Academic literature on the topic 'LD5655.V851 1991.B666'

The site for this seminary is located within the northwest quadrant of the District of Columbia. The site consists of a ridge approximately one hundred and ten feet in elevation bounded by Clark Street at its north western tip and a rocky promontory a quarter of a mile to the southeast. Along its southwestern edge lies Canal Road, the C&O Canal and the Potomac River. To the northeast lies upper Georgetown. My intention was to utilize the natural axis of the ridge to construct a clear line of demarcation between the secular world and the world of religious education and scholarship. It was clear from the beginning that the site had to be developed in accordance with the natural orientation and steep topography of the ridge. The clearest means of access to the site exists to the north east along an abandoned rail bed that intersects Fox hall Road. The new road to be constructed within this depression constitutes the first in a series of moves to create a datum line between the natural setting of the seminary and the urban fabric of Georgetown. Parallel to this road lies a continuous reflecting pool eight hundred feet in length. This second element of separation is broken only at the entry to the seminary. The third and final element of separation is an extended wall that defines both the natural orientation of the site and the linear structure of the seminary. From the northwest it extends over one thousand feet to the southeast. Like the reflecting pool, the datum wall is broken only at its single point of entry. The structure of the seminary can be viewed in its entirety from the southwest. It is a linear composition with a semi-circular terrace at its entry which forms an open air cloister. On either side stand the auditorium and lecture spaces, administrative facilities, library, refectory, seminarian cells, chapel, terrace and bell tower.<br>Master of Architecture

Turbulence research in the laboratory has confirmed the existence of quasi-coherent structures amidst the chaos of a turbulent boundary layer. It has been observed that a quasi-periodic phenomena called “bursting” accounts for a major contribution to the turbulent Reynolds stress and the production of turbulent kinetic energy. Bursting is the term used for a sequence of events, where a low-speed streak of fluid from the near wall region lifts away from the wall, slowly at first, and then rapidly moves away from the wall as it convects downstream where it becomes unstable and breaks up violently upon interaction with the outer flow. This ejection of low speed fluid into the mean flow is responsible for locally high values of turbulent kinetic energy. Although a great deal is known about these structures in laboratory flows, little has been done to investigate if such structures are universal in turbulent flows, i.e., their existence in large Reynolds number flows such as the turbulent air flow over the ocean. It would seem, intuitively, that such structures, if present in the marine atmospheric boundary layer, would play a major role in the transfer of momentum, mass and heat across the air-sea interface. It is speculated that these motions may also be associated with large scale organized motions in wall bounded turbulent shear flows. The effort aimed at elucidating the physics underlying such structures would be invaluable in contributing to our understanding of the air-sea flux mechanism. In this dissertation, standard ejection detection schemes like the quadrant, the VITA and the modified u-level techniques have been applied to turbulent wind data measured over the ocean to confirm the existence of burst like structures. The proportions of contributions to the Reynolds stress from the four quadrants of the u’w’ plane are in close agreement with the corresponding contributions for a laboratory flow. Ejection detection followed by the grouping of ejections into bursts yielded a mean burst period of 47 s, at a height of 8.2 m above the water surface, where the mean wind velocity was 6.74 m/s. This burst period corresponds well with the peaks obtained from the autocorrelation of the streamwise velocity signal and the first moment of the stress spectrum, confirming the quasi-periodic nature of this phenomena. Furthermore, phase averages of these events show a structure which is similar to the structure of events detected in laboratory flows. The ejection periods are seen to decrease with increasing wind speed. The burst periods decrease at first with increasing wind speed and then appear to attain a constant value after a wind speed of 6-7 m/s. This has been attributed to the breakdown of the grouping algorithm at higher wind speeds. Ejection and burst frequencies exhibit no discernible dependence on the surface wave field. Ejection and sweep motions have been studied at various length scales. The original velocity signal is bandpass filtered for various frequency bands. For each band, the percentage contributions to the Reynolds stress from the quadrants of the u'w’ plane are close to the corresponding quadrant contributions of the other bands. This indicates similar turbulence structure at different scales. The velocity signals for each band have been normalized by their root mean square (RMS) value. Visualizing the signals on nondimensional time shows the signals from each band to be very similar. These results can also be interpreted as evidence for the ejection and sweep motions existing simultaneously at different scales, indicating the fractal nature of these events. Large scale motions, which appear to be associated with ejection and sweep motions, have been identified in the marine atmospheric surface layer using velocity probe measurements at multiple heights. Visualizing these velocity signals suggests that the organized features extend across the depth of the surface layer. Converting the temporal signals to spatial fluctuations suggests that these structures are inclined at an angle while convecting downstream. The inclination angle near the surface (z < 18 m) is approximately 15° and it increases with increasing height to about 45° when z = 45 m. The spatial velocity fluctuations also indicate that these organized features may be large transverse vortical arches.<br>Ph. D.

Tumor necrosis factor-a (TNFa) is primarily a macrophagederived cytokine. TNFa, in vitro, kills or inhibits growth of approximately one third of surveyed transformed cell lines dincluding the L929 and WEHI 164 murine fibrosarcoma cell lines. Very little is known about the mechanisms of TNFa action. However, recently, it has been theorized that TNFa has no activity of its own and that the receptor for TNFa on the cell surface, when properly triggered, activates the cellular mechanisms which may result in the cell's death. The objective of this study was to produce an antiidiotypic antibody to TNFa to be used as a tool to study the mechanisms of TNFa action. A hybridoma that secretes an antiidiotypic antibody to TNFa (Ab2J1) has been produced and isolated following standard procedures. This antibody was found to be of isotype IgG2a as determined by an indirect ELISA test. The Ab2J1 exhibited TNFa target cell-killing capabilities in vitro. The TNFa-resistant cell lines, SP2jO and NS-1 were resistant to Ab2J1 and TNFa sensitive cells, L929 and WEHI 164, were sensitive to Ab2J1. The cell killing activity of both TNFa and Ab2f3 could be neutralized by a monoclonal anti-TNFa antibody. Both TN Fa and Ab2f3 acted in parallel having an effect on the killing of Brucella abortus strain RB51 by peritoneal macrophages, whereas neither TNFa nor Ab2f3 had an effect on the killing of strain 2308 by macrophages. These results, again indicate that TNFa and Ab2f3 have parallel dbactericidal effects and that Ab2f3 is capable of mimicking TNFa activity. The Ab2J1 was further characterized by gel electrophoresis and Western blot and was found to have two subunits of 25 and 50 kDa molecular weights similar to IgG. This anti-idiotypic antibody to TNFa may help in understanding the mechanisms of the cytotoxic activity of TNFa.<br>Master of Science

This dissertation discusses a new approach to spline approximation. A periodic spline approximation 𝑓_M,m,N(x) = Σ_k=1^Nα_kΦ_M,k(x) to a periodic function 𝑓(x) is determined by requiring < Φ_m,j, 𝑓 - 𝑓_M,m,N > = 0 for j = 1,...,N, where the Φ_L,k's are the unique periodic spline basis functions of order 𝐿. Error estimates, examples and some relationships to wavelets are given for the case M - m = 2μ. The case M - m = 2µ + 1 is briefly discussed but not completely explored.<br>Ph. D.

Industrial toxicity has become a major environmental subject over the past decade. Although much research and data have been collected and published for the manufacturing type industries, minimal data is currently available concerning the possible toxics that may be associated with coal mining industry NPDES discharges. Thus, in this report, an environmental toxicity assessment with respective data shall be presented on the three major constituent sectors of the coal mining industry in Southwest Virginia of which includes mines, preparation plants and refuse facilities. The mines category shall include both surface and underground facilities. The preparation plants sector will cover the traditional railroad siding loadout type facilities, along with the modern clean coal processing preparation plants. Valley and side fill configuration, coarse and combined refuse fills and coal refuse impoundments shall be presented in the refuse facility categorization. Reference source data and specific information from a Virginia Coal Association Taxies Monitoring Program study are presented to show that the effects of toxicity in the coal mining associated NPDES effluents are minimal and not a serious problem. The conclusions of this report shall show that through enforcement of better management practices within the coal industry in Southwest Virginia that toxicity can be virtually eliminated in NPDES outfalls.<br>Master of Science

Several methods have been developed to determine the cyclic oligomer content in PET. Isolation procedures can be classified as those involving extraction, such as with solvents like chloroform, dioxane, and xylene, and those involving dissolution followed by precipitation in solvents like dimethylformamide and 1-methylnaphthalene. The amount of cyclic oligomer obtained is largely dependent upon the method used, as well as the type, drawing, and thermal history of the PET used.Various methods for separation of cyclic oligomers have also been developed using GPC and thin-layer chromatography.<br>Master of Science