3,469 research outputs found
Emergency Messaging to General Public via Public Wireless Networks
Warnings to the broad population in an emergency situation, irrespective of location and condition, is a public policy responsibility. Public wireless networks offer now the opportunity to deliver emergency warnings in this way with explanations, because in many countries the mobile penetration rates are higher than any other access form .The paper summarizes the analysis of the selection process between Short messaging services (SMS) and Cell Broadcast messaging in the context of Denmark based on end user requirements and stakeholder roles. It demonstrates the many technical, cost-benefit and other trade-offs needed in supporting the population now with a dependable and wide-spread technology.SMS;cell broadcast (CB);emergency warnings;public wireless networks
Eigenmodes of fractal drums: A numerical student experiment
``Can one hear the shape of a drum?'' was a question posed (and made famous)
by mathematician Mark Kac in the mid-1960s. It addresses whether a deeper
connection exists between the resonance modes (eigenmodes) of a drum and its
shape. Here we propose a numerical experiment, suitable for advanced
undergraduate physics students, on the calculation of the eigenmodes of a
square Koch fractal drum, for which experimental results do exist. This
exercise is designed to develop the students' understanding of the vibrations
of fractal drums, their eigenmodes, and potentially their integrated density of
states. The students calculate the lowest order eigenmodes of the fractal drum,
visualize these modes, and study their symmetry properties. As an extension,
the students may investigate the integrated density of states of the fractal
drum and compare their findings to the Weyl-Berry conjecture.Comment: Latex, 9 pages, 5 figure
Vitality and nature in psychiatric spaces: Challenges and prospects for âhealing architectureâ in the design of inpatient mental health environments
Historically, nature has been considered central to healing and recovery in institutional mental health settings, with inpatient spaces designed to mirror the restorative forces nature may afford. Within contemporary healthcare architecture, the discourse surrounding natureâs role has once again become prominent, especially in the concept of âhealing architectureâ. While the literature on âhealing architectureâ primarily considers how to connect recovery to nature through interventions in the built environment, less interest has been directed towards how nature is configured in design processes and what implications that has for the everyday experiences of patients and staff. In this paper we consider the design and implementation of one particular psychiatric hospital in Denmark to show that the ânatureâ brought into this healthcare space can be experienced as anything but ânaturalâ and may reduce rather than enhance a felt sense of âvitalityâ amongst patients. Based on our analysis, we end the paper by suggesting four principles for future healthcare design
Fear and its implications for stock markets
The value of stocks, indices and other assets, are examples of stochastic
processes with unpredictable dynamics. In this paper, we discuss asymmetries in
short term price movements that can not be associated with a long term positive
trend. These empirical asymmetries predict that stock index drops are more
common on a relatively short time scale than the corresponding raises. We
present several empirical examples of such asymmetries. Furthermore, a simple
model featuring occasional short periods of synchronized dropping prices for
all stocks constituting the index is introduced with the aim of explaining
these facts. The collective negative price movements are imagined triggered by
external factors in our society, as well as internal to the economy, that
create fear of the future among investors. This is parameterized by a ``fear
factor'' defining the frequency of synchronized events. It is demonstrated that
such a simple fear factor model can reproduce several empirical facts
concerning index asymmetries. It is also pointed out that in its simplest form,
the model has certain shortcomings.Comment: 5 pages, 5 figures. Submitted to the Proceedings of Applications of
Physics in Financial Analysis 5, Turin 200
Substrate influence on the plasmonic response of clusters of spherical nanoparticles
The plasmonic response of nanoparticles is exploited in many subfields of
science and engineering to enhance optical signals associated with probes of
nanoscale and subnanoscale entities. We develop a numerical algorithm based on
previous theoretical work that addresses the influence of a substrate on the
plasmonic response of collections of nanoparticles of spherical shape. Our
method is a real space approach within the quasi-static limit that can be
applied to a wide range of structures. We illustrate the role of the substrate
through numerical calculations that explore single nanospheres and nanosphere
dimers fabricated from either a Drude model metal or from silver on dielectric
substrates, and from dielectric spheres on silver substrates.Comment: 12 pages, 13 figure
Synchronization Model for Stock Market Asymmetry
The waiting time needed for a stock market index to undergo a given
percentage change in its value is found to have an up-down asymmetry, which,
surprisingly, is not observed for the individual stocks composing that index.
To explain this, we introduce a market model consisting of randomly fluctuating
stocks that occasionally synchronize their short term draw-downs. These
synchronous events are parameterized by a ``fear factor'', that reflects the
occurrence of dramatic external events which affect the financial market.Comment: 4 pages, 4 figure
Design of one-dimensional Lambertian diffusers of light
We describe a method for designing a one-dimensional random surface that acts
as a Lambertian diffuser. The method is tested by means of rigorous computer
simulations and is shown to yield the desired scattering pattern.Comment: 6 pages, 2 figure
Emergency Messaging to General Public via Public Wireless Networks
Warnings to the broad population in an emergency situation, irrespective of location and condition, is a public policy responsibility. Public wireless networks offer now the opportunity to deliver emergency warnings in this way with explanations, because in many countries the mobile penetration rates are higher than any other access form .The paper summarizes the analysis of the selection process between Short messaging services (SMS) and Cell Broadcast messaging in the context of Denmark based on end user requirements and stakeholder roles. It demonstrates the many technical, cost-benefit and other trade-offs needed in supporting the population now with a dependable and wide-spread technology
Single scattering of polarized light by correlated surface and volume disorder
We study light scattering by systems combining randomly rough surface and
volume dielectric fluctuations. We introduce a general model including
correlations between surface and volume disorders, and we study the scattering
properties within a single scattering approach. We identify different regimes
of surface and volume dominated scattering depending on length scales
characterizing the surface and volume disorders. For uncorrelated disorders, we
discuss the polarization response of each source of disorder, and show how
polarimetric measurements can be used to separate the surface and volume
contributions in the total measured diffusely scattered intensity. For
correlated systems, we identify two configurations of volume disorder which,
respectively, couple weakly or strongly to surface scattering via
surface-volume cross-correlations. We illustrate these effects on different
configurations exhibiting interference patterns in the diffusely scattered
intensity, which may be of interest for the characterization of complex systems
or for the design of optical components by engineering the degree of
surface-volume correlations.Comment: 25 pages, 22 figure
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