Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: H 21cm emission as a tracer of gas during the evolution from
  protoplanetary to debris disks
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org