• C iv Emission-line Properties and Uncertainties in Black Hole Mass Estimates of z ∼ 3.5 Quasars

      Zuo, Wenwen; Wu, Xue-Bing; Fan, Xiaohui; Green, Richard; Yi, Weimin; Schulze, Andreas; Wang, Ran; Bian, Fuyan; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2020-06-11)
      Using a high-luminosity (L-bol similar to 10(47.5)-10(48.3)erg s(-1)), high-redshift (3.2 z < 3.8) quasar sample of 19 quasars with optical and near-infrared spectroscopy, we investigate the reliability of the C iv-based black hole mass estimates (M-BH). The median logarithm of the C iv- and H beta-based M(BH) ratios is 0.110 dex, with a scatter of 0.647 dex. The C iv-to-H beta BH mass differences are significantly correlated with the C iv FWHMs, blueshifts, and asymmetries. Corrections of the C iv FWHM using the blueshift and asymmetry reduce the scatter of the mass differences by similar to 0.04-0.2 dex. Quasars in our sample accrete at the Eddington ratio R(EDD) > 0.3 and cover a considerable range of blueshifts, with 18/19 of the quasars showing C iv blueshifts (with the median value of 1126 km s(-1)) and 14/19 of the quasars showing C iv blueshifts larger than 500 km s(-1). It suggests that not all quasars with high Eddington ratios show large blueshifts. The Baldwin effect between the C iv rest-frame equivalent width (REW) and the continuum luminosity at 1350 A is not seen, likely due to the limited luminosity range of our sample. We find a lack of flux in the red wing of the composite spectrum with larger C iv blueshift and detect a higher ratio of [Oiii] quasars with REW[Oiii] > 5 A in the subsample with lower C iv blueshift. It is more likely that they are caused by the combination of the Eddington ratio and the orientation effect.
    • C-infinity Smoothing for Weak Solutions of the Inhomogeneous Landau Equation

      Henderson, Christopher; Snelson, Stanley; Univ Arizona, Dept Math (SPRINGER, 2019-11-06)
      We consider the spatially inhomogeneous Landau equation with initial data that is bounded by a Gaussian in the velocity variable. In the case of moderately soft potentials, we show that weak solutions immediately become smooth, and remain smooth as long as the mass, energy, and entropy densities remain under control. For very soft potentials, we obtain the same conclusion with the additional assumption that a sufficiently high moment of the solution in the velocity variable remains bounded. Our proof relies on the iteration of local Schauder-type estimates.
    • CA1 pyramidal cells have diverse biophysical properties, affected by development, experience, and aging

      McKiernan, Erin C.; Marrone, Diano F.; Univ Arizona, McKnight Brain Inst; Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México, México; Department of Psychology, Wilfrid Laurier University, Waterloo, Ontario, Canada (PEERJ INC, 2017-09-19)
      Neuron types (e.g., pyramidal cells) within one area of the brain are often considered homogeneous, despite variability in their biophysical properties. Here we review literature demonstrating variability in the electrical activity of CA1 hippocampal pyramidal cells (PCs), including responses to somatic current injection, synaptic stimulation, and spontaneous network-related activity. In addition, we describe how responses of CA1 PCs vary with development, experience, and aging, and some of the underlying ionic currents responsible. Finally, we suggest directions that may be the most impactful in expanding this knowledge, including the use of text and data mining to systematically study cellular heterogeneity in more depth; dynamical systems theory to understand and potentially classify neuron firing patterns; and mathematical modeling to study the interaction between cellular properties and network output. Our goals are to provide a synthesis of the literature for experimentalists studying CA1 PCs, to give theorists an idea of the rich diversity of behaviors models may need to reproduce to accurately represent these cells, and to provide suggestions for future research.
    • Caching rodents disproportionately disperse seed beneath invasive grass

      Sommers, Pacifica; Chesson, Peter; Univ Arizona, Ecol & Evolutionary Biol (WILEY-BLACKWELL, 2017-02-07)
      Seed dispersal by caching rodents is a context-dependent mutualism in many systems. Plants benefit when seed remaining in shallow caches germinates before being eaten, often gaining protection from beetles and a favorable microsite in the process. Caching in highly unfavorable microsites, conversely, could undermine the dispersal benefit for the plant. Plant invasions could disrupt dispersal benefits of seed caching by attracting rodents to the protection of a dense invasive canopy which inhibits the establishment of native seedlings beneath it. To determine whether rodents disproportionately cache seed under the dense canopy of an invasive grass in southeastern Arizona, we used nontoxic fluorescent powder and ultraviolet light to locate caches of seed offered to rodents in the field. We fitted a general habitat-use model, which showed that disproportionate use of plant cover by caching rodents (principally Chaetodipus spp.) increased with moonlight. Across all moon phases, when rodents cached under plants, they cached under the invasive grass disproportionately to its relative cover. A greenhouse experiment showed that proximity to the invasive grass reduced the growth and survival of seedlings of a common native tree (Parkinsonia microphylla) whose seeds are dispersed by caching rodents. Biased dispersal of native seed to the base of an invasive grass could magnify the competitive effect of this grass on native plants, further reducing their recruitment and magnifying the effect of the invasion.
    • Cactus pear: a natural product in cancer chemoprevention

      Zou, Da-ming; Brewer, Molly; Garcia, Francisco; Feugang, Jean; Wang, Jian; Zang, Roungyu; Liu, Huaguang; Zou, Changping; Department of Obstetrics and Gynecology, Arizona Health Sciences Center, University of Arizona, Tucson, Arizona 85724, USA; Division of Gynecologic Oncology, Arizona Cancer Center, Tucson, Arizona 85724, USA; et al. (BioMed Central, 2005)
      BACKGROUND:Cancer chemoprevention is a new approach in cancer prevention, in which chemical agents are used to prevent cancer in normal and/or high-risk populations. Although chemoprevention has shown promise in some epithelial cancers, currently available preventive agents are limited and the agents are costly, generally with side effects. Natural products, such as grape seed, green tea, and certain herbs have demonstrated anti-cancer effects. To find a natural product that can be used in chemoprevention of cancer, we tested Arizona cactus fruit solution, the aqueous extracts of cactus pear, for its anti-cancer effects in cultured cells and in an animal model.METHOD:Aqueous extracts of cactus pear were used to treat immortalized ovarian and cervical epithelial cells, as well as ovarian, cervical, and bladder cancer cells. Aqueous extracts of cactus pear were used at six concentrations (0, 0.5, 1, 5, 10 or 25%) to treat cells for 1, 3, or 5 days. Growth inhibition, apoptosis induction, and cell cycle changes were analyzed in the cultured cells
    • Cadaver Models in Residency Training for Uncommonly Encountered Ultrasound-Guided Procedures

      Amini, Richard; Camacho, Luis D; Valenzuela, Josephine; Ringleberg, Jeannie K; Patanwala, Asad E; Stearns, Jack; Situ-LaCasse, Elaine H; Acuña, Josie; Adhikari, Srikar; Univ Arizona, Dept Emergency Med; et al. (SAGE PUBLICATIONS LTD, 2019-11-19)
      Background: Arthrocentesis of the ankle and elbow and brachial plexus nerve blocks are infrequently performed procedures; however, clinicians in specialties such as emergency medicine are required to be proficient in these procedures in the event of emergent or urgent necessity. Objectives: The objective of this study was to create, implement, and assess a fresh cadaver-based educational model to help resident physicians learn how to perform ultrasound-guided arthrocentesis of the ankle and elbow and ultrasound-guided regional nerve blocks. Methods: This was a single-center cross-sectional study conducted at an academic medical center. After a brief didactic session, 26 emergency medicine residents with varying levels of clinical and ultrasound experience rotated through 4 fresh cadaver-based stations. The objective of each station was to understand the sonographic anatomy and to perform ultrasound-guided arthrocentesis or regional nerve block with hands-on feedback from ultrasound fellows and faculty. Participants were subsequently asked to complete a questionnaire which evaluated participants' experience level, opinions, and procedural confidence regarding the 4 stations. Results: A total of 26 residents participated in this study. All 26 residents agreed that the cadaver model (compared with clinical anatomy) was realistic regarding ultrasound quality of the joint space, ultrasound quality of the joint effusion, ultrasound quality of nerves, tissue density, needle guidance, and artifacts. Finally, there was a statistically significant difference between mean scores for pre-simulation and post-simulation session participant procedural confidence for all 4 procedures. Conclusions: This fresh cadaver-based ultrasound-guided educational model was an engaging and well-received opportunity for residents to gain proficiency and statistically significant confidence in procedures which are uncommonly performed in clinical settings.
    • Cadaver-based abscess model for medical training

      Ellis, Michael; Nelson, Joseph; Kartchner, Jeffrey; Yousef, Karl; Adamas-Rappaport, William; Amini, Richard; Univ Arizona, Coll Med; Univ Arizona, Dept Surg (DOVE MEDICAL PRESS LTD, 2017-01)
      Ultrasound imaging is a rapid and noninvasive tool ideal for the imaging of soft tissue infections and is associated with a change of clinician management plans in 50% of cases. We developed a realistic skin abscess diagnostic and therapeutic training model using fresh frozen cadavers and common, affordable materials. Details for construction of the model and suggested variations are presented. This cadaver-based abscess model produces high-quality sonographic images with internal echogenicity similar to a true clinical abscess, and is ideal for teaching sonographic diagnostic skills in addition to the technical skills of incision and drainage or needle aspiration.
    • Caffeine Enhances Memory Performance in Young Adults during Their Non-optimal Time of Day

      Sherman, Stephanie M.; Buckley, Timothy P.; Baena, Elsa; Ryan, Lee; Univ Arizona, Dept Psychol; Univ Arizona, Evelyn F McKnight Brain Inst (FRONTIERS MEDIA SA, 2016-11-14)
      Many college students struggle to perform well on exams in the early morning. Although students drink caffeinated beverages to feel more awake, it is unclear whether these actually improve performance. After consuming coffee (caffeinated or decaffeinated), college-age adults completed implicit and explicit memory tasks in the early morning and late afternoon (Experiment 1). During the morning, participants ingesting caffeine demonstrated a striking improvement in explicit memory, but not implicit memory. Caffeine did not alter memory performance in the afternoon. In Experiment 2, participants engaged in cardiovascular exercise in order to examine whether increases in physiological arousal similarly improved memory. Despite clear increases in physiological arousal, exercise did not improve memory performance compared to a stretching control condition. These results suggest that caffeine has a specific benefit for memory during students' non-optimal time of day-early morning. These findings have real-world implications for students taking morning exams.
    • Caffeine inhibits PI3K and mTORC2 in Dictyostelium and differentially affects multiple other cAMP chemoattractant signaling effectors

      Tariqul Islam, A F M; Scavello, Margarethakay; Lotfi, Pouya; Daniel, Dustin; Haldeman, Pearce; Charest, Pascale G; Univ Arizona, Dept Chem & Biochem; Univ Arizona, Dept Basic Med Sci (SPRINGER, 2019-07-01)
      Caffeine is commonly used in Dictyostelium to inhibit the synthesis of the chemoattractant cAMP and, therefore, its secretion and the autocrine stimulation of cells, in order to prevent its interference with the study of chemoattractant-induced responses. However, the mechanism through which caffeine inhibits cAMP synthesis in Dictyostelium has not been characterized. Here, we report the effects of caffeine on the cAMP chemoattractant signaling network. We found that caffeine inhibits phosphatidylinositol 3-kinase (PI3K) and mechanistic target of rapamycin complex 2 (mTORC2). Both PI3K and mTORC2 are essential for the chemoattractant-stimulated cAMP production, thereby providing a mechanism for the caffeine-mediated inhibition of cAMP synthesis. Our results also reveal that caffeine treatment of cells leads to an increase in cAMP-induced RasG and Rap1 activation, and inhibition of the PKA, cGMP, MyoII, and ERK1 responses. Finally, we observed that caffeine has opposite effects on F-actin and ERK2 depending on the assay and Dictyostelium strain used, respectively. Altogether, our findings reveal that caffeine considerably affects the cAMP-induced chemotactic signaling pathways in Dictyostelium, most likely acting through multiple targets that include PI3K and mTORC2.
    • Calculating surface ocean pCO(2) from biogeochemical Argo floats equipped with pH: An uncertainty analysis

      Williams, N. L.; Juranek, L. W.; Feely, R. A.; Johnson, K. S.; Sarmiento, J. L.; Talley, L. D.; Dickson, A. G.; Gray, A. R.; Wanninkhof, R.; Russell, Joellen; et al. (AMER GEOPHYSICAL UNION, 2017-03)
      More than 74 biogeochemical profiling floats that measure water column pH, oxygen, nitrate, fluorescence, and backscattering at 10 day intervals have been deployed throughout the Southern Ocean. Calculating the surface ocean partial pressure of carbon dioxide (pCO(2sw)) from float pH has uncertainty contributions from the pH sensor, the alkalinity estimate, and carbonate system equilibrium constants, resulting in a relative standard uncertainty in pCO(2sw) of 2.7% (or 11 mu atm at pCO(2sw) of 400 mu atm). The calculated pCO(2sw) from several floats spanning a range of oceanographic regimes are compared to existing climatologies. In some locations, such as the subantarctic zone, the float data closely match the climatologies, but in the polar Antarctic zone significantly higher pCO(2sw) are calculated in the wintertime implying a greater air-sea CO2 efflux estimate. Our results based on four representative floats suggest that despite their uncertainty relative to direct measurements, the float data can be used to improve estimates for air-sea carbon flux, as well as to increase knowledge of spatial, seasonal, and interannual variability in this flux. Plain Language Summary The Southern Ocean is a key player in the global flow of carbon, yet it is hard to reach, and there are relatively few measurements there, especially in winter. Measuring the amount of carbon dioxide gas in seawater is key to advancing our understanding of the Southern Ocean. More than 74 robotic floats that use sensors to measure seawater properties have been deployed throughout the Southern Ocean, and each has a lifetime of around 5 years. It is currently not possible to directly measure carbon dioxide gas from these floats; however, it is possible to estimate carbon dioxide from things that the float can measure, like pH, a measure of ocean acidity. Here surface ocean carbon dioxide is estimated from several floats and compared to two ship-based estimates. In some locations, the floats closely match the existing estimates, but in other locations the floats see significantly higher surface ocean carbon dioxide in the wintertime, reinforcing the idea that the Southern Ocean's role in the global carbon cycle needs a closer look. Our results show that despite not measuring carbon dioxide directly, these floats will help scientists learn a lot about the Southern Ocean's part in the global flow of carbon.
    • Calendar age of the Baigetobe kurgan from the Iron Age Saka cemetery at Shilikty Valley, Kazakhstan

      Panyushkina, Irina; Slyusarenko, Igor Y; Sala, Renato; Deom, Jean-Marc; Toleubayev, Abdesh T; Laboratory of Tree-Ring Research, University of Arizona (Cambridge Univ Press, 2016)
      his study addresses the development of an absolute chronology for prominent burial sites of Inner Asian nomadic cultures. We investigate Saka archaeological wood from a well-known gold-filled Baigetobe kurgan (burial mound #1 of Shilikty-3 cemetery) to estimate its calendar age using tree-ring and 14C dating. The Saka was the southernmost tribal group of Asian Scythians, who roamed Central Asia during the 1st millennium BC (Iron Age). The Shilikty is a large burial site located in the Altai Mountains along the border between Kazakhstan and China. We present a new floating tree-ring chronology of larch and five new 14C dates from the construction timbers of the Baigetobe kurgan. The results of Bayesian modeling suggest the age of studied timbers is ~730–690 cal BC. This places the kurgan in early Scythian time and authenticates a previously suggested age of the Baigetobe gold collection between the 8th and 7th centuries BC derived from the typology of grave goods and burial rites. Chronolo- gically and stylistically, the Scythian Animal Style gold from the Baigetobe kurgan is closer to Early Scythians in the North Caucasus and Tuva than to the local Saka occurrences in the Kazakh Altai. Our dating results indicate that the Baigetobe kurgan was nearly contemporaneous to the Arjan-2 kurgan (Tuva) and could be one of the earliest kurgans of the Saka-Scythian elite in Central Asia.
    • Calibrating the Planck cluster mass scale with CLASH

      Penna-Lima, M.; Bartlett, J. G.; Rozo, E.; Melin, J.-B.; Merten, J.; Evrard, A. E.; Postman, M.; Rykoff, E.; Univ Arizona, Dept Phys (EDP SCIENCES S A, 2017-08-14)
      We determine the mass scale of Planck galaxy clusters using gravitational lensing mass measurements from the Cluster Lensing And Supernova survey with Hubble (CLASH). We have compared the lensing masses to the Planck Sunyaev-Zeldovich (SZ) mass proxy for 21 clusters in common, employing a Bayesian analysis to simultaneously fit an idealized CLASH selection function and the distribution between the measured observables and true cluster mass. We used a tiered analysis strategy to explicitly demonstrate the importance of priors on weak lensing mass accuracy. In the case of an assumed constant bias, b(SZ), between true cluster mass, M-500, and the Planck mass proxy, M-PL, our analysis constrains 1 - b(SZ) = 0.73 +/- 0.10 when moderate priors on weak lensing accuracy are used, including a zero-mean Gaussian with standard deviation of 8% to account for possible bias in lensing mass estimations. Our analysis explicitly accounts for possible selection bias effects in this calibration sourced by the CLASH selection function. Our constraint on the cluster mass scale is consistent with recent results from the Weighing the Giants program and the Canadian Cluster Comparison Project. It is also consistent, at 1.34 sigma, with the value needed to reconcile the Planck SZ cluster counts with Planck's base Lambda CDM model fit to the primary cosmic microwave background anisotropies.
    • Calibration and use of an ultra-portable field transfer radiometer for automated vicarious calibration

      Wenny, Brian N.; Thome, Kurtis J.; Czapla-Myers, Jeffrey S.; Anderson, Nikolaus J.; Univ Arizona, Coll Opt Sci (SPIE-INT SOC OPTICAL ENGINEERING, 2017)
      A small portable transfer radiometer has been developed as part of an effort to ensure the quality of upwelling radiance at automated test sites used for vicarious calibration in the solar reflective. The test sites, such as the one located at Railroad Valley, are used to predict top-of-atmosphere reflectance relying on ground-based measurements of the atmosphere and surface. The portable transfer radiometer is designed for one-person operation for on-site field calibration the instrumentation used to determine ground-leaving radiance. The current work describes the laboratory-based calibration of the transfer radiometer highlighting the expected accuracy and SI-traceability. Results from recent field deployments of the transfer radiometer are presented to show how the sensor is to be used for 1) evaluating the health of the automated site radiometers, 2) characterizing the surface being measured at the automated test sites, and 3) assessing the error budget for top-of-atmosphere reflectance prediction the test site characterization. Additionally, results from using the transfer radiometer for a radiance-based calibration of the Operational Land Imager are presented.
    • Calibration methods for a dual-wavelength interferometer system

      Ellis, Jonathan D.; Tangari Larrategui, Martin; Brown, Thomas G.; Zhang, Yanqi; Univ Arizona, Coll Opt Sci (SPIE-INT SOC OPTICAL ENGINEERING, 2018)
      Multiple wavelength interferometry has long been considered an option for the measurement of large aspheric slope departures. In particular, a synthetic wavelength offers a variety of approaches by which large phase excursions can be unwrapped. Using multiple wavelengths can create collimation and magnification mismatch errors between the individual wavelengths that arise during beam expansion and propagation. Here, we present and analyze alignment and calibration methods for a dual-wavelength interferometer that can significantly reduce both misalignment errors and chromatic aberrations in the system. To correct for misalignment, a general method is described for the alignment of a dual-wavelength interferometer, including the alignment of lasers, beam expanders, beam splitters for combining beams and for compensating errors in the reference surface, and the fringe imaging system. A Fourier transform test at the detector surface was conducted to validate that there is essentially no magnification difference between two wavelengths resulting from misalignment of optical system. For the chromatic aberration introduced by the optical elements in the system, a ray-trace model of the interferometer has been established, to simulate the chromatic effect that optical elements will have on the measurement results. As an experimental test, we examine an off-axis spherical mirror in a non-null condition using a highly aliased interferogram. The above alignment methods and the results are analyzed based on the simulated system errors. Using this method, we demonstrate a measured surface profile of deviation of lambda/25 which is comparable to a direct measurement profile of the surface on axis using a Fizeau interferometer.
    • Calibration of AGN Reverberation Distance Measurements

      Koshida, Shintaro; Yoshii, Yuzuru; Kobayashi, Yukiyasu; Minezaki, Takeo; Enya, Keigo; Suganuma, Masahiro; Tomita, Hiroyuki; Aoki, Tsutomu; Peterson, Bruce A.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2017-06-14)
      In Yoshii et al., we described a new method for measuring extragalactic distances based on dust reverberation in active galactic nuclei (AGNs), and we validated our new method with Cepheid variable stars. In this Letter, we validate our new method with Type Ia supernovae (SNe Ia) that occurred in two of the AGN host galaxies during our AGN monitoring program: SN 2004bd in NGC 3786 and SN 2008ec in NGC 7469. Their multicolor light curves were observed and analyzed using two widely accepted methods for measuring SN distances, and the distance moduli derived are m= 33.47 +/- 0.15 for SN 2004bd and 33.83 +/- 0.07 for SN 2008ec. These results are used to obtain independently the distance measurement calibration factor, g. The g value obtained from the SN Ia discussed in this Letter is gSN= 10.61 +/- 0.50, which matches, within the range of 1s uncertainty, gDUST = 10.60, previously calculated ab initio in Yoshii et al. Having validated our new method for measuring extragalactic distances, we use our new method to calibrate reverberation distances derived from variations of Ha emission in the AGN broad-line region, extending the Hubble diagram to z approximate to 0.3 where distinguishing between cosmologies is becoming possible.
    • CALIBRATION OF THE VOYAGER ULTRAVIOLET SPECTROMETERS AND THE COMPOSITION OF THE HELIOSPHERE NEUTRALS: REASSESSMENT

      Ben-Jaffel, L.; Holberg, J. B.; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2016-06-02)
      The data harvest from the Voyagers' (V1 and V2) Ultraviolet Spectrometers (UVS) covers encounters with the outer planets, measurements of the heliosphere sky-background, and stellar spectrophotometry. Because their period of operation overlaps with many ultraviolet missions, the calibration of V1. and V2 UVS with other spectrometers is invaluable. Here we revisit the UVS calibration to assess the intriguing sensitivity enhancements of 243% (V1) and 156% (V2) proposed recently. Using the Ly alpha airglow from Saturn, observed in situ by both Voyagers, and remotely by International Ultraviolet Explorer (IUE), we match the Voyager values to IUE, taking into account the shape of the Saturn Ly alpha line observed with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. For all known ranges of the interplanetary hydrogen density, we show that the V1 and V2 UVS sensitivities cannot be enhanced by the amounts thus far proposed. The same diagnostic holds for distinct channels covering the diffuse He I 58.4 nm emission. Our prescription is to keep the original calibration of the Voyager UVS with a maximum uncertainty of 30%, making both instruments some of the most stable EUV/FUV spectrographs in the history of space exploration. In that frame, we reassess the excess Ly alpha emission detected by Voyager UVS deep in the heliosphere, to show its consistency with a heliospheric but not galactic origin. Our finding confirms results obtained nearly two decades ago-namely, the UVS discovery of the distortion of the heliosphere and the corresponding obliquity of the local interstellar magnetic field (similar to 40 degrees from upwind) in the solar system neighborhood-without requiring any revision of the Voyager UVS calibration.
    • Calibration of the island effect: Experimental validation of closed-loop focal plane wavefront control on Subaru/SCExAO

      N’Diaye, M.; Martinache, F.; Jovanovic, N.; Lozi, J.; Guyon, O.; Norris, B.; Ceau, A.; Mary, D.; Univ Arizona, Steward Observ; Univ Arizona, Coll Opt Sci (EDP SCIENCES S A, 2018-02-13)
      Context. Island effect (IE) aberrations are induced by differential pistons, tips, and tilts between neighboring pupil segments on ground-based telescopes, which severely limit the observations of circumstellar environments on the recently deployed exoplanet imagers (e.g., VLT/SPHERE, Gemini/GPI, Subaru/SCExAO) during the best observing conditions. Caused by air temperature gradients at the level of the telescope spiders, these aberrations were recently diagnosed with success on VLT/SPHERE, but so far no complete calibration has been performed to overcome this issue. Aims. We propose closed-loop focal plane wavefront control based on the asymmetric Fourier pupil wavefront sensor (APF-WFS) to calibrate these aberrations and improve the image quality of exoplanet high-contrast instruments in the presence of the IE. Methods. Assuming the archetypal four-quadrant aperture geometry in 8 m class telescopes, we describe these aberrations as a sum of the independent modes of piston, tip, and tilt that are distributed in each quadrant of the telescope pupil. We calibrate these modes with the APF-WFS before introducing our wavefront control for closed-loop operation. We perform numerical simulations and then experimental tests on a real system using Subaru/SCExAO to validate our control loop in the laboratory and on-sky. Results. Closed-loop operation with the APF-WFS enables the compensation for the IE in simulations and in the laboratory for the small aberration regime. Based on a calibration in the near infrared, we observe an improvement of the image quality in the visible range on the SCExAO/VAMPIRES module with a relative increase in the image Strehl ratio of 37%. Conclusions. Our first IE calibration paves the way for maximizing the science operations of the current exoplanet imagers. Such an approach and its results prove also very promising in light of the Extremely Large Telescopes (ELTs) and the presence of similar artifacts with their complex aperture geometry.
    • California's methane super-emitters

      Duren, Riley M; Thorpe, Andrew K; Foster, Kelsey T; Rafiq, Talha; Hopkins, Francesca M; Yadav, Vineet; Bue, Brian D; Thompson, David R; Conley, Stephen; Colombi, Nadia K; et al. (NATURE PUBLISHING GROUP, 2019-11-07)
      Methane is a powerful greenhouse gas and is targeted for emissions mitigation by the US state of California and other jurisdictions worldwide1,2. Unique opportunities for mitigation are presented by point-source emitters-surface features or infrastructure components that are typically less than 10 metres in diameter and emit plumes of highly concentrated methane3. However, data on point-source emissions are sparse and typically lack sufficient spatial and temporal resolution to guide their mitigation and to accurately assess their magnitude4. Here we survey more than 272,000 infrastructure elements in California using an airborne imaging spectrometer that can rapidly map methane plumes5-7. We conduct five campaigns over several months from 2016 to 2018, spanning the oil and gas, manure-management and waste-management sectors, resulting in the detection, geolocation and quantification of emissions from 564 strong methane point sources. Our remote sensing approach enables the rapid and repeated assessment of large areas at high spatial resolution for a poorly characterized population of methane emitters that often appear intermittently and stochastically. We estimate net methane point-source emissions in California to be 0.618 teragrams per year (95 per cent confidence interval 0.523-0.725), equivalent to 34-46 per cent of the state's methane inventory8 for 2016. Methane 'super-emitter' activity occurs in every sector surveyed, with 10 per cent of point sources contributing roughly 60 per cent of point-source emissions-consistent with a study of the US Four Corners region that had a different sectoral mix9. The largest methane emitters in California are a subset of landfills, which exhibit persistent anomalous activity. Methane point-source emissions in California are dominated by landfills (41 per cent), followed by dairies (26 per cent) and the oil and gas sector (26 per cent). Our data have enabled the identification of the 0.2 per cent of California's infrastructure that is responsible for these emissions. Sharing these data with collaborating infrastructure operators has led to the mitigation of anomalous methane-emission activity10.
    • Call and Response: SEM President's Roundtable 2018, “Humanities' Responses to the Anthropocene”

      Cooley, Timothy; Allen, Aaron S.; Hellier, Ruth; Pedelty, Mark; Von Glahn, Denise; Titon, Jeff Todd; Post, Jennifer C.; Univ Arizona, Ethnomusicol (SOC ETHNOMUSICOLOGY INC, 2020-06-01)
    • CALL Beliefs in Context: a Study of US High School Foreign Language Learners

      Hellmich, Emily A.; Univ Arizona, Dept French & Italian (ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2019-07-26)
      Recent calls from applied linguistics and from CALL have emphasized the importance of situating the understanding and use of digital tools for language learning within layered contexts. An important component of these layered contexts is societal discourses of technology, which are multiple and far from neutral. In response to these calls, this study examines how students at one San Francisco Bay Area high school understand technology in foreign language learning and how these beliefs relate to regional discourses of technology. The study assumed an ecological theoretical frame and deployed a multi-pronged research design: a survey study (n = 283), a case study (n = 3), and a discourse analysis of a regional newspaper corpus (n = 372). Findings indicate that students held largely utilitarian beliefs about CALL that both aligned with and diverged from regional discourses. Instances of alignment suggest the potential influence of larger societal discourses on student beliefs about CALL while instances of divergence underscore the need to address the larger role of technology in society when considering CALL beliefs and practices.