987 research outputs found
Gas Storage Valuation: Price Modelling v. Optimization Methods
The existence of a financial gas market motivates the analysis of gas storage as a separate asset, using the market value context for utilization and valuation. In the recent literature, gas storage is typically analysed within a framework with a simple one-factor price dynamics that is solved to optimality. We follow a different approach, where the market is represented by a forward curve with daily granularity, the price uncertainty is represented by six factors, and where we impose a simple and intuitive storage strategy that follows from repeated maximization of the intrinsic value. Based on UK natural gas market price data, we obtain the gas storage value using our approach, and compare with results from one-factor models as well as with perfect foresight. We find that our approach captures much more of the true flexibility value than the one-factor models. Our results indicate that the appropriate framework for analyzing complex assets like gas storage is a rich representation of the price dynamics combined with a simple and intuitive decision rule.Energy; uncertainty; flexibility; exercise strategy
Dissolved gases in hydrothermal plumes from Artic vent fields
Recent discoveries of active vent fields on slow and ultraslow spreading ridges have revealed that hydrothermal activity is more common than previously assumed. In the Norwegian-Greenland Sea, two such vent fields are found; the Jan Mayen vent fields (71°N and 6°E) and Loki`s Castle (73°30′N and 8°E). Both these systems are located on the ultraslow spreading Mohns Ridge, but they differ profoundly in the geochemical fluid and gas composition. This study presents dissolved hydrogen (H2), methane (CH4) and helium isotope (3He) concentrations in the hydrothermal plume above the two vent fields. The results are based on samples collected during research cruises to the Norwegian Greenland Sea in the period 2007- 2012. The plume at the Loki's Castle rises 400 m from 2400 to 2000 m, and is characterized by considerable amounts of CH4 and H2. The rise- height is thus 50-200 m higher than observed in most hydrothermal fields in the Atlantic and Pacific Oceans. Dilution factors for the buoyant and the non-buoyant plume was calculated to be 1700 and 8900, respectively. The thermal output from Loki's Castle (1300 MW) was estimated to be comparable to that of the Rainbow field due to similar 3He input. Loki's Castle is situated between different ocean current systems, causing extensive mixing and transportation of the plume. Elevated 3He concentrations close to the seafloor indicate either deep water transport from the north or hydrothermal input from the ridge below. Comparison to the deep seawater at the East Pacific Rise, where the spreading rate is 7.5 times faster and the 3He input 6 times larger than at the AMOR, indicating a correlation between spreading rates and the magnitude of hydrothermal activity. Because of background concentrations up to 5 and 7 nM for H2 and CH4, respectively, reliable evidence for hydrothermal input requires values higher than these. Methane anomaly at a depth 2319 m indicate a possible new vent field southwest of Loki's Castle. The non-buoyant plume at the Jan Mayen vent fields (JMVF) was characterized by moderate CH4 and low H2 concentration, and rose 150 m above the Troll Wall and 200 m above the Soria Moria vent field. The dilution factor for the non-buoyant plume was estimated to be 9500 at the Troll Wall vent field. Diffuse venting occurring at the Troll Wall was characterized by the moderate CH4 and very low H2. The CH4 produced here may be of biogenic origin, produced by methanogenesis at or below the seafloor. The H2 content in the water column in 2011 was about 26 times higher than observed in any other year. This excess H2 probably originated from an eruptive event at the seafloor in the JMVF area. The results demonstrate that determination of the dissolved gas composition provides vital information on processes occurring in the surface and subsurface at Artic vent fields.Master i GeovitenskapMAMN-GEOVGEOV39
Comparison of precipitation chemistry data at a central Illinois site in 1954 and in 1977
In 1954 detailed precipitation chemistry measurements on samples from a manually operated wet-only collector provided data for the concentrations of the major ions for precipitation events. A comparison with data for the same location for 1977, collected with an automatic wet-only collector, showed that the median sulfate and nitrate concentrations were somewhat larger than in 1954 while the median calcium plus magnesium concentration was much lower. The precipitation event median pH was also much lower in 1977. Possible explanations for the present lower calcium plus magnesium concentrations and the correspondingly lower pH values are given.U. S. Department of Energy, Contract EY-1199Ope
Brd4 as a candidate protein for the recognition of histone H3 lysine 27 acetylation
Post-translational modifications (PTMs) of histone tails are associated with the regulation of transcriptional processes. Patterns of histone modifications mark regions of high or low transcriptional activity, and are recognized by reader proteins". The reader proteins are often transcription factors that recruit chromatin remodelling complexes or enzymes that add further modifications to histone tails. Genomic enhancer regions, responsible for cell- type specific activation of different genes, have been found to exhibit distinct patterns of histone modifications. Active enhancers are enriched in acetylation of histone H3 lysine 27 (H3K27ac), a mark which distinguishes active from poised and primed enhancers. In this work, we wished to find a protein which specifically recognizes this histone modification. Bromodomain- containing protein 4 (Brd4) is a transcriptional regulator that is known to be involved in the regulation of elongation by RNA polymerase II (Pol II). Brd4 has been shown to co-localize with H3K27ac at active enhancers, and was therefore chosen as a candidate for selective recognition of H3K27ac. Possible binding between the two bromodomains of Brd4 and H3K27ac was investigated by histone peptide binding assays, isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR). Brd4 bromodomain constructs containing one or both bromodomains were engineered, and proteins were expressed and used in binding assays. Strong binding between Brd4 bromodomain 1 (BD1) and a H4 peptide acetylated at four lysines (H4tetra-ac) was observed, but in contrast to a previously published study, no binding between either of the Brd4 bromodomains to H3K27ac was detected in histone peptide binding assays and ITC. Possible reasons for these discrepancies are discussed and alternative functions for Brd4 and its bromodomains at enhancer and promoter regions are suggested.Master i MolekylærbiologiMAMN-MOLMOL39
Case Note: Property Law—Outdoor Advertising Control Acts Slice City Funds into the Bunker—In re Denial of Eller Media Company’s Applications for Outdoor Advertising Device Permits in the City of Mounds View
This note first examines a brief history of the municipal development of the comprehensive plan and outdoor advertising control legislation, the federal government’s promulgation of the Highway Beautification Act, and the Minnesota Outdoor Advertising Control Act. Upon review of the background of the Eller Media case, this note highlights the opinion rendered by the Minnesota Supreme Court. An analysis of the supreme court’s interpretation in light of the outdoor advertising control acts and regulations follows, including an examination of the policies that underlie the pertinent statutes. This note concludes that based on the state of the golf course today, the supreme court’s strict interpretation of the advertising control statutes focused too narrowly on the zoning label instead of the actual land use
The Role of Eye-Movements in the Representation of Value in a Reinforcement Learning Context: A Web-Based Study
The present thesis experimentally set out to try to answer if there was a correlation between reinforcement learning and eye-movements and what the implications of such a correlation might be. An important experimental factor here was the decision to do this online, to see if it was possible to get valid and reliable results, and furthermore perhaps reach out to a more diverse group of people than a typical in-lab study would, making the results more generalizable.
38 people were recruited via the website prolific.co. The participants then performed a learning test, where they were shown two symbols on the screen, and the objective was to find the symbol with the highest value out of the pair, with three different symbol pairs. After each presentation of a pair, the participant had to choose one symbol, which were then followed by a rewarding or non-rewarding feedback. Each symbol pair had a different ratio of positive relative to negative feedback. The participants eye-movements were tracked via their web-camera, to see if they fixated more on the most rewarding symbol. The results showed that the participants reliably learned to choose the higher value symbol, comparable in validity to that of in-lab studies. We also found a statistically significant correlation between learning and fixating on the most rewarding symbol, although the quality of the eye-tracking was of too poor quality to draw any conclusions about this correlation.
The present experiment reached a diverse group of people from all over the world and proved that it is possible to perform a reinforcement learning experiment online, although the technology of eye-tracking cannot match an in-lab study. Further online research is needed in many areas to determine what type of experiments can produce valid and reliable data, which is especially relevant to the generalizability of research, and the present situation of a global pandemic which limits the in-lab approach
A tectonic analysis of the lithologic associations in the Frontier Formation, Big Horn County, Wyoming
Case Note: Property Law—Outdoor Advertising Control Acts Slice City Funds into the Bunker—In re Denial of Eller Media Company’s Applications for Outdoor Advertising Device Permits in the City of Mounds View
This note first examines a brief history of the municipal development of the comprehensive plan and outdoor advertising control legislation, the federal government’s promulgation of the Highway Beautification Act, and the Minnesota Outdoor Advertising Control Act. Upon review of the background of the Eller Media case, this note highlights the opinion rendered by the Minnesota Supreme Court. An analysis of the supreme court’s interpretation in light of the outdoor advertising control acts and regulations follows, including an examination of the policies that underlie the pertinent statutes. This note concludes that based on the state of the golf course today, the supreme court’s strict interpretation of the advertising control statutes focused too narrowly on the zoning label instead of the actual land use
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