19,481 research outputs found
Testing quantum gravity effects with latest CMB observations
Inspired by quantum gravitational physics, the approach of non-commutative
(NC) phase space leads to a modified dispersion relation of gravitational
waves. This feature, if applied to the very early universe, gives rise to a
modified power spectrum of primordial tensor perturbations with a suppression
of power on large scales. We confront this phenomenon with the BICEP2 and
Planck experiments, and show that inflation with the modified dispersion
relation can simultaneously fit the observations better than the standard
inflationary paradigm. In particular, the numerical result implies that with
the latest cosmological microwave background (CMB) observations, a quantum
gravity modified power spectrum of primordial tensor modes is preferred at a
statistical significance of more than compared with the minimal
model. Our study indicates that the potential tension between the BICEP2 and
Planck data may be resolved by quantum gravity effects.Comment: 5 pages, 2 figures, comments are welcom
Large Nonlocal Non-Gaussianity from a Curvaton Brane
We use a generalized delta N formalism to study the generation of the
primordial curvature perturbation in the curvaton brane scenario inspired by
stringy compactifications. We note that the non-Gaussian features, especially
the trispectra, crucially depend on the decay mechanism in a general curvaton
scenario. Specifically, we study the bispectra and trispectra of the curvaton
brane model in detail to illustrate the importance of curvaton decay in
generating nonlinear fluctuations. When the curvaton brane moves
nonrelativistically during inflation, the shape of non-Gaussianity is local,
but the corresponding size is different from that in the standard curvaton
scenario. When the curvaton brane moves relativistically in inflationary stage,
the shape of non-Gaussianity is of equilateral type.Comment: 24 pages, 2 figure
ADAPTIVE FEC WITH DYNAMICALLY BLOCK SIZE CONTROL FOR VIDEO STREAMING OVER WIRELESS NETWORK
[[conferencetype]]國際[[conferencedate]]20150722~20150724[[iscallforpapers]]Y[[conferencelocation]]Osaka,Japa
Synthesis and characterization of molecularly imprinted polymers and their application in preconcentrators for gas phase sensors
Various of molecularly imprinted polymers were synthesized by different protocols. Piezoelectric quartz crystals coated with molecularly imprinted polymers were prepared to detect small organic vapors. Hydroquinone (HQ) and Phenol (P) have been used as non-covalent bound templates in order to generate shape-selectivity cavities in the polymer matrix. The recognition film was immobilized on the crystal surface via a pre-coated Poly(isobutylene) layer. The selective behaviors of the imprinted polymer films were studied by their steady-state response to various kinds of small organic vapors. The partition coefficients of polymers toward vapors were evaluated. The imprinted polymers exhibit high sensitivity and selectivity toward organic vapors as toluene and benzene, which are structurally related to the templates. Imprinted polymers prepared by different synthesis schemes were compared. The influence of template concentration and the polymer components was also investigated. The adsorption capacity of molecularly imprinted polymers was characterized and compared by breakthrough studies. From our results, molecularly imprinted polymer is promising for the development of selective piezoelectric sensor for organic vapor detection.;Different types of preconcentrator devices capable of pre-concentrating organic vapors at low ppm levels were fabricated and described. The target organic vapors were enriched onto a small bed of adsorbents and subsequently released by thermal desorption scheme. Solid adsorbents (Tenax GR, TA and molecularly imprinted polymers) were evaluated for possible use in a preconcentrator. Approximate preconcentration factor in the range of several thousand can be achieved by using the block polymer imprinted with hydroquinone
Doppler effect of gamma-ray bursts in the fireball framework
The influence of the Doppler effect in the fireball framework on the spectrum
of gamma-ray bursts is investigated. The study shows that the shape of the
expected spectrum of an expanding fireball remains almost the same as that of
the corresponding rest frame spectrum for constant radiations of the
bremsstrahlung, Comptonized, and synchrotron mechanisms as well as for that of
the GRB model. The peak flux spectrum and the peak frequency are obviously
correlated. When the value of the Lorentz factor becomes 10 times larger, the
flux of fireballs would be several orders of magnitude larger. The expansion
speed of fireballs is a fundamental factor of the enhancement of the flux of
gamma-ray bursts.Comment: 19 pages, 13 figure
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