over the entire composition range. The improved accuracy of the composition and band gap determination …

Effective-Medium Theories For Predicting Hydrodynamic Transport Properties Of Bidisperse Suspensions, Ashok S. Sangani, Sangkyun Koo

Biomedical and Chemical Engineering - All Scholarship

Effective-medium theories for predicting conditionally averaged velocity field and hydrodynamic transport coefficients of monodisperse suspensions are extended to bidisperse suspensions. The predictions of the theory are shown to agree very well with the results of direct numerical simulations of bidisperse suspensions with hard-sphere configurations up to volume fractions at which phase separation in bidisperse hard-sphere systems are observed.

Closed Streamlines In Flow Visualization, Thomas Wischgoll

Computer Science and Engineering Faculty Publications

Vector Fields occur in many of the problems in science and engineering. In combustion processes for instance, vector fields describe the flow of the gas. This process can be enhanced using vector field visualization techniques. Also wind tunnel experiments can be analyzed. An example is the design of an air wing. The wing can be optimized to crate a smoother flow around it. Vector field visualization methods help the engineer to detect critical features of the flow. Consequently, feature detection methods gained great importance during the last years.

Topological methods are often used to visualize vector fields because they clearly …

Implementation Of A Si/Sic Hybrid Optically Controlled High-Power Switching Device, Prashant Bhadri, Kuntao Ye, Elena A. Guliants, Fred R. Beyette Jr.

Electrical and Computer Engineering Faculty Publications

The ever-increasing performance and economy of operation requirements placed on commercial and military transport aircraft are resulting in very complex systems. As a result, the use of fiber optic component technology has lead to high data throughput, immunity to EMI, reduced certification and maintenance costs and reduced weight features. In particular, in avionic systems, data integrity and high data rates are necessary for stable flight control. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Current fly-by-light systems are limited by …

Neil Armstrong, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

In addition to his outstanding and pioneering contributions to the National Aeronautics and Space Administration’s (NASA) crewed spaceflight program, Armstrong served with distinction as a professor of aerospace engineering, chairman and director of several corporations, and member of presidential commissions.

Design And Fabrication Of Polarization Filter Implementing A Wire Grid Array, Eric Poortinga

Journal of the Microelectronic Engineering Conference

For decades optical lithography has continually been extended past the conceived limitations of the technology. By optimizing photoresist performance and stepper settings it is possible to image features smaller then the wavelength of light being used to image. This ability allows structures to be designed such that the optical properties of the material change from what would occur at larger scales. One such structure is the wire grid array consisting of parallel metal lines on a quartz substrate. A wire grid array with a period smaller then the wavelength of incident radiation acts as a polarizer. The Incident field perpendicular …

Investigation Of Lens Aberrations Through Use Of Phase Shifting Structures At 365nm Technology, James Guerrero

Journal of the Microelectronic Engineering Conference

As CMOS technology pushes feature dimensions beyond the sub-wavelength threshold, the effect of lens aberrations in the imaging system becomes more relevant. Therefore, it becomes important that the optical engineer completely understands the effects lens aberrations have on aerial image and resist profile. It is also important to have a tool and a process that can accurately describe and measure the aberrations in the exposure system. With full characterization of the lens systems and through use of a lithographic simulator, it becomes possible to predict the imaging effects and ultimately critical dimensions and pattern placement. In any exposure system there …

Interferometric Lithography Optical System Utilizing A 442nm Hecd Laser, Frank C. Cropanese

Journal of the Microelectronic Engineering Conference

An interferometric optical lithography system utilizing a 442nm Helium Cadmium (HeCd) laser source has been developed. The HeCd laser was passed through a 2μm diffraction grating etched into a phase shift quartz mask to generate two mutually coherent light beams. The ±V’ diffraction orders were collected and interfered at angles ranging from o to 90° with respect to the substrate normal. Incident angles of 13, 26, 34, and 47° were implemented to produce corresponding pitches of 1.0, 0.5, 0.4 and 0.3μm, respectively. The smallest line width that was fabricated approached 0.10μm. In order to synthesize the behavior of conventional projection …