3D architecture of cyclic-step and antidune deposits in glacigenic subaqueous fan and delta settings: Integrating outcrop and ground-penetrating radar data

Bedforms related to supercritical flows are increasingly recognised as important constituents of many depositional environments, but outcrop studies are commonly hampered by long bedform wavelengths and complex three-dimensional geometries. We combined outcrop-based facies analysis with ground-penetrating radar (GPR) surveys to analyse the 3D facies architecture of subaqueous ice-contact fan and glacifluvial delta deposits. The studied sedimentary systems were deposited at the margins of the Middle Pleistocene Scandinavian ice sheets in Northern Germany. Glacifluvial Gilbert-type deltas are characterised by steeply dipping foreset beds, comprising cyclic-step deposits, which alternate with antidune deposits. Deposits of cyclic steps consist of lenticular scours infilled by backset cross-stratified pebbly sand and gravel. The GPR sections show that the scour fills form trains along the delta foresets, which can locally be traced for up to 15 m. Perpendicular and oblique to palaeoflow direction, these deposits appear as troughs with concentric or low-angle cross-stratified infills. Downflow transitions from scour fills into sheet-like low-angle cross-stratified or sinusoidally stratified pebbly sand, deposited by antidunes, are common. Cyclic steps and antidunes were deposited by sustained and surge-type supercritical density flows, which were related to hyperpycnal flows, triggered by major meltwater discharge or slope-failure events. Subaqueous ice-contact fan deposits include deposits of progradational scour fills, isolated hydraulic jumps, antidunes and (humpback) dunes. The gravel-rich fan succession consists of vertical stacks of laterally amalgamated pseudo-sheets, indicating deposition by pulses of waning supercritical flows under high aggradation rates. The GPR sections reveal the large-scale architecture of the sand-rich fan succession, which is characterised by lobe elements with basal erosional surfaces associated with scours filled with backsets related to hydraulic jumps, passing upwards and downflow into deposits of antidunes and (humpback) dunes. The recurrent facies architecture of the lobe elements and their prograding and retrograding stacking pattern are interpreted as related to autogenic flow morphodynamics

Ice-marginal forced regressive deltas in glacial lake basins: geomorphology, facies variability and large-scale depositional architecture

This study presents a synthesis of the geomorphology, facies variability and depositional architecture of ice-marginal deltas affected by rapid lake-level change. The integration of digital elevation models, outcrop, borehole, ground-penetrating radar and high-resolution shear-wave seismic data allows for a comprehensive analysis of these delta systems and provides information about the distinct types of deltaic facies and geometries generated under different lake-level trends. The exposed delta sediments record mainly the phase of maximum lake level and subsequent lake drainage. The stair-stepped profiles of the delta systems reflect the progressive basinward lobe deposition during forced regression when the lakes successively drained. Depending on the rate and magnitude of lake-level fall, fan-shaped, lobate or more digitate tongue-like delta morphologies developed. Deposits of the stair-stepped transgressive delta bodies are buried, downlapped and onlapped by the younger forced regressive deposits. The delta styles comprise both Gilbert-type deltas and shoal-water deltas. The sedimentary facies of the steep Gilbert-type delta foresets include a wide range of gravity-flow deposits. Delta deposits of the forced-regressive phase are commonly dominated by coarse-grained debrisflow deposits, indicating strong upslope erosion and cannibalization of older delta deposits. Deposits of supercritical turbidity currents are particularly common in sand-rich Gilbert-type deltas that formed during slow rises in lake level and during highstands. Foreset beds consist typically of laterally and vertically stacked deposits of antidunes and cyclic steps. The trigger mechanisms for these supercritical turbidity currents were both hyperpycnal meltwater flows and slope-failure events. Shoal-water deltas formed at low water depths during both low rates of lake-level rise and forced regression. Deposition occurred from tractional flows. Transgressive mouthbars form laterally extensive sand-rich delta bodies with a digitate, multi-tongue morphology. In contrast, forced regressive gravelly shoal-water deltas show a high dispersion of flow directions and form laterally overlapping delta lobes. Deformation structures in the forced-regressive ice-marginal deltas are mainly extensional features, including normal faults, small graben or half-graben structures and shear-deformation bands, which are related to gravitational delta tectonics, postglacial faulting during glacial-isostatic adjustment, and crestal collapse above salt domes. A neotectonic component cannot be ruled out in some cases. © 2018 The Authors. Boreas published by John Wiley & Sons Ltd on behalf of The Boreas Collegiu

Economic Assessment of Autonomous Electric Microtransit Vehicles

There is rapidly growing interest in autonomous electric vehicles due to their potential in improving safety, accessibility, and environmental outcomes. However, their market penetration rate is dependent on costs. Use of autonomous electric vehicles for shared-use mobility may improve their cost competitiveness. So far, most of the research has focused on the cost impact of autonomy on taxis and ridesourcing services. Singapore is planning for island-wide deployment of autonomous vehicles for both scheduled and on-demand services as part of their transit system in the year 2030. TUMCREATE developed an autonomous electric vehicle concept, a microtransit vehicle with 30-passenger capacity, which can complement the existing bus transit system. This study aims to determine the cost of autonomous electric microtransit vehicles and compare them to those of buses. A total cost of ownership (TCO) approach was used to compare the lifecycle costs. It was shown that although the acquisition costs of autonomous electric vehicles are higher than those of their conventional counterparts, they can reduce the TCO per passenger-km up to 75% and 60% compared to their conventional counterparts and buses, respectively. Document type: Articl

Über die Frequenzabhängigkeit elektrischer Bodeneigenschaften und ihr Einfluss auf das Bodenradar

Ground-Penetrating Radar (GPR) is sensitive to changes of electrical soil properties. These properties can become strongly frequency-dependent, even so they are considered constant in many applications. Analysis of radargrams provided evidence that radar waves propagating in moist loamy and clayey soils underlie strong absorption and dispersion effects. The energy absorption together with the wavelet distortion can reach a degree that even shallow buried objects, as for instance in case of landmine or utility detection, cannot be detected by GPR. In this context, the question on the physical origin and extent of individual dielectric relaxation and conduction mechanisms arose and how they affect GPR. Furthermore, the demand for a prognosis facility emerged to predict the GPR performance with respect to the soil. As the topic has barely been analyzed in the past, the study aims to fill this gap using a combination of field measurements, extensive laboratory investigations and numerical simulations with a variety of soils. To address the causes of absorption and dispersion, electrical properties of soils in the GPR frequency range were analyzed using dielectric spectroscopy. The different electrical loss-mechanisms were separated from each other by fitting a generalized dielectric response model to the data. The very broadband distribution of low-frequency relaxations showed severe impact on GPR especially in moist clayey soils. In order to resolve the relaxation parameters of these processes, the high-frequency dielectric spectroscopy data were combined with low frequency Spectral Induced Polarization (SIP). A combined permittivity and conductivity model (CPCM) was developed that enables to accurately explain the extraordinary large spectrum. Based on dielectric spectroscopy data of the soils, an extensive GPR simulation study was carried out. The measured frequency-dependent electrical soil properties were incorporated into a FDTD code using a multi-relaxation term decomposition. The simulations showed that in dispersive soils a precise description of the electrical soil parameters is essential in order to produce realistic results. Simplified assumptions can only be made for sandy soils. As a practical result of this thesis, a method is presented that enables to predict the GPR performance in the field using a conventional moisture sensor. The method is based on the time-domain reflectometry (TDR) principle and incorporates not only losses due to the dc-conductivity, but also dielectric relaxation losses in the soil.Das Georadar (GPR) ist sensitiv gegenüber Änderungen der elektrischen Bodeneigenschaften. Hierbei können diese Eigenschaften stark von der Frequenz abhängen, obwohl sie bei vielen Anwendungen als konstant angenommen werden. Bei der Auswertung von Radargrammen konnte nachgewiesen werden, dass die Ausbreitung von Radarwellen in feuchten, tonhaltigen und schluffigen Böden starken Absorptions- und Dispersionseffekten unterliegt. Die Energieabsorption in Verbindung mit der Verzerrung des Nutzsignals kann dabei so stark werden, dass selbst oberflächennah vergrabene Objekte, wie zum Beispiel im Falle der Detektion von Landminen- oder von Versorgungsleitungen, mit Hilfe des GPRs nicht mehr detektiert werden können. In diesem Zusammenhang kommt die Frage über den physikalischen Ursprung und das Ausmaß der einzelnen dielektrischen Relaxations- und elektrischen Leitungsmechanismen auf und in wieweit diese das GPR beeinflussen. Zusätzlich besteht der Bedarf einer Prognosemöglichkeit, um die GPR Performance in Abhängigkeit vom Boden zu beurteilen. Da dieses Gebiet in der Vergangenheit nur unzureichend analysiert wurde, versucht diese Arbeit dazu beizutragen, die Lücke durch eine Kombination aus Feldmessungen, umfangreichen Labormessungen und numerischen Simulationen an einer Vielzahl von Böden zu schließen. Um den Ursachen der Absorption und Dispersion auf den Grund zu gehen, wurden die elektrischen Eigenschaften von Böden mit Hilfe der dielektrischen Spektroskopie im Frequenzbereich des GPRs untersucht. Durch Anpassen eines generalisierten dielektrischen Antwortmodells an die Daten konnten die unterschiedlichen elektrischen Verlustmechanismen voneinander getrennt werden. Die sehr breitbandige Verteilung niederfrequenter Relaxationen zeigte speziell bei feuchten und tonhaltigen Böden einen starken Einfluß auf die GPR Performance. Um die Relaxationsparameter dieser Prozesse näher aufzulösen, wurden die hochfrequenten Daten der dielektrischen Spektroskopie mit niederfrequenten Messungen der Spektralen Induzierten Polarisation (SIP) kombiniert. Ein kombiniertes Permittivitäts- und Leitfähigkeitsmodel (CPCM) wurde entwickelt, welches ermöglicht, das außergewöhnlich große Spektrum präzise zu beschreiben. Basierend auf der dielektrischen Spektroskopie der Böden, wurde eine umfassende Studie mit GPR Simulationen durchgeführt. Die frequenzabhängigen elektrischen Bodeneigenschaften wurden mit Hilfe einer Zerlegung in Multi-Relaxationsterme in einem FDTD Code berücksichtigt. Die Simulationen deuten darauf hin, dass in dispersiven Böden eine genaue Beschreibung der elektrischen Bodenparameter unumgänglich ist, um realistische Ergebnisse zu erhalten. Vereinfachte Annahmen können lediglich für sandige Böden getroffen werden. Als praktisches Resultat stellt diese Arbeit ein Verfahren vor, welches die Vorhersage der GPR Performance mit Hilfe eines konventionellen Feuchtigkeitssensors im Feld erlaubt. Die Methode basiert auf dem Prinzip der Zeitbereichs-Reflektometrie (TDR) und bezieht nicht nur Gleichstromverluste, sondern ebenso Verluste aufgrund dielektrischer Relaxationen im Boden mit ein

From exploration to operation: research developments in deep geothermal energy

International audienc

Economic Assessment of Autonomous Electric Microtransit Vehicles

There is rapidly growing interest in autonomous electric vehicles due to their potential in improving safety, accessibility, and environmental outcomes. However, their market penetration rate is dependent on costs. Use of autonomous electric vehicles for shared-use mobility may improve their cost competitiveness. So far, most of the research has focused on the cost impact of autonomy on taxis and ridesourcing services. Singapore is planning for island-wide deployment of autonomous vehicles for both scheduled and on-demand services as part of their transit system in the year 2030. TUMCREATE developed an autonomous electric vehicle concept, a microtransit vehicle with 30-passenger capacity, which can complement the existing bus transit system. This study aims to determine the cost of autonomous electric microtransit vehicles and compare them to those of buses. A total cost of ownership (TCO) approach was used to compare the lifecycle costs. It was shown that although the acquisition costs of autonomous electric vehicles are higher than those of their conventional counterparts, they can reduce the TCO per passenger-km up to 75% and 60% compared to their conventional counterparts and buses, respectively

Visualisation and analysis of shear-deformation bands in unconsolidated Pleistocene sand using ground-penetrating radar: Implications for paleoseismological studies

Deformation bands in unconsolidated sediments are of great value for paleoseismological studies in sedimentary archives. Using ground-penetrating radar (GPR), we investigated an array of shear-deformation bands that developed in unconsolidated Pleistocene glacifluvial Gilbert-type delta sediments. A dense grid (spacing 0.6 m) of GPR profiles was measured on top of a 20 m-long outcrop that exposes shear-deformation bands. Features in the radargrams could be directly tied to the exposure. The shear-deformation bands are partly represented by inclined reflectors and partly by the offset of reflections at delta clinoforms. 3-D interpretation of the 2-D radar sections shows that the bands have near-planar geometries that can be traced throughout the entire sediment volume. Thin sections of sediment samples show that the analysed shear-deformation bands have a denser grain packing than the host sediment. Thus they have a lower porosity and smaller pore sizes and therefore, in the vadose zone, the deformation bands have a higher water content due to enhanced capillary forces. This, together with the partially-developed weak calcite cementation and the distinct offset along the bands, are likely the main reasons for the clear and unambiguous expression of the shear-deformation bands in the radar survey. The study shows that deformation-band arrays can clearly be detected using GPR and quickly mapped over larger sediment volumes. With the 3-D analysis, it is further possible to derive the orientation and geometry of the bands. This allows correlation of the bands with the regional fault trend. Studying deformation bands in unconsolidated sediments with GPR is therefore a powerful approach in paleoseismological studies. Based on our data, we postulate that the outcrop is part of a dextral strike-slip zone that was reactivated by glacial isostatic adjustment

Chlamydia infection depends on a functional MDM2-p53 axis.

Chlamydia, a major human bacterial pathogen, assumes effective strategies to protect infected cells against death-inducing stimuli, thereby ensuring completion of its developmental cycle. Paired with its capacity to cause extensive host DNA damage, this poses a potential risk of malignant transformation, consistent with circumstantial epidemiological evidence. Here we reveal a dramatic depletion of p53, a tumor suppressor deregulated in many cancers, during Chlamydia infection. Using biochemical approaches and live imaging of individual cells, we demonstrate that p53 diminution requires phosphorylation of Murine Double Minute 2 (MDM2; a ubiquitin ligase) and subsequent interaction of phospho-MDM2 with p53 before induced proteasomal degradation. Strikingly, inhibition of the p53-MDM2 interaction is sufficient to disrupt intracellular development of Chlamydia and interferes with the pathogen's anti-apoptotic effect on host cells. This highlights the dependency of the pathogen on a functional MDM2-p53 axis and lends support to a potentially pro-carcinogenic effect of chlamydial infection