The significance of organic carbon and nutrient export from peatland-dominated landscapes subject to disturbance, a stoichiometric perspective

The terrestrial-aquatic interface is a crucial environment in which to consider the fate of exported terrestrial carbon in the aquatic system. Here the fate of dissolved organic carbon (DOC) may be controlled by nutrient availability. However, peat-dominated headwater catchments are normally of low nutrient status and thus there is little data on how DOC and nutrient export co-varies. We present nutrient and DOC data for two UK catchments dominated by peat headwaters. One, Whitelee, is undergoing development for Europe's largest windfarm. Glen Dye by comparison is relatively undisturbed. At both sites there are significant linear relationships between DOC and soluble reactive phosphorus and nitrate concentrations in the drainage waters. However, inter-catchment differences exist. Changes in the pattern of nutrient and carbon export at Whitelee reveal that landscape disturbance associated with windfarm development impacts the receiving waters, and that nutrient export does not increase in a stoichiometric manner that will promote increase in microbial biomass but rather supports aquatic respiration. In turn greater CO2 efflux may prevail. Hence disturbance of terrestrial carbon stores may impact the both the aquatic and gaseous carbon cycle. We suggest estimates of aquatic carbon export should inform the decision-making process prior to development in ecosystems and catchments with high terrestrial carbon storage

GHz bandwidth electro-optics of a single self-assembled quantum dot in a charge-tunable device

The response of a single InGaAs quantum dot, embedded in a miniaturized charge-tunable device, to an applied GHz bandwidth electrical pulse is investigated via its optical response. Quantum dot response times of 1.0 \pm 0.1 ns are characterized via several different measurement techniques, demonstrating GHz bandwidth electrical control. Furthermore a novel optical detection technique based on resonant electron-hole pair generation in the hybridization region is used to map fully the voltage pulse experienced by the quantum dot, showing in this case a simple exponential rise.Comment: 7 pages, 4 figure

Enhancing urban autonomy : towards a new political project for cities.

As the 21st Century world assumes an increasingly urban landscape, the question of how definitive urban spaces are to be governed intensifies. At the heart of this debate lies a question about the degree and type of autonomy that towns and cities might have in shaping their economic, environmental, social and cultural geography. This paper aims to examine this question. Starting with the premise that the degree of autonomy any particular town or city has is inherently an empirical question – one which can only be conceptualised in relational terms vis-à-vis the distributed, networked and territorialised responsibilities and powers of the city and the nation-state and other zones of connection – we examine four different contexts where debates over autonomy have intensified in recent history (Brazil, UK, India and South Africa). Drawing on recent respective histories, we identify key elements and enablers in the making of urban autonomy: a characteristic that exists in a variety of guises and forms and creates a patchwork landscape of differentially powerful fragments. We reveal how, beyond its characteristic as a political ideal, autonomy surfaces as a practice that emerges from within specific sectors of particular societies and through their relationship with national and regional politics. Four alternative forms of urban autonomy are delineated: fragmented, coerced (or enclave), distributed and networked. We contend that the spatial templates for autonomy are not predetermined but can be enhanced in multiple different sites and forms of political space within the city. This enhancement appears essential for the integration and strengthening of capacities for sustainable and just forms of development throughout the urban

Enhancing urban autonomy: towards a new political project for cities

As the 21st Century world assumes an increasingly urban landscape, the question of how definitive urban spaces are to be governed intensifies. At the heart of this debate lies a question about the degree and type of autonomy that towns and cities might have in shaping their economic, environmental, social and cultural geography. This paper aims to examine this question. Starting with the premise that the degree of autonomy any particular town or city has is inherently an empirical question – one which can only be conceptualised in relational terms vis-à-vis the distributed, networked and territorialised responsibilities and powers of the city and the nation-state and other zones of connection – we examine four different contexts where debates over autonomy have intensified in recent history (Brazil, UK, India and South Africa). Drawing on recent respective histories, we identify key elements and enablers in the making of urban autonomy: a characteristic that exists in a variety of guises and forms and creates a patchwork landscape of differentially powerful fragments. We reveal how, beyond its characteristic as a political ideal, autonomy surfaces as a practice that emerges from within specific sectors of particular societies and through their relationship with national and regional politics. Four alternative forms of urban autonomy are delineated: fragmented, coerced (or enclave), distributed and networked. We contend that the spatial templates for autonomy are not predetermined but can be enhanced in multiple different sites and forms of political space within the city. This enhancement appears essential for the integration and strengthening of capacities for sustainable and just forms of development throughout the urban

Chylous ascites associated with chylothorax; a rare sequela of penetrating abdominal trauma: a case report

We present the case of a patient with the rare combination of chylous ascites and chylothorax resulting from penetrating abdominal injury. This patient was successfully managed with total parenteral nutrition. This case report is used to highlight the clinical features and management options of this uncommon but challenging clinical problem

The significance of organic carbon and nutrient export from peatland-dominated landscapes subject to disturbance

International audienceThe terrestrial-aquatic interface is a crucial environment in which to consider the fate of exported terrestrial carbon in the aquatic system. To a large extent the fate of dissolved organic carbon (DOC) may be controlled by nutrient availability. However, peat-dominated headwater catchments are normally considered of low nutrient status and thus there is little data on the interaction of DOC and nutrients. Here we present nutrient and DOC data exported from two UK catchments, both dominated by peat headwaters, but of differing land-use. Glen Dye is a moorland with no trees; Whitelee has partially forested peats and peaty podzols, and is now undergoing development to host Europe's largest on-shore windfarm, the Whitelee Windfarm. There are significant linear relationships between DOC and soluble reactive phosphorus and nitrate concentrations in the drainage waters, but inter-catchment differences exist. Changes in the pattern of nutrient and carbon export in Whitelee suggest that disturbance of peatlands soils can impact the receiving water and that nutrient export does not increase in a stoichiometric manner that will promote increase in biomass. As such the changes are more likely to cause increased aquatic respiration, and thus lead to higher dissolved CO2 concentrations (and therefore CO2 efflux). Hence disturbance of terrestrial carbon stores may also impact the gaseous carbon cycle. Confirming the source of carbon and nutrients in these study sites is not possible. However, nearby 14C measurements are in keeping with other published literature values from similar sites which show C in DOM exported from peatlands is predominantly modern, and thus supports an interpretation that nutrients, additional to carbon, are derived from shallow soils. Estimates of organic carbon loss from Whitelee catchments to the drainage waters suggest a system where losses are approaching likely sequestration rates. We suggest such sequestration assessment should inform the decision-making tools required prior to development of terrestrial carbon stores

The practical feasibility of using RFID in a metal environment

Passive Radio Frequency Identification (RFID) has revolutionized the way in which products are identified. This paper considers the effect of metals on the performance of RFID at ultra high frequency (UHF). The paper establishes read patterns in space, highlighting the interference of RF waves due to three different metals, one ferrous and the other two non ferrous, when placed behind a transponder. The effect of thickness of the metal plate is also examined. Different metals have been found to have different interference effects although there are some similarities in their read patterns related to their material properties. Also experiments have been carried out to identify and establish various methods of improving this performance. Finally, differences between performance-measuring parameters, namely attenuating transmitted power and calculating read rate at a fixed attenuation are established and possible reasons of these observations are presented