This open access archive contains publications from University of Arizona faculty, researchers and staff, primarily open-access versions of formally published journal articles. The collection includes published articles and final accepted manuscripts submitted by UA faculty under the UA Open Access Policy. The collection also includes books, book chapters, book reviews, presentations, data, and other scholarly materials submitters have chosen to make available in the repository.

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Recent Submissions

  • Superparamagnetic perpendicular magnetic tunnel junctions for true random number generators

    Parks, Bradley; Bapna, Mukund; Igbokwe, Julianne; Almasi, Hamid; Wang, Weigang; Majetich, Sara A.; Univ Arizona, Dept Phys & Astron (AMER INST PHYSICS, 2018-05)
    Superparamagnetic perpendicular magnetic tunnel junctions are fabricated and analyzed for use in random number generators. Time-resolved resistance measurements are used as streams of bits in statistical tests for randomness. Voltage control of the thermal stability enables tuning the average speed of random bit generation up to 70 kHz in a 60 nm diameter device. In its most efficient operating mode, the device generates random bits at an energy cost of 600 fJ/bit. A narrow range of magnetic field tunes the probability of a given state from 0 to 1, offering a means of probabilistic computing. (C) 2017 Author(s).
  • Summary results of the 2014-2015 DARPA Chikungunya challenge

    Del Valle, Sara Y.; McMahon, Benjamin H.; Asher, Jason; Hatchett, Richard; Lega, Joceline C.; Brown, Heidi E.; Leany, Mark E.; Pantazis, Yannis; Roberts, David J.; Moore, Sean; Peterson, A Townsend; Escobar, Luis E.; Qiao, Huijie; Hengartner, Nicholas W.; Mukundan, Harshini; Univ Arizona, Epidemiol & Biostat Dept (BIOMED CENTRAL LTD, 2018-05-30)
    Background: Emerging pathogens such as Zika, chikungunya, Ebola, and dengue viruses are serious threats to national and global health security. Accurate forecasts of emerging epidemics and their severity are critical to minimizing subsequent mortality, morbidity, and economic loss. The recent introduction of chikungunya and Zika virus to the Americas underscores the need for better methods for disease surveillance and forecasting. Methods: To explore the suitability of current approaches to forecasting emerging diseases, the Defense Advanced Research Projects Agency (DARPA) launched the 2014-2015 DARPA Chikungunya Challenge to forecast the number of cases and spread of chikungunya disease in the Americas. Challenge participants (n = 38 during final evaluation) provided predictions of chikungunya epidemics across the Americas for a six-month period, from September 1, 2014 to February 16, 2015, to be evaluated by comparison with incidence data reported to the Pan American Health Organization (PAHO). This manuscript presents an overview of the challenge and a summary of the approaches used by the winners. Results: Participant submissions were evaluated by a team of non-competing government subject matter experts based on numerical accuracy and methodology. Although this manuscript does not include in-depth analyses of the results, cursory analyses suggest that simpler models appear to outperform more complex approaches that included, for example, demographic information and transportation dynamics, due to the reporting biases, which can be implicitly captured in statistical models. Mosquito-dynamics, population specific information, and dengue-specific information correlated best with prediction accuracy. Conclusion: We conclude that with careful consideration and understanding of the relative advantages and disadvantages of particular methods, implementation of an effective prediction system is feasible. However, there is a need to improve the quality of the data in order to more accurately predict the course of epidemics.
  • Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra

    Souto, Diogo; Unterborn, Cayman T.; Smith, Verne V.; Cunha, Katia; Teske, Johanna; Covey, Kevin; Rojas-Ayala, Bárbara; García-Hernández, D. A.; Stassun, Keivan; Zamora, Olga; Masseron, Thomas; Johnson, J. A.; Majewski, Steven R.; Jönsson, Henrik; Gilhool, Steven; Blake, Cullen; Santana, Felipe; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-06-10)
    The first detailed chemical abundance analysis of the M-dwarf (M4.0) exoplanet-hosting star Ross 128 is presented here, based upon near-infrared (1.5-1.7 mu m), high-resolution (R similar to 22,500) spectra from the SDSS Apache Point Galactic Evolution Experiment survey. We determined precise atmospheric parameters T-eff = 3231 +/- 100 K, log g = 4.96 +/- 0.11 dex and chemical abundances of eight elements (C, O, Mg, Al, K, Ca, Ti, and Fe), finding Ross 128 to have near solar metallicity ([Fe/H] = +0.03 +/- 0.09 dex). The derived results were obtained via spectral synthesis (1D LTE) adopting both MARCS and PHOENIX model atmospheres; stellar parameters and chemical abundances derived from the different adopted models do not show significant offsets. Mass-radius modeling of Ross 128b indicates that it lies below the pure-rock composition curve, suggesting that it contains a mixture of rock and iron, with the relative amounts of each set by the ratio of Fe/Mg. If Ross 128b formed with a subsolar Si abundance, and assuming the planet's composition matches that of the host star, it likely has a larger core size relative to the Earth despite this producing a planet with a Si/Mg abundance ratio similar to 34% greater than the Sun. The derived planetary parameters-insolation flux (S-Earth = 1.79 +/- 0.26) and equilibrium temperature (T-eq = 294. +/-. 10 K)-support previous findings that Ross 128b is a temperate exoplanet in the inner edge of the habitable zone.
  • Space-based Coronagraphic Imaging Polarimetry of the TW Hydrae Disk: Shedding New Light on Self-shadowing Effects

    Poteet, Charles A.; Chen, Christine H.; Hines, Dean C.; Perrin, Marshall D.; Debes, John H.; Pueyo, Laurent; Schneider, Glenn; Mazoyer, Johan; Kolokolova, Ludmilla; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-06-20)
    We present Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer coronagraphic imaging polarimetry of the TW Hydrae protoplanetary disk. These observations simultaneously measure the total and polarized intensity, allowing direct measurement of the polarization fraction across the disk. In accord with the self-shadowing hypothesis recently proposed by Debes et al., we find that the total and polarized intensity of the disk exhibits strong azimuthal asymmetries at projected distances consistent with the previously reported bright and dark ring-shaped structures (similar to 45-99 au). The sinusoidal-like variations possess a maximum brightness at position angles near similar to 268 degrees-300 degrees and are up to similar to 28% stronger in total intensity. Furthermore, significant radial and azimuthal variations are also detected in the polarization fraction of the disk. In particular, we find that regions of lower polarization fraction are associated with annuli of increased surface brightness, suggesting that the relative proportion of multiple-to-single scattering is greater along the ring and gap structures. Moreover, we find strong (similar to 20%) azimuthal variation in the polarization fraction along the shadowed region of the disk. Further investigation reveals that the azimuthal variation is not the result of disk flaring effects, but is instead from a decrease in the relative contribution of multiple-to-single scattering within the shadowed region. Employing a two-layer scattering surface, we hypothesize that the diminished contribution in multiple scattering may result from shadowing by an inclined inner disk, which prevents direct stellar light from reaching the optically thick underlying surface component.
  • Snowmelt-Driven Trade-Offs Between Early and Late Season Productivity Negatively Impact Forest Carbon Uptake During Drought

    Knowles, John F.; Molotch, Noah P.; Trujillo, Ernesto; Litvak, Marcy E.; Univ Arizona, Sch Geog & Dev (AMER GEOPHYSICAL UNION, 2018-04-16)
    Future projections of declining snowpack and increasing potential evaporation are predicted to advance the timing of snowmelt in mountain ecosystems globally with unknown implications for snowmelt-driven forest productivity. Accordingly, this study combined satellite-and tower-based observations to investigate the forest productivity response to snowpack and potential evaporation variability between 1989 and 2012 throughout the Southern Rocky Mountain ecoregion, United States. Our results show that early and late season productivity were significantly and inversely related and that future shifts toward earlier and/or reduced snowmelt could decrease snowmelt water use efficiency and thus restrict productivity despite a longer growing season. This was explained by increasing snow aridity, which incorporated evaporative demand and snow water supply, and was modified by summer precipitation to determine total annual productivity. The combination of low snow accumulation and record high potential evaporation in 2012 resulted in the 34 year minimum ecosystem productivity that could be indicative of future conditions. Plain Language Summary Snow is melting earlier, and there is potential for greater evaporation as a result of warmer, drier conditions in semiarid mountain regions around the world. These changes combine to affect seasonal moisture availability on the landscape, which is essential to proper ecosystem function. This research used 34 years of satellite-and field-based data that included three distinct droughts to show that forest activity, measured as the amount of carbon dioxide removed from the atmosphere, may decrease as a result of this scenario. This work has broad implications for global climate change since forests in seasonally snow-covered areas currently contribute to mitigating carbon dioxide emissions.
  • SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

    Van Dyk, Schuyler D.; Zheng, WeiKang; Brink, Thomas G.; Filippenko, Alexei V.; Milisavljevic, Dan; Andrews, Jennifer E.; Smith, Nathan; Cignoni, Michele; Fox, Ori D.; Kelly, Patrick L.; Adamo, Angela; Yunus, Sameen; Zhang, Keto; Kumar, Sahana; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-06-20)
    We have identified a progenitor candidate in archival Hubble Space Telescope (HST) images for the Type Ic supernova (SN Ic) SN 2017ein in NGC 3938, pinpointing the candidate's location via HST Target of Opportunity imaging of the SN itself. This would be the first identification of a stellar-like object as a progenitor candidate for any SN Ic to date. We also present observations of SN 2017ein during the first similar to 49 days since explosion. We find that SN 2017ein most resembles the well-studied SN Ic SN 2007gr. We infer that SN 2017ein experienced a total visual extinction of A(V)approximate to 1.0-1.9 mag, predominantly because of dust within the host galaxy. Although the distance is not well known, if this object is the progenitor, it was likely of high initial mass, similar to 47-48M(circle dot) if a single star, or similar to 60-80M(circle dot) if in a binary system. However, we also find that the progenitor candidate could be a very blue and young compact cluster, further implying a very massive (>65M(circle dot)) progenitor. Furthermore, the actual progenitor might not be associated with the candidate at all and could be far less massive. From the immediate stellar environment, we find possible evidence for three different populations; if the SN progenitor was a member of the youngest population, this would be consistent with an initial mass of similar to 57M(circle dot). After it has faded, the SN should be reobserved at high spatial resolution and sensitivity, to determine whether the candidate is indeed the progenitor.
  • SMAP Soil Moisture Change as an Indicator of Drought Conditions

    Rajasekaran, Eswar; Das, Narendra; Poulsen, Calvin; Behrangi, Ali; Swigart, John; Svoboda, Mark; Entekhabi, Dara; Yueh, Simon; Doorn, Bradley; Entin, Jared; Univ Arizona, Dept Hydrol & Atmospher Sci (MDPI, 2018-05)
    Soil moisture is considered a key variable in drought analysis. The soil moisture dynamics given by the change in soil moisture between two time periods can provide information on the intensification or improvement of drought conditions. The aim of this work is to analyze how the soil moisture dynamics respond to changes in drought conditions over multiple time intervals. The change in soil moisture estimated from the Soil Moisture Active Passive (SMAP) satellite observations was compared with the United States Drought Monitor (USDM) and the Standardized Precipitation Index (SPI) over the contiguous United States (CONUS). The results indicated that the soil moisture change over 13-week and 26-week intervals is able to capture the changes in drought intensity levels in the USDM, and the change over a four-week interval correlated well with the one-month SPI values. This suggested that a short-term negative soil moisture change may indicate a lack of precipitation, whereas a persistent long-term negative soil moisture change may indicate severe drought conditions. The results further indicate that the inclusion of soil moisture change will add more value to the existing drought-monitoring products.
  • Sexually dimorphic venom proteins in long-jawed orb-weaving spiders (Tetragnatha) comprise novel gene families

    Zobel-Thropp, Pamela A.; Bulger, Emily A.; Cordes, Matthew H.J.; Binford, Greta J.; Gillespie, Rosemary G.; Brewer, Michael S.; Univ Arizona, Dept Chem & Biochem (PEERJ INC, 2018-06-01)
    Venom has been associated with the ecological success of many groups of organisms, most notably reptiles, gastropods, and arachnids. In some cases, diversification has been directly linked to tailoring of venoms for dietary specialization. Spiders in particular are known for their diverse venoms and wide range of predatory behaviors, although there is much to learn about scales of variation in venom composition and function. The current study focuses on venom characteristics in different sexes within a species of spider. We chose the genus Tetragnatha (Tetragnathidae) because of its unusual courtship behavior involving interlocking of the venom delivering chelicerae (i.e., the jaws), and several species in the genus are already known to have sexually dimorphic venoms. Here, we use transcriptome and proteome analyses to identify venom components that are dimorphic in Tetragnatha versicolor. We present cDNA sequences including unique, male-specific high molecular weight proteins that have remote, if any, detectable similarity to known venom components in spiders or other venomous lineages and have no detectable homologs in existing databases. While the function of these proteins is not known, their presence in association with the cheliceral locking mechanism during mating together with the presence of prolonged male-male mating attempts in a related, cheliceral-locking species (Doryonychus raptor) lacking the dimorphism suggests potential for a role in sexual communication.
  • Gender wage gaps and risky vs. secure employment: An experimental analysis

    Jung, SeEun; Choe, Chung; Oaxaca, Ronald L.; Univ Arizona, PRESAGE, LISER, IZA (ELSEVIER SCIENCE BV, 2018-06)
    In addition to discrimination, market power, and human capital, gender differences in risk preferences might also contribute to observed gender wage gaps. We conduct laboratory experiments in which subjects choose between a risky (in terms of exposure to unemployment) and a secure job after being assigned in early rounds to both types of jobs. Both jobs involve the same typing task. The risky job adds the element of a known probability that the typing opportunity will not be available in any given period. Subjects were informed of the exogenous risk premium being offered for the risky job. Women were more likely than men to select the secure job, and these job choices accounted for between 40% and 77% of the gender wage gap in the experiments. A method for classifying subjects according to risk preferences is derived from the theoretical framework and further demonstrates the higher incidence of risk aversion among women.
  • Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years - Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2014.

    Baio, Jon; Wiggins, Lisa; Christensen, Deborah L; Maenner, Matthew J; Daniels, Julie; Warren, Zachary; Kurzius-Spencer, Margaret; Zahorodny, Walter; Robinson Rosenberg, Cordelia; White, Tiffany; Durkin, Maureen S; Imm, Pamela; Nikolaou, Loizos; Yeargin-Allsopp, Marshalyn; Lee, Li-Ching; Harrington, Rebecca; Lopez, Maya; Fitzgerald, Robert T; Hewitt, Amy; Pettygrove, Sydney; Constantino, John N; Vehorn, Alison; Shenouda, Josephine; Hall-Lande, Jennifer; Van Naarden Braun, Kim; Dowling, Nicole F; Univ Arizona (CENTERS DISEASE CONTROL, 2018-04-27)
    Autism spectrum disorder (ASD). 2014. The Autism and Developmental Disabilities Monitoring (ADDM) Network is an active surveillance system that provides estimates of the prevalence of autism spectrum disorder (ASD) among children aged 8 years whose parents or guardians reside within 11 ADDM sites in the United States (Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin). ADDM surveillance is conducted in two phases. The first phase involves review and abstraction of comprehensive evaluations that were completed by professional service providers in the community. Staff completing record review and abstraction receive extensive training and supervision and are evaluated according to strict reliability standards to certify effective initial training, identify ongoing training needs, and ensure adherence to the prescribed methodology. Record review and abstraction occurs in a variety of data sources ranging from general pediatric health clinics to specialized programs serving children with developmental disabilities. In addition, most of the ADDM sites also review records for children who have received special education services in public schools. In the second phase of the study, all abstracted information is reviewed systematically by experienced clinicians to determine ASD case status. A child is considered to meet the surveillance case definition for ASD if he or she displays behaviors, as described on one or more comprehensive evaluations completed by community-based professional providers, consistent with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) diagnostic criteria for autistic disorder; pervasive developmental disorder-not otherwise specified (PDD-NOS, including atypical autism); or Asperger disorder. This report provides updated ASD prevalence estimates for children aged 8 years during the 2014 surveillance year, on the basis of DSM-IV-TR criteria, and describes characteristics of the population of children with ASD. In 2013, the American Psychiatric Association published the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which made considerable changes to ASD diagnostic criteria. The change in ASD diagnostic criteria might influence ADDM ASD prevalence estimates; therefore, most (85%) of the records used to determine prevalence estimates based on DSM-IV-TR criteria underwent additional review under a newly operationalized surveillance case definition for ASD consistent with the DSM-5 diagnostic criteria. Children meeting this new surveillance case definition could qualify on the basis of one or both of the following criteria, as documented in abstracted comprehensive evaluations: 1) behaviors consistent with the DSM-5 diagnostic features; and/or 2) an ASD diagnosis, whether based on DSM-IV-TR or DSM-5 diagnostic criteria. Stratified comparisons of the number of children meeting either of these two case definitions also are reported. For 2014, the overall prevalence of ASD among the 11 ADDM sites was 16.8 per 1,000 (one in 59) children aged 8 years. Overall ASD prevalence estimates varied among sites, from 13.1-29.3 per 1,000 children aged 8 years. ASD prevalence estimates also varied by sex and race/ethnicity. Males were four times more likely than females to be identified with ASD. Prevalence estimates were higher for non-Hispanic white (henceforth, white) children compared with non-Hispanic black (henceforth, black) children, and both groups were more likely to be identified with ASD compared with Hispanic children. Among the nine sites with sufficient data on intellectual ability, 31% of children with ASD were classified in the range of intellectual disability (intelligence quotient [IQ] <70), 25% were in the borderline range (IQ 71-85), and 44% had IQ scores in the average to above average range (i.e., IQ >85). The distribution of intellectual ability varied by sex and race/ethnicity. Although mention of developmental concerns by age 36 months was documented for 85% of children with ASD, only 42% had a comprehensive evaluation on record by age 36 months. The median age of earliest known ASD diagnosis was 52 months and did not differ significantly by sex or race/ethnicity. For the targeted comparison of DSM-IV-TR and DSM-5 results, the number and characteristics of children meeting the newly operationalized DSM-5 case definition for ASD were similar to those meeting the DSM-IV-TR case definition, with DSM-IV-TR case counts exceeding DSM-5 counts by less than 5% and approximately 86% overlap between the two case definitions (kappa = 0.85).
  • Scintillator performance considerations for dedicated breast computed tomography

    Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; Univ Arizona, Dept Med Imaging (SPIE-INT SOC OPTICAL ENGINEERING, 2017)
    Dedicated breast computed tomography (BCT) is an emerging clinical modality that can eliminate tissue superposition and has the potential for improved sensitivity and specificity for breast cancer detection and diagnosis. It is performed without physical compression of the breast. Most of the dedicated BCT systems use large-area detectors operating in cone-beam geometry and are referred to as cone-beam breast CT (CBBCT) systems. The large-area detectors in CBBCT systems are energy-integrating, indirect-type detectors employing a scintillator that converts x-ray photons to light, followed by detection of optical photons. A key consideration that determines the image quality achieved by such CBBCT systems is the choice of scintillator and its performance characteristics. In this work, a framework for analyzing the impact of the scintillator on CBBCT performance and its use for task-specific optimization of CBBCT imaging performance is described.
  • Scaling and universality in extremal black hole perturbations

    Gralla, Samuel E.; Zimmerman, Peter; Univ Arizona, Dept Phys (SPRINGER, 2018-06-12)
    We show that the emergent near-horizon conformal symmetry of extremal black holes gives rise to universal behavior in perturbing fields, both near and far from the black hole horizon. The scale-invariance of the near-horizon region entails power law time-dependence with three universal features: (1) the decay off the horizon is always precisely twice as fast as the decay on the horizon; (2) the special rates of 1/t off the horizon and 1/root v on the horizon commonly occur; and (3) sufficiently high-order transverse derivatives grow on the horizon (Aretakis instability). The results are simply understood in terms of near-horizon (AdS(2)) holography. We first show how the general features follow from symmetry alone and then go on to present the detailed universal behavior of scalar, electromagnetic, and gravitational perturbations of d-dimensional electrovacuum black holes.
  • Saturation of VCMA in out-of-plane magnetized CoFeB/MgO/CoFeB magnetic tunnel junctions

    Williamson, M.; de Rozieres, M.; Almasi, H.; Chao, X.; Wang, W.; Wang, J.-P.; Tsoi, M.; Univ Arizona, Dept Phys (AMER INST PHYSICS, 2018-05)
    Voltage controlled magnetic anisotropy (VCMA) currently attracts considerable attention as a novel method to control and manipulate magnetic moments in high-speed and low-power spintronic applications based on magnetic tunnel junctions (MTJs). In our experiments, we use ferromagnetic resonance (FMR) to study and quantify VCMA in out-of-plane magnetized CoFeB/MgO/CoFeB MTJ pillars. FMR is excited by applying a microwave current and detected via a small rectified voltage which develops across MTJ at resonance. The VCMA effective field can be extracted from the measured resonance field and was found to vary as a function of electrical bias applied to MTJ. At low applied biases, we observe a linear shift of the VCMA field as a function of the applied voltage which is consistent with the VCMA picture based on the bias-induced electron migration across the MgO/CoFeB interface. At higher biases, both positive and negative, we observe a deviation from the linear behavior which may indicate a saturation of the VCMA effect. These results are important for the design of MTJ-based applications. (C) 2017 Author(s).
  • Rho-kinase inhibitors do not expand hematoma volume in acute experimental intracerebral hemorrhage

    Akhter, Murtaza; Qin, Tom; Fischer, Paul; Sadeghian, Homa; Kim, Hyung Hwan; Whalen, Michael J.; Goldstein, Joshua N.; Ayata, Cenk; Univ Arizona, Coll Med Phoenix, Maricopa Med Ctr, Dept Emergency Med (WILEY, 2018-06)
    Rho-associated kinase (ROCK) is an emerging target in acute ischemic stroke. Early pre-hospital treatment with ROCK inhibitors may improve their efficacy, but their antithrombotic effects raise safety concerns in hemorrhagic stroke, precluding use prior to neuroimaging. Therefore, we tested whether ROCK inhibition affects the bleeding times, and worsens hematoma volume in a model of intracerebral hemorrhage (ICH) induced by intrastriatal collagenase injection in mice. Tail bleeding time was measured 1 h after treatment with isoform-nonselective inhibitor fasudil, or ROCK2-selective inhibitor KD025, or their vehicles. In the ICH model, treatments were administered 1 h after collagenase injection. Although KD025 but not fasudil prolonged the tail bleeding times, neither drug expanded the volume of ICH or worsened neurological deficits at 48 h compared with vehicle. Although more testing is needed in aged animals and comorbid models such as diabetes, these results suggest ROCK inhibitors may be safe for pre-hospital administration in acute stroke.
  • RELICS: Strong Lens Models for Five Galaxy Clusters from the Reionization Lensing Cluster Survey

    Cerny, Catherine; Sharon, Keren; Andrade-Santos, Felipe; Avila, Roberto J.; Bradač, Maruša; Bradley, Larry D.; Carrasco, Daniela; Coe, Dan; Czakon, Nicole G.; Dawson, William A.; Frye, Brenda L.; Hoag, Austin; Huang, Kuang-Han; Johnson, Traci L.; Jones, Christine; Lam, Daniel; Lovisari, Lorenzo; Mainali, Ramesh; Oesch, Pascal A.; Ogaz, Sara; Past, Matthew; Paterno-Mahler, Rachel; Peterson, Avery; Riess, Adam G.; Rodney, Steven A.; Ryan, Russell E.; Salmon, Brett; Sendra-Server, Irene; Stark, Daniel P.; Strolger, Louis-Gregory; Trenti, Michele; Umetsu, Keiichi; Vulcani, Benedetta; Zitrin, Adi; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-06-01)
    Strong gravitational lensing by galaxy clusters magnifies background galaxies, enhancing our ability to discover statistically significant samples of galaxies at z > 6, in order to constrain the high-redshift galaxy luminosity functions. Here, we present the first five lens models out of the Reionization Lensing Cluster Survey (RELICS) Hubble Treasury Program, based on new HST WFC3/IR and ACS imaging of the clusters RXC J0142.9+4438, Abell 2537, Abell 2163, RXC J2211.7-0349, and ACT-C110102-49151. The derived lensing magnification is essential for estimating the intrinsic properties of high-redshift galaxy candidates, and properly accounting for the survey volume. We report on new spectroscopic redshifts of multiply imaged lensed galaxies behind these clusters, which are used as constraints, and detail our strategy to reduce systematic uncertainties due to lack of spectroscopic information. In addition, we quantify the uncertainty on the lensing magnification due to statistical and systematic errors related to the lens modeling process, and find that in all but one cluster, the magnification is constrained to better than 20% in at least 80% of the field of view, including statistical and systematic uncertainties. The five clusters presented in this paper span the range of masses and redshifts of the clusters in the RELICS program. We find that they exhibit similar strong lensing efficiencies to the clusters targeted by the Hubble Frontier Fields within the WFC3/IR field of view. Outputs of the lens models are made available to the community through the Mikulski Archive for Space Telescopes.
  • Reduction in terminally differentiated T cells in virologically controlled HIV-infected aging patients on long-term antiretroviral therapy

    Behrens, Nicole E.; Wertheimer, Anne; Klotz, Stephen A.; Ahmad, Nafees; Univ Arizona, Coll Med, Dept Immunobiol; Univ Arizona, Coll Med, Dept Med; Univ Arizona, Inst Bio5 (PUBLIC LIBRARY SCIENCE, 2018-06-13)
    Several studies have shown an increased accumulation of terminally differentiated T cells during HIV infection, suggestive of exhaustion/senescence, causing dysregulation of T cell homeostasis and function and rapid HIV disease progression. We have investigated whether long-term antiretroviral therapy (ART), which controls viremia and restores CD4 T cell counts, is correlated with reduction in terminally differentiated T cells, improved ratios of na ve to memory and function of T cells in 100 virologically controlled HIV-infected patients. We show that while the median frequencies of terminally differentiated CD4(+) and CD8(+) T cells (CD28(-), CD27(-), CD57(+) and CD28-CD57(+)), were higher in the virologically controlled HIV-infected patients' cohort compared with uninfected individuals' cohort, the frequencies of these cells significantly decreased with increasing CD4 T cell counts in HIV-infected patients. Although, the naive CD4+ and CD8+ T cells were lower in HIV patients' cohort than uninfected cohort, there was a significant increase in both na ve CD4(+) and CD8(+) T cells with increasing CD4 T cell counts in HIV-infected patients. The underlying mechanism behind this increased naive CD4(+) and CD8(+) T cells in HIV-infected patients was due to an increase in recent thymic emigrants, CD4(+)CD31(+), as compared to CD4(+)CD31(-). The CD4+ T cells of HIV-infected patients produced cytokines, including IL-2, IL-10 and IFN-gamma comparable to uninfected individuals. In conclusion, virologically controlled HIV-infected patients on longterm ART show a significant reduction in terminally differentiated T cells, suggestive of decreased exhaustion/senescence, and improvement in the ratios of na ve to memory and function of T cells.
  • Random two-step phase shifting interferometry based on Lissajous ellipse fitting and least squares technologies

    Zhang, Yu; Tian, Xiaobo; Liang, Rongguang; Univ Arizona, Coll Opt Sci (OPTICAL SOC AMER, 2018-06-11)
    To accurately obtain the phase distribution of an optical surface under test, the accurate phase extraction algorithm is essential. To overcome the phase shift error, a random two-step phase shifting algorithm, which can be used in the fluctuating and non-uniform background intensity and modulation amplitude, Lissajous ellipse fitting, and least squares iterative phase shifting algorithm (LEF&LSI PSA), is proposed; pre-filtering interferograms are not necessary, but they can get relatively accurate phase distribution and unknown phase shift value. The simulation and experiment verify the correctness and feasibility of the LEF & LSI PSA. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
  • Quantum antenna arrays: The role of quantum interference on direction-dependent photon statistics

    Liberal, Iñigo; Ederra, Iñigo; Ziolkowski, Richard W.; Univ Arizona, Dept Elect & Comp Engn (AMER PHYSICAL SOC, 2018-05-31)
    We investigate the role of quantum interference phenomena on the characteristics of the fields radiated by an array of quantum emitters. In analogy to, but distinct from, classical outcomes, we demonstrate that the array geometry empowers control over direction-dependent photon statistics of arbitrary order. Our formulation enables the recognition of configurations providing spatial correlations with no classical counterpart. For example, we identify a system in which the angular distribution of the average number of photons is independent of the number and position of the emitters, while its higher-order photon statistics exhibit a directional behavior. These results extend our understanding of the fields generated by ensembles of quantum emitters, with potential applications to nonclassical light sources.
  • Provitamin A biofortification of cassava enhances shelf life but reduces dry matter content of storage roots due to altered carbon partitioning into starch

    Beyene, Getu; Solomon, Felix R.; Chauhan, Raj D.; Gaitán-Solis, Eliana; Narayanan, Narayanan; Gehan, Jackson; Siritunga, Dimuth; Stevens, Robyn L.; Jifon, John; Van Eck, Joyce; Linsler, Edward; Gehan, Malia; Ilyas, Muhammad; Fregene, Martin; Sayre, Richard T.; Anderson, Paul; Taylor, Nigel J.; Cahoon, Edgar B.; Univ Arizona (WILEY, 2018-06)
    Storage roots of cassava (Manihot esculenta Crantz), a major subsistence crop of sub-Saharan Africa, are calorie rich but deficient in essential micronutrients, including provitamin A beta-carotene. In this study, beta-carotene concentrations in cassava storage roots were enhanced by co-expression of transgenes for deoxy-D-xylulose-5-phosphate synthase (DXS) and bacterial phytoene synthase (crtB), mediated by the patatin-type 1 promoter. Storage roots harvested from field-grown plants accumulated carotenoids to <= 50 mu g/g DW, 15- to 20-fold increases relative to roots from nontransgenic plants. Approximately 85%-90% of these carotenoids accumulated as all-trans-beta-carotene, the most nutritionally efficacious carotenoid. beta-Carotene-accumulating storage roots displayed delayed onset of postharvest physiological deterioration, a major constraint limiting utilization of cassava products. Large metabolite changes were detected in beta-carotene-enhanced storage roots. Most significantly, an inverse correlation was observed between beta-carotene and dry matter content, with reductions of 50%-60% of dry matter content in the highest carotenoid-accumulating storage roots of different cultivars. Further analysis confirmed a concomitant reduction in starch content and increased levels of total fatty acids, triacylglycerols, soluble sugars and abscisic acid. Potato engineered to co-express DXS and crtB displayed a similar correlation between b-carotene accumulation, reduced dry matter and starch content and elevated oil and soluble sugars in tubers. Transcriptome analyses revealed a reduced expression of genes involved in starch biosynthesis including ADP-glucose pyrophosphorylase genes in transgenic, carotene-accumulating cassava roots relative to nontransgenic roots. These findings highlight unintended metabolic consequences of provitamin A biofortification of starch-rich organs and point to strategies for redirecting metabolic flux to restore starch production.
  • Protoplanetary Disk Properties in the Orion Nebula Cluster: Initial Results from Deep, High-resolution ALMA Observations

    Eisner, J. A.; Arce, H. G.; Ballering, N. P.; Bally, J.; Andrews, S. M.; Boyden, R. D.; Francesco, J. Di; Fang, M.; Johnstone, D.; Kim, J. S.; Mann, R. K.; Matthews, B.; Pascucci, I.; Ricci, L.; Sheehan, P. D.; Williams, J. P.; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2018-06-10)
    We present Atacama Large Millimeter Array 850 mu m continuum observations of the Orion Nebula Cluster that provide the highest angular resolution (similar to 0."1 approximate to 40 au) and deepest sensitivity (similar to 0.1 mJy) of the region to date. We mosaicked a field containing similar to 225 optical or near-IR-identified young stars, similar to 60 of which are also optically identified "proplyds." We detect continuum emission at 850 mu m toward similar to 80% of the proplyd sample, and similar to 50% of the larger sample of previously identified cluster members. Detected objects have fluxes of similar to 0.5-80 mJy. We remove submillimeter flux due to free-free emission in some objects, leaving a sample of sources detected in dust emission. Under standard assumptions of isothermal, optically thin disks, submillimeter fluxes correspond to dust masses of similar to 0.5-80 Earth masses. We measure the distribution of disk sizes, and find that disks in this region are particularly compact. Such compact disks are likely to be significantly optically thick. The distributions of submillimeter flux and inferred disk size indicate smaller, lower-flux disks than in lower-density star-forming regions of similar age. Measured disk flux is correlated weakly with stellar mass, contrary to studies in other star-forming regions that found steeper correlations. We find a correlation between disk flux and distance from the massive star theta(1) Ori C, suggesting that disk properties in this region are influenced strongly by the rich cluster environment.

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