25,114 research outputs found
Electrostatic contribution to DNA condensation - application of 'energy minimization' in a simple model in strong Coulomb coupling regime
Bending of DNA from a straight rod to a circular form in presence of any of
the mono-, di-, tri- or tetravalent counterions has been simulated in strong
Coulomb coupling environment employing a previously developed energy
minimization simulation technique. The inherent characteristics of the
simulation technique allow monitoring the required electrostatic contribution
to the bending. The curvature of the bending has been found to play crucial
roles in facilitating electrostatic attractive potential energy. The total
electrostatic potential energy has been found to decrease with bending which
indicates that bending a straight DNA to a circular form or to a toroidal form
in presence of neutralizing counterions is energetically favorable and
practically is a spontaneous phenomenon
Hyperscaling violation, quasinormal modes and shear diffusion
We study quasinormal modes of shear gravitational perturbations for
hyperscaling violating Lifshitz theories, with Lifshitz and hyperscaling
violating exponents and . The lowest quasinormal mode frequency
yields a shear diffusion constant which is in agreement with that obtained in
previous work by other methods. In particular for theories with where is the boundary spatial dimension, the shear
diffusion constant exhibits power-law scaling with temperature, while for
, it exhibits logarithmic scaling. We then calculate certain
2-point functions of the dual energy-momentum tensor holographically for , identifying the diffusive poles with the quasinormal modes
above. This reveals universal behaviour for the
viscosity-to-entropy-density ratio for all .Comment: v2: Latex, 21pgs, more details of analysis, review of shear diffusion
from membrane paradigm, references added, matches version to be publishe
- …