Computer aided diagramming (CAD) tools today are based on the approach of a fixed symbol into which text is fitted. This approach leads to shortfalls in human interfacing and tool development. The inverse view of entering the text and then drawing the symbol around it provides the basis for an innovative approach that is more natural and user friendly. This report documents benefits realized from the new approach in the development of a CAD tool referred to as DiagramEdit. / Master of Science / incomplete_metadata

A method was developed for estimating costs of harvesting operations in the hardwood stands of the Appalachian region of southwestern Virginia. The method was then tested on one logging operation to estimate the cost of harvesting a group selection tract as compared to a clearcut. Eight loggers were contacted and interviewed to obtain data on their costs of logging. The mean, median, and standard deviation of the responses were calculated to develop a profile. Mean crew size was three men, including the owner operator. Mechanized equipment consisted of a cable skidder from 75 to 120 hp. and a small to medium size loader. Average skidder age was 4.8 years. Loggers produced 144 cords per week, of which 54.6% was pulpwood and 42.4% sawtimber with 3% firewood. Products were hauled an average of 33 miles one way. Labor costs, including wages and all benefits averaged $411 per man per week. Total harvesting costs had a mean of $2252 per week. Mean hauling cost was $1289 per week. Annual production averaged 6778 cords. Cords per man hour was 0.99. Total cost per cord including hauling averaged $26. The information taken from the interviews was incorporated along with data from current literature into the Harvesting Analysis Technique (HAT), a main frame harvesting simulator, to model group selection harvests against clearcut harvests. A twenty-seven acre group selection cut was compared to a 160-acre clearcut. Clearcut area was based on the access estimated possible by the group selection skid road network. Results showed group selection harvested at a 21% slower rate than clearcutting. Harvest cost per cord was 25.8% greater. Variation in cost was caused mainly by the increased average skid distances present in the groups. Every 100 foot increase in skid distance resulted in a $0.68 increase in cost per cord for skidding in group selection harvests compared to a $0.33 increase for clearcutting. / Master of Science

A viable sludge management alternative is land application of waste sludge. However, it is necessary to implement efficient monitoring and analysis of land applied sludges in order to assess potential health risks associated with this means of disposal. The State of Virginia is considering a proposal that requires land-applied wastewater sludges to undergo analysis by EPA's Toxicity Characteristic Leaching Procedure (TCLP) (EPA, 1986b) to determine if the sludge exhibits hazardous characteristics, which preclude land application as a management alternative. The method currently used for the analysis of hazardous wastes is the Extraction Procedure (EP) Toxicity Test. Both of these test methods analyze for trace organic chemicals and heavy metals. However, the TCLP is designed to analyze for volatile organic chemicals to a greater extent than the EP. Because of the added complexity and the current expense of the TCLP, the State is concerned that the TCLP may not be warranted for the analysis of trace organic chemicals in land-applied sludges. This research was designed to compare the abilities of the EP and TCLP for the analysis of trace organic chemicals in wastewater sludges. Samples from three municipal wastewater treatment plants that utilize secondary biological treatment, aerobic digestion and land-apply waste sludge were evaluated by both EP and TCLP methods. Both tests utilize a weak acid extraction to remove organic chemicals from the wastewater sample. The weak acid extract was subjected to liquid-liquid extraction (EPA Method 625) to partition and concentrate the organic chemicals into methylene chloride; this methylene chloride extract was then subjected to GC and GC/MS for quantitative analysis and qualitative identification of targeted and nontargeted organic chemicals. In order to assess recovery and extractability efficiencies of each test, surrogate standards were added prior to the test procedure. These standards were bromoform, 1-chlorooctane, DDT, ethylene dibromide (EDB, a volatile fungicide), fusarex (tetrachloronitrobenzene), and heptachlor. Control samples were run for both EP and TCLP, in addition to a sludge samples with no surrogates added. Analysis indicated that both the TCLP and EP tests showed high variability for the recovery of the sludge surrogates. The recoveries of the surrogate standards were low and varied between zero and 30 percent depending on the standard and the matrix. Surrogate recoveries were evaluated with respect to various physical/ chemical properties of the individual standard, the sample site, and the test method utilized. Although the TCLP recovered the volatile surrogate standards only slightly better than the EP, there was no statistically significant difference between the TCLP and EP for the recovery of the non- and semi-volatile surrogate standards. Specific trace organic chemicals identified in the sludges included dimethylpentanol, dichlorodimethoxybenzene, 4-methylphenol, and tetrabutylphenol. Other chemicals, such as contaminants and artifacts resulting from laboratory processing and background contamination in the reagents, were also identified in the blank control samples as well as the sludge samples. / Master of Science

Studies were performed to determine the effect of color modification procedures on the microbial characteristics of turkey thigh meat. Turkey thighs were flaked and then color modified successively with three sodium phosphate buffers (pH 5.8, 7.4, and 8.0). At selected time intervals, flaked unwashed turkey (FUT; control) and color-modified turkey (CMT) stored at 3°C were analyzed for aerobic, psychrotrophic, and coliform bacterial counts. Aerobic and psychrotrophic numbers also were estimated in raw tissues held at -20°C. Cooked FUT and CMT were inoculated with two strain composites of either Salmonella or Listeria monocytogenes and held at 4 and 20OC. Salmonella enteritidis, Salmonella typhimurium, Q. monocytogenes Scott A, and a Q. monocytogenes meat isolate were organisms used in the inoculation studies. Aerobic and psychrotrophic counts were not different (p >0.05) at any sampling interval when numbers in raw EUT were compared to those in raw CMT. Coliform counts in raw FUT did not differ from those in raw CMT (p >0.05) after l day at 3°C. In inoculation studies, numbers of either pathogen generally did not differ (p >0.05) I between cooked FUT and CMT at selected sampling intervals. Salmonella counts declined gradually in cooked samples held at 4°C. By day 3, Salmonella levels increased more than 6 logs in tissues held at 20°C. L. monocytogenes counts increased approximately 5 logs in cooked FUT and CMT held at 4°C for 14 days. Numbers increased more than 5 logs in samples stored at 20°C for 48 hr. Although a significant (p <0.05) factor in some studies, color modification was not considered to have a major effect on microbial growth in altered thigh. / Master of Science

A comparative study of the RISC philosophy of implementing mathematical functions vs the CISC. philosophy implementing the same functions is undertaken. This study tries to verify whether, the RISC philosophy is suited for the computers designed to run specific applications like the realtime systems. A CISC processor is used as a platform machine and several mathematical functions are implemented in both the philosophies. / Master of Science

A model describing the potential amino acid ligands to the four 4Fe-4S centers (P-clusters) within the Azotobacter vinelandii nitrogenase MoFe protein is presented. Based on interspecies and intersubunit amino acid comparisons of the α- and ß-subunits of the MoFe protein, and the FeMoco biosynthetic proteins, NifE and NifN, four conserved residues (Cys62, His83, Cys88, Cys154 all proposed P-cluster ligands) within the α- subunit were targeted for site-directed mutagencsis studies. In order to define a range of acceptable substitutions, 35 specific site-mutants have been constructed, each with a different amino acid replacement at one of the four targeted positions. Previous studies indicated that these residues were important for MoFe activity, and may act as metallocenter ligands. Unusual redox and spectroscopic properties of the Fe-S centers suggest the involvement of ligands other than the four typical cysteines, though extrusion requirements indicate that some thiol ligands are likely. Surprisingly, mutants with an Asp, Gly, Thr, or Ser substituted for Cys88 are still capable of diazotrophic growth (Nif+), though whole cell and crude extract acetylene reduction activity is lowered. Several substitutions (Cys, Asp, Phe, Asn, Met, Tyr, Leu) are tolerated at the His83 position, these Nif+ mutant strains also have varying acetylene reduction rates and growth rates. All mutants with substitutions at positions 62, 154, resulted in complete loss of diazotrophic growth. The results could be interpreted by the following explanations: 1) Our proposed model for the P-cluster ligation within the MoFe protein is incorrect. 2) Some substitutions permit P-cluster rearrangement to a semi-functional state. 3) Either, P-clusters are not absolutely essential for diazotrophic growth, or the enzyme can function with a reduced number of these metal centers. / Master of Science / incomplete_metadata

Soil moisture distribution resulting from a line source subsurface trickle irrigation system was studied on bare and cropped layered soils. The soil type was an Uchee loamy sand. The Continuous System Modeling Program (CSMP) Model was used to simulate the soil moisture distribution resulting from the linesource. The model was modified and developed in FORTRAN programming language. The modification included the effects of layered soil, source position, number of sources, soil evaporation and plant transpiration. The model was also used to simulate daily and one-in-several-days irrigations. Field and laboratory experiments were conducted to determine the soil moisture retention curve, the hydraulic conductivity, and soil moisture distribution from the line source. This data was used for model verification with the lateral lines buried 13 inches below the soil surface and spaced 36 and 72 inches apart. Simulated and measured soil moisture distributions were in good agreement. Simulated moisture distribution indicated that the wetting front expansion is more a function of irrigation volume than irrigation rate. However, the irrigation rate does affect the soil moisture distribution. A higher rate will result in a larger quantity of horizontal water movement. The simulation also indicated that a one-in-ten days irrigation causes more horizontal movement than a daily irrigation. / Master of Science

The relative effectiveness of noncontiguous cartograms, in presenting data were tested over a continuum of tasks ranging from general to specific, using university students as subjects. A total of three tasks were examined, one task required subjects to judge cartograms showing a very general distribution, the second task required a moderate amount of information to be retrieved, and the third task required very specific information to be obtained from the cartogram. Two sets of non contiguous cartograms of the United States were used; one set had international and internal boundaries the second set had only international boundaries. In general students performed task one and two with a great deal of accuracy, proving non contiguous cartograms are a useful method of displaying geographic information. The third task was less successful than the first two, although this fact is not surprising, we learned that when displaying and trying to retrieve very specific kinds of information, the non contiguous cartogram is not a viable option. / Master of Science

Experiments were performed with anaerobically digested sludge and a plate and frame filter press to determine filter press performance over a range of polymer doses and under a variety of sludge and polymer mixing conditions. In addition, bench-scale polymer dosing and mixing experiments were conducted with the same sludge samples to determine the relationship between the bench-scale tests and actual plate and frame filter press performance. Dewatering rate was measured in bench- scale experiments with a Capillary Suction Time (CST) device and dewatering rate in pilot-scale experiments was quantified by measuring the volume of filtrate from the plate and frame press. The dimensionless quantity, Gt, was used to measure total mixing intensity input where G was the mean velocity gradient and t was the mixing time for the sludge and polymer. The performance of the plate and frame filter press was optimized by predicting polymer dose with a bench-scale mixing device. For the plate and frame filter press used in this study, the polymer dose was selected by finding the optimum polymer dose for the bench-scale mixing system set at a Gt value of 30,000. The sludge and polymer were mixed with a Gt value of 5000 prior to introduction to the filter press. The polymer dosing and mixing scheme that was developed for the filter press in this study indicates that the filter press imparts some shear (G) on the sludge and that polymer must be provided to reagglomerate fractured sludge particles. An estimate of the Gt value for the filter press that was used in this study is 15,000 to 40,000. / Master of Science

The boxelder bug, Boisea trivittata (Say), is a pest because large numbers congregate on and in buildings, causing concern among homeowners. More knowledge of effective insecticides, seasonal abundance of the pest, and concerns of the affected homeowner will help to reduce the impact of the insect in urban areas. Field-collected adults and nymphs exposed to latex-painted surfaces treated with 0.1% cypermethrin, 1.0% diazinon, 0.25% bendiocarb, 0.25% chlorpyrifos, and 1.0% propetamphos resulted in more than 70% mortality with all insecticides up to 3 d after treatment for adults, and 7 d after treatment for medium-and large-sized nymphs. Fewer than 50% of homeowners surveyed thought boxelder bugs were a serious pest. Homeowners had little knowledge about the source of infestations from host trees. Residents reported spending $22.42 (median) to control boxelder bugs, but were willing to spend $45.00 (median). Residents tolerated more bugs outside (median=63) than they would inside (median=8) their house. From April to December, 1988, boxelder bug populations were sampled outdoors in urban areas. First generation nymph and adult populations peaked during June and July. Fall generation nymph and adult populations were abundant on the ground and trees from August to September, but not on residences. Movement to the ground and surfaces of buildings occurred in October, and adults peaked in numbers in mid November. Temperature profiles on residences and behavioral observations indicated that boxelder bugs found on host trees orient toward sunlight; adults were found in greater numbers on surfaces with higher mean temperatures than other substrates. / Master of Science / incomplete_metadata