http://dspace.lafayette.edu:8080 The Lafayette Digital Repository captures, stores, indexes, preserves, and distributes digital research material. http://hdl.handle.net/10385/542 Evolution of the eastern tropical Pacific through Plio-Pleistocene glaciation Lawrence, Kira T. Liu, Z.H. Herbert, T.D. A tropical Pacific climate state resembling that of a permanent El Nino is hypothesized to have ended as a result of a reorganization of the ocean heat budget similar to 3 million years ago, a time when large ice sheets appeared in the high latitudes of the Northern Hemisphere. We report a high-resolution alkenone reconstruction of conditions in the heart of the eastern equatorial Pacific (EEP) cold tongue that reflects the combined influences of changes in the equatorial thermocline, the properties of the thermocline's source waters, atmospheric greenhouse gas content, and orbital variations on sea surface temperature (SST) and biological productivity over the past 5 million years. Our data indicate that the intensification of Northern Hemisphere glaciation similar to 3 million years ago did not interrupt an almost monotonic cooling of the EEP during the Plio-Pleistocene. SST and productivity in the eastern tropical Pacific varied in phase with global ice volume changes at a dominant 41,000-year (obliquity) frequency throughout this time. Changes in the Southern Hemisphere most likely modulated most of the changes observed. Fri, 07 Apr 2006 00:00:00 GMT http://hdl.handle.net/10385/541 High-amplitude variations in North Atlantic sea surface temperature during the early Pliocene warm period Brown, C.M. Raymo, M.E. Haywood, A.M. Lawrence, Kira T. Herbert, T.D. We provide the first continuous, orbital-resolution sea surface temperature (SST) record from the high-latitude North Atlantic, a region critical to understanding the origin of the Plio-Pleistocene ice ages and proximal to regions that became frequently glaciated after similar to 2.7 Ma. We analyzed sediments from Ocean Drilling Program Site 982 over the last 4 Ma for their alkenone unsaturation index and compared this surface water signal to a benthic delta O-18 record obtained from the same section. We find that while ocean surface temperatures were significantly warmer (similar to 6 degrees C) than modern temperatures during the early Pliocene, they were also as variable as those during the late Pleistocene, a surprising result in light of the subdued variance of oxygen isotopic time series during the interval of 3-5 Ma. We propose two possible explanations for the high orbital-scale SST variability observed: either that a strong, high-latitude feedback mechanism not involving large continental ice sheets alternately cooled and warmed a broad region of the northern high latitudes or that by virtue of its location near the northern margin of the North Atlantic Drift, the site was unusually sensitive to obliquity-driven climate shifts. On supraorbital time scales, a strong, sustained cooling of North Atlantic SSTs (similar to 4.5 degrees C) occurred from 3.5 to 2.5 Ma and was followed by an interval of more modest cooling (an additional 1.5 degrees C) from 2.5 Ma to the present. Evolutionary orbital-scale phase relationships between North Atlantic SST and benthic delta O-18 show that SST began to lead delta O-18 significantly coincident with the onset of strong cooling at Site 982 (similar to 3.5 Ma). We speculate that these changes were related to the growth and subsequent persistence of a Greenland ice sheet of approximately modern size through interglacial states. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/10385/537 Developing Interfaces and Interactivity for DSpace with Manakin (Smith College, June 3, 2009) Luhrs, Eric Mon, 15 Jun 2009 15:42:54 GMT http://hdl.handle.net/10385/534 Emotional intensity predicts autobiographical memory experience Rubin, D. C. LaBar, K. S. Talarico, Jennifer M. College students generated autobiographical memories from distinct emotional categories that varied in valence (positive vs. negative) and intensity (high vs. low). They then rated various perceptual, cognitive, and emotional properties for each memory. The distribution of these emotional memories favored a vector model over a circumplex model. For memories of all specific emotions, intensity accounted for significantly more variance in autobiographical memory characteristics than did valence or age of the memory. In two additional experiments, we examined multiple memories of emotions of high intensity and positive or negative valence and of positive valence and high or low intensity. Intensity was a more consistent predictor of autobiographical memory properties than was valence or the age of the memory in these experiments as well. The general effects of emotion on autobiographical memory properties are due primarily to intensity differences in emotional experience, not to benefits or detriments associated with a specific valence. Fri, 01 Oct 2004 00:00:00 GMT http://hdl.handle.net/10385/533 Confidence, not consistency, characterizes flashbulb memories Rubin, D. C. Talarico, Jennifer M. On September 12, 2001, 54 Duke students recorded their memory of first hearing about the terrorist attacks of September 11 and of a recent everyday event. They were tested again either 1, 6, or 32 weeks later. Consistency for the flashbulb and everyday memories did not differ, in both cases declining over time. However, ratings of vividness, recollection, and belief in the accuracy of memory declined only for everyday memories. Initial visceral emotion ratings correlated with later belief in accuracy, but not consistency, for flashbulb memories. Initial visceral emotion ratings predicted later posttraumatic stress disorder symptoms. Flashbulb memories are not special in their accuracy, as previously claimed, but only in their perceived accuracy. Mon, 01 Sep 2003 00:00:00 GMT