Nathaniel A. Lifton

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This article describes two studies based on an integration of theory and research in object relations and developmental social cognition. The following four dimensions were assessed in 2nd and 5th graders and in 9th and 12th graders using Thematic Apperception Test (TAT) responses and Ss' descriptions of meaningful interpersonal episodes: complexity of(More)
Discordant cosmogenic nuclide exposure ages derived from Be, Al, and C extracted from quartz in rocky summits along the eastern rim of the central Baffin Island plateau provide constraints on the efficiency of erosion by the Laurentide Ice Sheet (LIS) and on the timing and duration of ice-free conditions in the eastern Canadian Arctic. In situ C records the(More)
27 Models of the production of cosmogenic nuclides typically incorporate an adjustable production rate parameter that is scaled for variations in production with latitude and altitude. In practice, this production rate parameter is set by calibration of the model using cosmogenic nuclide data from sites with independent age constraints. In this paper, we(More)
The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the(More)
[1] Radiocarbon measurements at ice margin sites and blue ice areas can potentially be used for ice dating, ablation rate estimates and paleoclimatic reconstructions. Part of the measured signal comes from in situ cosmogenic C production in ice, and this component must be well understood before useful information can be extracted from C data. We combine(More)
Constraining the timing of past ice-sheet change is important for assessing the cryospheric expression of climate change and improving our understanding of ice sheet dynamics. Geochronology used to construct past ice-sheet reconstructions, however, can be ineffective in polar environments where ice sheets were polythermal and left varying imprints on(More)
The in situ cosmogenic nuclide C is unique compared with other nuclides because of its short halflife, and when combined with longer-lived isotopes (e.g. Be), in situ C can be a powerful tool for deciphering recent and complex surface exposure histories. Like all in situ cosmogenic nuclides, quantifying earth surface processes with in situ C requires a(More)