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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.
171

Development and implementation of a FT-ICR mass spectrometer for the investigation of ion conformations of peptide sequence isomers containing basic amino acid residues by gas-phase hydrogen/deuterium exchange

Marini, Joseph Thomas 30 September 2004 (has links)
The gas-phase hydrogen/deuterium (H/D) exchange of protonated di- and tripeptides containing a basic amino acid residue has been studied with a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Bimolecular reactions are monitored as a function of time providing exchange efficiencies and temporal distributions for the peptide ions. Results from these experiments indicated that position of the basic residue within the peptide (i.e. N-terminal, internal, or C-terminal) influences gas-phase H/D exchange, suggesting unique peptide ion conformations. The FT-ICR mass spectrometer employed for these gas-phase H/D exchange studies was modified from its original design. Instrument modifications include development of an internal matrix assisted laser desorption ionization (MALDI) source for peptide protonation. In addition, a two-section cell was utilized, allowing control of ion motion and factors affecting gas-phase ion molecule reactions. Systems investigated in these gas-phase H/D exchange studies are peptides containing the same amino acid residues but different sequences. These sequence isomers display dissimilar reaction efficiencies and temporal distributions for deuterium incorporation depending on the primary structure of the peptide ion. Specifically, [M+H]+ peptide ions containing a N-terminal basic residue demonstrate unique H/D exchange behavior when compared to their internal and C-terminal counterparts. These differences are attributed to dissimilar intramolecular bridging interactions involved with inductive stabilization of the charge site. Gas-phase H/D exchange of peptide sequence isomers was also probed with various deuterium reagents. Findings suggest that different reagents also influence H/D exchange reaction rate efficiencies and temporal distributions. These dissimilarities are ascribed to relative gas-phase basicity and proposed mechanistic exchange differences for the deuterium reagents.
172

Molecular and isotopic demonstration of the processing of aquatic products in northern European prehistoric pottery.

Heron, Carl P., Anderson, E., Craig, Ollie E., Forster, S. H., Stern, Ben 06 July 2009 (has links)
A number of charred surface residues, adhering to ceramic containers, were obtained from various coastal and inland sites in north-west Europe dating from the sixth to the fourth millennium cal bc. In order to investigate the use of these vessels and in particular to identify any marine products, the residues were subjected to carbon and nitrogen stable isotope analysis. Variation in carbon isotope ratios between different samples indicated that some vessels may have been used to process marine products. This analysis was corroborated by specific identification of aquatic products following structural and isotopic characterization of lipids extracted from selected samples.
173

On Amoebas and Multidimensional Residues

Lundqvist, Johannes January 2012 (has links)
This thesis consists of four papers and an introduction.  In Paper I we calculate the second order derivatives of the Ronkin function of an affine polynomial in three variables. This gives an expression for the real Monge-Ampére measure associated to the hyperplane amoeba. The measure is expressed in terms of complete elliptic integrals and hypergeometric functions.  In Paper II and III we prove that a certain semi-explicit cohomological residue associated to a Cohen-Macaulay ideal or more generally an ideal of pure dimension, respectively, is annihilated precisely by the given ideal. This is a generalization of the local duality principle for the Grothendieck residue and the cohomological residue of Passare. These results follow from residue calculus, due to Andersson and Wulcan, but the point here is that our proof is more elementary. In particular, it does not rely on the desingularization theorem of Hironaka. In Paper IV we prove a global uniform Artin-Rees lemma for sections of ample line bundles over smooth projective varieties. We also prove an Artin-Rees lemma for the polynomial ring with uniform degree bounds. The proofs are based on multidimensional residue calculus. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4. Manuscript.</p>
174

A library approach to single site and combinatorial residue contributions to dimerization of BNIP3-like transmembrane domains

January 2012 (has links)
A poly-leucine transmembrane domain library was randomized at positions corresponding to contact surfaces for a right-handed crossing of two helices to determine the significance of small residues, GxxxG motifs, and hydrogen bonding residues in driving helix-helix interactions within membranes. About 10000 sequences, which include the interfaces of tightly interacting biological transmembrane domains, were subjected to increasing selection strength in the membrane interaction assay TOXCAT and surviving clones were sequenced to identify single site and pairwise amino acid trends. Statistical analysis identified a central glycine to be essential to strong dimerization. The next strongest statistical preference was for a phenylalanine three positions before the key glycine. Secondary to these residues, polar histidine and asparagine residues are also favored in strongly dimerizing sequences, but not to the exclusion of hydrophobic leucine and isoleucine. The analysis identifies novel pairwise combinations that contribute to or are excluded from strong dimerization, the most striking of which is that the biologically important GxxxGxxxG/A pattern is under-represented in the most strongly associating BNIP3-like transmembrane dimers. The variety of residue combinations that support strong dimerization indicates that not only key 'motif' residues, but also the residues that flank them, are important for strong dimerization. Because favorable pairwise combinations of flanking residues occur between both proximal positions and residues separated by two or more turns of helix, the complexity of how sequence context influences motif-driven dimerization is very high.
175

Influence of Transplanter Modification and Previous Crop on the Production of No-Till Dark Tobacco

Penick, William Frazier 01 May 2013 (has links)
Dark tobacco (Nicotiana tabacum L.) has historically been produced usingconventional tillage practices. Soil is cultivated multiple times throughout a growing season leading to an increased incidence of soil erosion. No-till systems have been growing in popularity with the advent of new technology that has enabled the practice to be performed effectively and efficiently. With the recent expansion of no-till practices throughout the agricultural community, many crops have had success in producing comparable yields while reducing input costs and saving soil resources. For this experiment, a traditional tobacco transplanter was modified for use in a no-till environment. All modifications were fabricated without using specialty tools and made possible to be removed if desired or necessary. Frame extensions were designed and built to accommodate row cleaners and coulters. Tillage shanks were also added to aid in optimal furrow formation. Double-disc opening shoes replaced the original round point shoes and the curved edges of the rear drive wheels were removed, creating a flat surface to increase soil contact. Experimental no-till plots in fescue sod and soybean chaff residues were conducted alongside conventional tillage plots at the Western Kentucky University Agricultural Research and Education Complex in summer 2011. Five treatments, one conventionally tilled (Conv) and four no-till, were replicated three times within a randomized complete block design and used to determine the efficacy of transplanter modifications (consistency of depth, furrow closure, observed plant damage), survival of the transplants, and the amount of residue displacement. The four no-till treatments utilized different combinations including: coulter, row cleaner and shank (CRS), row cleaner and shank (RS), coulter and shank (CS), and shank only (S). These treatments demonstrated the functionality of each combination in comparison to conventional treatments. No treatment performed equally well in both residue locations. Plots in fescue residue utilizing a combination of coulter, row cleaner, shank (CRS), exhibited the lowest amount of root exposure, highest survival rate, and comparable cured weight when compared to conventionally tilled treatments. In soybean residue plots, the treatment operating with row cleaners and shanks (RS) had equivalent amounts of furrow closure to conventionally tilled plots. Pairing specific modification combinations with previous crop residue can provide furrow closure, transplant survival, and cured yield equivalent to conventionally tilled dark tobacco.
176

Mapping energy crop cultivation and identifying motivational factors among Swedish farmers

Ostwald, Madelene, Jonsson, Anna, Wibeck, Victoria, Asplund, Therese January 2013 (has links)
Based on a meta-study, the paper describes the existing options, areal extents, and Swedish farmers' conditions for energy crop production promoted by the governments to mitigate and adapt to climate change. The drivers of and barriers to cultivating various energy crops are described in terms of a variety of motivational factors. The approach used peer-reviewed and gray literature using three Internet sources. Questions addressed include the energy crops available to Swedish farmers and how well established they are in terms of areal extent. What drivers of and barriers to growing energy crops do farmers perceive? How do various motivational factors for these drivers and barriers correspond to the adoption of certain energy crops? The results indicate that 13 energy-related crops are available, of which straw (a residue), oil crops, and wheat are the most extensively produced in terms of cultivated area. Results confirm earlier research findings that converting from annual to perennial crops and from traditional crops or production systems to new ones are important barriers. Economic motivations for changing production systems are strong, but factors such as values (e.g., esthetic), knowledge (e.g., habits and knowledge of production methods), and legal conditions (e.g., cultivation licenses) are crucial for the change to energy crops. Finally, there are knowledge gaps in the literature as to why farmers decide to keep or change a production system. Since the Swedish government and the EU intend to encourage farmers to expand their energy crop production, this knowledge of such motivational factors should be enhanced. / Ett konkurrenskraftigt jordbruk – kommunikation kring klimatförändring och nya möjligheter (K3), Stiftelsen Lantbruksforskning
177

Time and statistical information utilization in high efficiency sub-micron CMOS successive approximation analog to digital converters

Guerber, Jon 07 January 2014 (has links)
In an industrial and consumer electronic marketplace that is increasingly demanding greater real-world interactivity in portable and distributed devices, analog to digital converter efficiency and performance is being carefully examined. The successive approximation (SAR) analog to digital converter (ADC) architecture has become popular for its high efficiency at mid-speed and resolution requirements. This is due to the one core single bit quantizer, lack of residue amplification, and large digital domain processing allowing for easy process scaling. This work examines the traditional binary capacitive SAR ADC time and statistical information and proposes new structures that optimize ADC performance. The Ternary SAR (TSAR) uses the quantizer delay information to enhance accuracy, speed and power consumption of the overall SAR while providing multi-level redundancy. The early reset merged capacitor switching SAR (EMCS) identifies lost information in the SAR subtraction and optimizes a full binary quanitzer structure for a Ternary MCS DAC. Residue Shaping is demonstrated in SAR and pipeline configurations to allow for an extra bit of signal to noise quantization ratio (SQNR) due to multi-level redundancy. The feedback initialized ternary SAR (FITSAR) is proposed which splits a TSAR into separate binary and ternary sub-ADC structures for speed and power benefits with an inter-stage encoding that not only maintains residue shaping across the binary SAR, but allows for nearly optimally minimal energy consumption for capacitive ternary DACs. Finally, the ternary SAR ideas are applied to R2R DACs to reduce power consumption. These ideas are tested both in simulation and with prototype results. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Jan. 7, 2013 - Jan. 7, 2014
178

Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry

Timmons, Christopher L. 14 December 2004 (has links)
During fabrication of integrated circuits, fluorocarbon plasma etching is used to pattern dielectric layers. As a byproduct of the process, a fluorocarbon residue is deposited on exposed surfaces and must be removed for subsequent processing. Conventional fluorocarbon cleaning processes typically include at least one plasma or liquid treatment that is oxidative in nature. Oxidative chemistries, however, cause material degradation to next generation low-dielectric constant (low-k) materials that are currently being implemented into fabrication processes. This work addresses the need for alternative fluorocarbon-residue removal chemistries that are compatible with next generation low-k materials. Radical anion chemistries are known for their ability to defluorinate fluorocarbon materials by a reductive mechanism. Naphthalene radical anion solutions, generated using sodium metal, are used to establish cleaning effectiveness with planar model residue films. The penetration rate of the defluorination reaction into model fluorocarbon film residues is measured and modeled. Because sodium is incompatible with integrated circuit processing, naphthalene radical anions are alternatively generated using electrochemical techniques. Using electrochemically-generated radical anions, residue removal from industrially patterned etch structures is used to evaluate the process cleaning efficiency. Optimization of the radical anion concentration and exposure time is important for effective residue removal. The efficiency of removal also depends on the feature spacing and the electrochemical solvent chosen. The synergistic combination of radical anion defluorination and wetting or swelling of the residue by the solvent is necessary for complete removal. In order to understand the interaction between the solvent and the residue, the surface and interfacial energy are determined using an Owens/Wendt analysis. These studies reveal chemical similarities between specific solvents and the model residue films. This approach can also be used to predict residue or film swelling by interaction with chemically similar solvents.
179

Generalized minimal polynomial over finite field and its application in coding theory

Jen, Tzu-Wei 27 July 2011 (has links)
In 2010, Prof. Chang and Prof. Lee applied Lagrange interpolation formula to decode a class of binary cyclic codes, but they did not provide an effective way to calculate the Lagrange interpolation formula. In this thesis, we use the least common multiple of polynomials to compute it effectively. Let E be an extension field of degree m over F = F_p and £] be a primitive nth root of unity in E. For a nonzero element r in E, the minimal polynomial of r over F is denoted by m_r(x). Then, let Min (r, F) denote the least common multiple of m_r£]^i(x) for i = 0, 1,..., n-1 and be called the generalized minimal polynomial of over F. For any binary quadratic residue code mentioned in this thesis, the set of all its correctable error patterns can be partitioned into root sets of some generalized minimal polynomials over F. Based on this idea, we can develop an effective method to calculate the Lagrange interpolation formula.
180

Chip Seals for Asphalt Concrete Pavements: A Proposed Emulsion Residue Specification and Existing Pavement Texture Evaluation

Hoyt, Denise 2012 May 1900 (has links)
Chip seals are a pavement surface treatment used for maintaining asphalt concrete pavements. National Cooperative Highway Research Program (NCHRP) Project 14-17 was performed to produce a national Chip Seal Manual which would consolidate the best chip seal engineering practices. A subcontract to NCHRP Project 14-17 performed at Texas A&M University was the basis for this thesis. It included the following tasks: investigation of a testing and grading system for grading asphalt binder residues from chip seal emulsions; and investigation of texture measurement methods for assessing existing pavement macrotexture before a chip seal is placed. The performance graded (PG) asphalt binder specification, which was developed to characterize asphalt binder properties related to the performance of hot mix asphalt concrete in pavements, cannot be directly applied to asphalt binders or emulsion residues for use in chip seals. Therefore, the surface performance graded (SPG) specification was developed using the same equipment as the PG system but with some procedural modifications and different limiting values for the test parameters. NCHRP Project 14-17 utilized the PG and SPG systems to grade base asphalt binders and recovered emulsion residues. Two emulsion residue recovery methods were compared: hot oven evaporation with nitrogen blanket and stirred can with nitrogen purge. The PG and SPG grades were found to be similar for the two emulsion residue recovery methods but slightly different from the base asphalt binder. A strawman specification for emulsion residues in chip seals was recommended for use with the stirred can recovery method. In chip seal construction, macrotexture of the existing pavement affects the rate at which chip seal emulsion must be applied. In this project, existing pavement macrotextures were measured at three chip seal projects immediately before construction using both the sand patch test and the circular track meter, CT Meter. The CT Meter was found to quickly and effectively measure pavement macrotexture. The CT Meter measurements correlated well with the sand patch test measurements. Finally, this project investigated the utility of measuring pavement macrotexture in the laboratory using the aggregate imaging system (AIMS) on pavement cores and on small samples cut from fabricated slabs. Statistical analyses showed good correlation between the mean profile depth, MPD, calculated from AIMS measurements on pavement cores and small samples, based on analysis using 50 mm (2 inch) segment lengths, and the MPD measured on the pavement or on the large fabricated slabs with the CTMeter. These results supported the use of AIMS to measure pavement macrotexture using small samples in the laboratory.

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