Now showing items 15194-15204 of 15204

    • The z-transform as a general tool in approximation

      Pendleton, Freeman Luke, 1928- (The University of Arizona., 1960)
    • The Zanj Revolt (869-883) in the Abbasid Era

      Muhammad, Suad Mustafa (The University of Arizona., 1981)
    • Zebrafish Video Analysis System for High-Throughput Drug Assay

      Rodríguez, Jeffrey J.; Todd, Douglas Wallace; Rodríguez, Jeffrey J.; Powers, Linda S.; Tharp, Hal S. (The University of Arizona., 2016)
      Zebrafish swimming behavior is used in a new, automated drug assay system as a biomarker to measure drug efficiency to prevent or restore hearing loss. This system records video of zebrafish larvae under infrared lighting using Raspberry Pi cameras and measures fish swimming behavior. This automated system significantly reduces the operator time required to process experiments in parallel. Multiple tanks, each consisting of sixteen experiments are operated in parallel. Once a set of experiments starts, all data transfer and processing operations are automatic. A web interface allows the operator to configure, monitor and control the experiments and review reports. Ethernet connects the various hardware components, allowing loose coupling of the distributed software used to schedule and run the experiments. The operator can configure the data processing to be done on the local computer or offloaded to a high-performance computer cluster to achieve even higher throughput. Computationally efficient image processing algorithms provided automated zebrafish detection and motion analysis. Quantitative assessment of error in the position and orientation of the detected fish uses manual data analysis by human observers as the reference. The system error in orientation and position is comparable to human inter-operator error.

      Cai, Wenlong. (The University of Arizona., 1985)
    • Zhoukoudian: A synthesis of research to date

      Olsen, John W.; Della Croce, Anthony (The University of Arizona., 1995)
      The site of Zhoukoudian has been studied for over 70 years. During this time, a great deal of change has occurred in both analytical methodology and paradigmatic models concerning human prehistory. Zhoukoudian presents an opportunity to study both issues of early hominid behavior and the evolution of palaeoanthropological, geological, dating methodology and palaeoenvironmental research over the last eight decades. Zhoukoudian was the first site to exhibit verifiable evidence for the presence of early hominids in East Asia (more than 45 individuals). The site has been established as containing Middle and Upper Pleistocene components. The majority of these (e.g., Locality 1) fall within a Middle Pleistocene context, while the Upper Cave represents an Upper Pleistocene occupation of the site. Modem studies are suggested in light of the recent reworking of some fundamental concepts at Zhoukoudian. These include evidence for hunting vs. scavenging, fire usage and duration of occupation of the site by early hominids, all of which need reevaluation.
    • Zinc Management and Salt Tolerance of Pecan in Arid Regions

      Walworth, James L.; Smith, Cyrus; Blankinship, Joseph C.; Heerema, Richard J. (The University of Arizona., 2021)
      In the alkaline, calcareous soils common to the southwest zinc reacts with hydroxyl and carbonate groups forming compounds of low solubility, reducing its plant availability, and making soil application of zinc oxide (ZnO) or zinc sulfate (ZnSO4) impractical. Therefore, foliar application of zinc in southwestern pecan orchards is common practice. Fertigation with zinc-ethylenediaminetetraacetic acid (Zn-EDTA) is a possible alternative that has shown positive results in alkaline, calcareous soils. However, many growers fertigating their orchards with Zn-EDTA are still using supplemental zinc foliar sprays due to lack of confidence that soil applied Zn-EDTA can supply enough zinc to the trees. We conducted an experiment to determine if the application of foliar zinc sprays to ‘Wichita’ pecan trees already receiving zinc in the form of Zn-EDTA through fertigation would increase photosynthesis rates. We applied zinc sulfate monohydrate (ZnSO4·H2O), ZnSO4·H2O + Urea Ammonium Nitrate (UAN), Zn-EDTA, water alone, and water + UAN to seven ‘Wichita’ pecans growing in alkaline, calcareous soil in San Simon, AZ. Applications were made twice in 2018 and twice in 2019, Zn-EDTA was applied only in 2019. Photosynthesis measurements were taken approximately two to four weeks following each application. Mid-day stem water potential was also measured to verify that water stress was not limiting photosynthesis. Our results showed that photosynthesis rates were not increased by the application of supplemental foliar zinc sprays in trees fertigated with Zn-EDTA with mean leaf zinc concentrations of untreated leaves in the range of 16-21 mg·kg-1. We concluded that photosynthesis was not zinc limited and that no additional benefit was conferred with regard to photosynthesis from the application of supplemental foliar zinc sprays.Another problem for pecan growers in the southwest is high salt content in the soil. Very little experimentation has been conducted to determine pecan response to saline-sodic conditions. To contribute to this research, we performed an experiment with seven rootstock pecan seedlings grown in alkaline, calcareous, saline-sodic soil at the Safford Agricultural Center in Safford, AZ. The seedlings were chosen from different geographic regions. While we only have knowledge of the maternal genetics of the seedlings which were grown from open-pollinated seed, we hypothesized that seedlings with origins in regions with lower precipitation would be more tolerant of the experimental conditions than those from regions with higher precipitation. It was determined that leaf sodium concentration was more strongly correlated with salt injury in the plants than chlorine. Leaf potassium:sodium (K:Na) ratio was strongly correlated with resistance to salt injury, tree growth rates, and vigor. In support of our hypothesis we found the maternal parentage of the most tolerant seedlings in our experiment was ‘Elliott’, a cultivar with likely Mexican origins (although the ‘Elliott’ cultivar was a seedling selection from Florida). ‘Elliott’ generally outperformed the other seedlings in visual observations of resistance to salt injury and overall plant vigor and stood out with the greatest growth each year and cumulatively throughout the study. ‘Elliott’ had the highest K:Na ratio in 2019, shared the highest K:Na ratio in 2020 with ‘VC1-68’, was among the seedlings with the lowest leaf sodium concentrations during both years, and had the second lowest mortality of all the seedlings chosen. Another issue that pecan growers face is tree to tree variability that is reflected in nutrient acquisition within an orchard. It is important to have knowledge of variability so that each tree receives adequate nutrition. The orchard block mean leaf nutrient concentration should be high enough that all individual trees receive adequate nutrition. Practical leaf sampling of orchards requires sampling only a small portion of the trees randomly, and provides a mean value from which it is difficult to determine minimum (or maximum) nutrient concentrations extent in the sampled orchard block. To address this issue, a two-year experiment was conducted in an orchard in San Simon, AZ. The experimental plot consisted of ‘Wichita’ pecan pollinated with ‘Western’ (every fourth row). Soil and leaf samples were collected each year. Trunk measurements were made in the dormant seasons. Photosynthesis measurements of the ‘Wichita’ trees were made in 2019. The data were analyzed to determine magnitude and patterns of variability. Nutrient uptake varied between the cultivars. A lower mean and more variability in leaf zinc concentrations was found among the ‘Wichita’ trees than ‘Western’ during both years. We concluded that due to lack of variability sources within the orchard block, as well as finding little difference in row to row average mean leaf zinc concentrations, or in average mean leaf zinc concentrations of tree position within rows in either year, that position in the field was not the primary source of variability in leaf zinc concentration. From our 2019 data set we determined that a mean leaf zinc concentration of approximately 25 mg·kg-1 was needed to ensure that no more than 5% of the trees would fall below a target mean leaf zinc concentration (determined from previous research) of 15 mg·kg-1. This concentration is significantly lower than many published recommendations. Further, using the leaf nutrient with the highest coefficient of variance (zinc) for 2019 we determined a range of sample sizes and their associated relative margins of error from the true population mean. A sample size of 35 trees with a relative margin of error of 10% from the true population mean at 95% confidence is recommended for practical sampling purposes.
    • Zola's theory and practice in the genealogical novel

      Wright, Grace, 1901- (The University of Arizona., 1939)

      Van Duyn, Marty J. (The University of Arizona., 1972)

      Stiles, Susan Judith. (The University of Arizona., 1983)
    • Zurbarán and the spirit of the Catholic Reformation in Spain

      Ozmun, James David, 1941- (The University of Arizona., 1970)