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Physics and Astronomy Colloquia
Speaker: Martina Gerken ( University of Kiel)
Periodic dielectric photonic nanostructures are
used extensively as transducers in refractive index sensors. Photonic crystal
slabs provide sharp resonances in the transmission and reflection spectrum.
Changes in resonance wavelength, resonance angle, or resonance intensity are
measured to monitor changes in the analyte region on top of the structure.
Nanostructured surfaces and the application of different modes for an
intensity-based readout are investigated. A reader device for label-free
cellular assays with the same footprint as a microtiter plate is presented and
employed for G protein-coupled receptor (GPCR) experiments. By specific
biofunctionalization of the nanostructured surface, specific molecule capture
is achieved. A handheld intensity-based measurement setup is demonstrated that
allows for imaging detection of binding events at the surface.
On: March 31, 2017 From: 10:00 am To: 11:00 am
Speaker: Dr Sarah Ballard ( University of Washington)
The Solar System furnishes the
most familiar planetary architecture:
many planets, orbiting nearly coplanar to one
another. However, the most common planetary systems
in the Milky Way orbit much smaller M dwarf stars, and these may present a very
different blueprint. The Kepler data set has uncovered more than 100 exoplanets
orbiting stars half the mass of the sun and smaller. Half of these planets reside in systems with at least one
additional planet. The data much prefer a model with two distinct modes of
planet formation around M dwarfs, which occur in roughly equal measure. One
mode is one very similar to the Solar System in terms of multiplicity and
coplanarity, and the other is very dissimilar. In the context of the “Kepler
Dichotomy,” we've studied the broadband transmission spectra (with data from
Kepler and hundreds of hours of Spitzer observations) of dozens of M
dwarf planets: half of which reside in one
type of planetarysystem, and half in the
other. Although the data set is too small and the observational uncertainty too
large to characterize any one system alone, I'll describe ensemble trends between planetary dynamics
and atmospheric content and how we're leveraging these studies to maximize the
return of forthcoming JWST studies of potentially habitable exoplanets.
On: April 7, 2017 From: 10:00 am To: 11:00 am
Speaker: Dr Katja Poppenhager ( TBC)
Exoplanets - planets around other stars - are practically everywhere: on
average, every cool star hosts at least one exoplanet. Even systems with
several planets, like our own system, seem to be quite common in our galaxy.
However, their architectures can be very different from the solar system:
exoplanets can be in very close orbits around their host stars with orbital
periods of only a few days. At such close distances, any magnetic phenomena of
the host star, which are collectively called "magnetic activity", may
have effects on their exoplanets and can even lead to atmosphere loss of the
planet. Measuring how magnetic activity of stars evolves over time is a crucial
component for understanding exoplanets, their atmospheres, and their potential
habitability. I will present new insights into the activity evolution of host
stars, what observational progress we can expect over the next years, and how
our understanding of exoplanet habitability is shaped by it.
On: April 14, 2017 From: 10:00 am To: 11:00 am
Speaker: Dr Silvia Vignolini ( University of Cambridge)
On: April 21, 2017 From: 10:00 am To: 11:00 am