Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sterols sense swelling in lipid bilayers   In the mimetic membrane system of phosphatidylcholine bilayers, thickening
(pre-critical behavior, anomalous swelling) of the bilayers is observed, in the
vicinity of the main transition, which is non-linear with temperature. The
sterols cholesterol and androsten are used as sensors in a time-resolved
simultaneous small- and wide angle x-ray diffraction study to investigate the
cause of the thickening. We observe precritical behavior in the pure lipid
system, as well as with sterol concentrations less than 15%. To describe the
precritical behavior we introduce a theory of precritical phenomena.The good
temperature resolution of the data shows that a theory of the influence of
fluctuations needs modification. The main cause of the critical behavior
appears to be a changing hydration of the bilayer.

18
The categories of this paper are: econ
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int