4,952 research outputs found
On the origin of the unusual behavior in the stretching of single-stranded DNA
Force extension curves (FECs), which quantify the response of a variety of
biomolecules subject to mechanical force (), are often quantitatively fit
using worm-like chain (WLC) or freely-jointed chain (FJC) models. These models
predict that the chain extension, , normalized by the contour length
increases linearly at small and at high forces scale as where = 0.5 for WLC and unity for FJC. In contrast,
experiments on ssDNA show that over a range of and ionic concentration,
scales as , which cannot be explained using WLC or FJC models.
Using theory and simulations we show that this unusual behavior in FEC in ssDNA
is due to sequence-independent polyelectrolyte effects. We show that the arises because in the absence of force the tangent correlation function,
quantifying chain persistence, decays algebraically on length scales on the
order of the Debye length. Our theory, which is most appropriate for monovalent
salts, quantitatively fits the experimental data and further predicts that such
a regime is not discernible in double stranded DNA.Comment: Accepted for publication in JC
Towards Assume-Guarantee Profiles for Autonomous Vehicles
Rules or specifications for autonomous vehicles are currently formulated on a case-by-case basis, and put together in a rather ad-hoc fashion. As a step towards eliminating this practice, we propose a systematic procedure for generating a set of supervisory specifications for self-driving cars that are 1) associated with a distributed assume-guarantee structure and 2) characterizable by the notion of consistency and completeness. Besides helping autonomous vehicles make better decisions on the road, the assume-guarantee contract structure also helps address the notion of blame when undesirable events occur. We give several game-theoretic examples to demonstrate applicability of our framework
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