A5050880883- Groundwater flow and contamination studies
- Karst Systems and Hydrogeology
- Hydraulic Fracturing and Reservoir Analysis
- Groundwater and Isotope Geochemistry
- CO2 Sequestration and Geologic Interactions
- Hydrocarbon exploration and reservoir analysis
- Hydrology and Watershed Management Studies
- Enhanced Oil Recovery Techniques
- Seismic Imaging and Inversion Techniques
- Groundwater and Watershed Analysis
- Wireless Communication Networks Research
- Reservoir Engineering and Simulation Methods
- Geothermal Energy Systems and Applications
- IPv6, Mobility, Handover, Networks, Security
- Drilling and Well Engineering
- ICT Impact and Policies
- Rock Mechanics and Modeling
- Methane Hydrates and Related Phenomena
- Advanced MIMO Systems Optimization
- Geophysical Methods and Applications
- Atmospheric and Environmental Gas Dynamics
- earthquake and tectonic studies
- Landslides and related hazards
- Digital Innovation in Industries
- Radioactive element chemistry and processing
University of Göttingen
2015-2024
Leibniz Institute for Applied Geophysics
2023-2024
LVR-Klinik Köln
2013-2022
University of California, San Diego
2015
Universitätsmedizin Göttingen
2014
Universitätsmedizin Greifswald
2012
Ball State University
2008
GFZ Helmholtz Centre for Geosciences
2008
Gesellschaft für wissenschaftliche Datenverarbeitung mbH Göttingen
2007
Friedrich Schiller University Jena
2000-2006
Summary In‐frame deletions were introduced into each of the eight genes hyc operon coding for products required formation formate hydrogenlyase (FHL) system. The transferred to chromosome and resulting mutants analysed development dehydrogenase H hydrogenase 1, 2 3 activity. It was found that hycA , promoter‐proximal gene, is a regulatory gene it codes product counteracting transcriptional activation by FhlA. Deletions within hycB hycH specifically affected activity or activity, both. None...
Summary An 8kb segment of DNA from the 58/59 min region E. coli chromosome, which complements defect a mutant devoid hydrogenase 3 activity, has been sequenced. Eight open reading frames were identified are arranged in transcriptional unit; all transcribed and translated vivo T7 promoter/polymerase system. Analysis amino acid sequences derived nucleic revealed that one them, frame 5 (0RF5), exhibits significant sequence similarity to conserved regions large subunit Ni/Fe hydrogenases. Two (...
This paper is intended to provide insight into the controlling mechanisms of karst genesis based on an advanced modeling approach covering characteristic hydraulics in systems, dissolution kinetics, and associated temporal decrease flow resistance. Karst water strongly governed by interaction between a highly conductive low storage conduit network low‐conductive high‐storage rock matrix under variable boundary conditions. Only if this coupling considered can appropriate representation other...
The products of the hyp operon genes are essential for formation catalytically active hydrogenases in Escherichia coli. At least one these auxiliary proteins, HYPB, appears to be involved nickel liganding hydrogenase apoprotein, since mutations hypB can phenotypically suppressed by high concentrations medium (R. Waugh and D. H. Boxer, Biochimie 68:157-166, 1986). To approach identification specific function we overexpressed gene purified characterized product. HYPB is a homodimer 31.6-kDa...
Due to its extreme salinity and high Mg concentration the Dead Sea is characterized by a very low density of cells most which are Archaea. We discovered several underwater fresh brackish water springs in harboring dense microbial communities. provide first characterization these communities, discuss their possible origin, hydrochemical environment, energetic resources putative biogeochemical pathways they mediating. Pyrosequencing 16S rRNA gene community fingerprinting methods showed that...
Karst aquifers provide drinking water for 10% of the world's population, support agriculture, groundwater-dependent activities, and ecosystems. These are characterised by complex groundwater-flow systems, hence, they extremely vulnerable protecting them requires an in-depth understanding systems. Poor data accessibility has limited advances in karst research realistic representation processes large-scale hydrological studies. In this study, we present World Spring hydrograph (WoKaS)...
Abstract A method to estimate reactive transport parameters as well geometric conduit from a multitracer test in karst aquifer is provided. For this purpose, calibration strategy was developed applying the two‐region nonequilibrium model CXTFIT. The ambiguity of reduced by first calibrating with respect conservative tracer breakthrough and later transferring calibration. were only allowed be within defined sensible range get reasonable values. This applied curves obtained large‐scale test,...
This paper presents a numerical model study simulating the early karstification of single conduit embedded in fissured system. A hybrid continuum‐discrete pipe flow (CAVE) is used for modeling. The effects coupling two systems on type and duration are studied different boundary conditions. Assuming fixed head boundaries at both ends conduit, via exchange between system leads to an enhanced evolution conduit. effect valid over wide range initial diameters, accelerated by factor about 100 as...
Abstract A tracer test in a carbonate aquifer is analyzed using the method of moments and two analytical advection‐dispersion models (ADMs) as well numerical model. The model coupled continuum‐pipe flow transport that accounts for different components karstified aquifers, i.e., rapid often turbulent conduit Darcian fissured porous rock. All techniques employed provide reasonable fits to breakthrough curve (TBC) measured at spring. resulting parameter estimates are compared investigate how...
Well‐developed karst aquifers consist of highly conductive conduits and a relatively low permeability fractured and/or porous rock matrix therefore behave as dual‐hydraulic system. Groundwater flow within permeable strata is rapid transient depends on local conditions, i.e., pressurized or nonpressurized flow. The characterization necessary challenging task because information about hydraulic spatial conduit properties poorly defined unknown. To investigate aquifers, stresses such large...
In this study the potential of an inversion approach based on hydraulic travel time and attenuation tomography was assessed. Both are transformation transient groundwater flow equation into eikonal using asymptotic approach. The allows calculation pressure propagation along trajectories, which is computationally efficient. time‐based approaches naturally complementary: times determined by diffusivity, a combination conductivity specific storage, whereas solely storage. our tomographical...
The modeling of groundwater flow in karst aquifers is a challenge due to the extreme heterogeneity its hydraulic parameters and duality their discharge behavior, that is, rapid response highly conductive conduits delayed drainage low‐permeability fractured matrix after recharge events. There are number different approaches for simulation dynamics, applicable aquifer as well problem types, ranging from continuum models double discrete hybrid models. This study presents application an...