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  Partner: UNT Libraries
 Decade: 2000-2009
 Year: 2001
 Collection: UNT Theses and Dissertations
Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases

Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases

Access: Use of this item is restricted to the UNT Community.
Date: May 2001
Creator: Tuck, Terry W.
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 ...
Contributing Partner: UNT Libraries
Teen ages: Youth market romance in Hollywood teen films of the 1980s and 1990s

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

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Date: May 2001
Creator: Murphy, Caryn E.
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.
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A Collapsing Result Using the Axiom of Determinancy and the Theory of Possible Cofinalities

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

Date: May 2001
Creator: May, Russell J.
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
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Isolation and analysis of cotton genomic clones encompassing a fatty acid desaturase (FAD2) gene

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

Date: May 2001
Creator: Kongcharoensuntorn, Wisatre
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 ...
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Unique applications of cultured neuronal networks in pharmacology, toxicology, and basic neuroscience

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

Date: May 2001
Creator: Keefer, Edward W.
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 ...
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Language Policy, Protest and Rebellion

Language Policy, Protest and Rebellion

Date: May 2001
Creator: Lunsford, Sharon
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.
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Distribution and Probable Sources of Nitrate in the Seymour Aquifer, North Central Texas, USA

Distribution and Probable Sources of Nitrate in the Seymour Aquifer, North Central Texas, USA

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Date: May 2001
Creator: Hillin, Clifford K.
Description: This study utilized GIS and statistical methods to map the spatial variability of nitrate and related groundwater constituents in 30 counties above the Seymour Aquifer, analyze temporal patterns of nitrate pollution, identify probable sources of pollution, and recommend water development strategies to minimize exposure to nitrate and reduce future aquifer contamination. Nitrate concentrations in excess of 44 mg/L (US EPA limit) were commonly observed in the Seymour Aquifer region, especially in the central agricultural belt. Data indicated that this is an ongoing problem in the Seymour Aquifer and that agricultural activity and rural septic systems are the likely sources of the nitrate. Inconclusive results emphasized the need for a more comprehensive spatial and temporal water quality monitoring.
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Virtual teams: The relationship between organizational support systems and effectiveness

Virtual teams: The relationship between organizational support systems and effectiveness

Date: May 2001
Creator: Townsley, Carole
Description: This study investigates the effects of eight organizational support systems on virtual team effectiveness in five areas: communication, planning tasks and setting goals, solving problems and making decisions, resolving conflict, and responding to customer requirements. One hundred and eighty surveys were sent to information technology managers and collaborative team members, representing 43 companies. The results indicated that developing new roles for IT professionals and senior managers significantly increased virtual team effectiveness in several areas. The findings support the theory that organizations that utilize virtual teams must create high-level structures, policies, and systems to support the teams and the information tools they use.
Contributing Partner: UNT Libraries
Predictors of Use and Outcomes of Youth and Family Centers

Predictors of Use and Outcomes of Youth and Family Centers

Date: May 2001
Creator: Scharff, Karen
Description: This study analyzed data from Dallas Public Schools and Dallas Youth and Family Centers (YFCs) to explore variables associated with referrals to and utilization of Youth and Family Centers. Data from students enrolled in third, eighth or tenth grade during the 1996-1997, 1997-1998 and 1998-1999 school years were analyzed to determine the reasons for YFC referral and utilization, and to compare standardized test scores and attendance. Of the 6956 students in third, eighth and tenth grades initially referred to YFCs during those three school years, 5173 (74.3%) made at least one YFC visit. The 5173 students made an average of 2.69 visits and accessed an average of 1.18 services per year. Medical visits accounted for 42.5% of YFC visits, and mental health visits accounted for 46% of YFC visits. Results of logistic regression analyses indicate a significant difference for utilization upon referral and continued use of the YFC when the constant is compared to a set of predictor variables. For both analyses, the predictor variables were Chapter I status, LEP status, reason for referral, gender, special education status, ethnicity, distance from home school to referral YFC, food stamp eligibility and referral source. While outcome data regarding attendance and scores on ...
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Age-Dependent Effects Of Chronic GABAA  Receptor Blockade In Barrel Cortex

Age-Dependent Effects Of Chronic GABAA Receptor Blockade In Barrel Cortex

Date: May 2001
Creator: Gargan, Lynn
Description: GABAA receptor binding is transiently increased in rat whisker barrels during the second postnatal week, at a time when neurons in the developing rat cortex are vulnerable to excitotoxic effects. To test whether these GABAA receptors might serve to protect neurons from excessive excitatory input, polymer implants containing the GABAA receptor antagonist bicuculline were placed over barrel cortex for a 4-day period in young (postnatal days 8 - 12) and adult rats. In the cortex of young, but not adult rats, the chronic blockade of GABAA receptors resulted in substantial tissue loss and neuron loss. The greater loss of neurons in young rats supports the hypothesis that a high density of GABAA receptors protects neurons from excessive excitatory input during a sensitive period in development.
Contributing Partner: UNT Libraries
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