From Pole-to-Pole Flights to Megacity Observatories

posted on September 27, 2012 by

Eric Kort (’04),   JPL –  NASA

Thursday, September 27, 2012 at 4:30 pm in Millikan Laboratory – Room 134 (Refreshments at 4:15 pm)

Abstract: Human activities have significantly perturbed our planet’s atmospheric  composition, with major consequences for our present and future Climate.  In particular, higher levels of long-lived greenhouse gases such as CO2, CH4, and N2O are playing a driving role in the climate change occurring today.  To better understand both the present climate and possible future climate scenarios, it is critical to observe atmospheric concentrations and distributions of these gases and improve our knowledge of current human and natural emissions levels.  In this talk, I will first discuss observation made from an aircraft travelling from pole-to-pole and focus on some surprises we found in the Arctic.  Moving from the global to urban scale, I’ll then focus on carbon emissions from cities, which presently represent the single largest human contribution to climate change.  Despite the large contribution of urban areas to the total greenhouse gas emission rate, there presently exists no method for robustly quantifying emissions changes, be they growth or reduction.  I’ll discuss the Megacity Carbon pilot project, which aims to develop and demonstrate an observing system that will be able to monitor megacity carbon emissions.  This entails both earth- & space-based observations, including the expansion of an observing network in the Los Angeles basin, with a potential site situated at Pomona College.

Colloquium: Small Stars with Small Planets and Big Consequences (HMC)

posted on September 25, 2012 by

Philip Muirhead, Caltech

Tuesday, September 25, 2012 at 4:30 pm, Galileo-Pryne at Harvey Mudd College (Refreshments at 4:15 pm)

Abstract: With the success of NASA’s Kepler Spacecraft, extrasolar planet science has entered a new era. Prior to Kepler’s launch exoplanet science was primarily concerned with gas-giant exoplanets, since gas giants comprised the majority of discoveries, numbering in the hundreds. NASA’s Kepler Mission has since discovered thousands of exoplanets with many of them terrestrial-sized. Of particular interest are terrestrial exoplanets orbiting low-mass stars, which are roughly 1/10 to 1/2 the mass of Sun. Low-mass stars dominate stellar populations, so understanding the prevalence of terrestrial exoplanets orbiting low-mass stars, life-harboring or otherwise, is crucial to understanding their prevalence in the Universe. I will present a ground-based observation program to characterize low-mass stars with exoplanets discovered by the Kepler Spacecraft, and our identification of the three smallest exoplanets detected to date: Kepler 41 b, c and d (formerly KOI 961 b, c and d). The program uses a fully-cryogenic infrared spectrograph built by myself and others and deployed on the 200-inch Hale Telescope at Palomar Observatory in Southern California.

Colloquium: Unwinding the Mechanics of Cucumber Tendrils

posted on September 24, 2012 by

Sharon Gerbode, Harvey Mudd College

Tuesday, September 18th at 4:30 pm, Millikan Room 134 (Refreshments at 4:15 pm)

Abstract:

Plant tendrils are specialized climbing organs that have fascinated biologists and physicists alike for centuries.  Initially straight tendrils attach at the tip to an elevated rigid support and then winch the plant upward by coiling into a helical morphology characterized by two helices of opposite handedness connected by a so-called “helical perversion.”  Charles Darwin surmised that coil tendrils serve as soft, springy attachments for the climbing plant.  Yet, the mechanical effect of the perverted helical shape of a coiled plant tendril has not been fully revealed.  Using a combination of experiments on Cucurbitaceae tendrils, physical models constructed from stretched rubber sheets, and numerical models of helical pervasions, we have uncovered that tendril coiling occurs via anisotropic shrinkage of a strip of specialized cells in the interior of the tendril.  Furthermore, variations in the mechanical behavior of tendrils as they become drier and “woodier” adds a new twist to the story of tendril coiling.

Colloquium: Student Summer Research

posted on September 11, 2012 by

This Thursday, September 11, 2012, five of our physics and astronomy students are presenting about their summer research. The event will begin with refreshments at 4:15 pm and continue with brief presentations by five students from 4:30-5:30 pm. Daniel Contreras ’13, Samuel Whitehead ’13, Carolyn Cross ’13, Rylan Grady ’13, and Claire Dickey ’12 will be presenting on the research they did this summer through SURP and other summer research programs.