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AFM-Based Nanolithography and Detection of DNA Hybridization Reactions at the NanoscaleLo, Shu-ting 23 July 2007 (has links)
High-resolution lattice periodicity images of a variety of well-defined surfaces, including graphite, mica, and Au(111), validated the good stability of our atomic force microscope (AFM) system. Combining self-assembled monolayer (SAM) and AFM technology, we demonstrated the capabilities of pattern fabrication as well as modification of surface functionality. AFM-based nanolithography operating conditions, such as scan rate, deflection setpoint, and number of scan were studied to obtain the optimized quality of the fabricated patterns. Thiolated-DNA probe molecules could be patterned at a nanometer scale on a gold substrate. However, we found that the surface coverage began to drop notably with the probe length (number of DNA bases). Therefore, the displaced DNA molecules during nanoshaving were reversibly adsorbed, and patterning became unreliable. We were unsuccessful in detecting the subsequent hybridization reactions at these nanopatterns from AFM measurements. To realize the DNA hybridization, further studies on the incubation temperature, probe length and even DNA sequences are required to demonstrate that this AFM-based gene diagnostic method is truly operational.
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Transport and Magnetic Properties of Pr1-xBa2+xCu3O7Hong, I-Po 27 July 2000 (has links)
Since the discovery of cuprate superconductors, PrBa2Cu3O7 (Pr123) has attracted much attention due to its nonsuperconductivity and other anomalies. The very recent reports on superconducting Pr123 instead of putting an end of this issue, virtually stimulate more controversies. One of the proposed explanations for the recently observed superconductivity in Pr123 is that the samples could be Ba-rich Pr123 to investigate this possibility, we prepared Pr1-xBa2+xCu3O7 (x=1~0.3) and Pr1-xCaxBa2Cu3O7 (x=0~0.6) as comparison. X-ray absorption near edge spectroscopy (XANES) indicates an increase in carrier concentration with Ba and Ca doping, which is consistent with resistivity and thermoelectric power(TEP) data. However, carriers are introduced in a peculiar why rather than simply add into CuO2 plane.
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The study and comparison of maize centromeric sequences /Page, Brent January 2000 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 168-176). Also available on the Internet.
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Rekernelisation algorithms in hybrid phylogenies : a thesis submitted in partial fulfilment of the requirements of the degree for Master of Science in Mathematics at the University of Canterbury /Collins, Joshua January 2009 (has links)
Thesis (M. Sc.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (leaves 73-77) and index. Also available via the World Wide Web.
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Affinity bioseparations with smart polymer conjugates containing DNA, streptavidin, and antibody fragments /Fong, Robin B. January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 122-137).
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The study and comparison of maize centromeric sequencesPage, Brent January 2000 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 168-176). Also available on the Internet.
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Analysis of HER2 testing in breast cancerAshok, Mahima. January 2009 (has links)
Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Griffin, Paul; Committee Member: Butera, Robert; Committee Member: Halpern, Michael; Committee Member: Nichols, Richard; Committee Member: Vidakovic, Brani. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Mate choice and hybridization within swordtail fishes (Xiphophorus spp.) and wood warblers (family Parulidae)Willis, Pamela Margaret 04 June 2012 (has links)
Behavioral isolation is an important barrier to gene flow, contributing to the
formation and maintenance of animal species. Nevertheless, hybridization occurs more
commonly than is generally recognized, occurring in over ten percent of animal species
in the wild. Although the genetic consequences of hybridization are of considerable
interest given their evolutionary implications, the reasons that animals choose to mate
with other species are less clear. I apply mate choice theory to the question of
hybridization, using wood warblers (family Parulidae) and swordtail fishes (genus
Xiphophorus) as study systems.
Over half of the 45 species of North American wood warbler have produced
hybrids. Using comparative methods, I address the questions: Do ecological and
demographic factors predict hybridization in this family? Similarly, how do phylogeny,
song similarity, and sympatry with congeners correlate with hybridization? As with North
American wood warblers, behavioral isolation is also considered of primary importance
in isolating sympatric species of swordtail fishes. Two species, X. birchmanni and X.
malinche, hybridize in several locations in the wild. Through experimentation with these
and other Xiphophorus species, I investigate some of the factors that cause female mate
choice to vary, possibly contributing to hybridization. Specifically, I address the
following questions: Do females become less choosy when predation risk is high, or
encounter rates with conspecifics are low? Are female preferences for conspecifics
innate, or can they be modified by experience? And, do female preferences for
conspecifics vary among species, populations, or experiments?
These studies illustrate the utility of treating hybridization as just another possible
outcome of variation in mate choice. I find that warbler hybridization correlates with
ecological and other variables, that female swordtails become more responsive to
heterospecifics when mate choice is costly, and that female preferences for conspecifics
are species- and context-dependent. As animal hybridization can have important
evolutionary consequences, studying the factors that contribute to this variation can
enhance our understanding of the evolutionary process. / text
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Cytogenetic analysis of head and neck cancer by comparative genomic hybridization錢文偉, Chien, Man-wai, Gary. January 2001 (has links)
published_or_final_version / Surgery / Master / Master of Philosophy
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A Biogeographic Perspective of Speciation Among Desert Tortoises in the Genus GopherusEdwards, Taylor Artemus January 2015 (has links)
One of the important contributions genetic studies have made to conservation is the ability to resolve taxonomy and define relationships among populations. However, this can be complicated when species exhibit hybridization. Hybridization can be an important part of the evolutionary process and a critical component in a species ability to adapt to a changing environment. Most hybrid zones are observed at ecotones between two distinct habitats and this may be important in defining the role of hybrid zones in the evolutionary process. I examined hybridization among the three distinct lineages of desert tortoises in the genus Gopherus. An important aspect of this study system is the presence of areas of overlap between divergent lineages of desert tortoise which allowed me to test hypotheses about which forces influence these taxonomic boundaries. Specifically, I tested hypotheses about the contribution of physical vs. ecological segregation and the relative importance of isolation and gene flow in the formation of these disparate desert tortoise lineages. I used mtDNA sequence data and 25 microsatellite loci to perform Bayesian clustering, clinal analyses and habitat suitability modeling to infer population structure and influence of landscape features at each contact zone. In both instances, I observed ecological niche partitioning and limited hybridization at ecotones. I then used mtDNA and four nDNA loci to perform a multi-locus phylogenetic analysis to estimate the species tree among desert tortoise lineages and tested for ancestral admixture with RNA-seq data using demographic inference employed in the software package ∂a∂i. My results validate taxonomic distinction among all three lineages without evidence of ancestral introgression. These data suggest that despite the presence of contemporary hybridization and incomplete reproductive isolation, divergence among these lineages is consistent with species-level differentiation. By clarifying the evolutionary processes that influence the distribution of desert tortoise lineages, this study will directly inform efforts to preserve the evolutionary potential of these threatened species. Ultimately, understanding the evolutionary history of desert tortoises not only clarifies the forces that have driven speciation in this group, but it also contributes to our knowledge of the biogeographic history of the southwestern deserts and how diversity is maintained within them.
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