Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct measurement of the intermolecular forces confining a single
  molecule in an entangled polymer solution   We use optical tweezers to directly measure the intermolecular forces acting
on a single polymer imposed by surrounding entangled polymers (115 kbp DNA, 1
mg/ml). A tube-like confining field was measured in accord with the key
assumption of reptation models. A time-dependent harmonic potential opposed
transverse displacement, in accord with recent simulation findings. A tube
radius of 0.8 microns was determined, close to the predicted value (0.5
microns). Three relaxation modes (~0.4, 5 and 30 s) were measured following
transverse displacement, consistent with predicted relaxation mechanisms.

20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th