8,963 research outputs found
MSUO Information Technology and Geographical Information Systems: Common Protocols & Procedures. Report to the Marine Safety Umbrella Operation
The Marine Safety Umbrella Operation (MSUO) facilitates the cooperation between Interreg
funded Marine Safety Projects and maritime stakeholders. The main aim of MSUO is to
permit efficient operation of new projects through Project Cooperation Initiatives, these
include the review of the common protocols and procedures for Information Technology (IT)
and Geographical Information Systems (GIS).
This study carried out by CSA Group and the National Centre for Geocomputation (NCG)
reviews current spatial information standards in Europe and the data management
methodologies associated with different marine safety projects.
International best practice was reviewed based on the combined experience of spatial data
research at NCG and initiatives in the US, Canada and the UK relating to marine security
service information and acquisition and integration of large marine datasets for ocean
management purposes.
This report identifies the most appropriate international data management practices that could
be adopted for future MSUO projects
Evidence in Practice – A Pilot Study Leveraging Companion Animal and Equine Health Data from Primary Care Veterinary Clinics in New Zealand
Veterinary practitioners have extensive knowledge of animal health from their day-to-day observations of clinical patients. There have been several recent initiatives to capture these data from electronic medical records for use in national surveillance systems and clinical research. In response, an approach to surveillance has been evolving that leverages existing computerized veterinary practice management systems to capture animal health data recorded by veterinarians. Work in the United Kingdom within the VetCompass program utilizes routinely recorded clinical data with the addition of further standardized fields. The current study describes a prototype system that was developed based on this approach. In a 4-week pilot study in New Zealand, clinical data on presentation reasons and diagnoses from a total of 344 patient consults were extracted from two veterinary clinics into a dedicated database and analyzed at the population level. New Zealand companion animal and equine veterinary practitioners were engaged to test the feasibility of this national practice-based health information and data system. Strategies to ensure continued engagement and submission of quality data by participating veterinarians were identified, as were important considerations for transitioning the pilot program to a sustainable large-scale and multi-species surveillance system that has the capacity to securely manage big data. The results further emphasized the need for a high degree of usability and smart interface design to make such a system work effectively in practice. The geospatial integration of data from multiple clinical practices into a common operating picture can be used to establish the baseline incidence of disease in New Zealand companion animal and equine populations, detect unusual trends that may indicate an emerging disease threat or welfare issue, improve the management of endemic and exotic infectious diseases, and support research activities. This pilot project is an important step toward developing a national surveillance system for companion animals and equines that moves beyond emerging infectious disease detection to provide important animal health information that can be used by a wide range of stakeholder groups, including participating veterinary practices
Mean curvature flow and quasilocal mass for two-surfaces in Hamiltonian General Relativity
A family of quasilocal mass definitions that includes as special cases the
Hawking mass and the Brown-York ``rest mass'' energy is derived for spacelike
2-surfaces in spacetime. The definitions involve an integral of powers of the
norm of the spacetime mean curvature vector of the 2-surface, whose properties
are connected with apparent horizons. In particular, for any spacelike
2-surface, the direction of mean curvature is orthogonal (dual in the normal
space) to a unique normal direction in which the 2-surface has vanishing
expansion in spacetime. The quasilocal mass definitions are obtained by an
analysis of boundary terms arising in the gravitational ADM Hamiltonian on
hypersurfaces with a spacelike 2-surface boundary, using a geometric time-flow
chosen proportional to the dualized mean curvature vector field at the boundary
surface. A similar analysis is made choosing a geometric rotational flow given
in terms of the twist covector of the dual pair of mean curvature vector
fields, which leads to a family of quasilocal angular momentum definitions
involving the squared norm of the twist. The large sphere limit of these
definitions is shown to yield the ADM mass and angular momentum in
asymptotically flat spacetimes, while at apparent horizons a quasilocal version
of the Gibbons-Penrose inequality is derived. Finally, some results concerning
positivity are proved for the quasilocal masses, motivated by consideration of
spacelike mean curvature flow of 2-surfaces in spacetime.Comment: Revised version, includes an analysis of null flows with applications
to mass and angular momentum for apparent horizon
Limit curve theorems in Lorentzian geometry
The subject of limit curve theorems in Lorentzian geometry is reviewed. A
general limit curve theorem is formulated which includes the case of converging
curves with endpoints and the case in which the limit points assigned since the
beginning are one, two or at most denumerable. Some applications are
considered. It is proved that in chronological spacetimes, strong causality is
either everywhere verified or everywhere violated on maximizing lightlike
segments with open domain. As a consequence, if in a chronological spacetime
two distinct lightlike lines intersect each other then strong causality holds
at their points. Finally, it is proved that two distinct components of the
chronology violating set have disjoint closures or there is a lightlike line
passing through each point of the intersection of the corresponding boundaries.Comment: 25 pages, 1 figure. v2: Misprints fixed, matches published versio
Microwave oven fabricated hybrid memristor devices for non-volatile memory storage
© 2014 IOP Publishing Ltd. Novel hybrid non-volatile memories made using an ultra-fast microwave heating method are reported for the first time. The devices, consisting of aligned ZnO nanorods embedded in poly (methyl methacrylate), require no forming step and exhibit reliable and reproducible bipolar resistive switching at low voltages and with low power usage. We attribute these properties to a combination of the high aspect ratio of the nanorods and the polymeric hybrid structure of the device. The extremely easy, fast and low-cost solution based method of fabrication makes possible the simple and quick production of cheap memory cells
Magnification relations for Kerr lensing and testing Cosmic Censorship
A Kerr black hole with mass parameter m and angular momentum parameter a
acting as a gravitational lens gives rise to two images in the weak field
limit. We study the corresponding magnification relations, namely the signed
and absolute magnification sums and the centroid up to post-Newtonian order. We
show that there are post-Newtonian corrections to the total absolute
magnification and centroid proportional to a/m, which is in contrast to the
spherically symmetric case where such corrections vanish. Hence we also propose
a new set of lensing observables for the two images involving these
corrections, which should allow measuring a/m with gravitational lensing. In
fact, the resolution capabilities needed to observe this for the Galactic black
hole should in principle be accessible to current and near-future
instrumentation. Since a/m >1 indicates a naked singularity, a most interesting
application would be a test of the Cosmic Censorship conjecture. The technique
used to derive the image properties is based on the degeneracy of the Kerr lens
and a suitably displaced Schwarzschild lens at post-Newtonian order. A simple
physical explanation for this degeneracy is also given.Comment: 13 pages, version 2: references added, minor changes. To appear in
Phys. Rev.
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Pricing in Day-Ahead Electricity Markets with Near-Optimal Unit Commitment
This paper revisits some peculiar pricing properties of near-optimal unit commitment solutions. Previous work has found that prices can behave erratically even as unit commitment solutions approach the optimal solution, resulting in potentially large wealth transfers due to suboptimality of the solution. Our analysis considers how recently proposed pricing models affect this behavior. Results demonstrate a previously unknown property of one of these pricing models, called approximate Convex Hull Pricing (aCHP), that eliminates erratic price behavior, and therefore limits wealth transfers with respect to the optimal unit commitment solution. The absence of wealth transfers may imply fewer strategic bidding incentives, which could enhance market efficiency
Experimental Polarization State Tomography using Optimal Polarimeters
We report on the experimental implementation of a polarimeter based on a
scheme known to be optimal for obtaining the polarization vector of ensembles
of spin-1/2 quantum systems, and the alignment procedure for this polarimeter
is discussed. We also show how to use this polarimeter to estimate the
polarization state for identically prepared ensembles of single photons and
photon pairs and extend the method to obtain the density matrix for generic
multi-photon states. State reconstruction and performance of the polarimeter is
illustrated by actual measurements on identically prepared ensembles of single
photons and polarization entangled photon pairs
Wave-number Selection by Target Patterns and Side Walls in Rayleigh-Benard Convection
We present experimental results for Rayleigh-Benard convection patterns in a
cylindrical container with static side-wall forcing induced by a heater. This
forcing stabilized a pattern of concentric rolls (a target pattern) with the
central roll (the umbilicus) at the center of the cell after a jump from the
conduction to the convection state. A quasi-static increase of the control
parameter (epsilon) beyond 0.8 caused the umbilicus of the pattern to move off
center. As observed by others, a further quasi-static increase of epsilon up to
15.6 caused a sequence of transitions. Each transition began with the
displacement of the umbilicus and then proceeded with the loss of one
convection roll at the umbilicus and the return of the umbilicus to a location
near the center of the cell. Alternatively, with decreasing epsilon new rolls
formed at the umbilicus but large umbilicus displacements did not occur. In
addition to quantitative measurements of the umbilicus displacement, we
determined and analyzed the entire wave-director field of each image. The wave
numbers varied in the axial direction, with minima at the umbilicus and at the
cell wall and a maximum at a radial position close to 2/3 Gamma. The wave
numbers at the maximum showed hysteretic jumps at the transitions, but on
average agreed well with the theoretical predictions for the wave numbers
selected in the far field of an infinitely extended target pattern.Comment: ReVTeX, 11 pages, 16 eps figures include
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