Engineering Commons^™

Quantification Of Thoracic Aorta Blood Flow By Magnetic Resonance Imaging During Supine Cycling Exercise Of Increasing Intensity, Laura M. Ellwein, John F. Ladisa, Stacy Leibham, Sheila M. Schindler-Ivens, Margaret M. Samyn

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Thin 3d Multiplication Regions In Plasmonically Enhanced Nanopillar Avalanche Detectors, Pradeep Senanayake, Chung-Hong Hung, Alan C. Farrell, David A. Ramirez, Joshua Shapiro, Chi-Kang Li, Yuh-Renn Wu, Majeed M. Hayat, Diana L. Huffaker

Electrical and Computer Engineering Faculty Research and Publications

We demonstrate a nanopillar (NP) device structure for implementing plasmonically enhanced avalanche photodetector arrays with thin avalanche volumes (∼ 310 nm × 150 nm × 150 nm). A localized 3D electric field due to a core–shell PN junction in a NP acts as a multiplication region, while efficient light absorption takes place via surface plasmon polariton Bloch wave (SPP-BW) modes due to a self-aligned metal nanohole lattice. Avalanche gains of ∼216 at 730 nm at −12 V are obtained. We show through capacitance–voltage characterization, temperature-dependent breakdown measurements, and detailed device modeling that the avalanche region is on the order of …

Altered Hemodynamics, Endothelial Function, And Protein Expression Occur With Aortic Coarctation And Persist After Repair, Arjun Menon, Thomas J. Eddinger, Hongfeng Wang, David C. Wendell, Jeffrey M. Toth, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Coarctation of the aorta (CoA) is associated with substantial morbidity despite treatment. Mechanically induced structural and functional vascular changes are implicated; however, their relationship with smooth muscle (SM) phenotypic expression is not fully understood. Using a clinically representative rabbit model of CoA and correction, we quantified mechanical alterations from a 20-mmHg blood pressure (BP) gradient in the thoracic aorta and related the expression of key SM contractile and focal adhesion proteins with remodeling, relaxation, and stiffness. Systolic and mean BP were elevated for CoA rabbits compared with controls leading to remodeling, stiffening, an altered force response, and endothelial dysfunction both …

Functional Classification Of Skeletal Muscle Networks. I. Normal Physiology, Yu Wang, John Winters, Shankar Subramaniam

Biomedical Engineering Faculty Research and Publications

Extensive measurements of the parts list of human skeletal muscle through transcriptomics and other phenotypic assays offer the opportunity to reconstruct detailed functional models. Through integration of vast amounts of data present in databases and extant knowledge of muscle function combined with robust analyses that include a clustering approach, we present both a protein parts list and network models for skeletal muscle function. The model comprises the four key functional family networks that coexist within a functional space; namely, excitation-activation family (forward pathways that transmit a motoneuronal command signal into the spatial volume of the cell and then use Ca …

The Effect Of Cone Opsin Mutations On Retinal Structure And The Integrity Of The Photoreceptor Mosaic, Joseph Carroll, Alfredo Dubra, Jessica C. Gardner, Liliana Mizrahi-Meissonnier, Robert F. Cooper, Adam M. Dubis, Rick Nordgren, Mohamed Genead, Thomas B. Connor Jr., Kimberly E. Stepien, Dror Sharon, David M. Hunt, Eyal Banin, Alison J. Hardcastle, Anthony T. Moore, David R. Williams, Gerald Fishman, Jay Neitz, Maureen Neitz, Michel Michaelides

Biomedical Engineering Faculty Research and Publications

Purpose.

To evaluate retinal structure and photoreceptor mosaic integrity in subjects with OPN1LW and OPN1MW mutations.

Methods.

Eleven subjects were recruited, eight of whom have been previously described. Cone and rod density was measured using images of the photoreceptor mosaic obtained from an adaptive optics scanning light ophthalmoscope (AOSLO). Total retinal thickness, inner retinal thickness, and outer nuclear layer plus Henle fiber layer (ONL+HFL) thickness were measured using cross-sectional spectral-domain optical coherence tomography (SD-OCT) images. Molecular genetic analyses were performed to characterize the OPN1LW/OPN1MW gene array.

Results.

While disruptions in retinal lamination and cone mosaic structure were observed …

Assessing Retinal Structure In Complete Congenital Stationary Night Blindness And Oguchi Disease, Pooja Godara, Robert F. Cooper, Panagiotis I. Sergouniotis, Melissa A. Diederichs, Megan R. Streb, Mohamed Genead, J. Jason Mcanany, Andrew R. Webster, Anthony T. Moore, Adam M. Dubis, Maureen Neitz, Alfredo Dubra, Edwin M. Stone, Gerald A. Fishman, Dennis P. Han, Michel Michaelides, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose

To examine retinal structure and changes in photoreceptor intensity after dark adaptation in patients with complete congenital stationary night blindness and Oguchi disease.

Design

Prospective, observational case series.

Methods

We recruited 3 patients with complete congenital stationary night blindness caused by mutations in GRM6, 2 brothers with Oguchi disease caused by mutations in GRK1, and 1 normal control. Retinal thickness was measured from optical coherence tomography images. Integrity of the rod and cone mosaic was assessed using adaptive optics scanning light ophthalmoscopy. We imaged 5 of the patients after a period of dark adaptation and examined layer …

Preliminary Investigation Of Residual Limb Plantarflexion And Dorsiflexion Muscle Activity During Treadmill Walking For Trans-Tibial Amputees, M. Barbara Silver-Thorn, Thomas Current, Benjamin Kuhse

Biomedical Engineering Faculty Research and Publications

Background: Novel powered prosthetic ankles currently incorporate finite state control, using kinematic and kinetic sensors to differentiate stance and swing phases/sub-phases and control joint impedance and position or torque. For more intuitive control, myoelectric control of the ankle using the remnant residual limb dorsiflexors and plantarflexors, perhaps in concert with kinetic and kinematic sensors, may be possible.

Objective: The specific research objective was to assess the feasibility of using myoelectric control of future active or powered prosthetic ankle joints for trans-tibial amputees.

Study Design: The project involved human subject trials to determine whether current techniques of myoelectric control of upper …

Diffusion Tensor Imaging And Tractography In Brown-Sequard Syndrome, A. Vendatam, Michael B. Jirjis, Brian D. Schmit, M. D. Budde, J. L. Ulmer, Mei Wang, S. N. Kurpad

Biomedical Engineering Faculty Research and Publications

This report illustrates the utility of DTI and DTT in delineating regions of cord injury in two patients with traumatic Brown-Sequard syndrome. Our results indicate that DTI provides clinically relevant information that supplements conventional MR imaging for patients with acute SCI.

Differential Lung Uptake Of 99mtc-Hexamethylpropyleneamine Oxime And 99mtc-Duramycin In The Chronic Hyperoxia Rat Model, Anne V. Clough, Said H. Audi, Steven Thomas Haworth, David L. Roerig

Biomedical Engineering Faculty Research and Publications

Noninvasive radionuclide imaging has the potential to identify and assess mechanisms involved in particular stages of lung injury that occur with acute respiratory distress syndrome, for example. Lung uptake of ^99mTc-hexamethylpropyleneamine oxime (HMPAO) is reported to be partially dependent on the redox status of the lung tissue whereas ^99mTc-duramycin, a new marker of cell injury, senses cell death via apoptosis or necrosis. Thus, we investigated changes in lung uptake of these agents in rats exposed to hyperoxia for prolonged periods, a common model of acute lung injury. Methods: Male Sprague–Dawley rats were preexposed to either normoxia (21% O …

Stress Monitoring Of Post-Processed Mems Silicon Microbridge Structures Using Raman Spectroscopy, Lavern A. Starman, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated Micro-Electro-Mechanical Systems (MEMS) devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not well controlled during deposition. The residual stress; for example, tends to vary significantly for different deposition methods. Currently, few nondestructive techniques are available to measure residual stress in MEMS devices prior to the final release etch. In this research, micro-Raman spectroscopy is used to measure the residual stresses in polysilicon MEMS microbridge devices. This …

First-Order Design Of A Reflective Viewfinder For Adaptive Optics Ophthalmoscopy, Alfredo Dubra, Yusufu N. Sulai

Biomedical Engineering Faculty Research and Publications

Adaptive optics (AO) ophthalmoscopes with small fields of view have limited clinical utility. We propose to address this problem in reflective instruments by incorporating a viewfinder pupil relay designed by considering pupil and image centering and conjugation. Diverting light from an existing pupil optical relay to the viewfinder relay allows switching field of view size. Design methods that meet all four centering and conjugation conditions using either a single concave mirror or with two concave mirrors forming an off-axis afocal telescope are presented. Two different methods for calculating the focal length and orientation of the concave mirrors in the afocal …

Tyrosine Nitration Of Voltage-Dependent Anion Channels In Cardiac Ischemia-Reperfusion: Reduction By Peroxynitrite Scavenging, Meiying Yang, Amadou K.S. Camara, Bassam T. Wakim, Yifan Zhou, Ashish K. Gadicherla, Wai-Meng Kwok, David F. Stowe

Biomedical Engineering Faculty Research and Publications

Excess superoxide (O₂⁻) and nitric oxide (NO) forms peroxynitrite (ONOO⁻) during cardiac ischemia reperfusion (IR) injury, which in turn induces protein tyrosine nitration (tyr-N). Mitochondria are both a source of and target for ONOO⁻. Our aim was to identify specific mitochondrial proteins that display enhanced tyr-N after cardiac IR injury, and to explore whether inhibiting O₂⁻/ONOO⁻ during IR decreases mitochondrial protein tyr-N and consequently improves cardiac function. We show here that IR increased tyr-N of 35 and 15 kDa mitochondrial proteins using Western blot analysis with 3-nitrotyrosine antibody. Immunoprecipitation …

Mitigation Of Radiation Induced Pulmonary Vascular Injury By Delayed Treatment With Captopril, Robert C. Molthen, Qingping Wu, Brian L. Fish, John E. Moulder, Elizabeth R. Jacobs, Meetha M. Medhora

Biomedical Engineering Faculty Research and Publications

Background and Objective: A single dose of 10 Gy radiation to the thorax of rats results in decreased total lung angiotensin-converting enzyme (ACE) activity, pulmonary artery distensibility and distal vascular density while increasing pulmonary vascular resistance (PVR) at 2 months post-exposure. In this study, we evaluate the potential of a renin-angiotensin system (RAS) modulator, the ACE inhibitor captopril, to mitigate this pulmonary vascular damage.

Methods: Rats exposed to 10 Gy thorax only irradiation and age-matched controls were studied 2 months after exposure, during the development of radiation pneumonitis. Rats were treated, either immediately or 2 weeks after radiation exposure, with …

Functional Classification Of Skeletal Muscle Networks. Ii. Applications To Pathophysiology, Yu Wang, Jack Winters, Shankar Subramaniam

Biomedical Engineering Faculty Research and Publications

In our preceding companion paper (Wang Y, Winters J, Subramaniam S. J Appl Physiol. doi: 10.1152/japplphysiol.01514.2011), we used extensive expression profile data on normal human subjects, in combination with legacy knowledge to classify skeletal muscle function into four models, namely excitation-activation, mechanical, metabolic, and signaling-production model families. In this paper, we demonstrate how this classification can be applied to study two well-characterized myopathies: amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD). Using skeletal muscle profile data from ALS and DMD patients compared with that from normal subjects, normal young in the case of DMD, we delineate molecular mechanisms …

Impairments In Sensorimotor Control During Pursuit And Compensatory Tracking In Individuals With Multiple Sclerosis, Scott A. Beardsley, Heenan M., Robert A. Scheidt, D. Woo, J. Bobholz

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Monosynaptic Functional Connectivity In Cerebral Cortex During Wakefulness And Under Graded Levels Of Anesthesia, Jeannette A. Vizuete, Siveshigan Pillay, Kamran Diba, Kristina M. Ropella, Anthony G. Hudetz

Biomedical Engineering Faculty Research and Publications

The balance between excitation and inhibition is considered to be of significant importance for neural computation and cognitive function. Excitatory and inhibitory functional connectivity in intact cortical neuronal networks in wakefulness and graded levels of anesthesia has not been systematically investigated. We compared monosynaptic excitatory and inhibitory spike transmission probabilities using pairwise cross-correlogram (CCG) analysis. Spikes were measured at 64 sites in the visual cortex of rats with chronically implanted microelectrode arrays during wakefulness and three levels of anesthesia produced by desflurane. Anesthesia decreased the number of active units, the number of functional connections, and the strength of excitatory connections. …

Fabrication Process Comparison And Dynamics Evaluation Of Electrothermal Actuators For A Prototype Mems Safe And Arming Devices, Scott A. Ostrow Ii, Robert A. Lake, J. P. Lombardi Iii, Ronald A. Coutu Jr., Lavern A. Starman

Electrical and Computer Engineering Faculty Research and Publications

Electrothermal actuators fabricated using the Polysilicon Multi-User MEMS Process (PolyMUMPs) and the Sandia Ultra-Planar, Multi-Level MEMS Technology 5 (SUMMiT V) have been investigated for use in integrated microelectromechanical systems (MEMS) safe and arming devices. The fabricated electrothermal actuators have been dynamically tested to determine and compare the responses of devices from both processes. Furthermore, the integration of these devices into a safe and arming device were tested and investigated for each process. Initial results indicate that the SUMMiT devices provide the most optimum results based on consistency of operation and reliability.

Sar-Based Vibration Estimation Using The Discrete Fractional Fourier Transform, Qi Wang, Matthew Pepin, Ryan J. Beach, Ralf Dunkel, Tom Atwood, Balu Santhanam, Walter Gerstle, Armin W. Doerry, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

A vibration estimation method for synthetic aperture radar (SAR) is presented based on a novel application of the discrete fractional Fourier transform (DFRFT). Small vibrations of ground targets introduce phase modulation in the SAR returned signals. With standard preprocessing of the returned signals, followed by the application of the DFRFT, the time-varying accelerations, frequencies, and displacements associated with vibrating objects can be extracted by successively estimating the quasi-instantaneous chirp rate in the phase-modulated signal in each subaperture. The performance of the proposed method is investigated quantitatively, and the measurable vibration frequencies and displacements are determined. Simulation results show that the …

Design And Validation Of Bending Test Method For Characterization Of Miniature Pediatric Cortical Bone Specimens, Carolyne Albert, John Jameson, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Osteogenesis imperfecta is a genetic disorder of bone fragility; however, the effects of this disorder on bone material properties are not well understood. No study has yet measured bone material strength in humans with osteogenesis imperfecta. Small bone specimens are often extracted during routine fracture surgeries in children with osteogenesis imperfecta. These specimens could provide valuable insight into the effects of osteogenesis imperfecta on bone material strength; however, their small size poses a challenge to their mechanical characterization. In this study, a validated miniature three-point bending test is described that enables measurement of the flexural material properties of pediatric cortical …

Enhancing The Engineering Curriculum: Defining Discovery Learning At Marquette University, Jay R. Goldberg, Mark L. Nagurka

Biomedical Engineering Faculty Research and Publications

This paper summarizes the results of our investigation into the feasibility of increasing the level of discovery learning in the College of Engineering (COE) at Marquette University. We review the education literature, document examples of discovery learning currently practiced in the COE and other schools, and propose a Marquette COE-specific definition of discovery learn-ing. Based on our assessment of the benefits, costs, and tradeoffs associated with increasing the level of discovery learning, we pre-sent several recommendations and identify resources required for implementation. These recommendations may be helpful in enhancing engineering education at other schools.

Noise Impacts From Professional Dog Grooming Forced-Air Dryers, Peter M. Scheifele, Michael T. Johnson, David C. Byrne, John G. Clark, Ashley Vandlik, Laura W. Kretschmer, Kristine E. Sonstrom

Electrical and Computer Engineering Faculty Research and Publications

This study was designed to measure the sound output of four commonly used brands of forced-air dryers used by dog groomers in the United States. Many dog groomers have questions about the effect of this exposure on their hearing, as well as on the hearing of the dogs that are being groomed. Readings taken from each dryer at 1 meter (the likely distance of the dryer from the groomer and the dog) showed average levels ranging from 105.5 to 108.3 dB SPL or 94.8 to 108.0 dBA. Using the 90 dBA criterion required by the US Occupational Safety and Health …

Bayesian Speaker Adaptation Based On A New Hierarchical Probabilistic Model, Wen-Lin Zhang, Wei-Qiang Zhang, Bi-Cheng Li, Dan Qu, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

In this paper, a new hierarchical Bayesian speaker adaptation method called HMAP is proposed that combines the advantages of three conventional algorithms, maximum a posteriori (MAP), maximum-likelihood linear regression (MLLR), and eigenvoice, resulting in excellent performance across a wide range of adaptation conditions. The new method efficiently utilizes intra-speaker and inter-speaker correlation information through modeling phone and speaker subspaces in a consistent hierarchical Bayesian way. The phone variations for a specific speaker are assumed to be located in a low-dimensional subspace. The phone coordinate, which is shared among different speakers, implicitly contains the intra-speaker correlation information. For a specific speaker, …

Creep Evaluation Of (Orthotic) Cast Materials During Simulated Clubfoot Correction, T. L. Cohen, H. Altiok, Sergey Tarima, P. A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

The Ponseti method is a widely accepted and highly successful conservative treatment of pediatric clubfoot that relies on weekly manipulations and cast applications. However, the material behavior of the cast in the Ponseti technique has not been investigated. The current study sought to characterize the ability of two standard casting materials to maintain the Ponseti corrected foot position by evaluating creep response. A dynamic cast testing device (DCTD) was built to simulate a typical pediatric clubfoot. Semi-rigid fiberglass and rigid fiberglass casting materials were applied to the device, and the rotational creep was measured at various constant torques. The movement …

Chronically Inadequate Sleep Results In Abnormal Bone Formation And Abnormal Bone Marrow In Rats, Carol A. Everson, Anne E. Folley, Jeffrey M. Toth

Biomedical Engineering Faculty Research and Publications

Insufficient sleep over long durations of the lifespan is believed to adversely affect proper development and healthful aging, although how this might become manifested is unknown. In the present study, rats were repeatedly sleep-restricted during 72 days to permit maladaptations to evolve, thereby permitting study. Densitometric and histomorphometric analyses were performed on harvested bone. In sleep-restricted rats, bone lined by osteoid was reduced 45-fold and osteoid thickness was decreased, compared with controls. This corresponded to a decrease in osteoblast number and activity. The percentage of bone lined by osteoclasts did not differ from that of controls. Plasma concentrations of an …

Mechanism State Matrices For Spatial Reconfigurable Mechanisms, Philip A. Voglewede, Brian Korves, Brian Slaboch

Mechanical Engineering Faculty Research and Publications

This paper improves augmented mechanism state matrices by replacing joint code with screw system notation. The proposed substitution allows for a more specific description of the joints in the mechanism and the capability to describe both spatial and planar mechanisms. Examples are provided which elucidate the proposed approach.

Configuration Space Analysis And Synthesis Of Planar Variable Kinematic Joints, Brian Slaboch, Philip A. Voglewede

Mechanical Engineering Faculty Research and Publications

No abstract provided.

A Dynamic Model Of A Belt Driven Electromechanical Xy Plotter Cutter, Joseph Prisco, Philip A. Voglewede

Mechanical Engineering Faculty Research and Publications

No abstract provided.

Controller Design And Preliminary Testing Of A Powered Below-Knee Prosthetic Device, Philip A. Voglewede, Jinming Sun

Mechanical Engineering Faculty Research and Publications

No abstract provided.

Ambient Habitat Noise And Vibration At The Georgia Aquarium, Peter M. Scheifele, Michael T. Johnson, Laura W. Kretschmer, John G. Clark, D. Kemper, G. Potty

Electrical and Computer Engineering Faculty Research and Publications

Underwater and in-air noise evaluations were completed in performance pool systems at Georgia Aquarium under normal operating conditions and with performance sound tracks playing. Ambient sound pressure levels at in-pool locations, with corresponding vibration measures from life support system (LSS) pumps, were measured in operating configurations, from shut down to full operation. Results indicate noise levels in the low frequency ranges below 100 Hz were the highest produced by the LSS relative to species hearing thresholds. The LSS had an acoustic impact of about 10 dB at frequencies up to 700 Hz, with a 20 dB re 1 μPa impact …

Upper Extremity Biomechanical Model For Evaluation Of Pediatric Joint Demands During Wheelchair Mobility, Alyssa J. Paul, Brooke A. Slavens, Adam Graf, Joseph Krzak, Lawrence Vogel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Current methods for evaluating upper extremity (UE) dynamics during pediatric wheelchair use are limited. We propose a new model to characterize UE joint kinematics and kinetics during pediatric wheelchair mobility. The bilateral model is comprised of the thorax, clavicle, scapula, upper arm, forearm, and hand segments. The modeled joints include: sternoclavicular, acromioclavicular, glenohumeral, elbow and wrist. The model is complete and is currently undergoing pilot studies for clinical application. Results may provide considerable quantitative insight into pediatric UE joint dynamics to improve wheelchair prescription, training and long term care of children with orthopaedic disabilities.