Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Continuous upflows and sporadic downflows observed in active regions   We present a study of the temporal evolution of coronal loops in active
regions and its implications for the dynamics in coronal loops. We analyzed
images of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics
Observatory (SDO) at multiple temperatures to detect apparent motions in the
coronal loops. Quasi-periodic brightness fluctuations propagate upwards from
the loop footpoint in hot emission at 1MK, while sporadic downflows are seen in
cool emission below 1MK. The upward motion in hot emission increases just after
the cool downflows. The apparent propagating pattern suggests a hot upflow from
the loop footpoints, and is considered to supply hot plasma into the coronal
loop, but a wavelike phenomenon cannot be ruled out. Coronal condensation
occasionally happens in the coronal loop, and the cool material flows down to
the footpoint. Emission from cool plasma could have a significant contribution
to hot AIA channels in the event of coronal condensation.

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The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph