Browsing by Subject "availability"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Imazethapyr: red rice control and resistance, and environmental fate(Texas A&M University, 2005-11-01) Avila, Luis Antonio deImazethapyr was recently approved for use in rice, but limited information is available regarding its efficacy, environmental fate or potential red rice resistance. Therefore, experiments were conducted to 1) determine the effect of flooding time, and stage of imazethapyr application in red rice control, 2) assess the acetolactate synthase resistance to imazethapyr on red rice ecotypes, 3) determine the relative photolysis of imazethapyr, and 4) determine the effect of soil and moisture on imazethapyr adsorption and availability. When imazethapyr was applied in sequential application of PRE followed by a POST application, to achieve >95% red rice control, flood needed to be established within 14 DAT when imazethapyr was applied EPOST, and 7 DAT when imazethapyr was applied LPOST. Delaying the flood up to 21 DAT reduced rice grain yield for both EPOST and LPOST application timings. Based on enzymatic activity, the mean I50 values were 1.5, 1.1, 1.5, 1.6, 20.8, and 590.6 mM of imazethapyr, respectively, for LA 5, MS 5, TX 4, ??Cypress??, ??CL-121??, and ??CL-161??. CL-161 was 32 times more resistant than CL-121, and at least 420 times more resistant than the average of the red rice ecotypes and ??Cypress??. Results from the ALS assay showed that red rice ecotypes and Cypress had high susceptibility to imazethapyr when compared with the tolerant CL-121 and the resistant CL-161. Measurable enzymatic tolerance to ALS-inhibiting herbicides has not yet developed in these red rice ecotypes. Imazethapyr quantum yield (fI ) was 0.023 ?? 0.002 while the hydroxyl radical rate constant ( I OH k?? ) was 2.8 ?? 0.44 x 1013 M-1 h-1. These results show that imazethapyr is susceptible to both direct and indirect photolysis. The results also show that imazethapyr photolysis in paddy water will be affected by turbidity due to its impact on the availability of sunlight to drive direct and indirect photolysis reactions. Imazethapyr was more available and more concentrated in sandy soil. With higher amounts of water in soil there was greater amount of imazethapyr in soil solution and a lower concentration of herbicide due to dilution. The double centrifuge method provided a better estimate of plant available herbicide.Item Measuring availability of healthful foods in two rural Texas counties(2009-05-15) Bustillos, Brenda DianeA comprehensive in-store survey may capture the availability of healthful food alternatives in different store types in two rural counties. The purpose of this study was to: (1) compare the availability of healthful foods in two rural Texas counties; and (2) compare the variety of healthful foods in two rural Texas counties. This study also acts as a pilot test for further food availability research in four other rural counties of the Brazos Valley. An unobtrusive, observational survey was used to measure availability of healthful food in all (100%) grocery, convenience, and discount stores (n=44) in two rural counties in the Brazos Valley of Texas. Results from the surveys indicated that availability of healthful food alternatives varied greatly among the three different store types and two counties surveyed. Grocery stores (n=7) were more likely than convenience (n=31) and discount (n=6) stores to offer fresh fruits and vegetables, leanmeat options, and low-fat/skim milk products. Fresh fruits and vegetables were available in 100% of grocery stores. Only 16.1% of convenience stores, compared with 0.0% in discount stores, offered fresh fruits and vegetables. Variety of fruits and vegetables varied greatly among the three different store types and the two counties surveyed. Findings suggest that the survey utilized was feasible in determining the availability of healthful food items in two rural counties. Implications of this study include the need for knowledge and awareness of rural consumers and rural food supply. Furthermore, nutrition education for rural consumers and those purchasing foods provided to rural areas is desired. This study provided that further investigation into the availability of healthful foods in rural areas is needed.Item Scheduling screening inspections for replaceable and non-replaceable systems(2009-05-15) Aral, BahadirThis dissertation focuses on developing inspection schedules to detect non-self- announcing events which can only detected by inspections. Failures of protective sys- tems ,such as electronic equipments, alarms and stand-by systems, incipient failures and the emergence of certain medical diseases are examples of such events. Inspec- tions are performed at pre-determined times to detect whether or not the event has occurred, and necessary actions are taken upon the detection. In this research, my interest is in developing effective inspection schedules to detect non-self-announcing events that balance system downtime and inspection effort. To evaluate the quality of an inspection schedule, I use the availability (for re- placeable) and the detection delay (for non-replaceable systems) as performance mea- sures. When the monetary cost of inspection and the cost of delay are difficult to determine, non-monetary performance measures become more meaningful. In this research, the focus is on maximizing availability or minimizing detection delay given a limited number of inspections or a limited inspection rate. I show that for replace- able and non-replaceable systems, it is possible to construct inspection schedules that perform better than periodic inspection with respect to our performance measures. The occurrence of the event I would like to detect may be influenced by certain individual characteristics. For instance, the risk of developing a certain type of dis- ease might be different for different subgroups within the population. In this case, because of the non-homogeneity in the population, benefits of performing screening tests may not be fully achieved for each sub-group by using an inspection strategy developed for the entire population. Thus, it may be of value for an individual to learn more information about his/her likehood to have the disease. To address this issue, I analyze the change in the expected delay if schedules are based on the whole population information or the individual information and provide numerical results.Item Using Multiple Household Food Inventories to Measure Food Availability in the Home(2010-10-12) Sisk, Cheree L.The purpose of this study was to determine the feasibility of conducting multiple household food inventories over the course of 30 days to examine weekly food variability. Household food availability influences the foods individuals choose to consume; therefore, by assessing the home food environment a better understanding of what people are eating can be obtained. Methods of measuring home food availability have been developed and tested in recent years; however most of these methods assess food availability on one occasion only. This study aimed to capture "usual" availability by using multiple assessments. After the development and pre-testing of the 171-item home observation guide to determine the presence and amount of food items in the home (refrigerator, freezer, pantry, elsewhere), two trained researchers recruited a convenience sample of 9 households (44.4% minority), administered a baseline questionnaire (personal info, shopping habits, food resources, and food security), and conducted 5 in-home assessments (5-7 day interval) over a 30-day period. Each in-home assessment included shopping and fast food activities since the last assessment and an observational survey of types and amounts of foods present. The final in-home assessment included an audio recorded interview on food habits and beliefs. Complete data were collected from all 9 women (32.8 y +/- 6.0; 3 married; 4 +/- 1.6 adults/children in household; 4 SNAP; 6 food insecure) and their households. Weekly grocery purchases (place, amount, and purpose) use (frequency) varied from once (n=1) to every week (n=5); 4 used fast food 2-3 times/wk for 4 weeks. Quantity and types of fresh and processed fruits and vegetables varied by week and by family. The feasibility of conducting multiple in-home assessments was confirmed with 100% retention from all participants. This methodology is important in that it provided detailed information on intra-monthly variation in food availability. The findings suggest the inadequacy of a single measure to assess food availability in the home.