Event-scale floodplain accretion revealed through tree-ring analysis of buried plains cottonwoods,Powder River,MT, USA     

Tara L. Metzger  James E. Pizzuto  Shelia M. Trampush  Jonathan M. Friedman  Derek M. Schook 《地球表面变化过程与地形》2020,45(2):345-360

Six plains cottonwoods along the axis of a meander were excavated to determine if dendrochronology could identify the year and location of germination and date past overbank sedimentation events. Samples from all excavated trees showed clear anatomical changes associated with burial, including increased vessel size, decreased definition of annual ring boundaries, and decreased ring widths. Some of these burial signatures were created by deposition of only a few centimeters of sediment, and most burial events were detected by multiple samples from the same tree. Four of the trees germinated at or near the upper surfaces of bar deposits, while two germinated within thin overbank deposits draped over bar deposits, indicating that germination is closely associated with bars. Dates and inferred thicknesses of overbank sedimentation events are consistent with repeated topographic surveys and data obtained from cesium-137 (¹³⁷Cs) analyses. However, the record of overbank sedimentation extracted from the trees does not entirely reflect the history of past peak discharges documented by stream gaging, largely because individual trees are progressively less likely to be flooded through time as the river migrates farther away. Germination dates and locations closely track past positions of the river channel. Germination elevations and the elevations of the tops of point bars appear to be decreasing with time as the bend migrates, implying vertical incision by Powder River at a rate of 7.1 ± 4.3 mm/yr. The rate of floodplain growth determined by elevation changes decreases progressively through time, ultimately reaching an apparent plateau after 0.8–1.3 m of vertical accretion. While similar patterns of vertical accretion have previously been interpreted as resulting from decreasing flood probability with increasing floodplain elevation, distance from the channel is also a first-order control on vertical floodplain growth. © 2019 John Wiley & Sons, Ltd.  相似文献   

Oxidative stress response of European flounder (Platichthys flesus) to cadmium determined by a custom cDNA microarray     

Sheader DL  Williams TD  Lyons BP  Chipman JK 《Marine environmental research》2006,62(1):33-44

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Essay review: Coastal geomorphology and the coastal landform without a name     

Derek Flinn 《Geological Journal》1994,29(1):81-84

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Essay review: Kinematic analysis–-pure nonsense or simple nonsense?     

Derek Flinn 《Geological Journal》1994,29(3):281-284

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Scientific detector workshop 2022 on-sky performance verification of near-infrared e−APD technology for wavefront sensing and demonstration of e−APD pixel performance to improve the sensitivity of large science focal planes     

Gert Finger  Frank Eisenhauer  Reinhard Genzel  Christopher Mandla  Ian Baker  Domingo Alvarez  Antonio Amorim  Wolfgang Brandner  Christophe Dupuy  Casey Deen  Derek Ives  Leander Mehrgan  Manfred Meyer  Karin Perraut  Guy Perrin  Jörg Stegmeier  Christian Straubmeier  Harald J. Weller  Vincent Isgar 《Astronomische Nachrichten》2023,344(8-9):e20230069

Near-infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high-speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state-of-the-art conventional CMOS technology of near-infrared arrays as has been attempted previously. A total of five near-infrared SAPHIRA 320 × 256 pixel HgCdTe e⁻APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is m_k = 19, which is made possible with ADP technology. New avalanche photo-diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10⁻³ e⁻/s have been demonstrated with 1Kx1K e⁻APD arrays and 2Kx2K e⁻APD arrays have already been developed, the possibilities and adaptations of e⁻APD technology to provide noiseless large-format science-grade arrays for long integration times are also discussed.  相似文献