Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On gamma-ray bursts and their biological effects :a case for an
  extrinsic trigger of the Cambrian explosion ?   We discuss some the effects of local gamma-ray bursts on the earth's
atmosphere. A rough calculation of the fraction of ozone destruction by
catalytic $NO_{x}$ cycles is given, which in turn serves to argue how the large
flux of gammas from these events would have indirectly provoked major
extinction of living organisms. We give specific examples of these features,
and tentatively identify the Cambrian explosion seen in the actual fossil
record as an event caused by a GRB.

26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an