349 research outputs found
Statistical analysis of variability properties of the Kepler blazar W2R 1926+42
We analyzed Kepler light curves of the blazar W2R 1926+42 that provided
nearly continuous coverage from quarter 11 through quarter 17 (589 days between
2011 and 2013) and examined some of their flux variability properties. We
investigate the possibility that the light curve is dominated by a large number
of individual flares and adopt exponential rise and decay models to investigate
the symmetry properties of flares. We found that those variations of W2R
1926+42 are predominantly asymmetric with weak tendencies toward positive
asymmetry (rapid rise and slow decay). The durations (D) and the amplitudes
(F0) of flares can be fit with log-normal distributions. The energy (E) of each
flare is also estimated for the first time. There are positive correlations
between logD and logE with a slope of 1.36, and between logF0 and logE with a
slope of 1.12. Lomb-Scargle periodograms are used to estimate the power
spectral density (PSD) shape. It is well described by a power law with an index
ranging between -1.1 and -1.5. The sizes of the emission regions, R, are
estimated to be in the range of 1.1*10^15 cm - 6.6*10^16 cm. The flare
asymmetry is difficult to explain by a light travel time effect but may be
caused by differences between the timescales for acceleration and dissipation
of high-energy particles in the relativistic jet. A jet-in-jet model also could
produce the observed log-normal distributions
A bilinear proof of decoupling for the cubic moment curve
Using a bilinear method that is inspired by the method of efficient
congruencing of Wooley [Woo16], we prove a sharp decoupling inequality for the
moment curve in .Comment: 28 pages; revised version incorporating referee comment
Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface Enhanced Raman Spectroscopy
Surface enhanced Raman spectroscopy (SERS) is a useful multidisciplinary
analytic technique. However, it is still a challenge to produce SERS substrates
that are highly sensitive, reproducible, stable, reusable, and scalable. Here,
we demonstrate that atomically thin boron nitride (BN) nanosheets have many
unique and desirable properties to help solve this challenge. The synergic
effect of the atomic thickness, high flexibility, stronger surface adsorption
capability, electrical insulation, impermeability, high thermal and chemical
stability of BN nanosheets can increase the Raman sensitivity by up to two
orders, and in the meantime attain long-term stability and extraordinary
reusability not achievable by other materials. These advances will greatly
facilitate the wider use of SERS in many fields
A short proof of decoupling for the moment curve
We give a short and elementary proof of the decoupling inequality
for the moment curve in , using a bilinear approach inspired by
the nested efficient congruencing argument of Wooley (arXiv:1708.01220).Comment: v2: 10 pages, minor correction
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