An instrumented oedometer was designed and constructed for the purpose of investigating at-rest and compaction-induced earth pressures in moist soils. The device has a split oedometer ring, and horizontal stresses are measured using load cells which support one half of the ring. Rapid cyclic loading was applied to compacted soil specimens, using a digital pressure regulator and a computer-based data acquisition system. The performance of the device was validated by performing tests on silicon rubber and Monterey sand. / Ph. D.

Two hypotheses were formulated to examine the additivity of perceived exertion in repetitive, symmetric, mid-sagittal lifting. "Additivity" has been defined as the means by which a whole-body rating of perceived exertion is composed of a weighted combination of component ratings of perceived exertion. The "task additivity" hypothesis asserts that a perceived exertion rating for the whole body in a floor-to-overhead lifting task can be modelled by the perceived exertion ratings of the component motions, i.e., floor-to-knuckle height lifting and knuckle height-to-overhead lifting. This is an inter-task (subtask) additivity paradigm. The "body-segment additivity" hypothesis asserts that the perceived exertion rating for the whole body in a floor-to-overhead lifting task can be modelled by a combination of the ratings of perceived effort from the arms, legs, torso, and central (cardio-respiratory) body functions. This is an intra-task (regional) additivity paradigm. / Master of Science

During a ten-stage compressor rig test conducted at Wright-Patterson AFB, several instances of compressor surge were observed. While surge is known to occur in high-speed multi-stage compressors, very little transient data pertaining to such events exists in the open literature, exclusive of engine data. In an attempt to make more data of this type available to researchers, surge data from the ten-stage compressor test is presented and analyzed in this thesis. Graphical presentation and data analysis techniques are employed in an effort to characterize the surge behavior of this compressor. Furthermore, the predictions of a computer-based transient compressor model are compared to the data for study. In the course of reviewing the data included in this thesis, certain abnormalities were noted in the overall behavior of this compressor. During testing, several researchers found that the speed boundary between surge and rotating stall occurred between 80% and 81 % corrected design rotor speeds. 1hls boundary did not change when the compressor discharge volume was increased or decreased. This seemed to contradict accepted theory, which predicts a shift in the surge/rotating stall boundary with discharge volume changes. An investigation into the possible causes of this phenomenon was conducted as part of this thesis. Several theories were explored, including the possibility of excess volume communicating with the compressor during instability. Although the excess volume theory could not be proven, it remains the most likely cause of the usual surge/rotating stall boundary behavior. / Master of Science

A pilot-scale system was constructed at the Martinsville Publicly Owned Treatment Works (POTW) in Martinsville, Virginia, to evaluate an anaerobic/aerobic treatment scheme for removal of color from textile dye waste waters mixed with municipal sewage. Treatments were evaluated with and without addition of a reducing agent (thiourea dioxide) after anaerobic treatment utilizing 6 and 12 hour anaerobic hydraulic retention times (HRT). Polymer treatment of the aerobic effluents and toxicity of the wastewaters to Ceriodaphnia dubia and Pimephales promelas were studied. In addition, the benefits of polymer treatment of anaerobic effluent, prior to aerobic treatment, were evaluated in a lab-scale system utilizing continuous flow biological reactors (CFBRs). Wastewater samples were collected throughout the treatment schemes and analyzed for: color, total organic carbon (TOC), 5-day biochemical oxygen demand (BODs), chemical oxygen demand (COD), total phosphorus, sulfide, sulfate, total Kjeldahl nitrogen (TKN), ammonia, nitrate, chloride and oxidation-reduction potential (ORP). Nearly 50% color removal was observed during anaerobic treatment with a 12 hour HRT, with a total system color removal, including subsequent aerobic treatment, of about 53%. / Master of Science

The objectives of this exploratory research were to 1) operationally define culture strength, 2) develop a procedure for measuring culture strength in organizations, 3) and demonstrate the culture strength measurement procedure in one or more organizations. I used the culture strength measurement procedure in two organizations-a large research organization at a major university and the headquarters organization of a regional provider of life insurance products and services. I used analogies from materials engineering and psychology to help conceptualize and operationally define culture strength. I studied the effectiveness of five culture strength measures (intensity, core values, cultural behavior, effects from external forces, and the gap between the existing and desired culture) to predict three criterion variables (employee commitment, job satisfaction, and group cohesion). I constructed my measurement instrument using mostly existing scales modified for my application. I developed a scale to measure the force effect relationship. I found work groups with stronger cultures had smaller gaps between their existing values and their desired values, had many people whose behavior reflected the desired values, had people whose behavior reflected many of the 53 values used in the survey instrument, had a small set of work group values held tightly by their people, and that small set of work group values closely mirrored the set of values held tightly by all members of the organization. I used a canonical correlation analysis for the culture strength measures at the individual level and rank order correlations for culture strength measures at the work group level. I found culture gaps and its factors (as determined through a factor analysis) were consistently good predictors of the criterion variables. Cultural behavior, a measure of the percentage of people whose behavior reflects a set of mostly positive values, was also a good predictor of the criterion variables. The effects scale was not an effective measure of culture strength in this research. / Ph. D.

Most of the lipid present in lactating mammary gland cytosol was associated with a high molecular weight aggregate isolated from cytosol by gel exclusion chromatography or by density gradient centrifugation. The major polypeptide constituent of this lipoprotein aggregate was the monomer of fatty acid synthase (FAS). The major milk lipid globule proteins, butyrophilin (8u) and xanthine oxidase (XO), as well as the small GTP-binding protein ARF, also were present. This lipoprotein complex was abundant in cytosol from lactating but not from involuting mammary glands. HPTLC analysis of lipids extracted from the low density FAS (LDFAS) complex demonstrated the presence of the five major milk phospholipids as well as triacylglycerols, cholesterol, unesterified fatty acids, and diacylglycerols. ³²P-labeled phospholipids present in cytosol could be transferred to microlipid droplets (MLD) and endoplasmic reticulum (ER), in vitro, and could be precipitated along with FAS, and other polypeptide constituents of the LDFAS complex. Complexed FAS could be separated from noncorrlplexed FAS by density gradient centrifugation, native PAGE, and gel exclusion chromatography. A large amount of phospholipid consistently was retained with the complexed form of FAS. These results suggest that FAS migrates to a low density fraction by virtue of its association to other proteins and lipids. FAS was found to be associated with ER, intracellular lipid droplets, and the milk lipid globule membrane (MLGM). A similar complex to LDFAS was isolated from ER from liver and mammary gland homogenates following incubation in buffer containing ATP. Polypeptide constituents of this complex had similar electrophoretic patterns to LDFAS, but behaved differently from LDFAS constituents when fractionated with the detergent TX-114. While most of the polypeptides in LDFAS partitioned equally into the detergent and aqueous phases, a constituent with an approximate molecular weight of 70 kDa was enriched in the detergent phase. For the ER-derived FAS complex, most of the polypeptides remained in the aqueous phase but the detergent phase also was enriched with a polypeptide similar in size to the LDFAS detergent enriched constituent. Western blot analysis failed to detect Bu in the ER-derived complex. However, protein disulfide isomerase (PDI) was detected in this complex as well as a polypeptide with approximate molecular weight 50 kDa that cross-reacted with PDI antibody. Extraction of lipids from this ER-derived complex demonstrated the presence of large quantities of unesterified fatty acids, with relatively low amounts of complex lipids. In studies using ¹²⁵I labeled LDFAS, labeled polypeptides were shown to associate with ER and intracellular lipid droplets and their dissociation was stimulated by ATP. Immunocytochemistry using antibody to rat liver FAS revealed distribution of FAS at localized regions of the cytoplasmic surface of rough endoplasmic reticulum and on surfaces of intracellular lipid droplets. Electron micrographs of the LDFAS complex showed a homogeneous morphology of granular, symmetrical particles ranging in size from 40 nm to 170 nm in diameter. These particles resembled low density lipoprotein (LDL) in morphology. From the available data, the following model was proposed for a possible involvement of FAS in lipid droplet secretion in the mammary gland. During active lipogenesis, FAS is targeted to ER membrane by association with a signal or targeting peptide(s) in the cytosol. The signal peptide then binds to selected regions of ER where signal receptors reside. Binding of FAS may initiate synthesis and accumulation of triacylglycerol between ER membrane bilayers. Upon the achievement of a "critical mass", the lipid core may be released into the cytoplasm in an ATP-dependent manner, surrounded by the membrane components that provided the hydrophobic pocket for lipid accumulation. Butyrophilin and the 70 kDa detergent-extractable constituent released from the ER and present in LDFAS are possible sources of such a function. Polypeptides from the cytosolic leaflet of the ER, and proteins peripherally associated with the leaflet then would comprise the polypeptide constituents of the lipid particle. / Ph. D.

Modeling growth dynamics of juvenile loblolly pine plantations can help to address important management decisions that have to be made in young stands. The present study addressed diameter and height prediction as well as crown development analysis as functions of independent variables such as site index, relative spacing and age for trees younger than ten years old. It was found that height prediction for trees one and two years old was a function of the products of the variables site index and age (or square root of age) and relative spacing and age (or square root of age). For trees three years old and older these were also the independent variables used to explain height prediction but in this case age (or square root of age) was another significant independent variable. In regard to diameter prediction it was observed that groundline diameter was a function of age for trees one and two years old; while this variable was also a function of site index and relative spacing for trees three, four and five years old. For trees older than five years old diameter at breast height was a function of age, site index and relative spacing. The analysis of crown development showed that for trees five years old and older variables like diameter at breast height, total height, age, site index and relative spacing were significant when crown ratio was the dependent variable. For trees younger than five years old, groundline diameter and the other same independent variables (i.e. total height, age, index and relative spacing) were again found significant when crown ratio was the dependent variable. / Ph. D.

This study analyzes the factors that influence promotion from assistant principal to principal and examines experiences that principals new to their position considered helpful to them from their assistant principalship. The participants in the study were new secondary principals in Virginia in 1992-93. A review of the literature revealed a need to examine promotion factors that are pivotal in selecting one principal candidate over another. The study method consisted of the development of a survey instrument based on the information found through the literature review, principal center criteria and results of an earlier independent study by the researcher questioning administrators regarding their work. The data collected by the survey was analyzed using descriptive statistical procedures. / Ed. D.

One of the most common tasks in many computer applications is the maintenance of a dictionary of words. The three most basic operations on the dictionary are find, insert, and delete. An important data structure that supports these operations is a hash table. On a hash table, a basic operation takes 𝑂(1) time in the average case and 𝑂(𝑛) time in the worst case, where n is the number of words in the dictionary. While an ordinary hash function maps the words in a dictionary to a hash table with collisions, a perfect hash function maps the words in a dictionary to a hash table with no collisions. Thus, perfect hashing is a special case of hashing, in which a find operation takes 𝑂(1) time in the worst case, and an insert or a delete operation takes 𝑂(1) time in the average case and 𝑂(𝑛) time in the worst case. This thesis addresses the following issues: Mapping, ordering and searching (MOS) is a successful algorithmic approach to finding perfect hash functions for static dictionaries. Previously, no analysis has been given for the running time of the MOS algorithm. In this thesis, a lower bound is proved on the tradeoff between the time required to find a perfect hash function and the space required to represent the perfect hash function . A new algorithm for static dictionaries called the musical chairs(MC) algorithm is developed that is based on ordering the hyperedges of a graph. It is found experimentally that the MC algorithm runs faster than the MOS algorithm in all cases for which the MC algorithm is capable of finding a perfect hash function. A new perfect hashing algorithm is developed for dynamic dictionaries. In this algorithm, an insert or a delete operation takes 𝑂(1) time in the average case, and a find operation takes 𝑂(1) time in the worst case. The algorithm is modeled using results from queueing theory . An ordering problem from graph theory, motivated by the hypergraph ordering problem in the Me algorithm, is proved to be NP-complete. / Ph. D.

The Parkinsonian-inducing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and close structural analogs are the only known cyclic tertiary amines with good monoamine oxidase substrate properties. In addition to its substrate properties, MPTP is a weak mechanism-based inactivator of monoamine oxidase-B (MAO-B). In an attempt to exploit the special interactions between this cyclic tertiary allylamine and MAO-B, studies were initiated to develop novel mechanism-based inactivators of this flavoenzyme. Analogs of MPTP bearing a variety of functional groups at either N or the C(4) position have been synthesized and their interactions with purified MAO-B have been characterized. The substituents selected included functionalities which were considered potential sources of enzyme generated electrophilic or radical intermediates that might alkylate and inactivate the enzyme. None of the C(4)-substituted compounds displayed significant enzyme inhibitor properties while the 4-phenyl-I-propargyl analog was a good mechanism-based inactivator of MAO-B but not MAO-A. The 4-phenyl-1-propyl derivative showed significant turnover with MAO-B suggesting that previous reports regarding the lack of substrate properties of MPTP analogs bearing N-substituents larger than methyl must be viewed with caution. The MAO-A and B generated dihydropyridinium metabolite derived from 1-methyl-4-phenoxy-1,2,3,6-tetrahydropyridine was | observed to undergo rapid hydrolytic cleavage to yield phenol and 1-methyl-2,3-dihydropyridone, a chromophoric species that could be monitored spectrophotometrically. This reaction sequence was exploited to probe the active site of MAO-A and MAO-B with a variety of C(4)-aryloxytetrahydropyridine analogs bearing groups of different steric bulk on the aryloxy moiety. Almost all of the compounds displayed good to excellent substrate properties with MAO-A and MAO-B. In contrast to previous claims, these results argue that the active sites of both MAO-A and MAO-B will accommodate tetrahydropyridine derivatives bearing bulky groups at C-4. Consequently other factors are likely to contribute to substrate selectivity. The results described in this thesis provide evidence that a variety of disubstituted tetrahydropyridine derivatives are good to excellent substrates for MAO-A and MAO-B. The new insights gained in terms of structure-activity relationships with the compounds studied here should set the stage for the design of other tetrahydropyridine analogs with therapeutic potential. The localization of MAO-A and MAO-B in specific cell types within the nervous system makes particularly attractive the possibility of designing tetrahydropyridine based prodrugs which will undergo bioactivation in selected cells in the nervous system resulting in the liberation of the pharmacologically active species. / Ph. D.