Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The shape and erosion of pebbles   The shapes of flat pebbles may be characterized in terms of the statistical
distribution of curvatures measured along their contours. We illustrate this
new method for clay pebbles eroded in a controlled laboratory apparatus, and
also for naturally-occurring rip-up clasts formed and eroded in the Mont
St.-Michel bay. We find that the curvature distribution allows finer
discrimination than traditional measures of aspect ratios. Furthermore, it
connects to the microscopic action of erosion processes that are typically
faster at protruding regions of high curvature. We discuss in detail how the
curvature may be reliable deduced from digital photographs.

20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org