The purpose of this study was to evaluate the physical properties of dental sealant resins under aging conditions to determine the critical factors controlling functional property loss with time. The effect of processing on the chemical and thermal properties of several different sealant formulations was evaluated. These processing parameters included the blue light exposure time for each light-curing system and time after illumination. The results indicate that the level of cure for each system was incomplete at the end of all processing procedures. Heating as well as further aging of the cured resin advanced the cure. Additionally, one of our goal was to model the curing characteristics of the sealant as a function of depth in the fissure to evaluate the thickness influence on the sealant mechanical properties. The strength and stiffness of the light-cured sealant varied as a function of depth in the fissure. This results in a gradient of deformation which could cause early fracture of the resin upon chewing. Incomplete resin conversion is important since dental adhesives have been shown to be leached by saliva and the elution products have been recently shown to be potentially estrogenic. Samples of differently processed commercial sealants were immersed in an ethanol/water solution and extractions were analyzed by HPLC. An inverse correlation between the degree of cure and the % of elution as well as high level of extraction was found. An <i>in vivo</i> study has been performed on fifteen pigs. The purpose of the experiment is to obtain data on <i>in vivo</i> sealing ability of the sealant. Low sealant retention rates have been found but interesting observations of sealed fissures were made and the pig can be considered like an acceptable model. / Master of Science

The purpose of this study was to describe nutritional screening practices in hospital settings in Virginia. A questionnaire was mailed to each of the chief clinical dietitians employed at 123 Virginia hospitals listed in the 1994 American Hospital Guide (22). Ninety-one (74%) responses were received. Twenty-five (27.5 %) of the hospitals included in the survey were considered large hospitals with more than 300 licensed beds and 66 (72.5 %) were small hospitals with 300 or fewer licensed beds. Re-screening of patients occurred in 40 (60.6 %) of the small hospitals while 8 (32 %) of the large hospitals had re-screening policies. Computers were used for nutritional screening in 17 (68 %) of the large hospitals and 13 (19.7 %) of the small hospitals. Dietetic technicians participated in screening in 10 (40 %) of the large hospitals and in 11 (16.9 %) of the small hospitals. Dietetic students participated in screening in 8 (32 %) of the large hospitals and they participated in 3 (4.5 %) of the small hospitals. Hemoglobin was used in 6 (24 %) of the large hospitals to determine a patients nutritional risk. It was used in 34 (51.5 %) of the small hospitals. Hematocrit was used in 36 (54.5 %) of the small hospitals and in 5 (20 %) of the large hospitals. All of these associations between large and small hospitals were significantly different (p < .05 ) as determined by Chi square analysis. Since there were no other significant associations between large and small hospitals, the reminder of the results were treated as one group of hospitals. Seventy-five (82.4 %) of the hospitals represented in the survey had written screening policies and a standard form was used in 59 (64.8 0/0) of them. Fifteen (16.50/0) of the hospitals surveyed had written screening policies for specialty units; 8 (8.8 %) also had specific forms. The three most common items included in the routine nutritional screening were weight, height, and lab results. Weight and height also were the items most often missing or not available when a routine screening was performed. Albumin was used as an abnormal finding to determine nutritional risk in 79 (86.8 %) of the hospitals; while weight loss was used in 82 (90.1 %) of the hospitals and weight for height was used in 69 (75.8 010) hospitals. / Master of Science

Data for Hispanic participants in the 1985 - 1988 California Adolescent Family Life (AFL) Program were examined to determine whether acculturation level and marital status have an effect on maternal educational outcomes and infant health outcomes. Following Becerra and de Anda (1984) language preference is used as an approximation of acculturation level. With respect to marital status, two models are constructed. In Model 1, marital status includes the values never married or ever married. In Model 2, married and cohabiting women are grouped together and compared with women who neither have married nor cohabited. Logistic regression was used to determine the effect of these independent variables on the dichotomized maternal education and infant health variables. The infant health measures examined in this study are birthweight (low or adequate birthweight) and neonatal intensive care unit admission. More acculturated women were found to be more likely to have babies admitted to the NICU than less acculturated women. More acculturated women were also more likely than less acculturated women to be enrolled or graduated from school at the time they exited the AFL Program. Bivariate analyses for marriage with both birthweight and NICU admission approached significance. The logistic regression analyses for these relationships were not significant. / Master of Science

The oxidation of soluble manganese (Mn(II)) to insoluble manganese dioxide (MnO_x(s)) is fairly well understood; however, the role of ferric hydroxide/oxides (Fe(OH)₃_(s)) in catalyzing the oxidation of Mn(II) by oxidants such as free chlorine (HOCI) is one specific aspect of manganese removal via oxidation that requires further investigation. Data collected in this study indicate that the rate of Mn(II) oxidation may be beneficially catalyzed by the presence of previously formed Fe(OH)₃_(s) particles. The mechanistic means by which this enhanced oxidation is accomplished was the focal point of this research. Specifically, the research objectives were as follows: (1) To study all possible Mn(ID) removal mechanisms for a typical groundwater system to determine the necessary experimental conditions required to isolate the study of Mn(II) oxidation in the presence of ferric hydroxides/oxides (Fe(OH)₃_(s)). (2) To investigate the means by which ferric hydroxides/oxides (Fe(OH)₃_(s)) may enhance the removal of Mn(II) during water treatment by interacting with HOCI; and (3) To develop an engineered system that captures the observed catalyzing effect iron oxides have on Mn(II) oxidation by HOCI citing key system design parameters. To complete these objectives a combination of batch and continuous flow bench-scale experiments were utilized. Batch study results indicated that the primary Mn(II) removal mechanism was a combination of adsorption and oxidation, specifically, adsorption of Mn(II) onto the iron oxide surface where Mn(II) is subsequently oxidized. A continuous flow system was developed to utilize this removal mechanism under water treatment plant conditions to improve the efficiency of iron and manganese removal. The results from experimentation with the continuous flow system indicated the following: ∙ Sufficient free chlorine residual in effluent insures consistent system performance, ∙ Initial iron oxide concentration within reactor system must have adequate adsorption capacity for initial adsorption-oxidation step to occur, ∙ Removal efficiency and reactor stability increase with the accumulation of manganese oxides, and ∙ Solution pH and reactor hydraulics affect system performance significantly. The results suggest that this technology has the potential to change the look of conventional groundwater treatment systems that practice iron and manganese removal. / Master of Science

The Pen Branch Fault is a reactivated, high angle, reverse basin border fault that dips to southeast from the basement (Triassic-Paleozoic-Precambrian in age) to near vertical through the Atlantic Coastal Plain sediments (Late Cretaceous to Recent in age) of the Savannah River site in South Carolina. The fault movement has occurred through Late Cretaceous to Tertiary. Faulting might penetrate as shallow as the Dry Branch and the Tobacco Road Sand Formations (Late Eocene). An investigation with high resolution reflection seismic data is undertaken along the Pen Branch Fault. Five of the seismic lines are reprocessed to help in determining the upward depth of penetration of this fault. This is done by utilizing refracted arrivals from the multifold reflection data. The shallowest refractors (4 - 18 m) imaged have an average velocity of 1700 m/s. All of the lines exhibit events that are not flat lying across the data where the fault is believed to be. The lines possess deformation such as offsets, upwarping and channels. Deformation can be related to the Pen Branch Fault as shallow as 4 m from the surface. Displacements along the lines vary from 1 m up to 5 m. Reverse sense of motion is mainly exhibited along the fault zone that is covered by this study. The events resolved portray the Pen Branch Fault in a fault zone of subparallel faults and splays. / Master of Science

The effects of marginal zinc intake and exercise on the iron status of Sprague-Dawley rats during pregnancy were observed. The dams were assigned to one of four groups: zinc marginal (6.18 ppm zinc sulfate), exercise or sedentary; zinc adequate (37.63 ppm), exercise or sedentary. The dams swam everyday for one hour until day 18. Data was collected on days 15, 18, and 21. Anorexia occurred by day 21 in the zinc marginal groups, significantly reducing dam body and organ weights and may be attributed to maternal tissue mobilization in response to increased fetal zinc demands late in gestation. Fetal and placental weights were unaffected. Hemoglobin and hematocrit decreased throughout gestation in the adequate group, and until day 18 in the marginal group, increasing significantly by day 21. Serum iron, TIBC, and maternal liver iron decreased throughout pregnancy although liver and spleen iron stores were higher in the zinc marginal dams. Fetal iron increased significantly independent of treatment. Increased iron status in the zinc marginal dams may be due to enhanced iron uptake when zinc nutriture is low. Overall decreases in serum iron, TIBC, and liver iron reflect the increasing demands of iron from the fetus. Heart weight was significantly higher in the swimmers. The sedentary group weighed more than the exercise group, their hematocrit increased by day 21, and spleen iron stores were significantly higher. No change in hematocrit was found in the exercise dams and their TIBC was greater, revealing an increase demand for iron during exercise. It was concluded that a zinc marginal intake, its resulting anorexia, and the onset of strenuous exercise at conception, affected maternal iron status and weight without harming the fetus. / Master of Science

A control algorithm is developed and applied to a previously designed tunable vibration absorber. The adaptive vibration absorber is capable of detecting the frequency of the driving force and tuning itself automatically to that particular frequency. The primary structure was previously designed to obtain a certain natural frequency. The absorber structure was previously designed so that its range of frequencies includes the natural frequency of the primary structure. The primary structure design consists of a cantilever beam with the absorber attachment hardware, and the vibration absorber assembly consists of three rods and a stepper motor. The control algorithm uses a look-up table and a gradient search to optimize the effectiveness of the absorber for vibration reduction on the primary structure. The look-up table uses an equation, based on experimental data, to transform a given voltage input, directly proportional to the forcing frequency, into an output command necessary to adjust the natural frequency of the absorber. Once the input voltage reaches a steady state, the gradient search routine adjusts the natural frequency of the absorber to ensure the absorber is tuned to the optimal frequency that minimizes the primary structure vibration. The primary structure with the adaptive absorber offers significant reduction to the vibration amplitudes of the primary structure, as compared to both the primary structure with no absorber and the primary structure with a passive absorber, throughout the 45 Hz to 71 Hz and 73 Hz to 108 Hz range. The primary structure with no absorber has a 1^st mode natural frequency of 72 Hz and offers the lowest vibration amplitudes, as compared to both the primary structure with the adaptive absorber and the primary structure with a passive absorber, throughout the ranges of 30 Hz to 45 Hz and 108 Hz to 130 Hz. The primary structure with the passive absorber offers the lowest vibration amplitudes of the primary structure, as compared to both the primary structure with no absorber and the primary structure with the adaptive absorber, throughout the 71 Hz to 73 Hz range. / Master of Science

Research efforts pertaining to natural organic material (NOM) have focused primarily on the dissolved portion of NOM since it is the most prevalent fraction. Numerous procedures have been developed to separate dissolved organic material (DOM) into fractions but methods were not fully refined in the areas of quantitative analysis, DOM recovery, and DOM isolation. This research chemically and physically characterized DOM using synthetic resin adsorption and ultrafiltration, respectively. A 0.45 μm filter separated the NOM into particulate and nonparticulate fractions prior to characterization. The DOM of two natural waters were fractionated into six separate organic fractions (hydrophobic bases, acids, neutrals and hydrophilic bases, acids, neutrals). Apparent molecular weight distributions were performed on the two natural waters and six organic fractions via ultrafiltration. The effects of pH on coagulation removal efficiency were investigated on four of the organic fractions (acidic and neutral). A procedure was developed to investigate the synergistic/antagonistic effects of the hydrophobic acid fraction and the hydrophobic neutral fraction on each other during coagulation. Ultrafilters (30K and 100K nominal molecular weight cutoff) were utilized to analyze the phase-change behavior of DOM during coagulation. Results indicated the coagulation pH affected the removal of the organic acidic fractions but not the neutral fractions. A further study showed poorer removal of the hydrophobic neutral fraction resulting from the greater presence of the hydrophobic acid fraction in a solution composed of the two fractions and vice versa. At less than enhanced doses of both alum and ferric chloride there existed the presence of colloidal metal bound organic material. This colloidal fraction can be effectively removed by the addition of a nonionic polymer, providing a cost effective alternative to the higher coagulant doses often required to achieve enhanced coagulation of surface waters. / Master of Science

Social support plays a key role in the rehabilitation of acute and chronically ill people. Generally, if one receives some type of social support then he or she is more likely to improve their physical, emotional, and/or psychological well-being during the rehabilitative phase. The type and amount of social support the cardiac patient perceives may affect participation in cardiac rehabilitation. The purpose of this study was to 1) determine if there was a difference between the amount of social support perceived by men and women entering a phase II cardiac rehabilitation exercise program 2) to examine the relationship between social support and the first four weeks of rehabilitation compliance. A sample (n = 29) of twenty two men (63.1 y.o. ± 10.1) and seven women (70.4 y.o. ± 11.4) voluntarily completed the Medical Outcomes Study (MOS) Social Support Survey as they entered into the phase II programs. The sample population consisted of patients with one or more of the following characteristics: MI (76%), CABG (59%), PVD (21%), PTCA (28 %), diabetes (21 %), hypertension (48 %), and angina (41 %). Two sites were used in the study; one urban and one rural. Each program session consisted of 60 minutes of exercise which consisted of flexibility, cardiovascular, and strength conditioning routines. All sessions were monitored by exercise specialists and registered nurses. Classes met three times per week on Monday, Wednesday, and Friday. As patients entered the programs, they were administered the MOS Survey which consists of 19 questions that address four types of social support -- <i>tangible, affection, positive interaction, and emotional.</i> Each patient's attendance was recorded from initial entry to the end of four weeks. Data collection began in February 1995 and ended in May 1995. The results of the study demonstrated that there were no significant differences between men and women and their perception of social support at entry into the program. The mean total social support scores for men and women were 314.1 ± 85.2 and 307.1 ± 47.0 (p = 0.84), respectively out of a possible 400. There was no significant relationship between men and women and their compliance to the program (X² = 3.15, df 2; P = 0.21). In addition, there was no significant relationship between low, medium, and high compliers and their overall social support scores (p = 0.41). Results from these analyses should be viewed with caution as sample sizes were small. In conclusion, this study did not find that social support was associated with cardiac rehabilitation compliance. However, low entry rates into both programs and the extended length of the study resulted in very low sample sizes. Hence, the analyses may not have had sufficient statistical power to identity differences and make valid comparisons. / Master of Science

Architecture lies in the synthesis of place, purpose and process. Place and purpose are of course important however the focus of this thesis is process. This thesis is an inquiry into the opportunities and limitations inherent in typical building processes. I wish to more fully know essential concerns of building, concerns such as spanning, laying, draining and protecting. I wish to know, the filigree of steel trusses, the order of a masonry wall, and the memory of concrete. Knowledge of building process reveals opportunities to raise building into architecture. For the following design a pallet of building processes were assumed from typical high school construction, including: The leveling of the site. The pouring of a concrete floor. The laying of block walls veneered in brick. The placement of steel trusses. The following project is an attempt at bringing these typical conditions of construction alive, at revealing their qualities and ultimately raising them into architecture. / Master of Architecture