4,322 research outputs found
The Common Cold, Influenza and Immunity in Post-Pandemic Times: Lay representations of Self and Other among older people in Sweden
The need for new knowledge about lay representations of contagions, immunity, vaccination, common colds, and influenza has become clear after the A(H1N1) pandemic and the resulting challenges regarding pandemic preparedness. This article analyses written responses from 67 persons, mostly women, to a semi-structured questionnaire about colds and the flu. Three themes are discussed: “Common cold and flus as ritualized experiences”, “Me, my body, and my immune defense”, and “Regulations of space, place, and behaviors.” Overall, the narratives were about trust, value, and respect in the body, in lived experiences, and in the capacity to ‘help’ and ‘nurture’ the immune system, but also about the feeling of powerlessness when perceiving inadequacies in other people’s parallel interpretations and actions. Pandemic preparedness policies need to acknowledge the multiple ‘immunity talk’ in the responses to create productive, ongoing relations with the ‘Other’, that rely on people’s trust and resilience, rather than on people´s fear
Finite Mirror Effects in Advanced Interferometric Gravitational Wave Detectors
Thermal noise is expected to be the dominant source of noise in the most
sensitive frequency band of second generation ground based gravitational wave
detectors. Reshaping the beam to a flatter wider profile which probes more of
the mirror surface reduces this noise. The "Mesa" beam shape has been proposed
for this purpose and was subsequently generalized to a family of hyperboloidal
beams with two parameters: twist angle alpha and beam width D. Varying alpha
allows a continuous transition from the nearly-flat to the nearly-concentric
Mesa beam configurations. We analytically prove that in the limit of infinite D
hyperboloidal beams become Gaussians. The Advanced LIGO diffraction loss design
constraint is 1 ppm per bounce. In the past the diffraction loss has often been
calculated using the clipping approximation that, in general, underestimates
the diffraction loss. We develop a code using pseudo-spectral methods to
compute the diffraction loss directly from the propagator. We find that the
diffraction loss is not a strictly monotonic function of beam width, but has
local minima that occur due to finite mirror effects and leads to natural
choices of D. For the Mesa beam a local minimum occurs at D = 10.67 cm and
leads to a diffraction loss of 1.4 ppm. We find that if one requires a
diffraction loss of strictly 1 ppm, the alpha = 0.91 pi hyperboloidal beam is
optimal, leading to the coating thermal noise being lower by about 10% than for
a Mesa beam while other types of thermal noise decrease as well. We then
develop an iterative process that reconstructs the mirror to specifically
account for finite mirror effects. This allows us to increase the D parameter
and lower the coating noise by about 30% compared to the original Mesa
configuration.Comment: 13 pages, 12 figures, 4 tables. Referee input included and typos
fixed. Accepted by Phys. Rev.
Self-Renormalization of the Classical Quasilocal Energy
Pointlike objects cause many of the divergences that afflict physical
theories. For instance, the gravitational binding energy of a point particle in
Newtonian mechanics is infinite. In general relativity, the analog of a point
particle is a black hole and the notion of binding energy must be replaced by
quasilocal energy. The quasilocal energy (QLE) derived by York, and elaborated
by Brown and York, is finite outside the horizon but it was not considered how
to evaluate it inside the horizon. We present a prescription for finding the
QLE inside a horizon, and show that it is finite at the singularity for a
variety of types of black hole. The energy is typically concentrated just
inside the horizon, not at the central singularity.Comment: 7 pages, 4 figure
The Discrete Frenet Frame, Inflection Point Solitons And Curve Visualization with Applications to Folded Proteins
We develop a transfer matrix formalism to visualize the framing of discrete
piecewise linear curves in three dimensional space. Our approach is based on
the concept of an intrinsically discrete curve, which enables us to more
effectively describe curves that in the limit where the length of line segments
vanishes approach fractal structures in lieu of continuous curves. We verify
that in the case of differentiable curves the continuum limit of our discrete
equation does reproduce the generalized Frenet equation. As an application we
consider folded proteins, their Hausdorff dimension is known to be fractal. We
explain how to employ the orientation of carbons of amino acids along
a protein backbone to introduce a preferred framing along the backbone. By
analyzing the experimentally resolved fold geometries in the Protein Data Bank
we observe that this framing relates intimately to the discrete
Frenet framing. We also explain how inflection points can be located in the
loops, and clarify their distinctive r\^ole in determining the loop structure
of foldel proteins.Comment: 14 pages 12 figure
Fundamental bounds on transmission through periodically perforated metal screens with experimental validation
This paper presents a study of transmission through arrays of periodic
sub-wavelength apertures. Fundamental limitations for this phenomenon are
formulated as a sum rule, relating the transmission coefficient over a
bandwidth to the static polarizability. The sum rule is rigorously derived for
arbitrary periodic apertures in thin screens. By this sum rule we establish a
physical bound on the transmission bandwidth which is verified numerically for
a number of aperture array designs. We utilize the sum rule to design and
optimize sub-wavelength frequency selective surfaces with a bandwidth close to
the physically attainable. Finally, we verify the sum rule and simulations by
measurements of an array of horseshoe-shaped slots milled in aluminum foil.Comment: 10 pages, 11 figures. Updated Introduction and Conclusion
Analysis on Aging in the Generalized Random Energy Model
A new dynamics more natural than that proposed by Bouchaud and Dean is
introduced to the Generalized Random Energy Model, and the master equation for
the dynamics is solved exactly to calculate the time correlation function.
Although our results are very similar to those obtained by Bouchaud and Dean
qualitatively, the exponents for power law relaxation are different. The
Zero-Field-Cooled magnetization is also calculated with a relation between the
correlation function and the response function which holds even if the
relaxation is non-equilibrium. The validity of these analytic results are
confirmed by numerical simulations.Comment: 12 pages, 5 figures, submitted to J. Phys. Sci. Jp
Statistical and systematic errors for gravitational-wave inspiral signals: A principal component analysis
Identifying the source parameters from a gravitational-wave measurement alone
is limited by our ability to discriminate signals from different sources and
the accuracy of the waveform family employed in the search. Here we address
both issues in the framework of an adapted coordinate system that allows for
linear Fisher-matrix type calculations of waveform differences that are both
accurate and computationally very efficient. We investigate statistical errors
by using principal component analysis of the post-Newtonian (PN) expansion
coefficients, which is well conditioned despite the Fisher matrix becoming ill
conditioned for larger numbers of parameters. We identify which combinations of
physical parameters are most effectively measured by gravitational-wave
detectors for systems of neutron stars and black holes with aligned spin. We
confirm the expectation that the dominant parameter of the inspiral waveform is
the chirp mass. The next dominant parameter depends on a combination of the
spin and the symmetric mass ratio. In addition, we can study the systematic
effect of various spin contributions to the PN phasing within the same
parametrization, showing that the inclusion of spin-orbit corrections up to
next-to-leading order, but not necessarily of spin-spin contributions, is
crucial for an accurate inspiral waveform model. This understanding of the
waveform structure throughout the parameter space is important to set up an
efficient search strategy and correctly interpret future gravitational-wave
observations.Comment: 16 pages, 7 figures, pdfLaTeX, improved presentation, matches
published versio
Atlas of interpreted photography of southern Africa from TIROS satellites I to VIII
Surface features of southern Africa based on interpreted photographs taken by TIROS SATELLITE
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