@article{ISI:000342838700001,
 abstract = {The self-organized motion of vast numbers of creatures in a single
direction is a spectacular example of emergent order. Here, we recreate
this phenomenon using actuated nonliving components. We report here that
millimetre-sized tapered rods, rendered motile by contact with an
underlying vibrated surface and interacting through a medium of
spherical beads, undergo a phase transition to a state of spontaneous
alignment of velocities and orientations above a threshold bead area
fraction. Guided by a detailed simulation model, we construct an
analytical theory of this flocking transition, with two ingredients: a
moving rod drags beads; neighbouring rods reorient in the resulting flow
like a weathercock in the wind. Theory and experiment agree on the
structure of our phase diagram in the plane of rod and bead
concentrations and power-law spatial correlations near the phase
boundary. Our discovery suggests possible new mechanisms for the
collective transport of particulate or cellular matter.},
 article-number = {4688},
 author = {Kumar, Nitin and Soni, Harsh and Ramaswamy, Sriram and Sood, A. K.},
 doi = {10.1038/ncomms5688},
 issn = {2041-1723},
 journal = {NATURE COMMUNICATIONS},
 month = {SEP},
 orcid-numbers = {Kumar, Nitin/0000-0003-2697-4842},
 researcherid-numbers = {Kumar, Nitin/AAS-3576-2020},
 times-cited = {97},
 title = {Flocking at a distance in active granular matter},
 unique-id = {ISI:000342838700001},
 volume = {5},
 year = {2014}
}