Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Remarks on some typical assumptions in dynamo theory   Some concepts used in the theory of convection-driven dynamos in rotating
spherical fluid shells are discussed. The analogy between imposed magnetic
fields and those generated by dynamo action is evaluated and the role of the
Elsasser number is considered. Eddy diffusivities are essential ingredients in
numerical dynamo simulations, but their effects could be misleading. New
aspects of the simultaneous existence of different dynamo states are described.

23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat