1,721,260 research outputs found
The power of place: climate change as driver of hominin evolution and dispersal over the past five million years
Full text linkKroon, D. [Promotor]Vonhof, H.B. [Copromotor
Planktic foraminiferal response to changing SE Atlantic oceanography
Full text linkKroon, D. [Promotor]Brummer, G.J. [Copromotor]Peeters, F.J.C. [Copromotor
Fluvial and marine sedimentation at a passive continental margin : The late Quaternary Tagus depositional system
Full text linkberghe, J.F. [Promotor]Kroon, D. [Promotor
Lines of Time : Seasonality, climate and environments of the Miocene Pebas Formation in western Amazonia derived from chemical records in molluscan growth-bands
Full text linkHinte, J.E. [Promotor]van Kroon, D. [Promotor]Ganssen, G.M. [Copromotor]Vonhof, H.B. [Copromotor
Orbitally forced climate change in the late mid-Eocene time at Blake Nose (Leg 171B): evidence from stable isotopes in foraminifera
No full textFluctuations in the position of the Proto Gulf Stream: Evidence from high-resolution stable isotope results
No full textThe Gulf Stream is prominent western boundary current in the North Atlantic. However, little is known about the evolution of the Gulf Stream, particularly during times of elevated greenhouse gases and global temperatures. High-resolution (3 k.y.) stable isotope analyses (?18O, ?13C) were conducted on middle Eocene (ca. 40 - 37 Ma) planktonic foraminifera from the western North Atlantic (Ocean Drilling Program Site 1052). The study exposed a more complicated pattern of climate variability than was formerly anticipated, with large (>1 per mil) and rapid (>10 k.y.) variations in ?18O. The magnitude of change is greater than that seen in open-ocean Pleistocene records but could not have been caused by ice-volume and/or sea-level fluctuations. Instead, the oxygen isotope shifts resulted primarily from large oscillations in sea-surface temperatures with shifts of up to 12°C. Climatic modeling results have indicated the presence of a Gulf Stream analogue during the Eocene. The movement of the Gulf Stream would cause sea-surface temperatures to change dramatically over a small area. High frequency instability of sea-surface temperatures may have been attributable to deflections in the position of the Gulf Stream across the Blake Plateau. There is a strong 400 kyr cyclicity evident in the sea-surface temperature record, suggesting that fluctuations in the position of the Gulf Stream were caused by feedbacks within the climate system, in response to orbital changes in solar insolation
., Mid-Eocene deep water, the Late Palaeogene Thermal Maximum and continental slope mass wasting during the CretaceouPalaeogene impact
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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