3,758 research outputs found

    Redetermination of conichalcite, CaCu(AsO4)(OH)

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    The crystal structure of conichalcite [calcium copper(II) arsenate(V) hydroxide], with ideal formula CaCu(AsO4)(OH), was redetermined from a natural twinned specimen found in the Maria Catalina mine (Chile). In contrast to the previous refinement from photographic data [Qurashi & Barnes (1963 ▶). Can. Mineral. 7, 561–577], all atoms were refined with anisotropic displacement parameters and with the H atom located. Conichalcite belongs to the adelite mineral group. The Jahn–Teller-distorted [CuO6] octa­hedra share edges, forming chains running parallel to [010]. These chains are cross-linked by eight-coordinate Ca atoms and by sharing vertices with isolated AsO4 tetra­hedra. Of five calcium arsenate minerals in the adelite group, the [MO6] (M = Cu, Zn, Co, Ni and Mg) octa­hedron in conichalcite is the most distorted, and the donor–acceptor O—H⋯O distance is the shortest

    Mineralogy of Vera Rubin Ridge in Gale Crater from the Mars Science Laboratory CheMin instrument

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    Gale crater was selected as the landing site for the Mars Science Laboratory Curiosity rover because of orbital evidence for a variety of secondary minerals in the lower slopes of Aeolis Mons (aka Mount Sharp) that indicate changes in aqueous conditions over time. Distinct units demonstrate orbital spectral signatures of hematite, phyllosilicate (smectite), and sulfate minerals, which suggest that ancient aqueous environments in Gale crater varied in oxidation potential, pH, and water activity. Vera Rubin ridge (VRR) is the first of these units identified from orbit to have been studied by Curiosity. Orbital near-infrared data from VRR show a strong band at 860 nm indicative of hematite. Before Curiosity arrived at VRR, the hypotheses to explain the formation of hematite included (1) precipitation at a redox interface where aqueous Fe2+ was oxidized to Fe3+, and (2) acidic alteration of olivine in oxic fluids. Studying the composition and sedimentology of the rocks on VRR allow us to test and refine these hypotheses and flesh out the depositional and diagenetic history of the ridge. Here, we focus on the mineralogical results of four rock powders drilled from and immediately below VRR as determined by CheMin

    Post‑fledging movement and spatial ecology of the endangered Cape Vulture (\u3ci\u3eGyps coprotheres\u3c/i\u3e)

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    The post-fledging dependence period (PFDP) is one of the most critical stages in the life history of some avian species. Birds are particularly sensitive to mortality during this stage as they must learn essential skills, such as efficient locomotion, proficient food location and predator avoidance. Knowledge of the PFDP would provide valuable information for conservation management of endangered species, many of which experience high juvenile fatality rates. Post-fledging movements of five endangered Cape Vultures were recorded using Global Positioning System/Global System for Mobile communication telemetry in South Africa. Home range sizes, distances travelled from the nest and habitat use were determined over 11 months during the PFDP. Fledglings increased their home range progressively for the first 2 months, then exhibited a rapid increase in home range size associated with dispersal from their natal colony. Maximum net daily distance also rapidly increased following the dispersal period. A preference for protected areas and woody vegetation (representing cliff faces used for roosting) in terms of habitat use for foraging was evident. The knowledge of the movement and habitat use of juvenile Cape Vultures can aid in the effective conservation planning for the species. Conservation programs in identified areas can be focused on power line and wind-farm mitigation, areas of supplementary feeding and anti-poisoning events

    Poor school attendance and exclusion: A systematic review protocol on educational risk factors for self-harm and suicidal behaviours

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    This is the final version. Available from BMJ Publishing Group via the DOI in this record.Introduction Schools have an important role in recognising and preventing self-harm and suicidal behaviour in their students, however little is known about which educational factors are associated with heightened risk We will systematically review the existing evidence on two key educational performance indicators that are routinely collected by school administrative systems: School attendance and exclusion We will investigate their association with self-harm and suicidal behaviour in school-age children and adolescents Knowledge of this association could help inform suicide prevention strategies at clinical, school and population levels Methods and analysis We will conduct a systematic search of Medline, EMBASE, PsycINFO, British Education Index and Education Resources Information Centre (ERIC) from 1 January 1990, and conduct a manual search for additional references We aim to identify studies that explore the association between poor school attendance or exclusion and self-harm or suicidal behaviours in school-age children and adolescents Two independent reviewers will screen titles, abstracts and full-text documents and independently extract relevant data for analysis Study quality will be assessed using a modified Newcastle-Ottawa Scale A descriptive analysis will be performed, and where appropriate, results will be combined in meta-analyses Ethics and dissemination This is a systematic review of published literature, and therefore ethical approval will not be sought We will publish reports in health and education journals, present our work at conferences focused on school mental health and communicate our findings to practitioners and managers in public health, education and child mental health.Wellcome TrustMedical Research Council (MRC)National Institute of Health Research (NIHR

    Educational attainment trajectories among children and adolescents with depression, and the role of sociodemographic characteristics: longitudinal data-linkage study

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    Background Depression is associated with lower educational attainment, but there has been little investigation of long-term educational trajectories in large cohorts with diagnosed depression. Aims: To describe the educational attainment trajectories of children with a depression diagnosis in secondary care, and to investigate whether these trajectories vary by sociodemographic characteristics. / Method: We identified new referrals to South London and Maudsley's NHS Foundation Trust between 2007 and 2013 who received a depression diagnosis at under 18 years old. Linking their health records to the National Pupil Database, we standardised their performance on three assessments (typically undertaken at ages 6–7 years (school Year 2), 10–11 (Year 6) and 15–16 (Year 11)) relative to the local reference population in each academic year. We used mixed models for repeated measures to estimate attainment trajectories. / Results: In our sample of 1492 children, the median age at depression diagnosis was 15 years (interquartile range = 14–16). Their attainment showed a decline between school Years 6 and 11. Attainment was consistently lower among males and those eligible for free school meals. Black ethnic groups also showed lower attainment than White ethnic groups between Years 2 and 6, but showed a less pronounced drop in attainment at Year 11. / Conclusions: Those who receive a depression diagnosis during their school career show a drop in attainment in Year 11. Although this pattern was seen among multiple sociodemographic groups, gender, ethnicity and socioeconomic status predict more vulnerable subgroups within this clinical population who might benefit from additional educational support or more intensive treatment

    Glen Torridon Mineralogy and the Sedimentary History of the Clay Mineral Bearing Unit

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    Clay minerals are common in ancient terrains on Mars and their presence at the surface alludes to aqueous processes in the Noachian to Early Hesperian (>3.5 Ga). Gale crater was selected as Curiositys landing site largely because of the identification of clay mineral rich strata from orbit. On Earth, the types of clay minerals (i.e., smectites) identified in Gale crater are typically juvenile weathering products that ultimately record the interaction between primary igneous minerals with the hydrosphere, atmosphere, and biosphere. Trioctahedral and dioctahedral smectite were identified by Curiosity in units stratigraphically below the Clay Mineral-Bearing Unit (CBU) identified from orbit. Compositional and sedimentological data suggest the smectite formed via authigenesis in a lake environment and may have been altered during early diagenesis. The CBU is stratigraphically equivalent to a hematite-rich unit to the north and stratigraphically underlies sulfate-rich units to the south, suggesting a dynamic environment and evolving history of water in the ancient Gale crater lake. Targeting these clay mineral rich areas on Mars with rover missions provides an opportunity to explore the aqueous and sedimentary history of the planet

    Data Sharing in Astrobiology: The Astrobiology Habitable Environments Database (AHED)

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    Astrobiology is a multidisciplinary area of scientific research focused on studying the origins of life on Earth and the conditions under which life might have emerged elsewhere in the universe. NASA uses the results of Astrobiology research to help define targets for future missions that are searching for life elsewhere in the universe. The understanding of complex questions in Astrobiology requires integration and analysis of data spanning a range of disciplines including biology, chemistry, geology, astronomy and planetary science. However, the lack of a centralized repository makes it difficult for Astrobiology teams to share data and benefit from resultant synergies. Moreover, in recent years, federal agencies are requiring that results of any federally funded scientific research must be available and useful for the public and the science community. The Astrobiology Habitable Environments Database (AHED), developed with a consolidated group of astrobiologists from different active research teams at NASA Ames Research Center, is designed to help to address these issues. AHED is a central, high-quality, long-term data repository for mineralogical, textural, morphological, inorganic and organic chemical, isotopic and other information pertinent to the advancement of the field of Astrobiology
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