7 research outputs found
Verticalization of bacterial biofilms
Biofilms are communities of bacteria adhered to surfaces. Recently, biofilms
of rod-shaped bacteria were observed at single-cell resolution and shown to
develop from a disordered, two-dimensional layer of founder cells into a
three-dimensional structure with a vertically-aligned core. Here, we elucidate
the physical mechanism underpinning this transition using a combination of
agent-based and continuum modeling. We find that verticalization proceeds
through a series of localized mechanical instabilities on the cellular scale.
For short cells, these instabilities are primarily triggered by cell division,
whereas long cells are more likely to be peeled off the surface by nearby
vertical cells, creating an "inverse domino effect". The interplay between cell
growth and cell verticalization gives rise to an exotic mechanical state in
which the effective surface pressure becomes constant throughout the growing
core of the biofilm surface layer. This dynamical isobaricity determines the
expansion speed of a biofilm cluster and thereby governs how cells access the
third dimension. In particular, theory predicts that a longer average cell
length yields more rapidly expanding, flatter biofilms. We experimentally show
that such changes in biofilm development occur by exploiting chemicals that
modulate cell length.Comment: Main text 10 pages, 4 figures; Supplementary Information 35 pages, 15
figure
The 2010 Interim Report of the Long-Baseline Neutrino Experiment Collaboration Physics Working Groups
Corresponding author R.J.Wilson ([email protected]); 113 pages, 90 figuresCorresponding author R.J.Wilson ([email protected]); 113 pages, 90 figuresIn early 2010, the Long-Baseline Neutrino Experiment (LBNE) science collaboration initiated a study to investigate the physics potential of the experiment with a broad set of different beam, near- and far-detector configurations. Nine initial topics were identified as scientific areas that motivate construction of a long-baseline neutrino experiment with a very large far detector. We summarize the scientific justification for each topic and the estimated performance for a set of far detector reference configurations. We report also on a study of optimized beam parameters and the physics capability of proposed Near Detector configurations. This document was presented to the collaboration in fall 2010 and updated with minor modifications in early 2011
The 2010 Interim Report of the Long-Baseline Neutrino Experiment Collaboration Physics Working Groups
In early 2010, the Long-Baseline Neutrino Experiment (LBNE) science
collaboration initiated a study to investigate the physics potential of the
experiment with a broad set of different beam, near- and far-detector
configurations. Nine initial topics were identified as scientific areas that
motivate construction of a long-baseline neutrino experiment with a very large
far detector. We summarize the scientific justification for each topic and the
estimated performance for a set of far detector reference configurations. We
report also on a study of optimized beam parameters and the physics capability
of proposed Near Detector configurations. This document was presented to the
collaboration in fall 2010 and updated with minor modifications in early 2011.Comment: Corresponding author R.J.Wilson ([email protected]); 113
pages, 90 figure