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  • 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.
201

Bohr model and dimensional scaling analysis of atoms and molecules

Urtekin, Kerim 25 April 2007 (has links)
It is generally believed that the old quantum theory, as presented by Niels Bohr in 1913, fails when applied to many-electron systems, such as molecules, and nonhydrogenic atoms. It is the central theme of this dissertation to display with examples and applications the implementation of a simple and successful extension of Bohr’s planetary model of the hydrogenic atom, which has recently been developed by an atomic and molecular theory group from Texas A&M University. This ”extended” Bohr model, which can be derived from quantum mechanics using the well-known dimentional scaling technique is used to yield potential energy curves of H2 and several more complicated molecules, such as LiH, Li2, BeH, He2 and H3, with accuracies strikingly comparable to those obtained from the more lengthy and rigorous ”ab initio” computations, and the added advantage that it provides a rather insightful and pictorial description of how electrons behave to form chemical bonds, a theme not central to ”ab initio” quantum chemistry. Further investigation directed to CH, and the four-atom system H4 (with both linear and square configurations ), via the interpolated Bohr model, and the constrained Bohr model (with an effective potential), respectively, is reported. The extended model is also used to calculate correlation energies. The model is readily applicable to the study of molecular species in the presence of strong magnetic fields, as is the case in the vicinities of white dwarfs and neutron stars. We find that magnetic field increases the binding energy and decreases the bond length. Finally, an elaborative review of doubly coupled quantum dots for a derivation of the electron exchange energy, a straightforward application of Heitler-London method of quantum molecular chemistry, concludes the dissertation. The highlights of the research are (1) a bridging together of the pre- and post quantum mechanical descriptions of the chemical bond (Bohr-Sommerfeld vs Heisenberg- Schr¨odinger), and (2) the reporting of the appearance of new bound states of H2 in the presence of very strong magnetic fields. The new states emerge above the critical value of 5 × 107 G, and hence cannot be obtained perturbatively.
202

Three-dimensional fluvial-deltaic sequence stratigraphy Pliocene-Recent Muda Formation, Belida Field, West Natuna Basin, Indonesia

Darmadi, Yan 25 April 2007 (has links)
The Pliocene-Recent Muda formation is essentially undeformed in the West Natuna Basin, and excellent resolution of this interval on three-dimensional seismic data in Belida Field allows detailed interpretation of component fluvial-deltaic systems. Detailed interpretation of seismic time slice and seismic sections along with seismic facies analysis, horizon mapping, and extraction of seismic attributes provide the basis to construct a sequence stratigraphic framework and determine patterns for sediment dispersal and accumulation. The Muda interval contains five third-order sequences, with depositional environments confined to the shelf and consisting mainly of fluvial elements. Sequence boundaries (SB) apparently result from major sea level falls, since there was no tectonic uplift and the field underwent only regional slow subsidence during sedimentation of the study interval. Sea level fluctuation also caused changes in fluvial patterns. Analysis of changing channel patterns indicates that major systems tracts relate to specific channel patterns. The Lowstand Systems Tract (LST) is generally dominated by larger channel dimensions and low sinuosity channel patterns. The Transgressive Systems Tract (TST) typically contains relatively smaller channels with high sinuosity. Channels in the Highstand Systems Tract (HST) generally show moderate sinuosity channels and are intermediate in size, larger than TST channels but smaller than LST channels. Crossplots of stratigraphic position and channel morphology indicate that within the transition from LST-TST, channel dimensions (width and thickness) generally decrease and channel sinuosity generally increases. High sinuosity, meandering and anastomosing channels are generally found near the maximum flooding surface. Low sinuosity channels occur within the HST-SB-LST succession, with the exception of higher sinuosity meandering channels evolving inside valleys. Larger, lower sinuosity channels result from high gradient and high discharge associated with stream piracy. Smaller, high-sinuosity channels result from low gradient and small discharge. Extraction of seismic attributes such as RMS Amplitude and Average Reflection Strength show these depositional features in greater detail. In the Belida Field area, lowstand channels were found to comprise the greatest volume of sandstone bodies. Seismic delineation of the distribution and morphology of these channel systems provides critical input for reservoir modeling and volumetric analysis.
203

The effect of of clerodane diterpenoid 16-hydroxycleroda-3,13-dien-15,16-olide on colorectal cancer cell lines

Chen, Chiu-Roung 15 July 2008 (has links)
Polyalthia longifolia is a lofty evergreen tree found in India and Sri Lanka. Today, P. longifolia var. pendula is in large-scale cultivation in south Taiwan as a landscape plant. A new compound, clerodane diterpenoid 16-hydroxycleroda-3,13-dien-15, 16 -olide¡]CD¡^, was isolated from the bark of Polyalthia longifolia var. pendula. The compound was shown with cell growth inhibitory property at first screen in KMU¡]Kaohsiung Medical University¡^. In our study, antiproliferative activity of CD on human colorectal adenocarcinoma cells¡]HT29 and HCT116¡^were tested and the inhibitory concertration of 50¢Mcell viability¡]IC50¡^is 5 £gg/ml¡]HCT116¡^ and 10 £gg/ml¡]HT29¡^determined by MTT(3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. The caspase 3 and PARP cleavage experiment results indicated that CD induced apoptosis is dose dependent manner. We found that CD induced sub-G1 accumulation and reactive oxygen species(ROS) release by flow cytometry analysis. Pretreatment of N-Acetyl-L-cystine(NAC), an antioxidant agent, can reverse the anti-proliferation effect by CD. We found that CD induced loss of mitochondria membrane potentiol¡]£G£Zm¡^. We also analysis differentially expressed proteins by 2-D electrophoresis and find drug response proteins, e.g. HSP10, Profilin-1, Peroxindoxin-1. RT-PCR and western blot was performed to confirm the protein expression changes. It is interesting to reveal the role of these proteins in the colorectal cancinogenesis and anti-tumor drug response.
204

Numerical study for a micro-PEMFC

Lin, Kuan-Wen 21 August 2008 (has links)
A three dimensional numerical model for a micro proton exchange membrane fuel cell was developed to simulate the concentration distribution of the fuel gas, and analyze the flow field and current field in the fuel cell. Finite control volume scheme with SIMPLEC algorithm was employed in the numerical method. Various operating conditions on the performance of the fuel cell were studied. It was shown that the concentration of oxygen at the cathode can strongly influence the cell performance. Increase the operating temperature and the pressure of the inlet gas can improve the performance of the fuel cell.
205

Analysis of Sp1 associated transcription regulatory factors bound on TSG101 promoter by DAPA and two dimensional gel electrophoresis

LIN, I-Ju 25 August 2008 (has links)
TSG101 is a tumor susceptibility gene exhibits multiple biological functions, including the regulation of vesicular trafficking, transcription, cellular growth and differentiation. The intracellular steady-state level of TSG101 was shown to under stringent control in a narrow range. Either deprivation or overexpression of mouse tsg101 in NIH3T3 cells leads to neoplastic transformation and subsequent tumorigenic potential of the transformed cells. However, the detail mechanism for regulation of TSG101 gene promoter activity is not clear. Our results indicated TSG101 is a housekeeping gene and contains a TATA-less and Sp1 binding site promoter. Here, we demonstrate in vivo binding of Sp1 transcription factor on TSG101 promoter region by chromatin immunoprecipitation(ChIP). In addition, Sp1-associated transcription regulators were purified using DNA affinity precipitation assay (DAPA) method and subjected to two-dimensional gel electrophoresis and the subsequent MALDI-TOF analysis. Our results verify the biding of Sp1 transcription on the DAPA probe containing wildtype but not the mutant Sp1 biding sequence by subsequent western blotting. Our MALDI-TOF analysis of protein spots from two-dimensional gel did not reveal the binding of Sp1 protein, instead the identified a number of cellular proteins, such as U5 small nuclear RNP¡BATP-dependent DNA helicase 2 and actin of unknown significance.
206

Spacecraft pose estimation via a cascading genetic algorithm /

Obsniuk, Mark. January 2006 (has links)
Thesis (M.Sc.)--York University, 2006. Graduate Programme in Computer Science. / Typescript. Includes bibliographical references (leaves 157-162). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29596
207

Improvement of the camera calibration through the use of machine learning techniques

Nichols, Scott A., January 2001 (has links) (PDF)
Thesis (M.S.)--University of Florida, 2001. / Title from first page of PDF file. Document formatted into pages; contains vii, 45 p.; also contains graphics. Vita. Includes bibliographical references (p. 43-44).
208

Theoretical study of dynamic intensity fluctuations in mesoscopic 1D and Quasi-1D systems /

Lu, Danyong. January 2009 (has links)
Includes bibliographical references (p. 58-63).
209

Experimental and theoretical investigation of optical nonlinearity in one-dimensional photonic crystal with central defect mode /

Wong, Tsz Chun. January 2009 (has links)
Includes bibliographical references (p. 74-79).
210

[Pi]-line reconstruction formulas in computed tomography /

Hass, Ryan Andrew. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 115-117). Also available on the World Wide Web.

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