466 research outputs found

    The dark matter halos of the bluest low surface brightness galaxies

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    We present BVI photometry and long-slit Halpha rotation curve data obtained with ESO VLT/FORS2 for six low surface brightness galaxies with extremely blue colours and very faint central regions. We find no evidence for a steep central density cusp of the type predicted by many N-body simulations of cold dark matter (CDM) halos. Our observations are instead consistent with dark matter halos characterized by cores of roughly constant density, in agreement with previous investigations. While unremarkable in terms of the central density slope, these galaxies appear very challenging for existing CDM halo models in terms of average central halo density, as measured by the Delta_(V/2) parameter. Since most of our target galaxies are bulgeless disks, our observations also disfavour a recently suggested mechanism for lowering the central mass concentration of the halo by means of a fast collapse phase, as this scenario predicts that the original CDM profile should still be detectable in bulgeless galaxies. Other potential ways of reconciling the CDM predictions with these observations are discussed.Comment: 14 pages, 9 figures, accepted for publication in Astronomy & Astrophysic

    Water-Conserving Landscapes: An Evaluation of Homeowner Preference

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    Landscape preferences were assessed for three identically designed Xeriscapes™, differing only in the plant material, under both well-watered and drought conditions. The classes of plant material included traditional (high water use), intermediate (moderate water use), and native/adapted plant species of the Intermountain West (low water use). Landscapes were subjected to a 5-week dry-down period. Under drought conditions, respondents preferred drought/adapted and intermediate landscapes to traditional landscapes. A focus on Xeriscape™ education, practices, and visual exposure may result in greater adoption of Xeriscape™ practices by homeowners and may also result in significant residential water savings

    Water-conserving landscapes: an evaluation of homeowner preference

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    Landscape preferences were assessed for three identically designed Xeriscapes™, differing only in the plant material, under both well-watered and drought conditions. The classes of plant material included traditional (high water use), intermediate (moderate water use), and native/adapted plant species of the Intermountain West (low water use). Landscapes were subjected to a 5-week dry-down period. Under drought conditions, respondents preferred drought/adapted and intermediate landscapes to traditional landscapes. A focus on Xeriscape™ education, practices, and visual exposure may result in greater adoption of Xeriscape™ practices by homeowners and may also result in significant residential water savings

    Karlstadter Positionspapier zum Schutz der Ackerwildkräuter. Erarbeitet von den Teilnehmerinnen und Teilnehmern der "Tagung zum Schutz der Ackerwildflora" am 25./26.6.2004 in Karlstadt am Main

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    Der Erhalt von Ackerwildkräutern, die historisch erst mit der Landbewirtschaftung in Mitteleuropa heimisch geworden sind, ist eine Kulturaufgabe, damit auch künftige Generationen die Arten- und Farbenvielfalt in der Kulturlandschaft erleben können

    Efficacy of Online Training for Improving Camp Staff Competency

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    Preparing competent staff is a critical issue within the camp community. This quasi-experimental study examined the effectiveness of an online course for improving staff competency in camp healthcare practices among college-aged camp staff and a comparison group (N = 55). We hypothesized that working in camp would increase competency test scores due to opportunities for staff to experientially apply knowledge learned online. Hierarchical linear modeling was used to analyse the cross-level effects of a between-individuals factor (assignment to experimental or comparison group) and within-individual effects of time (pre-test, post-test #1, and post-test #2) on online course test scores. At post-test #2, the difference in average test scores between groups was ~30 points, with the treatment group scoring lower on average than the comparison group. Factors that may have influenced these findings are explored, including fatigue and the limited durability of online learning. Recommendations for research and practice are discussed

    Concept and optical design of the cross-disperser module for CRIRES

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    This is the peer reviewed version of the following article: Oliva, Ernesto, A. Tozzi, D. Ferruzzi, L. Origlia, A. Hatzes, R. Follert, T. Loewinger et al. "Concept and optical design of the cross-disperser module for CRIRES+." In SPIE Astronomical Telescopes+ Instrumentation, pp. 91477R-91477R. International Society for Optics and Photonics, 2014, which has been published in final form at 10.1117/12.2054381
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