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R D Kamien

Publications and source records attributed to R D Kamien.

4 recordsLinked to original sources
PubMed2005

Dynamics of shallow impact cratering.

We present data for the time dependence of wooden spheres penetrating into a loose noncohesive packing of glass beads. The stopping time is a factor of 3 longer than the time d/v0 needed to travel the total penetration distance d at the impact speed v0. The acceleration decreases monotonically throughout the impact. These kinematics are modeled by a position- and velocity-dependent stopping force that is constrained to reproduce prior observations for the scaling of the penetration depth with the total drop distance.

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PubMed2001

Dislocation geometry in the TGB(A) phase: linear theory.

We demonstrate that an arbitrary system of screw dislocations in a smectic-A liquid crystal may be consistently treated within harmonic elasticity theory, provided that the angles between dislocations are sufficiently small. Using this theory, we calculate the ground-state configuration of the TGB(A) phase. We obtain an estimate of the twist-grain-boundary spacing and screw dislocation spacing in a boundary in terms of the macroscopic parameters, in reasonable agreement with experimental results.

Journal Article↗
PubMed1999

Polymer shape anisotropy and the depletion interaction.

We calculate the second and third virial coefficients of the effective sphere-sphere interaction due to polymer-induced depletion forces. By utilizing the anisotropy of a typical polymer conformation, we can consider polymers that are roughly the same size as the spheres. We argue that recent experiments are laboratory evidence for polymer shape anisotropy.

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