| 1. |
- Robinson, Adam H., et al.
(författare)
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Multiscale characterisation of chimneys/pipes : Fluid escape structures within sedimentary basins
- 2021
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 106
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of seismic reflection data has identified the presence of fluid escape structures cross-cutting overburden stratigraphy within sedimentary basins globally. Seismically-imaged chimneys/pipes are considered to be possible pathways for fluid flow, which may hydraulically connect deeper strata to the seabed. The properties of fluid migration pathways through the overburden must be constrained to enable secure, long-term subsurface carbon dioxide (CO2) storage. We have investigated a site of natural active fluid escape in the North Sea, the Scanner pockmark complex, to determine the physical characteristics of focused fluid conduits, and how they control fluid flow. Here we show that a multi-scale, multi-disciplinary experimental approach is required for complete characterisation of fluid escape structures. Geophysical techniques are necessary to resolve fracture geometry and subsurface structure (e.g., multi-frequency seismics) and physical parameters of sediments (e.g., controlled source electromagnetics) across a wide range of length scales (m to km). At smaller (mm to cm) scales, sediment cores were sampled directly and their physical and chemical properties assessed using laboratory-based methods. Numerical modelling approaches bridge the resolution gap, though their validity is dependent on calibration and constraint from field and laboratory experimental data. Further, time-lapse seismic and acoustic methods capable of resolving temporal changes are key for determining fluid flux. Future optimisation of experiment resource use may be facilitated by the installation of permanent seabed infrastructure, and replacement of manual data processing with automated workflows. This study can be used to inform measurement, monitoring and verification workflows that will assist policymaking, regulation, and best practice for CO2 subsurface storage operations.
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| 2. |
- Baud, Maxime O, et al.
(författare)
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European trends in epilepsy surgery.
- 2018
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Ingår i: Neurology. - 1526-632X. ; 91:2
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Tidskriftsartikel (refereegranskat)abstract
- Resective surgery is effective in treating drug-resistant focal epilepsy, but it remains unclear whether improved diagnostics influence postsurgical outcomes. Here, we compared practice and outcomes over 2 periods 15 years apart.Sixteen European centers retrospectively identified 2 cohorts of children and adults who underwent epilepsy surgery in the period of 1997 to 1998 (n = 562) or 2012 to 2013 (n = 736). Data collected included patient (sex, age) and disease (duration, localization and diagnosis) characteristics, type of surgery, histopathology, Engel postsurgical outcome, and complications, as well as imaging and electrophysiologic tests performed for each case. Postsurgical outcome predictors were included in a multivariate logistic regression to assess the strength of date of surgery as an independent predictor.Over time, the number of operated cases per center increased from a median of 31 to 50 per 2-year period (p = 0.02). Mean disease duration at surgery decreased by 5.2 years (p < 0.001). Overall seizure freedom (Engel class 1) increased from 66.7% to 70.9% (adjusted p = 0.04), despite an increase in complex surgeries (extratemporal and/or MRI negative). Surgeries performed during the later period were 1.34 times (adjusted odds ratio; 95% confidence interval 1.02-1.77) more likely to yield a favorable outcome (Engel class I) than earlier surgeries, and improvement was more marked in extratemporal and MRI-negative temporal epilepsy. The rate of persistent neurologic complications remained stable (4.6%-5.3%, p = 0.7).Improvements in European epilepsy surgery over time are modest but significant, including higher surgical volume, shorter disease duration, and improved postsurgical seizure outcomes. Early referral for evaluation is required to continue on this encouraging trend.
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| 3. |
- Böttner, Christoph, et al.
(författare)
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Pockmarks in the Witch Ground Basin, Central North Sea
- 2019
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Ingår i: Geochemistry Geophysics Geosystems. - 1525-2027. ; 20:4, s. 1698-1719
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Tidskriftsartikel (refereegranskat)abstract
- Marine sediments host large amounts of methane (CH4), which is a potent greenhouse gas. Quantitative estimates for methane release from marine sediments are scarce, and a poorly constrained temporal variability leads to large uncertainties in methane emission scenarios. Here, we use 2-D and 3-D seismic reflection, multibeam bathymetric, geochemical, and sedimentological data to (I) map and describe pockmarks in the Witch Ground Basin (central North Sea), (II) characterize associated sedimentological and fluid migration structures, and (III) analyze the related methane release. More than 1,500 pockmarks of two distinct morphological classes spread over an area of 225 km(2). The two classes form independently from another and are corresponding to at least two different sources of fluids. Class 1 pockmarks are large in size (> 6 m deep, > 250 m long, and > 75 m wide), show active venting, and are located above vertical fluid conduits that hydraulically connect the seafloor with deep methane sources. Class 2 pockmarks, which comprise 99.5% of all pockmarks, are smaller (0.9-3.1 m deep, 26-140 m long, and 14-57 m wide) and are limited to the soft, fine-grained sediments of the Witch Ground Formation and possibly sourced by compaction-related dewatering. Buried pockmarks within the Witch Ground Formation document distinct phases of pockmark formation, likely triggered by external forces related to environmental changes after deglaciation. Thus, greenhouse gas emissions from pockmark fields cannot be based on pockmark numbers and present-day fluxes but require an analysis of the pockmark forming processes through geological time. Plain Language Summary Marine sediments host large amounts of methane (CH4), which is a potent greenhouse gas. The amount of methane released into the atmosphere is, however, largely unknown making it difficult to implement this methane source in climate models. Here we use geophysical, geochemical, and sedimentological data to map the distribution of fluid escape structures in the central North Sea. More than 1,500 pockmarks, which are circular to semicircular depressions of the seafloor, indicate fluid flow from the subsurface. There are two distinct morphological classes of pockmarks corresponding to at least two different fluid sources. Class 1 pockmarks are large, show active venting, and are located above vertical fluid conduits in the subsurface, which feed fluids from deeper strata. Class 2 pockmarks, which comprise 99.5% of all pockmarks, are smaller and limited to the soft sediments directly below the seafloor. Older pockmarks in the subsurface document distinct phases of pockmark formation, likely triggered by external forces after the retreat of ice in the North Sea. The amount of methane released from natural geological sources based on pockmark numbers may be wrong as these do not take into account the origin and composition of released fluids.
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| 4. |
- Böttner, Christoph, et al.
(författare)
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Pockmarks in the Witch Ground Basin, Central North Sea
- 2019
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Ingår i: Geochemistry Geophysics Geosystems. - : American Geophysical Union (AGU). - 1525-2027. ; 20:4, s. 1698-1719
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Tidskriftsartikel (refereegranskat)abstract
- Marine sediments host large amounts of methane (CH4), which is a potent greenhouse gas. Quantitative estimates for methane release from marine sediments are scarce, and a poorly constrained temporal variability leads to large uncertainties in methane emission scenarios. Here, we use 2-D and 3-D seismic reflection, multibeam bathymetric, geochemical, and sedimentological data to (I) map and describe pockmarks in the Witch Ground Basin (central North Sea), (II) characterize associated sedimentological and fluid migration structures, and (III) analyze the related methane release. More than 1,500 pockmarks of two distinct morphological classes spread over an area of 225 km2. The two classes form independently from another and are corresponding to at least two different sources of fluids. Class 1 pockmarks are large in size (>6 m deep, >250 m long, and >75 m wide), show active venting, and are located above vertical fluid conduits that hydraulically connect the seafloor with deep methane sources. Class 2 pockmarks, which comprise 99.5% of all pockmarks, are smaller (0.9–3.1 m deep, 26–140 m long, and 14–57 m wide) and are limited to the soft, fine-grained sediments of the Witch Ground Formation and possibly sourced by compaction-related dewatering. Buried pockmarks within the Witch Ground Formation document distinct phases of pockmark formation, likely triggered by external forces related to environmental changes after deglaciation. Thus, greenhouse gas emissions from pockmark fields cannot be based on pockmark numbers and present-day fluxes but require an analysis of the pockmark forming processes through geological time.
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| 5. |
- Elger, Christian, et al.
(författare)
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Pooled efficacy and safety of eslicarbazepine acetate as add-on treatment in patients with focal-onset seizures: Data from four double-blind placebo-controlled pivotal phase III clinical studies
- 2017
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Ingår i: CNS Neuroscience and Therapeutics. - : Wiley. - 1755-5930 .- 1755-5949. ; 23, s. 961-972
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Authors. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd. Purpose: Pooled evaluation of the key efficacy and safety profile of eslicarbazepine acetate (ESL) added-on to stable antiepileptic therapy in adults with focal-onset seizures. Methods: Data from 1703 patients enrolled in four phase III double-blind, randomized, placebo-controlled studies were pooled and analyzed. Following a 2week titration period, ESL was administered at 400mg, 800mg, and 1200mg once-daily doses for 12weeks (maintenance period). Pooled efficacy variable was standardized (/4weeks) seizure frequency (SSF) analyzed over the maintenance period as reduction in absolute and relative SSF and proportion of responders (≥50% reduction in SSF). Pooled safety was analyzed by means of adverse events and clinical laboratory assessments. Results: SSF was significantly reduced with ESL 800mg (P<0.0001) and 1200mg (P<0.0001) compared to placebo. Median relative reduction in SSF was 33.4% for ESL 800mg and 37.8% for 1200mg (placebo: 17.6%), and responder rate was 33.8% and 43.1% (placebo: 22.2%). ESL was more efficacious than placebo regardless of gender, geographical region, epilepsy duration, age at time of diagnosis, seizure type, and type of concomitant antiepileptic drugs (AED). Incidence of adverse events (AEs) and AEs leading to discontinuation was dose dependent. Most common AEs (>10% patients) were dizziness, somnolence, and nausea. The incidence of treatment-emergent AEs (dizziness, somnolence, ataxia, vomiting, and nausea) was lower in patients who began taking ESL 400mg (followed by 400mg increments to 800 or 1200mg) than in those who began taking ESL 600mg or 800mg. Conclusions: Once-daily ESL 800mg and 1200mg showed consistent results across all efficacy and safety endpoints, independent of study population characteristics and type of concomitant AEDs. Treatment initiated with ESL 400mg followed by 400mg increments to 800 or 1200mg provides optimal balance of efficacy and tolerability.
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| 6. |
- Elger, Judith, et al.
(författare)
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Core‐log‐seismic integration in metamorphic rocks and its implication for the regional geology : A case study for the ICDP drilling project COSC‐1, Sweden
- 2021
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Ingår i: Geochemistry Geophysics Geosystems. - : American Geophysical Union (AGU). - 1525-2027. ; 22:3
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Tidskriftsartikel (refereegranskat)abstract
- Continental collision causes deformation in the crust along shear zones. However, the physical and chemical conditions at which these zones operate and the deformation processes that enable up to hundreds of km of tectonic transport are still unclear because of the depth at which they occur and the challenges in imaging them. Ancient exhumed collision zones allow us to investigate these processes much better, for example at the COSC‐1 borehole in the central Scandinavian Caledonides. This study combines data from the COSC‐1 borehole with different seismic measurements to provide constraints on the spatial lithological and textural configuration of the Seve Nappe Complex. This is one of the few studies that shows that core‐log‐seismic integration in metamorphic rocks allows to identify the spatial distribution of major lithological units. Especially gamma ray logs in combination with density data are powerful tools to distinguish between mafic and felsic lithologies in log‐core correlation. Our results indicate that reflections along the borehole are primarily caused by compositional rather than textural changes. Reflections in the Seve Nappe Complex are not as distinct as in greater depths but continuous and several of them can be linked to magmatic intrusions, which have been metamorphically overprinted. Their setting indicates that the Seve Nappe Complex consists of the remnants of a volcanic continental margin. Our results suggest that ductile‐deformed middle crustal reflectivity is primarily a function of pre‐orogenic lithological variations which has to be considered when deciphering mountain building processes.Plain Language SummaryAreas where continents collide experience different kind of deformation. However, these processes and the conditions at which they take place are difficult to study because of the great depth at which they occur. Former collision zones that are closer to the surface these days allow the investigation of these processes much better, for example at the COSC‐1 borehole in the central Scandinavian Caledonides. The challenge remains to image the remnant of these processes in high detail but at the same time over a large area. This study combines data from the COSC‐1 borehole with different geophysical measurements to better understand the lithology and structure of the Seve Nappe Complex. We show that the combination of these data allows us to distinguish between rocks from mafic and sedimentary origin. Our results indicate that the geophysical data along the borehole image the change of the composition of the rocks which probably originates from magmatic intrusions and have been overprinted by geological processes, rather than from fracture zones.
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| 7. |
- Feldwisch-Drentrup, Hinnerk, et al.
(författare)
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Identification of preseizure states in epilepsy: a data-driven approach for multichannel EEG recordings
- 2011
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Ingår i: Frontiers in Computational Neuroscience. - : Frontiers Research Foundation. - 1662-5188. ; 5:32
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Tidskriftsartikel (refereegranskat)abstract
- The retrospective identification of preseizure states usually bases on a time-resolved characterization of dynamical aspects of multichannel neurophysiologic recordings that can be assessed with measures from linear or non-linear time series analysis. This approach renders time profiles of a characterizing measure - so-called measure profiles - for different recording sites or combinations thereof. Various downstream evaluation techniques have been proposed to single out measure profiles that carry potential information about preseizure states. These techniques, however, rely on assumptions about seizure precursor dynamics that might not be generally valid or face the statistical problem of multiple testing. Addressing these issues, we have developed a method to preselect measure profiles that carry potential information about preseizure states, and to identify brain regions associated with seizure precursor dynamics. Our data-driven method is based on the ratio S of the global to local temporal variance of measure profiles. We evaluated its suitability by retrospectively analyzing long-lasting multichannel intracranial EEG recordings from 18 patients that included 133 focal onset seizures, using a bivariate measure for the strength of interactions. In 17/18 patients, we observed S to be significantly correlated with the predictive performance of measure profiles assessed retrospectively by means of receiver-operating-characteristic statistics. Predictive performance was higher for measure profiles preselected with S than for a manual selection using information about onset and spread of seizures. Across patients, highest predictive performance was not restricted to recordings from focal areas, thus supporting the notion of an extended epileptic network in which even distant brain regions contribute to seizure generation. We expect our method to provide further insight into the complex spatial and temporal aspects of the seizure generating process.
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| 8. |
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| 9. |
- Fisher, Robert S., et al.
(författare)
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ILAE official report : a practical clinical definition of epilepsy
- 2014
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Ingår i: Epilepsia. - : Wiley-Blackwell. - 0013-9580 .- 1528-1167. ; 55:4, s. 475-482
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Tidskriftsartikel (refereegranskat)abstract
- Epilepsy was defined conceptually in 2005 as a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures. This definition is usually practically applied as having two unprovoked seizures >24h apart. The International League Against Epilepsy (ILAE) accepted recommendations of a task force altering the practical definition for special circumstances that do not meet the two unprovoked seizures criteria. The task force proposed that epilepsy be considered to be a disease of the brain defined by any of the following conditions: (1) At least two unprovoked (or reflex) seizures occurring >24h apart; (2) one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10years; (3) diagnosis of an epilepsy syndrome. Epilepsy is considered to be resolved for individuals who either had an age-dependent epilepsy syndrome but are now past the applicable age or who have remained seizure-free for the last 10years and off antiseizure medicines for at least the last 5years. "Resolved" is not necessarily identical to the conventional view of "remission or "cure." Different practical definitions may be formed and used for various specific purposes. This revised definition of epilepsy brings the term in concordance with common use. A PowerPoint slide summarizing this article is available for download in the Supporting Information section.
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| 10. |
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