255 research outputs found
100 kyr fluvial cut-and-fill terrace cycles since the Middle Pleistocene in the southern Central Andes, NW Argentina
No full textFluvial fill terraces in intermontane basins are valuable geomorphic archives that can record tectonically and/or climatically driven changes of the Earth-surface process system. However, often the preservation of fill terrace sequences is incomplete and/or they may form far away from their source areas, complicating the identification of causal links between forcing mechanisms and landscape response, especially over multi-millennial timescales. The intermontane Toro Basin in the southern Central Andes exhibits at least five generations of fluvial terraces that have been sculpted into several-hundred-meter-thick Quaternary valley-fill conglomerates. New surface-exposure dating using nine cosmogenic 10Be depth profiles reveals the successive abandonment of these terraces with a 100 kyr cyclicity between 75±7 and 487±34 ka. Depositional ages of the conglomerates, determined by four 26Al/10Be burial samples and U–Pb zircon ages of three intercalated volcanic ash beds, range from 18±141 to 936±170 ka, indicating that there were multiple cut-and-fill episodes. Although the initial onset of aggradation at ∼1 Ma and the overall net incision since ca. 500 ka can be linked to tectonic processes at the narrow basin outlet, the superimposed 100 kyr cycles of aggradation and incision are best explained by eccentricity-driven climate change. Within these cycles, the onset of river incision can be correlated with global cold periods and enhanced humid phases recorded in paleoclimate archives on the adjacent Bolivian Altiplano, whereas deposition occurred mainly during more arid phases on the Altiplano and global interglacial periods. We suggest that enhanced runoff during global cold phases – due to increased regional precipitation rates, reduced evapotranspiration, or both – resulted in an increased sediment-transport capacity in the Toro Basin, which outweighed any possible increases in upstream sediment supply and thus triggered incision. Compared with two nearby basins that record precessional (21-kyr) and long-eccentricity (400-kyr) forcing within sedimentary and geomorphic archives, the recorded cyclicity scales with the square of the drainage basin length.Fil: Tofelde, Stefanie. Universitat Potsdam; Alemania. Deutsches Geo Forschungs Zentrum; AlemaniaFil: Schildgen, Taylor F.. Universitat Potsdam; Alemania. Deutsches Geo Forschungs Zentrum; AlemaniaFil: Savi, Sara. Universitat Potsdam; AlemaniaFil: Pingel, Heiko. Universitat Potsdam; AlemaniaFil: Wickert, Andrew D.. University of Minnesota; Estados UnidosFil: Bookhagen, Bodo. Universitat Potsdam; AlemaniaFil: Wittmann, Hella. Deutsches Geo Forschungs Zentrum; AlemaniaFil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Cottle, John. University of California; Estados UnidosFil: Strecker, Manfred R.. Universitat Potsdam; Alemani
Modelling Interregional Trade of Energy Crops in Eastern Germany
No full textRenewable resources gain in importance in our modern society. The line of reasoning is based on their positive effects on agriculture, the environment and the economy. To support renewable energy from biomass the EU promotes the cultivation of energy crops. A spatial equilibrium model is applied based on the concept of maximizing net welfare, to provide information whether energy crop production competes with food production for land area. The Model of Interregional Trade of Energy Crops (ITEC) refers to Eastern Germany and adjacent areas of Poland. First results show that the regions have enough feedstocks to meet the required demand for food and biofuel production. In many cases both food crops and biofuels are either traded on interregional basis or exported to "Rest of Europe" indicating that there is no competition between food and energy crops. Only green maize for biogas production strongly competes in areas where the crop is required as feed for cattle.Energy crops, spatial equilibrium analysis, interregional trade, International Relations/Trade,
Pliocene Orographic Barrier Uplift in the Southern Central Andes
No full textSedimentary basin fills along the windward flanks of orogenic plateaus are valuable archives of paleoenvironmental change with the potential to resolve the history of surface uplift and orographic barrier formation. The intermontane basins of the southern Central Andes contain thick successions of sedimentary material that are commonly interbedded with datable volcanic ashes. We relate variations in the hydrogen isotopic composition of hydrated volcanic glass (δDg) of Neogene to Quaternary fills in the semiarid intermontane Humahuaca Basin (Eastern Cordillera, northwest Argentina) to spatiotemporal changes in topography and associated orographic effects. δD values from volcanic glass in the basin strata (–117‰ to –98‰) show two main trends that accompany observed tectonosedimentary events in the study area. Between 6.0 and 3.5 Ma, δDg values decrease by ∼17‰; this is associated with surface uplift in the catchment area. After 3.5 Ma, δDg values show abrupt deuterium enrichment, which we associate with (1) the attainment of threshold elevations for blocking moisture transport in the basin-bounding ranges to the east, and (2) the onset of semiarid conditions in the basin. Such orographic barriers throughout the eastern flanks of the Central Andes have impeded moisture transport into the orogen interior; this has likely helped maintain aridity and internal drainage conditions on the adjacent Andean Plateau.Fil: Pingel, Heiko. Universität Potsdam; AlemaniaFil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Mulch, Andreas. Goethe Universitat Frankfurt; Alemania. Biodiversität und Klima Forschungszentrum; AlemaniaFil: Rohrmann, Alexander. Universität Potsdam; AlemaniaFil: Sudo, Masafumi. Universität Potsdam; AlemaniaFil: Strecker, R.. Universität Potsdam; Alemani
Miocene orographic uplift forces rapid hydrological change in the southern central Andes
No full textRainfall in the central Andes associated with the South American Monsoon and the South American Low-Level Jet results from orographic effects on atmospheric circulation exerted by the Andean Plateau and the Eastern Cordillera. However, despite its importance for South American climate, no reliable records exist that allow decoding the evolution of thresholds and interactions between Andean topography and atmospheric circulation, especially regarding the onset of humid conditions in the inherently dry southern central Andes. Here, we employ multi-proxy isotope data of lipid biomarkers, pedogenic carbonates and volcanic glass from the Eastern Cordillera of NW Argentina and present the first long-term evapotranspiration record. We find that regional eco-hydrology and vegetation changes are associated with initiation of moisture transport via the South American Low-Level Jet at 7.6 Ma, and subsequent lateral growth of the orogen at 6.5 Ma. Our results highlight that topographically induced changes in atmospheric circulation patterns, not global climate change, were responsible for late Miocene environmental change in this part of the southern hemisphere. This suggests that mountain building over time fundamentally controlled habitat evolution along the central Andes.Fil: Rohrmann, Alexander. Universitat Potsdam; AlemaniaFil: Sachse, Dirk. Universitat Potsdam; Alemania. German Research Centre for Geosciences; AlemaniaFil: Mulch, Andreas. Goethe Universitat Frankfurt; AlemaniaFil: Pingel, Heiko. Universitat Potsdam; AlemaniaFil: Tofelde, Stefanie. Universitat Potsdam; AlemaniaFil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Strecker, Manfred R.. Universitat Potsdam; Alemani
Neotectonic basin and landscape evolution in the Eastern Cordillera of NW Argentina, Humahuaca Basin (~24°S)
No full textThe intermontane Quebrada de Humahuaca Basin (Humahuaca Basin) in the Eastern Cordillera of the southern Central Andes of NW Argentina (23°–24°S) records the evolution of a formerly contiguous foreland-basin setting to an intermontane depositional environment during the late stages of Cenozoic Andean mountain building. This basin has been and continues to be subject to shortening and surface uplift, which has resulted in the establishment of an orographic barrier for easterly sourced moisture-bearing winds along its eastern margin, followed by leeward aridification. We present new U–Pb zircon ages and palaeocurrent reconstructions suggesting that from at least 6 Ma until 4.2 Ma, the Humahuaca Basin was an integral part of a largely contiguous depositional system that became progressively decoupled from the foreland as deformation migrated eastward. The Humahuaca Basin experienced multiple cycles of severed hydrological conditions and subsequent re-captured drainage, fluvial connectivity with the foreland and sediment evacuation. Depositional and structural relationships among faults, regional unconformities and deformed landforms reveal a general pattern of intrabasin deformation that appears to be associated with different cycles of alluviation and basin excavation in which deformation is focused on basin-internal structures during or subsequent to phases of large-scale sediment removal.Fil: Heiko, Pingel. Universitat Potsdam. Institut fur Erd- und Umweltwissenschaften. Leibniz Center for Surface Process and Climate Studies; AlemaniaFil: Strecker, Manfred R.. Universitat Potsdam. Institut fur Erd- und Umweltwissenschaften. Leibniz Center for Surface Process and Climate Studies; AlemaniaFil: Alonso, Ricardo Narciso. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Cátedra de Mineralogia II; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Schmitt, Axel K.. University of California. Department of Earth and Space Sciences; Estados Unido
In-situ study of emerging metallicity and memory effect on ion-beam bombarded strontium titanate surface:
No full textIn this work we present an investigation of the occurrence of conductivity on the surface of SrTiO3 due to argon ion bombardment. We created a model to describe this process and found that the temperature during the ion milling is a crucial factor for the conductivity. Depending on the temperatures we found surface carrier densities ranging from 1.5*10^18 to 2.6*10^20cm^-3 by just analyzing the conductivity behavior.
Clustering of vacancies goes along with temperature and affects the conductivity significantly. Furthermore we found that ion milling is a gentle way create vacancies because the clustering rate is small compared to annealing samples in high vacuum. The amount of clusters at room temperature was measured to be around 3-4 times higher than at -140C.
We found that samples with a conducting surface change their resistance over time at room temperature due to the ongoing process of oxygen vacancy clustering. This effect may be suppressed by decreasing the temperature.
The bistable switching behavior in oxygen deficient SrTiO3 is shown without any additional doping. The vacancy migration is the major mechanism behind this memory effect. Comparing this behavior with annealed samples in high vacuum shows that the therein present amount of vacancy clusters must be much larger and has a negative effect on the bistable switching behavior.M.S.Includes bibliographical references (p. 83-87)by Heiko Gros
Miocene to quaternary basin evolution at the southeastern Andean plateau (Puna) margin (ca. 24°S lat, northwestern Argentina)
No full textThe Andean Plateau of NW Argentina is a prominent example of a high-elevation orogenic plateau characterized by internal drainage, arid to hyper-arid climatic conditions and a compressional basin-and-range morphology comprising thick sedimentary basins. However, the development of the plateau as a geomorphic entity is not well understood. Enhanced orographic rainout along the eastern, windward plateau flank causes reduced fluvial run-off and thus subdued surface-process rates in the arid hinterland. Despite this, many Puna basins document a complex history of fluvial processes that have transformed the landscape from aggrading basins with coalescing alluvial fans to the formation of multiple fluvial terraces that are now abandoned. Here, we present data from the San Antonio de los Cobres (SAC) area, a sub-catchment of the Salinas Grandes Basin located on the eastern Puna Plateau bordering the externally drained Eastern Cordillera. Our data include: (a) new radiometric U-Pb zircon data from intercalated volcanic ash layers and detrital zircons from sedimentary key horizons; (b) sedimentary and geochemical provenance indicators; (c) river profile analysis; and (d) palaeo-landscape reconstruction to assess aggradation, incision and basin connectivity. Our results suggest that the eastern Puna margin evolved from a structurally controlled intermontane basin during the Middle Miocene, similar to intermontane basins in the Mio-Pliocene Eastern Cordillera and the broken Andean foreland. Our refined basin stratigraphy implies that sedimentation continued during the Late Mio-Pliocene and the Quaternary, after which the SAC area was subjected to basin incision and excavation of the sedimentary fill. Because this incision is unrelated to baselevel changes and tectonic processes, and is similar in timing to the onset of basin fill and excavation cycles of intermontane basins in the adjacent Eastern Cordillera, we suspect a regional climatic driver, triggered by the Mid-Pleistocene Climate Transition, caused the present-day morphology. Our observations suggest that lateral orogenic growth, aridification of orogenic interiors, and protracted plateau sedimentation are all part of a complex process chain necessary to establish and maintain geomorphic characteristics of orogenic plateaus in tectonically active mountain belts.Fil: Pingel, Heiko. Universitat Potsdam; AlemaniaFil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; ArgentinaFil: Altenberger, Uwe. Universitat Potsdam; AlemaniaFil: Cottle, John. University Of California, Santa Barbara;Fil: Strecker, Manfred R.. Universitat Potsdam; Alemani
Handle with Care : Implementation of the List Experiment and Crosswise Model in a Large-Scale Survey on Academic Misconduct
No full textAcknowledgments We thank the anonymous reviewers as well as Alexander Ehlert, Isabel Raabe, and Justus Rathmann for their concise comments and constructive feedback on our work. Co-authors in alphabetical order. Study Design: Julia Jerke, David Johann, Heiko Rauhut, Kathrin Thomas, Antonia Velicu. Coding and Analysis: Julia Jerke, David Johann, Kathrin Thomas, Antonia Velicu. First draft: Julia Jerke, Heiko Rauhut, Kathrin Thomas, Antonia Velicu. Revisions: David Johann, Kathrin Thomas, Antonia Velicu. Final approval of the paper: Julia Jerke, David Johann, Heiko Rauhut, Kathrin Thomas, Antonia Velicu. Funding Information: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research is supported by the Swiss National Science Foundation (SNSF), Starting Grant “CONCISE” BSSGIO 155981 of Heiko Rauhut.Peer reviewe
The Definitive Guide to NetBeans Platform
No full textThe Definitive Guide to NetBeans(t) Platform is a thorough and definitive introduction to the NetBeans Platform, covering all its major APIs in detail, with relevant code examples used throughout. The original German book on which this title is based was well received. The NetBeans Platform Community has put together this English translation, which author Heiko Bock updated to cover the latest NetBeans Platform 6.5 APIs. With an introduction by known NetBeans Platform experts Jaroslav Tulach, Tim Boudreau, and Geertjan Wielenga, this is the most up-to-date book on this topic at the moment. Al
An adaptive system for patient-controlled analgesia vol.1
No full textVolume 2 is the actual data. Please contact the author for this information. Heiko Rudolph [[email protected]] http://www.set.rmit.edu.au/~e55643/Deposited with permission of the author. © 1995 Dr. Heiko E. R. Rudolph.Patient-Controlled Analgesia (PCA) has become accepted as an important means of self-regulated relief from post-surgical pain. In commonly used PCA systems, patients use a hand-held push-button to indicate the presence of pain and initiate a predetermined bolus of drug infusion. A disadvantage of this system is that no means is provided to accommodate variations in the intensity of pain or the sensitivity of the patient to the analgesic in use apart from the frequency of button pushing. A fixed rate background infusion is usually an option. A new adaptive PCA system is proposed to provide improved PCA through the use a variable background infusion, the provision for an extended high range of analgesic dosages and a novel handset which allows patients to rate their pain. The total system is under the control of an expert algorithm and is proposed to overcome some of the shortcomings of current systems. (For complete abstract open document
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