1,650 research outputs found

    The co-construction of energy provision and everyday practice: integrating heat pumps in social housing in England

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    Challenges of energy security, low carbon transitions, and electricity network constraints have led to a shift to new, efficient technologies for household energy services. Studies of such technological innovations usually focus on consumer information and changes in behaviour to realise their full potential. We suggest that regarding such technologies in existing energy provision systems opens up questions concerning how and why such interventions are delivered. We argue that we must understand the ways by which energy systems are co-constituted through the habits and expectations of households, their technologies and appliances, alongside arrangements associated with large-scale socio-technical infrastructures. Drawing on research with air-source-to-water heat pumps (ASWHP), installed as part of a large trans-disciplinary, utility-led research and demonstration project in the north of England, we investigate how energy services provision and everyday practice shapes new technologies uptake, and how such technologies mediate and reconfigure relations between users, providers and infrastructure networks. While the installation of ASWHP has led to role differentiation through which energy services are provided, the space for new forms of co-provision to emerge is limited by existing commitments to delivering energy services. Simultaneously, new forms of interdependency emerge between users, providers and intermediaries through sites of installation, instruction, repair and feedback. We find that although new technologies do lead to the rearrangement of practices, this is often disrupted by obduracy in the conventions and habits around domestic heating and hot water practices that have been established in relation to existing systems of provision. Rather being simply a matter of increasing levels of knowledge in order to ensure that such technologies are adopted effi ciently and effectively, our paper demonstrates how systemic arrangements of energy provision and everyday practice are co-implicated in socio-technical innovation by changing the nature of energy supply and use

    Soil Nitrification Inhibition with Plantain (\u3ci\u3ePlantago lanceolata\u3c/i\u3e)

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    One strategy to reduce nitrogen losses from intensively grazed forage systems is to slow the first stage of soil nitrification, specifically inhibiting the microbial oxidation of ammonium to nitrite. Plantain (Plantago lanceolata) leaves and roots are known to contain several bioactive compounds (e.g., aucubin, catalpol and verbascoside) that may contribute to this inhibition. Recent laboratory studies indicate that this inhibition occurs via consumption by grazing animals of precursor bioactive compounds in aboveground biomass and their subsequent excretion as secondary metabolites in urine and/or via active exudation from the roots. Different cultivars of plantain have been shown to impart differing nitrification inhibition activity via both mechanisms. The urinary effect was assessed by determination of net soil nitrification in soil microcosms treated with urine from sheep fed a diet containing either perennial ryegrass or plantain. Analyses showed significant treatment effects on the rate of net nitrification and microbial community structure over time. A preliminary evaluation of the root exudate effect involved the collection of root exudates from six plantain cultivars grown in a hydroponic system. The assay of the root exudates against a pure culture of an ammonium-oxidising bacterium indicated differences in the amount of inhibition imparted by the exudates of each cultivar. The exact means of soil nitrification inhibition by either mechanism is as yet unconfirmed. However, it is likely that these compounds (or derivatives thereof) inhibit the first enzymatic step of nitrification directly, without harm to the soil microbiome as a whole

    Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes

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    The importance of lotic systems as sinks for nitrogen inputs is well recognized. A fraction of nitrogen in streamflow is removed to the atmosphere via denitrification with the remainder exported in streamflow as nitrogen loads. At the watershed scale, there is a keen interest in understanding the factors that control the fate of nitrogen throughout the stream channel network, with particular attention to the processes that deliver large nitrogen loads to sensitive coastal ecosystems. We use a dynamic stream transport model to assess biogeochemical (nitrate loadings, concentration, temperature) and hydrological (discharge, depth, velocity) effects on reach-scale denitrification and nitrate removal in the river networks of two watersheds having widely differing levels of nitrate enrichment but nearly identical discharges. Stream denitrification is estimated by regression as a nonlinear function of nitrate concentration, streamflow, and temperature, using more than 300 published measurements from a variety of US streams. These relations are used in the stream transport model to characterize nitrate dynamics related to denitrification at a monthly time scale in the stream reaches of the two watersheds. Results indicate that the nitrate removal efficiency of streams, as measured by the percentage of the stream nitrate flux removed via denitrification per unit length of channel, is appreciably reduced during months with high discharge and nitrate flux and increases during months of low-discharge and flux. Biogeochemical factors, including land use, nitrate inputs, and stream concentrations, are a major control on reach-scale denitrification, evidenced by the disproportionately lower nitrate removal efficiency in streams of the highly nitrate-enriched watershed as compared with that in similarly sized streams in the less nitrate-enriched watershed. Sensitivity analyses reveal that these important biogeochemical factors and physical hydrological factors contribute nearly equally to seasonal and stream-size related variations in the percentage of the stream nitrate flux removed in each watershed

    Fostering active network management through SMEs’practises

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    Managing the electricity network through ‘smart grid’ systems is a key strategy to address challenges of energy security, low carbon transitions and the replacement of ageing infrastructure networks in the UK. Small and medium enterprises (SMEs) have a significant role in shaping patterns of energy consumption. Understanding how their activities interrelate with changes in electricity systems is critical for active network management. A significant challenge for the transformation of electricity systems involves comprehending the complexity that stems from the variety of commercial activities and diversity of social and organizational practises among SMEs that interact with material infrastructures. We engage with SMEs to consider how smart grid interventions ‘fit’ into everyday operational activities. Drawing on analysis of empirical data on electricity use, smart metre data, surveys, interviews and ‘energy tours’ with SMEs to understand lighting, space heating and cooling, refrigeration and IT use, this paper argues for experimenting with the use of practise theory as a framework for bringing together technical and social aspects of energy use in SMEs. This approach reveals that material circumstances and temporal factors shape current energy demand among SMEs, with ‘connectedness’ an emergent factor

    Continuous-infusion verapamil with etoposide in relapsed or resistant paediatric cancers.

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    This study evaluates the use of a multidrug resistance (MDR) modulator (verapamil) in combination with a standard dose of single-agent etoposide in relapsed or refractory paediatric malignancy. A total of 20 patients (median age 6.5 years) were treated with an infusion of verapamil (loading dose 0.1 mg kg-1, followed by continuous infusion 0.15 mg kg-1 h-1) for 72 h. Etoposide was given daily (150 mg m-2 day-1) for three doses (each over 1 h); the first dose was given 12 h into the verapamil infusion. Cardiovascular toxicity was monitored by ECG and 2 hourly blood pressure and pulse recordings. Verapamil and norverapamil plasma concentrations were measured daily. Disease response was assessed after two courses. A total of 29/35 treatment courses were given at the desired verapamil dose; five courses required a dose reduction owing to cardiovascular toxicity. No patient required intensive monitoring. All patients who developed cardiovascular toxicity were over 14 years old. There was no correlation between plasma verapamil or norverapamil concentrations and toxicity. There were six partial responses (three rhabdomyosarcoma, three neuroblastoma) after two courses, but because of variation in the dose and schedule of etoposide these cannot be unequivocally contributed to MDR reversal. In conclusion, a regimen using a continuous infusion of verapamil combined with divided-dose etoposide is tolerable in children, and this strategy may be effective in refractory neuroblastoma and rhabdomyosarcoma

    Investigations in vivo of the effects of carbogen breathing on 5-fluorouracil pharmacokinetics and physiology of solid rodent tumours

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    Purpose: We have shown previously that carbogen (95% 02, 5% CO2) breathing by rodents can increase uptake of anticancer drugs into tumours. The aim of this study was to extend these observations to other rodent models using the anticancer drug 5-fluorouracil (5FU). 5FU pharmacokinetics in tumour and plasma and physiological effects on the tumour by carbogen were investigated to determine the locus of carbogen action on augmenting tumour uptake of 5FU. Methods: Two different tumour models were used, rat GH3 prolactinomas xenografted s.c. into nude mice and rat H9618a hepatomas grown s.c. in syngeneic Buffalo rats. Uptake and metabolism of 5FU in both tumour models with or without host carbogen breathing was studied non-invasively using fluorine-19 magnetic resonance spectroscopy (19F-MRS), while plasma samples from Buffalo rats were used to construct a NONMEM pharmacokinetic model. Physiological effects of carbogen on tumours were studied using 31P-MRS for energy status (NTP/Pi) and pH, and gradient-recalled echo magnetic resonance imaging (GRE-MRI) for blood flow and oxygenation. Results: In both tumour models, carbogan-induced GRE-MRI signal intensity increases of ∼60% consistent with an increase in tumour blood oxygenation and/or flow. In GH3 xenografts, 19F-MRS showed that carbogen had no significant effect on 5FU uptake and metabolism by the tumours, and 31P-MRS showed there was no change in the NTP/Pi ratio. In H9618a hepatomas, 19F-MRS showed that carbogen had no effect on tumour 5FU uptake but significantly (p=0.0003) increased 5FU elimination from the tumour (i.e. decreased the t1/2) and significantly (p=0.029) increased (53%) the rate of metabolism to cytotoxic fluoronucleotides (FNuct). The pharmacokinetic analysis showed that carbogen increased the rate of tumour uptake of 5FU from the plasma but also increased the rate of removal. 31P-MRS showed there were significant (p≤0.02) increases in the hepatoma NTP/Pi ratio of 49% and transmembrane pH gradient of 0.11 units. Conclusions: We suggest that carbogen can transiently increase tumour blood flow, but this effect alone may not increase uptake of anticancer drugs without a secondary mechanism operating. In the case of the hepatoma, the increase in tumour energy status and pH gradient may be sufficient to augment 5FU metabolism to cytotoxic FNuct, while in the GH3 xenografts this was not the case. Thus carbogen breathing does not universally lead to increased uptake of anticancer drug
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