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The exponent and circumdiameter of primitive directed graphsDame, Lorraine Frances. 10 April 2008 (has links)
No description available.
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Kernels and quasi-kernels in digraphsHeard, Scott. 10 April 2008 (has links)
No description available.
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The reversing number of a digraph /Narayan, Darren Amal. January 2000 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaf 70).
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Exciton transfer and trapping in photosystem IIMerry, Stephen Alan Paul January 1998 (has links)
No description available.
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An investigation into formal models of change in artificial intelligenceAyesh, Aladdin January 1999 (has links)
No description available.
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Evolution of copper-containing nitrite reductaseMacPherson, Iain 05 1900 (has links)
Copper-containing nitrite reductase (NiR) is a homotrimer of two cupredoxin domains and catalyzes the single electron reduction of NO2- to NO during dissimilatory denitrification. To investigate the evolution of NiR, methods of mutagenic library generation and high-throughput variant screening from E. coli colonies were developed. These methods allow for facile screening of 105 mutants for folding efficiency or substrate specificity. Initial proof of principle studies yielded several variants that oxidized the artificial substrate ο-dianisidine up to 8 times faster than wild type NiR, suggesting that this methodology has the potential to engineer NiR to acquire other reductase functions.
A crystal structure was solved for a putative multicopper oxidase (MCO) and NiR homologue from Arthrobacter sp. (AMMCO) to 1.8 Å resolution. The overall folds of AMMCO and NiR are very similar (r.m.s.d. of 2.0 Å over 250 Cα atoms); Like NiR, AMMCO is a trimer with type-1 Cu sites in the N-terminal domain of each monomer; however, the active site of AMMCO contains trinuclear Cu site characteristic of MCOs instead of a the mononuclear type-2 Cu site found in NiR. Detailed structural analysis supports the theory that two-domain MCOs similar to AMMCO were intermediaries in the evolution of NiR and the more common three-domain MCOs. The physiological function of AMMCO remains uncertain, but genomic, crystallographic and functional analysis suggests that the enzyme is involved in metal regulation.
Considering the extensive similarity between AMMCO and NiR, particularly at the active site, engineering a trinuclear cluster into NiR appears feasible with a modest number of alterations to the polypeptide chain. With the aid of my newly developed high-throughput screening technique and site-directed mutagenesis, the mononuclear NiR active site was remodelled into a trinuclear Cu site similar to that of MCO. A crystal structure of this variant was solved to 2.0 Å and the presence of three copper atoms at the engineered cluster was confirmed by Cu-edge anomalous diffraction data. Although the trinuclear copper cluster is present and catalyzes the reduction of oxygen, achieving rates of catalysis seen in native MCOs has proven more difficult. With the framework provided, further engineering NiR into a robust MCO is likely to provide further insights into the structural basis of oxygen reduction by trinuclear copper sites.
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Developing a decision model to describe levels of self-directedness based upon the key assumptions of andragogyRichards, Lance Jonathan 01 November 2005 (has links)
As workplace demands change, a need has developed for alternatives to traditional
education. With advancements in electronic telecommunication technologies, distance
education has become a viable alternative to traditional classrooms for working
professionals. Efficiency and cost effectiveness are driving many programs to place oncampus
students and distance students in the same courses at the same time. This
phenomenon has resulted in the placement of students with vastly different backgrounds,
levels of expertise, and levels of motivation in the same classrooms. Often a professor
will teach to one learning style, leaving some students in the dust, never to get on track.
Without face-to-face contact with an instructor, this can leave distance education students
feeling isolated and alone.
There is a continuing need for the development of alternative instruments to
assess self-directed learning (Brockett & Himestra, 1991). We must develop a means of
determining an individual??s readiness for self-directed learning, as well as a device for
measuring the efficiency of programs designed to foster the attitudes and skills which are
involved in increased self-directedness in learning (Guglielmino, 1977). Self-directed
learning readiness is important to a learner??s success in distance education programs. Inorder for an educator to tailor instruction to the unique attributes of each student, there is
a need for an instrument that will identify the learner??s stage of self-directedness or
degree of dependency and for an instrument that will determine the educator??s default
teaching style at the beginning of a course. Such an instrument will help instructors
increase their learners?? level of self-direction and will improve the overall quality, student
satisfaction, and student retention in distance learning courses.
The purpose of this study is to develop and pilot test two instruments based upon
the Staged Self Directed Learning Model (Grow, 1991) and the key assumptions of
andragogy: one measuring the self-directed learning readiness of a student in the context
of an individual course and the other measuring the teaching style of the instructor in the
context of the same course. The data will be analyzed and given to the instructor to give
him/her an idea of the self-directed learning readiness level of students enrolled in the
course. A report will be generated to show matches and mismatches between the
instructor??s teaching style and the self-directed learning readiness level of the students. A
decision model will be developed to suggest teaching strategies that minimize
mismatches and facilitate the growth of students from dependent to self-directed through
the course.
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The role of andragogy and self-directed learning in the draft horse industryHynes, James William 16 August 2006 (has links)
The purpose of this study was to determine and understand the variables
affecting the revival of the draft horse industry in the United States. A qualitative study
was conducted using 31 purposively (Lincoln and Guba, 1985) selected draft horse
industry participants who were drawn from three case studies, conducted in East Texas,
Russia (Siberia), and Northern Indiana. Structured and semi-structured interviews were
utilized. Major findings emerged with this research showed that the culture of
practicality, inventiveness, and risk taking has allowed communities of individuals to
achieve financial success where others have been forced to abandon their businesses and
seek other sources of livelihood.
Some of the findings stood alone with no seeming connection to the other
findings. Other findings appeared to be intertwined with one another. All of the
emerging findings contributed to the renewal and engagement of individuals in the draft
horse industry revival. The findings are deliberately not listed in any particular order.
The scope of the study did not include a method to determine whichfinding or series of findings preceded the others. The major findings to emerge from this
study are as follows.
Most of the participants in the revival were or are middle aged men and women.
This finding melds well with another finding that determined the draft horse business
was the second, third, or fourth career of the participants in this study. Many of the
participants operate their businesses in rural non-farm locations. Owners and publishers
of trade magazines played a pivotal role in this industry revival.
Geography and international connections played a role. The Amish communities
across the U.S. played a pivotal role in keeping relic technologies alive and maintaining
seed stock for the revival of the draft breeds. Specific markets for horses and equipment
have been carved out by many of the participants. Self-directed learning and andragogy
were exhibited by almost all of the participants. The role of university and extension
personnel in this revival was essentially non-existent.
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Directed evolution of phosphotriesterase for detoxification of the nerve agent VXGhanem, Eman Mohamed 30 October 2006 (has links)
Phosphotriesterase (PTE) isolated from the soil bacterium Flavobacterium sp. is
a member of the amidohydrolase superfamily. PTE catalyzes the hydrolysis of a broad
spectrum of organophosphate triesters including the insecticide paraoxon, and the
chemical warfare agents; GF, sarin, and soman. In addition, PTE has been shown to
catalytically hydrolyze the lethal nerve agent, VX. However, the rate of VX hydrolysis
is significantly slower. PTE was subjected to directed evolution studies to identify
variants with enhanced activity towards VX hydrolysis. First generation libraries
targeted amino acid residues in the substrate binding site. The H254A mutation
displayed a 4-fold enhancement in kcat and a 2-fold enhancement in kcat/Km over wild
type PTE. The double mutant H254Q/H257F was isolated from the second generation
libraries and displayed a 10-fold enhancement in kcat and a 3-fold enhancement in
kcat/Km. In addition, H254Q/H257F displayed a 9-fold enhancement in kcat/Km for the
hydrolysis of the VX analog, demeton-S.
An in vivo selection approach utilizing organophosphate triesters as the sole
phosphorus source is discussed. The selection is based on co-expressing PTE with the
phosphodiesterase (GpdQ) from E. aerogenes. Substrate specificity of GpdQ was investigated using a small library of structurally diverse organophosphate diesters and
phosphonate monoesters. Results obtained from the in vivo growth assays showed that
GpdQ enabled E. coli to utilize various organophosphate diesters and phosphonate
monoesters as the sole phosphorus source. Cells co-expressing PTE and GpdQ were
tested for their ability to utilize two different organophosphate triesters as the sole
phosphorus source. The results from this experiment indicate that the growth rate is
limited by the phosphotriesterase activity.
Protein translocation to the periplasm was proven advantageous for in vivo
selection since it overcomes the limitation of intercellular delivery of the substrate of
interest. Translocation of PTE to the periplasmic space of E. coli was examined. Two
signal peptides were tested; the native leader peptide from Flavobacterium sp. and the
signal sequence of alkaline phosphatase. The results obtained from cellular fractionation
indicated that neither signal peptides were able to translocate PTE to the periplasm and
that the protein remained in the cytoplasm.
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Implementation plan for self-directed work teams a review of the Implementation Plan for Self-Directed Work Teams for Marconi Communications, Milwaukee, WI /Roberts, Erica. January 2002 (has links)
Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2002. / Field problem. SUPPLEMENTARY BINDER STORED IN ARCHIVES. Includes bibliographical references.
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