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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.
721

Rattus tanezumi in the upland rice terraces of Banaue, Philippines: demography, habitat use, crop damage and yield assessment.

Miller, Rachel Weslie, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2007 (has links)
Rodents cause significant damage to agricultural crops throughout the world, including rice, the staple food for the increasing population of Southeast Asia. Little is known about the ecology of pest rodent species, resulting in much effort being concentrated on ineffective, time consuming control practices. This research was designed to understand the demography and habitat use of the major pest rodent (Rattus tanezumi) of the Banaue rice terraces in order to identify the most efficient time and location to undertake pest control. Rodent crop damage and associated yield loss was also assessed in order to provide information for a cost : benefit analysis of rodent control practices. And the beliefs, perceptions and practices of Banaue rice farmers were investigated to assist in identifying future compatible rodent control programs. Replicated cage trapping was undertaken for a twelve month period over the entire rice cropping season in two study sites in the Municipality of Banaue Philippines. The breeding season of R. tanezumi corresponded with periods of food availability from the transplanted to ripening stages of the rice crop. A non-breeding season occurred from the fallow to seedling stages. The distinct breeding season occurred within the rice fields and adjacent village and scrub habitats. Radio-tracked and spool-and-line tracked R. tanezumi moved from adjacent habitats into the rice field during the breeding season, and individuals persisted in all habitat types, including the rice field, during the fallow, nonbreeding season. Overall rice yield was significantly greater (43%) in areas where rodents were excluded by fencing compared to areas where rodents were not excluded. More rodent damage to rice tillers occurred at the booting than at the ripening stage of the rice crop. These results suggest that to prevent rodent damage, control should be undertaken at the end of the R. tanezumi non-breeding season (prior to transplanting), before rodent numbers multiply and crop damage occurs. Further, the cost-benefit analysis of non-chemical rodent control programs in Banaue, suggests that benefits accrue once yield loss is likely to exceed 5%.
722

Micromechanics of rate-independent multi-phase composites : application to Steel Fiber-Reinforced Concrete

Ouaar, Amine 10 July 2006 (has links)
Composite materials reinforced with particles or fibers are widely used in industrial applications due to their good mechanical, thermal, and electrical properties. Consequently, for the scientific community as well as the industry, an important challenge is to understand the relationship between the microstruture and the macroscopic response in order to design composite materials with optimised properties. In this thesis, we study a class of inclusion-reinforced multi-phase composites. Our main objective is to develop a micromechanical model and the corresponding numerical algorithms which enable the simulation of the rate-independent mechanical response. The proposed model is based on an incremental Hill-type formulation and uses the two-step Mori-Tanaka/Voigt mean-field homogenisation schemes. The crucial issues of the choice of reference comparison materials and Eshelby's tensor computation are examined In parallel, an experimental study consisting in four-point bending tests performed on plain concrete and steel fiber-reinforced concrete (SFRC) specimens, is carried out with the aim of achieving an appropriate modelling of SFRC, and collecting data for the validation of our model predictions. The accuracy and the efficiency of the proposed approach are evaluated through numerical simulations. Several discriminating tests of concrete, metal, and polymer matrix composites are carried out. A two-scale approach is developed in order to simulate, within reasonable CPU time and memory usage, the response of realistic structures under complex loadings. In many cases our estimates are validated against finite element computations and experimental results.
723

Sales assistants serving customers with traumatic brain injury

Goldblum, Glenn. January 2005 (has links)
Thesis (D. Phil.(Communication Pathology))--University of Pretoria, 2005. / Summary in English and Afrikaans. Includes bibliographical references.
724

The brain, attention, and eye movements /

Drew, Anthony Scott, January 2006 (has links)
Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 72-80). Also available for download via the World Wide Web; free to University of Oregon users.
725

Assessment of hyperspectral features and damage modeling in bitumen flotation process

Bhushan, Vivek 06 1900 (has links)
Flotation process is mineral processing technique used for separating valuable minerals from the gangue. The research presented in this thesis deals with assessing features that can help in measuring the performance (observing) bitumen flotation process and modeling damage in flotation units. A timely measure of oilsands and process stream contents can be used to observe and control the separation performance. To this end, flotation experiments were conducted and hyperspectral images of the ore and the process stream were taken to determine whether spectral information can predict the bitumen and fines content of ore samples and establish relationship a between these variables and the froth colour. Several features that appear to correspond to clay and quartz were present. Flotation cells are prone to wear damage by particles entrained in the slurry. A wear damage model was developed to predict the damage accumulated over a period of time. Particle image velocimetry experiments were conducted on physical flotation model to understand the flow behavior of the solid particles near the wall of the flotation unit. A preliminary wear test was conducted for qualitative assessment of wear. Recommendations were made for validating the damage model. / Engineering Management
726

Functions of TRF2: From Telomere Protection to DNA Damage Signaling and Vascular Remodeling

Khan, Sheik Jamaludin 18 June 2008 (has links)
TTAGGG repeat factor 2 (TRF2) is a protein that plays an important role in capping telomere ends from DNA damage responses. Telomere DNA consists of double strand repeats of the TTAGGG sequence ending with a 3'single-stranded overhang of the guanine strand (the G-strand overhang). TRF2 protects telomeres from being recognized as double-stranded breaks. It is thought that this protection is performed through the formation of T-loop structures and recruitment of proteins into a complex called shelterin. The exact mechanism of T-loop formation is unknown. I show with in vitro biochemical studies that TRF2 specifically interacts with telomeric ss/ds DNA junctions and binding is sensitive to the sequence of the G-strand overhang and double-stranded DNA sequence at the junction. Binding assays with TRF2 truncation mutants suggest that TRF2 interacts with both the double-stranded DNA through the C-terminal DNA binding domain and the G-strand overhang through the N-terminus. Mobility shifts and atomic force microscopy with truncation mutants bound to telomeric DNA also show that a previously uncharacterized "linker" region within TRF2 is involved in DNA-specific TRF2 oligomerization. From these observations, I suggest that TRF2 forms protective loops by oligomerizing through both a previously characterized dimerization domain and the linker region. I propose that loop formation involving the telomere ends is accomplished through direct interactions between TRF2 and the G-strand overhang. In addition to DNA protection, a new role has emerged for TRF2 in sensing DNA damage. TRF2 can be phosphorylated within its dimerization domain by ATM and recruited to DNA damage foci in cells. The inhibition of TRF2 function alone has been shown to induce senescence and apoptosis in vascular endothelial cells. Since the common stimuli for a senescence phenotype is activation of a DNA damage response, I studied the relationship between DNA damage and TRF2 phosphorylation. Ex-vivo characterization of DNA damage-induced changes in vascular smooth muscle cells (VSMC) was undertaken. VSMC treated with H202 induced an increase in reactive oxygen species (ROS), and 8-oxo-guanine accumulation resulting in cell cycle arrest, chromatin condensation and a senescent phenotype. Interestingly phosphorylated TRF2 and ATM were also up regulated. Balloon injury was used to test the connection between phosphorylated TRF2 and senescence during vascular remodeling in rat arteries. Vascular remodeling as judged by neointima formation was associated with accumulation of 8-oxo-guanine, DNA damage signaling, including phosphorylated TRF2, an increase in cell cycle inhibitors and senescence. These events were exaggerated in aged animals and are consistent with a role in telomere dysfunction, and age related diseases.
727

Whole Body Periodic Acceleration Reduces Levels of Delayed Onset Muscle Soreness After Eccentric Exercise

Serravite, Daniel H. 14 May 2010 (has links)
Context: Several recovery strategies have been used, with limited effectiveness, to reduce the muscle discomfort or pain and the diminished muscle performance following a bout of unaccustomed physical activity, a condition known as delayed onset of muscle soreness (DOMS). Muscle damage in this condition is associated with mechanical disruption of the muscle and connective tissue and inflammation and increased oxidative stress. Low frequency, low intensity, whole body periodic acceleration (WBPA) that increases nitric oxide (NO) release from vascular endothelium into the circulation through increased pulsatile shear stress offers a potential solution. This is because endothelial derived nitric oxide has anti-inflammatory, antioxidant and anti-nociceptive properties. Objective: The purpose of this study was to examine the effects of WBPA on the pain and diminished muscle performance associated with DOMS induced by unaccustomed eccentric arm exercise in young male subjects. Design: Longitudinal. Setting: University Exercise Physiology Laboratory. Participants: Seventeen active men, 23.4 +/- 4.6 yr of age. Intervention: Subjects made six visits to the research facility over a two-week period. On day one, the subject performed a 1RM elbow flexion test and was then randomly assigned to the WBPA or control group. Criterion measurements were taken on Day 2, prior to and immediately following performance of the eccentric exercise protocol (10 sets of 10 repetitions using 120% of 1RM) and after the recovery period. During all subsequent sessions (24, 48, 72, and 96 h) these data were collected before the WBPA or passive recovery was provided. Main Outcome Measures: Isometric strength (MVC), blood markers (CPK, MYO, IL-6, TNF-alpha and Uric Acid), soreness, pain, circumference, and range of motion (ROM). Results: Significantly higher MVC values were seen for the WBPA group across the entire 96 h recovery period. Additionally, within group differences were seen in CPK, MYO, IL-6, soreness, pain, circumference, and ROM showing a smaller impact and more rapid recovery by the WBPA group. Conclusion: Application of WBPA hastens recovery from DOMS after eccentric exercise. Given the lack of other potential mechanisms, these effects appear to be mediated by the increased NO release with WBPA.
728

Moderators of verbal cueing effects on novel naturalistic action performance among stroke patients /

Green, Sheryl M. January 2002 (has links)
Thesis (M.A.)--York University, 2002. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 68-73). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ75382
729

Cave and cliff swallows as indicators of exposure and effects of environmental contaminants on birds from the Rio Grande, Texas

Musquiz, Daniel 15 November 2004 (has links)
Cave (Petrochelidon fulva) and cliff swallows (Petrochelidon pyrrhonota) were collected along the Rio Grande and evaluated as potential indicators of environmental contamination. The Rio Grande receives toxic substances from agricultural, industrial, municipal, and non-point sources; consequently, high levels of contaminants have been detected in birds, mammals, fishes and sediments. Swallows were obtained from 8 sites between Brownsville and El Paso, as well as from a reference site in Burleson County, 320 miles north of the nearest site of the Rio Grande. Blood samples were analyzed by flow cytometry, a technique that allows the detection of DNA damage in blood and other tissues. Plasma samples were analyzed for thyroid hormones using a radioimmunoassay technique. Organochlorines and trace metal analysis was limited to a few samples. DDE and PCB levels were below levels known to cause reduced hatching, embryo mortality, and deformities, Hg, Pb, and As were below detection, and Se, Ni and Cr concentrations were lower than levels known to cause harm in birds. Neither species showed sex-related differences in chromosome damage. Cave swallows from the Del Rio area had the highest levels of DNA variation, which may be indicative of DNA damage, possibly from PAHs exposure. Previous studies indicate that sediment samples from tributaries near Del Rio have high levels of chromium compared to other sites along the Rio Grande. A significant increase in DNA variation between sampling years was detected in cave swallows from Llano Grande Lake. Wildlife samples collected from Llano Grande Lake have recorded high levels of DDE and PCBs; in addition, this urban/agricultural contaminant sink appears to be affected by PAH exposure. T3 levels were below the detection limit of the radioimmunoassay. There were no gender related differences in T4 levels in cave swallows. Cave swallows sampled from Laredo had significantly higher T4 levels than those from birds at other sites during 1999. It was not possible to determine thyroid hormone disruption in plasma samples. Thyroid hormone and flow cytometry data were useful in establishing baseline data. Areas of concern based on genotoxic data include Llano Grande Lake, Del Rio, and El Paso.
730

Measurements of moisture suction in hot mix asphalt mixes

Kassem, Emad Abdel-Rahman 30 October 2006 (has links)
The presence of moisture in hot mix asphalt (HMA) causes loss of strength and durability of the mix, which is referred to as moisture damage. This study deals with the development of experimental methods for measuring total suction in HMA, which can be defined as the free energy state of water in HMA mixes. The total suction is related to the ability of moisture to get into the mix under unsaturated conditions; it is also related to the ability of the mix to retain moisture. Soil suction has been studied extensively. However, suction in HMA as a porous material and its relationship to moisture damage have not been studied. The development of a procedure to measure the total suction in HMA mixes is the first objective of this research. The second objective is to relate suction measurements to physical and chemical properties of the mixtures. The objectives were achieved in two phases. In the first phase, the total suction was measured in HMA specimens with different types of aggregates (limestone and granite), and with different air void distributions and aggregate gradations. The results of this phase showed that the drying test using a 60 oC temperature-controlled room is the proper setup for measuring the total suction in HMA using thermocouple psychrometers. The characteristics of suction-moisture content curves were found to be related to the air void distribution in HMA. In the second phase, total suction was measured in sand asphalt specimens. These specimens had different combinations of aggregates and binders with different bond energies and exhibited different field performance in terms of resistance to moisture damage. The suction measurements in sand asphalt specimens were used to calculate the moisture diffusion coefficient. The results revealed that water diffused into sand asphalt specimens that are known to have poor resistance to moisture damage faster than those that are known to have good resistance to moisture damage

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