The correlation of continental sedimentary records with the marine isotope stratigraphy is a challenge of central importance in Quaternary stratigraphy, particularly in Western Europe where long ...records of glaciation on land areas are particularly rare. Here we demonstrate for the first time the interrelationship of events during the last 1.2
Ma in an ocean-sediment core from the Bay of Biscay (NE Atlantic), SW of the Channel. The identification of discharge variations from tributary river systems to the ‘Fleuve Manche’ palaeoriver during glacio-eustatic sea-level lowstands demonstrates the correlation of the marine sediment stratigraphy to the expansion and recession of the European ice-sheets. The amplitude and chronology of European ice-sheet oscillations since the late Early Pleistocene is discussed and our results demonstrate that the first coalescence of the Fennoscandian and British ice-sheets in the North Sea basin ca 450
ka ago caused a profound change in lowstand European drainage alignment. This change caused a rerouting of Fennoscandian and eastern British ice-sheets-derived meltwaters from northwards into the Nordic Seas to southwards into the eastern North Atlantic thereafter. Besides allowing a thorough synchronisation of the European ice-sheet palaeogeography with the well-dated records of palaeoceanographical changes, our results improve the stratigraphy of the English Channel palaeovalleys and will provide important constraints on paleoclimatic scenarios considering the impact that such rerouting and meltwater surges might have on the stability of the oceanic conveyor belt.
The charge transfer (ionization) of hydrogen Rydberg atoms (n=25-34) incident on a Cu(100) surface is investigated. Unlike fully metallic surfaces, where the Rydberg electron energy is degenerate ...with the conduction band of the metal, the Cu(100) surface has a projected band gap at these energies, and only discrete image states are available through which charge transfer can take place. Resonant enhancement of charge transfer is observed for Rydberg states whose energy matches one of the image states, and the integrated surface ionization signals (signal versus applied field) show clear periodicity as a function of n as the energies come in and out of resonance with the image states. The surface ionization dynamics show a velocity dependence; decreased velocity of the incident H atom leads to a greater mean distance of ionization and a lower field required to extract the ion. The surface ionization profiles for "on resonance" n values show a changing shape as the velocity is changed, reflecting the finite field range over which resonance occurs.
Current debate on the status and character of the Anthropocene is focussed on whether this interval of geological time should be designated as a formal unit of epoch/series rank in the International ...Chronostratigraphic Chart/Geological Time Scale, or whether it is more appropriate for it to be considered as an informal ‘event’ comparable in significance with other major transformative events in deeper geological time. The case for formalizing the Anthropocene as a chronostratigraphical unit with a base at approximately 1950 CE is being developed by the Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy. Here we outline the alternative position and explain why the time‐transgressive nature of human impact on global environmental systems that is reflected in the recent stratigraphical record means that the Anthropocene is better seen not as a series/epoch with a fixed lower boundary, but rather as an unfolding, transforming and intensifying geological event.
The case for formalising the Anthropocene as a chronostratigraphic unit with a base at approximately 1950 CE is being developed by the Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy. Here we outline the alternative position and explain why the time‐transgressive nature of human impact on global environmental systems is more accurately reflected by defining the Anthropocene as a continuing event, with no fixed basal boundary.
MTI is a quantitative MR imaging technique that has recently demonstrated structural integrity differences between controls and patients with HD. Potentially, MTI can be used as a biomarker for ...monitoring disease progression. To establish the value of MTI as a biomarker, we aimed to examine the change in these measures during the course of HD.
From the Leiden TRACK-HD study, 25 controls, 21 premanifest gene carriers, and 21 patients with manifest HD participated at baseline and during a 2-year follow-up visit. Brain segmentation of the cortical gray matter, white matter, caudate nucleus, putamen, pallidum, thalamus, amygdala, and hippocampus was performed by using the automated tools FAST and FIRST in FSL. Individual MTR values were calculated from these regions, and MTR histograms were constructed.
In the premanifest HD group stage "far from disease onset," a significant increase in MTR peak height of the putamen was observed with time. During the manifest HD stage, neither the mean MTR nor the MTR peak height showed a significant change during a 2-year follow-up.
MTI-derived measures are not suitable for monitoring in Huntington disease during a 2-year period because there was no decrease in structural integrity detected in any of the manifest HD groups longitudinally. The finding of increased putaminal MTR peak height in the premanifest far from disease onset group could relate to a predegenerative process, compensatory mechanisms, or aberrant development but should be interpreted with caution until future studies confirm this finding.
M.J. Gibbard et al. comment on the paper by G.J. Rogers (see ibid., vol.15, no.1, p.350-5, 2000). They discuss their application of a different design procedure to the author's four-machine infinite ...bus system. The original author replies to the comments.
The subjects discussed by the panelists at the Panel Session: Recent Applications of Linear Analysis Techniques conducted during the 1998 IEEE PES Summer Meeting are discussed. The subjects include ...control system design, system identification and large scale system applications. Linear analysis techniques are used to a broad range of power system performance issues.
Geomorphological evidence for Pleistocene glaciation has been mapped in the Pindus Mountains of northwest Greece, and the chronology of glaciation in this area has been established through soil ...profile analysis and U‐series dating of secondary carbonates (calcite) formed within glacial deposits. Three glacial stages are evident in the sedimentological and geomorphological records. The earliest and most extensive recorded glaciation predates 350,000 yr B.P. and was characterized by extensive valley glaciers and ice fields. A more recent glaciation occurred before the last interglacial and was characterized by glaciers that reached midvalley positions. The last phase of glaciation in Greece is recorded by small cirque glacier moraines and relict periglacial rock glaciers. The glacial and periglacial sequence on Mount Tymphi has been used in conjunction with a reference parastratotype, the long lacustrine sequence at Ioannina, to provide a chronostratigraphical framework for cold‐stage deposits in Greece. The three glacial stages are formally defined: the Skamnellian Stage, equivalent to the Elsterian Stage of northern Europe and marine isotope stage (MIS) 12; the Vlasian Stage, equivalent to the late Saalian Stage of northern Europe and MIS 6; and the Tymphian Stage, which is equivalent to the Weichselian/Würmian stages of northern Europe and the Alps, respectively, and MIS 5d‐2. This is the first formalized chronostratigraphical framework based on the glacial record to be established for cold stages in the Mediterranean and provides a new platform for paleoclimatological investigations in the region.
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