33,491 research outputs found
Nonminimally coupled topological-defect boson stars: Static solutions
We consider spherically symmetric static composite structures consisting of a
boson star and a global monopole, minimally or non-minimally coupled to the
general relativistic gravitational field. In the non-minimally coupled case,
Marunovic and Murkovic have shown that these objects, so-called boson D-stars,
can be sufficiently gravitationally compact so as to potentially mimic black
holes. Here, we present the results of an extensive numerical parameter space
survey which reveals additional new and unexpected phenomenology in the model.
In particular, focusing on families of boson D-stars which are parameterized by
the central amplitude of the boson field, we find configurations for both the
minimally and non-minimally coupled cases that contain one or more shells of
bosonic matter located far from the origin. In parameter space, each shell
spontaneously appears as one tunes through some critical central amplitude of
the boson field. In some cases the shells apparently materialize at spatial
infinity: in these instances their areal radii are observed to obey a universal
scaling law in the vicinity of the critical amplitude. We derive this law from
the equations of motion and the asymptotic behavior of the fields.Comment: 17 pages, 24 figure
Automated microorganism Sample Collection Module
Modified Gelman Sampler obtains representative sample of microorganism population. Proposed Sample Collection Module is based on direct inoculation of selected solid growth media encased in a cartridge at all times except during inoculation. Cartridge can be handled with no danger of contamination to sample or operator
The Abundance of Kaluza-Klein Dark Matter with Coannihilation
In Universal Extra Dimension models, the lightest Kaluza-Klein (KK) particle
is generically the first KK excitation of the photon and can be stable, serving
as particle dark matter. We calculate the thermal relic abundance of the KK
photon for a general mass spectrum of KK excitations including full
coannihilation effects with all (level one) KK excitations. We find that
including coannihilation can significantly change the relic abundance when the
coannihilating particles are within about 20% of the mass of the KK photon.
Matching the relic abundance with cosmological data, we find the mass range of
the KK photon is much wider than previously found, up to about 2 TeV if the
masses of the strongly interacting level one KK particles are within five
percent of the mass of the KK photon. We also find cases where several
coannihilation channels compete (constructively and destructively) with one
another. The lower bound on the KK photon mass, about 540 GeV when just
right-handed KK leptons coannihilate with the KK photon, relaxes upward by
several hundred GeV when coannihilation with electroweak KK gauge bosons of the
same mass is included.Comment: 38 pages, 4 figure
Manual control theory applied to air traffic controller-pilot cooperation
Reduced runway separation standards are among the means which have been proposed for increasing airport capacity. The probability of a blunder will dominate the calculation of safe separation standards. Then the determinant of safe system performance will be the system reaction time comprised of the air traffic controller's detection, decision and communication delays, and the response times of the pilot and aircraft in executing a collision avoidance manuever. Estimates of these times, based on existing data, show that the delays ascribable to the human portions of the man-machine system are comparatively unimportant. New developments in radar, computers, and data links will be required to provide any substantial improvement of the existing system, and the goal of 2500 ft of separation may not be achievable
Achieving Consistent Doppler Measurements from SDO/HMI Vector Field Inversions
NASA's Solar Dynamics Observatory is delivering vector field observations of
the full solar disk with unprecedented temporal and spatial resolution;
however, the satellite is in a highly inclined geostationary orbit. The
relative spacecraft-Sun velocity varies by ~km/s over a day which
introduces major orbital artifacts in the Helioseismic Magnetic Imager data. We
demonstrate that the orbital artifacts contaminate all spatial and temporal
scales in the data. We describe a newly-developed three stage procedure for
mitigating these artifacts in the Doppler data derived from the Milne-Eddington
inversions in the HMI Pipeline. This procedure was applied to full disk images
of AR11084 to produce consistent Dopplergrams. The data adjustments reduce the
power in the orbital artifacts by 31dB. Furthermore, we analyze in detail the
corrected images and show that our procedure greatly improve the temporal and
spectral properties of the data without adding any new artifacts. We conclude
that this new and easily implemented procedure makes a dramatic improvement in
the consistency of the HMI data and in its usefulness for precision scientific
studies.Comment: 58 pages, 19 figures, submitted to Ap
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