Relationships between nontaxonomic aufwuchs community structure and functions were examined over a variety of environmental or physiological conditions in model streams to ascertain any direct relationships or covariance between indices of structure (dry weight, ash free dry weight, adenosine triphosphate and chlorophyll a) and function (primary productivity and assimilatory sulfate reduction). In eleven experiments, individual streams were treated with potential"enrichments" of sucrose, dextrose, ammonium nitrate, potassium dihydrogen phosphate, and toxicants including copper sulfate, potassium dichromate and chlorine, in order to elicit responses by the aufwuchs communities that accumulated on artificial substrates. The carbon-14 method was adapted and refined using a chamber for measurements of primary productivity in lotic systems. Assimilatory (sulfur-35) sulfate reduction was investigated as a method for estimating net microbial production rates. The ability of indices or ratios of structural and functional values to reduce variability and identify perturbed model streams relative to untreated streams was evaluated. In laboratory studies, assimilatory sulfate reduction closely followed growth rates in batch cultures of algae (Stigeoclonium sp., Navicula pelliculosa and Oscillatoria tenuis), bacteria (Pseudomonas flurescens, Enterobacter aerogenes and Bacillus subtilis) and fungi (Penicillium clavigerum, Mucor hiemalis and Coprinus patouillardii). Linear uptake kinetics of sulfur-35 sulfate during a six hour incubation period indicated that the process was active or energy mediated. Patterns of algal sulfate assimilation closely paralleled those for primary productivity. Bacterial and fungal sulfate assimilation rates were generally lower in the light than in the dark although the differences were not statistically significant. Observed rates of assimilatory sulfate reduction by cultures of algae, bacteria and fungi were affected by concentrations of organic carbon (glucose) in the media; at concentrations of glucose greater than 5 mg l⁻¹, dark sulfate uptake by algae was 77-98% of light uptake rates, and at glucose concentrations greater than 50 mg l⁻¹, bacterial and fungal sulfate assimilation rates did not increase proportionately with increasing glucose concentrations. The concentration of organic sulfur as as cysteine and methionine, that caused a decrease in the rates of sulfate assimilation, was between 10 and 100 S l⁻¹ for both the cultures and mixed populations in microcosms. No extracellular sulfur-containing products were found to be excreted by mixed populations in microcosms, and no"luxury" consumption of sulfur was observed. The use of assimilatory sulfate reduction rates to estimate net microbial productivity in aerobic systems was supported by the results from investigations with the cultures and microcosms. A reduction in accumulated matter (as indicated by dry weight, ash-free dry weight and ATP) and chlorophyll a on artificial substrates occurred in toxicant (copper, dichromate and chlorine) treated streams. Photosynthesis (carbon fixation) was most sensitive to the copper treatment and assimilatory sulfate reduction was affected most often by dichromate. The disaccharide, sucrose, significantly increased accumulated matter on substrates, but dextrose did not elicit similar responses. Phosphate and ammonium nitrate additions did not cause significant increases in aufwuchs production and were not considered to be limiting in this system. Net microbial productivity of aufwuchs and primary productivity were estimated by assimilatory sulfate reduction and carbon-14 fixation, respectively, with heterotrophic productivity being the difference. Overall, the reduced carbon compounds (sugar) and the toxicants resulted in stream aufwuchs communities dominated by heterotrophs. Indices used for condensation of information in the model stream experiments were generally unsuccessful in discerning perturbations. From all of the model stream experiments, measurements of functional parameters or indices calculated from functional measurements were significantly less variable than structural measurements or structurally based indices The perturbations or treatments did not reduce variability in the nontaxonomic structural and functional aspects measured. Direct correlations were found between: 1) dry weight and ash-free dry weight, 2) ash-free dry weight and assimilatory sulfate reduction, 3) ash-free dry weight and chlorophyll a, 4) chlorophyll a and assimilatory sulfate reduction, 5) chlorophyll a and primary productivity, 6) primary productivity and assimilatory sulfate reduction, and 7) and primary productivity and net microbial productivity. Field investigations of aufwuchs communities in the vicinity of a fossil-fueled power plant on the New River, Virginia, were inconclusive Variability in measurements overshadowed any differences in nontaxonomic structural and functional aspects that might have been attributed to an intermittently chlorinated thermal effluent. / Ph. D.

The rates of penetration, metabolism, and excretion of DDT have been studied in vivo in resistant and susceptible strains of the German cockroach, Blattella germanica (L.). The cockroaches were exposed to various DDT treatments for intervals ranging from 3 to 72 hours. DDT and its metabolites were identified and quantitated in external, internal, and excreta fractions using gas-liquid chromatography. The identifications were verified by thin-layer chromatography. It has been shown that DDT penetration is nearly identical for the three cockroach strains used in this study (two resistant and one susceptible strain). For this reason penetration is not thought to be related to the DDT resistance mechanism in this insect. Susceptible and resistant cockroaches are both capable of converting DDT to dicofol which was the only metabolite observed. The conversion rate is somewhat faster in the resistant strains than in the susceptible strain but in no case exceeds 20% of the absorbed dose. Dicofol production reaches a maximum which is not exceeded in the presence of additional DDT. Female cockroaches of all three strains convert DDT to dicofol at a faster rate than their respective males. The inhibition of dicofol production by the synergist sesamex occurs at a high level in all strains, but results in mortality in the susceptible strain. Therefore, metabolism does not seem to be a major resistance mechanism. Excretion of unchanged DDT is apparently not related to the observed resistance levels. The excretion mechanism is, however, capable of removing much of the penetrated DDT provided the insect can survive the treatment. Excretion of DDT was consistently higher in male cockroaches than in females. The combined effects of the detoxication and excretion mechanisms are extremely efficient in removing penetrated DDT from this insect, particularly at higher treatment levels. Never-the-less, resistant cockroaches have and can apparently withstand much higher internal concentrations of DDT than susceptible cockroaches. The DDT-resistance mechanism of these cockroaches appears to be similar in nature to the unknown mechanism responsible for resistance to knockdown (Kdr) or paralysis by DDT in houseflies. This mechanism may alter the site of action of DDT and result in a reduced binding capacity of resistant insect nerve tissue for the DDT molecule as compared to susceptible insect nerve tissue. / Ph. D.

One of the most critical urban problems is the ever-increasing demand for transportation facilities. An alternative for reducing the degree of peak-hour congestion is to increase the passenger movement capability of a facility by providing exclusive bus lanes. The Shirley Highway Express-Bus-on-Freeway Demonstration Project was implemented to test the hypothesis that the provision of rapid and convenient bus service over an exclusive lane would attract significant numbers of automobile passengers. Such a diversion would improve the passenqer movement and relieve the congestion of the facility, thus, resulting in an improved level of service for all travelers. This study was an evaluation of the project, and the main objectives were: 1. Determine the effects of the busway on bus patronage and automobile travel. 2. Analyze the sources of bus patrons and determine the reduction in automobiles. 3. Use the automobile reduction in comparing the level of service for the existing facility to the freeway without the exclusive busway~ In approaching these objectives, the study identified and evaluated such parameters as travel times, passenger and vehicular volumes, commuter profiles, and occupancy rates. Speed-volume-capacity relationships were used to compare the quality of service on the existing facility to a hypothetical roadway without an operational busway. The analysis revealed a large increase in bus patronage and a reduction in automobiles and congestion on the Shirley Highway. The existing facility was providing acceptable service, while the demand on the hypothetical roadway exceeded the capacity. / Master of Science

An attempt was made to study the effects of a tranquilizer (metoserpate hydrochloride), specifically designed for poultry, on the neonatal approach response of domestic chicks. Acquisition of this response was accomplished in a straight alley on birds ranging in age from 24 to 120 hours old. Testing of this response was done when all birds were 144 hours old under a no-drug condition. At 168 hours of age all subjects were subjected to extinction procedures. The strength of the response was measured in terms of latency to start as well as time spent traversing the alley. Resistance to extinction was measured in terms of the latencies mentioned above as well as number of trials to extinction. The results of the present study show a peak in imprinting susceptibility between 72 and 96 hours after hatching. The tranquilizer had a traditional interference effect except for those birds exposed on Day 3 while the injection control procedure had an enhancement effect on birds treated on Days 4 and 5. In addition, there were no differences observed during extinction between groups. / Master of Science

An investigation has been conducted to determine the effects of jet-to-free-stream dynamic pressure ratio on the penetration and mixing of a sonic hydrogen jet injected normal to a Mach 4 airstream. The hydrogen gas was injected from a circular nozzle flush mounted in a flat plate with a turbulent boundary-layer thickness of 2.70 injector exit diameters at the injector station. The investigation was conducted for values of the dynamic pressure ratio ranging from 0.5 to 1.5. At five downstream stations between 7 and 200 injector diameters the mixing region was surveyed to obtain hydrogen volume concentration and pressure profiles. Results of the investigation indicate that the thick boundary layer had significant effects on the penetration and maximum concentration trajectories when compared to data correlations from other sources. The penetration trajectory was found to be proportional to the dynamic pressure ratio raised to the 0.3 power. The decay of the maximum concentration was very rapid in the near field and inversely proportional to (x/dj)^0.8 at downstream distances greater than 30 jet diameters. At a particular value of x/d the maximum concentration was proportional to q_r^½. Nondimensional concentration profiles, represented by Gaussian-type functions, on the vertical centerline showed similarity at values of x/d equal to or greater than 60. / Master of Science

No description available.