Now showing items 14935-14954 of 15343

    • Vacuum chamber experiments in thin film deposition

      Merrill, Spencer Kenneth, 1939- (The University of Arizona., 1967)
    • Vacuum ultraviolet excitation of photoluminescence in fused silica

      Lange, Steven Ralph, 1948- (The University of Arizona., 1973)
    • Vacuum ultraviolet excitation of photoluminescence in silicate glasses

      Jones, Terry Dean, 1945- (The University of Arizona., 1973)
    • Vadose zone characterization pertaining to artificial groundwater recharge, Southern Avra Valley, Arizona

      Yeh, T.C. Jim; Zimmerlund, Benjamin Wayne; Yeh, T.C. Jim (The University of Arizona., 2008)
      The City of Tucson plans to construct a groundwater recharge and recovery facility in southern Avra Valley to infiltrate Central Arizona Project (CAP) water. The Southern Avra Valley Recharge and Recovery Project (SA VSARP) will initially recharge up to 60,000 acre-feet of CAP water per year. Characterization of the vadose zone is important in understanding the behavior of recharged water. Using grain-size distribution data from well cuttings, three lithologic units are defined and a 2-D vertical cross-section is developed in the area of predominant recharge. Soil samples representing each defined lithologic unit are laboratory tested for saturated and unsaturated flow parameters. Soil moisture retention data is fit to the van Genuchten equation to obtain unsaturated flow model parameters. A 1-D unsaturated flow model is developed using VSAFT2 to simulate infiltration of CAP water through the vadose zone.
    • Valdez phase occupation near Taos, New Mexico

      Green, Ernestene L. (The University of Arizona., 1963)
    • Validating developmental sequences in the domain of astronomy using latent trait techniques

      Bergan, John R.; Schwarz, Richard, 1955- (The University of Arizona., 1989)
      The present study was a systematic investigation of developmental skill sequences in the early science domain. Three developmental sequences in the area of astronomy were investigated; knowledge about earth, light and motion. Test items were developed reflecting developmental sequences based on the cognitive processes that are necessary for understanding each task. Data were collected from 1595 kindergarten children from six geographically diverse areas. Latent trait models were constructed to reflect the hypothesized developmental sequences by allowing discrimination and difficulty parameters to vary or by constraining them to equal. Preferred models were obtained by statistical comparison with other models. The knowledge about light and motion were in the hypothesized developmental sequence. Astronomical events that contradicted personal experience, required causal explanations and consisted of extended causal chains were the most difficult for kindergarten children to understand. Investigations concerning the mechanism for conceptual change are necessary.
    • Validating inferences from a standards-based fifth grade mathematics assessment

      D'Agostino, Jerome V.; Stoker, Ginger Lynn (The University of Arizona., 2001)
      The purpose of this study was to investigate the construct validity of the performance levels and their associated descriptors for a state standards-based fifth grade mathematics assessment. Using item responses from 65,291 students, who took the test during the Spring 2000 semester, the study seeks to evaluate the degree to which the descriptions of the performance levels constructed for a state standards-based assessment accurately represent what students at each level know. This was done through four separate, but related, analyses: (1) mapping items to performance level descriptions, (2) assessing the fit of the items to an IRT model, (3) assessing correspondence between items and performance level descriptors, and (4) assessing fit of student responses to the expected response pattern. Results of the analyses show that the performance level descriptions do not provide completely valid portrayals of what students know and are able to do.
    • Validation and adjustment of precipitation simulated by CCM2/BATS over the continental United States

      Dickinson, Robert E.; Chen, Mingxuan; Dickinson, Robert E.; Schotland, Richard; Sellers, William (The University of Arizona., 1994)
      This study compares frequency, intensity and amount of precipitation simulated by NCAR CCM2/BATS with those observed over the continental United States. The emphasis is placed on both spatial and temporal variations. The analysis indicates that: a) The model simulates the seasonal variation of daily intensity reasonably well, while the seasonal variation of frequency is poorly produced. b) The model underestimates the amplitude of intensity, overestimates the amplitude of frequency, and distorts the distribution of phase in diurnal variations. c) The simulated maximum hourly precipitation has almost the same range as is observed. However, the model fails to simulate the overall pattern of maximum hourly precipitation, maximum wet and dry periods from observations. d) The model overestimates the frequency of hourly precipitation by a factor of 13-48 and underestimates intensity by about 90%. These results demonstrate a necessity to adjust simulated precipitation for realistic surface simulation. After adjustment, the simulated intensity is in much closer agreement to the observed value.
    • Validation of a vehicle mobility computer model for heavy earthmoving equipment

      Nowatzki, Edward A.; Matthews, Patricia Aileen, 1963- (The University of Arizona., 1989)
      The computer program WHEEL is a mathematical model which predicts off-road vehicle performance characteristics. The program was developed using empirical relationships resulting from mobility tests on conventional-sized trucks and tires. The model was subsequently validated by comparing the model's predicted values of vehicle performance parameters, such as net drawbar pull, slip, sinkage and torque, with field test results for conventional-sized vehicles. However, validity of the model for predicting the off-road mobility of vehicles with large diameter tires was not established. The purpose of this study was to provide this validation. Values of net drawbar pull and slip for a Case 2390 tractor with 70.2" diameter driven wheels predicted by computer program WHEEL compare favorably with traction data obtained from tractor performance tests conducted by the University of Arizona Department of Agricultural Engineering. Therefore, the model may be used confidently to analyze performance of vehicles with large diameter wheels.
    • Validation of an assessment tool designed to prevent pressure sores

      Wilcox, Robert Lewis, 1940- (The University of Arizona., 1976)
    • Validation of an instrument measuring maintenance of hope in heart transplant patients

      Mishel, Merle H.; Fasbinder, Laurie Guyton, 1957- (The University of Arizona., 1991)
      The purpose of this study was to revise and expand the Hope Maintenance Scale. An exploratory design was used to content analyze qualitative data collected from 226 heart transplant patients in the primary study, "Predictors of Quality of Life in Heart Transplantation". Results supported five of the six original dimensions of hope contained in the Hope Maintenance Scale. The five dimensions substantiated were: Downward Comparison, Fostering Optimism, Belief in a Powerful Other, Avoiding Painful Situations or Material, and Viewing the Situation as Temporary. Subcategories for the dimension of Optimism were generated and termed: Forced Optimism, Guarded Optimism, Euphoria, and Gratefulness. The subcategory of Exceptional Experience was developed for the category of Downward Comparison. Normalizing was proposed as an antecedent of hope. Of subjects who expressed normalizing activities, 60% also used other hope maintenance strategies. Of subjects who reported Threats to Normalizing, 42% used no other hope maintenance strategies.
    • Validation of decreased cardiac output as a nursing diagnosis

      Morton, Nancy Ann, 1952- (The University of Arizona., 1992)
    • Validation of instrument measuring unpredictability management in heart transplant patients

      Murdaugh, Carolyn L.; Marsalla, Jean Engelmann, 1958- (The University of Arizona., 1991)
      The purpose of this study was to revise and expand the Managing Unpredictability Scale (MUS). The sample consisted of 225 heart transplant patients, 73.7% of the total in the primary study. An exploratory design was used to content analyze the qualitative data obtained from one open ended statement on the last page of the booklet from the primary study, "Predictors of Quality of Life in Heart Transplantation". Results substantiated the five original dimensions from the Managing Unpredictability Scale. The five dimensions are: Information Seeking, Setting Limits, Reliance on Selected Physicians, Containing Investment, and Markers. A sixth dimension, Creating Challenges, was generated.
    • Validation of snowpack inventory prediction relationships in Arizona ponderosa pine forests.

      Welch, Barry Wayne,1943-; Ffolliott, Peter F. (The University of Arizona., 1975)
      A validation study of snowpack inventory-prediction equations was conducted during 1972-73. The study was implemented on three different study sites within the ponderosa pine forests in Arizona. Development of inventory-prediction equations to predict the snowpack water equivalent at times not previously described was also completed. Original snowpack inventory-prediction equations did not adequately predict the snowpack water equivalent for the 1972-73 winter season. Thus, new snowpack inventory-prediction equations were developed. The snowpack water equivalent for 1972-73 was five-to-nine times above normal, which may have been a cause for the failure of the original inventory-prediction equations to validate.
    • Validation of urinary incontinence as a nursing diagnosis in Hispanic and non-Hispanic women

      Woodtli, Anne; Hsueh, Kuei-Hsiang; Longman, Alice J.; Bowdish, Joyce (The University of Arizona., 1994)
      This descriptive study used the clinical-retrospective model proposed by Gordon and Sweeney (1979) to clinical identify and validate the defining characteristics for three nursing diagnoses: stress, urge and mixed urinary incontinence in Hispanic (n = 28) and non-Hispanic women (n = 135). Significant differences found between Hispanic and non-Hispanic women were associated with the number of live births and two minor defining characteristics, 'loss when coughing, sneezing, laughing' and 'loss when running' for urge and mixed incontinence, respectively. Characteristics of urge incontinence were different between Hispanic and non-Hispanic women. Major defining characteristics reflected these identified in one previous study by Woodtli and Sidani (1993). The increased level of specificity of the major and minor defining characteristics contrasts with defining characteristics related to urge and stress incontinence currently defined by NANDA. Mixed incontinence was validated as a potential nursing diagnosis in both ethnic groups.
    • Validity of the Jain and Balk analytic model for two-dimensional effects in short channel MOSFETS

      Schrimpf, Ron D.; Hohl, Jakob H.; Shelley, Valerie Anderson, 1957- (The University of Arizona., 1988)
      The Jain and Balk analytic model for two-dimensional effects in short channel MOSFETS is investigated. The effects considered are Drain Induced Barrier Lowering, DIBL, and the maximum electric field, Emax, which influences Drain Induced High Field, DIHF. A scaled short channel design is used as the basis for the investigation. Cases are numerically simulated using the MINIMOS program. DIBL and Emax are calculated using the Jain and Balk model. Model values are compared to numerical simulation values. Results show the model consistently overestimates DIBL. Also, the range for which the model closely estimates Emax is found. Variation in Emax with change of junction depth Xj is investigated. The electric field, Ex, as it varies with depth in the channel is investigated, and compared to the Jain and Balk approximation. The deviations suggest that the model must break down for short channels.
    • Valley National Bank - Executive Branch

      Little, Sidney W.; McCoy, Mack L.; Little, Sidney W. (The University of Arizona., 1963)