High-resolution 14C dating of a 25,000-year lake-sediment record from equatorial East Africa

We dated a continuous, ~22-m long sediment sequence from Lake Challa (Mt. Kilimanjaro area, Kenya/Tanzania) to produce a solid chronological framework for multi-proxy reconstructions of climate and environmental change in equatorial East Africa over the past 25,000 years. The age model is based on a total of 168 AMS 14C dates on bulk-organic matter, combined with a 210Pb chronology for recent sediments and corrected for a variable old-carbon age offset. This offset was estimated by i) pairing bulk-organic 14C dates with either 210Pb-derived time markers or 14C dates on grass charcoal, and ii) wiggle-matching high-density series of bulk-organic 14C dates. Variation in the old-carbon age offset through time is relatively modest, ranging from ~450 yr during glacial and late glacial time to ~200 yr during the early and mid-Holocene, and increasing again to ~250 yr today. The screened and corrected 14C dates were calibrated sequentially, statistically constrained by their stratigraphical order. As a result their constrained calendar-age distributions are much narrower, and the calibrated dates more precise, than if each 14C date had been calibrated on its own. The smooth-spline age-depth model has 95% age uncertainty ranges of ~50–230 yr during the Holocene and ~250–550 yr in the glacial section of the record. The d13C values of paired bulk-organic and grass-charcoal samples, and additional 14C dating on selected turbidite horizons, indicates that the old-carbon age offset in Lake Challa is caused by a variable contribution of old terrestrial organic matter eroded from soils, and controlled mainly by changes in vegetation cover within the crater basin.

Bay Area Women in Creative Music

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Music for Sleeping & Waking Minds

Music for Sleeping & Waking Minds is a 8-hour composition intended for overnight listening. It features 4 performers who wear custom-designed EEG sensors. The performers rest and fall asleep as they naturally would. Over the course of one night, their brainwave activity generates a spatial audio environment. Audiences are invited to sleep or listen as they wish. Composition & concept by Gascia Ouzounian. Physiological interface and interaction design by R. Benjamin Knapp. Audio interface and interaction design by Eric Lyon.

Vaughan Williams and contemporary music: composers' forum

Like many long-lived composers, Vaughan Williams suffered a decline in his reputation immediately following his death, as the emergence in the 1960s of a younger generation of composers rendered much of his work outmoded in the eyes of many critics. In recent years, however, the reception of Vaughan Williams's music among composers has improved markedly, a combination of the ebbing of the tide of high modernism and greater pluralism in contemporary music, and a growing awareness that Vaughan Williams was perhaps more modernist (or at least progressive) than had previously been thought. In interviews with four leading British composers (two of whom were part of the 1960s generation mentioned above), I investigate the nature and extent of Vaughan Williams's legacy to his successors, both musical and social. What emerges is a near consensus on Vaughan Williams's greatest works, but a diversity of views on his compositional techniques and on his place among his European contemporaries.