Now showing items 5571-5590 of 13760

    • Interleukin-1β Suppresses Gastrin via Primary Cilia and Induces Antral Hyperplasia

      Ding, L.; Sontz, E.A.; Saqui-Salces, M.; Merchant, J.L.; Department of Medicine-Gastroenterology, University of Arizona (Elsevier Inc., 2021)
      Background & Aims: Helicobacter pylori infection in humans typically begins with colonization of the gastric antrum. The initial Th1 response occasionally coincides with an increase in gastrin secretion. Subsequently, the gastritis segues to chronic atrophic gastritis, metaplasia, dysplasia and distal gastric cancer. Despite these well characterized clinical events, the link between inflammatory cytokines and non-cardia gastric cancer remains difficult to study in mouse models. Prior studies have demonstrated that overexpression of the Hedgehog (HH) effector GLI2 induces loss of gastrin (atrophy) and antral hyperplasia. To determine the link between specific cytokines, HH signaling and pre-neoplastic changes in the gastric antrum. Methods: Mouse lines were created to conditionally direct IL1β or IFN-γ to the antrum using the Gastrin-CreERT2 and Tet activator. Primary cilia, which transduces HH signaling, on G cells were disrupted by deleting the ciliary motor protein KIF3a. Phenotypic changes were assessed by histology and western blots. A subclone of GLUTag enteroendocrine cells selected for gastrin expression and the presence of primary cilia was treated with recombinant SHH, IL1β or IFN-γ with or without kif3a siRNA. Results: IFN-γ increased gastrin and induced antral hyperplasia. However, antral expression of IL1β suppressed tissue and serum gastrin, while also inducing antral hyperplasia. IFN-γ treatment of GLUTAg cells suppressed GLI2 and induced gastrin, without affecting cilia length. By contrast, IL1β treatment doubled primary cilia length, induced GLI2 and suppressed gastrin gene expression. Knocking down kif3a in GLUTAg cells mitigated SHH or IL1β suppression of gastrin. Conclusions: Overexpression of IL1β in the antrum was sufficient to induce antral hyperplasia coincident with suppression of gastrin via primary cilia. ORCID: #0000-0002-6559-8184 © 2021 The Authors
    • Intermediate Aerosol Loading Enhances Photosynthetic Activity of Croplands

      Wang, X.; Wang, C.; Wu, J.; Miao, G.; Chen, M.; Chen, S.; Wang, S.; Guo, Z.; Wang, Z.; Wang, B.; et al. (Blackwell Publishing Ltd, 2021)
      Aerosols can affect crop photosynthesis by altering radiation and meteorological conditions. By combining field observations, mechanistic modeling, and satellite-retrieved solar-induced chlorophyll fluorescence (SIF), we assessed aerosols' impacts on crop photosynthesis from leaf to regional scale. We found that the initial increase in aerosol optical depth (AOD) enhanced photosynthesis of sun leaves, shade leaves, and canopy, which reached their maximum at AOD = 0.76, 1.13, and 0.93, respectively, and then decreased. Aerosol-induced changes in radiation regime and the concurrent high relative humidity led to such nonlinear responses. Similarly, the SIF of croplands in the North China Plain (NCP) also showed a bell-shaped response to aerosols. The optimal AOD level at which SIF reached the maximum value varied from 0.56 to 1.04, depending on the background meteorological conditions. Approximately 76%–90% of the NCP exceeded the optimal AOD level, suggesting that stringent aerosol pollution control could promote cropland productivity in this region. © 2021. American Geophysical Union. All Rights Reserved.
    • Intermittency and the Value of Renewable Energy

      Gowrisankaran, Gautam; Reynolds, Stanley; Samano, Mario; Univ Arizona (UNIV CHICAGO PRESS, 2016-08)
      A key problem with solar energy is intermittency: solar generators produce only when the sun is shining, adding to social costs and requiring electricity system operators to reoptimize key decisions. We develop a method to quantify the economic value of large-scale renewable energy. We estimate the model for southeastern Arizona. Not accounting for offset carbon dioxide, we find social costs of $138.40 per megawatt hour for 20 percent solar generation, of which unforecastable intermittency accounts for $6.10 and intermittency overall for $46.00. With solar installation costs of $1.52 per watt and carbon dioxide social costs of $39.00 per ton, 20 percent solar would be welfare neutral.
    • Internal Hernia Masquerading As Necrotizing Enterocolitis

      Kylat, Ranjit I.; Univ Arizona, Coll Med, Dept Pediat (FRONTIERS MEDIA SA, 2017-10-31)
      In extremely preterm infants, acute abdominal emergencies are fortunately less common with improving care. Spontaneous intestinal perforation and necrotizing enterocolitis are conditions where emergency surgery is most often needed. Conservative medical management and placement of temporary drain are often used in the initial management. Internal hernia (IH) is an uncommon cause of bowel obstruction in neonates, is difficult to diagnose and unfortunately are found only at autopsy. The presentation in preterm infants, distinction between these conditions, and the need for early diagnosis of IH are discussed.
    • Internal ocean-atmosphere variability drives megadroughts in Western North America

      Coats, S.; Smerdon, J. E.; Cook, B. I.; Seager, R.; Cook, E. R.; Anchukaitis, Kevin J.; Univ Arizona, Sch Geog & Dev; Univ Arizona, Tree Ring Res Lab; Cooperative Institute for Research in Environmental Sciences; University of Colorado Boulder; Boulder Colorado USA; Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA; et al. (AMER GEOPHYSICAL UNION, 2016-09-28)
      Multidecadal droughts that occurred during the Medieval Climate Anomaly represent an important target for validating the ability of climate models to adequately characterize drought risk over the near-term future. A prominent hypothesis is that these megadroughts were driven by a centuries-long radiatively forced shift in the mean state of the tropical Pacific Ocean. Here we use a novel combination of spatiotemporal tree ring reconstructions of Northern Hemisphere hydroclimate to infer the atmosphere-ocean dynamics that coincide with megadroughts over the American West and find that these features are consistently associated with 10-30 year periods of frequent cold El Nino-Southern Oscillation conditions and not a centuries-long shift in the mean of the tropical Pacific Ocean. These results suggest an important role for internal variability in driving past megadroughts. State-of-the-art climate models from the Coupled Model Intercomparison Project Phase 5, however, do not simulate a consistent association between megadroughts and internal variability of the tropical Pacific Ocean, with implications for our confidence in megadrought risk projections.
    • Internal States Influence the Representation and Modulation of Food Intake by Subthalamic Neurons

      Wu, Haichuan; Yan, Xiang; Tang, Dongliang; Gu, Weixin; Luan, Yiwen; Cai, Haijiang; Zhou, Chunyi; Xiao, Cheng; Univ Arizona, Dept Neurosci (SPRINGER, 2020-06-21)
      Deep brain stimulation of the subthalamic nucleus (STN) is an effective therapy for motor deficits in Parkinson's disease (PD), but commonly causes weight gain in late-phase PD patients probably by increasing feeding motivation. It is unclear how STN neurons represent and modulate feeding behavior in different internal states. In the present study, we found that feeding caused a robust activation of STN neurons in mice (GCaMP6 signal increased by 48.4% +/- 7.2%, n= 9, P= 0.0003), and the extent varied with the size, valence, and palatability of food, but not with the repetition of feeding. Interestingly, energy deprivation increased the spontaneous firing rate (8.5 +/- 1.5 Hz, n= 17, versus 4.7 +/- 0.7 Hz, n= 18, P= 0.03) and the depolarization-induced spikes in STN neurons, as well as enhanced the STN responses to feeding. Optogenetic experiments revealed that stimulation and inhibition of STN neurons respectively reduced (by 11% +/- 6%,n= 6,P= 0.02) and enhanced (by 36% +/- 15%, n= 7, P= 0.03) food intake only in the dark phase. In conclusion, our results support the hypothesis that STN neurons are activated by feeding behavior, depending on energy homeostatic status and the palatability of food, and modulation of these neurons is sufficient to regulate food intake.
    • International Clostridium difficile animal strain collection and large diversity of animal associated strains

      Janezic, Sandra; Zidaric, Valerija; Pardon, Bart; Indra, Alexander; Kokotovic, Branko; Blanco, Jose; Seyboldt, Christian; Diaz, Cristina; Poxton, Ian; Perreten, Vincent; et al. (BioMed Central, 2014)
      BACKGROUND:Clostridium difficile is an important cause of intestinal infections in some animal species and animals might be a reservoir for community associated human infections. Here we describe a collection of animal associated C. difficile strains from 12 countries based on inclusion criteria of one strain (PCR ribotype) per animal species per laboratory.RESULTS:Altogether 112 isolates were collected and distributed into 38 PCR ribotypes with agarose based approach and 50 PCR ribotypes with sequencer based approach. Four PCR ribotypes were most prevalent in terms of number of isolates as well as in terms of number of different host species: 078 (14.3% of isolates
    • The International Deep Planet Survey

      Galicher, R.; Marois, C.; Macintosh, B.; Zuckerman, B.; Barman, T.; Konopacky, Q.; Song, I.; Patience, J.; Lafrenière, D.; Doyon, R.; et al. (EDP SCIENCES S A, 2016-10-13)
      Context. Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. Aims. We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. Methods. We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 yr. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. Results. The main result of the international deep planet survey is the discovery of the HR8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05(-0.70)(+2.80)% of stars harbor at least one giant planet between 0.5 and 14 MJ and between 20 and 300AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30(-1.55)(+5.95)%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. Conclusions. The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works.
    • International Graduate Student Labor as Mergers and Acquisitions

      Cantwell, Brendan; Lee, Jenny J.; Mlambo, Yeukai A.; Univ Arizona, Ctr Study Higher Educ (UNIV LOUISIANA MONROE, 2018-10-22)
      This study critically examines the self-reported experiences of international graduate students using a framework understanding internationalization as acquisitions and mergers. Students reported positive experiences with their advisors. However, students' accounts of laboratories and other research settings were diverse, ranging from co-contributors to knowledge and respected collaborators to employed cheap labor that their advisors depended upon for their own gains. In some cases, these students feared that their funding would be cut off or dismissed from the program (and consequently deported from the US) if they challenged their advisors. Whether such apprehensions were valid is unknown as this study focused on perceptions of the students only. The findings do lead to important future directions for research and practice.
    • International river basin organizations, science, and hydrodiplomacy

      Milman, Anita; Gerlak, Andrea K.; Univ Arizona, Sch Geog & Dev; Univ Arizona, Udall Ctr Studies Publ Policy (ELSEVIER SCI LTD, 2020-05)
      As key venues for interaction and cooperation, international river basin organizations (IRBOs) are significant contributors to hydro-diplomacy in transboundary river basins. As part of their efforts to support hydrodiplomacy, IRBOs engage in the production and use of science. The manner in which that science is produced, and how it contributes to hydrodiplomacy, is not well understood. This paper examines the production and use of science by three IRBOs: the (US - Canada) International Joint Commission, the International Commission for the Protection of the Danube River, and the Mekong River Commission. We find the science produced by the IRBOs to support hydrodiplomacy extends beyond measuring and monitoring to include more advanced and analytical forms of science. In producing science, we observe that the IRBOs balance considerations of capacity, ownership, and how the politics of the basin will influence the production and use of the science. Given the challenge of balancing across these considerations, future research is needed to determine what mechanisms and processes for producing science can best facilitate its use in hydrodiplomacy.
    • International Students Seeking Political Stability and Safety in South Africa

      Lee, Jenny J.; Sehoole, Chika; Univ Arizona, Ctr Study Higher Educ (PALGRAVE MACMILLAN LTD, 2020-06)
      Given the increasing rate of South to South migration and South Africa's leading role as a host for internally displaced migrants as well as Africa's international students, this study examined this intersection of international students who selected the country for political stability and safety. The findings revealed that while these students were generally more highly prepared academically, more satisfied with university facilities and staff, and experienced fewer academic hurdles than their international student counterparts, they encountered greater challenges in regard to finances, living support and discrimination. The study calls for clearer acknowledgement in policy and specialized support for refugee and asylum seekers' unique situations and needs.
    • Internet of Samples (iSamples): Toward an interdisciplinary cyberinfrastructure for material samples

      Davies, N.; Deck, J.; Kansa, E.C.; Kansa, S.W.; Kunze, J.; Meyer, C.; Orrell, T.; Ramdeen, S.; Snyder, R.; Vieglais, D.; et al. (Oxford University Press, 2021)
      Sampling the natural world and built environment underpins much of science, yet systems for managing material samples and associated (meta)data are fragmented across institutional catalogs, practices for identification, and discipline-specific (meta)data standards. The Internet of Samples (iSamples) is a standards-based collaboration to uniquely, consistently, and conveniently identify material samples, record core metadata about them, and link them to other samples, data, and research products. iSamples extends existing resources and best practices in data stewardship to render a cross-domain cyberinfrastructure that enables transdisciplinary research, discovery, and reuse of material samples in 21st century natural science. © The Author(s) 2021. Published by Oxford University Press GigaScience.
    • Interns Shall Not Sleep: The Duty Hours Boomerang

      Quan, Stuart F; Asthma and Airways Research Center, University of Arizona College of Medicine, Tucson, AZ; Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (Arizona Thoracic Society, 2017-04-03)
      Editorial regarding the recently announced change in resident duty hours
    • Interoceptive Insular Cortex Mediates Both Innate Fear and Contextual Threat Conditioning to Predator Odor

      Rodríguez, María; Ceric, Francisco; Murgas, Paola; Harland, Bruce; Torrealba, Fernando; Contreras, Marco; Univ Arizona, Dept Psychol (FRONTIERS MEDIA SA, 2020-01-09)
      The insular cortex (IC), among other brain regions, becomes active when humans experience fear or anxiety. However, few experimental studies in rats have implicated the IC in threat responses. We have recently reported that inactivation of the primary interoceptive cortex (pIC) during pre-training, or the intra-pIC blockade of protein synthesis immediately after training, impaired the consolidation of auditory fear conditioning. The present study was designed to investigate the role of the pIC in innate and learned defensive responses to predator odor. Freezing behavior was elicited by single or repetitive exposures to a collar that had been worn by a domestic cat. Sessions were video-recorded and later scored by video observation. We found that muscimol inactivation of the pIC reduced the expression of freezing reaction in response to a single or repeated exposure to cat odor. We also found that pIC inactivation with muscimol impaired conditioning of fear to the context in which rats were exposed to cat odor. Furthermore, neosaxitoxin inactivation of the pIC resulted in a prolonged and robust reduction in freezing response in subsequent re-exposures to cat odor. In addition, freezing behavior significantly correlated with the neural activity of the IC. The present results suggest that the IC is involved in the expression of both innate and learned fear responses to predator odor.
    • Interorganizational trust production contingent on product and performance uncertainty

      Schilke, Oliver; Wiedenfels, Gunnar; Brettel, Malte; Zucker, Lynne G.; The University of Arizona (OXFORD UNIV PRESS, 2016-08-11)
      How do organizations build trust under varying degrees of uncertainty? In this article, we propose that different degrees of uncertainty require different bases of trust. We distinguish between three different forms of trust production (process-based, characteristics-based and institution-based) and develop hypotheses regarding their relative effectiveness under low versus high levels of product and performance uncertainty. Using survey data on 392 interorganizational buyer-seller relationships, we find support for our position that a high degree of uncertainty favours process-based trust production, whereas characteristics-based trust production is relatively more effective when uncertainty is low. The effectiveness of institution-based trust production is not significantly affected by uncertainty. We derive implications for organizational trust production under different degrees of uncertainty, which should encourage new research on trust.
    • Interpersonal comparisons with preferences and desires

      Barrett, Jacob; Univ Arizona, Dept Philosophy (SAGE PUBLICATIONS INC, 2019-08-13)
      Most moral and political theories require us to make interpersonal comparisons of welfare. This poses a challenge to the popular view that welfare consists in the satisfaction of preferences or desires, because interpersonal comparisons of preference or desire satisfaction are widely thought to be conceptually problematic, and purported solutions to this problem to lead to a hopeless subjectivism about these comparisons. In this article, I argue that the key to meeting this challenge lies in distinguishing preferences from desires, and preference satisfaction from desire satisfaction theories of welfare. More specifically, I defend three conclusions. First, interpersonal comparisons of preference satisfaction do raise a serious conceptual problem, but this same problem does not arise for interpersonal comparisons of desire satisfaction. Second, none of the existing solutions to the conceptual problem of interpersonal comparisons of preference satisfaction are satisfactory, since none explain how we can make interpersonal comparisons of preference satisfaction objectively. Third, we can at least make a limited range of objective interpersonal comparisons of desire satisfaction, and there are reasons to be optimistic about the possibility of making a wider range of such comparisons, but there is a need for further research on the topic.
    • Interpersonal conflict over water is associated with household demographics, domains of water insecurity, and regional conflict: Evidence from nine sites across eight sub-saharan african countries

      Pearson, A.L.; Mack, E.A.; Ross, A.; Marcantonio, R.; Zimmer, A.; Bunting, E.L.; Smith, A.C.; Miller, J.D.; Evans, T.; Collins, S.M.; et al. (MDPI AG, 2021)
      Water insecurity may precipitate interpersonal conflict, although no studies to date have rigorously examined these relationships. We examined relationships between household demograph-ics, water insecurity, regional conflict, and interpersonal conflict over water. Using survey data from eight sub-Saharan African countries, we found that interpersonal conflict within and outside the home is associated with multiple domains of water insecurity, particularly accessibility. Further-more, we found that higher levels of remote violence and protests are associated with greater within household conflict, whereas riots and violent armed conflict are associated with greater conflict between neighbors. Our findings expand upon the current literature by examining factors affecting interpersonal conflict over water, which may become increasingly important as precipitation patterns and land temperatures change in this region. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • Interpersonal Focus in the Emotional Autobiographical Memories of Older and Younger Adults

      Polsinelli, Angelina J.; Rentscher, Kelly E.; Glisky, Elizabeth L.; Moseley, Suzanne A.; Mehl, Matthias R.; Univ Arizona, Psychol Dept (HOGREFE & HUBER PUBLISHERS, 2020-03)
      The present study examined the interpersonal focus within autobiographical memories (AMs) of older and younger adults from the perspective of socioemotional selectivity theory (SST). Specifically, we measured interpersonal focus directly through rater codings (relational vs. individual focus) and social word use, and indirectly through personal pronoun use. Forty-five older (M-age = 76.76) and 25 younger (M-age = 18.64) adults recalled positive and negative AMs, which were then coded and processed through computerized text analysis software to obtain word-use counts. Consistent with SST, the positive AMs of older adults were more interpersonally focused compared to negative AMs and younger adults. The results suggest that the positive life experiences of older adults tend to be associated with a high degree of social importance and focus on others.
    • THE INTERPLANETARY NETWORK RESPONSE TO LIGO GW150914

      Hurley, K.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Boynton, W.; Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; et al. (IOP PUBLISHING LTD, 2016-09-19)
      We have performed a blind search for a gamma-ray transient of arbitrary duration and energy spectrum around the time of the LIGO gravitational-wave event GW150914 with the six-spacecraft interplanetary network (IPN). Four gamma-ray bursts were detected between 30 hr prior to the event and 6.1 hr after it, but none could convincingly be associated with GW150914. No other transients were detected down to limiting 15-150 keV fluences of roughly 5 x10-(8) -5 x 10(-7) erg cm(-2). We discuss the search strategies and temporal coverage of the IPN on the day of the event and compare the spatial coverage to the region where GW150914 originated. We also report the negative result of a targeted search for the Fermi-GBM event reported in conjunction with GW150914.
    • Interplay between intermittency and dissipation in collisionless plasma turbulence

      Mallet, Alfred; Klein, Kristopher G.; Chandran, Benjamin D. G.; Grošelj, Daniel; Hoppock, Ian W.; Bowen, Trevor A.; Salem, Chadi S.; Bale, Stuart D.; Univ Arizona, Lunar & Planetary Lab (CAMBRIDGE UNIV PRESS, 2019-06-14)
      We study the damping of collisionless Alfvenic turbulence in a strongly magnetised plasma by two mechanisms: stochastic heating (whose efficiency depends on the local turbulence amplitude delta z(lambda)) and linear Landau damping (whose efficiency is independent of delta z(lambda)), describing in detail how they affect and are affected by intermittency. The overall efficiency of linear Landau damping is not affected by intermittency in critically balanced turbulence, while stochastic heating is much more efficient in the presence of intermittent turbulence. Moreover, stochastic heating leads to a drop in the scale-dependent kurtosis over a narrow range of scales around the ion gyroscale.