Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A Hybrid model for the origin of photoluminescence from Ge nanocrystals
  in SiO$_2$ matrix
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin