Zero-Offset VSP Monitoring of CO2Storage: Impedance Inversion and Wedge Modelling at the Ketzin Pilot Site

At the CO2 storage pilot site near the town of Ketzin (35 km west of Berlin, Germany) the sandstone reservoir at 630 m–650 m depth is thin and heterogeneous. The time-lapse analysis of zero-offset VSP measurements shows that CO2-induced amplitude changes can be observed on near-well corridor stacks. Further, we investigate whether CO2-induced amplitude changes in the monitoring data can be used to derive geometrical and petrophysical parameters governing the migration of CO2 within a brine saturated sandstone aquifer. 2D seismic-elastic modelling is done to test the processing workflow and to perform a wedge modelling study for estimation of the vertical expansion of the CO2 plume. When using the NRMS error as a measure for the similarity between the modelled and recorded repeat traces, the best match is achieved for a plume thickness of 6-7 m within the reservoir sandstone of 8 m thickness. With band limited impedance inversion a velocity reduction at the top of the reservoir of 30%, influenced by casing reverberations as well as CO2 injection, is found. The relation of seismic amplitude to CO2 saturated layer thickness and CO2-induced changes in P-wave velocities are important parameters for the quantification of the injected CO2 volume

Rayleigh-to-shear wave conversion at the tunnel face - from 3D-FD modeling to ahead-of-drill exploration

For a safe tunnel excavation it is important to predict lithological and structural heterogeneities ahead of the construction. conventional tunnel seismic prediction systems utilize body waves (P- and S-waves) that are directly generated at the tunnel walls or near the cutter head of the tunnel boring machine (TBM). In this work we propose a new prediction strategy that has been discovered by 3-D elastic finite-difference (FD) modeling: Rayleigh waves arriving at the front face are converted into high amplitude S-waves propagating further ahead. Reflected or backscattered S-waves are converted back into Rayleigh waves which can be recorded along the side walls. We name these waves RSSR waves. In our approach the front face acts as a S-wave transceiver. One technical advantage is that both the sources and the receivers may be placed behind the cutter head of the TBM. The modeling reveals that the RSSR waves exhibit significantly higher amplitudes than the directly reflected body waves. The excavation damage zone causes dispersion of the RSSR wave leading to multi-modal reflection response. For the detection of geological interfaces ahead RSSR waves recorded along the side walls are corrected for dispersion and stacked. From the arrival times the distance to the S-S reflection point can be estimated. A recurrent application, while the tunnel approaches the interface, allows one to quantify the orientation of the reflecting interfaces as well. Our approach has been successfully verified in a field experiment at the Piora adit of the Gotthard base tunnel. The distance to the Piora fault zone estimated from stacked RSSR events agrees well with the information obtained by geological surveying and exploratory drilling

Distribution and Characteristics of Listeria spp. in Pigs and Pork Production Chains in Germany

Listeria (L.) monocytogenes is a foodborne pathogen that can cause disease, mainly in elderly, pregnant or immunocompromised persons through consumption of contaminated food, including pork products. It is widespread in the environment and can also be found in asymptomatic carrier animals, for example, in different tissues of pigs. To learn more about their nature, 16 Listeria spp. isolates found in tonsils and intestinal content of pigs and 13 isolates from the slaughterhouse environment were characterized using next-generation sequencing (NGS). A wide distribution of clonal complexes was observed in pigs, as well as in the pork production chain, suggesting multiple sources of entry. Hypervirulent clones were found in pig tonsils, showing the potential risk of pigs as source of isolates causing human disease. The presence of closely related isolates along the production chain suggests a cross-contamination in the slaughterhouse or recontamination from the same source, strengthening the importance of efficient cleaning and disinfection procedures. The phenotypical antimicrobial resistance status of L. monocytogenes isolates was examined via broth microdilution and revealed a low resistance level. Nevertheless, genotypical resistance data suggested multiple resistances in some non-pathogenic L. innocua isolates from pig samples, which might pose a risk of spreading resistances to pathogenic species

Seismic anisotropy of Opalinus Clay: tomographic investigations using the infrastructure of an underground rock laboratory (URL)

Seismic anisotropy and attenuation make claystone formations difficult to characterize. On the other hand, in many geotechnical environments, precise knowledge of structure and elastic properties of clay formations is needed. In crystalline and rock salt underground structures, high-resolution seismic tomography and reflection imaging have proven a useful tool for structural and mechanical characterization at the scale of underground infrastructure (several deca- to hundreds of meters). This study investigates the applicability of seismic tomography for the characterization of claystone formations from an underground rock laboratory under challenging on-site conditions including anisotropy, strong attenuation and restricted acquisition geometry. The seismic tomographic survey was part of a pilot experiment in the Opalinus Clay of the Mont Terri Rock Laboratory, using 3-component geophones and rock anchors, which are installed 2 m within the rock on two levels, thus suppressing effects caused by the excavation damage zone. As a source, a pneumatic impact source was used. The survey covers two different facies types (shaly and carbonate-rich sandy), for which the elliptical anisotropy is calculated for direct ray paths by fitting an ellipse to the separated data for each facies. The tomographic inversion was done with a code providing a good grid control and enabling to take the seismic anisotropy into account. A-priori anisotropy can be attributed to the grid points, taking various facies types or other heterogeneities into account. Tomographic results, compared to computations using an isotropic velocity model, show that results are significantly enhanced by considering the anisotropy and demonstrate the ability of the approach to characterize heterogeneities of geological structures between the galleries of the rock laboratory.BMBF, 02NUK053D, Verbundprojekt iCross: Integrität von Endlagersystemen für radioaktive Abfälle - Skalenübergreifendes Systemverständnis und Systemanalyse, Teilprojekt

Seismic prediction ahead of a tunnel face - Modeling, field surveys, geotechnical interpretation

An important precondition for underground construction is a detailed knowledge of the soil and/or rock conditions in the area of the construction. In order to overcome existing limitations in classical exploration methods, research and development for exploration ahead of a tunnel face focuses on: hardware development for excavation integrated measurements, modelling and processing of data measured under these specific circumstances, and integrative interpretation of seismic results with other data from the excavation, from geological mapping, and from exploratory drilling, where available. Finite difference modelling of seismic wavefields around tunnels has shown the general feasibility of seismic measurements for imaging structures ahead of a tunnel face. The modelling results were confirmed by field measurements in various tunnel sites. The integrated interpretation of seismic data with all available geological and geotechnical information is currently in the state of development and aims, in the middle to long term perspective, at an “a priori” detection of structures ahead of the face

Laparoscopic Heller Myotomy Versus Endoscopic Balloon Dilatation for the Treatment of Achalasia A Network Meta-Analysis

Objective: Comparison of short-and long-term effects after laparoscopic Heller myotomy (LHM) and endoscopic balloon dilation (EBD) considering the need for retreatment. Background: Previously published studies have indicated that LHM is the most effective treatment for Achalasia. In contrast to that a recent randomized trial found EBD equivalent to LHM 2 years after initial treatment. Methods: A search in Medline, PubMed, and Cochrane Central Register of Controlled Trials was conducted for prospective studies on interventional achalasia therapy with predefined exclusion criteria. Data on success rates after the initial and repeated treatment were extracted. An adjusted network meta-analysis and meta-regression analysis was used, combined with a headto-head comparison, for follow-up at 12, 24, and 60 months. Results: Sixteen studies including results of 590 LHM and EBD patients were identified. Odds ratio (OR) was 2.20 at 12 months (95% confidence interval: 1.18-4.09; P = 0.01); 5.06 at 24 months (2.61-9.80; P < 0.00001) and 29.83 at 60 months (3.96-224.68; P = 0.001). LHM was also significantly superior for all time points when therapy included re-treatments , and 17.90 (2.17-147.98); P ≤ 0.01 for all comparisons) Complication rates were not significantly different. Meta-regression analysis showed that amount of dilations had a significant impact on treatment effects (P = 0.009). Every dilation (up to 3) improved treatment effect by 11.9% (2.8%-21.8%). Conclusions: In this network meta-analysis, LHM demonstrated superior short-and long-term efficacy and should be considered first-line treatment of esophageal achalasia. Keywords: achalasia, economic cost, endoscopy, esophagus, health, idiopathic achalasia, laparoscopic surgery, meta-analysis, motility disorders, network meta-analysis, review, surgery (Ann Surg 2013;258:943-952 A chalasia is a rare esophageal motility disorder caused by degeneration of the myenteric plexus, resulting in esophageal dysmotility and incomplete lower esophageal sphincter relaxation. The disease is likely caused by a virus-induced autoimmune response, but this is still debated. 1 The incidence in the Western world is 1/100 000. 2-4 Treatment can be pharmacological, endoscopic, or surgical. Pharmacological treatment is only marginally effective and is reserved for patients with mild symptoms or who refuse other treatments. 7-9 Several studies and a large meta-analysis have indicated that laparoscopic Heller myotomy (LHM) is the most effective treatment for achalasia. 3,4,10 However, a recent large prospective randomized controlled trial (RCT) comparing EBD and LHM has challenged this view. 11 This study found similar success rates for EBD and LHM 2 years after initial treatment. However, the number of EBD interventions per patient was notably higher than other studies. 3,11 The purpose of this meta-analysis is to determine which treatment is most effective at relieving symptoms and to further clarify the impact of retreatments for patients with achalasia. METHODS This meta-analysis was registered in the international register of systematic reviews (PROSPERO) (CRD42012002071). 12 Search Strategy and Trial Selection A prospective search of Medline, PubMed, and Cochrane Central Register of Controlled Trials was performed to identify relevant publications. The search keyword was "Esophageal Achalasia." Subsequently, the search was limited by the terms "Human," "Clinical Trial," and publication language "English." Publications from 1975 through October 2011 were considered for review To obtain indirect evidence by adjusted network meta-analysis, relative evidence is needed (LHM vs X; EBD vs X). Therefore, success rates were compared with those of either EBTI or open Heller myotomy (OHM). Direct evidence was achieved from head-to-hea

Impact of wet-lab protocols on quality of whole-genome short-read sequences from foodborne microbial pathogens

For successful elucidation of a food-borne infection chain, the availability of high-quality sequencing data from suspected microbial contaminants is a prerequisite. Commonly, those investigations are a joint effort undertaken by different laboratories and institutes. To analyze the extent of variability introduced by differing wet-lab procedures on the quality of the sequence data we conducted an interlaboratory study, involving four bacterial pathogens, which account for the majority of food-related bacterial infections: Campylobacter spp., Shiga toxin-producing Escherichia coli, Listeria monocytogenes, and Salmonella enterica. The participants, ranging from German federal research institutes, federal state laboratories to universities and companies, were asked to follow their routine in-house protocols for short-read sequencing of 10 cultures and one isolated bacterial DNA per species. Sequence and assembly quality were then analyzed centrally. Variations within isolate samples were detected with SNP and cgMLST calling. Overall, we found that the quality of Illumina raw sequence data was high with little overall variability, with one exception, attributed to a specific library preparation kit. The variability of Ion Torrent data was higher, independent of the investigated species. For cgMLST and SNP analysis results, we found that technological sequencing artefacts could be reduced by the use of filters, and that SNP analysis was more suited than cgMLST to compare data of different contributors. Regarding the four species, a minority of Campylobacter isolate data showed the in comparison highest divergence with regard to sequence type and cgMLST analysis. We additionally compared the assembler SPAdes and SKESA for their performance on the Illumina data sets of the different species and library preparation methods and found overall similar assembly quality metrics and cgMLST statistics