This research examines and compares the distributions of archaeological sites and materials in order to investigate native settlement patterns and resources use throughout 12,000 years of prehistory and protohistoric time within the Apalachicola/Lower Chattahoochee River valley of northwest Florida, southwest Georgia, and southeast Alabama. Geographic Information Systems (GIS) are used to map the distributions of sites from different time periods and to explore their relation to various environmental characteristics that are now available in digital format. I employ tools now available in GIS to examine several longstanding research questions and expand upon archaeological interpretations within this region, where the University of South Florida (USF) has an ongoing research program. The results of this work illustrate change through time and space as cultures begin to adapt to post-Pleistocene ecological change, develop food production and complex societies, and react to the appearance of European groups.

This study is a paroemiological consideration of Brennu-Njáls saga in which a set of repeated scenes that include or are associated with repeated proverbial utterances are examined in order to draw conclusions as to the compositional role of proverbs and paroemial material in the saga. The study begins with a brief discussion of proverb scholarship in which the intertextual nature of the proverb genre is established, moving into a discussion of certain important scenes in the saga narrative and their association with repeated proverbial utterances that exemplify and encapsulate the saga’s overarching thematic concerns. It is shown that the proverb, as a compositional device in the saga, serves as the basis for repeated scenes that illustrate or act out the proverbs with which they are associated. Proverbs can be seen to indicate the ethics and motivations of associated characters as well as to provide an interpretive framework by which such proverb-scenes and the greater saga narrative could be understood by both the contemporary and modern saga audience. Furthermore, it is shown that the composer of Njála made use of the proverbial form to communicate both ostensibly traditional pre-Christian wisdom regarding the nature of Icelandic feud and social relations as well as later wisdom derived from the Christian scriptural tradition, indicating that the proverb as a compositional device was integral to the assimilation of Christian teachings into the literary depiction of Iceland’s pagan past. The paroemial cognitive patterning of the saga audience allowed for the extensive use of the proverbial form in the comparison of Icelandic pre-Christian and Christian social ethics, and the proverbial form itself can be seen as a prominent compositional device in Njála.

Due to aggressive scaling in semiconductor industry, the traditional optical lithography system is facing great challenges printing 32nm and below circuit layouts. Various promising nanolithography techniques have been developed as alternative solutions for patterning sub-32nm feature size. This dissertation studies physical design related optimization problem for these emerging methodologies, mainly focusing on double patterning and electronic beam lithography. Double Patterning Lithography (DPL) decomposes a single layout into two masks, and patterns the chip in two exposure steps. As a benefit, the pitch size is doubled, which enhances the resolution. However, the decomposition process is not a trivial task. Conflict and stitch are its two main manufacturing challenges. First of all, a post-routing layout decomposer has been developed to perform simultaneous conflict and stitch minimization, making use of the integer linear programming and efficient graph reduction techniques. Compared to the previous work which optimizes conflict and stitch separately, the proposed method produces significantly better result. Redundant via insertion, another key yield improvement technique, may increase the complexity in DPL-compliance. It could easily introduce unmanufacturable conflict, while not carefully planned and inserted. Two algo- rithms have been developed to take care of this redundant via DPL-compliance problem in the design side. While design itself is not DPL-friendly, post-routing decomposition may not achieve satisfactory solution quality. An efficient framework of WISDOM has been further proposed to perform wire spreading for better conflict and stitch elimination. The solution quality has been improved in great extent, with a little extra layout perturbations. As another promising solution for sub-22nm, Electronic Beam Lithography (EBL) is a maskless technology which shoots desired patterns directly into a silicon wafer, with charged particle beam. EBL overcomes the diffraction limit of light in current optical lithography system, however, the low throughput becomes its key technical hurdle. The last work of my dissertation formulates and investigates a bin-packing problem for reducing the processing time of EBL. / text

During embryonic vasculogenesis, endothelial cells form in the mesoderm , assemble into cord-like structures and then undergo tube formation. Previous studies have shown that signaling by members of the hedgehog family of secreted growth factors is essential for normal development of embryonic blood vessels. Embryos lacking hedgehog function show the presence of abundant endothelial cells but the cells fail to assemble into vascular cords and lumenized endothelial tubes do not form. At present it is not known whether active hedgehog signaling is required for both cord and tube formation or only for the initial step. To address this question, we have used small molecule inhibitors and agonists to the alter activity of the hedgehog signaling pathway in the chick embryo. If development is allowed to proceed until endothelial cells of the future dorsal aortae have assembled into cords, subsequent inhibition of hedgehog signaling, using cyclopamine, does not prevent aortal cells from forming endothelial tubes, however, it does lead to a reduction in cross sectional area of the aorta and to a loss of density of the adjacent vascular plexus. In contrast, activation of the hedgehog pathway with SAG leads to formation of enlarged aortae and increased density of the plexus. Very little, if any, of the observed effects are due to differences in number of endothelial cells in the treated embryos. Examination of endothelial cells during vascular plexus formation shows that inhibition of hedgehog signaling with cyclopamine inhibits formation of filopodia while treatment with SAG increases the number of filopodial extensions. These studies show that hedgehog signaling levels must be tightly regulated for normal vascular patterning to be achieved.

Gastrulation is one of the most critical events of embryogenesis, generating the three primary germ layers (definitive endoderm, mesoderm, and ectoderm) and establishing the embryonic body plan. The definitive endoderm, which generates the lungs, liver, pancreas, and digestive tract, has become a tissue of particular interest in recent years. Understanding definitive endoderm formation and patterning will greatly aid progress in the in vitro differentiation of embryonic stem cells to definitive endoderm for use in treatment of diseases such as diabetes and hepatitis as an alternative for whole organ replacement. Gene targeting studies have demonstrated a critical role for the Nodal signaling pathway and the forkhead transcription factors Foxh1 and Foxa2 in specification of a group of cells referred to as the anterior primitive streak (APS). However, the transcriptional targets of Foxh1 and/or Foxa2 other than Nodal that regulate specification of this group of cells are currently unknown. Fate mapping and lineage tracing experiments have shown the APS to be the source of the definitive endoderm. However, many questions regarding specification and patterning of the definitive endoderm remain. The study of this tissue has been hampered by the lack of genetic markers specific for the definitive endoderm as many of the current markers, including Cerl, Foxa2, and Sox17, are also expressed in the visceral endoderm, an extraembryonic tissue. To further investigate the role of Foxh1 in specification of the anterior primitive streak and to address the lack of genetic markers for the definitive endoderm we performed expression profiling on post-implantation mouse embryos using Affymetrix™ GeneChips®. From this analysis we identified and characterized a novel marker of the mouse definitive endoderm. Examination of this, and other, novel endoderm markers in Foxh1 and Foxa2 deficient mouse embryos revealed that contrary to current models of definitive endoderm formation, we find some definitive endoderm is formed in these mutants. Specifically, specification of the midgut and hindgut definitive endoderm is largely unaffected, while foregut formation is severely affected. These results suggest that the formation of the midgut and hindgut definitive endoderm populations is independent of the anterior primitive streak and separate from the foregut definitive endoderm. This represents a major insight into the mechanisms regulating endoderm formation and patterning.

Steps on surfaces have long been explored for their own sake, and exploited as growth mediators. However, another type of linear surface defect - the domain boundary - has been largely neglected. Here we introduce domain boundaries of the 5x5 dimer-adatom-stacking fault reconstruction, explore their properties and demonstrate that they too can be used to mediate growth in a useful manner. When a thin layer of Ge is grown on Si(111) lattice strain induces the overlayer to reconstruct as Ge5x5. Using solid phase epitaxy, many domains of 5x5 can be grown. The domain interiors have excellent order, and with careful annealing, the boundaries that separate them are straight and uniform. Well-ordered boundaries propagate along the two high symmetry directions <1 -1> or <1 1> and are called A-type or B-type respectively. Boundaries of the second type are unique to Ge5x5. Registration with the substrate restricts the misfit between domains to discrete possibilities which are labeled according to a modified version of the system used for domain boundaries of Si(111)7x7. The distribution of observed boundary types is strongly peaked and reflects the relative energies of boundaries of different character. The expanded labeling scheme can be used to sketch the kinetic processes which lead to the distribution peaks. The dominant boundary by far is the one known as B[-2 2], which accounts for almost half of all observed boundaries. The atomic structure for this type of boundary has been established as a truncated 7x7 unit cell. Thus, these boundaries are linear arrays of quasi-7x7 embedded in a sea of 5x5. On the Si(111)7x7 surface the Group 13 elements, when deposited at sub-ML coverages and low temperatures, form magic clusters. The perfect uniformity and precise registration that earns them the moniker ‘magic’ make these clusters unusual among self-organized atomic scale objects. The clusters that form on 5x5 lack the uniformity of their counterparts on 7x7. However, with many domains, deposited In or Ga segregate to the quasi-7x7 B[-2 2] boundaries and there form magic clusters. The boundary thus acts as a template for growing straight lines of precisely spaced, atomically identical, nanoscale clusters. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-07-29 08:50:16.874

No description available.

In this work, the modification of conducting substrates with thin (nanometer thick) aryl films via reaction with aryldiazonium salts was investigated. Two methods were used: modification by electro-reduction of the aryldiazonium salts and modification by spontaneous reaction of aryldiazonium the salts with the surface at open circuit potential. The majority of the studies were undertaken using p-nitrobenenze diazonium salt, which gives electro-active nitrophenyl (NP) films at the surface that can be detected and characterized by cyclic voltammetry. Films prepared spontaneously on carbon and gold electrodes at open circuit potential were characterized by electrochemistry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. At both carbon and gold, spontaneous modification proceeds via electron transfer from the surface to the diazonium salt.Furthermore, on both types of surface, spontaneously prepared NP films were found to be loosely packed multilayers of less than 5 nm in thickness. The spontaneous reaction was utilized for the patterning of carbon, gold, silicon and copper surfaces by microcontact printing (μCP) with diazonium salts. The presence of spontaneously formed films upon printing was confirmed by cyclic voltammetry and AFM. The films were demonstrated to be useful for the tethering of further molecules to the surface. Patterns prepared by μCP were imaged using scanning electron microscopy (SEM) and condensation figures. The preparation of two-component systems, with different chemical functionalities attached to different, well-defined, regions of the surface, was demonstrated. The optimization of the long term activity of glucose oxidase hydrogels by covalent attachment of the hydrogels to modified carbon electrodes was investigated. Covalent attachment was demonstrated, but the resulting electrode-hydrogel surfaces did not show long-term activities superior to those for physisorbed hydrogels. It is suggested that the limiting factor for long-term hydrogel activity is not adhesion of the hydrogel to the surface, but degradation of enzymatic activity by H2O2.

Chapter 1 provides an overview of the current literature regarding molecular level modification of conducting surfaces. The modification of carbon surfaces are discussed, with particular attention being given to the use of aryldiazonium salt compounds. Patterning of molecular layers using aryldiazonium salts and arylazides is detailed. The objectives of the project are outlined. Chapter 2 contains the general experimental methods, instrumentation, chemicals, and materials used throughout this thesis. Chapter 3 details the development of two technical methods: a heat treatment method for regenerating diazonium-modified or deactivated pyrolysed photoresist film electrodes, and a method for preparing evaporated carbon film electrodes. Although regeneration of the evaporated carbon surfaces was unsuccessful, the surfaces exhibited good electrochemical properties and are useful substrates for studying diazonium-derived films. Chapter 4 reports the covalent modification of carbon, gold, and indium tin oxide surfaces with thin porphyrin films via the electrochemical reduction of porphyrin aryldiazonium salts. Surface characterisation studies revealed that the films are stably-attached and exhibit well-defined redox and optical properties. Chapter 5 describes the preparation and patterning of organic films on carbon and silicon surfaces using arylazides combined with photolithography. Strategies were investigated to generate continuous mixed films and surfaces presenting patterns of one or two components. For all grafted surfaces, the reactivity of tether species was confirmed by coupling electroactive targets or gold nanoparticles to the tethers, followed by electrochemical analysis or surface microscopy. Chapter 6 details the modification of carbon surfaces with diazonium-derived films via aryltriazenes. Also described in this chapter is the development of microfluidics, for use with aryltriazene and aryldiazonium salt solutions, for generating parallel surface patterns. Chapter 7 concludes and answers to the challenges reported in this study. Future directions are briefly discussed.

Sterols have been identified as major components of membrane lipids that are part of specialized membrane domains necessary for organizing events such as polar protein targeting and signal transduction in plants, fungi and animals. However a common modification of sterols is the addition of sugar moieties via glycosylation abundantly found in plants. An exact physiological role for such diversification of sterols in plants is still unknown. Using reverse genetics and transcriptomics we show that UDP-glucose: sterol glucosyltransferase encoded by UGT80B1 is necessary for correct epidermal patterning in Arabidopsis root. Patterning of hair cells (trichoblasts) and non-hair cells (atrichoblasts) in the epidermis of the Arabidopsis root involves signaling through SCRAMBLED (SCM), a plasma membrane localized LRR-RL kinase. Feedback regulation via the transcriptional regulatory complex containing R2R3-MYB transcription factor WEREWOLF (WER) represses SCM and activates the homeodomain-leucine-zipper protein GLABRA2 (GL2) in atrichoblasts. Evidence suggests symplastic connections between cells, known as plasmodesmata, establish passage ways for single-repeat R3-MYB transcription factors to activate SCM expression in trichoblasts. Mutations in UGT80B1 cause atypical localization patterns of GL2, WER, and SCM in the root epidermis. The ugt80B1 formed fewer trichoblasts in comparison to wild-type. A translational fusion of UGT80B1 to GFP localizes to the ER, plasma membrane and to sites that appear to be plasmodesmata-associated desmotubules. Ultrastructural analysis revealed abnormalities in plasmodesmata formation and morphology in ugt80B1 mutants. Steryl glucoside profiling indicated deficiencies in specific glycosylated sterol compounds in roots. This study identifies UGT80B1 as a novel membrane component that is critical for plasmodesmata morphogenesis and cell-fate determination in the root epidermis. A model is proposed in which UGT80B1 activity provides spatially discreet sterol and steryl glucoside architecture within the plasma membrane to anchor the SCM receptor and within plasmosdesmata to facilitate intercellular movement of R3-MYB regulatory proteins underlying proper differentiation of trichoblasts versus atrichoblasts. Moreover, evidence from reverse genetics, proteomics and live cell imaging point to a actin dependent localization of UGT80B1 at the vesicle rich zone of root hair tip. This localization actively supports root hair elongation via tip growth, possibly by membrane modifications required for vesicle trafficking.