Digital Commons Network^™

Modeling Nerve Electro-Stimulation In The Nanosecond Regime, Feng Chen

Electrical & Computer Engineering Theses & Dissertations

Numerical simulations of electrical stimulation of frog gastrocnemius muscles have been carried out for pulse durations in the nanosecond regime. There are a number of potential advantages in using ultra-short pulses for neural stimulation, and no previous electro-stimulation work in the sub-microsecond regime has been reported. A timedependent, three-dimensional analysis model was developed and implemented for three distinct situations: (i) direct stimulation via electrode contact, (ii) indirect excitation based on electrodes immersed in a saline-filled bath, and (iii) remote electromagnetic stimulation through vacuum. The simulations yielded strength-dm ation (S-D) curves with pulse durations as short as 5 ns. Good agreement …

A Theoretical Analysis Of Long-Term Bisphosphonate Effects On Trabecular Bone Volume And Microdamage, Jeffry S. Nyman, Oscar C. Yeh, Scott J. Hazelwood, R. Bruce Martin

Biomedical Engineering

Bisphosphonates increase bone mass and reduce fracture risk, but their anti-resorptive action may lead to increases in fatigue microdamage. To investigate how bisphosphonate effects influence changes in bone volume and microdamage in the long term, a strain-adaptive model of bone remodeling and microdamage balance was developed for a continuum-level volume of postmenopausal trabecular bone by invoking Frost's mechanostat hypothesis. Both disuse and fatigue microdamage were assumed to stimulate the activation frequency of basic multicellular units (BMUs) such that bone remodeling served to remove excess bone mass and microdamage. Bisphosphonate effects were simulated as follows: low, intermediate, high, or complete suppression …

Notes On Equilibria In Symmetric Games, Shih-Fen Cheng, Daniel M. Reeves, Yevgeniy Vorobeychik, Michael P. Wellman

Research Collection School Of Computing and Information Systems

In a symmetric game, every player is identical with respect to the game rules. We show that a symmetric 2strategy game must have a pure-strategy Nash equilibrium. We also discuss Nash’s original paper and its generalized notion of symmetry in games. As a special case of Nash’s theorem, any finite symmetric game has a symmetric Nash equilibrium. Furthermore, symmetric infinite games with compact, convex strategy spaces and continuous, quasiconcave utility functions have symmetric pure-strategy Nash equilibria. Finally, we discuss how to exploit symmetry for more efficient methods of finding Nash equilibria.

Spectroscopic And Microscopic Investigation Of The Corrosion Of 316/316l Stainless Steel By Lead-Bismuth Eutectic (Lbe) At Elevated Temperatures: Importance Of Surface Preparation, Allen L. Johnson, Denise Parsons, Julia Manzerova, Dale L. Perry, Daniel Koury, Brian D. Hosterman, John Farley

Transmutation Sciences Materials (TRP)

The corrosion of steel by lead–bismuth eutectic (LBE) is an important issue in proposed nuclear transmutation schemes. Russian scientists at the IPPE exposed steel samples to oxygen-controlled LBE at temperatures up to 823 K and exposure times up to 3000 h. We have characterized these post-exposure steel samples and unexposed controls, using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX) and X-ray photoelectron spectroscopy (XPS). Previous researchers have investigated the corrosion by LBE of steel of varying composition. In the present work, we compared two samples having the same composition (standard nuclear grade 316/316L) but different surface preparation: a cold-rolled …

Inside Unlv, Holly Ivy De Vore, Carol C. Harter, Stuart Mann

Inside UNLV

No abstract provided.

Energy-Landscape-Model Analysis For Irreversibility And Its Pulse-Width Dependence In Cells Subjected To A High-Intensity Ultrashort Electric Pulse, R. P. Joshi, Q. Hu, Karl H. Schoenbach, Stephen J. Beebe

Bioelectrics Publications

We provide a simple, but physical analysis for cell irreversibility and apoptosis in response to an ultrashort (nanosecond), high-intensity electric pulse. Our approach is based on an energy landscape model for determining the temporal evolution of the configurational probability function p(q). The primary focus is on obtaining qualitative predictions of a pulse width dependence to apoptotic cell irreversibility that has been observed experimentally. The analysis couples a distributed electrical model for current flow with the Smoluchowski equation to provide self-consistent, time-dependent transmembrane voltages. The model captures the essence of the experimentally observed pulse-width dependence, and provides a possible physical picture …

Real-Time Measurements On The Effects Of Ultra-Short High Voltage Pulses On Hl-60 Cells, Michalis C. Artemiou

Electrical & Computer Engineering Theses & Dissertations

The application of high voltage microsecond pulses that are above a critical value, to biological cells, has been shown to cause electroporation (Neumann, 1989). In addition, ultra-short pulses of several tens to hundreds of nanoseconds duration have been recently shown to affect intracellular structures without disturbing the plasma membrane (Schoenbach, 2001). However, such ultra-short intense pulses are expected to cause deformation of cells due to Maxwell stresses. This deformation was studied by means of an imaging technique with 10 ns temporal resolution on HL-60 cells. The imaging system consists of an inverted microscope where a spark light source was used …

Impact Of Pulmonary Arterial Endothelial Cells On Duroquinone Redox Status, Marilyn P. Merker, Robert D. Bongard, Gary S. Krenz, Hongtao Zhao, Viola S. Fernandes, Balaraman Kalyanaraman, Neil Hogg, Said H. Audi

Biomedical Engineering Faculty Research and Publications

The study objective was to use pulmonary arterial endothelial cells to examine kinetics and mechanisms contributing to the disposition of the quinone 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ) observed during passage through the pulmonary circulation. The approach was to add DQ, durohydroquinone (DQH₂), or DQ with the cell membrane-impermeant oxidizing agent, ferricyanide (Fe(CN)₆³⁻), to the cell medium, and to measure the medium concentrations of substrates and products over time. Studies were carried out under control conditions and with dicumarol, to inhibit NAD(P)H:quinone oxidoreductase 1 (NQO1), or cyanide, to inhibit mitochondrial electron transport. In control cells, DQH₂ appears …

Automatic Detection And Validity Of The Sea-Ice Edge: An Application Of Enhanced-Resolution Quikscat/Seawinds Data, David G. Long, Jorg Haarpaintner, Rasmus T. Tonboe, Michael L. Van Woert

Faculty Publications

Sea-ice edge detection is an essential task at the different national ice services to secure navigation in ice-covered seas. Comparison between the Remund and Long ice mask image from enhanced-resolution QuikScat/SeaWinds (QS) products and the analyzed ice edge from high-resolution RADARSAT synthetic aperture radar has shown that the automatically determined QS ice mask underestimates the Arctic ice extent. QS data was statistically analyzed by colocating the data with ice charts around Greenland and with the National Aeronautics and Space Administration Team's Special Sensor Microwave/Imager (SSM/I) ice concentration algorithm over the whole Arctic region. All variables, i.e., the backscatter in vertical …

Dynamical Studies Of Model Membrane And Cellular Response To Nanosecond, High-Intensity Pulsed Electric Fields, Qin Hu

Electrical & Computer Engineering Theses & Dissertations

The dynamics of electroporation of biological cells subjected to nanosecond, high intensity pulses are studied based on a coupled scheme involving the current continuity and Smoluchowski equations. The improved pore formation energy model includes a dependence on pore population and density. It also allows for variable surface tension and incorporates the effects of finite conductivity on the electrostatic correction term, which was not considered by the simple energy models in the literature. It is shown that E(r) becomes self-adjusting with variations in its magnitude and profile. The whole scheme is self-consistent and dynamic.

An electromechanical analysis based on thin-shell theory …

Brain Motion And Deformation During Closed Head Injury In The Presence Of Cerebrospinal Fluid, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This paper presents a new analysis of the physics of closed head injury following brief, intense acceleration of the head. It focuses upon the buoyancy of the brain in cerebrospinal fluid, which protects against damage, the propagation of strain waves through the brain substance, which causes damage, and the concentration of strain in critical anatomic regions, which magnifies damage. Numerical methods are used to create animations or "movies" of brain motion and deformation. Initially a 1 cm gap filled with cerebrospinal fluid (CSF) separates the brain from the skull. Whole head acceleration induces artificial gravity within the skull. The brain …

Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

After considering the heating mechanisms, casting issues, crucible design and issues related to the mass transport of americium, an ISM system was selected for melting the feedstock and casting fuel pins containing high vapor pressure actinides (americium). The finite element commercial software (FIDAP) was used to simulate the induction melting process and the casting process. Phase change is considered both in the heating and in the solidification process. Various factors and properties are studied, such as boundary conditions and initial conditions, output current, frequency of the current, main dimensions of the system, mold preheating temperature, heat transfer coefficient and mold …

Emissions Pathways, Climate Change, And Impacts On California, Katherine Hayhoe, Daniel Cayan, Christopher B. Field, Peter C. Frumhoff, Edwin P. Maurer, Norman L. Miller, Susanne C. Moser, Stephen H. Schneider, Kimberly Nicholas Cahill, Elsa E. Cleland, Larry Dale, Ray Drapek, R. Hanemann, Laurence S. Kalkstein, James Lenihan, Claire K. Lunch, Ronald P. Nielson, Scott C. Sheridan, Julia H. Verville

Civil, Environmental and Sustainable Engineering

The magnitude of future climate change depends substantially on the greenhouse gas emission pathways we choose. Here we explore the implications of the highest and lowest Intergovernmental Panel on Climate Change emissions pathways for climate change and associated impacts in California. Based on climate projections from two state-of-the-art climate models with low and medium sensitivity (Parallel Climate Model and Hadley Centre Climate Model, version 3, respectively), we find that annual temperature increases nearly double from the lower B1 to the higher A1fi emissions scenario before 2100. Three of four simulations also show greater increases in summer temperatures as compared with …

Description And Assessment Of A Business Plan Competition And New Venture Fair At San José State University, Malu Roldan, Asbjorn Osland, Michael Solt, Burton Dean

Faculty Publications

After the first business plan competition, in May 2003, San José State University (SJSU) faculty and community entrepreneurs serving on the university’s Silicon Valley Center for Entrepreneurship (SVCE) concluded that the process should be spread over an academic year. Hence, the New Venture Fair (NVF) was born, which was held Dec. 16, 2003. The feedback from all sources has been very positive regarding the NVF. A significant NVF exhibit was the Hewlett Packard Mobile Computing Grant (HPMCG). All teams completed projects that were impressive to most observers from the university and greater community but additional lessons were learned that will …

Interactive Demonstrations And Laboratories Using Shape Memory Alloys, Wendy C. Crone, Eric J. Voss, Katherine C. Chen

Materials Engineering

Shape memory alloys (SMAs) constitute a unique class of materials that undergo a reversible phase transformation allowing the material to display dramatic stress-induced and temperature-induced deformations that are recoverable. Nickel titanium (NiTi) is a shape memory alloy used in a wide variety of biomedical, aerospace, automotive and other applications. The austenite-martensite phase transformation that occurs in these alloys with changes in temperature or applied stress is responsible for the unique properties of this material. The unusual behavior of SMAs provides an exciting way to engage students and can be incorporated into a variety of courses under topics such as phase …

Development Of A Multidisciplinary Engineering Foundation Spiral, Samuel Bogan Daniels, Bouzid Aliane, Jean Nocito-Gobel, Michael Collura

Engineering and Applied Science Education Faculty Publications

To operate effectively in today’s workforce engineers need to have a muti-disciplinary perspective along with substantial disciplinary depth. This broad perspective cannot be achieved by merely taking 2 or 3 engineering courses outside of the major, but rather will require a radical change in the way we educate engineers. The faculty of the School of Engineering and Applied Science at the University of New Haven have developed a new approach: the Multidisciplinary Engineering Foundation Spiral. This curricular model provides the needed mix of breadth and depth, along with the desired professional skills, by providing carefully crafted, well-coordinated curricular experiences in …

A Case Study Of S-Curve Regression Method To Project Control Of Construction Management Via T-S Fuzzy Model, Ting-Ya Hsieh, Morris Hsiao-Lung Wang, Cheng-Wu Chen

Journal of Marine Science and Technology–Taiwan

In the contractual business, construction firms are generally more concerned with short-term financial strategies than the longterm ones. Working capital management is the central issue of all short-term financial concerns. Thus, it's urgent to study the cash portion of working capital management to rationalize the amount of cash and current assets possessed in certain time. The S-curve is quite suitable to represent the relationship between project duration and complete progress in practical usage of construction management. Based on the technique of Takagi-Sugeno (T−S) fuzzy model, the fuzzy regression model is constructed for curve fitting problems. According to the cash flow …

Optimization Of Cell Density And Dilution Rate In Pichia Pastoris Continuous Fermentations For Production Of Recombinant Proteins, Wenhui Zhang, Chih-Ping Liu, Mehmet Inan, Michael M. Meagher

Papers in Biomolecular Engineering

This paper provides an approach for optimizing the cell density (X_c) and dilution rate (D) in a chemostat for a Pichia pastoris continuous fermentation for the extracellular production of a recombinant protein, interferon τ (INF-τ). The objective was to maximize the volumetric productivity (Q, mg INF-τ I^-1 h^-1), which was accomplished using response surface methodology (RSM) to model the response of Q as a function of X_c and D within the ranges 150 ≤ X_c ≤ 450 g cells (wet weight) l^-1 and 0.1 μm ≤ D …

On-The-Go Soil Sensors For Precision Agriculture, Viacheslav I. Adamchuk, J. W. Hummel, M. T. Morgan, S. K. Upadhyaya

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The basic objectives of site-specific management of agricultural inputs are to increase profitability of crop production, improve product quality, and protect the environment. Information about the variability of different soil attributes within a field is essential for the decision-making process. The inability to obtain soil characteristics rapidly and inexpensively remains one of the biggest limitations of precision agriculture. Numerous researchers and manufacturers have attempted to develop on-the-go soil sensors to measure mechanical, physical and chemical soil properties. The sensors have been based on electrical and electromagnetic, optical and radiometric, mechanical, acoustic, pneumatic, and electrochemical measurement concepts. While only electric and …

Optimization Of A Quantum Cascade Laser Operating In The Terahertz Frequency Range Using A Multiobjective Evolutionary Algorithm, Traci A. Keller

Theses and Dissertations

A quantum cascade (QC) laser is a specific type of semiconductor laser that operates through principles of quantum mechanics. In less than a decade QC lasers are already able to outperform previously designed double heterostructure semiconductor lasers. Because there is a genuine lack of compact and coherent devices which can operate in the far-infrared region the motivation exists for designing a terahertz QC laser. A device operating at this frequency is expected to be more efficient and cost effective than currently existing devices. It has potential applications in the fields of spectroscopy, astronomy, medicine and free-space communication as well as …

Morpheus: Motif Oriented Representations To Purge Hostile Events From Unlabeled Sequences, Guarav Tandon, Debasis Mitra, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Most of the prevalent anomaly detection systems use some training data to build models. These models are then utilized to capture any deviations resulting from possible intrusions. The efficacy of such systems is highly dependent upon a training data set free of attacks. "Clean" or labeled training data is hard to obtain. This paper addresses the very practical issue of refinement of unlabeled data to obtain a clean data set which can then train an online anomaly detection system. Our system, called MORPHEUS, represents a system call sequence using the spatial positions of motifs (subsequences) within the sequence. We also …

Aaas Lecture Series On Women In Science And Engineering, Maribel Vazquez

Publications and Research

The winning essay for a Travel Award from the American Association for the Advancement in Science Women Lecture Series.

http://ehrweb.aaas.org/womeninscience/essays/vazquez.htm

Prediction Of Growth Factor Effects On Engineered Cartilage Composition Using Deterministic And Stochastic Modeling, Sean S. Kohles, Asit K. Saha, J. (Jagannath) Mazumdar

Mechanical and Materials Engineering Faculty Publications and Presentations

In the design of engineered tissues, guided balance of biomaterial degeneration with tissue synthesis offers refined control of construct development. The objective of this study was to develop a mathematical model that describes the steady state metabolism of extracellular matrix molecules (ECM: glycosaminoglycan and collagen) in an engineered cartilage construct taking into account localized environmental changes that may arise because of the application of growth factors. The variable effects of growth factors were incorporated in the form of random noise rather than the difference in rates of synthesis and catabolism. Thus, the frequency of ECM accumulation for each matrix molecule …

Interferometric And Holographic Imaging Of Surface-Breaking Cracks, James Lawrence Blackshire, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

Two advanced nondestructive evaluation systems are developed for imaging surface-breaking cracks in aerospace materials. The systems use scanning heterodyne interferometry and frequency-translated holography principles to image ultrasonic displacement fields on material surfaces with high resolution and sensitivity. Surface-breaking cracks are detected and characterized by visualizing near-field ultrasonic scattering processes, which in turn results in local intensification of ultrasonic displacement fields in the immediate vicinity of a crack. The local intensification permits cracks to be easily distinguished from background levels, and creates unique displacement field images that follow the contours and morphology of the cracks with microscopic precision. The interferometric and …

Ascertaining The Importance Of Neurons To Develop Better Brain-Machine Interfaces, Justin C. Sanchez, Jose M. Carmena, Mikhail A. Lebedev, Miguel A.L. Nicolelis, John G. Harris, Jose C. Principe

Electrical and Computer Engineering Faculty Research & Creative Works

In the design of brain-machine interface (BMI) algorithms, the activity of hundreds of chronically recorded neurons is used to reconstruct a variety of kinematic variables. A significant problem introduced with the use of neural ensemble inputs for model building is the explosion in the number of free parameters. Large models not only affect model generalization but also put a computational burden on computing an optimal solution especially when the goal is to implement the BMI in low-power, portable hardware. In this paper, three methods are presented to quantitatively rate the importance of neurons in neural to motor mapping, using single …

Inside Unlv, Holly Ivy De Vore, Caryn Key, Carol C. Harter, Richard Morgan

Inside UNLV

No abstract provided.

Optimization Studies Of Thermal Bimorph Cantilevers, Electrostatic Torsion Actuators And Variable Capacitors, Wuyong Peng

Dissertations

In this dissertation, theoretical analyses and optimization studies are given for three kinds of MEMS devices: thermal bimorph cantilevers, electrostatic torsion actuators, and variable capacitors. Calculation, simulation, and experimental data are used to confirm the device behavior and demonstrate the application of the design approaches.

For thermal bimorph cantilevers, an analytical model is presented which allows theoretical analysis and quantitative optimization of the performance based on material properties and device dimensions. Bimorph cantilevers are divided into two categories for deflection optimization: either the total thickness is constant, or the cantilever has one constant and one variable layer thickness. The optimum …

Mobile Agent Based Distributed Network Management : Modeling, Methodologies And Applications, Jian Ye

Dissertations

The explosive growth of the Internet and the continued dramatic increase for all wireless services are fueling the demand for increased capacity, data rates, support of multimedia services, and support for different Quality of Services (QoS) requirements for different classes of services. Furthermore future communication networks will be strongly characterized by heterogeneity. In order to meet the objectives of instant adaptability to the users' requirements and of interoperability and seamless operation within the heterogeneous networking environments, flexibility in terms of network and resource management will be a key design issue. The new emerging technology of mobile agent (MA) has arisen …

Novel Internally-Staged Ultrafiltration For Protein Purification, Meredith Ann Feins

Dissertations

A new ultrafiltration technique based on a multimembrane stack has been developed to fractionate proteins closer in molecular weight than conventionally possible. The technique is illustrated here by obtaining a pure protein product from a binary protein mixture. By employing membranes in series using the same membrane without any gaskets or spacers in-between, ultrafiltration is carried out to separate two proteins relatively close in molecular weight. Flat membranes, of the same molecular weight cutoff (MWCO) 30,000 or 100,000, are stacked together in the desired number, and ultrafiltration takes place. The membrane rejection of a protein is amplified with each additional …

Fabrication Of Nanofiber Scaffolds By Electrospinning And It's Potential For Tissue Engineering, Shobana Shanmugasundaram

Theses

Electrospinning is a fabrication process that uses an electric field to control the deposition of polymer fibers on to a target substrate. This electrospinning strategy can be used to fabricate fibrous polymer mats composed of fiber diameters ranging from several microns down to tens of nanometers. This study assesses the potential of electrospinning, as an alternative scaffold fabrication technique for tissue engineering applications. In this study, electrospinning is adapted to produce tissue-engineering scaffolds of two different size ranges composed of non-woven poly-L-lactide (PLLA) nanofibers and as a first study, the potential use of these scaffolds as tissue engineering scaffolds was …