Now showing items 38062-38081 of 39117

    • V2 Receptor and AQP2 Distribution in the Kangaroo Rat Kidney

      Siordia, Juan Arturo (The University of Arizona., 2011-05)
    • Vaccinate AZ Website: An Example of Improving Online Parent Education Materials

      Parker, Sheila; Morice, Natalie Renee (The University of Arizona., 2015)
      Early childhood vaccinations have become a highly debated public health topic in the past two years. Parents, politicians, doctors, and celebrities alike each have their own opinion on vaccines and vaccine schedules for children. One way to improve vaccination rates and decrease personal belief exemptions is to improve information sources to be more user-friendly and simple for parents to learn about vaccines. In 2013, researchers at the Arizona Department of Health Services (ADHS) cited a need for improving its website and other patient education strategies to improve childhood vaccination rates across the state (ADHS). Currently, the immunization section of ADHS website has limited parent resources, many of which are long documents without section headings or images, making it easy for parents to become overwhelmed and confused. Creating more easy-to-use sources with simple language may be one way to improve parent knowledge on the importance of early childhood vaccinations and reduce personal belief exemptions. The following paper details a website created to educate the general public on early childhood vaccinations.
    • 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.
    • Vagueness and Borderline Cases

      Horgan, Terry; Lavine, Shaughan; Daly, Helen; Sartorio, Carolina (The University of Arizona., 2011)
      Vagueness is ubiquitous in natural language. It seems incompatible with classical, bivalent logic, which tells us that every statement is either true or false, and none is vaguely true. Yet we do manage to reason using vague natural language. In fact, the majority of our day-to-day reasoning involves vague terms and concepts. There is a puzzle here: how do we perform this remarkable feat of reasoning? I argue that vagueness is a kind of semantic indecision. In short, that means we cannot say exactly who is bald and who is not because we have never decided the precise meaning of the word 'bald'--there are some borderline cases in the middle, which might be bald or might not. That is a popular general strategy for addressing vagueness. Those who use it, however, do not often say what they mean by 'borderline case'. It is most frequently used in a loose way to refer to in-between items: those people who are neither clearly bald nor clearly not bald. But under that loose description, the notion of borderline cases is ambiguous, and some of its possible meanings create serious problems for semantic theories of vagueness.Here, I clarify the notion of a borderline case, so that borderline cases can be used profitably as a key element in a successful theory of vagueness. After carefully developing my account of borderline cases, I demonstrate its usefulness by proposing a theory of vagueness based upon it. My theory, vagueness as permission, explains how classical logic can be used to model even vague natural language.
    • Valdez phase occupation near Taos, New Mexico

      Green, Ernestene L. (The University of Arizona., 1963)
    • Valid-time indeterminacy.

      Dyreson, Curtis Elliott.; Snodgrass, Richard T.; Downey, Peter J.; Peterson, Larry (The University of Arizona., 1994)
      In valid-time indeterminacy, it is known that an event stored in a temporal database did in fact occur, but it is not known exactly when the event occurred. We extend a tuple-timestamped temporal data model to support valid-time indeterminacy and outline its implementation. This work is novel in that previous research, although quite extensive, has not studied this particular kind of incomplete information. To model the occurrence time of an event, we introduce a new data type called an indeterminate instant. Our thesis is that by representing an indeterminate instant with a set of contiguous chronons and a probability distribution over that set, it is possible to characterize a large number of (possibly weighted) alternatives, to devise intuitive query language constructs, including schema specification, temporal constants, temporal predicates and constructors, and aggregates, and to implement these constructs efficiently. We extend the TQuel and TSQL2 query languages with constructs to retrieve information in the presence of indeterminacy. Although the extended data model and query language provide needed modeling capabilities, these extensions appear to carry a significant execution cost. The cost of support for indeterminacy is empirically measured, and is shown to be modest. We then show how indeterminacy can provide a much richer modeling of granularity and now. Granularity is the unit of measure of a temporal datum (e.g., days, months, weeks). Indeterminacy and granularity are two sides of the same coin insofar as a time at a given granularity is indeterminate at all finer granularities. Now is a distinguished temporal value. We describe a new kind of instant, a now-relative indeterminate instant, which has the same storage requirements as other instants, but can be used to model situations such as that an employee is currently employed but will not work beyond the year 1995. In summary, support for indeterminacy dramatically increases the modeling capabilities of a temporal database without adversely impacting performance.
    • Validating a Neonatal Risk Index to Predict Necrotizing Enterocolitis

      Effken, Judith A.; Gephart, Sheila Maria; Reed, Pamela G.; Jones, Elaine G.; Halpern, Melissa D.; Effken, Judith A. (The University of Arizona., 2012)
      Necrotizing enterocolitis (NEC) is a costly and deadly disease in neonates. Composite risk for NEC is poorly understood and consensus has not been established on the relevance of risk factors. This two-phase study attempted to validate and test a neonatal NEC risk index, GutCheck(NEC). Phase I used an E-Delphi methodology in which experts (n=35) rated the relevance of 64 potential NEC risk factors. Items were retained if they achieved predefined levels of expert consensus or stability. After three rounds, 43 items were retained (CVI=.77). Qualitative analysis revealed two broad themes: individual characteristics of vulnerability and the impact of contextual variation within the NICU on NEC risk. In Phase II, the predictive validity of GutCheck(NEC) was evaluated using a sample from the Pediatrix BabySteps Clinical Data Warehouse (CDW). The sample included infants born<1500 grams, before 36 weeks, and without congenital anomalies or spontaneous intestinal perforation (N=58,818, of which n=35,005 for empiric derivation and n=23,813 for empiric validation). Backward stepwise likelihood-ratio method regression was used to reduce the number of predictive factors in GutCheck(NEC) to 11 and derive empiric weights. Items in the final GutCheck(NEC) were gestational age, history of a transfusion, NICU-specific NEC risk, late onset sepsis, multiple infections, hypotension treated with Inotropic medications, Black or Hispanic race, outborn status, metabolic acidosis, human milk feeding on both day 7 and day 14 (reduces risk) and probiotics (reduces risk).Discrimination was fair in the case-control sample (AUC=.67, 95% CI .61-.73) but better in the validation set (AUC=.76, 95% CI .75-.78) and best for surgical NEC (AUC=.84, 95% CI .82-.84) and infants who died from NEC (AUC=.83, 95% CI .81-.85). A GutCheck(NEC) score of 33 (range 0-58) yielded a sensitivity of .78 and a specificity of .74 in the validation set. Intra-individual reliability was acceptable (ICC (19) =.97, p<.001). Future research is needed to repeat this procedure in infants between 1500 and 2500 grams, complete psychometric testing, and explore unit variation in NEC rates using a comprehensive approach.
    • Validating and Testing A Model to Predict Adoption of Electronic Personal Health Record Systems in the Self-Management of Chronic Illness in the Older Adult

      Effken, Judith A.; Logue, Melanie D.; Reed, Pamela G.; Murdaugh, Carolyn (The University of Arizona., 2011)
      Problem statement: As a result of the aging population, the number of people living with chronic disease has increased to almost 50% (CDC, 2004). Two of the main goals in treating patients with chronic diseases are to provide seamless care from setting to setting and prevent disability in the older adult. Many have proposed the use of electronic personal health record systems (PHRs) in the self-management process, but adoption remains low. The purpose of this research was to validate and test an explanatory model of the barriers and facilitators to older adults' adoption of personal health records for self-managing chronic illnesses. The long range goal of the research is to use the explanatory model to develop interventions that will maximize the facilitators and minimize the barriers to adoption. Methods: A preliminary attempt to capture the essential barriers and facilitators that predict adoption of PHRs among older adults with chronic illness was synthesized from the literature. In Phase One of the study, the model was integrated from existing literature and validated using a Delphi method. In Phase Two of the study, the model was pilot tested and refined for future investigations. Findings: The results of this study validated the Personal Health Records Adoption Model (PHRAM) and a preliminary instrument that measured barriers and facilitators to the adoption of PHRs in older adults who are self managing chronic illness. Additional findings indicate that while seniors are seeking options to manage their health and have expressed an interest in using Internet-based PHRs, they may require assistance to gain access to PHRs. Implications: The potential for PHRs to increase patient autonomy and reduce for disability and the resulting negative health consequences needs further investigation as we move into the next era of healthcare delivery. The results of this study provided the foundation for continued theoretically-based research in this area.

      Bergan, John R.; Lane, Suzanne; Bergan, John R.; Sabers, Darrell; Nicholson, Glen; Mishra, Shitala P. (The University of Arizona., 1986)
      The present study was a systematic investigation of hierarchical skill sequences in the beginning reading domain. The hierarchies included skills from the traditional approach to reading which reflect bottom-up processing and skills from the conceptual area of print awareness which reflect top-down processing. Researchers supporting the bottom-up approach view reading as a process in which the child extracts information from the text to gain knowledge of the print. The bottom-up processes examined were in the areas of letter recognition and letter naming, and identification of letter sounds and phonemes. The top-down processing approach views reading as a task in which the child brings his/her past experiences and knowledge about the world to gain information about print. The top-down processes examined were in the areas of print identification, inferring a word in context, and print directionality rules. Hierarchical skill sequences were developed within each of the specific areas reflecting the top-down and bottom-up processing theories. Items were developed to reflect the skill sequences based on the cognitive processes that are necessary for correct performance. This involved varying the task demands imposing various requirements of cognitive processing. The data were from 13,189 Head Start children ranging from 3 to 6 years of age. Latent trait models were constructed to reflect the viii ix hypothesized skill sequences by allowing the aj (discrimination) and bj (difficulty) parameters to be free to vary or by constraining them to be equal to other parameters. To arrive at a preferred model, each latent trait model that represented a hypothesized skill sequence was statistically compared against alternative latent trait models. The results from the present investigation supported the hierarchical skill sequences reflecting skills within the traditional area of reading. However, some of the skill sequences from the conceptual area of print awareness were not clearly supported. While the results provide a deeper understanding of beginning reading skill sequences reflecting top-down and bottom-up processing theories, future research is needed to delineate the specific skills which promote later reading ability once the child is in formal reading instruction.
    • Validating cognitive skill sequences in the early social development domain using path-referenced technology and latent trait models.

      Bergan, John R.; Feld, Jason Kane.; Morris, Richard J.; Mishra, Shitala P. (The University of Arizona., 1988)
      The present study was a systematic investigation of hierarchical skill sequences in the early social development domain. Recent research has suggested that social development may be conceptualized as a phenomena involving a hierarchical sequencing of competencies. In particular, social development may involve sequential changes in capability, reflecting successively higher levels of functioning within these competencies. The conceptual problem of this study focused on the construction and validation of a meaningful representation of ability in early social development. Ability was conceptualized as a composite of cognitive procedures governing the performance of specific tasks. The process for constructing skill sequences to reflect ability involved identifying task characteristics or demands which imposed various requirements on cognitive functioning. Hierarchical skill sequences were constructed to tap a variety of capabilities within the early social development domain. These skill sequences included understanding emotions, identifying and mediating needs, understanding friendships, and understanding fairness in decision making. Assessment items were developed to reflect each of these skill sequences based on the cognitive processes that are necessary for correct performance. This involved varying the task demands imposing various requirements on cognitive processing. The data were from 18,305 Head Start children ranging from 30 to 83 months of age. Latent trait models were constructed to reflect the hypothesized skill sequences by allowing the discrimination and difficulty parameters to be free to vary or by constraining them to be equal to other parameters. To arrive at a preferred model, each latent trait model was statistically compared against alternative latent trait models. In general, the results from the present investigation supported the hypothesis that the acquisition of social skills is a developmental phenomena involving a hierarchical sequencing of competencies. Moreover, the study supports the assumption that changes in capability can be defined by progress toward abstraction, complexity, stability, and the handling of increasing quantities of information. While the results provide a deeper understanding of early social development, future research is needed to extend the developmental structure to higher levels of ability. Moreover, research is needed to determine how the information gleaned from developmental assessment can be utilized in planning learning experiences to enhance development.
    • 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 hierarchical sequences in the design copying domain using latent trait models.

      Bergan, John R.; Burch, Melissa Price.; Mishra, Shitala P.; Obrzut, John E. (The University of Arizona., 1988)
      The present study was a systematic investigation of hierarchical skill sequences in the design copying domain. The factors associated with possible variations in task difficulty were delineated. Five hierarchies were developed to reflect variations in rule usage, the structuring of responses, presence of angles, spatial orientations, and stimulus complexity. Three-hundred thirty four subjects aged five through ten years were administered a 25 item design copying test. The data were analyzed using probabilistic models. Latent trait models were developed to test the hypothesized skill sequences. Each latent trait model was statistically compared to alternate models to arrive at a preferred model that would adequately represent the data. Results suggested that items with predictable difficulty levels can be developed in this domain based on an analysis of stimulus dimensions and the use of rules for task completion. The inclusion of visual cues to guide design copying assists accurate task completion. Implications of the current findings for facilitating the construction of tests which accurately provide information about children's skill levels were discussed. The presence of hierarchical skill sequences in a variety of ability domains was supported.
    • 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.
    • Validating the development of male and female preschoolers' help-seeking, goal-setting and planning, and self-evaluation using latent trait models.

      Reddy, Linda Ann.; Bergan, John R.; Mishra, Shitala P.; Feld, Jason K. (The University of Arizona., 1994)
      The present study investigated the early development of three self-regulated learning strategies--help seeking, goal setting and planning, and self evaluation for male and female preschoolers. Skill sequences were developed by identifying demand attributes that imposed requirements on cognitive functioning. The demand attributes of adult assistance and task complexity were identified for all three learning strategies. Variations in adult assistance and task complexity were examined to determine the relative difficulty for male and female preschoolers to perform skills within each learning strategy. This study included data from 10,291 preschoolers, age 2 to 6 years, from Head Start and public preschool programs across the country. The sample included approximately 5,000 males and 5,000 females from culturally diverse backgrounds. Children were assessed by their preschool teachers over two months with a standardized observational assessment instrument. A variety of latent trait models were used to test the developmental skill sequences of these learning strategies in relation to gender. Results revealed that variations in adult assistance and task complexity were related to the relative difficulty in performing these learning strategies. These findings support the notion that adult assistance can enhance the development of preschooler's self-regulated learning strategies. In particular, adult assistance promotes preschoolers' skills to perform simple functions independently and complex functions (e.g., advance planning or checking in parts) with adult help. Gender differences were found in preschoolers' difficulties in self-evaluating and seeking help. For example, females had more difficulty than males checking completed work with adult help and checking an activity in parts with adult help. Males had less difficulty checking a completed activity independently than females. Results also suggested that males are more sensitive to the presence of adult assistance when performing complex checking (i.e., checking in parts) than females. In addition, females were found to be more skilled than males in seeking assistance from adults in the classroom. No gender differences were found in goal setting and planning. The results from this study support the importance of social influences on preschoolers' development of self-regulated learning strategies. Future research directions and implications were also addressed.
    • 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.