Chemical compositions of impact melt breccias and target rocks from the Tenoumer impact crater, MauritaniaAbstract-The impact melt breccias from the Tenoumer crater (consisting of a fine-grained intergrowth of plagioclase laths, pyroxene crystals, oxides, and glass) display a wide range of porosity and contain a large amount of target rock clasts. Analyses of major elements in impact melt rocks show lower contents of SiO 2 , Al 2 O 3 , and Na 2 O, and higher contents of MgO, Fe 2 O 3 , and CaO, than the felsic rocks (i.e., granites and gneisses) of the basement. In comparison with the bulk analyses of the impact melt, the glass is strongly enriched in Si-Al, whereas it is depleted both in Mg and Fe; moreover, the impact melt rocks are variably enriched or depleted in some REE with respect to the felsic and mafic bedrock types. Gold is slightly enriched in the impact melt, and Co, Cr, and Ni abundances are possibly due to a contribution from mafic bedrock.Evidences of silicate-carbonate liquid immiscibility, mainly as spherules and globules of calcite within the silicate glass, have been highlighted.HMX mixing calculation confirm that the impact melt rocks are derived from a mixing of at least six different target lithologies outcropping in the area of the crater. A large contribution is derived from granitoids (50%) and mica schist (17-19%), although amphibolites (∼15%), cherty limestones (∼10%), and ultrabasites (∼6%) components are also present.The very low abundances of PGE in the melt rock seem to come mainly from some ultrabasic target rocks; therefore, the contamination from the meteoritic projectile appears to have been negligible.
Background: Cross-unit handovers transfer responsibility for the patient among healthcare teams in different clinical units, with missed information, potentially placing patients at risk for adverse events. Objectives: We analysed the communications between high-acuity and low-acuity units, their content and social context, and we explored whether common conceptual ground reduced potential threats to patient safety posed by current handover practices. Methods: We monitored the communication of five content items using handover probes for 22 patient transitions of care between high-acuity 'sender units' and low-acuity 'recipient units'. Data were analysed and discussed in focus groups with healthcare professionals to acquire insights into the characteristics of the common conceptual ground. Results: High-acuity and low-acuity units agreed about the presence of alert signs in the discharge form in 40% of the cases. The focus groups identified prehandover practices, particularly for anticipatory guidance that relied extensively on verbal phone interactions that commonly did not involve all members of the healthcare team, particularly nursing. Accessibility of information in the medical records reported by the recipient units was significantly lower than reported by sender units. Common ground to enable interpretation of the complete handover content items existed only among selected members of the healthcare team. Conclusions: The limited common ground reduced the likelihood of correct interpretation of important handover information, which may contribute to adverse events. Collaborative design and use of a shared set of handover content items may assist in creating common ground to enable clinical teams to communicate effectively to help increase the reliability and safety of cross-unit handovers.
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