Now showing items 5587-5606 of 14849

• #### Exploring the Use of Environmentally Friendly Fertilizers for Desert Vegetable Production

Field experiments were conducted from 2011 through 2017 to (1) evaluate the responses of vegetable crops to Crystal Green (CG) in comparison to conventional phosphorus (P) fertilizers and (2) to investigate alternative nitrogen management strategies for desert spinach production. The earlier experiments spanned from 2011 to 2016 and employed a novel P source (struvite), a granule-like based P fertilizer marketed as “Crystal Green®”. Responses of Iceberg lettuce (Lactuca sativa), carrot (Daucus carota sativus), onions (Allium cepa) and potato (Solanum tuberosum) to struvite (CG), triple super phosphate (TSP), and monoammonium phosphate (MAP) were compared. Our results revealed that CG compared favorably to TSP but not to MAP when applied as a sole P source. However, certain blends or co-granulated formulations of MAP and CG often provided superior yields than MAP alone. The later studies comprised of four experiments performed from 2016 to 2017. These studies employed various nitrogen (N) sources. The N sources included enhanced efficiency N fertilizers and conventional N products applied at 0,150, and 300 kg N/ha in 2015 and 0, 100, and 200 kg N/ha in 2016. We observed that spinach yields were often maximized at N rates less than 200 kg N/ha considerably below standard commercial practices. The data also revealed that the N source fused safe nitrate (FUSN), a product developed as a substitute for dry ammonium nitrate, generally produced favorable spinach responses relative to the other dry N sources such as ammonium sulfate (AS) and urea. The controlled release fertilizer (CRF) products were observed to be effective N sources for spinach production and are viable options for enhanced efficiency. Contrarily, the nitrification inhibitors caused ammonium damage and yield depression. Overall, the experiments proved that environmentally friendly N and P fertilizers are effective nutrient sources for vegetable production on desert soils.
• #### Exploring uncertainty in first pregnancy

A qualitative study was conducted to explore the phenomenon of uncertainty in women experiencing a first uncomplicated pregnancy. Ten subjects, three from each of the first two pregnancy trimesters and four from the third pregnancy trimester, comprised the sample. Subjects ranged in age from 19 years to 30 years and lived in a southwestern city. Interviews were conducted in the subjects' homes or in the researcher's office over a four month period. Constant comparative analysis of data permitted the researcher to elicit specific uncertainties by trimester and the meaning of uncertainty to women involved in a normal change process. Implications for nursing highlight the need to provide continuity of care from office to hospital and within the hospital environment itself. Providing support by functioning as a mediator between the physician and the patient, nurses could contribute to the pregnant woman's positive perception of her experience. In addition to traditional third trimester childbirth education, classes for first and second trimester women are recommended.
• #### Exposed Memory: Weathering of Regional Architecture

Weathering introduces a language of durability and change throughout time. Architecture and its materials are constituents of place, as is the way they weather and age. The intent of this research is to analyze regional weathering characteristics specific to the American Southwest as a reflection of a sense of belonging that evolves over time.
• #### Exposure to chlorpyrifos and use of pesticides in Arizona

This study of pesticide use and exposure in the Arizona NHEXAS sample explored demographic variation in pesticide use and the feasibility of predicting the subjects' urinary TCPY (a chlorpyrifos metabolite) using questionnaire data. A variety of demographic differences in pesticide use patterns such as frequency of personal application, use of professional exterminators, and frequency of use outside the home were found. In contrast, there were few demographic differences in TCPY, although mean TCPY was higher than in earlier epidemiological studies. Two mulitvariate (multiple regression) methods of predicting TCPY from questionnaire responses were tested. The first method combined pesticide use questions into a scale; the second method treated them separately. R2s were similar and below .25 using either method. Including only subjects reporting some pesticide use raised the R2 to .35. These results suggest that questionnaire responses cannot predict exposure accurately enough to be useful proxies for biological samples.
• #### Expression of a mammalian cytochrome P-450 in Nicotiana tabacum for bioremediation of PCB contaminated soils

Polychlorinated biphenyls (PCBs) are resistant to metabolism in most animal species. The dog has the unique ability to metabolize and eliminate certain PCB congeners, as a result of the activity of the cytochrome P450 isozyme PBD-2. An expressible cDNA coding for PBD-2 has been introduced into the genome of tobacco plants. The PBD-2 cDNA coding sequence and a screenable marker gene coding for neomycin phosphotransferase II were introduced into tobacco leaf disks using a binary Agrobacterium tumefaciens vector system. Southern and Western blot analysis have confirmed chromosomal integration of the cDNA and expression of the PBD-2 polypeptide. Differential centrifugation and Western blot analyses have shown the PBD-2 protein to be associated with a membrane fraction in transgenic tobacco leaf homogenates. Measurements of marker enzymes from linear sucrose gradient fractions and Western blotting show the PBD-2 protein to be associated with the endoplasmic reticulum. Our goal is to develop transgenic plants in which the PBD-2 protein metabolizes PCBs, thus providing a novel method for bioremediation of PCB-contaminated soils.

• #### Expressions of hsc/hsp70 cDNAs in bacteria and comparison with tissue-isolated proteins.

Rat hsc70 and human hsp70 have been expressed in bacteria using the T7 polymerase system. The recombinant proteins, which were the major proteins in E.coli, had the same molecular weights as the tissue-isolated proteins and were immunoactive with hsc70/hsp70 antibodies. ATP binding assay by equilibrium dialysis showed a K$\sb{\rm d}$ for ATP of 0.44 $\mu$M. At saturation, 0.4 mole of ATP was bound per mole of hsc70. Both recombinant and tissue-isolated hsc70/hsp70 have ATPase activities. The denatured substrate, reduced carboxyl methylated $\alpha$-lactalbumin (RCMLA), stimulated ATPase rates of bovine tissue-isolated hsc70/hsp70, but the ATPase rates of rat skeletal muscle and recombinant hsc70 were not changed upon the adding of RCMLA. The analysis of two-dimensional gels showed hsc70/hsp70 isolated from different sources had different isoform patterns. It is speculated that each isoform may have its own substrate specificity.
• #### An extended cavity, self focussing laser optical head

A feasibility study of an "Extended Cavity, Self Focussing Laser Optical Head" for optical data storage applications is presented. A general description of the proposed device is discussed followed by a prediction of its dynamic operation. This is verified by a one dimensional computer model, simulating dynamic laser head behavior. Transient laser phenomena such as longitudinal mode competition and laser frequency modulation are investigated as applicable to the device operation. The self-focussing concept is confirmed by the passive cavity experiment and a geometrical computer model of the cold cavity (i.e. no gain medium).
• #### Extending DEVS-Scheme for control of an oxygen production test bed

This thesis describes an implementation of real-time simulation and control in the DEVS-Scheme environment. The plant is described by discrete event models developed within the event-based control paradigm. A model of the controller is employed to validate its design against a model of the plant. The same model is then migrated over to actual operation by interfacing it to a programmable sensor/actuator interface unit. A system entity structure is employed to generate both the simulation and execution versions of the controller. This methodology is supported by extensions to the DEVS-Scheme simulation environment which facilitate its use for real-time control. As an example, an intelligent controller is developed to control temperature and pressure of an oxygen production prototype system which converts carbon dioxide to oxygen. Such a system is eventually intended to operate autonomously on Mars.

• #### Extension strategies important and feasible for the improvement of poultry production in Bangladesh

The study identified the "most important" and the "most feasible" poultry extension strategies for the improvement of poultry production in Bangladesh during the next five years. Eighty-two poultry Extension agents of the Bangladesh Department of Livestock assessed the importance of the poultry Extension strategies and 15 Extension administrators assessed the feasibility of the "most important" strategies as identified by the agents. The response rate was 82.4% for the extension agents and 100% for the administrators. Descriptive statistics were used to analyse their responses. The respondents identified 38 "most important" poultry Extension strategies and 12 of these strategies as being also "most feasible" for the improvement of poultry production in Bangladesh. In addition, using the Spearman rank order correlation (rs, the study found that there was no significant difference between poultry Extension agents who were Veterinary Science graduates and Animal Husbandry graduates in their ranking of the importance of the poultry extension strategies despite the differences in their educational preparation.