478 research outputs found
Two Centuries of Farmland Prices in England
The dissemination of robust real estate data can help to improve market efficiency and investment analysis. To provide a perspective on property prices, a long series is vital. While long commercial and residential real estate data series are available, agricultural land is less well served. Comparable series describing long-term price and return histories for farmland in England are fragmented. We redress this data deficiency after considering the methodological complexities involved. The study employs a chain-linking approach to construct a long-term farmland price series for England. It then adjusts the series for inflation to examine real land prices. The resulting two-century series of English farmland prices establishes a basis for a more efficient farmland market analysis.
Notwithstanding issues around long-run chain component heterogeneity, the combined series illuminates English average farmland price dynamics and changing land market fortunes. For more than two centuries English land price real capital returns were positive. Farmland real price growth was 0.33 per cent annually from 1781 to 2013 and 0.71 per cent from 1801 to 2013 as measured by the geometric mean. The series provides prima facie support for land investment, even when ignoring spatial peri-urban opportunities, rental income or tax advantages
Mitigating sampling error when measuring internet client IPv6 capabilities
Despite the predicted exhaustion of unallocated IPv4 addresses be- tween 2012 and 2014, it remains unclear how many current clients can use its successor, IPv6, to access the Internet. We propose a refinement of previous measurement studies that mitigates intrin- sic measurement biases, and demonstrate a novel web-based tech- nique using Google ads to perform IPv6 capability testing on a wider range of clients. After applying our sampling error reduction, we find that 6% of world-wide connections are from IPv6-capable clients, but only 1–2% of connections preferred IPv6 in dual-stack (dual-stack failure rates less than 1%). Except for an uptick around IPv6-day 2011 these proportions were relatively constant, while the percentage of connections with IPv6-capable DNS resolvers has in- creased to nearly 60%. The percentage of connections from clients with native IPv6 using happy eyeballs has risen to over 20
A comparative analysis of parallel processing and super-individual methods for improving the computational performance of a large individual-based model
Individual-based modelling approaches are being used to simulate larger complex spatial systems in ecology and in other fields of research. Several novel model development issues now face researchers: in particular how to simulate large numbers of individuals with high levels of complexity, given finite computing resources. A case study of a spatially-explicit simulation of aphid population dynamics was used to assess two strategies for coping with a large number of individuals: the use of ‘super-individuals’ and parallel computing. Parallelisation of the model maintained the model structure and thus the simulation results were comparable to the original model. However, the super-individual implementation of the model caused significant changes to the model dynamics, both spatially and temporally. When super-individuals represented more than around 10 individuals it became evident that aggregate statistics generated from a super-individual model can hide more detailed deviations from an individual-level model. Improvements in memory use and model speed were perceived with both approaches. For the parallel approach, significant speed-up was only achieved when more than five processors were used and memory availability was only increased once five or more processors were used. The super-individual approach has potential to improve model speed and memory use dramatically, however this paper cautions the use of this approach for a density-dependent spatially-explicit model, unless individual variability is better taken into account
Bayesian Physics Informed Neural Networks for Data Assimilation and Spatio-Temporal Modelling of Wildfires
We apply the Physics Informed Neural Network (PINN) to the problem of
wildfire fire-front modelling. We use the PINN to solve the level-set equation,
which is a partial differential equation that models a fire-front through the
zero-level-set of a level-set function. The result is a PINN that simulates a
fire-front as it propagates through the spatio-temporal domain. We show that
popular optimisation cost functions used in the literature can result in PINNs
that fail to maintain temporal continuity in modelled fire-fronts when there
are extreme changes in exogenous forcing variables such as wind direction. We
thus propose novel additions to the optimisation cost function that improves
temporal continuity under these extreme changes. Furthermore, we develop an
approach to perform data assimilation within the PINN such that the PINN
predictions are drawn towards observations of the fire-front. Finally, we
incorporate our novel approaches into a Bayesian PINN (B-PINN) to provide
uncertainty quantification in the fire-front predictions. This is significant
as the standard solver, the level-set method, does not naturally offer the
capability for data assimilation and uncertainty quantification. Our results
show that, with our novel approaches, the B-PINN can produce accurate
predictions with high quality uncertainty quantification on real-world data.Comment: Accepted for publication in Spatial Statistic
Therapeutic potential of HMGB1-targeting agents in sepsis
Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial
infection. The inflammatory response is partly mediated by innate immune cells (such as
macrophages, monocytes and neutrophils), which not only ingest and eliminate invading
pathogens but also initiate an inflammatory response upon recognition of
pathogen-associated molecular patterns (PAMPs). The prevailing theories of sepsis as a
dysregulated inflammatory response, as manifested by excessive release of inflammatory
mediators such as tumour necrosis factor and high-mobility group box 1 protein (HMGB1),
are supported by extensive studies employing animal models of sepsis. Here we review
emerging evidence that support extracellular HMGB1 as a late mediator of experimental
sepsis, and discuss the therapeutic potential of several HMGB1-targeting agents (including
neutralising antibodies and steroid-like tanshinones) in experimental sepsis
Geographic and Sociodemographic Disparities in Drive Times to Joint Commission–Certified Primary Stroke Centers in North Carolina, South Carolina, and Georgia
Introduction: Timely access to facilities that provide acute stroke care is necessary to reduce disabilities and death from stroke. We examined geographic and sociodemographic disparities in drive times to Joint Commission–certified primary stroke centers (JCPSCs) and other hospitals with stroke care quality improvement initiatives in North Carolina, South Carolina, and Georgia. Methods: We defined boundaries for 30- and 60-minute drive-time areas to JCPSCs and other hospitals by using geographic information systems (GIS) mapping technology and calculated the proportions of the population living in these drive-time areas by sociodemographic characteristics. Age-adjusted county-level stroke death rates were overlaid onto the drive-time areas. Results: Approximately 55% of the population lived within a 30-minute drive time to a JCPSC; 77% lived within a 60-minute drive time. Disparities in percentage of the population within 30-minute drive times were found by race/ethnicity, education, income, and urban/rural status; the disparity was largest between urban areas (70% lived within 30-minute drive time) and rural areas (26%). The rural coastal plains had the largest concentration of counties with high stroke death rates and the fewest JCPSCs. Conclusion: Many areas in this tri-state region lack timely access to JCPSCs. Alternative strategies are needed to expand provision of quality acute stroke care in this region. GIS modeling is valuable for examining and strategically planning the distribution of hospitals providing acute stroke care
RoSETZ: Roman Survey of the Earth Transit Zone -- a SETI-optimized survey for habitable-zone exoplanets
In this White Paper for Nancy Grace Roman Space Telescope (Roman) science, we
propose the Roman Survey of the Earth Transit Zone (RoSETZ), a transit search
for rocky planets within the habitable zones (HZs) of stars located within the
Earth Transit Zone (ETZ). The ETZ holds special interest in the search for
extra-terrestrial intelligence (SETI) - observers on planets within the ETZ can
see Earth as a transiting planet. RoSETZ would augment the Roman Galactic Bulge
Time Domain Survey (GBTDS) as an additional field located ~degrees away
from other GBTDS fields. Our simulations show that RoSETZ alone can find from
120 to 630 Earth-sized HZ planets around K- and M-type hosts, with the range
reflecting different survey design assumptions. These yields are 5-20 times the
number currently known. Such a sample will transform our knowledge of
``Eta-Earth'' () -- the occurrence of Earth-sized HZ planets --
and would be the first catalogue of exoplanets selected in a manner optimized
according to the Mutual Detectability targetted-SETI strategy. If it can be
accommodated alongside the existing GBTDS design, we favour a RoSETZ-Max design
that is observed for the duration of the GBTDS. If not, we show that a
slimmed-down RoSETZ-Lite design, occupying two GBTDS seasons, would not
significantly impact overall GBTDS exoplanet yields, even if time allocated to
it had to come from time allocations to other fields. We argue that the angular
separation of RoSETZ from other GBTDS fields permits self-calibration of
systematic uncertainties that would otherwise hamper exoplanet demographic
modelling of both microlensing and transit datasets. Other science possible
with RoSETZ data include studies of small solar system bodies and high
resolution 3D extinction mapping.Comment: 20 pages. Submission to the NASA Roman Core Community Surveys White
Paper Cal
Riots and reform: burgh authority, the languages of civic reform and the Aberdeen riot of 1785
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