In calcites and dolomites in seven African carbonatites, SrO, FeO and MnO occur in concentrations from 1 to 2 wt.%, whereas Ce, Y, Cu and Zn occur only at the ppm level. Sr, Ce and Y partition preferentially into calcite relative to co-existing dolomite, whereas Fe and Mn favour dolomite. Sr partitions preferentially into calcite relative to co-exisiting apatite, but the light rare-earth elements partition into apatite. Magnetite from Kerimasi contains up to 13 wt.% MgO and 6 wt.% MnO, extending the known ranges in composition of magnetites from carbonatites.
Optical frequency standards, or lasers stabilized to atomic or molecular transitions, are widely used in length metrology and laser ranging, provide a backbone for optical communications and lie at the heart of next-generation optical atomic clocks. Here we demonstrate a compact, low-power optical frequency reference based on the Doppler-free, two-photon transition in rubidium-87 at 778 nm implemented on a micro-optics breadboard. Our optical reference achieves a fractional frequency instability of 2.9×10−12/
τ
for averaging times τ less than 103 s, has a volume of ≈35 cm3 and operates on ≈450 mW of electrical power. The advanced optical integration presented here demonstrates a key step towards the development of compact optical clocks and the broad dissemination of SI-traceable wavelength references.
In a nuclear war, volcanic eruption, asteroid or comet impact that causes an abrupt sunlight reduction scenario (ASRS), agricultural yields would plummet. Global society is currently unprepared for such an event, implying an urgent need for evaluation and prioritization of solutions. We show effective deployment of resilient food solutions appears sufficient to fulfill global energy and macronutrient food requirements, potentially saving billions from famine. A Monte Carlo analysis of resilient food outcomes, using a linear optimization model, shows a 95% probability of global food availability between 2,100 and 3,500 Kcals per capita per day in a nuclear winter scenario involving 150 Tg of soot in the stratosphere. Our analysis indicates nutritionally sufficient diets from resilient foods would be widely affordable, costing US$1.73 daily, though subsidization could be needed across Southern Asia and Sub-Saharan Africa. Post-disaster conflict or insufficient international cooperation could increase costs and reduce output, hampering effective resilient food deployment.
A new large-volume, high-pressure facility is being utilized and developed
as part of GeoSoilEnviroCARS at a third-generation synchrotron, the
Advanced Photon Source. This user facility consists of two large-volume
presses (LVP), a 2.5 MN (250 ton) LVP installed at the bending magnet
beamline, and a 10 MN (1000 ton) LVP at the insertion device beamline. Here
we report some techniques currently being developed with the 10 MN
LVP and the latest scientific results obtained using the 2.5 MN LVP.
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