Now showing items 1321-1340 of 12955

    • The [C ii]/[N ii] ratio in 3< z< 6 sub-millimetre galaxies from the South Pole Telescope survey

      Cunningham, D J M; Chapman, S C; Aravena, M; De Breuck, C; Béthermin, M; Chen, Chian-Chou; Dong, Chenxing; Gonzalez, A H; Greve, T R; Litke, K C; et al. (OXFORD UNIV PRESS, 2020-03-30)
      We present Atacama Compact Array and Atacama Pathfinder Experiment observations of the [N II] 205 mu m fine-structure line in 40 sub-millimetre galaxies lying at redshifts z = 3-6, drawn from the 2500 deg(2) South Pole Thlescope survey. This represents the largest uniformly selected sample of high-redshift [N II] 205 mu m measurements to date. 29 sources also have [C II] 158 mu m line observations allowing a characterization of the distribution of the [C II] to [N II] luminosity ratio for the first time at high redshift. The sample exhibits a median L[C II] /L [N II]) approximate to 11.0 and interquartile range of 5.0 -24.7. These ratios are similar to those observed in local (Ultra)luminous infrared galaxies (LIRGs), possibly indicating similarities in their interstellar medium. At the extremes, we find individual sub-millimetre galaxies with L[C II]/L [N II] low enough to suggest a smaller contribution from neutral gas than ionized gas to the [C II] flux and high enough to suggest strongly photon or X-ray region dominated flux. These results highlight a large range in this line luminosity ratio for sub-millimetre galaxies, which may be caused by variations in gas density, the relative abundances of carbon and nitrogen, ionization parameter, metallicity, and a variation in the fractional abundance of ionized and neutral interstellar medium.
    • 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.
    • C-terminal modified Enkephalin-like tetrapeptides with enhanced affinities at the kappa opioid receptor and monoamine transporters

      Mehr-un-Nisa; Munawar, Munawar A.; Rankin, David; Hruby, Victor J.; Porreca, Frank; Lee, Yeon Sun; Department of Chemistry and Biochemistry, University of Arizona; Department of Pharmacology, University of Arizona (Elsevier BV, 2021-12)
      A new series of enkephalin-like tetrapeptide analogs modified at the C-terminus by an N-(3,4-dichlorophenyl)-N-(piperidin-4-yl)propionamide (DPP) moiety were designed, synthesized, and tested for their binding affinities at opioid receptors and monoamine transporters to evaluate their potential multifunctional activity for the treatment of chronic pain. Most ligands exhibited high binding affinities in the nanomolar range at the opioid receptors with a slight delta-opioid receptor (DOR) selectivity over mu-opioid receptor (MOR) and kappa-opioid receptor (KOR) and low binding affinities in the micromolar range at the monoamine transporters, SERT and NET. Ligands of which the positions 1 and 4 were substituted by Dmt and Phe(4-X) residues, respectively, showed the excellent binding affinities at three opioid receptors. Among them, Dmt-D-Tic-Gly-Phe(4-F)-DPP was the most promising considering its excellent opioid affinities, particularly unexpected high binding affinity (Ki = 0.13 nM) at the KOR, and moderate interactions with serotonin/norepinephrine reuptake inhibitors (SNRIs). Docking studies revealed that the ligand was a good fit for the KOR binding pocket (binding score = 8,750).
    • 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.
    • CABra: A novel large-sample dataset for Brazilian catchments

      Almagro, A.; Oliveira, P.T.S.; Meira Neto, A.A.; Roy, T.; Troch, P.; Department of Hydrology and Atmospheric Sciences, University of Arizona (Copernicus GmbH, 2021)
      In this paper, we present the Catchments Attributes for Brazil (CABra), which is a large-sample dataset for Brazilian catchments that includes long-term data (30 years) for 735 catchments in eight main catchment attribute classes (climate, streamflow, groundwater, geology, soil, topography, land cover, and hydrologic disturbance). We have collected and synthesized data from multiple sources (ground stations, remote sensing, and gridded datasets). To prepare the dataset, we delineated all the catchments using the Multi-Error-Removed Improved-Terrain Digital Elevation Model (MERIT DEM) and the coordinates of the streamflow stations provided by the Brazilian Water Agency, where only the stations with 30 years (1980-2010) of data and less than 10% of missing records were included. Catchment areas range from 9 to 4 800 000 km2, and the mean daily streamflow varies from 0.02 to 9mmd-1. Several signatures and indices were calculated based on the climate and streamflow data. Additionally, our dataset includes boundary shapefiles, geographic coordinates, and drainage area for each catchment, aside from more than 100 attributes within the attribute classes. The collection and processing methods are discussed, along with the limitations for each of our multiple data sources. CABra intends to improve the hydrology-related data collection in Brazil and pave the way for a better understanding of different hydrologic drivers related to climate, landscape, and hydrology, which is particularly important in Brazil, having continentalscale river basins and widely heterogeneous landscape characteristics. In addition to benefitting catchment hydrology investigations, CABra will expand the exploration of novel hydrologic hypotheses and thereby advance our understanding of Brazilian catchments' behavior. The dataset is freely available at and access: 7 June 2021). © 2021 André Almagro et al.
    • 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.
    • Cadherin repeat 5 mutation associated with Bt resistance in a field-derived strain of pink bollworm

      Wang, Ling; Ma, Yuemin; Wei, Wei; Wan, Peng; Liu, Kaiyu; Xu, Min; Cong, Shengbo; Wang, Jintao; Xu, Dong; Xiao, Yutao; et al. (NATURE RESEARCH, 2020-10-08)
      Evolution of resistance by pests reduces the benefits of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Here we analyzed resistance to Bt toxin Cry1Ac in a field-derived strain of pink bollworm (Pectinophora gossypiella), a global pest of cotton. We discovered that the r14 allele of the pink bollworm cadherin gene (PgCad1) has a 234-bp insertion in exon 12 encoding a mutant PgCad1 protein that lacks 36 amino acids in cadherin repeat 5 (CR5). A strain homozygous for this allele had 237-fold resistance to Cry1Ac, 1.8-fold cross-resistance to Cry2Ab, and developed from neonate to adult on Bt cotton producing Cry1Ac. Inheritance of resistance to Cry1Ac was recessive and tightly linked with r14. PgCad1 transcript abundance in midgut tissues did not differ between resistant and susceptible larvae. Toxicity of Cry1Ac to transformed insect cells was lower for cells expressing r14 than for cells expressing wild-type PgCad1. Wild-type PgCad1 was transported to the cell membrane, whereas PgCad1 produced by r14 was not. In larval midgut tissue, PgCad1 protein occurred primarily on the brush border membrane only in susceptible larvae. The results imply r14 mediates pink bollworm resistance to Cry1Ac by reduced translation, increased degradation, and/or mislocalization of cadherin.
    • 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 canopy stomatal conductance from eddy covariance measurements, in light of the energy budget closure problem

      Wehr, R.; Saleska, S.R.; Ecology and Evolutionary Biology, University of Arizona (Copernicus GmbH, 2021)
      Canopy stomatal conductance is commonly estimated from eddy covariance measurements of the latent heat flux (LE) by inverting the Penman-Monteith equation. That method ignores eddy covariance measurements of the sensible heat flux (H) and instead calculates H implicitly as the residual of all other terms in the site energy budget. Here we show that canopy stomatal conductance is more accurately calculated from eddy covariance (EC) measurements of both H and LE using the flux-gradient equations that define conductance and underlie the Penman-Monteith equation, especially when the site energy budget fails to close due to pervasive biases in the eddy fluxes and/or the available energy. The flux-gradient formulation dispenses with unnecessary assumptions, is conceptually simpler, and is as or more accurate in all plausible scenarios. The inverted Penman-Monteith equation, on the other hand, contributes substantial biases and erroneous spatial and temporal patterns to canopy stomatal conductance, skewing its relationships with drivers such as light and vapor pressure deficit. © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.
    • 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.
    • Calculating the Higgs mass in string theory

      Abel, S.; Dienes, K.R.; Department of Physics, University of Arizona (American Physical Society, 2021)
      In this paper, we establish a fully string-theoretic framework for calculating one-loop Higgs masses directly from first principles in perturbative closed-string theories. Our framework makes no assumptions other than world sheet modular invariance and is therefore applicable to all closed strings, regardless of the specific string construction utilized. This framework can also be employed even when spacetime supersymmetry is broken (and even when this breaking occurs at the Planck scale), and can be utilized for all scalar Higgs fields, regardless of the particular gauge symmetries they break. This therefore includes the Higgs field responsible for electroweak symmetry breaking in the Standard Model. Notably, using our framework, we demonstrate that a gravitational modular anomaly generically relates the Higgs mass to the one-loop cosmological constant, thereby yielding a string-theoretic connection between the two fundamental quantities which are known to suffer from hierarchy problems in the absence of spacetime supersymmetry. We also discuss a number of crucial issues involving the use and interpretation of regulators in UV/IR-mixed theories such as string theory, and the manner in which one can extract an effective field theory (EFT) description from such theories. Finally, we analyze the running of the Higgs mass within such an EFT description, and uncover the existence of a "dual IR"region which emerges at high energies as the consequence of an intriguing scale-inversion duality symmetry. We also identify a generic stringy effective potential for the Higgs fields in such theories. Our results can therefore serve as the launching point for a rigorous investigation of gauge hierarchy problems in string theory. © 2021 authors. Published by the American Physical Society.
    • Calculations and analysis of 55Mn nuclear quadrupole coupling for asymmetric top acyl methyl manganese pentacarbonyl

      Tanjaroon, Chakree; Mills, David D.; Jiménez Hoyos, Carlos A.; Kukolich, Stephen G.; Univ Arizona, Dept Chem & Biochem (ELSEVIER SCIENCE BV, 2021-01)
      Revised assignments of the measured transitions for the asymmetric top acyl isomers of methyl manganese pentacarbonyl are presented, along with a corresponding fit to determine rotational and quadrupole coupling constants. New assignments for measured transitions give a better fit to the spectrum and better agreement between experimental and calculated quadrupole coupling strengths. The best agreements were obtained for B3LYP and M11 DFT calculations with triple and quadruple-zeta basis sets. Experimental molecular parameters from the new analysis are: A = 840.0843(52), B = 774.2861(17), C = 625.6528(13). DJ = 0.000212(21). DJK = 0.00488(18), 1.5χaa = −46.96(11), 0.25(χbb - χcc) = -13.44(3) MHz.
    • 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.