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Strain localization is central to the transition between continental rifting and seafloor spreading. In the East African Rift System (EARS), there is an emerging understanding of the link between extensional pulses and magmatic episodes. We investigate modern magmatism located within the Turkana Depression and its relationship with the distribution of extensional strain. We probe the source of magmatism at South Island volcano using bulk rock, melt inclusion and olivine geochemical data and find that the magmas are derived from sub-lithospheric sources equivalent to magmatism in the more mature sectors of the rift. The depth extent of the magmatic plumbing system of South Island is constrained using vapour saturation pressures derived from bubble-corrected H2O and CO2 concentrations in melt inclusions and the results indicate a magmatic system resembling modern axial volcanic systems observed in other parts of the EARS. The zone of focused axial magmatism that South Island represents has evolved contemporaneously with a region of focused axial faulting that has accommodated the majority of regional Holocene extension and subsidence at this latitude. We conclude that at South Island there has been a migration of magmatic and tectonic strain towards the modern zone of focused intrusion along this portion of the EARS. Supplementary material: S1–S2 image files, data table files S3–S6 and caption file S7 are available at https://doi.org/10.6084/m9.figshare.c.6026627 [ABSTRACT FROM AUTHOR]

The initial interaction between material rising from the African Large Low Shear Velocity Province and the African lithosphere manifests as the Eocene continental large igneous province (LIP), centred on southern Ethiopia and northern Kenya. Here we present a geographically well-distributed geochemical dataset comprising flood basalt lavas of the Eocene continental LIP to refine the regional volcano-stratigraphy into three distinct magmatic units: (1) the highly alkaline small-volume Akobo Basalt (49.4–46.6 Ma), representing the initial phase of flood basalt volcanism derived from the melting of lithospheric–mantle metasomes; (2) the primitive and spatially restricted Amaro Basalt (45.2–39.8 Ma), representing the early main phase of flood basalt volcanism derived from the melting of the upwelling thermochemical anomaly; and (3) the spatially extensive Gamo–Makonnen magmatic unit (38–28 Ma), representing the mature main phase of flood basalt volcanism that has undergone significant processing within the lithosphere and resulted in relatively homogeneous compositions. The focused intrusion of these main phase magmas over 10 myr preconditioned the African lithosphere for the localization of strain during subsequent episodes of lithospheric stretching. The focusing of strain into the region occupied by this continental LIP may have contributed to the initial extension in SW Ethiopia that is associated with the East African Rift.

Abstract: Background: This study aimed to quantify the clinical parameters of mono- and bipolar instruments that inhibit pacemaker function. The specific aims were to quantify pacer inhibition resulting from the monopolar instrument by altering the generator power setting, the generator mode, the distance between the active electrode and the pacemaker, and the location of the dispersive electrode. Methods: A transvenous ventricular lead pacemaker overdrive paced the native heart rate of an anesthetized pig. The primary outcome variable was pacer inhibition quantified as the number of beats dropped by the pacemaker during 5 s of monopolar active electrode activation. Results: Lowering the generator power setting from 60 to 30 W decreased the number of dropped paced events (2.3 ± 1.2 vs 1.6 ± 0.8 beats; p = 0.045). At 30 W of power, use of the cut mode decreased the number of dropped paced beats compared with the coagulation mode (0.6 ± 0.5 vs 1.6 ± 0.8; p = 0.015). At 30 W coagulation, firing the active electrode at different distances from the pacemaker generator (3.75, 7.5, 15, and 30 cm) did not change the number of dropped paced beats (p = 0.314, analysis of variance [ANOVA]). The dispersive electrode was placed in four locations (right/left gluteus, right/left shoulder). More paced beats were dropped when the current vector traveled through the pacemaker/leads than when it did not (1.5 ± 1.0 vs 0.2 ± 0.4; p < 0.001). Conclusions: Clinical parameters that reduce the inhibition of a pacemaker by monopolar instruments include lowering the generator power setting, using cut (vs coagulation) mode, and locating the dispersive electrode so the current vector does not traverse the pacemaker generator or leads.

In order to understand possible future scenarios of intracaldera volcanism at Yellowstone, we provide new insights on the generation and eruption of the youngest intracaldera rhyolitic magmas using quartz petrography, geochemistry, and geobarometry. We propose that magma ascent occurred rapidly from the source regions at 8-10 km to the surface along major regional faults, without storage at shallower depths. These source regions coincide with the upper parts of the present-day imaged magma chamber, while the faults focus much of the present-day caldera unrest. Based on these combined observations, we propose that volcanism has a higher probability to resume in three fault-controlled NNW-trending lineaments, the first coinciding with the western caldera rim, the second lying across the central region of the caldera, and the third extending across the northeastern caldera. The first two lineaments focused recent intracaldera volcanism (174-70 ka), while the latter is the most active in terms of current caldera unrest. Future volcanism could include large-volume lava flows and phreatomagmatic rhyolitic eruptions. The identification of these three regions together with potentially rapid eruptive mechanisms may help to better define future monitoring efforts necessary to improve eruption forecasting in this vast area of volcanic unrest. [ABSTRACT FROM AUTHOR]

Producing low-dross ingots has been a long-term goal in aluminium cast houses. The patented CASTfill technology [1] is a low-dross and high-productivity pouring system developed to fulfil this demand. This paper describes the research methods used during the development of CASTfill; now in service at Boyne Smelters Limited (BSL) since August 2009. The importance of combining scientific modelling and testing procedures with process operability, maintainability and durability to ensure the success of new technology in a production facility is also highlighted. Ingot assessments showed that the latest CASTfill design greatly reduced dross generated during mould filling. Improved ingot packaging and reduced variation of ingot weights were also observed as the results of a more tranquil flow of molten aluminium through CASTfill and its uniquely modular design.

Achieving in-specification melt analysis first time has been the Holy Grail of many cast houses for a number of years and for a good reason. For many producers, the furnaces are the bottleneck of the value added casting process and removing that hurdle means big dollars. A six sigma project was carried out at the Bell Bay smelter aimed at reducing the time it takes to bring a furnace within chemical specification and highlighted that “in-spec first time” is more achievable than many think. This paper covers the steps having an impact on alloy recovery and suggests a “best practice” to be followed in each area. As is shown, consistently following these guidelines through robust controls can generate a significant increase in throughput of value add facilities in your cast house.

Scrap rate, throughput, alloy recovery and raw materials are all areas of the casthouse which usually get substantial attention as means of either increasing profits or reducing costs. However, furnaces, which are often overlooked by the casthouse, can also deliver surprisingly high savings. Moreover, these potential savings can only magnify as energy costs and pressures to reduce carbon footprint increase. This paper gives an insight into where savings can be achieved by a casthouse with proper furnace operation. Knowledge of how a furnace should be operated is often neglected but as this paper tries to highlight, developing this knowledge can be extremely worthwhile.

The surface ablation threshold fluence of fused silica and two porcine cornea layers, the epithelium and the stroma, is characterized as a function of the laser pulse duration in the range of 100 fs-5 ps for a wavelength of 800 nm (Ti:sapphire laser system). The plateaulike region observed between 100 fs and 1 ps for the corneal layers indicates that for use in laser surgery, laser pulse durations chosen within this range should be practically equivalent. Our model predicts that the ablation threshold will decrease rapidly for pulse durations in the low end of the femtosecond regime.