Motile cilia are hair-like protrusions from epithelial cells that beat collectively to transport fluid. On the tissue level, cilia serve diverse biological functions, such as mucociliary clearance in the airways and cerebrospinal fluid transport in the brain ventricles. Yet, the relationship between the structure and organization of ciliated tissues and their biological function remains elusive.
An Inquiring Minds Public Lecture from the School of Physics
The world of quantum physics appears mysterious, even spooky, and far removed from everyday phenomena we can observe in the world around us. Especially the realm of living organisms was thought to be far too disorganized and noisy for quantum phenomena to play a role.
Excitation waves are propagating spatiotemporal structures observed in many biological, chemical, and physical systems. They can be described as a reaction-diffusion (RD) wave in which an autocatalytic reaction zone propagates via diffusion without mass transport. More common types of RD waves are the propagation of an action potential in a nerve, the spread of electrical depolarization waves on the heart surface, the (human spectator) stadium wave, or a forest fire.
Migratory birds and other animals possess a physiological magnetic compass that helps them to find directions, but the biophysical mechanism underlying this ability remains a mystery. One currently much discussed hypothesis is that light-induced magnetically sensitive radical pair reactions may provide the first step of a magnetic signal.
Two-dimensional crystals have received a lot of attention for their promise of a wide range of applications, and as a platform to study fundamentally new physics. Towards new applications, black phosphorus is a particularly exciting material because of its direct and tunable bandgap from 0.4-1.5 eV and high mobility carriers. However, samples degrade rapidly in air and are mysteriously p-doped.
In this talk, I describe 3 counterintuitive behaviors in simple physical systems. First, I describe experiments showing that small particles climb up a waterful to contaminate a clean reservoir upstream. Second, I describe climbing of shear thickening fluids up a vibrating rod. And third, I describe separation on fine grains from large boulders on asteroids.
All of these behaviors are surprising and counterintuitive, and all follow from mathematical and physical principles that have been known for decades, but have only recently been rediscovered.
An inclusion of non-colloidal particles in a Newtonian liquid can fundamentally change the interfacial dynamics and even cause interfacial instabilities. In this talk, we report a particle-induced fingering instability when a mixture of particles and viscous oil is injected radially into a Hele-Shaw cell.