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  • 1
    Language: English
    In: Journal of Hydrology, 2011, Vol.400(1), pp.58-71
    Description: ► Various methods exist to calculate hydraulic conductivity ( ) from grain size data. ► Grain size based data are suitable for a general aquifer characterization. ► Calculated proved not to be reliable enough for further stochastic analyses. ► Sample heterogeneity caused strong differences between measured and calculated ► Large uncertainties on calculated are introduced by the approximation of porosity. Determination of hydraulic conductivity ( ) and its variation in space is often a major objective of hydrogeological site investigations. However, measurement of at a high spatial resolution in sedimentary aquifers is a challenge. There are a number of field methods that can be used to determine , although they differ greatly in terms of their spatial resolution. One commonly used approach is to estimate from grain size analyses, but the reliability of the resulting estimates is unclear. The aims of this study are to compare frequently used formulas for the determination of from grain size data for a broad range of sediment types and to evaluate how well these methods predict . Sonic sampling was used to obtain minimally disturbed cores in a highly heterogeneous sedimentary aquifer and values of grain size analyses from 108 core samples were calculated. Despite the high correlation of calculated derived from different formulas, mean values differed by several orders of magnitude between the formulas. For the evaluation of the reliability of the estimates, high resolution direct push slug tests (DPSTs) were also performed in the close vicinity of the cores. A high correlation between ln( ) and ln( ) was found for most of the applied formulas. Nevertheless, sample heterogeneity, i.e. the presence of small clay layers in a generally highly permeable sample, led to estimates that were significantly smaller than the estimates. Based on these results, the applied formulas appear to be suitable for an initial assessment of aquifer . However, considering the difference in calculated mean values, results are not sufficiently reliable for the high resolution analyses of variations needed for flow or transport modeling.
    Keywords: Hydraulic Conductivity ; Sieve Analysis ; Grain Size Distribution ; Direct Push Slug Test ; Sonic Sampling ; Bitterfeld ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 2
    Language: English
    In: Journal of Contaminant Hydrology, 2011, Vol.122(1), pp.1-15
    Description: Measuring contaminant flow rates at control cross sections is the most accurate method to evaluate natural attenuation processes in the saturated subsurface. In most instances, point scale measurement is the method of choice due to practical reasons and cost factors. However, at many field sites, the monitoring network is too sparse for a reliable estimation of contaminant and groundwater flow rates. Therefore, integral pumping tests have been developed as an alternative. In this study, we compare mass flow rates obtained by integral pumping test results and point scale data. We compare results of both methods with regard to uncertainties due to estimation errors and mass flow estimations based on two different point scale networks. The differences between benzene and groundwater flow rate estimates resulting from point scale samples and integral pumping tests were 6.44% and 6.97%, respectively, demonstrating the applicability of both methods at the site. Point scale-based data, especially with use of cost efficient Direct-Push technique, can be applied to show the contaminant distribution at a site and may be followed by a denser point scale network or an integral method. Nevertheless, a combination of both methods decreases uncertainties.
    Keywords: Integral Pumping Test ; Point Scale Measurements ; Cstream ; Mass Flow Rate ; Btex ; Direct-Push ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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  • 3
    In: Ground Water, May 2012, Vol.50(3), pp.450-456
    Description: Detailed information on vertical variations in hydraulic conductivity () is essential to describe the dynamics of groundwater movement at contaminated sites or as input data used for modeling. values in high vertical resolution should be determined because tends to be more continuous in the horizontal than in the vertical direction. To determine in shallow unconsolidated sediments and in the vertical direction, the recently developed direct‐push injection logger can be used. The information obtained by this method serves as a proxy for and has to be calibrated to obtain quantitative values of measured vertical profiles. In this study, we performed direct‐push soil sampling, sieve analyses and direct‐push slug tests to obtain values in vertical high resolution. Using the results of direct‐push slug tests, quantitative values obtained by the direct‐push injection logger could be determined successfully. The results of sieve analyses provided lower accordance with the logs due to the inherent limitations of the sieving method.
    Keywords: Hydrogeology ; Environmental Geology ; Aquifers ; Central Europe ; Elbe River ; Europe ; Experimental Studies ; Germany ; Granulometry ; Ground Water ; Hydraulic Conductivity ; Injection ; Measurement ; Mobility ; Pirna Germany ; Pollution ; Preferential Flow ; Sampling ; Saxony Germany ; Sediments ; Soils ; Unconsolidated Materials ; Variations;
    ISSN: 0017-467X
    E-ISSN: 1745-6584
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  • 4
    Language: English
    In: Gut, July 2018, Vol.67(7), pp.1328-1341
    Description: Sorafenib is the only effective therapy for advanced hepatocellular carcinoma (HCC). Combinatory approaches targeting mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK)- and phosphatidylinositol-4,5-bisphosphate-3-kinase (PI3K)/protein-kinase B(AKT) signalling yield major therapeutic improvements. RAS proteins regulate both RAF/MAPK and PI3K/AKT signalling. However, the most important RAS isoform in carcinogenesis, Kirsten rat sarcoma (KRAS), remains unexplored in HCC. Human HCC tissues and cell lines were used for expression and functional analysis. Sorafenib-resistant HCC cells were newly generated. RNA interference and the novel small molecule deltarasin were used for KRAS inhibition both in vitro and in a murine syngeneic orthotopic HCC model. Expression of wild type KRAS messenger RNA and protein was increased in HCC and correlated with extracellular-signal regulated kinase (ERK) activation, proliferation rate, advanced tumour size and poor patient survival. Bioinformatic analysis and reporter assays revealed that KRAS is a direct target of microRNA-622. This microRNA was downregulated in HCC, and functional analysis demonstrated that KRAS-suppression is the major mediator of its inhibitory effect on HCC proliferation. KRAS inhibition markedly suppressed RAF/ERK and PI3K/AKT signalling and proliferation and enhanced apoptosis of HCC cells in vitro and in vivo. Combinatory KRAS inhibition and sorafenib treatment revealed synergistic antitumorigenic effects in HCC. Sorafenib-resistant HCC cells showed elevated KRAS expression, and KRAS inhibition resensitised sorafenib-resistant cells to suppression of proliferation and induction of apoptosis. KRAS is dysregulated in HCC by loss of tumour-suppressive microRNA-622, contributing to tumour progression, sorafenib sensitivity and resistance. KRAS inhibition alone or in combination with sorafenib appears as novel promising therapeutic strategy for HCC.
    Keywords: Hepatocellular Carcinoma ; Molecular Mechanisms ; Antineoplastic Agents -- Therapeutic Use ; Carcinoma, Hepatocellular -- Metabolism ; Liver Neoplasms -- Metabolism ; Micrornas -- Metabolism ; Niacinamide -- Analogs & Derivatives ; Phenylurea Compounds -- Therapeutic Use ; Proto-Oncogene Proteins P21(Ras) -- Physiology
    ISSN: 00175749
    E-ISSN: 1468-3288
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  • 5
    In: Groundwater, November 2012, Vol.50(6), pp.935-942
    Description: Knowledge of site‐specific contaminant transport processes is an essential requirement for performing various tasks concerning the protection and management of groundwater resources. However, prediction of their behavior is often difficult, especially in heterogeneous aquifers because of the lack of information about flow‐ and transport‐governing subsurface structures and parameters. Hence, stochastic approaches have been developed and frequently used. However, extensive modeling studies on sedimentary structures have shown that consideration of hydrogeological subunits and their distribution can be essential for transport modeling. A case study from the intensely investigated Lauswiesen site is used to demonstrate that more accurate predictions are possible with improved knowledge of deterministic structures. Results of this case study using direct‐push injection logging (DPIL) provide a more reliable characterization of hydraulic conductivity than sieve and flow meter data.
    Keywords: Hydrogeology ; Environmental Geology ; Alluvium Aquifers ; Aquifers ; Baden-Wurttemberg Germany ; Central Europe ; Characterization ; Cluster Analysis ; Europe ; Experimental Studies ; Germany ; Ground Water ; Heterogeneous Materials ; Hydraulic Conductivity ; Lauswiesen Site ; Models ; Neckar River ; Permeability ; Pollutants ; Pollution ; Porous Materials ; Preferential Flow ; Pump Tests ; Statistical Analysis ; Stochastic Processes ; Transport ; Tubingen Germany ; Univariate Analysis;
    ISSN: 0017-467X
    E-ISSN: 1745-6584
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  • 6
    Language: English
    In: Environmental Earth Sciences, 2011, Vol.63(6), pp.1239-1249
    Description: The present work focuses on approaches for the characterization of subsurface contamination, which need to be reliable and cost-effective, particularly for extended and remote areas aimed at being redeveloped. Requirements are discussed with respect to specific conditions at megasites, in order to enable site valorization. In a case study, two approaches are compared, comprising (1) conventional site investigation based on historical surveys and concentration measurements at monitoring wells installed in areas suspected of being polluted and (2) the use of direct push (DP) methods covering the complete area. The DP investigation provided information on the contamination distribution and yielded also important information on hydraulic conditions. Statistical analysis of the results applying indicator kriging revealed that the conventional approach is markedly risky when decision-making relies solely on historical and sparse data. The DP campaign remarkably reduced the uncertainty concerning the estimated occurrence of polluted groundwater at the whole site. Furthermore, monitoring measurements are analyzed showing the possible importance of temporal variability. Taking economical consideration into account, DP-based groundwater screening is recommended to obtain either first or complementary information on the entire site. Based on these data, also locations for a long-term monitoring could be selected if temporal variability is assumed relevant.
    Keywords: Groundwater contamination ; Direct-push ; Screening ; Monitoring ; Megasite
    ISSN: 1866-6280
    E-ISSN: 1866-6299
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  • 7
    In: Near Surface Geophysics, December 2014, Vol.12(6), pp.731-737
    Description: Pseudo‐2D surface wave profiling (MASW) has become a powerful state‐of‐the‐art tool for the characterization of near‐surface features in recent years. The rapid gathering and interpretation of surface wave data, i.e. Rayleigh waves, that this method offers is applicable to many investigations and environments. However, most studies only perform unidirectional active surface wave profiling, i.e. without data evaluation by measuring the same profile in the opposite direction. Uncertainties arising from using the MASW method are connected to the one‐dimensional inversion of a two‐dimensional subsurface. Moreover, the occurence of lateral inhomogeneities and dipping layers distort the flat‐layered 1D assumption used in surface wave inversion. In this study, we present data from two different MASW surveys. For both locations, we reveal shot‐geometrical effects and prove the necessity of bidirectional profiling, especially since these check shots can be implemented with only little extra effort. The results of this investigation show that, in general, more attention should be paid to data evaluation.
    Keywords: Applied Geophysics ; Baden ; Baden-Wurttemberg Germany ; Central Europe ; Characterization ; Crust ; Elastic Waves ; Europe ; Geophysical Methods ; Geophysical Profiles ; Geophysical Surveys ; Germany ; Guided Waves ; Lauswiesen Germany ; Multispectral Analysis ; Neckar Germany ; Rayleigh Waves ; Reliability ; Seismic Methods ; Seismic Profiles ; Seismic Waves ; Shallow Depth ; Surface Waves ; Surveys ; Two-Dimensional Models ; Velocity Structure;
    ISSN: 1569-4445
    E-ISSN: 1873-0604
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  • 8
    Language: English
    In: GEOPHYSICS, 05/2017, Vol.82(3), pp.V149-V162
    Description: Probabilistic prediction of 2D or 3D distributions of sparsely measured borehole or direct-push logging data can contribute to solving hydrological, petroleum, or engineering exploration tasks. We use and improve a recently developed workflow constrained by ill-posed geophysical tomography to achieve 2D probabilistic predictions of geotechnical exploration target parameters that could only be measured by 1D borehole or direct-push logging. We use artificial neural networks (ANNs) to find the optimal prediction models between ensembles of equivalent geophysical tomograms and sparsely measured logging data. During the training phase of ANNs, we consider four different training strategies taking into account the logging data uncertainty and geophysical tomographic ambiguity to avoid data overfitting of the ANNs. Thus, we successfully transform the logging data uncertainty and geophysical tomographic reconstruction ambiguity as well as differences in spatial resolution of logging and tomographic models into the probabilistic 2D prediction of our target parameters in a data-driven manner, which allows application of our methodology to any combination of geophysical tomograms and hydrologic, petroleum, or engineering target parameters solely measured in boreholes. To illustrate our workflow, we use an available field data set collected at a field site south of Berlin, Germany, to characterize near-subsurface sedimentary deposits. In this example, we employ cross-borehole tomographic radar-wave velocity, P-wave velocity, and S-wave velocity models to constrain the prediction of tip resistance, sleeve friction, and dielectric permittivity as target parameters.
    Keywords: Applied Geophysics ; Artificial Intelligence ; Berlin Germany ; Body Waves ; Boreholes ; Brandenburg Germany ; Central Europe ; Crosshole Methods ; Data Processing ; Dielectric Properties ; Elastic Waves ; Europe ; Geophysical Methods ; Germany ; Ground-Penetrating Radar ; Neural Networks ; P-Waves ; Prediction ; Probability ; Radar Methods ; Resistivity ; S-Waves ; Seismic Waves ; Statistical Analysis ; Testing ; Three-Dimensional Models ; Tomography ; Two-Dimensional Models ; Uncertainty ; Well-Logging;
    ISSN: 0016-8033
    E-ISSN: 1942-2156
    Source: Society of Exploration Geophysicists (SEG, includes EEGS) (via CrossRef)
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  • 9
    Language: German
    In: Grundwasser, 2011, Vol.16(4), pp.221-234
    Description: Vor etwa zehn Jahren haben die sogenannten Direct-Push -Technologien in Deutschland als „neue“ Technik für die Erkundung des Untergrundes Einzug gehalten und werden seither vielfach in den verschiedensten Bereichen der Untergrunderkundung eingesetzt. Allerdings werden ihre Anwendungsmöglichkeiten noch zum Teil recht konträr diskutiert und eine gewisse Skepsis ist auch nach mehr als zehn Jahren Erfahrung in Deutschland geblieben. Bei genauerer Betrachtung der Anwendungsfelder dieser Technologie fällt auf, dass die Vielfältigkeit der Technologie zwar in einem zunehmenden Maße genutzt wird, in der „Praxis“ aber noch nicht vollständig angekommen zu sein scheint. Und dies obwohl die Technologie in ihrer einfachsten Art – nämlich in Form von Rammkernsondierungen – standardmäßig eingesetzt, aber das Potenzial der Methode nicht genutzt wird. Um diesem Defizit zu begegnen, zielt dieser Beitrag darauf ab, einen umfassenden Überblick über den Stand der Direct-Push -Technologie und deren vielfältigen Anwendungsmöglichkeiten und -limitierungen zu geben. About ten years ago, Direct Push technologies were introduced in Germany as a “new” tool for subsurface characterization. Ever since, they have been frequently used in various fields of site investigations. However, despite over ten years of experience, their application potential is often perceived with scepticism. Closer consideration of the range of applications of this method shows that the technology is indeed being increasingly used, even though it does not seem to be completely accepted in the “consulting world”. This is surprising as Direct Push is already used in Germany in its simplest form—i.e. by percussion coring—on a routine basis. Nonetheless, the full potential of Direct Push has not yet been exploited. This article aims to provide a comprehensive overview on the state of the art of this technology and its various application potentials and limitations.
    Keywords: Direct Push ; Site characterization ; Sampling ; Direct sensing ; Subsurface investigation
    ISSN: 1430-483X
    E-ISSN: 1432-1165
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  • 10
    Language: English
    In: Canadian Geotechnical Journal, 2012, Vol.49(2), p.197(10)
    Description: Every environmental site investigation aims at delineating near-surface (hydro-) stratigraphic units and their characterization. To determine the type and hydraulic properties of sedimentary deposits, direct push (DP) sensor probes and tools are promising methods and are therefore frequently applied to measure high-resolution vertical profiles of soil properties. Given the variety of these tools, the objective of this paper is to compare selected DP tools for the (hydro-) stratigraphic subsurface characterization in a heterogeneous unconsolidated sedimentary aquifer. An overview of current DP applications is given and selected DP tools were tested for reproducibility, as well as their ability to reflect soil variability and to estimate hydraulic conductivity, K. Although resolution differences exist, all of the applied methods captured the main aquifer structure. Correlations of the DP-based K estimates or proxies with DP slug tests (DPST) show that it is possible to describe the aquifer hydraulic structure on less than a metre scale by combining DPST data and continuous DP measurements. Although correlations are site-specific and appropriate DP tools must be chosen, DP is a reliable and efficient alternative for characterizing even strongly heterogeneous sites with complex sedimentary architectures. Key words: direct push, aquifer characterization, hydraulic profiling, cone penetration testing. Les etudes environnementales de sites servent a identifier et caracteriser les unites (hydro-) stratigraphiques pres de la surface. Afin de determiner le type de depots sedimentaires et leurs proprietes hydrauliques, les sondes et outils de poussee directe (PD) font partie des methodes prometteuses, et ainsi sont frequemment appliques pour mesurer a haute resolution les profils verticaux des proprietes des sols. Comme ces outils sont nombreux et varies, l'objectif de cet article est de comparer certains de ces outils de PD pour la caracterisation (hydro-) stratigraphique sous la surface dans un aquifere sedimentaire heterogene et non consolide. Un sommaire des applications courantes de PD est presente, et certains outils ont ete testes pour evaluer leur reproductibilite ainsi que leur capacite a identifier la variabilite des sols et a estimer la conductivite hydraulique, K. Meme si les methodes appliquees different dans leur resolution, elles ont toutes reussi a evaluer la structure de l' aquifere principal. Des correlations entre les estimations de K basees sur la PD ou obtenues indirectement avec des essais de cone en PD (ECPD) demontrent qu'il est possible de decrire la structure hydraulique d'un aquifere a une echelle inferieure au metre en combinant les donnees d' ECPD et les mesures en continu de PD. Malgre que les correlations soient specifiques a un site donne et que les outils de PD appropries doivent etre choisis, la PD est une alternative efficace et fiable pour caracteriser les sites tres heterogenes ayant des architectures sedimentaires complexes. Mots-cles : poussee directe, caracterisation d'aquifere, profilage hydraulique, essai de penetration du cone. [Traduit par la Redaction]
    Keywords: Stratigraphy – Research ; Hydrography – Research ; Aquifers – Properties
    ISSN: 0008-3674
    E-ISSN: 12086010
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