In our previous studies, uncross-linked large diameter cellulose beads were optimized for solids content, bead size, pressure-flow limits, molecular accessibility and performance as an immunosorbent. Here, anion exchange (DEAE) cellulose beads were derivatized by two different procedures (defined as A and B) and the changes in bead morphology were correlated with transport and sorption kinetics. The kinetic characteristics clearly defined a minimum of two different types of protein binding site architecture. DEAE cellulose beads exhibited molecular exclusion of BSA near the edge of the bead in contrast to greater permeability seen in underivatized beads. Thus, accessible BSA binding sites are present only on the surface of the derivatized beads. DEAE cellulose beads derivatized by procedure B gave higher density of DEAE ligand as compared to beads derivatized by procedure A, as well as higher static and dynamic capacity for BSA. Even though DEAE cellulose beads (DP 2070, 450 μm diameter derivatized by procedure B) have lower small ion capacity than DEAE cross-linked agarose beads, as well as 1/4 the surface area, they exhibit equivalent binding capacity for BSA per volume of support. Thus, DEAE cellulose beads possess more sites per surface area as well as have lower ligand density per BSA site. Furthermore, BSA adsorption sites on DEAE cellulose beads derivatized by procedure B exhibit slow binding kinetics as compared to those derivatized by procedure A and also compared to DEAE crosslinked agarose beads. Thus, the rate limiting step for the adsorption of BSA on DEAE cellulose beads was not diffusion as suggested by the large diameter of the bead. Feasibility studies were performed for process scale applications to fixed and expanded bed anion exchange purification. The large diameter DEAE cellulose beads of this study maybe useful for process scale anion exchange as evident from purification of immunoglobulins from hybridoma cell culture in fixed bed. The balance of large diameter and density of these DEAE cellulose beads enable stable expanded bed purification of proteins such as recombinant human protein C from transgenic porcine whey. / Ph. D.

Phosphorylase kinase (EC 2.7.1.38) is a key enzyme involved in the regulation of the glycogenolysis pathway. It catalyzes the Ca²⁺-dependent phosphorylation and activation of the enzyme glycogen phosphorylase to make the active form glycogen phosphorylase. Phosphorylase kinase is composed of 4 subunits with a stoichiometry of (αβγδ)₄. The γ subunit is the catalytic subunit. The regulatory domain (residues 277-387) of γ contains a sequence resembling the sites phosphorylated in known γ substrates with the exception that a valine₃₃₂ occurs at the analogous position of the phosphorylated serine or threonine residue. / Ph. D.

The effect of specimen size on the uniaxial tensile stress/strain response of sublaminatelevel scaled composite specimens, and the four point flexure load/deflection response of ply- and sublaminate-level scaled composite specimens was investigated. Three laminates were studied in the tensile program, namely [+30/-30/90₂]_ns, [+45/-45/0/90}_ns and [90/0/90/0|_ns, where n = 1, 2, 3, 4. Two material systems were used, namely AS4/3502 graphite/epoxy and APC-2 graphite/PEEK, to investigate the relative effect of resin toughness. Three laminates were also studied in the flexure program, The baseline lay-ups were (±45/0/90}_2ns, [0/90/0/90J_2ns and [±45/±45J_2ns, where n = 1, 2, 4. Ply- and sublaminate-level scaling were used to increase specimen thickness. All flexure specimens were of AS4/3502 graphite/epoxy. Enhanced X-ray radiography and edge photomicroscopy were used to examine damage development in specimens loaded to various fractions of their ultimate stress. This nondestructive examination was coupled with observations of critical events in the stress/strain response to try to correlate scaling effects with the damage development in the specimens. Analytical and numerical methods were employed in order to understand the stresses driving certain damage modes observed. 2-D and 3-D finite element models were used to find delamination stresses in an undamaged laminate, and an approximate clasticity approach was used to find stresses duc to cracks in the 90° plies. It was found that the tensile strength of the [+30/-30/90₂]_ns and [+45/-45/0/90}_ns laminates gencrally increased as n increased. This effect was more pronounced for the matrixdominated [+30/-30/90₂]_ns. Both the [+30/-30/90₂]_ns and the quasi-isotropic [+45/-45/0/90}_ns laminates seemed to be approaching a maximum strength, beyond which the strength scaling either stops, or is reversed. As # increased from 1 to 4, these two laminates exhibited a delay in the onset of certain damage mechanisms, such as delamination and transverse matrix cracking. The [90/0/90/0|_ns laminates showed no tensile strcss/strain response scaling effects, although the stress at which first ply failure occurred was found to increase as 7 increased. (±45/0/90}_2ns and [±45/±45J_2ns flexure specimens showed no strength scaling cffects when sublaminate-level scaling was uscd, but significant decreases in s{rength were found when specimen size was increased using ply-level scaling. [0/90/0/90J_2ns specimens showed no global load/deflection scaling effects. / Ph. D.

Polyimides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropane (BDAF) and pyromellitic dianhydride (PMDA) displayed a glass transition temperature (Tg) at 306°C and a melting point (Tm) near 470°C as measured by differential scanning calorimetry (DSC) with a heating rate of 10°C/min. The degree of crystallinity increased with decreasing molecular weight. The incorporation of 20 mole percent of the comonomer, hexafluoroisopropylidene-2,2-bisphthalic acid anhydride (6FDA), gave a Tm of 440°C that appeared to be stable 20°C above the melt. A fluorinated diamine, 1,1-bis[4-(4-aminophenoxy) phenyl]-1-phenyl-2,2,2-trifluoroethane (SFEDAM), was synthesized in 80% yield from trifluoroacetophenone with a melting point of 169-170°C. The 3FEDAM-PMDA polyimide controlled to 30,000 g/mol with phthalic anhydride exhibited by DSC a Tg of 308°C and a Tm of 476°C. Similar to the BDAF based copolymer, the 3FEDAM-20%6FDA/80%PMDA-PA polyimide had a Tg of 286°C and a Tm of 440°C which appeared to show short term thermal stability above the Tm. Three 1,4-bis(4-aminophenoxy)benzene (TPEQ) homopolyimides were synthesized with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenylcarboxylic dianhydride (BPDA), and 4,4'-oxydiphthalic anhydride (ODPA). The Tg values were 255°C, 251°C, and 239°C for the TPEQ-BPDA-PA, TPEQ-BTDA-PA, and TPEQ-ODPA-PA polyimides, respectively. The TPEQ-ODPA-PA polyimide displayed the lowest Tm of 411°C. A series of TPEQ-ODPA polyimides of different molecular weights were synthesized using the Carother's equation and the monofunctional reagent, phthalic anhydride. The Tg values ranged from 214°C to 239°C for the 7.5K to the 30K polyimides. All the TPEQ-ODPA polyimides displayed an endotherm on the first heat of the DSC analysis. However, the 7.5K, 10K, and 15K polyimide also recrystallized upon heating. Polyimide powders were directly synthesized via preparation of the poly(amic acid) followed by cyclodehydration by solution imidization. One requirement is the polyimide must be crystalline so that as the polyimide is formed it will crystallize and precipitate from solution as small particles in the range of 2-16 pm. The particle size may be controlled by the concentration of the solution, temperature, and drying process. / Ph. D.

Increasing individual's physical activity in our country is a primary health promotion and disease prevention concern. Yet, much of the population remains sedentary and thus, at increased risk for several diseases such as hypertension, coronary heart disease and hyperlipidemia. Unfortunately, programs promoting physical activity have had limited success in increasing activity and even less success in maintaining a program over time. The "Exercise for Everyone" program was designed to assess the effectiveness of behavior change strategies developed for maintenance on physical activity using individuals recruited through a community setting. Any type of moderate physical activity (e.g., vacuuming, gardening, walking, swimming etc.) was considered appropriate and encouraged. The researcher used the following behavior change strategies: telephone prompting, and self-control strategies: self-monitoring, participant set goals, self-reinforcement, self feedback and problem-solving strategies. In this study, frequency of contact was varied from no contact, to once per every week, to once per every third week over 16 weeks and faded in the last four weeks. All participants were asked to self-monitor their physical activity, and all participants received either an information only class or a self-control strategies class. Survival analysis using five months of data points and using the criteria of first week of activity missed equaled "death" indicated an effect of greater adherence for individuals participating in a strategies class versus an information only class (46% vs. 14%), but not for the effect of frequency of contact (no contact, 33%; low contact, 31 %; high contact, 30% ) over all 18 weeks of the program. The results suggest the efficacy of a low cost class promoting self-control strategies for behavior change for adherence to an activity program and potentially for other health related behaviors. / Ph. D.

A phenological model of gypsy moth egg development is proposed that distinguishes three phases of egg development, prediapause, diapause and postdiapause. A technique of measuring respiration rates of individual eggs was developed and respiration rate was used as a physiological variable to distinguish the phases. The pattern of respiration rate provided strong evidence in support of three distinct developmental phases. Respiration rate developed embryos declined sharply as prediapause was entered and rose sharply when diapause was completed. When the effect of age on respiration rate was removed, temperature had a uniform effect on respiration rate throughout the egg stage. A 10°C decrease in temperature caused an approximate 0.4 fold decrease in respiration rate, indicating that eggs in diapause are as equally responsive to temperature as egg in a nondiapause phase. Developmental rate in prediapause was strongly temperature-dependent, and the relationship was described by a non-linear function. Prediapause duration was approximately 13 days at 31°C. The depletion of stored triglycerides was strongly linked to the completion of prediapause. Developmental rate in postdiapause was found to be temperature- and age-dependent. Developmental response to temperature was relatively weak and linear at the onset of postdiapause. As postdiapause advanced, the response became stronger and non-linear. The temperature- and age-dependent developmental response was fully described by the temperature-dependent developmental response at the onset of postdiapause, and by a temperature-dependent rate change parameter. / Ph. D.

This thesis estimates the economic impacts of the Virginia-Maryland Regional College of Veterinary Medicine on the Commonwealth of Virginia. Two types of economic impacts were measured. First, the short term impacts were assessed, using the input-output model for the Commonwealth of Virginia. Operating expenditures of the college were entered into the model as a change in final demand and the multiplier effects of these expenditures were measured. Second, long run benefits of the College's research and extension program were estimated using the economic surplus approach. A sample of the college's research and extension projects was selected, and aggregate benefits for the college were evaluated. The study found substantial impacts of the college on the Commonwealth. The total impacts of the college on total output, income, Gross Domestic Product and employment on an annual are $44 million, $26 million, $28 million and 707 respectively. The sample of research projects evaluated, generated net benefits of $12 million. The aggregate benefits of the college are estimated at $48 million. The benefit-cost ratio for the college's research is 3.1. / Master of Science

The purpose of the present study was to provide evidence of discriminant validity for the aberrant self-promotion construct proposed by Gustafson and Ritzer (1994a). The study attempted to differentiate the aberrant self-promotion construct from the Machiavellianism construct proposed by Christie (1970a). The aberrant self-promoter (ASP) has been conceptualized as exhibiting high self-esteem, low social desirability, and a high degree of antisocial behavior. In contrast, the Machiavellian has been conceptualized as an individual who is coldly rational in determining his or her actions and who is adept at engaging in manipulation to achieve a desired end. It was proposed in the present study that although both the ASP and the Machiavellian may be characterized by high narcissism, high self-esteem, and low social desirability, the Machiavellian does not exhibit the antisocial behavior that is a key component of the ASP pattern. The proposed differentiation, based on 28 undergraduate ASPs and 19 undergraduate Machiavellians, involved a structured interview and a prisoner's dilemma game. The results from the interview showed that the ASPs scored significantly higher on the total score, as well as on the subscore for a narcissism-related factor and on the subscore for an antisocial behavior factor. The prisoner's dilemma results, however, revealed no significant differences between the ASPs and Machs. Discussion focused on the insufficient salience of the prisoner's dilemma experimental situation and on the research and organizational implications of the ASP/Machiavellian differentiation supported by the interview. / Master of Science

Pathologic processes and surgical manipulations of the spinal column may result in alterations of the biomechanical properties of the spine through increases or decreases in the range of motion or stability of the spine. A decrease in range of motion between two adjacent vertebrae subsequent to arthrodesis or ankylosis appears, clinically, to be well tolerated without significant alterations to the functions of the spine; however, a decrease in spinal column stability as a result of pathologic changes or surgical alterations can result in catastrophic spinal cord injury. In order to determine the effect of various surgical procedures and trauma on the spinal column, in vitro biomechanical studies may be employed using a servohydraulic testing apparatus and cadaver vertebral motion units. The T₁₃ - L₁ vertebral motion units of 48 mix breed dogs were dissected free of surrounding musculature and prepared for biomechanical testing by mounting with cross pins and polymethylmethacrylate. Specimens were surgically altered by facetectomy, lateral fenestration, diskectomy, and combinations of these procedures. Specimens were subjected to lateral bending at a rate of 2.5 cm per minute to failure in a swing arm bending jig designed to simulate four point bending. The slopes of bending moment vs. angular displacement curves were compared and significance determined by the method of least squares. A statistical difference (p < 0.05) was found between the stiffness of all diskectomy groups when compared to any other group. Unilateral and bilateral facetectomies, and fenestration induced a non-significant decrease in stiffness in comparison to control specimens. This data may be combined with that of previous testing of the canine thoracolumbar spine in flexion-extension and rotation to determine the clinical effects of surgical manipulations and trauma on spinal stability. These results suggest that fenestrations and facetectomies do not appear to increase the risk of injury to the canine thoracolumbar spinal cord during lateral bending in the in vitro model; however, thoracolumbar spinal fractures involving the vertebral body as represented by the diskectomy in vitro model may significantly destabilize the spine in lateral bending. / Master of Science

In this research, I attempted to show that increasing a person's computer self-efficacy is a viable route to making that person more likely to use a computer tool when given the opportunity to do so. I also show the strong link between a person's computer self-efficacy and intentions to use a computer. Computer self-efficacy is a person's belief about his or her ability to successfully use a computer. Subjects in this field experiment were 193 students in eight introductory computer classes at two colleges. I attempted to increase their computer self-efficacy through their participation in a self-efficacy-increasing strategy that used goal-setting, self-reinforcement, and feedback. Half of the subjects randomly received this strategy, and half received a placebo strategy, which was not expected to have any influence on the subjects' computer self-efficacy. Due to the subjects’ insufficient use of the strategies, I was unable to increase the computer self-efficacy of the subjects through this strategy. Although the subjects’ computer self-efficacy was not increased, I was still able to see the effect of computer self-efficacy on a person's intentions to use a computer. Of all the variables tested in this study, computer self-efficacy was the best predictor of intentions to use a computer—better than computer experience, computer ownership, academic major (computer-related vs. not computer-related), instrumentality beliefs about computers, and others. This finding showed that computer self-efficacy is a construct that people should pay attention to, particularly people who design computer tools, those who choose which tools to use, and those who train others on new computer tools. These people should particularly understand the needs of users with low computer self-efficacy and how to best meet those needs. Additionally, I tried to find out why the subjects did not participate in the use of the strategy. It appears that the main problem in my implementation of the self-efficacy strategy was not providing the subjects the proper amount of time, encouragement, and incentive for learning and practicing the strategy. My results also showed that those who used the strategy had higher computer self-efficacy than those who didn't use the strategy; that is, those who could benefit most from the self-efficacy strategy (those with low computer self-efficacy) were less likely to use it. This finding underscores the importance of providing a supportive environment for people to learn and practice the strategy, so those with low computer self-efficacy will be able to use the strategy successfully, rather than avoid the strategy before they even get a chance to learn or use it. / Master of Science