Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dependence of DNA persistence length on ionic strength of solutions with
  monovalent and divalent salts: a joint theory-experiment study   Using high-throughput Tethered Particle Motion single molecule experiments,
the double-stranded DNA persistence length, $L_p$, is measured in solutions
with Na$^+$ and Mg$^{2+}$ ions of various ionic strengths, $I$. Several
theoretical equations for $L_p(I)$ are fitted to the experimental data, but no
decisive theory is found which fits all the $L_p$ values for the two ion
valencies. Properly extracted from the particle trajectory using simulations,
$L_p$ varies from 30~nm to 55~nm, and is compared to previous experimental
results. For the Na$^+$ only case, $L_p$ is an increasing concave function of
$I^{-1}$, well fitted by Manning's electrostatic stretching approach, but not
by classical Odjik-Skolnick-Fixman theories with or without counter-ion
condensation. With added Mg$^{2+}$ ions, $L_p$ shows a marked decrease at low
$I$, interpreted as an ion-ion correlation effect, with an almost linear law in
$I^{-1}$, fitted by a proposed variational approach.

9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph