196 research outputs found
Short-range correlations in two-nucleon knockout reactions
A theory of short-range correlations in two-nucleon removal due to elastic
breakup (diffraction dissociation) on a light target is developed. Fingerprints
of these correlations will appear in momentum distributions of back-to-back
emission of the nucleon pair. Expressions for the momentum distributions are
derived and calculations for reactions involving stable and unstable nuclear
species are performed. The signature of short-range correlations in other
reaction processes is also studied.Comment: Nuclear Physics A, in pres
Geothermal Energy Challenge Fund: the Guardbridge Geothermal Technology Project
GEOTHERMAL ENERGY CHALLENGE EXECUTIVE SUMMARY
This feasibility study investigates whether a geothermal district heating system,
which accesses Hot Sedimentary Aquifer (HSA) resources underlying a brownfield
site at Guardbridge in northeast Fife, can be developed in a cost-effective manner.
This project’s scope is to assess the available geological information and estimate
the hot saline aquifer heat supply, calculate the current heat demand at the
Guardbridge site, Guardbridge village, and the nearby towns of Leuchars and
Balmullo, and to incorporate future Guardbridge development plans (provided by
the University of St Andrews) and anticipated growth in housing stock (from Fife
Council) to estimate future heat demand. The capital, maintenance and repair
costs for the geothermal well and designed district heating network are used to
develop economic models for a number of district heat network scenarios. A key
aspect of this study is an evaluation of the opportunities to cost effectively de-risk
deep geothermal exploration in Central Scotland, and to outline the potential for
developing geological heat storage systems. The study identifies the key
legislative and environmental issues, risks and uncertainties associated with any
exploration and production, involves stakeholder engagement, and makes
recommendations for a Phase 2 stage for geothermal heat development at
Guardbridge.
Two of the key outputs from this feasibility study will be an economic model
and business case based on different heat demand options, and an optimised
model of well design based on different exploration strategies. Both are
transferable to similar operations at other geothermal sites. The key objectives
are therefore to:
(a)design a geothermal well that will be drilled in Phase 2 of the project, and
secure valuable information on Fife regional sub-surface geology and
geothermal properties of the primary aquifer,
(b)explore how advanced drilling techniques, such as directional drilling, can
be deployed to improve geothermal recovery,
(c) demonstrate how a geothermal system can integrate with an existing
biomass heating installation to optimise both schemes and provide a district
heat network for on-site industries and the local community,
(d)evaluate the potential for storage of seasonal heat energy in the subsurface
(a first in Scotland), and
(e)assess the relative merits of water treatment and on-site recycling, reinjection
or disposal to sea.
A regional geological model was constructed using available
data from the British Geological Survey, published data and academic theses. The
sub-surface geology was interpreted from surface geology and extrapolating the
local behaviour of geological structures into the Guardbridge area. Modelling the
geology involved defining the orientation and width of a natural fault zone, which
could be a significant influence on the behaviour of the Hot Sedimentary Aquifers.
The rock units of interest in this study are the Upper Devonian Scone Sandstone,
Glenvale Sandstone, Knox Pulpit and Kinnesswood formations, and the latter two
units are previously identified as having the highest potential to be highly
productive aquifers. The presence of a major fault near the Guardbridge site
means that the target aquifers are at very different depths on either side of the
fault. The report therefore investigates and evaluates three well options to target
the different aquifers at the varying depths on either side of the fault.
Hydrogeological modelling was conducted using FEFLOW® to evaluate the
behaviour of the fault on fluid flow rates, and to predict the necessary
conductivities to produce reasonable, economic and sustainable rates of fluid
extraction. Although not an accurate model of the Guardbridge site, and limited
by a significant lack of data constraining the important parameters, the flow
simulations suggest that fracture permeability in the aquifers and underlying rocks
is needed to sustain the flows recommended by this study, and re-injection would
be required if a producing well was to be sustainable over many decades.
Regionally developed rock quality predictors have been used to estimate the
permeability and temperature of the target aquifer intervals in the three selected
well options at, or near, Guardbridge. Oil field well simulation tools have been
used to estimate water flow rates, temperature profiles, and circulating rates from
different geological models of the wells. Two of the wells, GB-1 and ES-1, are not
expected to penetrate enough high permeability sandstone to support the
minimum water flow rates of 5 l/s and so are ruled out as viable aquifer producers.
GB-2 is a deviated well that penetrates the Kinnesswood and Knox Pulpit
formations, the best quality regional aquifers, in a zone where the fault may
enhance the permeability even more, and has potential to supply 5 to 20 l/s of
water at a surface temperature of 25 oC (± 2 oC). Such a well will be produced
using an electric submersible pump which will require 20 - 40 kw of power to
deliver 15 l/s of flow (although the volumetric rate will vary with the rock quality).
GB-2 is taken forward and drilling designs are provided with three outcomes: 1)
a dry hole scenario; 2) a 5 l/s scenario; and, 3) a 15 l/s scenario.
The vertical wells have been modelled as heat pump circulating wells, and
therefore would not produce any aquifer water at the surface. Only deeper wells,
up to 2500 m, have the potential to give surface temperature increase of 5 oC at
reasonable circulation rates (e.g. 8 l/s). A deep GB-1 well as a heat pump could
be taken forward in Phase 2 as an alternative heat source.
The proposed GB-2 deviated well can be drilled across the fault from the
Guardbridge site to a depth of 1200 m. A casing string set will isolate the shallow
geology and a slotted liner used to prevent hole collapse of the target intervals.
Such a well will require a 100 tonne conventional drilling rig and well control,
logging and coring tools will assess the aquifer quality. In the most likely case,
the drilling phase will take 24 days, including rig mobilisation and demobilisation.
If coring and logging demonstrate that the well will not flow adequately, then the
well will be suspended. Low cost options have been investigated that would allow
exploratory wells to be drilled and this could result in the recovery of regionally
significant data on the performance of the aquifers at depth, although none of the
boreholes could be completed to production stage due the drilling technology
employed.
The drilling scenarios investigated do not include a re-injection well, in order to
create an economically viable district heating network project, even though very
preliminary hydrogeological modelling demonstrates that re-injection is required
if the geothermal well is to be sustainable over 30+ years. Alternative
management of produced water investigated in this report are: water disposal-tosea
and partial-full water recycling and re-use on site. The first option could have
environmental consequences on the adjacent Eden Estuary, which is part of the
Tay River and Eden Estuary Special Protection Area, and these potential impacts
would need formal assessment by a competent authority (Fife Council and SNH)
as part of a Habitat Regulations Appraisal, and an Environmental Impact
Assessment is most likely required. The second option reduces the environmental
impacts on the estuary, but has additional CAPEX and OPEX costs which are
estimated. The opportunity to be innovative about partial water recycling and resale
should be investigated in Phase 2.
The heat demand is based on preliminary district heating network layouts at
different scales, based on the demand analysis. Demand has been assessed at
Guardbridge and the nearby towns of Leuchars and Balmullo, using the Scotland
Heat Map and future development data provided by the University of St Andrews
and the Fife Development Plan. These various options provide an indication of the
potential annual and peak heating demands that can then be compared against
the geothermal heating potential, and an economic modelling tool was developed
to analyse the performance of the overall system, including key performance
indicators to evaluate the financial viability. This analysis leads to a preliminary
network design and an economic model of the potential scheme.
The District Heating Opportunity Assessment Tool (DHOAT) designed for the
Danish Energy Agency analyses the Heat Map data and preliminary network
designs and provides peak and annual demands and key performance indicators,
namely total heat demand and indicative CAPEX, OPEX, REPEX and heat sales. All
input parameters are modelled with an uncertainty of ±10%. Based on this
analysis, the proposed development of one well and estimated heat supply is not
sufficient capacity to provide heat outside of the Guardbridge site itself. All district
heating network designs and economic models were therefore based on the
aggregated customer base of the Guardbridge site. The economic model assumes
that geothermal heat can supply 50% of the Guardbridge site needs (2,867
MWh/a), with a capacity of 0.42 MW, and the other 50% would be provided by
the biomass plant. Revenues from heat sales are based on a heat sale price scaling
(MWh and p/kWh) and costs of heat from the biomass plant.
An Excel model calculates the profitability of the scheme based on a CAPEX of
£530,000 for the heating network and £1,517,000 for the well completion, flow
tests and water treatment. OPEX and REPEX costs are principally power
consumption for the heat and distribution pumps (£280,000), and a ESP and heat
pump replacement after 10 years (£250,000). NPV and IRR are used to
demonstrate viability for potential investors over a 21-year period; the best case
scenario shows that the scheme might achieve a 10% IRR and a positive NPV.
However, the heat sale price is too low to create sufficient margin to make the
economic performance attractive. This is principally due to the cost of the
geothermal heat. The capital cost of the geothermal well is a significant portion of
the project CAPEX and does not vary with the well heat potential, which is a
relatively modest value given the temperature and flow rate estimates presented.
Flow rate is highly uncertain, while temperature is better constrained and low due
to the shallow depth of the proposed well. The district heating network requires
higher temperatures and the addition of a heat pump increases the capital costs
and adds a relatively high operating cost for the electricity to run the pump.
The carbon emissions reductions are compared to an individual gas boiler
alternative (business as usual [BAU]) and the geothermal-biomass heat network
shows an 84% reduction in carbon emissions, assuming that the biomass boilers
and geothermal heat pumps each supply 50% of the network demand. About 58%
of the emissions reduction (13,878 tonnes CO2/kWh relative to BAU) is attributed
to heat generation from the biomass plant and the remaining 42% (9,812 tonnes
CO2/kWh relative to BAU) is attributed to the geothermal well and the heat pump.
These figures are based on a model lifetime of 20 years. The value of this carbon
saving has not been included in the economic model, however it could be
considered to represent an additional savings compared to the business-as-usual
alternative.
The heating network can be enhanced at a subsequent stage to provide
combined heating and cooling for the site. This would increase the utilisation of
the heat pump by operating in combined heating and cooling mode during interseasonal
periods. Although not explored in any extensive technical or economic
sense, the system could also potentially be used to fill separate hot and cold
seasonal heat stores.
Requirements for Phase 2 would begin with a non-invasive geophysical survey
to provide imaging of the fault and the target aquifers in the subsurface. This
could be completed in three months. Phase 2 would most likely require the
preparation of an Environmental Statement before any drilling could commence
on site, particularly addressing the viability of disposal of water to the sea.
However, current developments at Guardbridge have required Environmental
Statements (i.e. since 2014) and much baseline data already exists. The time
required to complete an EIA range from 12 weeks to prepare the report, or up to
one year of time if SNH and Fife Council require additional new data. A benefit of
the Guardbridge site is therefore its status as an industrial site with a pre-existing
history in terms of Environmental Statements. Ideally, Phase 2 would culminate
in revised well designs, procurement of the drilling rig, and test drilling to intercept
the fault and target aquifers. The time and costs are estimated and depend on the
choice of drilling option. A positive outcome from a test borehole would lead to
the design of a full production well and progression of the project as a Technology
Demonstrator. Regardless of whether the test borehole proves that the
Guardbridge District Heating Network project is viable, the data recovered as part
of the test drilling (core samples, flow tests and water chemistry) will be highly
significant for de-risking hot sedimentary aquifer exploration across central
Scotland.
The economic feasibility of the Guardbridge geothermal heat project is
dependent on the best case scenario for flow rates, along with a large number of
other poorly constrained variables. It could be economic, but there is a very large
uncertainty in the geothermal heat estimates. However, the additional value in
the potential research that can be achieved at Guardbridge in de-risking hot
sedimentary aquifer exploration in the Central Belt of Scotland, as well as
integrating low carbon heat source exploration with other technologies, including
dual heating and cooling and water recycling, should be considered when deciding
to progress this project
A DNA-binding bromodomain-containing protein interacts with and reduces Rx1-mediated immune response to Potato Virus X
Plant NLR proteins enable the immune system to recognise and respond to pathogen attack. An early consequence of immune activation is transcriptional reprogramming. Some NLRs have been shown to act in the nucleus and interact with transcription factors. The Rx1 NLR protein of potato binds and distorts double-stranded DNA. However, the components of the chromatin localized Rx1-complex are largely unknown. Here we report a physical and functional interaction between Rx1 and NbDBCP, a bromodomain-containing chromatin-interacting protein. NbDBCP accumulates in the nucleolus, interacts with chromatin and redistributes Rx1 to the nucleolus in a subpopulation of imaged cells. Rx1 over-expression reduces NbDBCP interactions with chromatin. NbDBCP is a negative regulator of Rx1-mediated immune responses to potato virus X (PVX) and this activity requires an intact bromodomain. Previously, Rx1 has been shown to regulate the DNA-binding activity of a Golden2-like transcription factor, NbGlk1. Rx1 and NbDBCP act synergistically to reduce NbGlk1 DNA-binding suggesting a mode of action for NbDBCP’s inhibitory effect on immunity. This study provides new mechanistic insight into how a chromatin localised NLR complex co-ordinates immune signalling following pathogen perception
The experiences and needs of supporting individuals of young people who self-harm: A systematic review and thematic synthesis
Self-harm in young people is a serious international health concern that impacts on those providing informal support: the supporting individuals of young people. We aimed to highlight the experiences, views, and needs of these supporting individuals of young people. We conducted a systematic review and thematic synthesis: PROSPERO CRD42020168527. MEDLINE, PsycINFO, EMBASE, AMED, CINAHL, ASSIA, and Web of Science were searched from inception to 6 May 2020 with citation tracking of eligible studies done on 1 Oct 2021. Primary outcomes were experiences, perspectives, and needs of parents, carers, or other family members of young people aged 12-25. Searches found 6167 citations, of which 22 papers were included in synthesis. Supporting individuals seek an explanation for and were personally affected by self-harm in young people. It is important that these individuals are themselves supported, especially as they negotiate new identities when handling self-harm in young people, as they attempt to offer support. The GRADE-CERQual confidence in findings is moderate. Recommendations informed by the synthesis findings are made for the future development of interventions. Clinicians and health service providers who manage self-harm in young people should incorporate these identified unmet needs of supporting individuals in a holistic approach to self-harm care. Future research must co-produce and evaluate interventions for supporting individuals
Distinct Costimulatory Molecules Are Required for the Induction of Effector and Memory Cytotoxic T Lymphocytes
A successful T cell immune response has two major products: effector T cells which directly or indirectly remove the antigens, and memory T cells, which allow a faster and more efficient recall response when challenged by related antigens. An important issue is whether costimulatory molecules on the antigen-presenting cells are involved in determining whether T cells will differentiate into effector or memory cells after antigenic stimulation. To address this issue, we have produced mice with targeted mutations of either the heat-stable antigen (HSA), or both HSA and CD28. We show that CD28/B7 and HSA provide two alternative costimulatory pathways for induction of immunological memory to influenza virus. Furthermore, our results revealed that B7 is essential for the generation of effector T cells from either naive or memory T cells, while HSA is not necessary for the generation of effector T cells. Our results demonstrate that the induction of memory T cells and effector T cells can utilize distinct costimulatory molecules. These results have important implications on lineage relationship between effector and memory T cells
Recrystallization of amorphous nano-tracks and uniform layers generated by swift-ion-beam irradiation in lithium niobate.
The thermal annealing of amorphous tracks of nanometer-size diameter generated in lithium niobate (LiNbO3) by Bromine ions at 45 MeV, i.e., in the electronic stopping regime, has been investigated by RBS/C spectrometry in the temperature range from 250°C to 350°C. Relatively low fluences have been used (<1012 cm−2) to produce isolated tracks. However, the possible effect of track overlapping has been investigated by varying the fluence between 3×1011 cm−2 and 1012 cm−2. The annealing process follows a two-step kinetics. In a first stage (I) the track radius decreases linearly with the annealing time. It obeys an Arrhenius-type dependence on annealing temperature with activation energy around 1.5 eV. The second stage (II) operates after the track radius has decreased down to around 2.5 nm and shows a much lower radial velocity. The data for stage I appear consistent with a solid-phase epitaxial process that yields a constant recrystallization rate at the amorphous-crystalline boundary. HRTEM has been used to monitor the existence and the size of the annealed isolated tracks in the second stage. On the other hand, the thermal annealing of homogeneous (buried) amorphous layers has been investigated within the same temperature range, on samples irradiated with Fluorine at 20 MeV and fluences of ∼1014 cm−2. Optical techniques are very suitable for this case and have been used to monitor the recrystallization of the layers. The annealing process induces a displacement of the crystalline-amorphous boundary that is also linear with annealing time, and the recrystallization rates are consistent with those measured for tracks. The comparison of these data with those previously obtained for the heavily damaged (amorphous) layers produced by elastic nuclear collisions is summarily discussed
Diving into the vertical dimension of elasmobranch movement ecology
Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements
The Public Repository of Xenografts enables discovery and randomized phase II-like trials in mice
More than 90% of drugs with preclinical activity fail in human trials, largely due to insufficient efficacy. We hypothesized that adequately powered trials of patient-derived xenografts (PDX) in mice could efficiently define therapeutic activity across heterogeneous tumors. To address this hypothesis, we established a large, publicly available repository of well-characterized leukemia and lymphoma PDXs that undergo orthotopic engraftment, called the Public Repository of Xenografts (PRoXe). PRoXe includes all de-identified information relevant to the primary specimens and the PDXs derived from them. Using this repository, we demonstrate that large studies of acute leukemia PDXs that mimic human randomized clinical trials can characterize drug efficacy and generate transcriptional, functional, and proteomic biomarkers in both treatment-naive and relapsed/refractory disease
Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?
Most Amazonian soils are highly weathered and poor in nutrients. Therefore, photosynthesis and plant growth should positively respond to the addition of mineral nutrients. Surprisingly, no study has been carried out in situ in the central Amazon to address this issue for juvenile trees. The objective of this study was to determine how photosynthetic rates and growth of tree saplings respond to the addition of mineral nutrients, to the variation in leaf area index of the forest canopy, and to changes in soil water content associated with rainfall seasonality. We assessed the effect of adding a slow-release fertilizer. We determined plant growth from 2010 to 2012 and gas exchange in the wet and dry season of 2012. Rainfall seasonality led to variations in soil water content, but it did not affect sapling growth or leaf gas exchange parameters. Although soil amendment increased phosphorus content by 60 %, neither plant growth nor the photosynthetic parameters were influenced by the addition of mineral nutrients. However, photosynthetic rates and growth of saplings decreased as the forest canopy became denser. Even when Amazonian soils are poor in nutrients, photosynthesis and sapling growth are more responsive to slight variations in light availability in the forest understory than to the availability of nutrients. Therefore, the response of saplings to future increases in atmospheric [CO2] will not be limited by the availability of mineral nutrients in the soil
Fine-mapping of prostate cancer susceptibility loci in a large meta-analysis identifies candidate causal variants
Prostate cancer is a polygenic disease with a large heritable component. A number of common, low-penetrance prostate cancer risk loci have been identified through GWAS. Here we apply the Bayesian multivariate variable selection algorithm JAM to fine-map 84 prostate cancer susceptibility loci, using summary data from a large European ancestry meta-analysis. We observe evidence for multiple independent signals at 12 regions and 99 risk signals overall. Only 15 original GWAS tag SNPs remain among the catalogue of candidate variants identified; the remainder are replaced by more likely candidates. Biological annotation of our credible set of variants indicates significant enrichment within promoter and enhancer elements, and transcription factor-binding sites, including AR, ERG and FOXA1. In 40 regions at least one variant is colocalised with an eQTL in prostate cancer tissue. The refined set of candidate variants substantially increase the proportion of familial relative risk explained by these known susceptibility regions, which highlights the importance of fine-mapping studies and has implications for clinical risk profiling. © 2018 The Author(s).Prostate cancer is a polygenic disease with a large heritable component. A number of common, low-penetrance prostate cancer risk loci have been identified through GWAS. Here we apply the Bayesian multivariate variable selection algorithm JAM to fine-map 84 prostate cancer susceptibility loci, using summary data from a large European ancestry meta-analysis. We observe evidence for multiple independent signals at 12 regions and 99 risk signals overall. Only 15 original GWAS tag SNPs remain among the catalogue of candidate variants identified; the remainder are replaced by more likely candidates. Biological annotation of our credible set of variants indicates significant enrichment within promoter and enhancer elements, and transcription factor-binding sites, including AR, ERG and FOXA1. In 40 regions at least one variant is colocalised with an eQTL in prostate cancer tissue. The refined set of candidate variants substantially increase the proportion of familial relative risk explained by these known susceptibility regions, which highlights the importance of fine-mapping studies and has implications for clinical risk profiling. © 2018 The Author(s).Peer reviewe
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