see document / Master of Science

A set of procedures for geographical information system analysis of wildlife-related problem areas associated with Virginia National Parks is presented. Analyses of both faunal and floral topics were made. The procedures presented address (1) evaluation of habitat resources available for reintroduction of bobcat (Lynx rufus); (2) mapping of avian species richness, (3) impacts of park boundary development on forest-interior bird species, and (4) identification of areas Suitable for threatened and endangered species (e.g., the small whorled pogonia, Isotria medeoloides). The GRASS GIS was used for the analyses. Inputs included data on elevation, slope, soils, landuse/landcover, roads, and hydrography. The procedures are built upon standard GIS techniques (e.g., overlays and “buffer” zones) and should be applicable to the mapping of habitat, species richness, and other information for various taxa in other resource areas. / Master of Science

The California poppy (Eschscholzia californica Cham.) has floral marketplace potential provided it can be produced as a well-proportioned potted plant. Its attractive floral display and tolerance of extreme heat and drought make it a good candidate for research aimed at introducing it as a new ornamental crop. The major objectives of this study were to document the apical meristem changes of California poppy during the transition to flowering, to determine the minimum number of inductive long-day (LD) cycles required for induction and initiation of flowering, and to examine the effects of exogenously applied gibberellin (GA₄₊₇) and auxin (NAA) on reproductive and vegetative development. Histological examination of apical meristems exposed to varying numbers of LD cycles revealed many changes commonly associated with the onset of flowering. There was an increase in RNA activity in the apical cells, an enhanced doming of the shoot apex, an increased elongation of primordia internodes, a disruption of the tunica-corpus organization, and the appearance of well-developed branch primordia. Eight to ten LD cycles was identified as the critical range required for successful flowering in California poppy plants when exposure to the inductive photoperiod was begun at the 8 to 12 true, expanded leaf stage. Exogeneous NAA was shown to have no significant effect on final reproductive status or vegetative development of California poppy. GA₄₊₇ application resulted in an enhanced shift toward reproductive development and an increase in stem elongation, but it had little effect on peduncle elongation. These results indicate that stem and peduncle elongation may be controlled by different mechanisms and warrant further research. The final chapter of the thesis concerning the design and evaluation of educational programs for the Virginia Tech Horticultural Gardens represents a departure from the major topic of study. This chapter is the result of the author's interest in, and the Garden's need for, an educational program suitable for the general public. This study can be considered the first step in the development of such an educational program. / Master of Science

M.S.

Gray leaf spot (GLS) of corn (Zea mays L.), caused by the fungus Cercospora zeaemaydis (CZM) (Tehon and Daniels) has increased in incidence and severity with increasing use of no-tillage and continuous corn practices. This disease can be yield limiting. Corn hybrids were evaluated under natural disease pressure for three years (1989, 90, and 91) at two locations (Montgomery and Wythe Co., VA). Yield losses ranged from 2127.4 kg/ha (Wythe Co., 1991) to 4242.2 kg/ha (Wythe Co., 1990). It was estimated that 77% of the variability in yield was due to GLS. Fungicides were evaluated for the control of GLS over three years on a susceptible hybrid, Pioneer Brand 3320. All fungicides, with the exception of mancozeb, provided significant control over nontreated check in all years. Benomyl, propiconazole and terbutrazole were the most effective fungicides. As much as 93% of the variablilty in yield was attributed to blighting. Reduction in blighting also increased the kernel weight. The toxin, cercosporin, produced by CZM was evaluated for its ability to elicit differential responses in corn germplasm by three methods, ie., vein inoculation, root, and shoot uptake. No consistant differential reponses were found with vein inoculation, but 31-day old plants were significantly more sensitive to the toxin than 21-day old plants, as measured by lesion width. Root and shoot uptake of the toxin by inbred germplasm produced lesions that resembled those produced by CZM in the field. Microscopic, yellow fluorescing crystals were found associated with necrotic tissue from toxin-treated inbreds. Significantly more injury occurred to toxin-treated inbreds exposed to light than to darkness. By chromatographic analysis, 407.1-1076.7 ng of toxin/g of tissue was recovered from leaf lesion extracts of plants exposed to light. Five inbreds (B73, H99, Va59, NC250a, and NC264) showed consistent and differential responses to the toxin. H99 and NC250a showed differential responses to the same concentration of toxin, thus suggesting that some germplasm are more sensitive to the toxin than others. Tests using the toxin as a means to identify resistant germplasm did not provide reliable predictions of germplasm response to CZM in the field. / Master of Science

This field study investigated the relationship among behavioral and perceptual measures of the Leader-Member Exchange (LMX) relationship and organizational outcome variables. The major purposes of this study were to determine: (1) the extent to which the dyad is the appropriate level of analysis for the examination of manager-subordinate relationships, (2) which objectively observed managerr behaviors are important in defining negotiating latitude, the most commonly used measure of LMX, and (3) whether these behaviors or traditional self-reports of negotiating latitude better predict organizational outcome variables. Two hundred ninety-two manager-subordinate dyads from 18 work groups in a manufacturing plant were observed by trained research assistants and completed questionnaires. Measures included observed manager behaviors defined by the Operant Supervisory Taxonomy and Index (OSTI), subordinates' absence rates, and managers' and subordinates' perceptions of subordinates' satisfaction (general satisfaction, satisfaction with supervisor, growth satisfaction, work satisfaction, coworker satisfaction), subordinate's intent to withdraw, and negotiating latitude (NL). Within and between analysis I (WABA I) indicated the manager-subordinate dyad as the appropriate level of analysis for NL, general satisfaction, satisfaction with supervisor, growth satisfaction, work satisfaction, coworker satisfaction, and turnover intent. WABA II revealed significant dyadic relationships between NL and all measures of satisfaction as well as turnover intent. Bivariate regression analysis revealed a significant relationship between negotiating latitude and absenteeism. Multiple regression analysis showed manager behaviors (i.e., antecedents) predicted negotiating latitude. However, multiple regression failed to reveal that manager behaviors predicted measures of satisfaction, turnover intent, or absenteeism. Finally, hierarchical regression revealed that manager behaviors (i.e., consequences) added to the predictive ability of negotiating latitude for general satisfaction. However, the addition of manager behaviors to negotiating latitude using hierarchical regression failed to produce a significant change in R-square for any other outcome variables. / Ph. D.

The purpose of this dissertation was to analyze theoretically and test empirically the impact of individual misperceptions about the costs and benefits of public activities on the size of the public sector. In chapters 2 and 3, the literature on misperceptions and deceptive practices in competitive markets and in the public sector was reviewed. It was demonstrated that because private and public goods possessed credence characteristics which cannot be evaluated even after a purchase, permanent misperceptions could exist about the marginal benefits of those goods. It was also argued that because of the rational ignorance of voters and the costs of information about marginal tax-costs, individual voter-taxpayers could be fooled permanently about their respective tax-prices of public goods and services, In comparison, such misperceptions of prices were considered improbable in the private sector because of the low information costs involved. In chapter 4, the effect of permanent misperceptions of marginal costs and benefits on the level of public activities was derived by using the median voter model. For example, it was demonstrated that the permanent underestimation of marginal costs could lead to a contraction rather than an expansion of the public sector while the simultaneous underestimation of costs and benefits could promote greater public expenditures than if costs alone were misperceived. In chapter 5, the incentives of government in promulgating permanent misperceptions by voter-taxpayers were studied. It was argued that in most circumstances, government would benefit by letting taxpayers underestimate their tax costs and overestimate their benefits permanently. Finally, chapter 6 reviewed the empirical evidence related to the existence of fiscal misperceptions. It was concluded that while numerous investigations demonstrated that taxpayers were unaware of a variety of taxes, there were little clues suggesting that they will consistently underestimate their tax burden under particular financing institutions, Additional empirical tests presented in this study further suggested that the level of state expenditures in 1978 was relatively independent of the financing methods used by governments. The share of public debt in state revenues was the only variable found to have a statistically significant correlation with public expenditures. / Ph. D.

Two mathematical models are applied to the study of a flight performance problem for an air-superiority fighter aircraft. The first model considers the body axes angular rates as control variables and is accordingly referred to as the body rate model. The second model is a rigid body model featuring rotational dynamics governed by the primary control surface deflections. The body rate model is intermediate between a point-mass model and rigid body model and accordingly, useful for preliminary design applications. Comparisons between the two models are made to determine the utility of each when applied to a particular flight problem. The integral flight performance problem combines notions of roll and pitch agility in a roll reversal maneuver. The flight problem is formulated as an optimal control problem for each of the models. Parameter variations in the initial flight condition specified by the load factor, and in the available roll and pitch control powers were studied and used to compare the models. The results indicate deficiencies in the body rate model as an accurate predictor of agile aircraft characteristics. / Master of Science

An experimental system was built to test the effect of various process parameters on the performance of the Modified Dry Limestone Process (MDLP) for flue gas desulfurization. Two types of limestone, one calcitic and one dolomitic, were used. These materials were characterized by ICP analysis, X-ray diffraction, optical microscopy, SEM, and electron microprobe before and after reaction. Performance was judged on the basis of the formation of a friable gypsum reaction product and the maintenance of a pH of about 4.84 or higher in water through which the exit gases were bubbled. Two primary and one secondary parameter were identified as the most important for optimum performance of the MDLP. The two primary parameters were temperature and water content. A temperature of 68°-70°C promoted reaction, while no reaction occurred at 31°C. The solubility of SO₂ in water was the controlling factor for water content. A maximum ratio of about 3.4 g SO₂/100 g water at 69°C was necessary. The secondary parameter was the type of limestone used. A dolomitic limestone with a reasonable amount of Fe performed better than either marble or a calcitic limestone, both low in Fe. A reasonable amount of Fe and an extensive pore structure seem to be the most important factors in limestone SO₂ absorption performance. / Master of Science

M.S.