Institution
Purdue University
Education•West Lafayette, Indiana, United States•
About: Purdue University is a education organization based out in West Lafayette, Indiana, United States. It is known for research contribution in the topics: Population & Context (language use). The organization has 73219 authors who have published 163563 publications receiving 5775236 citations. The organization is also known as: Purdue & Purdue-West Lafayette.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this article, the authors report proxy records of sea surface temperatures from multiple ocean localities and show that the high-latitude temperature decrease was substantial and heterogeneous, and that Northern Hemisphere glaciation was not required to accommodate the magnitude of continental ice growth during this time.
Abstract: About 34 million years ago, Earth's climate shifted from a relatively ice-free world to one with glacial conditions on Antarctica characterized by substantial ice sheets. How Earth's temperature changed during this climate transition remains poorly understood, and evidence for Northern Hemisphere polar ice is controversial. Here, we report proxy records of sea surface temperatures from multiple ocean localities and show that the high-latitude temperature decrease was substantial and heterogeneous. High-latitude (45 degrees to 70 degrees in both hemispheres) temperatures before the climate transition were ∼20°C and cooled an average of ∼5°C. Our results, combined with ocean and ice-sheet model simulations and benthic oxygen isotope records, indicate that Northern Hemisphere glaciation was not required to accommodate the magnitude of continental ice growth during this time.
652 citations
••
Utrecht University1, Yale University2, Rice University3, Purdue University4, Alfred Wegener Institute for Polar and Marine Research5, Stockholm University6, University of Rhode Island7, Brown University8, United States Geological Survey9, University of Bordeaux10, Aix-Marseille University11, Centre national de la recherche scientifique12, Yamagata University13, University College London14, Norwegian Polar Institute15, Boston University16, British Geological Survey17, University of Michigan18, Kyushu University19, University of Southampton20, University of Aberdeen21, University of Padua22, Japan Agency for Marine-Earth Science and Technology23, James Madison University24, University of Tsukuba25, Tohoku University26, National Institute of Advanced Industrial Science and Technology27, Hokkaido University28
TL;DR: It is shown that sea surface temperatures near the North Pole increased from ∼18 °C to over 23°C during this event, which suggests that higher-than-modern greenhouse gas concentrations must have operated in conjunction with other feedback mechanisms—perhaps polar stratospheric clouds or hurricane-induced ocean mixing—to amplify early Palaeogene polar temperatures.
Abstract: The Palaeocene/Eocene thermal maximum, ~55 million years ago, was a brief period of widespread, extreme climatic warming1, 2, 3, that was associated with massive atmospheric greenhouse gas input4. Although aspects of the resulting environmental changes are well documented at low latitudes, no data were available to quantify simultaneous changes in the Arctic region. Here we identify the Palaeocene/Eocene thermal maximum in a marine sedimentary sequence obtained during the Arctic Coring Expedition5. We show that sea surface temperatures near the North Pole increased from ~18 °C to over 23 °C during this event. Such warm values imply the absence of ice and thus exclude the influence of ice-albedo feedbacks on this Arctic warming. At the same time, sea level rose while anoxic and euxinic conditions developed in the ocean's bottom waters and photic zone, respectively. Increasing temperature and sea level match expectations based on palaeoclimate model simulations6, but the absolute polar temperatures that we derive before, during and after the event are more than 10 °C warmer than those model-predicted. This suggests that higher-than-modern greenhouse gas concentrations must have operated in conjunction with other feedback mechanisms—perhaps polar stratospheric clouds7 or hurricane-induced ocean mixing8—to amplify early Palaeogene polar temperatures.
652 citations
••
TL;DR: A feature model of immediate memory is presented, and the model is shown to account for the major modality-based phenomena of the immediate serial recall literature, including modalities-based temporal grouping effects and the negative effects of phonological similarity.
Abstract: A feature model of immediate memory is presented, and simulations are described. List items are characterized as multiattribute vectors that can be selectively overwritten by subsequent external events and by the ongoing stream of internal activity. Degraded primary memory vectors are compared with intact secondary memory vectors, and retrieval likelihood is computed as the ratio of similarities. The model is shown to account for the major modality-based phenomena of the immediate serial recall literature, including modality-based temporal grouping effects and the negative effects of phonological similarity.
650 citations
••
TL;DR: In this article, an ensemble-averaged statistics at constant phase of the turbulent near-wake flow (Reynolds number ≈ 21400 around a square cylinder) were obtained from two-component laser-Doppler measurements.
Abstract: Ensemble-averaged statistics at constant phase of the turbulent near-wake flow (Reynolds number ≈ 21400 around a square cylinder have been obtained from two-component laser-Doppler measurements. Phase was defined with reference to a signal taken from a pressure sensor located at the midpoint of a cylinder sidewall. The distinction is drawn between the near wake where the shed vortices are ‘mature’ and distinct and a base region where the vortices grow to maturity and are then shed. Differences in length and velocity scales and vortex celerities between the flow around a square cylinder and the more frequently studied flow around a circular cylinder are discussed. Scaling arguments based on the circulation discharged into the near wake are proposed to explain the differences. The relationship between flow topology and turbulence is also considered with vorticity saddles and streamline saddles being distinguished. While general agreement with previous studies of flow around a circular cylinder is found with regard to essential flow features in the near wake, some previously overlooked details are highlighted, e.g. the possibility of high Reynolds shear stresses in regions of peak vorticity, or asymmetries near the streamline saddle. The base region is examined in more detail than in previous studies, and vorticity saddles, zero-vorticity points, and streamline saddles are observed to differ in importance at different stages of the shedding process.
649 citations
Authors
Showing all 73693 results
Name | H-index | Papers | Citations |
---|---|---|---|
Yi Cui | 220 | 1015 | 199725 |
Yi Chen | 217 | 4342 | 293080 |
David Miller | 203 | 2573 | 204840 |
Hongjie Dai | 197 | 570 | 182579 |
Chris Sander | 178 | 713 | 233287 |
Richard A. Gibbs | 172 | 889 | 249708 |
Richard H. Friend | 169 | 1182 | 140032 |
Charles M. Lieber | 165 | 521 | 132811 |
Jian-Kang Zhu | 161 | 550 | 105551 |
David W. Johnson | 160 | 2714 | 140778 |
Robert Stone | 160 | 1756 | 167901 |
Tobin J. Marks | 159 | 1621 | 111604 |
Joseph Wang | 158 | 1282 | 98799 |
Ed Diener | 153 | 401 | 186491 |
Wei Zheng | 151 | 1929 | 120209 |