2,524 research outputs found
Preferential interaction coefficient for nucleic acids and other cylindrical poly-ions
The thermodynamics of nucleic acid processes is heavily affected by the
electric double-layer of micro-ions around the polyions. We focus here on the
Coulombic contribution to the salt-polyelectrolyte preferential interaction
(Donnan) coefficient and we report extremely accurate analytical expressions
valid in the range of low salt concentration (when polyion radius is smaller
than the Debye length). The analysis is performed at Poisson-Boltzmann level,
in cylindrical geometry, with emphasis on highly charged poly-ions (beyond
``counter-ion condensation''). The results hold for any electrolyte of the form
:. We also obtain a remarkably accurate expression for the electric
potential in the vicinity of the poly-ion
Automatically Verifying Temporal Properties of Pointer Programs with Cyclic Proof
In this article, we investigate the automated verification of temporal properties of heap-aware programs. We propose a deductive reasoning approach based on cyclic proof. Judgements in our proof system assert that a program has a certain temporal property over memory state assertions, written in separation logic with user-defined inductive predicates, while the proof rules of the system unfold temporal modalities and predicate definitions as well as symbolically executing programs. Cyclic proofs in our system are, as usual, finite proof graphs subject to a natural, decidable soundness condition, encoding a form of proof by infinite descent. We present a proof system tailored to proving CTL properties of nondeterministic pointer programs, and then adapt this system to handle fair execution conditions. We show both versions of the system to be sound, and provide an implementation of each in the Cyclist theorem prover, yielding an automated tool that is capable of automatically discovering proofs of (fair) temporal properties of pointer programs. Experimental evaluation of our tool indicates that our approach is viable, and offers an interesting alternative to traditional model checking techniques
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