372,793 research outputs found
New Primordial-Magnetic-Field Limit from The Latest LIGO S5 data
Since the energy momentum tensor of a magnetic field always contains a spin-2
component in its anisotropic stress, stochastic primordial magnetic field (PMF)
in the early universe must generate stochastic gravitational wave (GW)
background. This process will greatly affect the relic gravitational wave
(RGW), which is one of major scientific goals of the laser interferometer GW
detections. Recently, the fifth science (S5) run of laser interferometer
gravitational-wave observatory (LIGO) gave a latest upper limit
on the RGW background. Utilizing this upper
limit, we derive new PMF Limits: for a scale of galactic cluster
Mpc, the amplitude of PMF, that produced by the electroweak phase transition
(EPT), has to be weaker than Gauss; for a
scale of supercluster Mpc, the amplitude of PMF has to be weaker
than Gauss. In this manner, GW observation
has potential to make interesting contributions to the study of primordial
magnetic field.Comment: 17 pages, 3 figures, accepted for publication in PR
Architectural implications for context adaptive smart spaces
Buildings and spaces are complex entities containing complex social structures and interactions. A smart space is a composite of the users that inhabit it, the IT infrastructure that supports it, and the sensors and appliances that service it. Rather than separating the IT from the buildings and from the appliances that inhabit them and treating them as separate systems, pervasive computing combines them and allows them to interact. We outline a reactive context architecture that supports this vision of integrated smart spaces and explore some implications for building large-scale pervasive systems
Periodic ripples in suspended graphene
We study the mechanism of wrinkling of suspended graphene, by means of
atomistic simulations. We argue that the structural instability under edge
compression is the essential physical reason for the formation of periodic
ripples in graphene. The ripple wavelength and out-of-plane amplitude are found
to obey 1/4-power scaling laws with respect to edge compression. Our results
also show that parallel displacement of the clamped boundaries can induce
periodic ripples, with oscillation amplitude roughly proportional to the 1/4
power of edge displacement. The results are fundamental to graphene's
applications in electronics.Comment: 5 Figure
Optical spectroscopy study of Nd(O,F)BiS2 single crystals
We present an optical spectroscopy study on F-substituted NdOBiS
superconducting single crystals grown using KCl/LiCl flux method. The
measurement reveals a simple metallic response with a relatively low screened
plasma edge near 5000 \cm. The plasma frequency is estimated to be 2.1 eV,
which is much smaller than the value expected from the first-principles
calculations for an electron doping level of x=0.5, but very close to the value
based on a doping level of 7 of itinerant electrons per Bi site as
determined by ARPES experiment. The energy scales of the interband transitions
are also well reproduced by the first-principles calculations. The results
suggest an absence of correlation effect in the compound, which essentially
rules out the exotic pairing mechanism for superconductivity or scenario based
on the strong electronic correlation effect. The study also reveals that the
system is far from a CDW instability as being widely discussed for a doping
level of x=0.5.Comment: 5 pages, 5 figure
Room-Temperature Ferrimagnet with Frustrated Antiferroelectricity: Promising Candidate Toward Multiple State Memory
On the basis of first-principles calculations we show that the M-type
hexaferrite BaFe12O19 exhibits frustrated antiferroelectricity associated with
its trigonal bipyramidal Fe3+ sites. The ferroelectric (FE) state of BaFe12O19,
reachable by applying an external electric field to the antiferroelectric (AFE)
state, can be made stable at room temperature by appropriate element
substitution or strain engineering. Thus M-type hexaferrite, as a new type of
multiferoic with coexistence of antiferroelectricity and ferrimagnetism,
provide a basis for studying the phenomenon of frustrated antiferroelectricity
and realizing multiple state memory devices.Comment: supporting material available via email. arXiv admin note: text
overlap with arXiv:1210.7116 by other author
Immune Modulation as a Treatment for Abdominal Aortic Aneurysms
In the United States, over 200,000 new patients are diagnosed with abdominal aortic aneurysm (AAA) each year. Consequently, over 40,000 highly morbid aortic reconstructions are performed each year to prevent aneurysm rupture, a catastrophic event associated with near-certain mortality. No pharmaceutical currently exists to slow aneurysm growth, but a 50% reduction in diameter growth per annum could halve the number of aortic reconstructions required. Therefore, successful use of cell therapy to modulate chronic inflammation hallmark to AAA to slow diameter expansion represents a potentially paradigm-altering treatment
- âŠ