8,805 research outputs found
Magnetic reconnection at the earliest stage of solar flux emergence
On 2016 September 20, the Interface Region Imaging Spectrograph observed an
active region during its earliest emerging phase for almost 7 hours. The
Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory
observed continuous emergence of small-scale magnetic bipoles with a rate of
10 Mx~s. The emergence of magnetic fluxes and interactions
between different polarities lead to frequent occurrence of ultraviolet (UV)
bursts, which exhibit as intense transient brightenings in the 1400 \AA{}
images. In the meantime, discrete small patches with the same magnetic polarity
tend to move together and merge, leading to enhancement of the magnetic fields
and thus formation of pores (small sunspots) at some locations. The spectra of
these UV bursts are characterized by the superposition of several chromospheric
absorption lines on the greatly broadened profiles of some emission lines
formed at typical transition region temperatures, suggesting heating of the
local materials to a few tens of thousands of kelvin in the lower atmosphere by
magnetic reconnection. Some bursts reveal blue and red shifts of
100~km~s at neighboring pixels, indicating the spatially resolved
bidirectional reconnection outflows. Many such bursts appear to be associated
with the cancellation of magnetic fluxes with a rate of the order of
10 Mx~s. We also investigate the three-dimensional magnetic
field topology through a magneto-hydrostatic model and find that a small
fraction of the bursts are associated with bald patches (magnetic dips).
Finally, we find that almost all bursts are located in regions of large
squashing factor at the height of 1 Mm, reinforcing our conclusion that
these bursts are produced through reconnection in the lower atmosphere.Comment: ApJ, 10 figure
An Analysis of Dynamic Game Strategy of Privacy Protection in Personalization
E-business enterprises provide personalize services for customers based on their privacy information. However, customers benefit from personalization while suffering from privacy concern. The tradeoff between consumers’ benefit function and firms’ earnings function are explored when an incumbent adopts privacy protection in perfect monopoly market. It also found that when the potential entrant entered into the market, the incumbent that adopted privacy protection can maintain more market shares than one not adopted. At last, we extended this paper and further found that if potential entrant entered into the market with privacy protection would lose more profit because of the large cost of privacy protection. This means the privacy protection that the incumbent adopted has played a certain barriers to entrant
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