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Theses/Dissertations

1994

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Articles 1 - 27 of 27

Full-Text Articles in Biomedical Engineering and Bioengineering

Wear And Friction Of Hylamer And Polyethylene Against Cobalt Chromium A Pin-On-Disc Study, Jerry D'Alessio, Ii Dec 1994

Wear And Friction Of Hylamer And Polyethylene Against Cobalt Chromium A Pin-On-Disc Study, Jerry D'Alessio, Ii

Theses

Understanding friction and wear of biomaterials is essential to the success of any prosthetic joint. A pin-on-disc wear tester is used to find the friction and wear of pins of one material on a coupon of medical grade cobalt chrome. In this experiment six pins of UHMWPe (ultra high molecular weight polyethylene) and six pins of Hylamer® from Du Pont Manufacturing were tested. Four separate runs were made. The tests were performed for ten million cycles, stopping every one to one and a half million cycles for data acquisition. Volumetric wear, wear rate, and coefficients of friction were measured. Both ...


Time Domain And Frequency Domain Analysis Of Myoelectric Signals During Muscle Fatigue, Rakesh M. Maniar Dec 1994

Time Domain And Frequency Domain Analysis Of Myoelectric Signals During Muscle Fatigue, Rakesh M. Maniar

Theses

Spectral analysis of the EMG signal is a useful tool for studying the complex phenomena of fatigue. The spectral parameters of mean frequency and median frequency, and the time domain parameter of root mean square have been used to measure localized fatigue.

The normal values of median frequency and its decline with fatigue have not as yet been determined in healthy subjects. This should be done in order to apply spectral analysis for clinical evaluations of abnormal populations. Normal median frequency values and its slope were established in this work for the upper extremity muscles of biceps, triceps and deltoid ...


Model Parameter Identification For Rod And Cone Oscillatory Potentials, Kehur Banker Dec 1994

Model Parameter Identification For Rod And Cone Oscillatory Potentials, Kehur Banker

Theses

The use of signal modeling of the oscillatory potential (OP) of the electroretinogram (ERG), in the study of cone-rod interaction is investigated. ERG response data were analyzed for red, orange, blue and white flashes on no background and with red flashes on a blue background (to suppress rod responses). The OP signals were extracted from the ERG by digital bandpass filtering and a signal model was fitted through a simplex algorithm to produce the parameters including "OP envelope-amplitude", latency in terms of "center-time" of the OP-envelope and OP frequency. Amplitude for red flashes with or without a blue background showed ...


Wear Of Polyethylene And Hylamer On Cobalt-Chromium : A Knee Simulator Study, Alessandro F. Canonaco Dec 1994

Wear Of Polyethylene And Hylamer On Cobalt-Chromium : A Knee Simulator Study, Alessandro F. Canonaco

Theses

Two tests were conducted to examine the wear characteristics of tibial bearings used in total knee replacement systems. Each test consisted of six A/P Glide Tibial Bearings each having a conical control arm. The plastic portion of the conical bearings were all made of UHMWPe. Each of these bearing systems was mounted onto a Co-Cr alloy tibial platform and Co-Cr alloy LCS (low contact stress) femoral component . These test samples were mounted onto the New Jersey Mark III Knee Simulator System. The simulator was configured to produce flexion and axial rotation to simulates normal gait. Each test ran at ...


A Pharmacokinetic Model Of The Liver, Samirbhai Rameshbhai Patel Dec 1994

A Pharmacokinetic Model Of The Liver, Samirbhai Rameshbhai Patel

Theses

The liver is the major organ where chemical breakdown of organic and inorganic compounds takes place. A pharmacokinetic heterogeneous model was developed for the local anesthetic and antiarrhythmic drug lidocaine. It was assumed that transport and elimination of lidocaine and its metabolites are linear with concentration. Simulations were done using VisSim software on a 486 based personal computer to obtain concentration profiles for hepatic clearance and for step input of the drug and its metabolites. It was found that the rate of uptake and rate of breakdown were 0.48 min-1 and 0.49 min-1 respectively for lidocaine ...


Measurement Of The Reaction To Stress And Meditation Using Brain Wave Coherence And Heart Rate Variability, Christopher B. King Dec 1994

Measurement Of The Reaction To Stress And Meditation Using Brain Wave Coherence And Heart Rate Variability, Christopher B. King

Theses

Measurement of physiological parameters associated with the stress response and the relaxation response caused by various forms of meditation can provide valuable information about the reaction of the body to the mind and to the external environment.

This study used two different techniques to evaluate physiological parameters. The first part examined the meditation response by recording the EEG and calculating the coherence between brain waves originating from different parts of the brain. It was found that high levels of coherence in the alpha portion of the EEG frequency band coincided with a restful state associated with the relaxation response. In ...


Area And Perimeter Measurements Of Cells With Bound Fluorescent Antibodies, Aicha Weiss Dec 1994

Area And Perimeter Measurements Of Cells With Bound Fluorescent Antibodies, Aicha Weiss

Theses

The objective of this research was to geometrically analyze the characteristics of cells, specifically area and perimeter. The images were transferred from HP A900 system to an AVS work station. The images were visualized and manipulated by the AVS which permits the distinction between the cell body, fluorescent object, and background. The intrinsic geometry of the cell was determined by using image processing algorithms written in C. The images were then passed through a threshold filter, thereby yielding a black background and a white cell body. The perimeter calculation was then applied to the black and white images. Two test ...


Preoperative Risk Assessment For Cardiac Surgery Using Piecewise Linear Regression Model, Arifa Zafar Dec 1994

Preoperative Risk Assessment For Cardiac Surgery Using Piecewise Linear Regression Model, Arifa Zafar

Theses

In the present climate of quality assurance policies, rigorous requirements for informed consent, and a constantly changing patient population, a system of preoperative risk assignment for cardiovascular surgery was developed to monitor and evaluate surgical outcomes. The goal of this work is to estimate the preoperative risk associated with cardiac bypass surgery for patients in different risk categories. These risk categories are determined by the Parsonnet model which is based upon studying the severity of illness. The Parsonnet model assigns a risk value to a range of risk factors consisting of patient attributes and disease parameters. The aggregate of these ...


Development Of A Multi-Lead Trans-Thoracic Impedance Pneumograph For Heart Rate Variability Studies, Curtis Bashford Dec 1994

Development Of A Multi-Lead Trans-Thoracic Impedance Pneumograph For Heart Rate Variability Studies, Curtis Bashford

Theses

In this study, a device that measures respiratory tidal volume and ECG for use in heart rate variability studies, was designed, built and tested. The device developed is a Multi-Lead Trans-Thoracic Impedance Pneumograph, which determines tidal volume on a breath by breath basis, utilizing both hardware and software. It uses standard ECG electrodes which provide increased comfort and inability to the subject over traditional spirometry methods. The device operates similar to traditional bipolar impedance pneumographs except that instead of only one lead (electrode pair), four leads are acquired simultaneously using time-division multiplexing; providing data from different locations and vectors on ...


The Effects Of Elevated Glucose Upon Na+/K+-Atpase In Bovine Retinal Pigment Epithelial Cells, Julie Y. Crider Dec 1994

The Effects Of Elevated Glucose Upon Na+/K+-Atpase In Bovine Retinal Pigment Epithelial Cells, Julie Y. Crider

Theses and Dissertations

Crider, Julie Y., The Effects of Elevated Glucose Upon Na+/K+-ATPase in Bovine Retinal Pigment Epithelial Cells. Doctor of Philosophy (Biomedical Sciences, Pharmacology), December, 1994, 154 pp., 14 tables, 31 illustrations, bibliography, 288 titles. Bovine retinal pigment epithelial (RPE) cells were cultured under 1, 4.5 and 10 g/l glucose conditions in order to characterize the effects of hyperglycemia upon Na+/K+-ATPase. Functional activity of Na+/K+-ATPase was measured as ouabain-sensitive Rb+ uptake. 3H ouabain was used to assess binding characteristics of Na+/K+-ATPase. The major contributors to rubidium (mRb+) uptake activity were the ouabain-sensitive ...


Computerized Scoring Of Sleep Stage Data / By Subbarao Narayana, Subbarao Narayana Oct 1994

Computerized Scoring Of Sleep Stage Data / By Subbarao Narayana, Subbarao Narayana

Theses

Sleep is a non-uniform biological state which has been subdivided into different stages. The basic criteria behind staging are the amplitude and frequency variations of sleep data. The sleep analysis is carried out by considering the characteristic variation of all three EEG, EOG and EMG signals. The polygraphic recording of nocturnal sleep is a method of research widely used in neurophysiology laboratories, both for the clinical study of sleep and for the evaluation of the therapeutic effectiveness of drugs acting on sleep. The analysis of this method is carried out by an expert individual whose depth of knowledge regarding the ...


Autonomic Nervous System Evaluation Using Time-Frequency Analysis, Sanjay Fernando Oct 1994

Autonomic Nervous System Evaluation Using Time-Frequency Analysis, Sanjay Fernando

Theses

Spectral analysis of heartrate variability (HRV) provided an estimate of the sympathetic and parasympatheticinfluences on heart rate without drugs or other invasive procedures.However, there are many situations where heart rate changed rapidlyover time and the control of those changes was of considerable interest.Time-frequency analysis was utilized to expand the concept of spectralanalysis of HRV to describe changes in vagal tone and sympatho-vagalbalance as a function of time. As a result the assessment of the autonomicnervous system during rapid changes in heart rate was made.

There were three advantagesto calculating vagal tone and sympatho-vagal balance by using timefrequencyanalysis. First ...


Characterization Of Sleep Eeg, Seetharamiah Sateesh Oct 1994

Characterization Of Sleep Eeg, Seetharamiah Sateesh

Theses

The physiological relationship between the various components of sleep and its variation due to drug administration has been used as one of the primary tools to analyze the performance of drug. A number of studies have been performed in recent years in this direction. Electroencephalogram (EEG) has been characterized with the help of variables ranging from measurements of the duration of different sleep stages to the activities that define the stages themselves. Advances in computer hardware and software have improved the methods of data acquisition and storage. Analysis of long stretch of data has always been a problem considering the ...


Cervical Spine Bone Anchoring System Csbas Pullout Testing And Comparisons, Konstantin Caploon Oct 1994

Cervical Spine Bone Anchoring System Csbas Pullout Testing And Comparisons, Konstantin Caploon

Theses

The purpose of this study is to prove the effectiveness of the newly designed and patented Cervical Spine Bone Anchoring System (CSBAS). It is a posterior fixation device intended to be used with spine bone-plate systems. Its purposes are to substitute for conventional bone screws, significantly decrease the neurological and vascular risks associated with screws, and have comparable bone purchase strength.

Three CSBAS sizes (10mm, 12mm, and 14mm) were compared to four conventional bone screws in six human cadaveric cervical spines (C2-C7). Post-implantation axial pullout tests of each device using an MTS servohydraulic testing machine yielded bone purchase strength.

In ...


Modeling, Simulation And Hemodynamic Response Analysis Of Arteriovenous Malformation Occlusion, Huijuan Mao May 1994

Modeling, Simulation And Hemodynamic Response Analysis Of Arteriovenous Malformation Occlusion, Huijuan Mao

Theses

The cerebral Arteriovenous Malformation system (AVM) or fistula, is a network with large caliber vessels that yields an alternate pathway for blood flow between arteries and veins. Neurosurgical and interventional radiological techniques are the common way to treat AVM patients so that the normal capillary blood flow would be restored. Several patients who underwent this procedure had different degrees of brain swelling and subsequent hemorrhage. To understand this, Blesser et al. developed a simplified model to simulate the effect of AVM occlusion on cerebrovascular pressure and flow. Their model does not include the cerebrovascular regulatory mechanism which is an important ...


Reconstruction And Enhancement Of Medical Computed Tomography Images, Manoj K. Pattahil Jan 1994

Reconstruction And Enhancement Of Medical Computed Tomography Images, Manoj K. Pattahil

Theses

The aim of Computed Tomography is to obtain information regarding the nature of the materials occupying precise positions inside the body. But due to errors in the projection data, which arise due to errors in measurement, beam hardening, missing data and noise, the reconstructed image has artifacts which reduces its diagnostic value. Thus the image obtained has to be processed to remove these artifacts and to improve the quality of the image. This is achieved by iterative reconstruction along with different post-reconstruction processing. Iterative reconstruction is done by repeating the process of projecting the image and creating new projection data ...


In Vitro Testing And Evaluation Of Intraaortic And Extraaortic Balloon Counterpulsation Devices, Joseph V. Izzo Jan 1994

In Vitro Testing And Evaluation Of Intraaortic And Extraaortic Balloon Counterpulsation Devices, Joseph V. Izzo

Theses

The primary purpose of this project was to develop an in vitro environment in which the intraaortic and extra-aortic balloon pumps could be tested and evaluated. This was done by modifying a mechanical heart simulator -- the pulse duplicator system -- to accommodate both devices, and developing a software system that could collect and process the data relevant to the operation of the two balloons.

Both counterpulsation techniques were tested in the pulse duplicator where the aortic pressure and flow data were collected. The software system then processes the data to calculate all of the parameters affected by counterpulsation.

While the results ...


The Production Of Textile Fibers From Soy Proteins , Hsin-Chi Huang Jan 1994

The Production Of Textile Fibers From Soy Proteins , Hsin-Chi Huang

Retrospective Theses and Dissertations

The use of soy protein presently is limited mostly to animal feeds, but the markets for soy protein could be expanded by industrial applications. In these studies, soy fibers were produced from soy protein isolate using both wet spinning and extrusion methods. The wet spinning process consisted of forcing an aged alkaline protein solution through a spinnerette having 368-[mu] openings into an acid coagulating bath. The extrusion process employed a twin screw extruder to force a protein-water mixture with "dough-like" consistency through a die also with 368-[mu] openings. The physical properties of the fibers were measured at 11 ...


Modeling Joint Kinetics In The Tkatchev Release Move , Martha Nichols-Ketchum Jan 1994

Modeling Joint Kinetics In The Tkatchev Release Move , Martha Nichols-Ketchum

Retrospective Theses and Dissertations

This study developed a three-dimensional computer simulation model of the Tkatchev release move on the men's horizontal bar. The model used the Hanavan human body model and the inverse dynamics approach to predict resultant forces and torques at the joints during performance. The model was used to determine aspects of the performance that contribute to the risk of injury and to determine strength and flexibility requirements for the skill;This study was done in two parts. In Part 1, kinetic parameters were calculated from actual performances of Tkatchevs. Two college-level male gymnasts each performed 9-10 Tkatchevs during a single ...


Water And Electrolyte Regulation During Space Flight And Exercise , Susan Elizabeth Doty Jan 1994

Water And Electrolyte Regulation During Space Flight And Exercise , Susan Elizabeth Doty

Retrospective Theses and Dissertations

When one is exposed to microgravity, fluid which is normally pooled in the lower extremities is redistributed headward and weight bearing bones begin to demineralize due to reduced mechanical stresses. The kidney, which is the primary regulator of body fluid volume and composition, responds to the fluid shift and bone demineralization by increasing the urinary output of water, sodium, and calcium. This research involves developing a mathematical description of how water and electrolytes are internally redistributed and exchanged with the environment during space flight. Various levels of activity are also considered, since it is believed that exercise can prevent some ...


Medical Image Tomography: A Statistically Tailored Neural Network Approach , John Patrick Kerr Jan 1994

Medical Image Tomography: A Statistically Tailored Neural Network Approach , John Patrick Kerr

Retrospective Theses and Dissertations

In medical computed tomography (CT) the tomographic images are reconstructed from planar information collected 180∘ to 360∘ around the patient. In clinical applications, the reconstructions are typically produced using a filtered backprojection algorithm. Filtered backprojection methods have limitations that create a high percentage of statistical uncertainty in the reconstructed images. Many techniques have been developed which produce better reconstructions, but they tend to be computationally expensive, and thus, impractical for clinical use;Artificial neural networks (ANN) have been shown to be adept at learning and then simulating complex functional relationships. For medical tomography, a neural network can be trained to ...


Evaluation Of A Direct Systolic Cardiac Augmentation Device On A Canine Heart During Global Postischemic Dysfunction , Raymond Kenneth Kudej Jan 1994

Evaluation Of A Direct Systolic Cardiac Augmentation Device On A Canine Heart During Global Postischemic Dysfunction , Raymond Kenneth Kudej

Retrospective Theses and Dissertations

The performance of a direct systolic cardiac augmentation device, called a heart cuff, was evaluated during application of the device to canine hearts following a period of global ischemia. The heart cuff was developed to provide temporary, partial assistance to a heart experiencing postischemic myocardial dysfunction (myocardial stunning);Myocardial stunning is a postischemic mechanical dysfunction which results from a sublethal tissue injury occurring at the time of reperfusion. The injury will resolve if the myocardial tissue is given sufficient time to recover. Stunning may significantly contribute to the morbidity and mortality of many cardiac procedures because of the temporary inability ...


An Investigation Into The Role Of Arterial Wall Vibration In The Pathogenesis Of Atherosclerosis , Becky Bellatti Bittle Jan 1994

An Investigation Into The Role Of Arterial Wall Vibration In The Pathogenesis Of Atherosclerosis , Becky Bellatti Bittle

Retrospective Theses and Dissertations

Fifty percent of all the deaths in the Western world can be attributed to diseases of the cardiovascular system. A major player amongst these diseases is atherosclerosis. Atherosclerosis is the localized thickening of the arterial wall and is primarily due to the proliferation of fibrous tissue and smooth muscle cells in conjunction with the deposition of lipids within the wall. The hypothesis investigated was that high frequency, low amplitude vibratory environments similar to those found in regions of disturbed flow, which are coincident with intimal thickenings, the earliest stage of atherosclerosis, do elicit a proliferative response in vascular smooth muscle ...


Study Of The Interaction Of Silica-Based Nd: Yag Laser Optical Fibers With Tissue , Sheila Ann Olejniczak Grant Jan 1994

Study Of The Interaction Of Silica-Based Nd: Yag Laser Optical Fibers With Tissue , Sheila Ann Olejniczak Grant

Retrospective Theses and Dissertations

During laser surgery, light from a Nd:YAG laser can be transmitted through a silica optical fiber. As long as the fiber tip does not contact tissue, it remains in near pristine condition and transmits the laser light to cause a photocoagulative tissue effect. Once the tip contacts tissue; however, degradation of the tip occurs and transmission of the laser energy is decreased. The laser energy is absorbed at the contact tip causing it to heat up. In this condition the tip can only be used for tissue incision or ablation. The process of damaging the tip has been termed ...


Patient, Disease And Surgical Parameters In The Prediction Of Histologic Nodes And Recurrence Of Squamous Cell Carcinoma, Adolfo A. Ferreira Jan 1994

Patient, Disease And Surgical Parameters In The Prediction Of Histologic Nodes And Recurrence Of Squamous Cell Carcinoma, Adolfo A. Ferreira

Theses

This research explores the impact of a variety patient, disease and lesion parameters upon the probability of post surgery recurrence of squamous cell carcinoma and the involvement of histologic nodes. It was found that parameters such as number of nodes, Lymph Vascular Space Invasion (LVS), figo stage, growth rate and host response as well as tumor thickness, depth of invasion and lesion size are good predictors. Other parameters such as cell type and condylomas were found to correlate minimally with recurrence and histologic nodes. Surgical parameters such as surgical margin and distance surgical margin were found to have poor correlation ...


Three Dimensional Diaphragm Simulation Model For The Relationship Of The Tension, Pressure And Shape, Zhangming He Jan 1994

Three Dimensional Diaphragm Simulation Model For The Relationship Of The Tension, Pressure And Shape, Zhangming He

Theses

Weakness of inspiratory muscles is a major cause of respiratory failure. There are many clinical circumstances in which it may occur. The diaphragm is a major respiratory muscle. It has been difficult to quantify its shape, curvature and length.

To solve this question, a three dimensional diaphragm equation was derived on the, assumption that the diaphragm is only attached at its periphery to the rib cage and the abdomen is filled with fluid. Computer programs were developed to fit the equation to the diaphragm contours obtained from plane X rays.

The results indicate that the ratio of transdiaphragmatic pressure to ...


Laborconsult : An Expert System For Evaluating Fetal Heart Rate And The Progress Of Labor, Wendy Raymond-Fink Jan 1994

Laborconsult : An Expert System For Evaluating Fetal Heart Rate And The Progress Of Labor, Wendy Raymond-Fink

Theses

LaborConsult is a rule-based expert system designed to aid the non-expert practitioner in monitoring the progress and fetal tolerance of labor. The expert system obtains from the user the values of the following labor variables: cervical dilatation, fetal station, and the time between and duration of uterine contractions. The rates of cervical dilatation and fetal descent are then calculated and compared to labor standards. Additionally, the consultation assists the user in the analysis of electronic fetal monitor tracings.

The expert system development tool VP-Expert allows the interfacing of the consultation with the spreadsheet Lotus 1-2-3. This enables the creation of ...