This research investigates the performance of Code Division Multiple Access (CDMA) cellular communication systems employing adaptive antennas at the base station. First, a simple analysis is presented which shows that significant improvements in performance can be obtained by using directional antennas in the mobile-to-base station link of CDMA cellular radio systems. Next, steps are taken to improve the analysis of CDMA systems employing adaptive antennas. The first step in improving the analysis is to develop new analytical bit error rate estimation tools which are much more accurate than previous expressions when power control is imperfect, when intercell interference degrades system performance, and when directional antennas are used at one end of the CDMA radio link. These expressions are further extended to accommodate multipath radio channels when omni-directional antennas, fixed directional antennas, or adaptive antennas are applied at either end of the link. This dissertation also develops a channel model which may be used to simulate the direction-of-arrival (DOA) as well as the time-of-arrival (TOA) and power level of multipath components. These analysis techniques are used to develop a simulation framework which can model the performance of CDMA systems, incorporating the effects of the multipath channel, optimal adaptive antenna arrays, and more accurate bit error rate expressions. Results from these simulations, and the impact of these results on future CDMA cellular systems, are described in this dissertation. / Ph. D.

Saturated fat is considered one of the most important dietary components that should be decreased when attempting to lower plasma total cholesterol (TC). However, it has been suggested that stearic acid (18:0) does not increase plasma TC and should not be grouped with other saturated fatty acids: lauric (12:0), myristic (14:0) and palmitic (16:0), (LMP). Red meat contains a high amount of stearic acid, while dairy products are high in the LMP fatty acids. Since both of these food sources make up a significant part of the American diet, knowing the effects of these different fat sources on the plasma total and lipoprotein cholesterol levels relative to one another is important. Eleven males (22 - 35 y) followed three dietary treatments for four weeks each, separated by a two week wash-out period before crossing over and starting the next dietary treatment. The three dietary treatments were: Beef, Dairy, and Olive Oil. All diets were similar in macronutrient components (37% fat, 13% protein, and 50% carbohydrate). The Beef Diet and the Dairy Diet had a P/M/S ratio of 0.4/1.0/1.0 while the Olive Oil Diet had a P/M/S ratio of 0.4/2.0/1.0. The subjects followed a prescribed menu during the experimental diet periods and kept daily food records during both the experimental periods and the wash-out periods. Twelve-hour fasting blood samples were collected every two weeks during the 18 weeks of the study for a total of ten samples. Plasma was analyzed for TC, high density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels using enzymatic, colorimetric methods. There were no significant changes in any of the plasma cholesterol or lipoprotein measurements during the Beef Diet or the Dairy Diet. Mean plasma TC decreased progressively during the Olive Oil Diet: 186 (± 26) mg/dl at baseline, 178 (± 23) mg/dl after 2 weeks, and 174 (± 30) mg/dl after 4 weeks (p<0.05). The lack of any significant change in plasma cholesterol values for the Beef Diet or the Dairy Diet may have been due to a combination of matching the M/S ratios, and the smaller than anticipated difference in the stearic acid content between the two diets. / M.S.

Extractives of Western Juniper (Juniperus occidentalis) have been isolated and separated by chromatographic means. Since this species is durable, bioactivity of several fractions has been determined. The bioactivity has been determined by the brine shrimp lethal bioassay. Less polar compounds with a low molecular weight average possess a high toxicity therefore contribute to the overall durability of this species. More polar fractions with higher molecular weight averages are non-toxic. The polymeric material with M_w = 13,550 g/mole, termed phlobaphene, has been purified. The analyses of western juniper phlobaphene by Fourier Transformed Infrared spectroscopy and 2D HMBC NMR (two dimensional Heteronuclear Multiple Bond Correlation) show that this is a heterogeneous polymeric material which reveals three long-range correlations. A long range labelled carbonyl correlation at around δ = 6.00 ppm corresponding to α-proton of β-O-4 type ether structures which is comparable to similar correlations found in lignins. The two other long-range correlations at around δ = 5.00 ppm and δ = 5.30 ppm are not assignable to any lignin-like structure. The 2D HMBC experiment can be used as an improved quantitative NMR technique for the assessment of labelled lignins and phlobaphenes. The ¹³C NMR has a potential applicability as an improved technique for quantitative analyses of labelled lignins. / M.S.

The literature which exists concerning cardiovascular reactivity is limited in terms of its applicability to African American males' responses to such chronic stressors as racism. The present study set forth to study empirically the cognitive and physiological responsivity of young African American males to racially noxious stimuli. Given that African American males tend to have higher resting blood pressures, show greater cardiovascular reactiivity, and suffer the highest rate of essential hypertension, they were chosen as the target group for the present study. 45 African American male students at Virginia Polytechnic Institute and State University were compared on a series of objective physiological and psychological measures in order to investigate the mediating impact of cognitive appraisal, anger expression, hostility, and masculine gender role stress upon cardiovascular reactivity. While none of the hypothesized relationships emerged at a level of statistical significance, a number of interesting trends emerged. For instance, as in other related research, diastolic blood pressure and heart rate approached significance in several relationships. Further, support was established for the use of continuous measurement of cardiovascular output. / M.S.

Conventional fiber-optic interferometers suffer from limitations that prevent real-time, absolute sensing of weak perturbations. A new sensing system that overcomes the above drawbacks by using a broadband light source, high-finesse/small-gap extrinsic Fabry-Perot cavity, and a novel demodulation scheme is proposed. The principle of operation is based on the large spectral displacement of an intensity peak, in the transmitted output pattern, due to minute changes in cavity length of a small-gap/high-finesse cavity. The direction and magnitude of the shift of a high-finesse peak is directly proportional to that of the applied perturbation. The basic features and principle of operation are studied in detail, and experiments that demonstrate temperature resolutions of 0.015 °C, and strain resolutions of 0.03 µz are performed. The high sensitivity of the sensing system is used to detect acoustic waves when the output is demodulated in the time domain. A theoretical analysis of surface acoustic waves is conducted. Experiments on directional sensitivity, gage length sensitivity and pencil lead-break tests are performed, and signal-to noise ratios of the order of 42 dB are demonstrated. A new demodulation scheme using dual-mode fiber to increase the sensitivity of the system is proposed. The principle of operation of the demodulation scheme is analyzed, and preliminary proof-of-concept experiments for temperature and strain perturbations are conducted. Detection of acoustic signals that are weaker by three orders of magnitude, and temperature and strain resolutions that are better by two orders of magnitude are predicted. / M.S.

Endocrine changes and recovered oocytes were evaluated during 16 wk of ultrasound-guided transvaginal follicular aspiration (TVF A) and prior to and following administration of GnRH at the cessation ofTVFA. Previously aspirated (PAC, n = 4) and non-aspirated, non-lactating (AC, n = 4) Holstein cows were subjected to 16 wk of twice-weekly TVFA. Four control cows (OAC) were aspirated one time only at the final TVFA session (wk 16). The PAC and AC cows averaged 3.4 ± 1.2 (± SE) and 6.8 ± 1.2 oocytes/session, respectively. Progesterone in OAC was 4.5 ± .2 ng/mL before TVFA, while the PAC and AC averaged .5 ± .2 and .3 ± .2 ng/mL, respectively, at wk 16. LH was 1.0 ± .2 ng/mL at wk 16 and increased to 7. 5 ± .1 ng/mL after GnRH. Follicle numbers after GnRH varied most among treatment groups for follicles < 9 mm. The LH concentrations for the period following the final TVF A session were associated with increased numbers of peaks and peak frequencies in the PAC when compared to OAC, and the interval between peaks is increased in the PAC and AC. These results suggest that long-term TVF A affects progesterone and LH profiles and ovarian dynamics in cows. A second objective was to determine if platelet-derived growth factor (PDGF-BB) and leukemia inhibitory factor (LIF) exhibit a stimulatory effect during in vitro co-culture with Buffalo Rat liver cells (BRL). Oocytes were matured in transit, fertilized in vitro, and embryos were co-cultured with BRL cells for 7 d. The treatment groups were as follows: treatment 1 = 1 ng/mL PDGF-BB, where PDGF-BB is the human recombinant homodimer of the B chain; treatment 2 = 1 ng/mL LIF; treatment 3 = .5 ng/mL PDGF-BB + .5 ng/mL LIF; treatment 4 = 1 ng/mL PDGF-BB + 1 ng/mL LIF; and treatment 5 = control group cultured in modified TCM 1 99 alone. Morulae and blastocyst development was decreased with the addition of 1 ng/mL PDGF-BB (12.4%) and with the addition of .5 ng/mL PDGF-BB and .5 ng/mL LIF (11.7%) when compared with control development (23.3%). These results indicate the addition of PDGF alone and low amounts of PDGF and LIF to the BRL cell co-culture system for bovine zygotes provides an inhibitory effect on the developmental rates. A combination of 1 ng/mL PDGF and 1 ng/mL LIF and LIF alone exerted a neutral effect on development, suggesting BRL cell co-culture is not enhanced by addition of these growth factors. / M.S.

Optical fiber Bragg gratings, first demonstrated by Hill in 1978 [1], will see increasing deployment as sensors in smart structure applications due to their minimal insertion loss and small profile. Bragg grating sensors provide narrowband reflections from a periodic index discontinuity. Strain and temperature changes occurring on the grating induce a shift in the reflected wavelength and monitoring the wavelength shift provides a indication of the strength of the perturbation. Currently, the most basic Bragg grating demodulation system consists of monitoring the reflected wavelength with an optical spectrum analyzer (OSA), but use of these devices is limited due to high costs and poor frequency response. In this thesis, recent reported demodulation schemes are compared and a novel interrogation system using dual-mode optical fiber as an intensity-based demodulator is proposed. The modal birefringence of the dual-mode fiber is wavelength dependent and therefore, the modal phase relationship changes as a function of the Bragg grating reflected wavelength. Monitoring the spatially-filtered output from the dual-mode fiber produces a real-time, sinusoidally varying intensity signal. The optical architecture for this demodulation system is described and experimental data for temperature, strain, and vibration response is provided. It is predicted that with an optical source operating at 300 microwatts, less than 1 microstrain resolution is achievable. / M.S.

This thesis presents a computer based simultaneous engineering design evaluation methodology to simultaneously evaluate candidate product and manufacturing resource designs. It utilizes the design dependent parameter approach to evaluate design alternatives resulting from candidate product and manufacturing resource designs. The evaluation measure used is expected profit. A linear, mixed integer, single period, simultaneous engineering design evaluation model is developed to evaluate design alternatives, comprising candidate product and manufacturing resource designs, using a design evaluation function. The design evaluation function utilizes a linear optimization based search to evaluate each design alternative. An integrated menu based software application, called SEDE 1.0, is developed to implement the design evaluation model. It integrates XPRESS-MP, a modeling language and solver, and Paradox 3.5 for DOS, a relational database management system. The application provides for ease of data handling in that input data is entered, edited, manipulated, and stored in Paradox tables. It is then read directly by the modeler at the time of matrix generation. The design evaluation model is then applied to the constrained-design problem wherein the design alternatives for the products as well as the production resources are limited. In this case, a complete, a priori, enumeration of all feasible design alternatives is possible. The constrained-design evaluation model includes design alternatives for both, products as well as manufacturing resources. It merges the design space into the optimization space. / M.S.

Researchers have indicated that nutrition students constitute a subgroup of the university population at a higher risk of developing eating disorders. Individuals may be drawn to study nutrition because of pre-existing food-related problems, or problems may arise once individuals enter the field due to peer pressure. The purpose of this research was to determine the period of education at which nutrition students and professionals exhibit the greatest incidence of potential disordered eating. The sample consisted of female, undergraduate students majoring in nutrition and accounting (control group); and registered dietitians. Student groups were subdivided into underclassmen and upperclassmen. A survey packet containing the Eating Disorders Inventory-2 (EDI-2) and a behavior questionnaire were mailed to all subjects. Lifetime and current incidence of dieting, binge eating and self-induced vomiting were similar between the groups. Dietitians were least likely to feel peer pressure to be thin (p<.004) and expressed less weight concern (p<.001) than the student groups. Underclassmen exhibited the highest degree of drive for thinness, which differed from dietitians (p<.004) but was similar to upperclassmen nutrition students. Overall, EDI subscale scores for all groups were comparable to the normative data for college-age women. As a whole, nutrition students exercised more frequently than dietitians or accounting students (p<.004). The motivation behind this activity needs further examination. The field of nutrition does not seem to attract students with a greater predisposition towards eating disorders, nor does peer pressure within the field appear to be prevalent. / M.S.

Sulfonated azo compounds are one of the most commonly used textile dyes. They pose an environmental problem because they can be difficult to degrade in municipal and industrial treatment systems and can cause effluent wastewaters to violate color standards. Methods were developed to monitor for three reactive azo dyes: Remazol Black B, Remazol Red RB, and Remazol Golden Yellow 3RA, and their degradation products. HPLC/ diode array detector, GC/MS, and LC/MS were utilized to characterize the purified dyes and the wastewaters and identify degradation products of the dyes resulting from several biological and chemical treatment processes. Results indicate that chemical reduction and anaerobic biological treatment of the dyes both result in cleavage of the azo bonds and formation of aromatic amines such as p-(2-hydroxyethylsulfone)-aniline, a reduction product of all three dyes. Some of these amines were unstable and quickly reacted to form other chemical structures. The textile mill effluent contained about thirty organic compounds detectable by GC/MS, including p-(2-hydroxyethylsulfone)-aniline. Anaerobic treatment caused little degradation of these compounds, but aerobic treatment degraded most of them. This research only investigated wastewater from a textile facility which performed pad dyeing of the cotton in a cotton/polyester blend. The sulfonated azo dyes used were reactive dyes typically applied to cotton fabrics. / M.S.