Welcome to the UA Campus Repository, a service of the University of Arizona Libraries. The repository shares, archives and preserves unique digital materials from faculty, staff, students and affiliated contributors. Contact us at repository@u.library.arizona.edu with any questions.

 

Featured submissions

September 2020

August 2020

July 2020

  • The UA Campus Repository team is thrilled about the launch of our sister repository, ReDATA. To deposit research datasets and code, please use the newly created UA Research Data Repository (ReDATA). ReDATA will curate the data and provide a DOI upon publication. Access is currently by request only. To obtain access, please contact data-management@arizona.edu.
  • Deep Learning Classification of Chest X-Ray Images

    Majdi, Mohammad S.; Salman, Khalil N.; Morris, Michael F.; Merchant, Nirav C.; Rodriguez, Jeffrey J.; Univ Arizona, Dept Elect & Comp Engn; Univ Arizona, Dept Med Imaging; Univ Arizona, Data Sci Inst; Univ Arizona, Dept Radiol (IEEE, 2020-05-18)
    We propose a deep learning based method for classification of commonly occurring pathologies in chest X-ray images. The vast number of publicly available chest X-ray images provides the data necessary for successfully employing deep learning methodologies to reduce the misdiagnosis of thoracic diseases. We applied our method to the classification of two example pathologies, pulmonary nodules and cardiomegaly, and we compared the performance of our method to three existing methods. The results show an improvement in AUC for detection of nodules and cardiomegaly compared to the existing methods.
  • A history of recurrent, low-severity fire without fire exclusion in southeastern pine savannas, USA

    Rother, Monica T.; Huffman, Jean M.; Guiterman, Christopher H.; Robertson, Kevin M.; Jones, Neil; Univ Arizona, Lab Tree Ring Res (ELSEVIER, 2020-08-19)
    The reintroduction and maintenance of historical surface fire regimes are primary goals of ecological restoration across many open, pine-dominated ecosystems in North America. In the United States, most of these ecosystems experienced long periods of fire exclusion in the 20th century, leaving few locations to serve as reference sites for ecological conditions associated with a continuous history of recurrent, low-severity fire. Here, we present a tree-ring perspective of uninterrupted surface fire activity from three pine savanna sites in the Red Hills Region of northern Florida and southwestern Georgia, USA. Our sites include two old-growth stands of longleaf pine (Pinus palustris): the Wade Tract on Arcadia Plantation and the Larkin Tract on Millpond Plantation. We also sampled the largely second-growth mixed pine savannas of Tall Timbers Research Station. Documentary records for burning at these sites are limited to recent decades and are often incomplete, although regional land-use traditions and scattered historical records indicate frequent fire may have persisted through the 20th century to present day. Fire-scarred cross sections from externally-scarred stumps, dead trees, and live trees provided tree-ring evidence of frequent fires occurring from the beginning of our fire-scar record in the late 19th century onward. Both fire frequency and seasonality were relatively consistent throughout time and among sites. Biennial and annual fire intervals were the most common. Most fire scars occurred in the dormant and early-earlywood portions of the rings, indicating that these fires were human-set fires during the months of January to mid-April, before the main lightning-fire season. Our findings regarding post-settlement fire frequency are consistent with previous estimates of fire frequency during earlier centuries, resulting from lightning and Native American ignitions. We recommend that our sites be used as reference sites for restoration as they are among the relatively few areas in the United States with a continuous history of frequent low-severity fire without 20th century fire exclusion.
  • Ultimate causes of antipredator vocalizations in a nonhibernating squirrel

    Burnett, Alexandra D.; Koprowski, John L.; Univ Arizona, Sch Nat Resources & Environm (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2020-09-22)
    Communication plays an integral role in facilitating intra- and interspecific interactions. The study of signal function and content reveals the rules that govern such interactions, informing hypotheses in behavioural ecology and evolution. The ubiquitous nature of antipredator vocalizations in ground squirrels provides a useful model for studying the evolution of communication. Conspecifics in many ground squirrel species respond to anti-predator vocalizations, and sociality functions as a strong selective force favouring more informative antipredator vocalizations. However, studies of a single antipredator vocalization system in both social and nonsocial contexts are relatively scarce, preventing diagnosis of selective forces other than sociality. We conducted a 2-year study to test two alternative hypotheses relating to the function of antipredator vocalizations in a nonhibernating squirrel, the Harris' antelope squirrel, Ammospermophilus harristi. We hypothesized that if vocalizations function as a predator deterrent, callers should be of equal sex ratio and vocalize year-round. If vocalizations function primarily as a warning to offspring, callers should be predominantly female and vocalize only when juveniles are above ground. We found that spontaneous callers were predominantly female but vocalized throughout the year. We also found that call bouts varied in trill number, which could hold additional layers of information. Our results suggest that antipredator vocalizations function as both a predator deterrent and a warning to offspring. Antipredator vocalizations with multiple functions or receivers are subject to a greater compilation of selective forces that may induce communicative complexity to arise. (C) 2020 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
  • Dog cognitive development: a longitudinal study across the first 2 years of life

    Bray, Emily E; Gruen, Margaret E; Gnanadesikan, Gitanjali E; Horschler, Daniel J; Levy, Kerinne M; Kennedy, Brenda S; Hare, Brian A; MacLean, Evan L; Univ Arizona, Arizona Canine Cognit Ctr, Sch Anthropol; Univ Arizona, Cognit Sci Program; et al. (SPRINGER HEIDELBERG, 2020-10-28)
    While our understanding of adult dog cognition has grown considerably over the past 20 years, relatively little is known about the ontogeny of dog cognition. To assess the development and longitudinal stability of cognitive traits in dogs, we administered a battery of tasks to 160 candidate assistance dogs at 2 timepoints. The tasks were designed to measure diverse aspects of cognition, ranging from executive function (e.g., inhibitory control, reversal learning, memory) to sensory discrimination (e.g., vision, audition, olfaction) to social interaction with humans. Subjects first participated as 8-10-week-old puppies, and then were retested on the same tasks at similar to 21 months of age. With few exceptions, task performance improved with age, with the largest effects observed for measures of executive function and social gaze. Results also indicated that individual differences were both early emerging and enduring; for example, social attention to humans, use of human communicative signals, independent persistence at a problem, odor discrimination, and inhibitory control all exhibited moderate levels of rank-order stability between the two timepoints. Using multiple regression, we found that young adult performance on many cognitive tasks could be predicted from a set of cognitive measures collected in early development. Our findings contribute to knowledge about changes in dog cognition across early development as well as the origins and developmental stability of individual differences.
  • Brain site-specific regulation of hedonic intake by orexin and DYN peptides: role of the PVN and obesity

    Mattar, P; Uribe-Cerda, S; Pezoa, C; Guarnieri, T; Kotz, C M; Teske, J A; Morselli, E; Perez-Leighton, C; Univ Arizona, Dept Nutr Sci (TAYLOR & FRANCIS LTD, 2020-11-05)
    The orexin peptides promote hedonic intake and other reward behaviors through different brain sites. The opioid dynorphin peptides are co-released with orexin peptides but block their effects on reward in the ventral tegmental area (VTA). We previously showed that in the paraventricular hypothalamic nucleus (PVN), dynorphin and not orexin peptides enhance hedonic intake, suggesting they have brain-site-specific effects. Obesity alters the expression of orexin and dynorphin receptors, but whether their expression across different brain sites is important to hedonic intake is unclear. We hypothesized that hedonic intake is regulated by orexin and dynorphin peptides in PVN and that hedonic intake in obesity correlates with expression of their receptors. Here we show that in mice, injection of DYN-A1-13 (an opioid dynorphin peptide) in the PVN enhanced hedonic intake, whereas in the VTA, injection of OXA (orexin-A, an orexin peptide) enhanced hedonic intake. In PVN, OXA blunted the increase in hedonic intake caused by DYN-A1-13. In PVN, injection of norBNI (opioid receptor antagonist) reduced hedonic intake but a subsequent OXA injection failed to increase hedonic intake, suggesting that OXA activity in PVN is not influenced by endogenous opioid activity. In the PVN, DYN-A1-13 increased the intake of the less-preferred food in a two-food choice task. In obese mice fed a cafeteria diet, orexin 1 receptor mRNA across brain sites involved in hedonic intake correlated with fat preference but not caloric intake. Together, these data support that orexin and dynorphin peptides regulate hedonic intake in an opposing manner with brain-site-specific effects.

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