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Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases

Description: Many activities are comprised of temporally dependent events that must be executed in a specific chronological order. Supportive software applications must preserve these temporal dependencies. Whenever the processing of this type of an application includes transactions submitted to a database that is shared with other such applications, the transaction concurrency control mechanisms within the database must also preserve the temporal dependencies. A basis for preserving temporal dependencies is established by using (within the applications and databases) real-time timestamps to identify and order events and transactions. The use of optimistic approaches to transaction concurrency control can be undesirable in such situations, as they allow incorrect results for database read operations. Although the incorrectness is detected prior to transaction committal and the corresponding transaction(s) restarted, the impact on the application or entity that submitted the transaction can be too costly. Three transaction concurrency control algorithms are proposed in this dissertation. These algorithms are based on timestamp ordering, and are designed to preserve temporal dependencies existing among data-dependent transactions. The algorithms produce execution schedules that are equivalent to temporally ordered serial schedules, where the temporal order is established by the transactions' start times. The algorithms provide this equivalence while supporting currency to the extent out-of-order commits and reads. With respect to the stated concern with optimistic approaches, two of the proposed algorithms are risk-free and return to read operations only committed data-item values. Risk with the third algorithm is greatly reduced by its conservative bias. All three algorithms avoid deadlock while providing risk-free or reduced-risk operation. The performance of the algorithms is determined analytically and with experimentation. Experiments are performed using functional database management system models that implement the proposed algorithms and the well-known Conservative Multiversion Timestamp Ordering algorithm.
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Date: May 2001
Creator: Tuck, Terry W.
Partner: UNT Libraries

Teen ages: Youth market romance in Hollywood teen films of the 1980s and 1990s

Description: This thesis examines the differences between teen romantic comedy films marketed to Generation X teenagers in the 1980s and Generation Y teenagers in the 1990s, focusing on the presentation of gender roles, consumptive behavior, and family. The 1980s films are discussed within the social context of the Reagan era and the conservatism of the New Right. The 1990s films are examined as continuing a conservative sensibility, but they additionally posit consumption as instrumental to achieving an idealized romance. Romantic comedy is traditionally a conservative genre, but these films illustrate female liberation through consumption. The source of difference between the cycles of teen romantic comedy is attributed to the media's attempt to position Generation Y teenagers as ideal consumers.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: May 2001
Creator: Murphy, Caryn E.
Partner: UNT Libraries

A Collapsing Result Using the Axiom of Determinancy and the Theory of Possible Cofinalities

Description: Assuming the axiom of determinacy, we give a new proof of the strong partition relation on ω1. Further, we present a streamlined proof that J<λ+(a) (the ideal of sets which force cof Π α < λ) is generated from J<λ+(a) by adding a singleton. Combining these results with a polarized partition relation on ω1
Date: May 2001
Creator: May, Russell J.
Partner: UNT Libraries

Isolation and analysis of cotton genomic clones encompassing a fatty acid desaturase (FAD2) gene

Description: Polyunsaturated fatty acids are major structural components of plant chloroplast and endoplasmic reticulum membranes. Two fatty acid desaturases (designated FAD2 and FAD3) desaturate 75% of the fatty acids in the endoplasmic reticulum. The w -6 fatty acid desaturase (FAD2) may be responsible for cold acclimation response, since polyunsaturated phospholipids are important in helping maintain plant viability at lowered temperatures. To study regulation of FAD2 gene expression in cotton, a FAD2 gene was isolated from two genomic libraries using an Arabidopsis FAD2 hybridization probe and a cotton FAD2 5¢ -flanking region gene-specific probe, respectively. A cotton FAD2 gene was found to be in two overlapping genomic clones by physical mapping and DNA sequencing. The cloned DNA fragments are identical in size to cotton FAD2 genomic DNA fragments shown by genomic blot hybridization. The cotton FAD2 coding region has 1,155 bp with no introns and would encode a putative polypeptide of 384 amino acids. The cotton FAD2 enzyme has a high identity of 75% with other plant FAD2 enzymes. The enzyme has three histidine-rich motifs that are conserved in all plant membrane desaturases. These histidine boxes may be the iron-binding domains for reduction of oxygen during desaturation. To confirm that this FAD2 enzyme is functional, a plasmid construct containing the cotton FAD2 coding region was transformed into Saccharomyces cerevisiae. The transformed yeast cells were able to catalyze the conversion of oleic acid (C18:1) into linoleic acid (C18:2). The FAD2 gene contains an intron of 2,967 bp in its 5¢ -flanking region, 11 bp upstream from the initiation codon. The intron could be essential for transcriptional regulation of FAD2 gene expression. Several putative promoter elements occur in the 5¢ -flanking region of this gene. A potential TATA basal promoter element occurs at 41 bp upstream from the cap site. Two presumptive helix-loop-helix (bHLH) ...
Date: May 2001
Creator: Kongcharoensuntorn, Wisatre
Partner: UNT Libraries

Changes in Cell Wall Carbohydrate Extractability are Correlated with Reduced Recalcitrance of HCT Downregulated Alfalfa Biomass

Description: Article on changes in cell wall carbohydrate extractability and how these are correlated with reduced recalcitrance of hydroxycinnamoyl transferase (HCT) downregulated alfalfa biomass.
Date: August 2012
Creator: Pattathil, Sivakumar; Saffold, Trina; Gallego-Giraldo, Lina; O'Neill, Malcolm; York, William S.; Dixon, R. A. et al.
Partner: UNT College of Arts and Sciences

Unique applications of cultured neuronal networks in pharmacology, toxicology, and basic neuroscience

Description: This dissertation research explored the capabilities of neuronal networks grown on substrate integrated microelectrode arrays in vitro with emphasis on utilizing such preparations in three specific application domains: pharmacology and drug development, biosensors and neurotoxicology, and the study of burst and synaptic mechanisms. Chapter 1 details the testing of seven novel AChE inhibitors, demonstrating that neuronal networks rapidly detect small molecular differences in closely related compounds, and reveal information about their probable physiological effects that are not attainable through biochemical characterization alone. Chapter 2 shows how neuronal networks may be used to classify and characterize an unknown compound. The compound, trimethylol propane phosphate (TMPP) elicited changes in network activity that resembled those induced by bicuculline, a known epileptogenic. Further work determined that TMPP produces its effects on network activity through a competitive inhibition of the GABAA receptor. This demonstrates that neuronal networks can provide rapid, reliable warning of the presence of toxic substances, and from the manner in which the spontaneous activity changes provide information on the class of compound present and its potential physiological effects. Additional simple pharmacological tests can provide valuable information on primary mechanisms involved in the altered neuronal network responses. Chapter 3 explores the effects produced by a radical simplification of synaptic driving forces. With all synaptic interactions pharmacologically limited to those mediated through the NMDA synapse, spinal cord networks exhibited an extremely regular burst oscillation characterized by a period of 2.9 ± 0.3 s, with mean coefficients of variation of 3.7, 4.7, and 4.9 % for burst rate, burst duration, and inter-burst interval, respectively (16 separate cultures). The reliability of expression of this oscillation suggests that it may represent a fundamental mechanism of importance during periods of NMDA receptor dominated activity, such as embryonic and early postnatal development. NMDA synapse mediated activity produces a precise ...
Date: May 2001
Creator: Keefer, Edward W.
Partner: UNT Libraries

Village Characteristics and Health of Rural Chinese Older Adults: Examining the CHARLS Pilot Study of a Rich and Poor Province

Description: Article on the village characteristics and health of rural Chinese older adults and an examination of the CHARLS pilot study of a rich and poor province.
Date: December 2013
Creator: Yeatts, Dale E., 1952-; Pei, Xiaomei; Cready, Cynthia M.; Shen, Yuying; Luo, Hao & Tan, Junxin
Partner: UNT College of Public Affairs and Community Service

Language Policy, Protest and Rebellion

Description: The hypothesis that language discrimination contributes to protest and/or rebellion is tested. Constitutional language policy regarding administrative/judicial, educational and other matters is measured on three separate scales developed for this study; the status of each minority group's language under its country's policy is measured by another set of scales. Protest and rebellion variables are taken from Gurr's Minorities at Risk study. Findings include an indication that group language status contributes positively to protest and rebellion until a language attains moderate recognition by the government, at which point status develops a negative relationship with protest and rebellion, and an indication that countries with wider internal variations in their treatment of language groups experience higher levels of protest and rebellion on the part of minority groups.
Date: May 2001
Creator: Lunsford, Sharon
Partner: UNT Libraries

Navy Littoral Combat Ship (LCS) Program: Background and Issues for Congress

Description: This report provides background information and potential issues for Congress on the Littoral Combat Ship (LCS), a relatively inexpensive Navy surface combatant equipped with modular "plug-and-fight" mission packages for countering mines, small boats, and diesel-electric submarines, particularly in littoral (i.e., near-shore) waters.
Date: February 5, 2014
Creator: O'Rourke, Ronald
Partner: UNT Libraries Government Documents Department

Qatar: Background and U.S. Relations

Description: This report presents an overview of Qatar's history and recent economic and political developments. The report discusses U.S. relations with Qatar, U.S. military cooperation and foreign assistance, political reform and elections, as well as human rights and social issues.
Date: January 30, 2014
Creator: Blanchard, Christopher M.
Partner: UNT Libraries Government Documents Department