Experimental study of density fluctuations in the STOR-M tokamak by small-angle microwave scattering

Density fluctuations in high temperature fusion plasmas have been a central challenge to the development of fusion power. They are the cause of excessive anomalous losses from the plasma and are still not fully understood. A microwave scattering experiment is performed on the Saskatchewan Torus-Modified (STOR-M) tokamak for the first time to study these density fluctuations with wave-numbers in the range k = 5 /cm to 10 /cm. The fluctuations are found to follow k¦Ñs scaling consistent with ion drift waves; signatures of the electron temperature gradient (ETG) mode connected with anomalous electron losses are not detected. The fluctuation level in the STOR-M is measured to be ntilda/n ¡Ö 0.1 at a mean perpendicular wave-number of kperp ¡Ö 7 /cm and is reported for the first time. The fluctuation levels are inversely proportional to the energy confinement time suggesting that these fluctuations are driving anomalous particle and energy losses from the STOR-M. The system is now fully operational and this work paves the way for future experiments with this equipment

Reconstructing ice dynamics in the central sector of the last British-Irish Ice Sheet

The central sector (NW England and Scottish borders) of the last British-Irish Ice Sheet exhibits a palimpsest glacial geological and geomorphological signature characteristic of multi-phase ice flow and ice-marginal fluctuations. Despite its influential position at the heart of the British-Irish Ice Sheet, sourced from major ice dispersal centres of the northern Pennines, Lake District and Southern Uplands, and drained via fast-flowing outlets such as the Irish Sea Ice Stream, the region remains poorly constrained, both temporally and in terms of ice-flow dynamics. The principle goal of this thesis was therefore to reconstruct the palaeoglaciology of the central sector of the British-Irish Ice Sheet during the last glacial cycle, focusing on: (1) ice-flow dynamics with respect to palaeo-ice divides, ice-dispersal centres, flow trajectories and flow phasing; (2) the relative chronology of ice flows during advance and decay of the ice sheet; and (3) evidence for ice stream activity either within or sourced from the study area. The thesis adopted a dual approach involving both geomorphological mapping and sedimentological analysis. A 5 m resolution NEXTMap DEM was used to map over 9,000 individual landforms including subglacial lineations, hummocky terrain, moraines, meltwater channels, eskers and glaciofluvial sediment accumulations. Subglacial lineations were subdivided into discrete flow sets demarcating distinctive flow phases, and a relative chronology produced from cross-cutting relationships. Thirteen field sites, concentrated in the Solway Lowlands, supported by data collected from over 200 boreholes enabled detailed stratigraphic and sedimentological analysis to be carried out. This included stratigraphic logging, the collection of macrofabrics, particle size and geochemistry analysis on till matrixes, clast lithological counts, varve analysis and microstructural (thin sections) data. Results from this study have demonstrated that the central sector of the ice sheet was characterised by repeated ice-flow switches, initiation and termination of ice streams, drawdown into ice streams, repeated ice-marginal fluctuations (the Scottish and Blackhall Wood Re-advances) and the production of large volumes of meltwater, often impounded to form ice-dammed lakes. Six main stages of ice flow have been recognised in the region, of which stage I is thought to indicate the period of maximum ice expansion, while stages II-VI record the deglacial history. A pre-stage I event is also discussed and can be reconciled with the initial expansion of ice out of upland dispersal centres. Stage I was characterised by ice flowing eastwards across the country through major topographic lows of the Stainmore and Tyne gaps. The Tyne Gap was occupied by a topographic ice stream, which was heavily influenced by the changing dominances of both Lake District and Southern Upland ice-dispersal centres. Migration of ice divides back towards upland dispersal centres during stage II resulted in the flow of ice through the Stainmore Gap being cut-off, while the northern edge of the Tyne Gap ice stream was breached by a SE ice flow down the N Tyne Valley. Despite the maintenance of the Irish Sea Ice Stream off the western coast of Cumbria throughout stage III, the Tyne Gap and Solway Lowlands underwent widespread deglaciation. Meltwater from the Tyne Gap was routed into Glacial-Lake Wear via a major proglacial drainage network in the South Tyne Valley, while the natural basin of the Solway Lowlands also ponded-up (Glacial-Lake Blackhall Wood) as drainage became impeded by the Irish Sea Ice Stream. The overall pattern of retreat was reversed during the Blackhall Wood Re-advance (stage IV), during which ice was vigorously drawn down into the Irish Sea Ice Stream. Stage V was characterised by the continued retreat of ice out of the central sector of the British-Irish Ice Sheet; with the vast amounts of meltwater generated impounded in ice-marginal lake systems (Glacial-Lake Carlisle), or routed through meltwater channel networks or evolving glacier karst (Brampton kame belt). The landforms of the Brampton kame belt can be reconciled with ice stagnation on the reverse slope of the Tyne Gap, and is thought to have formed one component of a much larger, time-transgressive drainage network involving the Pennine escarpment and Tyne Gap meltwater channel systems. The final recognised stage in the glacial history of the region was the Scottish Re-advance, a brief incursion of ice, sourced from the Southern Uplands, onto the fringe of the Solway Lowlands. A large glacial lake is identified to have formed at the ice front, dammed against ice in the Irish Sea basin and delimited by a large deltaic complex at Holme St. Cuthbert

Testing and validation of a modified bride-type nonsuperconducting fault current limiter

As the amount of distributed generation (DG) integrated into the distribution network keeps increasing, this leads to an increase in the levels of fault current in the network, and this will result in the network having a fault current above what the existing protecting devices can handle. Hence, an upgrade of protective devices will be necessitated. A lot of techniques have been developed to mitigate against high fault currents. Some of these techniques with their limitations include current-limiting fuses that need constant replacement after an operation; circuit breakers that are very expensive for high current applications; isolation transformers that result in additional network power losses; and current-limiting and air-core reactors that impede the voltage stability of the network. Following these shortcomings, fault current limiters saw the light as the paramount solution to restrain fault currents in the distribution network. This research work is a follow-up of previous research that was on the design of a modified bridge-type nonsuperconducting fault current limiter (MBNSFCL) for application in the distribution network. In this paper, the designed MBNSFCL is tested and validated on two standard IEEE distribution networks, which are the IEEE 13 and the 33 node test networks. The simulation was done using PSCAD/EMTDC. In the case of the IEEE 13 node, the occurrence of a 3 phase to ground fault on the swing bus leads to the source current shooting from an amplitude of 0.602 kA on phase A, 0.335 kA on phase B, and 0.356 kA on phase C to 34.996 kA on phase A, 35.126 kA on phase B, and 34.983 kA on phase C. The fitting of the MBNSFCL into the test network restrains the fault current below the nominal line current, a level at which the circuit breaker can comfortably clear. The virtue of the MBNSFCL is also established when tested on the IEEE 33 node test network. This reveals the reliability of the proposed MBNSFCL for application in the distribution network

Posterior inferotemporal cortex cells use multiple input pathways for shape encoding

In the macaque monkey brain, posterior inferior temporal (PIT) cortex cells contribute to visual object recognition. They receive concurrent inputs from visual areas V4, V3, and V2. We asked how these different anatomical pathways shape PIT response properties by deactivating them while monitoring PIT activity in two male macaques. We found that cooling of V4 or V2|3 did not lead to consistent changes in population excitatory drive; however, population pattern analyses showed that V4-based pathways were more important than V2|3-based pathways.Wedid not find any image features that predicted decoding accuracy differences between both interventions. Using the HMAX hierarchical model of visual recognition, we found that different groups of simulated “PIT” units with different input histories (lacking “V2|3 or “V4 input) allowed for comparable levels of object-decoding performance and that removing a large fraction of “PIT” activity resulted in similar drops in performance as in the cooling experiments. We conclude that distinct input pathways to PIT relay similar types of shape information, with V1-dependent V4 cells providing more quantitatively useful information for overall encoding than cells in V2 projecting directly to PIT

Measuring the difference between actual and reported food intakes in the context of energy balance under laboratory conditions

Acknowledgements The present study was funded by the Food Standards Agency, UK. The Food Standards Agency had no role in the design, analysis or writing of this article. The authors’ responsibilities were as follows: R. J. S., L. M. O’R. and G. W. H. designed the research; L. M. O’R. and Z. F. conducted the research and analysed the data; G. W. H. performed the statistical analyses; P. R. carried out the DLW analysis; R. J. S. had primary responsibility for the final content; R. J. S., L. M. O’R., Z. F., S. W. and M. B. E. L. wrote the paper.Peer reviewedPublisher PD

Glacial geomorphology of the northern Kivalliq region, Nunavut, Canada, with an emphasis on meltwater drainage systems

This paper presents a glacial geomorphological map of glacial lineations, ribbed terrain, moraines, meltwater channels (subglacial and ice-marginal/proglacial), eskers, glaciofluvial deposits, ice-contact outwash fans and deltas and abandoned shorelines on the bed of the former Laurentide Ice Sheet in northern Canada. Mapping was compiled from satellite imagery and digital elevation data and landforms were digitised directly into a Geographical Information System. The map reveals a complex glacial history characterised by multiple ice-flow events, including fast-flowing ice-streams. Moraines record a series of pauses or re-advances during overall SE retreat towards the Keewatin Ice Divide. The distribution of subglacial meltwater landforms indicates that several distinctive scales and modes of drainage system operated beneath the retreating ice sheet. This includes a large (>100 km) integrated network of meltwater channels, eskers, ice-contact outwash fans and deltas and glaciofluvial deposits that originates at the northern edge of Aberdeen Lake. The map comprises zone 66 of the Canadian National Topographic System, which encompasses an area of 160,000 km2. It is presented at a scale of 1:500,000 and is designed to be printed at A0 size

Statutory frameworks, institutions and policy processes for climate adaptation : Final Report

Funded under the National Climate Change Adaptation Research Facility, this study addresses two objectives: To assess the extent to which existing statutory frameworks, associated institutions and policy processes support or impede national adaptation planning and practice, and To make a significant contribution to the development and implementation of a strategic national policy framework. The rationale for conducting this study was two-fold. First, that significant climate change is unavoidable and that it is in Australia’s national interest to adapt to those changes. Climate impacts are many and varied, direct and indirect, hard to predict and quantify generally but particularly at the local scale, and impacts will inevitably affect all sectors and jurisdictions. For this reason, it is a complex policy problem. The IPCC, for example, identifies ten key areas of impact for Australia including increasing frequency and intensity of extreme events such as droughts, bushfires and floods, higher peak temperatures for longer periods of time, and sea level rise. Despite the lack of hard economic data with respect to costs and benefits that might underpin formal business cases to determine precise levels of investment needed for adaptation, the case to adapt is compelling considering the projected effects to Australia’s economy, infrastructure, communities, environment and human life. Second, Australia’s capacity to adapt to climate change will rely on robust, efficient, transparent, fair and flexible institutions which build a resilient and enabling environment in which the necessary behavioural change can occur. While humans and our institutions have a remarkable capacity to adapt to all manner of change, this can occur at great cost to society as a whole or certain segments of it without the guiding hand of judicious policy intervention. This report synthesises our key findings against the two project objectives. In doing so, it focuses on (i) where institutional arrangements currently support or impede climate adaptation policy, and (ii) where revisions or new institutions may be required, and the potential for a strategic national policy framework to achieve those reforms

Reconstructing dynamics of the Baltic Ice Stream Complex during deglaciation of the Last Scandinavian Ice Sheet

Landforms left behind by the last Scandinavian Ice Sheet (SIS) offer an opportunity to investigate controls governing ice sheet dynamics. Terrestrial sectors of the ice sheet have received considerable attention from landform and stratigraphic investigations. In contrast, despite its geographical importance, the Baltic Sea remains poorly constrained due to limitations in bathymetric data. Both ice-sheet-scale investigations and regional studies at the southern periphery of the SIS have considered the Baltic depression to be a preferential route for ice flux towards the southern ice margin throughout the last glaciation. During the deglaciation the Baltic depression hosted the extensive Baltic Ice Lake, which likely exerted a considerable control on ice dynamics. Here we investigate the Baltic depression using newly available bathymetric data and peripheral topographic data. These data reveal an extensive landform suite stretching from Denmark in the west to Estonia in the east and from the southern European coast to the Åland Sea, comprising an area of 0.3 million km2. We use these landforms to reconstruct aspects of the ice dynamic history of the Baltic sector of the ice sheet. Landform evidence indicates a complex retreat pattern that changes from lobate ice margins with splaying lineations to parallel mega-scale glacial lineations (MSGLs) in the deeper depressions of the Baltic Basin. Ice margin still-stands on underlying geological structures indicate the likely importance of pinning points during deglaciation, resulting in a stepped retreat signal. Over the span of the study area we identify broad changes in the ice flow direction, ranging from SE–NW to N–S and then to NW–SE. MSGLs reveal distinct corridors of fast ice flow (ice streams) with widths of 30 km and up to 95 km in places, rather than the often-interpreted Baltic-wide (300 km) accelerated ice flow zone. These smaller ice streams are interpreted as having operated close behind the ice margin during late stages of deglaciation. Where previous ice-sheet-scale investigations inferred a single ice source, our mapping identifies flow and ice margin geometries from both Swedish and northern Bothnian sources. We anticipate that our landform mapping and interpretations may be used as a framework for more detailed empirical studies by identifying targets to acquire high-resolution bathymetry and sediment cores and also for comparison with numerical ice sheet modelling.</p

A revision of the British Chronostratigraphy within the Last Glacial-Interglacial Cycle based on new evidence from Arclid, Cheshire UK

Of the 24 Greenland interstadials (GI) in the Last Glacial-interglacial cycle (LGIC) only five are conventionally recognised in Britain. This paper aims to improve understanding of the LGIC in Britain from a site at Arclid, Cheshire. Sediments were characterised and luminescence used to establish a chronology. This found that the Chelford Sand Formation spans 77-47 ka with sand deposited initially by aeolian but later by fluvial transportation. Coleoptera and Diptera from the basal peat lens provided a reconstruction for a heather-rich heathland environment grazed by large herbivores, with summer temperatures between 13-18° C, and winter temperatures between -14 and 1°C. Flies included the earliest records of the blood-sucking horsefly Haematopota pluvialis, and the soldierfly Chloromyia formosa. The overlying Stockport Sand Formation was deposited fluvioglacially between 47-41 ka with the upper Stockport Till formed by the advance of the last British icesheet after ~33 ka. Stenothermic beetle analysis from Arclid indicate similarities with results from other British mid LGIC sites, some of which are at or beyond the limit of radiocarbon dating and may be of a similar age to Arclid. Basal organic sediments found at Arclid along with other reassigned sites are proposed as a new Arclid Interstadial. A revised British LGIC chronostratigraphy has the Wretton, Chelford and Brimpton Interstadials and the previously suggested but not widely recognised Cassington Interstadial. The Arclid Interstadial occurred after these, but prior to the Upton Warren Interstadial complex. This closes the previous gap in interstadials between the Brimpton Interstadial and the Upton Warren Interstadial complex within the British chronostratigraphy

An ice-sheet scale comparison of eskers with modelled subglacial drainage routes

Eskers record a time-integrated signature of channelised meltwater drainage during deglaciation providing vital information on the nature and evolution of subglacial drainage. In this paper, we compare the spatial pattern of eskers beneath the former Laurentide Ice Sheet with subglacial drainage routes diagnosed at discrete time intervals from the results of a numerical icesheet model. Perhaps surprisingly, we show that eskers predominantly occur in regions where modelled subglacial water flow is low. Eskers and modelled subglacial drainage routes were found to typically match for lengths <10 km, and most eskers show a better agreement with the routes close to the ice margin just prior to deglaciation. This supports a time-transgressive esker pattern, with formation in short (<10 km) segments of conduit close behind a retreating ice margin, and probably associated with thin, stagnant or sluggish ice. Esker forming conduits were probably dominated by supraglacially fed meltwater inputs. We also show that modelled subglacial drainage routes containing the largest concentrations of meltwater show a close correlation with palaeo-ice stream locations. The paucity of eskers along the terrestrial portion of these palaeo-ice streams and meltwater routes is probably due to the prevalence of distributed drainage and the high erosion potential of fast-flowing ice