• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • Tagged with
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Plasmid deoxyribonucleic acid of strains of the saccharolytic intestinal Bacteroides

Mays, Thomas Dale 12 September 2012 (has links)
A collection of 120 strains of saccharolytic intestinal Bacteroides was examined for plasmid deoxyribonucleic acid (DNA). These strains were previously characterized for standard phenotypic properties (variety of carbohydrates fermented, metabolic end products, and complex carbohydrate hydrolysis). Additional phenotypic characterizations included bacteriocin production, cell wall analysis, and antibiotic susceptibilities. The interrelatedness of the strains had been determined by DNA homology experiments. The strains were distributed among 10 major DNA homology groups or genospecies. Plasmid DNA was found in 52 strains (43%) distributed among all ten major DNA homology groups. The plasmids ranged in size from 2 to 65 megadaltons (Mdal) as estimated from their migration distance in agarose gels during electrophoresis. A small plasmid of 2 to 6 Mdal was found in 42 of the plasmid bearing strains. Seventeen of these strains also contained larger plasmids (20 to 65 Mdal). Ten strains contained only a large plasmid. There was no apparent correlation between the presence of any particular plasmid size with the DNA homology grouping of the host strains. Size estimations calculated from plasmid DNA reassociation curves (C₀t curves) agreed with the agarose gel electrophoresis size determinations. Four plasmids were selected for reference use in DNA homology studies. They were isolated from B. fragilis strains 2553 and 4076, B. thetaiotaomicron strain 5482, and B. uniformis strain T1-1 respectively. These plasmid preparations were radioactively labeled in vitro using the 4 deoxyribonucleic triphosphates (³H labeled thymidine 5'- triphosphate) and Escherichia coli B polymerase I. The percent guanine plus cytosine content of two duplexed plasmid DNA preparations was determined by comparing their thermal stabilities with those of duplexed DNA from three bacterial strains whose percent guanine plus cytosine contents were known. Plasmid DNA p4076 and p5482 were found to have a percent guanine plus cytosine content of 39 and 43 respectively. Three of the reference plasmids (p2553, p4076, and p5482) were large species (22 to 23 Mdal) and did not have any significant base sequence homology with one another. The small reference plasmid (pTl-1, 3 Mdal) had 30% DNA homology with the p4076 reference plasmid. Plasmid DNA preparations from all the plasmid carrying strains were allowed to renature with each of the labeled reference plasmids. Many of these plasmid DNA preparations contained multiple plasmid species. The pT1-1 reference plasmid had moderate (30 to 60%) or higher (61 to 100%) DNA homology with 35 of the plasmid DNA preparations. The reference plasmid DNA, p2553, had moderate or high homology with 10 unlabeled plasmid preparations while the p5482 reference plasmid had similar homology with 9. The p4076 reference plasmid did not have significant base sequence homology with any of the plasmid DNA preparations. Several strains contained plasmid DNA that had homology with both pTl—1 reference plasmid and one (but not both) of the larger reference plasmids (p2553 and p5482). The homology between the unlabeled plasmid DNA preparations and the two reference plasmids may be due to either separate or hybrid plasmids. This was not determined. A computer analysis of 81 phenotypic traits was made, comparing each with the plasmid DNA homology groups. No significant correlation was noted. Plasmid—mediation of bacteriocin production was considered, but there was no correlation between bacteriocinogenesis and the occurrence of any plasmid DNA homology group. / Ph. D.
2

The development and analysis of a multi-attribute quality control cost model

McCaslin, James Albert, 1948- January 1973 (has links)
A multi-attribute quality control cost model is presented in this thesis. The mathematical model expresses the expected total cost of the quality system per lot as a function of the decision variables, nᵢ and cᵢ, i = 1, 2, . . . , m, where nᵢ is the sample size for the ith attribute. cᵢ is the acceptance number for the ith attribute. m is the number of attributes. The expected total cost is denoted by C<sub>T</sub> and can be expressed as C<sub>T</sub> = E (cost of sampling inspection). E (cost of accepting the lot). E (cost of rejecting and scrapping the lot). E (cost of rejecting and screening the lot). An optimal sampling plan can be obtained by determining the nᵢ and cᵢ, i = 1, 2, …, m, that minimizes C<sub>T</sub>. The nᵢ and cᵢ are found by means of a search technique that has proved useful in attribute quality control systems. In addition to the model development and optimization, a sensitivity analysis is performed on the use of the gallllla distribution as an estimate of the true process distribution for single and triple attribute systems. Also, a model sensitivity analysis is performed on errors in the estimation of the Cₐᵢ, the cost of accepting a defective unit. / Master of Science
3

An investigation of the possibilities within the limitations of prefabrication in housing today

McBride, John David January 1970 (has links)
This thesis is the development of a design program. Current housing systems, while offering a shelter, provide very little more in terms of differentiation and variation of units, or any selection on the part of the resident. This is termed the minimum solution and can, result in monotonous housing developments, discontent among inhabitants, and in general, dislike for "prefabricated houses.” But, through re-evaluation of design priorities, and developing the maximum solution, which does contain many variations and a wide selection for the owner, an industrialized system of building can offer each person a unique unit and in turn, make "prefabricated houses" desirable to live in. / M. A.
4

A New Look at Hard Labor Creek Observatory

Moore, Robert D, Jr 16 April 2012 (has links)
This document presents a study of astronomical observing conditions of Hard Labor Creek Observatory. Analysis of factors such as sky brightness, astonomical seeing, and patterns in the level of cloudiness at the site are presented. Characteristics of the observatory's Apogee Alta U230 camera are also measured and calculated. These characteristics include loss of linearity in the CCD's response to light, read noise, gain, dark current, and stability in the camera's bias levels. The camera is also used in conjunction with the 20-inch RC Optics telescope to determine the system's pixel scale and a set of limiting magnitudes for the Johnson-Cousins photometric filters that are used with the camera. Observations of a transit of known transiting exoplanet Qatar-2 b as well as observations of the open cluster Messier 29 are also performed to demonstrate the ability of the equipment to perform precise photometric observations.

Page generated in 0.0383 seconds