Using digital field notebooks in geoscientific learning in polar environments

Postponed access: the file will be available after 2022-08-21The emergence of digital tools, including tablets with a multitude of built-in sensors, allows gathering many geological observations digitally and in a geo-referenced context. This is particularly important in the polar environments where (1) limited time is available at each outcrop due to harsh weather conditions, and (2) outcrops are rarely re-visited due to the high economic and environmental cost of accessing the localities and the short field season. In an educational development project, we explored the use of digital field notebooks in student groups of 3–4 persons during five geological field campaigns in the Arctic archipelago of Svalbard. The field campaigns formed part of the Bachelor and Master/PhD courses at the University Centre in Svalbard in Longyearbyen at 78°N. The digital field notebooks comprise field-proofed tablets with relevant applications, notably FieldMove. Questionnaires and analyses of students’ FieldMove projects provided data on student experience of using digital field notebooks, and insight into what students used the digital notebooks for, the notebooks’ functionality and best practices. We found that electronic and geo-referenced note- and photo-taking was by far the dominant function of the digital field notebooks. In addition, some student groups collected significant amounts of structural data using the built-in sensors. Graduate students found the ability to conduct large-scale field mapping and directly display it within the digital field notebook particularly useful. Our study suggests that the digital field notebooks add value to field-based education in polar environments.acceptedVersio

In situ triaxial testing to determine fracture permeability and aperture distribution for CO2 sequestration in Svalbard, Norway

On Svalbard, Arctic Norway, an unconventional silicidastic reservoir, relying on (micro)fractures for enhanced fluid flow in a low-permeable system, is investigated as a potential CO2 sequestration site. The fractures' properties at depth are, however, poorly understood. High resolution X-ray computed tomography (micro-CT) imaging allows one to visualize such geomaterials at reservoir conditions. We investigated reservoir samples from the De Geerdalen Formation on Svalbard to understand the influence of fracture closure on the reservoir fluid flow behavior. Small rock plugs were brought to reservoir conditions, while permeability was measured through them during micro-CT imaging. Local fracture apertures were quantified down to a few micrometers wide. The permeability measurements were complemented with fracture permeability simulations based on the obtained micro-CT images. The relationship between fracture permeability and the imposed confining pressure was determined and linked to the fracture apertures. The investigated fractures closed due to the increased confining pressure, with apertures reducing to approximately 40% of their original size as the confining pressure increased from 1 to 10 MPa. This coincides with a permeability drop of more than 90%. Despite their closure, fluid flow is still controlled by the fractures at pressure conditions similar to those at the proposed storage depth of 800-1000 m

West Spitsbergen fold and thrust belt: A digital educational data package for teaching structural geology

The discipline of structural geology is taking an advantage of compiling observations from multiple field sites to comprehend the bigger picture and constrain the region's geological evolution. In this study we demonstrate how integration of a range of geospatial digital data sets that relate to the Paleogene fault and thrust belt exposed in the high Arctic Archipelago of Svalbard, is used in teaching in bachelor-level courses at the University Centre in Svalbard. This event led to the formation of the West Spitsbergen Fold and Thrust Belt and its associated foreland basin, the Central Spitsbergen Basin. Our digital educational data package builds on published literature from the past four decades augmented with recently acquired high-resolution digital outcrop models, and 360° imagery. All data are available as georeferenced data containers and included in a single geodatabase, freely available for educators and geoscientists around the world to complement their research and fieldwork with course components from Svalbard.publishedVersio

Antikaon Production in Proton-Nucleus Reactions and the K−K^- properties in nuclear matter

We calculate the momentum-dependent potentials for $K^+$ and $K^-$ mesons in a dispersion approach at nuclear density $\rho_0$ using the information from the vacuum $K^+ N$ and $K^- N$ scattering amplitudes, however, leaving out the resonance contributions for the in-medium analysis. Whereas the $K^+$ potential is found to be repulsive ($\approx$ + 30 MeV) and to show only a moderate momentum dependence, the $K^-$ selfenergy at normal nuclear matter density turns out to be $\approx$ - 200 MeV at zero momentum in line with kaon atomic data, however, decreases rapidly in magnitude for higher momenta. The antikaon production in p + A reactions is calculated within a coupled transport approach and compared to the data at KEK including different assumptions for the antikaon potentials. Furthermore, detailed predictions are made for $p + ^{12}C$ and $p + ^{207}Pb$ reactions at 2.5 GeV in order to determine the momentum dependent antikaon potential experimentally.Comment: 27 pages, LaTeX, including 14 ps-figures, UGI-98-1

The interaction of slow J/psi and psi' with nucleons

The interaction of the charmonium resonances J/psi and psi' with nucleons at low energies is considered using the multipole expansion and low-energy theorems in QCD. A lower bound is established for the relevant gluonic operator average over the nucleon. As a result we find the discussed interaction to be significantly stronger than previously estimated in the literature. In particular we conclude that the cross section of the J/psi - nucleon elastic scattering at the threshold is very likely to exceed 17 millibarn and that existence of bound states of the J/psi in light nuclei is possible. For the psi' resonance we estimate even larger elastic scattering cross section and also a very large cross section of the process psi'+N -> psi+N giving rise to the decay width of tens of MeV for the psi' resonance in heavy nuclei.Comment: 7 page

Cenozoic uplift and erosion of the Norwegian Barents Shelf – A review

Uplift and erosion are complex phenomena in terms of their governing processes, precise timing and exact magnitude. The intricate relationship between different geodynamic processes leading to uplift may increase uncertainties in estimating spatial and temporal patterns. Sediment distribution from uplifted (and eroded) topography and the corresponding paleoenvironmental reconstructions require reliable constrains. The Barents Shelf provides a unique arena to study uplift and erosion due to extensive seismic and well data attributed to high petroleum activity. This particular interest has led to a voluminous literature about this topic over the last three decades. Here, we present the current status of the Cenozoic uplift and erosion on the Norwegian Barents Shelf by reviewing the key terminology, its tectonic history and paleoenvironment, methods in quantifying uplift and erosion, as well as timing and possible mechanisms. Our new erosion maps show an increase in net erosion to the north and northeast that represents key underlying concepts, including tectonic (compression, rift-flank uplift, thermo-mechanical coupling, mantle dynamics, flexural/isostatic response) as well as magmatic and glacial processes. We have integrated pre-glacial and glacial net erosion using the mass balance method and added our results from sonic velocity, interval velocity and sandstone diagenesis methods to the new maps. This review shows that discrepancies of net erosion estimates from different methods are on the order of 500 m. Finally, we identify research gaps for future studies, with implications for the Barents Shelf and other uplifted basins worldwide

Metabolic network reconstruction and genome-scale model of butanol-producing strain Clostridium beijerinckii NCIMB 8052

<p>Abstract</p> <p>Background</p> <p>Solventogenic clostridia offer a sustainable alternative to petroleum-based production of butanol--an important chemical feedstock and potential fuel additive or replacement. <it>C. beijerinckii </it>is an attractive microorganism for strain design to improve butanol production because it (i) naturally produces the highest recorded butanol concentrations as a byproduct of fermentation; and (ii) can co-ferment pentose and hexose sugars (the primary products from lignocellulosic hydrolysis). Interrogating <it>C. beijerinckii </it>metabolism from a systems viewpoint using constraint-based modeling allows for simulation of the global effect of genetic modifications.</p> <p>Results</p> <p>We present the first genome-scale metabolic model (<it>i</it>CM925) for <it>C. beijerinckii</it>, containing 925 genes, 938 reactions, and 881 metabolites. To build the model we employed a semi-automated procedure that integrated genome annotation information from KEGG, BioCyc, and The SEED, and utilized computational algorithms with manual curation to improve model completeness. Interestingly, we found only a 34% overlap in reactions collected from the three databases--highlighting the importance of evaluating the predictive accuracy of the resulting genome-scale model. To validate <it>i</it>CM925, we conducted fermentation experiments using the NCIMB 8052 strain, and evaluated the ability of the model to simulate measured substrate uptake and product production rates. Experimentally observed fermentation profiles were found to lie within the solution space of the model; however, under an optimal growth objective, additional constraints were needed to reproduce the observed profiles--suggesting the existence of selective pressures other than optimal growth. Notably, a significantly enriched fraction of actively utilized reactions in simulations--constrained to reflect experimental rates--originated from the set of reactions that overlapped between all three databases (<it>P </it>= 3.52 × 10^-9, Fisher's exact test). Inhibition of the hydrogenase reaction was found to have a strong effect on butanol formation--as experimentally observed.</p> <p>Conclusions</p> <p>Microbial production of butanol by <it>C. beijerinckii </it>offers a promising, sustainable, method for generation of this important chemical and potential biofuel. <it>i</it>CM925 is a predictive model that can accurately reproduce physiological behavior and provide insight into the underlying mechanisms of microbial butanol production. As such, the model will be instrumental in efforts to better understand, and metabolically engineer, this microorganism for improved butanol production.</p

Discovery of shale gas in organic rich Jurassic successions, Adventdalen, Central Spitsbergen, Norway

Thermogenic dry gas flowed from Jurassic sections in the DH5R research well drilled onshore in Adventdalen, central Spitsbergen, Arctic Norway. The DH5R gas originates from the organic-rich units of the mudstone-dominated Middle Jurassic to Lower Cretaceous Agardhfjellet Formation, which is the onshore equivalent to the Fuglen Formation and the prolific oil and gas generating Hekkingen Formation in the southern Barents Shelf. Low-permeable, low-porosity sandstones from the Upper Triassic De Geerdalen Formation of the neighbouring DH4 well were oil-stained and gas was also collected from this interval. Gas from the two stratigraphic intervals have different compositions; the gas from the Agardhfjellet Formation is drier and isotopically heavier than the gas from the Upper Triassic succession. Both gases originated from source rocks of maturity near the end of the oil window (1.1 < Ro < 1.4% Ro). Maceral analyses of the Agardhfjellet Formation indicate that the more silty parts contain a high percentage of vitrinite-rich type III kerogen, whereas the clay-dominated parts are rich in liptinitic type II kerogen. The Agardhfjellet Formation has therefore the potential to generate both oil and gas. Several simulations based on pressure data and flow rates from the DH5R well were run to evaluate if the gas accumulation in the Agardhfjellet Formation is producible, i.e., can it be commercial shale gas. The models demonstrate how changes in the drainage area size and form, well types (vertical versus horizontal), number and length of induced fractures and thickness of the Agardhfjellet Formation affect gas production rates and producible volumes. Despite uncertainties in the input data, simulations indicate that the shale gas accumulation characterised in Adventdalen is producible. This gas can have major environmental benefits as an alternative for local power generation compared to coal.publishedVersio

Upregulation of VEGF and FGF2 in Normal Rat Brain after Experimental Intraoperative Radiation Therapy

The expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF)2 in the irradiated brain was examined to test how a single high dose radiation, similar to that used for intraoperative radiation therapy given to the normal cerebrum, can affect the vascular endothelium. After a burr hole trephination in the rat skull, the cerebral hemisphere was exposed to a single 10 Gy dose of gamma rays, and the radiation effect was assessed at 1, 2, 4, 6, and 8 weeks after irradiation. His-tological changes, such as reactive gliosis, inflammation, vascular proliferation and necrosis, were correlated with the duration after irradiation. Significant VEGF and FGF2 expression in the 2- and 8-week were detected by enzyme-linked immunosorbent assay quantification in the radiation group. Immunohistochemical study for VEGF was done and the number of positive cells gradually increased over time, compared with the sham operation group. In conclusion, the radiation injuries consisted of radiation necrosis associated with the expression of VEGF and FGF2. These findings indicate that VEGF and FGF2 may play a role in the radiation injuries after intraoperative single high-dose irradiation

Energy Transfer Rate in Double-Layer Graphene Systems: Linear Regime

We investigate theoretically the energy transfer phenomenon in a double-layer graphene (DLG) system in which two layers are coupled due to the Coulomb interlayer interaction without appreciable interlayer tunneling. We use the balance equation approach and the dynamic and temperature dependent random phase approximation (RPA) screening function in our calculations to obtain the rates of energy transfer between two graphene layers at different layer electron temperatures, densities and interlayer spacings and compare the results with those calculated for the conventional double-layer two-dimensional electron gas (2DEG) systems. In addition, we study the effect of changing substrate dielectric constant on the rate of energy transfer. The general behavior of the energy transfer rate in the DLG is qualitatively similar to that obtained in the double-layer 2DEG but quantitatively its DLG values are an order of magnitude greater. Also, at large electron temperature differences between two layers, the electron density dependence of the energy transfer for the DLG system is significantly different from that found for the double-layer 2DEG system, particularly in case of unequal layer electron densities.Comment: 12 pages,4 figure