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Characterizing and monitoring the highly variable near-surface underneath urban areas is crucial for understanding phenomena such as resource distribution and storage potential, changes in hydrological systems, and seismic hazard at the sub-kilometer scale. Our current understanding of the urban subsurface is limited by our ability to image its structure and temporal variations at high resolution using classical geophysical approaches. Distributed Acoustic Sensing (DAS) deployed on unused telecommunication fiber-optic cables (dark fibers) is an attractive alternative to classic seismological studies in urban areas, as it enables continuous recording of the seismic wavefield across long distances (10’s of km) at high spatial (~1 m) and temporal (down to seconds) resolution across a broad frequency range (mHz to kHz). Here, we explore the potential and challenges of using DAS deployed on dark fiber networks for characterizing and monitoring the near-surface beneath urban areas. We will discuss dark fiber experiments conducted in a variety of settings, including several km-long profiles crossing agricultural areas and densely populated centers in California, and experiments conducted within the city of Potsdam (Germany). We evaluate the usability of anthropogenic signals as passive sources for near-surface imaging and monitoring, as well as the potential for active source seismic imaging in complex noise environments. Challenges associated with poorly documented deployment and coupling conditions of dark fiber networks and the large data volumes generated in these studies will also be discussed. Ultimately, we aim at providing insights into the challenges and opportunities of using dark fiber DAS for understanding the urban subsurface., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

HBV-DNA levels are low or even undetectable in the majority HDV-infected patients. The impact of PEG-IFNα on HBV-DNA kinetics in HDV-infected patients has not been studied in detail. We analysed data of a prospective treatment trial where 120 HDV-RNA–positive patients were randomized to receive PEG-IFNα-2a plus tenofovir-disoproxil-fumarate (PEG-IFNα/TDF, n = 59) or placebo (PEG-IFNα/PBO; n = 61) for 96 weeks. At week 96, HBV-DNA was still quantifiable in 71% of PEG-IFNα/PBO-treated patients but also in 76% of PEG-IFNα/TDF-treated patients, despite low HBV-DNA baseline values. Surprisingly, a transient HBV-DNA increase between weeks 12 and 36 was observed in 12 in PEG-IFNα/TDF-treated and 12 PEG-IFNα/PBO-treated patients. This increase was positively associated with HBsAg loss [(P = 0.049, odds ratio (OR) 5.1] and HDV-RNA suppression (P = 0.007, OR 4.1) at week 96. Biochemical markers of cell death (M30 and ALT) were higher during the HBV-DNA peak but no distinct systemic immune pattern could be observed by screening 91 soluble inflammatory markers. In conclusion, an early increase in HBV-DNA during PEG-IFNα-2a therapy occurred in more than 20% of patients, even in TDF-treated patients. This transient HBV-DNA rise may indicate PEG-IFNα–induced cell death and lead to long-term HDV-RNA suppression and HBsAg loss. © 2020 John Wiley & Sons Ltd

The role of low levels of HDV-RNA during and after interferon therapy of hepatitis D is unknown. We re-analysed HDV RNA in 372 samples collected in the HIDIT-2 trial (Wedemeyer et al, Lancet Infectious Diseases 2019) with the Robogene assay (RA; Jena Analytics). Data were compared with the previously reported in-house assay (IA). We detected HDV-RNA in one-third of samples previously classified as undetectable using the highly sensitive RA. Low HDV viraemia detectable at week 48 or week 96 was associated with a high risk for post-treatment relapse, defined as HDV RNA positivity in both assays at week 120. HDV RNA relapses occurred in 10/15 (67%) patients with detectable low HDV RNA at week 48 and in 10/13 (77%) patients with low viraemia samples at week 96. In contrast, the post-treatment relapse rate was lower in patients with undetectable HDV RNA in both assays during treatment. © 2020 The Authors. Liver International published by John Wiley & Sons Ltd

The authors gratefully acknowledge the funding for the Ketzin project received from the European Commission (6th and 7th Framework Program), two German ministries—the Federal Ministry of Economics and Technology and the Federal Ministry of Education and Research— and industry since 2004. The most recent R&D activities were funded within the project COMPLETE by the Federal Ministry of Education and Research. Further funding was received from VGS, RWE, Vattenfall, Statoil, OMV and the Norwegian CLIMIT programme.

Background: Hepatitis D is the most severe form of chronic viral hepatitis. Treatment guidelines recommend 1 year of peginterferon alfa, which is effective in 25–30% of patients only. Whether prolonged therapy with peginterferon alfa-2a for 96 weeks and combination therapy with tenofovir disoproxil fumarate (TDF) would increase hepatitis D virus (HDV) RNA suppression is unknown. We aimed to explore whether prolonged treatment of HDV with 96 weeks of peginterferon would increase HDV RNA response rates and reduces post-treatment relapses. Methods: We did two parallel, investigator-initiated, multicentre, double-blind randomised, controlled trials at 14 study sites in Germany, Greece, Romania, and Turkey. Patients with chronic HDV infection and compensated liver disease who were aged 18 years or older were eligible for inclusion. All patients were HBsAg positive for at least 7 months, anti-HDV positive for at least 3 months, and HDV-RNA positive at the local laboratory at the screening visit. Patients were ineligible if alanine aminotransferase levels were higher than ten times above the upper limit of normal and if platelet counts were lower than 90 000 per μL, or if they had received interferon therapy or treatment with a nucleoside and nucleotide analogue within the preceding 6 months. Patients were randomly assigned by blinded stratified block randomisation (1:1) to receive 180 μg of peginterferon alfa-2a weekly plus either TDF (300 mg once daily) or placebo for 96 weeks. The primary endpoint was the percentage of patients with undetectable HDV RNA at the end of treatment assessed by intention to treat. The trials are registered as NCT00932971 and NCT01088659. Findings: Between June 24, 2009, and Feb 28, 2011, we randomly assigned 59 HDV RNA-positive patients to receive peginterferon alfa-2a plus TDF and 61 to receive peginterferon alfa-2a plus placebo, including 48 (40%) patients with cirrhosis to the two treatment groups (23 in the peginterferon alfa-2a plus TDF group and 25 in the peginterferon alfa-2a plus placebo group). The primary endpoint was achieved in 28 (48%) of 59 patients in the peginterferon alfa-2a plus TDF group and in 20 (33%) of 61 patients in the peginterferon alfa-2a plus placebo group (odds ratio 1·84, 95% CI 0·86–3·91, p=0·12). We recorded 944 adverse events (459 in the peginterferon alfa-2a plus TDF group and 485 in the peginterferon alfa-2a plus placebo group). The most common adverse events were haematological, behavioural (eg, fatigue), musculoskeletal, influenza-like syndromes, and psychiatric complaints. Interpretation: Addition of TDF resulted in no significant improvement in HDV RNA response rates at the end of treatment. These findings highlight that alternative treatment options are needed for hepatitis D. Funding: The HepNet Study-House (a project of the German Liver Foundation founded by the German Liver Foundation, the German Ministry for Education and Research, and the German Center for Infectious Disease Research), Hoffmann-La Roche, and Gilead Sciences. © 2019 Elsevier Ltd

Seismic methods are a cornerstone for the exploration of the subsurface. In comparison to seismic surveys at the surface, downhole measurements can help to gather more detailed information about rock properties as well as potential fluid pathways within geothermal reservoirs. Temperatures within geothermal wells, especially in magmatic environments, however, often exceed the temperature limitation of conventional seismic sensors. One way to overcome the lack of seismic downhole data for geothermal exploration is the application of the novel fiber optic distributed acoustic sensing (DAS) technology. For DAS, an optical fiber is used as seismic sensor. Lowering a fiber optic cable into a well, dynamic vibrations can be measured along the entire fiber with a high spatial resolution. As all electronics can be operated at the surface, the temperature tolerance for the measurement set-up, is defined by the operating temperature range of the fiber optic cable. Special optical fibers can be operated at temperatures up to several hundred degrees centigrade, therefore, closing the gap between the operating temperature limit of conventional seismic sensors and the requirements for a downhole application within geothermal wells. In this paper, the requirements for an Installation of a fiber optic cable within a high-temperature well will be discussed, DAS data will be compared to conventional geophone data, and the benefit of applying the DAS technology for seismic exploration within the framework of the Iceland Deep Drilling Project (IDDP) will be outlined.

Preface 2012The General Assembly of the European Geosciences Union(EGU) is the largest conference in Europe dedicated to geosciences. Approximately 11,000 participants were registered in 2012, with the conference being hosted for the 8th time in Vienna, Austria, from 22 to 27 April. Within the EGU the Division Energy, Resources & the Environment (ERE) was hosting four sessions dedicated to the geological storage of CO2. From more than 118 papers presented at the conference, 15 were selected for publication in this special issue of the International Journal of Greenhouse Gas Control. All articles are fully peer-reviewed and cover various important aspects of CO2storage, demonstrating the diversity of disciplines required for the planning of safe and feasible long-term underground storage of CO2.