Carbon Capture and Storage and the Marine Environment: Impact assessment and assurance monitoring

Underground storage of CO2 as part of Carbon Capture and Storage (CCS) provides an option for significant reduction of CO2 emissions from fossil fuel power generation and other industrial processes as well as facilitating direct air capture. Although CCS will mitigate climate change, international regulations and societal expectations require that storage integrity is assured and environmental issues of deployment are considered, in particular related to the unplanned release of CO2. Globally many storage sites are located offshore within continental shelves, necessitating both a marine environmental impact assessment and an appropriate offshore monitoring strategy coupled with appropriate communication to enhance public understanding. This thesis by papers contains a body of work addressing both impact and monitoring challenges, primarily mediated using modelling approaches but also describing a novel real-world CO2 release experiment. The experiment revealed the previously unconsidered complexity of CO2 flow through and reactivity within sediments and behaviour in the water column. This work established the challenges associated with monitoring and detection informing further research programmes focused on increasing the technology readiness levels of sensors and developing monitoring strategies. As a result of the body of work presented here it is possible to constrain potential impacts, relative to leakage rates and conclude that only large-scale catastrophic leaks would have the capacity to inflict significant environmental damage. This work also identifies a potentially cost efficient and highly sensitive detection/assurance methodology, based on an understanding of leakage dynamics and natural variability of the marine system

Hashing it Out: Blockchain as a Solution for Medicare Improper Payments

Part I highlights the inadequacies and inefficiencies of our Medicare payment system, focusing on the initiatives currently in place and the susceptibilities that persist. Part II offers a broad overview of the development, importance, features, and collateral technologies surrounding blockchain. Part III posits that Congress and HHS, through its various subsidiary agencies, should work in tandem with private stakeholders to create and/or implement a blockchain-based infrastructure to facilitate federal healthcare payments and support future growth of quality-based initiatives. This Note concludes with a recommendation for future agency research focusing on the viability and cost efficiency of a blockchain solution

Extending the late holocene tephrochronology of the central Kenai Peninsula, Alaska

Tephrochronology, the reconstruction of past volcanic ash deposition, provides a valuable method for dating sediments and determining long-term volcanic history. Tephra layers are highly numerous in Alaska, but knowledge of their occurrence and distribution is incomplete. This study expands the regional tephrochronology for the Kenai Peninsula of southcentral Alaska by investigating the tephrostratigraphy of two peatland sites. We located seven visible tephras and seven microtephras and investigated the particle size and geochemistry of the visible tephras. Radiocarbon dates were used to estimate the timescale of each core. Geochemical comparison showed that the visible tephras originated from late Holocene eruptions of Augustine, Crater Peak-Mt. Spurr, and Hayes volcanoes. Some of the tephras had been documented previously, and these new findings expand their known range. Others represent eruptions not previously reported, including a Crater Peak-Mt. Spurr eruption around 430 cal. BP. The results provide new tephra data for the region, illustrate the spatial heterogeneity of tephra deposition, and show the potential of microtephras for expanding the regional tephra record

Guidance, flight mechanics and trajectory optimization. Volume 6 - The N-body problem and special perturbation techniques

Analytical formulations and numerical integration methods for many body problem and special perturbative technique

Disturbance and succession in early to mid-holocene northern english forests:Palaeoecological evidence for disturbance of woodland ecosystems by mesolithic hunter-gatherers

Forest succession can be monitored in the present, modelled for the future, but also reconstructed in the past on the records of forest history, including through the use of palaeo-ecological techniques. Longer-term records from pollen data can show changes over centennial and millennial timescales that are impacted by climate, migration or soil development. Having knowledge of previous phases of post-disturbance seral stages of woodland regeneration however, as after fire, can provide insights regarding successional process and function over short-term decadal timescales. The aim of this paper is to test the high-resolution pollen record as a source of new insights into processes of succession, assisted by the supplementary data of microscopic charcoal analyses. On short-term timescales, multiple phases of forest disturbance and then recovery have been identified in early to mid-Holocene peat records in northern England, many from the uplands but also from lowland areas. We identify and describe a typology of recovery patterns, including the composition and rate of recovery, and then test the processes and factors that impacted on different seral trajectories, concentrating on fire disturbance which might have had a natural origin, or might have been caused by pre-agricultural Mesolithic hunter-gatherers. Factors considered include the spatial location and intensity of the fire event, the duration of the disturbance phase, the structure and dynamics of the successional regeneration vegetation communities and the pre-disturbance tree cover. Data from examples of fire disturbance of woodland have been examined from both upland and lowland sites in northern England and indicate that they had different successional pathways after disturbance. Fire disturbances in the denser lowland forests were mostly single burn events followed by natural successions and regeneration to forest, whereas fire disturbances in the upland woods usually showed continued or repetitive fire pressure after the initial burning, arresting succession so that vegetation was maintained in a shrub phase, often dominated by Corylus, for an extended period of time until disturbance ceased. This creation of a kind of prolonged, almost plagioclimax, ‘fire-coppice’ hazel stage suggests controlled rather than natural successional pathways, and strongly suggests that Mesolithic foragers were the fire starters in the upland English woodlands where hazel was naturally common and could be maintained in abundance in later-stage successions, along with other edible plants, for human use. All post-fire seral stages would have been attractive to game animals, providing a reliable food source that would have been of great benefit to hunter-gatherer populations