Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Use of a magnetic fluid for particle size analysis by a sedimentation
  method   A new method of particle size analysis of micrometer-sized particles is
discussed. The improved method of sedimentation analysis with magnetic fluids
has the potential and versatility to characterize polydisperse systems.

2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom