Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the parabolic-elliptic Patlak-Keller-Segel system in dimension 2 and
  higher   This review is dedicated to recent results on the 2d parabolic-elliptic
Patlak-Keller-Segel model, and on its variant in higher dimensions where the
diffusion is of critical porous medium type. Both of these models have a
critical mass $M_c$ such that the solutions exist globally in time if the mass
is less than $M_c$ and above which there are solutions which blowup in finite
time. The main tools, in particular the free energy, and the idea of the
methods are set out. A number of open questions are also stated.

34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess