• AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at z ≲ 0.5

      Ohyama, Y.; Wada, T.; Matsuhara, H.; Takagi, T.; Malkan, M.; Goto, T.; Egami, E.; Lee, H.-M.; Im, M.; Kim, J.H.; Pearson, C.; Inami, H.; Oyabu, S.; Usui, F.; Burgarella, D.; Mazyed, F.; Imanishi, M.; Jeong, W.-S.; Miyaji, T.; Díaz Tello, J.; Nakagawa, T.; Serjeant, S.; Takeuchi, T. T.; Toba, Y.; White, G. J.; Hanami, H.; Ishigaki, T.; Univ Arizona, Steward Observ (EDP SCIENCES S A, 2018-10-18)
      Context. Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift z less than or similar to 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy. Aims. We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to z similar or equal to 0.5, by paying particular attention to their PAH properties. Methods. We conducted a low-resolution (R similar or equal to 50) slitless spectroscopic survey at 5-13 mu m of 9 mu m flux-selected sources (> 0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 mu m features at z < 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37-18 mu m were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 mu m PAH feature over the 3.5 mu m stellar component of the SEDs. Results. The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 mu m bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at z greater than or similar to 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.
    • "Smooth As Butter": Practices of Music Learning Amongst African-American Children

      Corso, Dawn T. (The University of Illinois (Urbana, Illinois), 2003)
      The purpose of this qualitative study was to describe and analyze the musical content and learning processes apparent among African-American children in Tucson, Arizona, in two settings—an out-of-school summer program and an in-school student-focused musical activity period. Of primary interest were how African-American children demonstrated musical knowledge and skills amongst each other and what the knowledge and skills consisted of. The theoretical issues guiding this study came from research focused on sociocultural perspectives of learning, African-American children’s musical play, and multicultural music education. The conceptual framework for the study is a sociocultural approach based upon Vygotsky’s sociocultural theory (1978, 1986) and modem interpretations of Vygotsky, such as Barbara Rogoffs (1990) notion of apprenticeships and Jean Lave and Etienne Wenger’s (1991) communities of practice. Data was collected primarily through participant observations and formal and informal interviews of the two aforementioned groups in a combined ethnographic and case study design. Field notes, audiotape recordings, videotape recordings, photographs, school enrollment forms, and participant-requested materials were all procedures and devices used in data collection. Jordan and Henderson’s (1995) method of interaction analysis provided the outline for data analyses, while the specific protocol of Emerson, Fretz, and Shaw (1995) was implemented for field note and audiotape analyses and Collier and Collier’s (1986) method of photograph and videotape analyses was followed. The results of this study lead to several arguments. First, children learn music by participating to varying degrees within a community of practice. Individuals within the group serve as sources of information and skill based upon their own expertise and interest creating an environment of reciprocity and shifting leadership. Furthermore, the bonds of friendship strengthen these communities of practice by providing pre-established common ground, intimacy, and concern amongst members. Second, musical play simultaneously functions to prepare children for adult life and allows children to engage in recreational entertainment. Moreover, the activities serve the distinct purposes of identity and gender-role formation and allow for exploration in areas of power and sexuality, especially as they apply to females. Finally, although specific musical abilities may not be chronologically developmental, engaging in particular musical activities is. Handclaps were most common among children ages seven to nine years, drills were practiced mainly between the ages of nine to 11 years, and dances were most frequent amongst children ages 11 to 12 years. A possible reason for the age-graded activities might be the increasing awareness and use of social commentary present in the lyrics and movements of a music activity genre, rather than the technical complexity across a musical activity genre or genres. The implications of these findings are for music educators who would like to improve their understanding of African-American musical traditions and revise their teaching methods to be sensitive to this cultural group; creators of music curricula and standards choosing to reform existing ideology and materials to be more multiculturally comprehensive; ethnomusicologists concerned with expanding information regarding the musical culture of African-American children; and educational psychologists interested in expanding the area of sociocultural learning theory, especially regarding ideas of learning through practice, contexts of activity, and developmental sequencing of knowledge and skills.
    • An Examination of the Ideas and Practices Regarding Multicultural Education of Elementary General Music Teachers in Champaign County, Illinois

      Corso, Dawn T. (The University of Illinois (Urbana, Illinois), 1999)
      This study concerns the ideas and practices of general music teachers regarding multiculturalism in elementary music education, specifically, general music educators in the public schools of Champaign County, Illinois. Data was collected by mailed, open-ended questionnaires completed by the general music teachers from 11 of the existing 37 schools. Responses were analyzed by frequency and according to a theoretical framework of multicultural education rendered by James Banks (1997). Major findings included that teachers were very positive about the concept of multicultural education, but that they failed to recognize multicultural education to its fullest extent conceptually or in or practice. Teachers thought of and practiced multicultural education mainly in terms of content integration and somewhat in terms of reducing prejudices and providing an empowering school and social structure, neglected the aspect of an equitable pedagogy, and failed to realize the import of reflecting on the knowledge construction process in music education. This incomplete realization may be due to the practical constraints of teaching, such as administrative concerns or lack of resources, or a school setting that is seemingly culturally homogenous, but is most probably due to music educators' failure to realize the necessity for understanding musics as cultural phenomena and not as a universal constant. Overall, findings indicated that teachers lacked the necessary preparation in terms of pre-service and in-service training and education to approach multicultural education in a comprehensive manner.
    • A labor day warning

      Robbins, Richard A.; The University of Arizona College of Medicine - Phoenix (Arizona Thoracic Society, 2018-09-03)
    • Antibiotics as Anti-inflammatories in Pulmonary Diseases

      Robbins, Richard; The University of Arizona College of Medicine - Phoenix (Arizona Thoracic Society, 2018-09-21)
      The currently available evidence for the use of chronic antibiotic therapy, principally macrolides and tetracyclines, as anti-inflammatory therapy in pulmonary disorders is reviewed. Historically, treatment of a number of chronic diseases with tetracyclines showed modest benefits but reports of the successful treatment of diffuse panbronchiolitis with erythromycin stimulated research in other lung diseases as well as shifting the focus from tetracyclines to macrolides. Chronic macrolide therapy is now recommended for patients with frequent exacerbations of cystic fibrosis and COPD and considerable evidence exists for potential benefits in asthma. There is also evidence of macrolide efficacy in the prevention of obliterative bronchiolitis after lung transplantation. Small trials have suggested possible benefit of macrolides in IPF. Taken together these suggest a potential for antibiotics, particularly macrolides, in some pulmonary inflammatory disorders.
    • The Near-infrared Transmission Spectra of TRAPPIST-1 Planets b, c, d, e, f, and g and Stellar Contamination in Multi-epoch Transit Spectra

      Zhang, Zhanbo; Zhou, Yifan; Rackham, Benjamin V.; Apai, Dániel; Univ Arizona, Dept Astron, Steward Observ (IOP PUBLISHING LTD, 2018-10)
      The seven approximately Earth-sized transiting planets in the TRAPPIST-1 system provide a unique opportunity to explore habitable-and nonhabitable-zone small planets within the same system. Its habitable-zone exoplanets-due to their favorable transit depths-are also worlds for which atmospheric transmission spectroscopy is within reach with the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST). We present here an independent reduction and analysis of two HST Wide Field Camera 3 (WFC3) near-infrared transit spectroscopy data sets for six planets (b through g). Utilizing our physically motivated detector charge-trap correction and a custom cosmic-ray correction routine, we confirm the general shape of the transmission spectra presented by de Wit et al. Our data reduction approach leads to a 25% increase in the usable data and reduces the risk of confusing astrophysical brightness variations (e.g., flares) with instrumental systematics. No prominent absorption features are detected in any individual planet's transmission spectra; by contrast, the combined spectrum of the planets shows a suggestive decrease around 1.4 mu m similar to an inverted water absorption feature. Including transit depths from K2, the SPECULOOS-South Observatory, and Spitzer, we find that the complete transmission spectrum is fully consistent with stellar contamination owing to the transit light source effect. These spectra demonstrate how stellar contamination can overwhelm planetary absorption features in low-resolution exoplanet transit spectra obtained by HST and JWST and also highlight the challenges in combining multi-epoch observations for planets around rapidly rotating spotted stars.
    • Dynamical Constraints on the HR 8799 Planets with GPI

      Wang, Jason J.; Graham, James R.; Dawson, Rebekah; Fabrycky, Daniel; De Rosa, Robert J.; Pueyo, Laurent; Konopacky, Quinn; Macintosh, Bruce; Marois, Christian; Chiang, Eugene; Ammons, S. Mark; Arriaga, Pauline; Bailey, Vanessa P.; Barman, Travis; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Esposito, Thomas M.; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Nielsen, Eric L.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Ruffio, Jean-Baptiste; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2018-11)
      The HR 8799 system uniquely harbors four young super-Jupiters whose orbits can provide insights into the system's dynamical history and constrain the masses of the planets themselves. Using the Gemini Planet Imager, we obtained down to one milliarcsecond precision on the astrometry of these planets. We assessed four-planet orbit models with different levels of constraints and found that assuming the planets are near 1:2:4:8 period commensurabilities, or are coplanar, does not worsen the fit. We added the prior that the planets must have been stable for the age of the system (40 Myr) by running orbit configurations from our posteriors through N-body simulations and varying the masses of the planets. We found that only assuming the planets are both coplanar and near 1:2:4:8 period commensurabilities produces dynamically stable orbits in large quantities. Our posterior of stable coplanar orbits tightly constrains the planets' orbits, and we discuss implications for the outermost planet b shaping the debris disk. A four-planet resonance lock is not necessary for stability up to now. However, planet pairs d and e, and c and d, are each likely locked in two-body resonances for stability if their component masses are above 6 M-Jup and 7 M-Jup, respectively. Combining the dynamical and luminosity constraints on the masses using hot-start evolutionary models and a system age of 42 +/- 5 Myr, we found the mass of planet b to be 5.8 +/- 0.5 M-Jup, and the masses of planets c, d, and e to be 7.2(-0.7)(+0.6) M-Jup each.
    • The Gemini/Hubble Space Telescope Galaxy Cluster Project: Stellar Populations in the Low-redshift Reference Cluster Galaxies

      Jørgensen, Inger; Chiboucas, Kristin; Webb, Kristi; Woodrum, Charity; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11)
      In order to study stellar populations and galaxy structures at intermediate and high redshift (z = 0.2-2.0) and link these properties to those of low-redshift galaxies, there is a need for well-defined local reference samples. Especially for galaxies in massive clusters, such samples are often limited to the Coma cluster galaxies. We present consistently calibrated velocity dispersions and absorption-line indices for galaxies in the central 2 R-500 x 2 R-500 of four massive clusters at z < 0.1: Abell 426/Perseus, Abell 1656/Coma, Abell 2029, and Abell 2142. The measurements are based on data from the Gemini Observatory, McDonald Observatory, and Sloan Digital Sky Survey. For bulge-dominated galaxies, the samples are 95% complete in Perseus and Coma and 74% complete in A2029 and A2142, to a limit of M-B,M-abs <= -18.5 mag. The data serve as the local reference for our studies of galaxy populations in the higher-redshift clusters that are part of the Gemini/HST Galaxy Cluster Project (GCP). We establish the scaling relations between line indices and velocity dispersions as a reference for the GCP. We derive stellar population parameters, ages, metallicities [M/H], and abundance ratios from line indices, both averaged in bins of velocity dispersion and from individual measurements for galaxies in Perseus and Coma. The zero points of relations between the stellar population parameters and the velocity dispersions limit the allowed cluster-to-cluster variation of the four clusters to +/- 0.08 dex in age, +/- 0.06 dex in [M/H], +/- 0.07 dex in [CN/Fe], and +/- 0.03 dex in [Mg/Fe].
    • Nonlocal Damage Mechanics for Quantification of Health for Piezoelectric Sensor

      Habib, A.; Shelke, A.; Amjad, U.; Pietsch, U.; Banerjee, S.; Univ Arizona, Dept Civil Engn (MDPI, 2018-09)
      In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is presented. An intrinsic length scale parameter obtained from nonlocal field theory is used as a novel measure for quantification of damage precursor. Features such as amplitude decay, attenuation, frequency shifts and higher harmonics of guided waves are commonly-used damage features. Quantification of the precursors to damage by considering the mentioned features in a single framework is a difficult proposition. Therefore, a nonlocal field theory is formulated and a nonlocal damage index is proposed. The underlying idea of the paper is that inception of the damage at the micro scale manifests the evolution of damage at the macro scale. In this paper, we proposed a nonlocal field theory, which can efficiently quantify the inception of damage on piezoelectric crystals. The strength of the method is demonstrated by employing the surface acoustic waves (SAWs) and longitudinal bulk waves in Lithium Niobate (LiNbO3) single crystal. A control damage was introduced and its manifestation was expressed using the intrinsic dominant length scale. The SAWs were excited and detected using interdigital transducers (IDT) for healthy and damage state. The acoustic imaging of microscale damage in piezoelectric crystal was conducted using scanning acoustic microscopy (SAM). The intrinsic damage state was then quantified by overlaying changes in time of flight (TOF) and frequency shift on the angular dispersion relationship.
    • Interfacial energy band and phonon scattering effect in Bi2Te3-polypyrrole hybrid thermoelectric material

      Kim, Cham; Baek, Ju Young; Lopez, David Humberto; Kim, Dong Hwan; Kim, Hoyoung; Univ Arizona, Dept Chem & Environm Engn (AMER INST PHYSICS, 2018-10-08)
      We hybridized n-type Bi2Te3 with an inexpensive and abundantly available conducting polymer, polypyrrole, to obtain a bulk-structured hybrid material in which the interfacial energy band and the phonon scattering effects should occur at the interface of the two components. The obtained hybrid material inevitably exhibited a lower electrical conductivity than pristine Bi2Te3, which may be attributable to carrier scattering at the interfacial energy barrier. However, the hybrid material completely compensated for this loss in electrical conductivity with a significant increase in the Seebeck coefficient, and thus it retained the power factor with no loss. In addition, the hybrid material displayed a much lower thermal conductivity than pristine Bi2Te3 owing to the phonon scattering effect. The hybrid material exhibited significant decoupling of the electrical and thermal properties, thus affording state-of-the-art figures of merit (ZT similar to 0.98 at 25 degrees C, ZT(max) similar to 1.21 at 100 degrees C, and ZT(ave) similar to 1.18 at 50-150 degrees C) that exceed those of most of the previously reported n-type Bi2Te3 or Bi-2(Te,Se)(3) materials. Published by AIP Publishing.
    • Atypical Flowers Can Be as Profitable as Typical Hummingbird Flowers

      Waser, Nickolas M.; CaraDonna, Paul J.; Price, Mary V.; Univ Arizona, Sch Nat Resources & Environm (UNIV CHICAGO PRESS, 2018-11)
      In western North America, hummingbirds can be observed systematically visiting flowers that lack the typical reddish color, tubular morphology, and dilute nectar of hummingbird flowers. Curious about this behavior, we asked whether these atypical flowers are energetically profitable for hummingbirds. Our field measurements of nectar content and hummingbird foraging speeds, taken over four decades at multiple localities, show that atypical flowers can be as profitable as typical ones and suggest that the profit can support 24-h metabolic requirements of the birds. Thus, atypical flowers may contribute to successful migration of hummingbirds, enhance their population densities, and allow them to occupy areas seemingly depauperate in suitable resources. These results illustrate what can be gained by attending to the unexpected.
    • Fumarate hydratase inactivation in hereditary leiomyomatosis and renal cell cancer is synthetic lethal with ferroptosis induction

      Kerins, Michael J.; Milligan, John; Wohlschlegel, James A.; Ooi, Aikseng; Univ Arizona, Coll Pharm, Dept Pharmacol & Toxicol (WILEY, 2018-09)
      Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a hereditary cancer syndrome characterized by inactivation of the Krebs cycle enzyme fumarate hydratase (FH). HLRCC patients are at high risk of developing kidney cancer of type 2 papillary morphology that is refractory to current radiotherapy, immunotherapy and chemotherapy. Hence, an effective therapy for this deadly form of cancer is urgently needed. Here, we show that FH inactivation (FH-/-) proves synthetic lethal with inducers of ferroptosis, an iron-dependent and nonapoptotic form of cell death. Specifically, we identified gene signatures for compound sensitivities based on drug responses for 9 different drug classes against the NCI-60 cell lines. These signatures predicted that ferroptosis inducers would be selectively toxic to FH-/- cell line UOK262. Preferential cell death against UOK262-FH-/- was confirmed with 4 different ferroptosis inducers. Mechanistically, the FH-/- sensitivity to ferroptosis is attributed to dysfunctional GPX4, the primary cellular defender against ferroptosis. We identified that C93 of GPX4 is readily post-translationally modified by fumarates that accumulate in conditions of FH-/-, and that C93 modification represses GPX4 activity. Induction of ferroptosis in FH-inactivated tumors represents an opportunity for synthetic lethality in cancer.
    • Opportunities and Challenges for Dietary Arsenic Intervention

      Nachman, Keeve E.; Punshon, Tracy; Rardin, Laurie; Signes-Pastor, Antonio J.; Murray, Carolyn J.; Jackson, Brian P.; Guerinot, Mary Lou; Burke, Thomas A.; Chen, Celia Y.; Ahsan, Habibul; Argos, Maria; Cottingham, Kathryn L.; Cubadda, Francesco; Ginsberg, Gary L.; Goodale, Britton C.; Kurzius-Spencer, Margaret; Meharg, Andrew A.; Miller, Mark D.; Nigra, Anne E.; Pendergrast, Claire B.; Raab, Andrea; Reimer, Ken; Scheckel, Kirk G.; Schwerdtle, Tanja; Taylor, Vivien F.; Tokar, Erik J.; Warczak, Todd M.; Karagas, Margaret R.; Univ Arizona, Coll Med, Dept Pediat; Univ Arizona, Mel & Enid Coll Publ Hlth, Dept Community Environm & Policy (US DEPT HEALTH HUMAN SCIENCES PUBLIC HEALTH SCIENCE, 2018-08)
      The diet is emerging as the dominant source of arsenic exposure for most of the U.S. population. Despite this, limited regulatory efforts have been aimed at mitigating exposure, and the role of diet in arsenic exposure and disease processes remains understudied. In this brief, we discuss the evidence linking dietary arsenic intake to human disease and discuss challenges associated with exposure characterization and efforts to quantify risks. In light of these challenges, and in recognition of the potential longer-term process of establishing regulation, we introduce a framework for shorter-term interventions that employs a field-to-plate food supply chain model to identify monitoring, intervention, and communication opportunities as part of a multisector, multiagency, science-informed, public health systems approach to mitigation of dietary arsenic exposure. Such an approach is dependent on coordination across commodity producers, the food industry, nongovernmental organizations, health professionals, researchers, and the regulatory community.
    • Neck Dissection Technique Commonality and Variance: A Survey on Neck Dissection Technique Preferences among Head and Neck Oncologic Surgeons in the American Head and Neck Society

      Hemmat, Shirin; Wang, Steven; Ryan, William; Univ Arizona, Dept Otolaryngol Head & Neck Surg (GEORG THIEME VERLAG KG, 2017-01)
      Introduction Neck dissection (ND) technique preferences are not well reported. Objective The objective of this study is to educate practitioners and trainees about surgical technique commonality and variance used by head and neck oncologic surgeons when performing a ND. Methods Online survey of surgeon members of the American Head and Neck Society (AHNS). Survey investigated respondents' demographic information, degree of surgical experience, ND technique preferences. Results In our study, 283 out of 1,010 (28%) AHNS surgeon members with a mean age of 50.3 years (range 32-77 years) completed surveys from 41 states and 24 countries. We found that 205 (72.4%) had completed a fellowship in head and neck surgical oncology. Also, 225 (79.5%) respondents reported completing more than 25 NDs per year. ND technique commonalities (>66% respondents) included: preserving level 5 (unless with suspicious lymph nodes (LN)), only excising the portion of sternocleidomastoid muscle involved with tumor, resecting lymphatic tissue en bloc, preservation of cervical sensory rootlets, not performing submandibular gland (SMG) transfer, placing one drain for unilateral selective NDs, and performing a ND after parotidectomy and thyroidectomy and before transcervical approaches to upper aerodigestive tract primary site. Variability existed in the sequence of LN levels excised, instrument preferences, criteria for drain removal, the timing of a ND with transoral upper aerodigestive tract primary site resections, and submandibular gland preservation. Results showed that 122 (43.1%) surgeons reported that they preserve the submandibular gland during the level 1b portion of a ND. Conclusions The commonalities and variances reported for the ND technique may help put individual preferences into context.
    • Colorless green ideas do sleep furiously: gradient acceptability and the nature of the grammar

      Sprouse, Jon; Yankama, Beracah; Indurkhya, Sagar; Fong, Sandiway; Berwick, Robert C.; Univ Arizona (DE GRUYTER MOUTON, 2018-09)
      In their recent paper, Lau, Clark, and Lappin explore the idea that the probability of the occurrence of word strings can form the basis of an adequate theory of grammar (Lau, Jey H., Alexander Clark & 15 Shalom Lappin. 2017. Grammaticality, acceptability, and probability: A prob-abilistic view of linguistic knowledge. Cognitive Science 41(5): 1201-1241). To make their case, they present the results of correlating the output of several probabilistic models trained solely on naturally occurring sentences with the gradient acceptability judgments that humans report for ungrammatical sentences derived from roundtrip machine translation errors. In this paper, we first explore the logic of the Lau et al. argument, both in terms of the choice of evaluation metric (gradient acceptability), and in the choice of test data set (machine translation errors on random sentences from a corpus). We then present our own series of studies intended to allow for a better comparison between LCL's models and existing grammatical theories. We evaluate two of LCL's probabilistic models (trigrams and recurrent neural network) against three data sets (taken from journal articles, a textbook, and Chomsky's famous colorless-green-ideas sentence), using three evaluation metrics (LCL's gradience metric, a categorical version of the metric, and the experimental-logic metric used in the syntax literature). Our results suggest there are very real, measurable cost-benefit tradeoffs inherent in LCL's models across the three evaluation metrics. The gain in explanation of gradience (between 13% and 31% of gradience) is offset by losses in the other two metrics: a 43%-49% loss in coverage based on a categorical metric of explaining acceptability, and a loss of 12%-35% in explaining experimentally-defined phenomena. This suggests that anyone wishing to pursue LCL's models as competitors with existing syntactic theories must either be satisfied with this tradeoff, or modify the models to capture the phenomena that are not currently captured.

      Earl, Jennifer; Univ Arizona, Sociol; Univ Arizona, Govt & Publ Policy (COORDINAMENTO SIBA, 2018)
    • Sentinel-2A MSI and Landsat-8 OLI radiometric cross comparison over desert sites

      Barsi, Julia A.; Alhammoud, Bahjat; Czapla-Myers, Jeffrey; Gascon, Ferran; Haque, Md. Obaidul; Kaewmanee, Morakot; Leigh, Larry; Markham, Brian L.; Univ Arizona, Coll Opt Sci (ASSOC ITALIANA TELERILEVAMENTO, 2018)
      The Sentinel-2A and Landsat-8 satellites carry on-board moderate resolution multispectral imagers for the purpose of documenting the Earth's changing surface. Though they are independently built and managed, users will certainly take advantage of the opportunity to have higher temporal coverage by combining the datasets. Thus it is important for the radiometric and geometric calibration of the MultiSpectral Instrument (MSI) and the Operational Land Imager (OLI) to be compatible. Cross-calibration of MSI to OLI has been accomplished using multiple techniques involving the use of pseu do-invariant calibration sites (PICS) using direct comparisons as well as through use of PICS models predicting top-of-atmosphere reflectance. A team from the University of Arizona is acquiring field data under both instruments for vicarious calibration of the sensors. This paper shows that the work done to date by the Landsat and Sentinel-2 calibration teams has resulted in stable radiometric calibration for each instrument and consistency to similar to 2.5% between the instruments for all the spectral bands that the instruments have in common.
    • Widespread CCH and c-C3H2 in the Helix Nebula: Unraveling the Chemical History of Hydrocarbons

      Schmidt, D. R.; Zack, L. N.; Ziurys, L. M.; Univ Arizona, Steward Observ; Univ Arizona, Dept Chem & Biochem (IOP PUBLISHING LTD, 2018-09-10)
      The hydrocarbons CCH and c-C3H2 have been detected at multiple positions distributed across the Helix, along with the CN, indicating that these molecules are present throughout this very old planetary nebula. The species were identified by observations of the N = 1 -> 0 transitions of CCH and CN and the J = 2(1,2) -> 10,1 transition of c-C3H2, conducted with the new Atacama Large Millimeter/submillimeter Array (ALMA) prototype 12 m antenna of the Arizona Radio Observatory at 3 mm in wavelength. Column densities of the three species were calculated to be N-tot(CCH) similar to (0.8-6.6) x 10(12) cm(-2), N-tot(c-C3H2) similar to (0.3-5.9). x 10(11) cm(-2), and Ntot(CN) similar to (0.7-7.4). x. 10(12) cm(-2), corresponding to fractional abundances, with respect to H-2, of f(CCH) similar to (1.1-8.8). x. 10(-7), f (c-C3H2) similar to (0.4-7.9) x 10(-8), and f(CN) similar to (0.9-9.9) x 10(-7). Surprisingly, the abundances are comparable to those measured in younger planetary nebulae (PNe), indicating that predicted photodestruction processes for gas-phase molecules are inefficient in these objects, even over long timescales. The distributions of these two hydrocarbons in the Helix appear to be correlated, with a ratio of [CCH]/[c-C3H2] similar to 5-80 and an average value of 29 +/- 6-remarkably similar to both the range ([CCH]/[c-C3H2] similar to 11-53) and average value (28.2 +/- 1.4) found in diffuse clouds. The abundances of CCH, c-C3H2, and CN in the Helix are also factors of 10-100 greater than those measured in diffuse gas. These results suggest that molecular ejecta from PNe are a possible external source for polyatomic species found in diffuse clouds, including C-60.
    • Using GRACE to Estitmate Snowfall Accumulation and Assess Gauge Undercatch Corrections in High Latitudes

      Behrangi, Ali; Gardner, Alex; Reager, John T.; Fisher, Joshua B.; Yang, Daqing; Huffman, George J.; Adler, Robert F.; Univ Arizona, Dept Hydrol & Atmospher Sci (AMER METEOROLOGICAL SOC, 2018-11)
      Ten years of terrestrial water storage anomalies from the Gravity Recovery and Climate Experiment (GRACE) were used to estimate high-latitude snowfall accumulation using a mass balance approach. The estimates were used to assess two common gauge-undercatch correction factors (CFs): the Legates climatology (CF-L) utilized in the Global Precipitation Climatology Project (GPCP) and the Fuchs dynamic correction model (CF-F) used in the Global Precipitation Climatology Centre (GPCC) monitoring product. The two CFs can be different by more than 50%. CF-L tended to exceed CF-F over northern Asia and Eurasia, while the opposite was observed over North America. Estimates of snowfall from GPCP, GPCC-L (GPCC corrected by CF-L), and GPCC-F (GPCC corrected by CF-F) were 62%, 64%, and 46% more than GPCC over northern Asia and Eurasia. The GRACE-based estimate (49% more than GPCC) was the closest to GPCC-F. We found that as near-surface air temperature decreased, the products increasingly underestimated the GRACE-based snowfall accumulation. Overall, GRACE showed that CFs are effective in improving GPCC estimates. Furthermore, our case studies and overall statistics suggest that CF-F is likely more effective than CF-L in most of the high-latitude regions studied here. GPCP showed generally better skill than GPCC-L, which might be related to the use of satellite data or additional quality controls on gauge inputs to GPCP. This study suggests that GPCP can be improved if it employs CF-L instead of CF-F to correct for gauge undercatch. However, this implementation requires further studies, region-specific analysis, and operational considerations.
    • Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-degenerate Double-detonation Type Ia Supernovae

      Shen, Ken J.; Boubert, Douglas; Gänsicke, Boris T.; Jha, Saurabh W.; Andrews, Jennifer E.; Chomiuk, Laura; Foley, Ryan J.; Fraser, Morgan; Gromadzki, Mariusz; Guillochon, James; Kotze, Marissa M.; Maguire, Kate; Siebert, Matthew R.; Smith, Nathan; Strader, Jay; Badenes, Carles; Kerzendorf, Wolfgang E.; Koester, Detlev; Kromer, Markus; Miles, Broxton; Pakmor, Rüdiger; Schwab, Josiah; Toloza, Odette; Toonen, Silvia; Townsley, Dean M.; Williams, Brian J.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-09-20)
      Double detonations in double white dwarf (WD) binaries undergoing unstable mass transfer have emerged in recent years as one of the most promising Type Ia supernova (SN Ia) progenitor scenarios. One potential outcome of this "dynamically driven double-degenerate double-detonation" (D-6) scenario is that the companion WD survives the explosion and is flung away with a velocity equal to its >1000 km s(-1) pre-SN orbital velocity. We perform a search for these hypervelocity runaway WDs using Gaia's second data release. In this paper, we discuss seven candidates followed up with ground-based instruments. Three sources are likely to be some of the fastest known stars in the Milky Way, with total Galactocentric velocities between 1000 and 3000 km s(-1), and are consistent with having previously been companion WDs in pre-SN. Ia systems. However, although the radial velocity of one of the stars is >1000 km s(-1), the radial velocities of the other two stars are puzzlingly consistent with 0. The combined five-parameter astrometric solutions from Gaia and radial velocities from follow-up spectra yield tentative 6D confirmation of the D-6 scenario. The past position of one of these stars places it within a faint, old SN remnant, further strengthening the interpretation of these candidates as hypervelocity runaways from binary systems that underwent SNe Ia.