Publications by authors named "L Porritt"

F-based acoustic measures were extracted from a brief, sentence-final target word spoken during structured play interactions between mothers and their 3- to 14-month-old infants, and were analyzed based on demographic variables and DSM-IV Axis-I clinical diagnoses and their common modifiers. F range (ΔF) was negatively correlated with infant age and number of children. ΔF was significantly smaller in clinically depressed mothers and mothers diagnosed with depression in partial remission, relative to non-depressed mothers, mothers diagnosed with depression in full remission, and those diagnosed with depressive disorder not otherwise specified.

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Kimberlite volcanism involves the emplacement of olivine-rich volcaniclastic deposits into volcanic vents or pipes. Kimberlite deposits are typically pervasively serpentinised as a result of the reaction of olivine and water within a temperature range of 130-400 °C or less. We present a model for the influx of ground water into hot kimberlite deposits coupled with progressive cooling and serpentisation.

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Volcanoes are increasingly recognized as agents and recorders of global climate variability, although deciphering the linkages between planetary climate and volcanism is still in its infancy. The growth and emergence of subaqueous volcanoes produce passage zones, which are stratigraphic surfaces marking major transitions in depositional environments. In glaciovolcanic settings, they record the elevations of syn-eruptive englacial lakes.

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Kimberlite magmas have the deepest origin of all terrestrial magmas and are exclusively associated with cratons. During ascent, they travel through about 150 kilometres of cratonic mantle lithosphere and entrain seemingly prohibitive loads (more than 25 per cent by volume) of mantle-derived xenoliths and xenocrysts (including diamond). Kimberlite magmas also reputedly have higher ascent rates than other xenolith-bearing magmas.

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