1722 research outputs found
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Oxo Crater on (1) Ceres: Geological History and the Role of Water-ice
Get PDFDwarf planet Ceres (∅ ∼ 940 km) is the largest object in the main asteroid belt. Investigations suggest that Ceres is a thermally evolved, volatile-rich body with potential geological activity, a body that was never completely molten, but one that possibly partially differentiated into a rocky core and an ice-rich mantle, and may contain remnant internal liquid water. Thermal alteration and the infall of exogenic material contribute to producing a (dark) carbonaceous chondritic-like surface containing ammoniated phyllosilicates. Here we report imaging and spectroscopic analyses of data on the bright Oxo crater derived from the Framing Camera and the Visible and Infrared Spectrometer on board the Dawn spacecraft. We confirm that the transitional complex crater Oxo (∅ ∼ 9 km) exhibits exposed surface water-ice. We show that this water-ice-rich material is associated exclusively with two lobate deposits at pole-facing scarps, deposits that also contain carbonates and admixed phyllosilicates. Due to Oxo’s location at −4802 m below the cerean reference ellipsoid and its very young age of only 190 ka (1σ: +100 ka, −70 ka), Oxo is predestined for ongoing water-ice sublimation.The Framing Camera project is financially supported by the Max Planck Society and the
German Space Agency, DLR.http://iopscience.iop.org/article/10.3847/1538-3881/aa7a04/met
Submicroscopic metallic iron in lunar soils estimated from the in situ spectra of the Chang’E-3 mission
Get PDFSubmicroscopic metallic iron (SMFe) created by space weathering has strong effects on the optical properties of the lunar surface. Spectra measured in situ by the visible-near-infrared spectrometer (VNIS) on board the Chang’E-3 Yutu rover were used to investigate optical maturity differences at the CE-3 landing site caused by lander exhaust. SMFe abundances were estimated using Hapke’s radiative transfer model. Analysis of the spectrum for a minimally disturbed soil indicates that it contains 0.368 wt % SMFe, corresponding to an Is/FeO maturity index of ~53 and indicating that the landing site is submature. The soil at a location that was more disturbed contains 0.217 wt % SMFe, suggesting that the material removed by the rocket blast is more weathered than the regolith that remained behind. We conclude that maturity differences related to removal of the finest, highly mature particles play a major role in the observed reflectance changes associated with rocket blast.…This research was supported by the National High Technology Research and Development Program of China (863
Program: 2015AA123704), the National Natural Science Foundation of China (41422110 and 41490633), the Science
and Technology Development Fund of Macau (020/2014/A1), and Minor Planet Foundation of Purple Mountain Observatory. The contribution of D.T.B. was made possible by the Chinese Academy of Sciences President’s International Fellowship Initiative, grant 2015VEB057 and by NASA Lunar Data Analysis Program grant NNX16AN55G. E.A.C. thanks NSERC and the Canadian Space Agency for supporting this study.https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL07265
Acid weathering of basalt and basaltic glass: 2. Effects of microscopic alteration textures on spectral properties
Get PDFAcid alteration has long been proposed for the Martian surface, and so it is important to understand how the resulting alteration textures affect surface spectra. Two basaltic materials of varying crystallinity were altered in two different H2SO4 solutions (pH 1 and pH 3) for 220 days. The unaltered and altered samples were studied in the visible and near infrared (VNIR) and thermal infrared (TIR), and select samples were chosen for scanning electron microscopy analysis. Materials altered in pH 3 solutions showed little to no physical alteration, and their spectral signatures changed very little. In contrast, all materials altered in pH 1 acid displayed silica-rich alteration textures, and the morphology differed based on starting material crystallinity. The more crystalline material displayed extensive alteration reaching into the sample interiors and had weaker silica spectral features. The glass sample developed alteration layers tens of microns thick, exhibiting amorphous silica-rich spectral features that completely obscured the substrate. Thus, the strong absorption coefficient of silica effectively decreases the penetration depth of TIR spectral measurements, causing silica abundances to be grossly overestimated in remote sensing data. Additionally, glass samples with silica layers exhibited distinct concave up blue spectral slopes in the VNIR. Spectra from the northern lowland plains of Mars are modeled with high abundances of amorphous silica and exhibit concave up blue spectral slopes and are thus consistent with acid altered basaltic glass. Therefore, we conclude that large regions of the Martian surface may have formed through the interaction of basaltic glass with strongly acidic fluids.This work was funded in part by the NASA 2001 Mars Odyssey THEMIS project (Jet Propulsion Laboratory contract 1228404 through Arizona State University) and by the Arizona State University Exploration Postdoctoral Fellowship. …the Natural Sciences and Engineering Research Council of Canada, the Canadian Space Agency, the Canada Foundation for Innovation, the Manitoba Research Innovations Fund, and the University of Winnipeg for supporting the establishment and operation of the Planetary Spectrophotometer Facility.https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016JE00511
Isotopic reconstruction of the weaning process in the archaeological population of Canímar Abajo, Cuba: A Bayesian probabilities mixing models approach
Get PDFThe general lack of well-preserved juvenile skeletal remains from Caribbean archaeological sites has, in the past, prevented evaluations of juvenile dietary changes. Canímar Abajo (Cuba), with a large number of well-preserved juvenile and adult skeletal remains, provided a unique opportunity to fully assess juvenile paleodiets from an ancient Caribbean population. Ages for the start and the end of weaning and possible food sources used for weaning were inferred by combining the results of two Bayesian probability models that help to reduce some of the uncertainties inherent to bone collagen isotope based paleodiet reconstructions. Bone collagen (31 juveniles, 18 adult females) was used for carbon and nitrogen isotope analyses. The isotope results were assessed using two Bayesian probability models: Weaning Ages Reconstruction with Nitrogen isotopes and Stable Isotope Analyses in R. Breast milk seems to have been the most important protein source until two years of age with some supplementary food such as tropical fruits and root cultigens likely introduced earlier. After two, juvenile diets were likely continuously supplemented by starch rich foods such as root cultigens and legumes. By the age of three, the model results suggest that the weaning process was completed. Additional indications suggest that animal marine/riverine protein and maize, while part of the Canímar Abajo female diets, were likely not used to supplement juvenile diets. The combined use of both models here provided a more complete assessment of the weaning process for an ancient Caribbean population, indicating not only the start and end ages of weaning but also the relative importance of different food sources for different age juveniles.The research was funded under a Social Sciences and Humanities Research Council of Canada standard Research Grant, SSHRCÐ410-2011-1179 (http://www.sshrc-crsh.gc.ca/home-accueil-eng.aspx), Social Sciences and Humanities Research Council of Canada postdoctoralhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.017606
Chill out: physiological responses to winter ice-angling in two temperate freshwater fishes
Get PDFA large body of research has documented the stress response of fish following angling capture. Nearly all of these studies have taken place during the open-water season, with almost no work focused on the effects of capture in the winter via ice angling. We therefore conducted a study to examine physiological disturbance and reflex impairment following capture by ice-angling in two commonly targeted species, bluegill Lepomis macrochirus and yellow perch Perca flavescens. Fish were captured from a lake in eastern Wisconsin (USA) and sampled either immediately or after being held in tanks for 0.5, 2 or 4 h. Sampling involved the assessment of reflex action mortality predictors (RAMP) and a blood biopsy that was used to measure concentrations of plasma cortisol and lactate. The capture-induced increase in plasma cortisol concentration was delayed relative to responses documented in previous experiments conducted in the summer and reached a relative high point at 4 h post-capture. Reflex impairment was highest at the first post-capture time point (0.5 h) and declined with each successive sampling (2 and 4 h) during recovery. Bluegill showed a higher magnitude stress response than yellow perch in terms of plasma cortisol and RAMP scores, but not when comparing plasma lactate. Overall, these data show that ice-angling induces a comparatively mild stress response relative to that found in previous studies of angled fish. While recovery of plasma stress indicators does not occur within 4 h, declining RAMP scores demonstrate that ice-angled bluegill and yellow perch do recover vitality following capture."This work was supported by Federal Aid in Sport Fish Restoration Project F-69-R-29 to J.A.S."https://academic.oup.com/conphys/article/5/1/cox027/376958
Oral History and Impostors: What To Do
No full texthttps://oralhistorycentre.ca/2017/08/11/oral-history-and-impostors-what-to-do
Final Report
Get PDFThis is the Final Report of the project, ‘Advancing Coordination of the Winnipeg Homeless Sector’. Over the last year, there have been efforts in the homeless serving community to map out service gaps and needs, and to discuss HPS funding and how it aligns with community priorities. The current project advances these efforts to integrate more community knowledge, planning, and engagement into the Homelessness Partnering Strategy (HPS) funding process
A Special Report on Demographic and Housing Market Factors in Winnipeg’s Downtown
Get PDFThe Winnipeg Downtown Profile carries out an analysis of demographic and housing market factors that may influence the need for incentives in the downtown Winnipeg housing market. This report informs CentreVenture’s proposed “ 10 Year Housing Evaluation” and helps to address the proposed question, “ What price do new downtown housing projects need to achieve to encourage more people to move downtown?
Strategies for Meaningful Engagement between Community-Based Health Researchers and First Nations Participants
Get PDFThe Baby Teeth Talk Study (BTT) is a partnership-based research project looking at interventions to prevent early childhood caries (ECC) in First Nations populations in Canada. Community-based researchers (CBRs) conducted preventive and behavioral interventions that targeted expectant mothers and their newborns, over a 3-year period. The work of the CBRs requires a great deal of training and skills to administer the interventions. It also requires a broad set of strategies to meaningfully engage participants to make health-promoting changes in their behavior to prevent ECC in their children. After implementing the intervention, BTT CBRs participated in interviews to explore the strategies they employed to engage participants in the prevention of ECC. CBRs perceived two key strategies as essential for meaningful engagement with BTT participants. First, CBRs indicated that their shared experiences through motherhood, First Nations identity, age, and childhood experience provided a positive foundation for dialog with participants that lead to build trust and rapport. Second, supportive interpersonal and culturally based communication skills of the CBR provided further foundation to engage with participants from a strength-based approach. For example, the CBRs knew how to effectively communicate in ways such as being gentle, non-intrusive, and avoiding any perception of judgment when discussing oral health behavior. In First Nations health research, CBRs can provide an essential link in engaging participants and the community for improvements in health. Researchers should carefully consider characteristics such as shared experience and ability to understand cultural communication styles when hiring CBRs in order to build a solid foundation of trust with research participants."The Baby Teeth Talk Study (Canada) is funded by the Canadian Institutes of Health Research (CIHR) International Collaborative Indigenous Health Research Partnership (ICIHRP) grant number IDP-103988."https://www.frontiersin.org/articles/10.3389/fpubh.2017.00138/ful