Now showing items 12840-12859 of 13755

    • Too Busy to Be Manipulated: How Multitasking with Technology Improves Deception Detection in Collaborative Teamwork

      Twyman, Nathan W.; Proudfoot, Jeffrey G.; Cameron, Ann-Frances; Case, Eric; Burgoon, Judee K.; Twitchell, Douglas P.; Univ Arizona, Ctr Management Informat, Eller Coll Management (ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2020-04-02)
      Deception is an unfortunate staple in group work. Guarding against team members' deceptive tactics and alternative agendas is difficult and may seem even more difficult in technology-driven business environments that have made multitasking during teamwork increasingly commonplace. This research develops a foundation for a nuanced theoretical understanding of deception detection under these conditions. The intersection of information technology multitasking and deception detection theories is shown to produce various and sometimes competing ideas about how this type of multitasking might affect truthfulness assessments in real-time teamwork. A laboratory study involving a collaborative game helped evaluate the different ideas using manipulated deception and multitasking behaviors in a real-time, virtual group environment. The results provide evidence that information multitasking can actually improve deception detection, likely because multitaskers engage less in the team conversation, making themselves less manipulable. As understanding of multitasking benefits increases, managers and designers can incorporate effective multitasking into collaborative processes.
    • Too Many Hats? Conflicts of Interest in Learning Community Faculty Roles

      Gliatto, Peter; Colbert-Getz, Jorie M; Bhutiani, Monica; Cutrer, William B; Edwards, Sharon; Fleming, Amy; Keeley, Meg; Osterberg, Lars; Pilla, Michael A; Moynahan, Kevin; et al. (SAGE PUBLICATIONS LTD, 2019-03-22)
      PURPOSE: Many US medical schools have adopted learning communities to provide a framework for advising and teaching functions. Faculty who participate in learning communities often have additional educator roles. Defining potential conflicts of interest (COIs) among these roles is an important consideration for schools with existing learning communities and those looking to develop them, both for transparency with students and also to comply with regulatory requirements. METHODS: A survey was sent to the institutional contact for each of the 42 Learning Communities Institute (LCI) member medical schools to assess faculty opinions about what roles potentially conflict. The survey asked the role of learning community faculty in summative and formative assessment of students and whether schools had existing policies around COIs in medical education. RESULTS : In all, 35 (85%) LCI representatives responded; 30 (86%) respondents agreed or strongly agreed that learning community faculty should be permitted to evaluate their students for formative purposes, while 19 (54%) strongly agreed or agreed that learning community faculty should be permitted to evaluate their students in a way that contributes to a grade; 31 (89%) reported awareness of the accreditation standard ensuring " that medical students can obtain academic counseling from individuals who have no role in making assessment or promotion decisions about them," but only 10 (29%) had a school policy about COIs in education. There was a wide range of responses about what roles potentially conflict with being a learning community faculty. CONCLUSION: The potential for COIs between learning community faculty and other educator roles concerns faculty at schools with learning communities, but most schools have not formally addressed these concerns.
    • Too much of a good thing? A landscape-of-fear analysis for collared peccaries (Pecari tajacu) reveals hikers act as a greater deterrent than thorny or bitter food

      Bleicher, Sonny S.; Rosenzweig, Michael L.; Univ Arizona, Dept Ecol & Evolutionary Biol (CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS, 2018-04)
      To study how wildlife perceive recreating humans, we studied the habitat selection of a human commensalist, the collared peccary (Pecari tajacu (Linnaeus, 1758)). We measured peccary activity patterns in an area of high human activity (Tumamoc Hill Desert Laboratory in Tucson, Arizona, USA) using a landscape-of-fear analysis. We examined whether the perception of risk from human activity interacted with the chemical (tannin) and mechanical (thorns) antipredator mechanisms of local plant species. The peccaries avoided food stations near a hiking trail. The population foraged less near houses, i.e., moderate human activity, than in the perceived safety of a small wadi. Plant defence treatments impacted the harvesting of food only in the safe zone, suggesting that risk trumps food selectivity. The strong effect of the hiking trail on habitat selection in this disturbance-loving species is an indicator of a much larger impact on sensitive species in conservation areas.
    • The topic of imprisonment in medieval literature. With an emphasis on Johann Schiltberger’s account about his 30-year enslavement in the East

      Classen, Albrecht; Univ Arizona, Dept German Studies (ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2020-04-21)
      One of the dramatic, if not traumatic, experiences in life has always been enslavement and imprisonment, that is, the loss of personal freedom, and this for many different reasons. Curiously, medieval literature does not seem to address this topic extensively, at least at first sight, and research has paid rather little attention to this issue. A close analysis, however, demonstrates quickly that the theme of imprisonment was of significant concern throughout the Middle Ages, probably because the loss of individual freedom happened more often than not and could also affect members of the nobility. There were many cases of imprisonment as a result of criminal activities, sometimes also committed by knights or noble ladies. Worst, however, was the experience of those who were taken as captives after a battle and then were enslaved. This article provides a first framework for the study of this large topic in pre-modern literature and so-called ego-documents and then focuses on a most dramatic example, the report by the long-term slave Johannes Schiltberger.
    • Topical Bixin Confers NRF2-Dependent Protection Against Photodamage and Hair Graying in Mouse Skin

      Rojo de la Vega, Montserrat; Zhang, Donna D; Wondrak, Georg T; Univ Arizona, Coll Pharm, Dept Pharmacol & Toxicol (FRONTIERS MEDIA SA, 2018-03-27)
      Environmental exposure to solar ultraviolet (UV) radiation causes acute photodamage, premature aging, and skin cancer, attributable to UV-induced genotoxic, oxidative, and inflammatory stress. The transcription factor NRF2 [nuclear factor erythroid 2 (E2)-related factor 2] is the master regulator of the cellular antioxidant response protecting skin against various environmental stressors including UV radiation and electrophilic pollutants. NRF2 in epidermal keratinocytes can be activated using natural chemopreventive compounds such as the apocarotenoid bixin, an FDA-approved food additive and cosmetic ingredient from the seeds of the achiote tree (Bixa orellana). Here, we tested the feasibility of topical use of bixin for NRF2-dependent skin photoprotection in two genetically modified mouse models [SKH1 and C57BL/6J (Nrf2(+/+) versus Nrf2(-/-))]. First, we observed that a bixin formulation optimized for topical NRF2 activation suppresses acute UV-induced photodamage in Nrf2(+/+) but not Nrf2(-/-) SKH1 mice, a photoprotective effect indicated by reduced epidermal hyperproliferation and oxidative DNA damage. Secondly, it was demonstrated that topical bixin suppresses PUVA (psoralen + UVA)-induced hair graying in Nrf2(+/+) but not Nrf2(-/-) C57BL/6J mice. Collectively, this research provides the first in vivo evidence that topical application of bixin can protect against UV-induced photodamage and PUVA-induced loss of hair pigmentation through NRF2 activation. Topical NRF2 activation using bixin may represent a novel strategy for human skin photoprotection, potentially complementing conventional sunscreen-based approaches.
    • The Topographic Signature of Ecosystem Climate Sensitivity in the Western United States

      Hoylman, Zachary H.; Jencso, Kelsey G.; Hu, Jia; Holden, Zachary A.; Allred, Brady; Dobrowski, Solomon; Robinson, Nathaniel; Martin, Justin T.; Affleck, David; Seielstad, Carl; et al. (AMER GEOPHYSICAL UNION, 2019-12-23)
      It has been suggested that hillslope topography can produce hydrologic refugia, sites where ecosystem productivity is relatively insensitive to climate variation. However, the ecological impacts and spatial distribution of these sites are poorly resolved across gradients in climate. We quantified the response of ecosystem net primary productivity to changes in the annual climatic water balance for 30 years using pixel-specific linear regression (30-m resolution) across the western United States. The standardized slopes of these models represent ecosystem climate sensitivity and provide a means to identify drought-resistant ecosystems. Productive and resistant ecosystems were most frequent in convergent hillslope positions, especially in semiarid climates. Ecosystems in divergent positions were moderately resistant to climate variability, but less productive relative to convergent positions. This topographic effect was significantly dampened in hygric and xeric climates. In aggregate, spatial patterns of ecosystem sensitivity can be implemented for regional planning to maximize conservation in landscapes more resistant to perturbations.
    • Topographically driven differences in energy and water constrain climatic control on forest carbon sequestration

      Swetnam, Tyson L.; Brooks, Paul D.; Barnard, Holly R.; Harpold, Adrian A.; Gallo, Erika L.; Univ Arizona, Inst BIO5; Univ Arizona, Dept Hydrol & Water Resources; BIO5 Institute; University of Arizona; 1657 E Helen Street Tucson Arizona 85721 USA; Department of Geology and Geophysics; University of Utah; Frederick Albert Sutton Building, 115 S 1460 E 383 Salt Lake City Utah 84112 USA; Department of Geography and INSTAAR; University of Colorado; Guggenheim 110, 260 UCB Boulder Colorado 80309 USA; et al. (WILEY, 2017-04)
      Mountains are vital to ecosystems and human society given their influence on global carbon and water cycles. Yet the extent to which topography regulates montane forest carbon uptake and storage remains poorly understood. To address this knowledge gap, we compared forest aboveground carbon loading to topographic metrics describing energy balance and water availability across three headwater catchments of the Boulder Creek Watershed, Colorado, USA. The catchments range from 1800 to 3500 m above mean sea level with 46-102 cm/yr mean annual precipitation and -1.2 degrees to 12.3 degrees C mean annual temperature. In all three catchments, we found mean forest carbon loading consistently increased from ridges (27 +/- 19 Mg C ha) to valley bottoms (60 +/- 28 Mg C ha). Low topographic positions held up to 185 +/- 76 Mg C ha, more than twice the peak value of upper positions. Toe slopes fostered disproportionately high net carbon uptake relative to other topographic positions. Carbon storage was on average 20-40 Mg C ha greater on north to northeast aspects than on south to southwest aspects, a pattern most pronounced in the highest elevation, coldest and wettest catchment. Both the peak and mean aboveground carbon storage of the three catchments, crossing an 11 degrees C range in temperature and doubling of local precipitation, defied the expectation of an optimal elevation-gradient climatic zone for net primary production. These results have important implications for models of forest sensitivity to climate change, as well as to predicted estimates of continental carbon reservoirs.
    • Topological actions via gauge variations of higher structures

      Sati, Hisham; Wheeler, Matthew; Univ Arizona, Dept Math (ELSEVIER SCIENCE BV, 2019-02-10)
      In this note we provide a new perspective on the topological parts of several action functionals in string and M-theory. We show that rationally these can be viewed as large gauge transformations corresponding to variations of higher structures, such as String, Fivebrane, and Ninebrane structures. (C) 2018 The Author(s). Published by Elsevier B.V.
    • Topological properties of coupled one-dimensional chains of elastic rotators

      Deymier, P.A.; Runge, K.; Hasan, M.A.; Department of Materials Science and Engineering, University of Arizona (American Institute of Physics Inc., 2021)
      We introduce a model system composed of elastically coupled one-dimensional chains of elastic rotators. The chains of rotators are analogous to elastic Su-Schrieffer-Heeger models. The coupled chain system is shown analytically and numerically to support an unusual number of topological properties such as Dirac degeneracies, band inversion and topological transition as a function of the strength of the parameter coupling the chains, nonseparability of the modes' degrees of freedom along and across the coupled chains that are analogous to entangled Bell states in a multipartite quantum system. Finally, we reveal the formation of a synthetic dimension by allowing the coupling parameter to vary with time, which has the potential to create higher-dimensional synthetic space. © 2021 Author(s).
    • Topologically Protected Helical States in Minimally Twisted Bilayer Graphene

      Huang, Shengqiang; Kim, Kyounghwan; Efimkin, Dmitry K.; Lovorn, Timothy; Taniguchi, Takashi; Watanabe, Kenji; MacDonald, Allan H.; Tutuc, Emanuel; LeRoy, Brian J.; Univ Arizona, Phys Dept (AMER PHYSICAL SOC, 2018-07-17)
      In minimally twisted bilayer graphene, a moire pattern consisting of AB and BA stacking regions separated by domain walls forms. These domain walls are predicted to support counterpropogating topologically protected helical (TPH) edge states when the AB and BA regions are gapped. We fabricate designer moire crystals with wavelengths longer than 50 nm and demonstrate the emergence of TPH states on the domain wall network by scanning tunneling spectroscopy measurements. We observe a double-line profile of the TPH states on the domain walls, only occurring when the AB and BA regions are gapped. Our results demonstrate a practical and flexible method for TPH state network construction.
    • The Topology ToolKit

      Tierny, Julien; Favelier, Guillaume; Levine, Joshua A.; Gueunet, Charles; Michaux, Michael; Univ Arizona (IEEE COMPUTER SOC, 2018-01)
      This system paper presents the Topology ToolKit (TTK), a software platform designed for the topological analysis of scalar data in scientific visualization. While topological data analysis has gained in popularity over the last two decades, it has not yet been widely adopted as a standard data analysis tool for end users or developers. TTK aims at addressing this problem by providing a unified, generic, efficient, and robust implementation of key algorithms for the topological analysis of scalar data, including: critical points, integral lines, persistence diagrams, persistence curves, merge trees, contour trees, Morse-Smale complexes, fiber surfaces, continuous scatterplots, Jacobi sets, Reeb spaces, and more. TTK is easily accessible to end users due to a tight integration with ParaView. It is also easily accessible to developers through a variety of bindings (Python, VTK/C++) for fast prototyping or through direct, dependency-free, C++, to ease integration into pre-existing complex systems. While developing TTK, we faced several algorithmic and software engineering challenges, which we document in this paper. In particular, we present an algorithm for the construction of a discrete gradient that complies to the critical points extracted in the piecewise-linear setting. This algorithm guarantees a combinatorial consistency across the topological abstractions supported by TTK, and importantly, a unified implementation of topological data simplification for multi-scale exploration and analysis. We also present a cached triangulation data structure, that supports time efficient and generic traversals, which self-adjusts its memory usage on demand for input simplicial meshes and which implicitly emulates a triangulation for regular grids with no memory overhead. Finally, we describe an original software architecture, which guarantees memory efficient and direct accesses to TTK features, while still allowing for researchers powerful and easy bindings and extensions. TTK is open source (BSD license) and its code, online documentation and video tutorials are available on TTK's website [108].
    • TormodGillies_MF_2008

      Carnie, Andrew H.; University of Arizona; Tormod Gillies; Muriel Fisher (2016)
    • Total artificial heart implantation in a young Marfan syndrome patient

      Rao, Prashant; Keenan, Jack B; Rajab, Taufiek K; Kim, Samuel; Smith, Richard; Amabile, Orazio; Khalpey, Zain; Univ Arizona, Sarver Heart Ctr, Coll Med; Univ Arizona, Coll Med, Dept Surg, Div Cardiothorac Surg (SAGE PUBLICATIONS LTD, 2018-03)
      Introduction: Cardiovascular complications represent the leading cause of morbidity and mortality in patients with Marfan syndrome. Here, we describe a unique case where a total artificial heart was implanted in a young Marfan syndrome woman. Methods: A 22-year-old postpartum African American female with Marfan syndrome developed multiple severe valve dysfunction and biventricular failure that was refractory to medical management. She previously had a Bentall procedure for Type A aortic dissection and repair of a Type B dissection. Results: We implanted a total artificial heart with a good outcome. Conclusion: Total artificial heart is a durable option for severe biventricular failure and multiple valvular dysfunction as a bridge to transplant in a young patient with Marfan syndrome.
    • Total Long-Chain n-3 Fatty Acid Intake and Food Sources in the United States Compared to Recommended Intakes: NHANES 2003–2008

      Richter, Chesney K.; Bowen, Kate J.; Mozaffarian, Dariush; Kris-Etherton, Penny M.; Skulas-Ray, Ann C.; Univ Arizona, Dept Nutr Sci; Univ Arizona, Arizona Ctr Aging (SPRINGER HEIDELBERG, 2017-09-27)
      The American Heart Association recommends consuming fish (particularly oily fish) at least two times per week, which would provide ae 0.5 g/day of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) for cardiovascular disease risk reduction. Previous analyses indicate that this recommendation is not being met; however, few studies have assessed different ethnicities, subpopulations requiring additional n-3 fatty acid intake (i.e., children and pregnant and/or lactating women), or deciles of intake. Data from the National Health and Nutrition Examination Survey 2003-2008 was used to assess n-3 fatty acid intake from foods and supplements in the US population, according to age, sex, and ethnicity. A unique "EPA equivalents" factor, which accounts for potential conversion of shorter-chain n-3 fatty acids, was used to calculate total long-chain n-3 fatty acid intake. Data are reported for 24,621 individuals. More than 90% consumed less than the recommended 0.5 g/day from food sources (median = 0.11 g/day; mean = 0.17 g/day). Among the top 15% of n-3 fatty acid consumers, fish was the largest dietary contributor (71.2%). Intake was highest in men aged 20 years or more, and lowest in children and women who are or may become pregnant and/or are lactating. Among ethnicities, intake was lowest in Mexican-Americans. Only 6.2% of the total population reported n-3 fatty acid supplement use, and this did not alter median daily intake. Additional strategies are needed to increase awareness of health benefits (particularly among Mexican-Americans and women of childbearing age) and promote consumption of oily fish or alternative dietary sources to meet current recommendations.
    • Total organic carbon and the contribution from speciated organics in cloud water: Airborne data analysis from the CAMP2Ex field campaign

      Stahl, C.; Crosbie, E.; Bañaga, P.A.; Betito, G.; Braun, R.A.; Cainglet, Z.M.; Cambaliza, M.O.; Cruz, M.T.; Dado, J.M.; Hilario, M.R.A.; et al. (Copernicus GmbH, 2021)
      This work focuses on total organic carbon (TOC) and contributing species in cloud water over Southeast Asia using a rare airborne dataset collected during NASA's Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex), in which a wide variety of maritime clouds were studied, including cumulus congestus, altocumulus, altostratus, and cumulus. Knowledge of TOC masses and their contributing species is needed for improved modeling of cloud processing of organics and to understand how aerosols and gases impact and are impacted by clouds. This work relies on 159 samples collected with an axial cyclone cloud-water collector at altitudes of 0.2-6.8ĝ€¯km that had sufficient volume for both TOC and speciated organic composition analysis. Species included monocarboxylic acids (glycolate, acetate, formate, and pyruvate), dicarboxylic acids (glutarate, adipate, succinate, maleate, and oxalate), methanesulfonic acid (MSA), and dimethylamine (DMA). TOC values range between 0.018 and 13.66ĝ€¯ppmĝ€¯C with a mean of 0.902ĝ€¯ppm C. The highest TOC values are observed below 2ĝ€¯km with a general reduction aloft. An exception is samples impacted by biomass burning for which TOC remains enhanced at altitudes as high as 6.5ĝ€¯km (7.048ĝ€¯ppmĝ€¯C). Estimated total organic matter derived from TOC contributes a mean of 30.7ĝ€¯% to total measured mass (inorganics + organics). Speciated organics contribute (on a carbon mass basis) an average of 30.0ĝ€¯% to TOC in the study region and account for an average of 10.3ĝ€¯% to total measured mass. The order of the average contribution of species to TOC, in decreasing contribution of carbon mass, is as follows (±1 standard deviation): acetate (14.7ĝ€¯±ĝ€¯20.5ĝ€¯%), formate (5.4ĝ€¯±ĝ€¯9.3ĝ€¯%), oxalate (2.8ĝ€¯±ĝ€¯4.3ĝ€¯%), DMA (1.7ĝ€¯±ĝ€¯6.3ĝ€¯%), succinate (1.6ĝ€¯±ĝ€¯2.4ĝ€¯%), pyruvate (1.3ĝ€¯±ĝ€¯4.5ĝ€¯%), glycolate (1.3ĝ€¯±ĝ€¯3.7ĝ€¯%), adipate (1.0ĝ€¯±ĝ€¯3.6ĝ€¯%), MSA (0.1ĝ€¯±ĝ€¯0.1ĝ€¯%), glutarate (0.1ĝ€¯±ĝ€¯0.2ĝ€¯%), and maleate (<ĝ€¯0.1ĝ€¯±ĝ€¯0.1ĝ€¯%). Approximately 70ĝ€¯% of TOC remains unaccounted for, highlighting the complex nature of organics in the study region; in samples collected in biomass burning plumes, up to 95.6ĝ€¯% of TOC mass is unaccounted for based on the species detected. Consistent with other regions, monocarboxylic acids dominate the speciated organic mass (g1/4ĝ€¯75ĝ€¯%) and are about 4 times more abundant than dicarboxylic acids. Samples are categorized into four cases based on back-trajectory history, revealing source-independent similarity between the bulk contributions of monocarboxylic and dicarboxylic acids to TOC (16.03ĝ€¯%-23.66ĝ€¯% and 3.70ĝ€¯%-8.75ĝ€¯%, respectively). Furthermore, acetate, formate, succinate, glutarate, pyruvate, oxalate, and MSA are especially enhanced during biomass burning periods, which is attributed to peat emissions transported from Sumatra and Borneo. Lastly, dust (Ca2+) and sea salt (Na+/Cl-) tracers exhibit strong correlations with speciated organics, supporting how coarse aerosol surfaces interact with these water-soluble organics. © Copyright:
    • Total thyroidectomy for giant goiter under local anesthesia and Ketamine in a surgical mission

      Latifi, Rifat; Harper, Joan; Rivera, Renato; Univ Arizona, Dept Surg (ELSEVIER SCI LTD, 2015)
      BACKGROUND: Operation Giving Back (OGB) of the American College of Surgeons (ACS) and various other surgical missions in the developing world have become more popular and provide a valuable way of reducing the surgical burden worldwide. While most cases are "bread and butter" general surgery, difficult surgeries are often encountered. MATERIALS AND METHODS: Description of a total thyroidectomy for super giant goiter extending to chest inferiorly, lateral neck and behind both ears, compressing the trachea and causing chronic difficulties breathing. The surgical team was unable to intubate, but performed surgery under local anesthesia and sedation with Ketamine injection. RESULTS: Total thyroidectomy, as a life-saving procedure, was performed under local anesthesia and Ketamine with mild sedation. Once thyroid was removed, the outside diameter of trachea was assessed to be 4mm. Patient tolerated the procedure well and had no postoperative complication. Her breathing improved significantly post-operatively. Five years later, she is doing well. CONCLUSION: Total thyroidectomy for giant goiters can be done under local anesthesia with Ketamine and proper sedation. Surgeons and anesthesiologists participating in surgical missions may have to perform major surgery under local anesthesia. (C) 2015 The Authors. Published by Elsevier Ltd. on behalf of Surgical Associates Ltd.
    • Touch Probe Tip Compensation Using a Novel Transformation Algorithm for Coordinate Measurements of Curved Surfaces

      Ahn, Hee Kyung; Kang, Hyukmo; Ghim, Young-Sik; Yang, Ho-Soon; Univ Arizona, Coll Opt Sci (SPRINGER/KOREAN SOC PRECISION ENG, 2019-02)
      A transformation algorithm compensating a radius of the probe tip and pre-travel errors is proposed to improve measurement uncertainty of a coordinate measuring machine (CMM). The transformation algorithm does not only compensate a radius of the probe tip, but it also compensates a slipping displacement from the predicted contact point caused by vertical tension for each data point. The performance of the transformation algorithm was successfully demonstrated by applying the transformation algorithm to raw data of an on-axis lens and an off-axis mirror measured with the CMM and comparing them with a reference data measured with UA3P-5 having several tens of nanometer accuracy.
    • Toward a Central Repository for Sharing Nursing Informatics’ Best Practices

      Effken, Judith; Weaver, Charlotte; Cochran, Kelly; Androwich, Ida; O’Brien, Ann; University of Arizona (LIPPINCOTT WILLIAMS & WILKINS, 2016-06)
    • Toward a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition

      Gaubert, B.; Arellano, A. F.; Barré, J.; Worden, H. M.; Emmons, L. K.; Tilmes, S.; Buchholz, R. R.; Vitt, F.; Raeder, K.; Collins, N.; et al. (AMER GEOPHYSICAL UNION, 2016-06-27)
      We examine in detail a 1 year global reanalysis of carbon monoxide (CO) that is based on joint assimilation of conventional meteorological observations and Measurement of Pollution in The Troposphere (MOPITT) multispectral CO retrievals in the Community Earth System Model (CESM). Our focus is to assess the impact to the chemical system when CO distribution is constrained in a coupled full chemistry-climate model like CESM. To do this, we first evaluate the joint reanalysis (MOPITT Reanalysis) against four sets of independent observations and compare its performance against a reanalysis with no MOPITT assimilation (Control Run). We then investigate the CO burden and chemical response with the aid of tagged sectoral CO tracers. We estimate the total tropospheric CO burden in 2002 (from ensemble mean and spread) to be 371 +/- 12% Tg for MOPITT Reanalysis and 291 +/- 9% Tg for Control Run. Our multispecies analysis of this difference suggests that (a) direct emissions of CO and hydrocarbons are too low in the inventory used in this study and (b) chemical oxidation, transport, and deposition processes are not accurately and consistently represented in the model. Increases in CO led to net reduction of OH and subsequent longer lifetime of CH4 (Control Run: 8.7 years versus MOPITT Reanalysis: 9.3 years). Yet at the same time, this increase led to 5-10% enhancement of Northern Hemisphere O-3 and overall photochemical activity via HOx recycling. Such nonlinear effects further complicate the attribution to uncertainties in direct emissions alone. This has implications to chemistry- climate modeling and inversion studies of longer-lived species.
    • TOWARD A NETWORK OF FAINT DA WHITE DWARFS AS HIGH-PRECISION SPECTROPHOTOMETRIC STANDARDS

      Narayan, Gautham; Axelrod, T.; Holberg, J. B.; Matheson, Thomas; Saha, A.; Olszewski, E.; Claver, J.; Stubbs, C. W.; Bohlin, R. C.; Deustua, S.; et al. (IOP PUBLISHING LTD, 2016-05-05)
      We present the initial results from a program aimed at establishing a network of hot DA white dwarfs to serve as spectrophotometric standards for present and future wide-field surveys. These stars span the equatorial zone and are faint enough to be conveniently observed throughout the year with large-aperture telescopes. The spectra of these white dwarfs are analyzed in order to generate a non-local-thermodynamic-equilibrium model atmosphere normalized to Hubble Space Telescope colors, including adjustments for wavelength-dependent interstellar extinction. Once established, this standard star network will serve ground-based observatories in both hemispheres as well as space-based instrumentation from the UV to the near IR. We demonstrate the effectiveness of this concept and show how two different approaches to the problem using somewhat different assumptions produce equivalent results. We discuss the lessons learned and the resulting corrective actions applied to our program.