4,425 research outputs found
Effects of behavioral response and vaccination policy on epidemic spreading - an approach based on evolutionary-game dynamics
date of Acceptance: 23/06/2014 This work was supported by the National Natural Science Foundation of China (Grant Nos. 11331009, 11135001, 11105025). Y.-C.L. was supported by AFOSR under Grant No. FA9550-10-1-0083.Peer reviewedPublisher PD
Bidirectional outflows as evidence of magnetic reconnection leading to a solar microflare
Magnetic reconnection is a rapid energy release process that is believed to
be responsible for flares on the Sun and stars. Nevertheless, such
flare-related reconnection is mostly detected to occur in the corona, while
there have been few studies concerning the reconnection in the chromosphere or
photosphere. Here we present both spectroscopic and imaging observations of
magnetic reconnection in the chromosphere leading to a microflare. During the
flare peak time, chromospheric line profiles show significant
blueshifted/redshifted components on the two sides of the flaring site,
corresponding to upflows and downflows with velocities of (70--80) km
s, comparable with the local Alfv\'{e}n speed as expected by the
reconnection in the chromosphere. The three-dimensional nonlinear force-free
field configuration further discloses twisted field lines (a flux rope) at a
low altitude, cospatial with the dark threads in He I 10830 \r{A} images. The
instability of the flux rope may initiate the flare-related reconnection. These
observations provide clear evidence of magnetic reconnection in the
chromosphere and show the similar mechanisms of a microflare to those of major
flares.Comment: 16 pages, 5 figures, accepted for publication in ApJ
Type-I superconductivity in AlRe
While the pure elements tend to exhibit Type-I rather than Type-II
superconductivity, nearly all compound superconductors are Type-II, with only a
few known exceptions. We report single crystal growth and physical
characterization of the rhenium aluminide AlRe, which we conclude is a
Type-I superconductor based on magnetization, ac-susceptibility, and
specific-heat measurements. This detection of superconductivity, despite the
strong similarity of AlRe to a family of W and Mo aluminides that do not
superconduct, suggests that these aluminides are an ideal testbed for
identifying the relative importance of valence electron count and inversion
symmetry in determining whether a material will superconduct.Comment: 9 pages, 7 figures, CIF file as ancillar
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