3,519 research outputs found
Deploying rural community wireless mesh networks
Inadequate Internet access is widening the digital divide between town and countryside, degrading both social communication and business advancements in rural areas. Wireless mesh networking can provide an excellent framework
for delivering broadband services to such areas. With this in mind, Lancaster University deployed a WMN in the rural village of Wray over a three-year period, providing the community with Internet service that exceeds many urban offerings. The project gave researchers a real-world testbed for exploring the technical and social issues entailed in deploying WMNs in the heart of a small community
The impact of transport infrastructure projects on sustainable development within a major logistics gateway in North West England
In the North West of England the issue of a perceived infrastructure gap is of increasing concern. Investment needs to be made to improve the transport infrastructure of the region if it is to be expected to promote the development of its own regional logistics gateway. Funding tools have been set up to address the challenges arising from the imbalance in infrastructure development that exists between regions in the north of the United Kingdom and those in the south. For regions with well developed economies the outlook is promising as the availability of modern transport infrastructure looks set to improve. However, some sources believe that the development of new transport infrastructure will have a negative impact upon sustainable development. It is expected that this will occur in a range of both direct and indirect ways. As a result, it is critical that planning for the creation of new intermodal transport infrastructure, or the upgrading of that which already exists, takes into account the impact that these developments will have on the sustainable development of the host region. A scenario based development methodology is proposed in this paper. It was developed to provide a way to identify potential scenarios that may arise within a given region as a result of transport infrastructure projects. To create significant scenarios the methodology is dependent on the availability of a sufficient quantity of quality data. For this paper that data was collected through a focus group composed of stakeholders from the region in question. This was further supported by the performance of an impact survey using the same group of stakeholders
Characterizing contributions of glacier melt and groundwater during the dry season in a poorly gauged catchment of the Cordillera Blanca (Peru)
The retreat of glaciers in the tropics will have a significant impact on water resources. In order to overcome limitations with discontinuous to nonexistent hydrologic measurements in remote mountain watersheds, a hydrochemical and isotopic mass balance model is used to identify and characterize dry season water origins at the glacier fed Querococha basin located in southern Cordillera Blanca, Peru. Dry season water samples, collected intermittently between 1998 and 2007, were analyzed for major ions and the stable isotopes of water (ÎŽ^18 O and ÎŽ^2 H). The hydrochemical and isotopic data are analysed using conservative characteristics of selected tracers and relative contributions are calculated based on pre-identified contributing sources at mixing points sampled across the basin. The results show that during the dry-season, groundwater is the largest contributor to basin outflow and that the flux of groundwater is temporally variable. The groundwater contribution significantly correlates (P-value=0.004 to 0.044) to the antecedent precipitation regime at 3 and 18â36 months. Assuming this indicates a maximum of 4 years of precipitation accumulation in groundwater reserves, the Querococha watershed outflows are potentially vulnerable to multi-year droughts and climate related changes in the precipitation regime. The results show that the use of hydrochemical and isotopic data can contribute to hydrologic studies in remote, data poor regions, and that groundwater contribution to tropical proglacial hydrologic systems is a critical component of dry season discharge
The Role of the Prefrontal Cortex and Functional Connectivity during Maritime Operations: An fNIRS study
Introduction: Watchkeeping is a significant activity during maritime operations, and failures of sustained attention and decisionâmaking can increase the likelihood of a collision.
Methods: A study was conducted in a ship bridge simulator where 40 participants (20 experienced/20 inexperienced) performed: (1) a 20âmin period of sustained attention to locate a target vessel and (2) a 10âmin period of decisionâmaking/action selection to perform an evasive maneuver. Half of the participants also performed an additional task of verbally reporting the position of their vessel. Activation of the prefrontal cortex (PFC) was captured via a 15âchannel functional nearâinfrared spectroscopy (fNIRS) montage, and measures of functional connectivity were calculated frontal using graphâtheoretic measures.
Results: Neurovascular activation of right lateral area of the PFC decreased during sustained attention and increased during decisionâmaking. The graphâtheoretic analysis revealed that density declined during decisionâmaking in comparison with the previous period of sustained attention, while local clustering declined during sustained attention and increased when participants prepared their evasive maneuver. A regression analysis revealed an association between network measures and behavioral outcomes, with respect to spotting the target vessel and making an evasive maneuver.
Conclusions: The right lateral area of the PFC is sensitive to watchkeeping and decisionâmaking during operational performance. Graphâtheoretic measures allow us to quantify patterns of functional connectivity and were predictive of safetyâcritical performance
'A light in a very dark place' : The role of a voluntary organisation providing support for those affected by encephalitis
Voluntary organisations are seen as contributing to the âdemocratisationâ of health and social care. Little, however, is written about their role and this paper, by focusing on the work of The Encephalitis Society, provides insights into the challenges facing voluntary organisations as they manage twin roles as service providers and advocates, of people with neurological disorders. Two studies are presented: a review conducted by the Society, focusing on patientâs experiences of neurological services; and an external evaluation of the Societyâs current provision. The first, based on a postal survey of its members affected by encephalitis (n = 339), illustrates the Societyâs advocacy role. The survey provided support for the Association of British Neurologistsâ recommendation for nationally agreed standards of care. The second study, a postal survey of recent contacts (n = 76) and in-depth telephone interviews (n = 22), illustrates the Societyâs value role as a service provider and supports its role in helping rehabilitate affected individuals and their families. These studies provided the Society with information for policy and service development. Importantly, providing the basis of informed action and partnership with stakeholders and informing the organisationâs sense of purpose, in the changing context of welfare provision in the UK
Statistical pairwise interaction model of stock market
Financial markets are a classical example of complex systems as they comprise
many interacting stocks. As such, we can obtain a surprisingly good description
of their structure by making the rough simplification of binary daily returns.
Spin glass models have been applied and gave some valuable results but at the
price of restrictive assumptions on the market dynamics or others are
agent-based models with rules designed in order to recover some empirical
behaviours. Here we show that the pairwise model is actually a statistically
consistent model with observed first and second moments of the stocks
orientation without making such restrictive assumptions. This is done with an
approach based only on empirical data of price returns. Our data analysis of
six major indices suggests that the actual interaction structure may be thought
as an Ising model on a complex network with interaction strengths scaling as
the inverse of the system size. This has potentially important implications
since many properties of such a model are already known and some techniques of
the spin glass theory can be straightforwardly applied. Typical behaviours, as
multiple equilibria or metastable states, different characteristic time scales,
spatial patterns, order-disorder, could find an explanation in this picture.Comment: 11 pages, 8 figure
U.S. stock market interaction network as learned by the Boltzmann Machine
We study historical dynamics of joint equilibrium distribution of stock
returns in the U.S. stock market using the Boltzmann distribution model being
parametrized by external fields and pairwise couplings. Within Boltzmann
learning framework for statistical inference, we analyze historical behavior of
the parameters inferred using exact and approximate learning algorithms. Since
the model and inference methods require use of binary variables, effect of this
mapping of continuous returns to the discrete domain is studied. The presented
analysis shows that binarization preserves market correlation structure.
Properties of distributions of external fields and couplings as well as
industry sector clustering structure are studied for different historical dates
and moving window sizes. We found that a heavy positive tail in the
distribution of couplings is responsible for the sparse market clustering
structure. We also show that discrepancies between the model parameters might
be used as a precursor of financial instabilities.Comment: 15 pages, 17 figures, 1 tabl
Moral dilemmas and abortion decision-making: Lessons learnt from abortion research in England and Wales
This paper scrutinises the concepts of moral reasoning and personal reasoning, problematising the binary model by looking at young women's pregnancy decision-making. Data from two UK empirical studies are subjected to theoretically driven qualitative secondary analysis, and illustrative cases show how complex decision-making is characterised by an intertwining of the personal and the moral, and is thus best understood by drawing on moral relativism
Magnetic fluctuations in the classical XY model: the origin of an exponential tail in a complex system
We study the probability density function for the fluctuations of the
magnetic order parameter in the low temperature phase of the XY model of finite
size. In two-dimensions this system is critical over the whole of the low
temperature phase. It is shown analytically and without recourse to the scaling
hypothesis that, in this case, the distribution is non-Gaussian and of
universal form, independent of both system size and critical exponent .
An exact expression for the generating function of the distribution is
obtained, which is transformed and compared with numerical data from high
resolution molecular dynamics and Monte Carlo simulations. The calculation is
extended to general dimension and an exponential tail is found in all
dimensions less than four, despite the fact that critical fluctuations are
limited to D=2. These results are discussed in the light of similar behaviour
observed in models of interface growth and for dissipative systems driven into
a non-equilibrium steady state.Comment: 32 pages, 13 figures, 1 table. Few changes. To appear in Phys. Rev.
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