Compaction of Rods: Relaxation and Ordering in Vibrated, Anisotropic Granular Material

We report on experiments to measure the temporal and spatial evolution of packing arrangements of anisotropic, cylindrical granular material, using high-resolution capacitive monitoring. In these experiments, the particle configurations start from an initially disordered, low-packing-fraction state and under vertical vibrations evolve to a dense, highly ordered, nematic state in which the long particle axes align with the vertical tube walls. We find that the orientational ordering process is reflected in a characteristic, steep rise in the local packing fraction. At any given height inside the packing, the ordering is initiated at the container walls and proceeds inward. We explore the evolution of the local as well as the height-averaged packing fraction as a function of vibration parameters and compare our results to relaxation experiments conducted on spherically shaped granular materials.Comment: 9 pages incl. 7 figure

Role of Left Ventricular Twist Mechanics in the Assessment of Cardiac Dyssynchrony in Heart Failure

The authors discuss an incremental value of assessing left ventricular (LV) twist mechanics in patients with heart failure (HF) and its potential usefulness in characterizing response to cardiac resynchronization therapy (CRT) and reversal of LV remodeling at 6 months follow-up. They also underscore a critical relationship between LV lead position and changes in LV twist after CRT, and suggest that the reversal of LV remodeling in HF patients following CRT primarily results from restoration of the global sequence of LV twist mechanics