Engineering Commons^™

Effect Of Fiber-Matrix Coupling On The Mechanical Properties Of A Totally Bioabsorbable Composite, Barbaro Jesus Perez

Theses

The mechanical properties of a new class of bioabsorbable polymer-composite based on the amino acid tyrosine and calcium phosphate fibers were studied. The effect of the fiber aspect ratio on the elastic modulus of a discontinuous fiber composite was analyzed using the SMC composite micromechanics computer model. The mechanical stiffness of this polymer was found to be superior to that of poly-p-dioxanone, caprolactone and poly-o-ester.

The fiber surface was modified with methane plasma spray to improve the fiber-matrix coupling. The treated fiber composites had 16-40% higher tensile modulus than the untreated fiber composites. From the flexural test results it is …

Application Of Signal Processing Techniques For Measurement Of Muscle Fiber Conduction Velocity, Satheesh Kumar Swaminathan

Theses

The objectives of this study were to evaluate if muscle fiber conduction velocity (MFCV) could be used as a reliable indicator of fatigue and to characterize the recovery of MFCV after a fatiguing contraction. The decline of MFCV with fatigue was modelled using linear regression and compared with the decline in median frequency (MF). It was found that the percent decline in MF with fatigue was greater than that of MFCV with fatigue and that the decline of MFCV was consistent in all subjects tested. It was thus determined that MFCV could be used as a reliable indicator of fatigue. …

The Morphology Of Uhmwpe Wear Debris Generated By A Hip Joint Simulator, Aaron P. Essner

Theses

The size, quantity and shape of total hip replacement wear debris may identify wear mechanisms as well as play a role in osteolysis. Characterization of wear particles generated from a hip joint simulator was conducted followed by comparison with literature reported in vivo results. The effect of counterface material and lubricant type on particle morphology was assessed. Biomaterial pairs including UHMWPE articulated against CoCr, Alumina and Zirconia were considered. Deionized (D.I.) water and bovine serum were used as lubricants. Particles generated from Alumina/UHMWPE in serum were slightly larger than those for CoCr and Zirconia against UHMWPE in serum. Particle shape …

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 …

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 …

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

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 …

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

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 …

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 …

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 …

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 …

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. The results …