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Now showing 1 - 5 of 47
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    Promoting Transformative Learning Using Critical Pedagogy and Moore's Theory of Transactional Distance
    (Peter Lang, 2022-08-11) Donaldson, Sara; Yuhaniak, Heather; Borkoski, Carey; Abel, Yolanda
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    Multiwavelength Observations Reveal a Faint Candidate Black Hole X-Ray Binary in IGR J17285−2922.
    (Oxford University Press, 2021-07-24) Stoop, M.; van den Eijnden, J.; N. Degenaar; Bahramian, A.; Swihart, S. J.; Strader, J.; Jimenez-Ibarra, F.; Munoz-Darias, T.; M. Armas Padilla. M.; Shaw, A. W.; Maccarone, T.J.; Wijnands, R.; Russell, T. D.; Hernandez Santisteban, J. V.; Miller-Jones, J. C. A.; Russell, D. M.; Maitra, D.; Heinke, C. O.; Sivakoff, G. R.; Lewis, F.; Bramich, D. M.
    IGR J17285−2922 is a known X-ray binary with a low peak 2–10 keV X-ray luminosity of ∼ 1036 erg s−1 during outburst. IGR J17285−2922 exhibited two outbursts in 2003 and 2010 and went into outburst again in 2019. We have monitored this ∼ 4-month long 2019 outburst with Swift in X-ray and the Very Large Array in radio. We have also obtained four optical spectra with the Gran Telescopio Canarias and Southern Astrophysical Research Telescope, three optical photometry measurements with the Las Cumbres Observatory, and one near-infrared spectrum with the Gemini South telescope. The ratio between its X-ray and radio luminosity is consistent with both samples of neutron star and black hole (BH) X-ray binaries, while the ratio between the X-ray and optical luminosity is consistent with BH X-ray binaries. Studying the evolution of its X-ray power-law index throughout the outburst, we find additional evidence for a BH as compact object. The four optical spectra show no H α emission and the nIR spectrum shows no Brγ emission, suggesting that the donor star could be hydrogen-poor and hence that IGR J17285−2922 might have an ultracompact binary orbit. The shape of the X-ray light curve is well described by an exponential, followed by a linear decay, from which we obtain a relation between the orbital period Porb and the binary mass ratio. We discuss how this relation is consistent with theoretical predictions and known ultracompact X-ray binaries. Lastly, we discuss how the observed properties are reminiscent of short-Porb BH X-ray binaries.
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    Birds and Bioenergy within the Americas: A Cross-National, Social–Ecological Study of Ecosystem Service Tradeoffs
    (MPDI, 2021-03-03) Knowlton, Jessie.L.; Halvorsen, Kathleen.E.; Flaspohler, David J.; Webster, Christopher.R.; Abrams, Jesse; Almeida, Sara.M.; Arriaga-Weiss, Stefan L.; Barnett, Brad; Cardoso, Maíra R.; Cerqueira, Pablo V.; Córdoba, Diana; Persio Dantas-Santos, Marcos; Dunn, Jennifer L.; Eastmond, Amarella; Jarvi, Gina M.; Licara, Julian A.; Mata-Zayas, Ena; Medeiros, Rodrigo; Azahara Mesa-Jurado, M.; Yamily Moo-Culebro, Lízbeth; Moseley, Cassandra; Nielsen, Erik; Phifer, Colin C.; Pischke, Erin C.; Schelly, Chelsea; Selfa, Theresa; Silva, Chelsea A.; Souza, Tatiana; Sweitz, Samuel R.; Vázquez-Navarrete, César J.
    Although renewable energy holds great promise in mitigating climate change, there are socioeconomic and ecological tradeoffs related to each form of renewable energy. Forest-related bioenergy is especially controversial, because tree plantations often replace land that could be used to grow food crops and can have negative impacts on biodiversity. In this study, we examined public perceptions and ecosystem service tradeoffs between the provisioning services associated with cover types associated with bioenergy crop (feedstock) production and forest habitat-related supporting services for birds, which themselves provide cultural and regulating services. We combined a social survey-based assessment of local values and perceptions with measures of bioenergy feedstock production impacts on bird habitat in four countries: Argentina, Brazil, Mexico, and the USA. Respondents in all countries rated birds as important or very important (83–99% of respondents) and showed lower enthusiasm for, but still supported, the expansion of bioenergy feedstocks (48–60% of respondents). Bioenergy feedstock cover types in Brazil and Argentina had the greatest negative impact on birds but had a positive impact on birds in the USA. In Brazil and Mexico, public perceptions aligned fairly well with the realities of the impacts of potential bioenergy feedstocks on bird communities. However, in Argentina and the USA, perceptions of bioenergy impacts on birds did not match well with the data. Understanding people’s values and perceptions can help inform better policy and management decisions regarding land use changes.
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    A new radio census of neutron star X-ray binaries
    (Oxford University Press, 2021-07-21) van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Wijnands, R.; Bahramian, A.; Miller-Jones, J. C. A.; Hernandez Santisteban, J. V.; Gallo, E.; Atri, P.; Plotkin, R. M.; Maccarone, T. J.; Sivakoff, G.; Miller, J. M.; Reynolds, M.; Russell, D. M.; Maitra, D.; Heinke, C. O.; Armas Padilla, M.; Shaw, A. W.
    We report new radio observations of a sample of 36 neutron star (NS) X-ray binaries, more than doubling the sample in the literature observed at current-day sensitivities. These sources include 13 weakly magnetized (B < 1010 G) and 23 strongly magnetized (B ≥ 1010 G) NSs. 16 of the latter category reside in high-mass X-ray binaries, of which only two systems were radio-detected previously. We detect four weakly and nine strongly magnetized NSs; the latter are systematically radio fainter than the former and do not exceed LR ≈ 3 × 1028 erg s−1. In turn, we confirm the earlier finding that the weakly magnetized NSs are typically radio fainter than accreting stellar-mass black holes. While an unambiguous identification of the origin of radio emission in high-mass X-ray binaries is challenging, we find that in all but two detected sources (Vela X-1 and 4U 1700-37) the radio emission appears more likely attributable to a jet than the donor star wind. The strongly magnetized NS sample does not reveal a global correlation between X-ray and radio luminosity, which may be a result of sensitivity limits. Furthermore, we discuss the effect of NS spin and magnetic field on radio luminosity and jet power in our sample. No current model can account for all observed properties, necessitating the development and refinement of NS jet models to include magnetic field strengths up to 1013 G. Finally, we discuss jet quenching in soft states of NS low-mass X-ray binaries, the radio non-detections of all observed very-faint X-ray binaries in our sample, and future radio campaigns of accreting NSs.
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    Reporting is not supporting: Why mandatory supporting, not mandatory reporting, must guide university sexual misconduct policies
    (At The National Academies, 2021-12-22) Holland, Kathryn J.; Hutchison, Elizabeth Q.; Ahrens, Courtney E.; Gabriela Torres, M.