47,168 research outputs found
A commentary on recent water safety initiatives in the context of water utility risk management.
Over the last decade, suppliers of drinking water have recognised the
limitations of relying solely on end-product monitoring to ensure safe water
quality and have sought to reinforce their approach by adopting preventative
strategies where risks are proactively identified, assessed and managed. This is
leading to the development of water safety plans; structured ‘route maps’ for
managing risks to water supply, from catchment to consumer taps. This paper
reviews the Hazard Analysis and Critical Control Point (HACCP) procedure on
which many water safety plans are based and considers its appropriateness in the
context of drinking water risk management. We examine water safety plans in a
broad context, looking at a variety of monitoring, optimisation and risk
management initiatives that can be taken to improve drinking water safety. These
are cross-compared using a simple framework that facilitates an integrated
approach to water safety. Finally, we look at how risk management practices are
being integrated across water companies and how this is likely to affect the
future development of water safety p
Evolutionary Divergence in Developmental Strategies and Neuromodulatory Control Systems of Two Amphibian Locomotor Networks
Attempts to understand the neural mechanisms which produce behaviour must consider both prevailing sensory cues and the central cellular and synaptic changes they direct. At each level, neuromodulation can additionally shape the final output. We have investigated neuromodulation in the developing spinal motor networks in hatchling tadpoles of two closely related amphibians, Xenopus laevis and Rana temporaria to examine the subtle differences in their behaviours that could be attributed to their evolutionary divergence.
At the point of hatching, both species can swim in response to a mechanosensory stimulus, however Rana embryos often display a more forceful, non-locomotory coiling behaviour. Whilst the synaptic drive that underlies these behaviours appears similar, subtle inter-specific differences in neuronal properties shape motor outputs in different ways. For example, Rana neurons express N-methyl-D-aspartate (NMDA)/serotonin (5-HT)-dependent oscillations, not present in hatchling Xenopus and many also exhibit a prominent slow spike after-hyperpolarisation. Such properties may endow the spinal circuitry of Rana with the ability to produce a more flexible range of outputs.
Finally, we compare the roles of the neuromodulators 5-HT, noradrenaline (NA) and nitric oxide (NO) in shaping motor outputs. 5-HT increases burst durations during swimming in both Xenopus and Rana, but 5-HT dramatically slows the cycle period in Rana with little effect in Xenopus. Three distinct, but presumably homologous NO-containing brainstem clusters of neurons have been described, yet the effects of NO differ between species. In Xenopus, NO slows and shortens swimming in a manner similar to NA, yet in Rana NO and NA elicit the non-rhythmic coiling pattern
Integrating Research Data Management into Geographical Information Systems
Ocean modelling requires the production of high-fidelity computational meshes
upon which to solve the equations of motion. The production of such meshes by
hand is often infeasible, considering the complexity of the bathymetry and
coastlines. The use of Geographical Information Systems (GIS) is therefore a
key component to discretising the region of interest and producing a mesh
appropriate to resolve the dynamics. However, all data associated with the
production of a mesh must be provided in order to contribute to the overall
recomputability of the subsequent simulation. This work presents the
integration of research data management in QMesh, a tool for generating meshes
using GIS. The tool uses the PyRDM library to provide a quick and easy way for
scientists to publish meshes, and all data required to regenerate them, to
persistent online repositories. These repositories are assigned unique
identifiers to enable proper citation of the meshes in journal articles.Comment: Accepted, camera-ready version. To appear in the Proceedings of the
5th International Workshop on Semantic Digital Archives
(http://sda2015.dke-research.de/), held in Pozna\'n, Poland on 18 September
2015 as part of the 19th International Conference on Theory and Practice of
Digital Libraries (http://tpdl2015.info/
Morbidity Pattern and its Determinants among Tribal People in Kerala
While Kerala has been hailed for its development in social sectors, the available data show the remarkable finding that Kerala’s morbidity is the highest in India. Literature reveals two major streams of argument for this, one questioning the comparability of the reported rates of morbidity and the other admitting that the higher rates of morbidity actually represent the situation. The present study analyses the pattern of morbidity in Kerala, tries to analyse the morbidity pattern and finds out the reasons for highest morbidity in highest Monthly Per Capita Consumption Expenditure (MPCE) group and lower morbidity in ST households. The paper argues that the prevalence of lifestyle diseases among highest MPCE group is one critical reason for the high morbidity rates in Kerala. It also proposes urgent interventions on behalf of the government that can effectively counter the high rates of infectious diseases among ST households
Mean eigenvalues for simple, simply connected, compact Lie groups
We determine for each of the simple, simply connected, compact and complex
Lie groups SU(n), Spin and that particular region inside the unit
disk in the complex plane which is filled by their mean eigenvalues. We give
analytical parameterizations for the boundary curves of these so-called trace
figures. The area enclosed by a trace figure turns out to be a rational
multiple of in each case. We calculate also the length of the boundary
curve and determine the radius of the largest circle that is contained in a
trace figure. The discrete center of the corresponding compact complex Lie
group shows up prominently in the form of cusp points of the trace figure
placed symmetrically on the unit circle. For the exceptional Lie groups ,
and with trivial center we determine the (negative) lower bound on
their mean eigenvalues lying within the real interval . We find the
rational boundary values -2/7, -3/13 and -1/31 for , and ,
respectively.Comment: 12 pages, 8 figure
Dispersion and fidelity in quantum interferometry
We consider Mach-Zehnder and Hong-Ou-Mandel interferometers with nonclassical
states of light as input, and study the effect that dispersion inside the
interferometer has on the sensitivity of phase measurements. We study in detail
a number of different one- and two-photon input states, including Fock, dual
Fock, N00N states, and photon pairs from parametric downconversion. Assuming
there is a phase shift in one arm of the interferometer, we compute
the probabilities of measurement outcomes as a function of , and then
compute the Shannon mutual information between and the measurements.
This provides a means of quantitatively comparing the utility of various input
states for determining the phase in the presence of dispersion. In addition, we
consider a simplified model of parametric downconversion for which
probabilities can be explicitly computed analytically, and which serves as a
limiting case of the more realistic downconversion model.Comment: 12 pages, 14 figures. Submitted to Physical Review
Improving the worthiness of the Elder problem as a benchmark for buoyancy driven convection models
An important trapping mechanism associated with the geosequestration of CO~2~ is that of dissolution into the formation water. Although supercritical CO~2~ is significantly less dense than water, experimental data reported in the literature show that the density of an aqueous solution of CO~2~ could be slightly greater. Under normal situations, the transfer of gas to solution is largely controlled by the relatively slow process of molecular diffusion. However, the presence of variable densities can trigger off gravity instabilities leading to much larger-scale convection processes. Such processes can potentially enhance rates of dissolution by an order of magnitude. Consequently there is a need for future performance assessment models to incorporate buoyancy driven convection (BDC). A major issue associated with BDC models is that of grid convergence when benchmarking to the Elder problem. The Elder problem originates from a heat convection experiment whereby a rectangular Hele-Shaw cell was heated over the central half of its base. A quarter of the way through the experiment, Elder (1967) observed six plumes, with four narrow plumes in the center and two larger plumes at the edges. As the experiment progressed, only four plumes remained. The issue is that depending on the grid resolution used when seeking to model this problem, modelers have found that different schemes yield steady states with either one, two or three plumes. The aim of this paper is to clarify and circumvent the issue of multiple steady state solutions in the Elder problem using a pseudospectral method
On spectrum of a Schroedinger operator with a fast oscillating compactly supported potential
We study the phenomenon of an eigenvalue emerging from essential spectrum of
a Schroedinger operator perturbed by a fast oscillating compactly supported
potential. We prove the sufficient conditions for the existence and absence of
such eigenvalue. If exists, we obtain the leading term of its asymptotics
expansion.Comment: The article is originally written in Russian. The translation in
English is made by D. Boriso
A predictive model of energy savings from top of rail friction control
In this paper the authors present a predictive model of train energy requirements due to the application of a top of rail friction modifier (TOR-FM) versus dry wheel / rail conditions. Using the VAMPIRE® Pro simulation package, train energy requirements are modeled for two sets of TOR-FM frictional conditions, one using full Kalker coefficients and the other by using a Kalker factor of 18%. Both scenarios use a top of rail saturated coefficient of friction of 0.35. Under both TOR-FM frictional conditions, train energy savings are shown for complete laps of the Transportation Technology Center Inc.’s (TTCI) Transit Test Track (TTT) loop, and also when isolating only the tangent section of the loop. However, the magnitude of energy savings varies greatly depending on the Kalker coefficient factor used, highlighting the need to model this relationship as accurately as possible. These simulation results are compared with data obtained from a field study, in which train energy savings of 5.3% (lap) and 7.8% (tangent) are shown due to the application of TOR-FM
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