Tangential slot injection of supersonic air (M_j = 1.70) into a supersonic air freestream (M₁ = 2.93) was investigated. The model used had a slot height of 1.27 cm, which was also approximately the boundary layer thickness in the primary stream, and a thin splitter plate with a thickness of 0.052 cm. Computer controlled measurement systems were used at four streamwise stations, (x/a) = 0.25, 4, 10, 20, to determine cone static pressure, pitot pressure, and stagnation temperature. From this information profiles of M, U, and ρ̅ were also generated. Spark Schlieren and Nano-Shadowgraph pictures were taken of the flowfield. The results showed excellent repeatability and documented the development of the injected flow to beyond the region where the outer shear layer and wall boundary layer had merged. The effect of a weak shock interaction upon the shear layer was also investigated. An oblique shock, generated on the upper wall with a wedge, impinged on the shear layer. The shock wave had a nominal pressure ratio of 1.82, which did not result in separation of the wall boundary layer. The profile distortion caused by this shock/viscous layer interaction was documented. / M.S.

Project objectives were to develop an improved plating medium to achieve reproducible colony counts and accurate quantification for growth or survival of Spirillum volutans; and to develop an improved method for selection of S. volutans from nature. Growth enhancement studies began with casein hydrolysate-succinate-salts medium (CHSS). Casein hydrolysate concentration, type of casein hydrolysate, pH, and phosphate concentration optima were determined. Growth of S. volutans doubled after 24 h with the addition of potassium phosphate buffer (1 mM final concentration) to CHSS medium (CHSS-P). Addition of supplements to CHSS-P medium, and modified Bordetella and Brucella media failed to increase the cell yields of S. volutans. Punctiform colonies did form in CHSS-P medium (0.7% agar) pour-plates, yet at a recovery rate much lower than reported by Padgett et at. (1982) for surface growth on spread plates. The role of amino compounds as possible growth factors was investigated. Thin-layer chromatography, gas chromatography, and amino acid analysis were employed to identify those amino compounds (if any) that decreased or disappeared in the medium after 48 h of growth. None could be found. Numbers of viable cells were not greatly increased, however, viability was prolonged by growing S. volutans in dialysis sacs suspended in CHSS-P medium. The tolerances of S. volutans to several antimicrobial compounds were determined. Attempts at using hay infusion, Pringsheim, and CHSS-P media supplemented with various compounds as selective agents did not result in predominance of S. volutans. / M.S.

There is considerable agreement that a basketball team enjoys some type of advantage on the team's home court. This study tried to determine whether that advantage was evident in the team's statistics, and whether that advantage was significant over time. The experimental design consisted of t-tests performed on nine different statistical categories, comparing home and away performances. Those statistics were gathered from 43 home and 43 away Virginia Tech regular season Metro Conference men's basketball contests from 1979 through 1987. Results from the testing indicated that there were significantly more points scored at home than on the road. Also, testing showed that Virginia Tech had a significantly higher winning percentage at home than it did on the road. While testing revealed that there were no significant differences in the other seven categories studied, it was concluded that slightly better performances across several categories may cause greater success at home. Continued research on the home court advantage theory is suggested. / M.S.

Erwinia carotovora subsp. Carotovora (Ecc) and Erwinia carotovora subsp. Atroseptica (Eca) are plant pathogenic bacteria that cause soft rot disease of many plant species and blackleg disease of potatoes, respectively. Ecc and Eca attack plants by means of a group of extracellular plant tissue-degrading enzymes. which rapidly breaks down the pectic polymers that form a structurally important part of the plant cell wall, is considered central to soft rot pathogenesis. In this work, I isolated and studied the genes encoding this enzyme from Ecc and Eca. A clone library of Ecc strain EC14 was constructed using cosmid PLAFR3. This library contains 2,200 clones with an average insert size of 27 kilobases of DNA and included a proteolytic clone, five cellulolytic clones, and ten pectolytic clones. The proteolytic clone was used to complement a Tn5-induced protease mutant of Ecc; the complemented mutant was restored to near-wild type phenotype. Six of the pectolytic clones hybridized to a probe from a. previously isolated extracellular endo-pectate-pectate lyase gene from Ecc; one pectolytic clone had homology to a previously isolated clone encoding endo-polygalacturonase: three clones showed no relationship to either of the previously characterized Ecc pectolytic enzyme genes. A clone encoding the major endo-pectate lyase gene from Ecc was chosen for subcloning and further study. I used the plasmid vector pBR322 to construct a clone bank of Eca strain SRB; of the 1700 clones screened, five were pectolytic. Two of the Eca pectolytic. clones had homology to the Ecc endo-pectate lyase gene; upon examination, they proved to contain the same insert in opposite orientations. The Ecc endo-pectate lyase had a pI of 9. 5 and a molecular weight of 33,000; the analogous Eca endo-pectate lyase had a pI of 9.2 and a molecular weight of 31,000. Both enzymes required a divalent cation for activity (preferring Ca2+ over Mg2+ over Mn²⁺. The restriction endonuclease maps of the two clones did not have any tested sites in common. These differences suggest that although these two genes may have originated from a common ancestral gene, considerable divergence has taken place. I analyzed the fine structure of the Ecc endo-pectate lyase gene by DNA sequencing. The coding region of the gene is preceded by E. coli-type -10 and -35 sequences and encodes an unmodified protein of 281 amine acids. A typical secretion signal peptide is not present. / Ph. D.

Temperament of 4-month-old infants of diabetic (n=l6) and nondiabetic (n=l8) mothers did not differ reliably in terms of maternal ratings on the Infant Behavior Questionnaire (IBQ) (Rothbart, 1981). Item analysis indicated that scales on a reduced version of the IBQ maintained high internal reliability. Discrete behaviors, adapted from the Infant Behavior Record (Bayley, 1969), and conceptually related to each scale of the IBQ, were observed by mothers and by a trained observer during the infants' well-child examinations. Group differences for activity level and duration of orienting were obtained by the trained observer. These differences were similar in pattern to those found by Yogman, Cole, Als, & Lester (1982) on newborn infants of diabetic mothers. Mothers' observations were reliably correlated with those of the trained observer on the following scales: (a) smiling and laughter, (b) fear, (c) distress to limitations, (d) soothability, and (e) duration of orienting. Mothers' observations were not reliably correlated with those of the observer on (f) activity level. The behavioral items were not significantly correlated with their respective scale on the IBQ. With subjects from both groups combined, neither gestational age nor ponderal index was related to temperament ratings or to discrete behaviors. Results failed to support the hypothesis that diabetic-related biobehavioral vulnerabilities and psychoendocrine mechanisms mediated temperament in 4-month-old infants. However, differences in discrete behaviors were present. Further studies are needed to determine whether differences of discrete behaviors affect later development. / M.S.

The basic resource of all solar systems is the sun, and a knowledge of the quantity of the energy available is of prime importance. Although the solar radiation outside the atmosphere is known and almost constant, various climatic factors cause wide variations in its value on the earth's surface. In addition, the relative position of the sun with respect to local points of interest will allow surfaces with different orientations and tracking ability to receive different quantities of solar energy. This research focuses on the effect of cloud cover on the solar radiation received on the earth's surface and presents computer models that calculate its value for the best system configuration. Then a complete assessment of the electrical output of such a system is given. With this purpose in mind, two solar resource evaluation models have been developed; the first method is based on a direct statistical approach correlating clear sky total daily radiation with measured daily insolation. This approach has been applied to a few selected sites and offers the procedure for extending the same coefficients to other sites with similar weather patterns. This model has been tested for six sites in Bangladesh . These sites are located around a "reference" site . The predictions made have shown to be quite accurate. The second model uses an analytical approach that combines clear sky methods with "correction" factors which are based on long term recorded solar ra- diation. In addition, this model has been enhanced by an algorithm that selects the optimal surface orientation that maximizes solar output. Finally, the hourly electrical output of the photovoltaic system is calculated after accounting for the various losses. This is presented as part of a complete solar energy evaluation model. / M.S.

Fear of crime is as much a reality as crime itself. Our reactions to the problem of crime may influence or interfere with our day-to-day activities. Yet not everyone is a victim of crime, nor does everyone perceive crime as being a serious problem. The author tests hypotheses about the relationships between the fear of crime and, (1) prior victimization, (2) perceived seriousness of crimes and (3) size of the community (population size); suggesting that all of these relationships will be positive--the higher the score for these three variables the higher the score for fear. Also, it was hypothesized that these relationships would be greater (a) for women than for men, and (b) for personal crimes than for property crimes.The survey was sent to a sample of registered motor vehicle owners in the state of Virginia; a sample of 952 was used in this study. All of the relationships were positive. Only two of the sub-hypotheses were supported: that the relationship between perceived seriousness and fear of crime was greater for women than for men, and that the relationship between population size and fear of crime was greater for women than for men. Implications of the results and the limitations of the study are discussed. Suggestions are made for future research. / M.S.

Although leaf movements have been documented for over a century, there are few studies focused on the adaptive significance of leaf movements, especially with experiments under controlled conditions. The major objective in this study is to determine the ecological significance of leaf movements in Rhododendron maximum, which is a subcanopy, evergreen species distributed in seasonally cold environments. Leaf movements could be necessary for maintaining a favorable energy balance and/or avoiding photoinhibition and photooxidation. A series of leaf manipulation treatments were established to verify these potential explanations. These leaf treatments were designed to separate the influence of leaf curling and leaf angle on leaf energy budget, gas-exchange characteristics, chlorophyll contents and leaf longevity. Leaf movements were found to have a significant influence on leaf physiology and longevity of R. maximum. Without changes in leaf angle, chlorophyll contents decreased, and permanent photoinhibition occurred due to excess irradiance absorption in the winter. Leaf angle also influenced leaf temperature although the changes in leaf temperature were within the physiological tolerances of R. maximum leaves. Leaf curing had little or no effect on the parameters measured in the study. / M.S.

The scurfy scales in the genus Chionaspis comprise a unique taxon among the armored scale insect genera in North America. The taxonomic reviews of the species belonging to the genus by Cooley (1899) and Ferris (1937, 1942) are far outdated. The present research is a comprehensive review of all the species in this genus in North America, with special emphasis on polymorphism associated with feeding sites which has been discovered in some species. Seventeen species have been redescribed and illustrated in detail, each with a discussion of their morphological affinities and relationships. Their host habits and zoogeography are summarized. The five species having typical bark and leaf forms, as well as intermediate forms, are discussed in more detail. A separate chapter deals with polymorphism, including a historical literature review of the subject. A hypothesis is given on the modes of transfer from the bark form to the leaf form and vice versa, that results in different morphs in first or second generations. Two keys were prepared: one for the genera related to Chionaspis and another for the determination of the species of this genus in North America. The three species that have been recently redescribed, C. americana and C. kosztarabi and C. nyssae are also discussed, and the most important morphological characters and the plates prepared by the original authors for each of these three species are given in order to better utilize the key to the species in North America. As a direct result of this research, two new species have been discovered: Chionaspis gilli Liu and Kosztarab, and C. hamoni Liu and Kosztarab. In addition new morphs were found for C. platani and C. wistariae. This thesis also includes many new distribution and host records for several species. The phylogenetic relationship of all the species in this study has been discussed, and as a result of the Ward's Minimum Variance Cluster Analysis (1985 version, SAS), a dendrogram has been provided based on 23 numerical characters. / Master of Science

An accurate knowledge of turbine blade surface temperature is desired in order to obtain maximum performance from turbine engines. A limited spectrum radiation pyrometer can be used for blade temperature measurement. A model is presented which predicts the output signal from the detector unit of a pyrometer in a turbine engine application. Six inputs are required for the model. The inputs are the turbine blade geometry, location of the pyrometer with respect to the blades being viewed, focusing parameters of the pyrometer, type of detector, transmission curve of the optical system, and an estimate of the blade surface temperature. The model uses Fortran 77 and IBM CADAM to create a three dimensional representation of the pyrometer path across the blades along with the intercepted target spots. Once the target spot areas are determined, the photocurrent output signal of the detector is predicted as a function of percent blade chord and time. Results are shown for different detectors and temperature distributions. Experimental data is also included, and a comparison is made between the data and the model. Any of the model input parameters can be varied so that different pyrometer schemes can be evaluated at either the initial design phase or after installation. / Master of Science