Late accretionary history of Earth and Moon preserved in lunar impactites.

Late accretion describes the final addition of Earth’s mass following Moon formation and includes a period of Late Heavy Bombardment (LHB), which occurred either as a short-lived cataclysm triggered by a late giant planet orbital instability or a declining bombardment during late accretion. Using genetically characteristic ruthenium and molybdenum isotope compositions of lunar impact–derived rocks, we show that the impactors during the LHB and the entire period of late accretion were the same type of bodies and that they originated in the terrestrial planet region. Because a cataclysmic LHB would have, in part, resulted in compositionally distinct projectiles, we conclude that the LHB reflects the tail end of accretion.

New insights into Mo and Ru isotope variation in the nebula and terrestrial planet accretionary genetics.

When corrected for the effects of cosmic ray exposure, Mo and Ru nucleosynthetic isotope anomalies in iron meteorites from at least nine different parent bodies are strongly correlated in a manner consistent with variable depletion in -process nucleosynthetic components. In contrast to prior studies, the new results show no significant deviations from a single correlation trend. In the refined Mo-Ru cosmic correlation, a distinction between the non-carbonaceous (NC) group and carbonaceous chondrite (CC) group is evident.

The Elusive Standard of Care.

In medical negligence cases, the forensic expert must explain to a trier of fact what a defendant physician should have done, or not done, in a specific set of circumstances and whether the physician's conduct constitutes a breach of duty. The parameters of the duty are delineated by the standard of care. Many facets of the standard of care have been well explored in the literature, but gaps remain in a complete understanding of this concept.

Characterizing cosmochemical materials with genetic affinities to the Earth: Genetic and chronological diversity within the IAB iron meteorite complex.

The IAB iron meteorite complex consists of a main group (MG) and five chemical subgroups (sLL, sLM, sLH, sHL, and sHH). Here, mass-independent Mo and radiogenic 182W isotope compositions are reported for IAB complex meteorites to evaluate the genetics and chronology, respectively, of the MG and subgroups. Osmium isotopes are used to correct for cosmic ray exposure effects on isotopes of Mo andW.

High-precision analysis of W/W and W/W by negative thermal ionization mass spectrometry: Per-integration oxide corrections using measured O/O.

Here we describe a new analytical technique for the high-precision measurement of W/W and W/W using negative thermal ionization mass spectrometry (N-TIMS). We improve on the recently reported method of Trinquier et al. (2016), which described using Faraday cup collectors coupled with amplifiers utilizing 10 Ω resistors to continuously monitor the O/O of WO and make per-integration oxide corrections.