Daniel Borrero-Echeverry, Assistant Professor of Physics
When a small droplet of oil is dropped into a container filled with oil, it splashes before coalescing with the fluid bath. However, in order to do so the droplet must clear the air layer separating it and fluid bath. It was recently discovered that if the fluid bath is vibrated vertically, the air layer can transfer sufficient momentum to the droplet, so that instead of coalescing it bounces upward and can remain suspended indefinitely. As it bounces, the droplet creates small ripples on the surface of the bath, which affects how the droplet will bounce. This interaction between droplets and their own wave fields leads to dynamics that have previously been thought to be restricted to quantum mechanics such as quantized bound states. This summer we will build an apparatus for studying bouncing drops and focus on two projects:
1.) Implementing synthetic schlieren imaging for quantifying deformation of the fluid interface: In this technique a pattern of dots is placed at the bottom of the fluid bath. As the fluid surface is deformed by the bouncing drop, the dot pattern appears to shift as light is refracted across the curved surfaces in the wave field. By analyzing the shifts in the dot pattern, the deformation of the fluid surface can be quantified.
2.) Implementing optical actuation of bouncing drops: Any perturbation to the fluid interface will also affect the dynamics of the bouncing droplets. We will implement a laser system to generate controlled disturbances to fluid surface, which will enable us to tune the behavior of the bouncing drops in a controlled manner.
Melinda Butterworth, Assistant Professor of Environmental & Earth Sciences
My research focuses on the emergence of environmentally mediated infectious diseases. One important factor governing spatial and temporal disease activity is climate, specifically temperature and precipitation. The disease of study for this SCRP project is dengue fever and the associated mosquito vector (Aedes aegypti). Dengue fever has reappeared in the southern United States every year since 2009, after an absence of nearly 70 years. While there are many reasons contributing to this, there is growing scientific evidence that climate change may be partially facilitating this re-emergence. This is because warmer temperatures allow for longer mosquito seasons and decrease the extrinsic incubation period of the dengue fever virus inside the mosquito. This summer we will study how climate variability impacts the potential for dengue transmission in key sites in Florida and Texas. To do this, we will use a mosquito simulation model driven by observed meteorological data and future climate change projections. Our goal is to understand: (1) how frequently the climate in these locations can support local transmission, (2) the average season length of dengue transmission potential, and (3) how this may change under future climate scenarios.
Luke Ettinger, Assistant Professor of Exercise Science
Joint proprioception gives information regarding limb position and movement direction. For shoulder proprioception, quantification of proprioceptive acuity can be achieved through measurement of joint angles during reach-remembered tasks, known as joint position sense. Through collaboration with researchers at the University of Oregon, we created an application for the iPod touch that is designed to measure joint position sense. Using this technique, proprioception from various joints can be measured using minimally invasive techniques, with little to no risk of injury to the participant. Recent studies indicate that proprioceptive acuity of the shoulder and elbow improves as joint angles approach 90 degrees of flexion in the sagittal plane. This finding suggests that external torques may have an influence on proprioceptive acuity as external torque on the arm peaks at 90 degrees. It is unknown what contribution gravitational torques on the arm have on shoulder proprioception. We propose a study to investigate the influences of these external moments on shoulder proprioception through manipulation of external arm torque from either increasing external arm load or by decreasing this moment with submersion of the arm in water.
David Griffith, Assistant Professor of Chemistry
My research is focused on understanding the chemical processes that control the fate of estrogens in aquatic environments using a variety of analytical techniques, including high performance liquid chromatography, UV-visible spectroscopy, degradation kinetics experiments, and high-resolution mass spectrometry. Estrogens are potent hormones that are excreted by vertebrates (e.g., humans and fish) and can enter natural waters through the discharge of treated and raw sewage. Estrogens disrupt the growth and proper development of aquatic organisms at extremely low (sub-ng L-1) concentrations. Yet, we know very little about the distribution and fate of estrogens in rivers, lakes, and oceans. To address this gap, my research group will be conducting fieldwork and laboratory experiments to better understand environmental removal processes, characterize the primary mechanisms driving estrogen distributions, and develop methods to accurately measure estrogen concentrations and potency. The results of our work will be used to predict environmental concentrations, anticipate problem areas, and mitigate the associated risk to aquatic organisms and human health.
Michaela Kleinert, Associate Professor of Physics
2) A brief statement (500 words or less) explaining why you are a good candidate for the position. In this statement you should touch on previous experiences that qualify you for the position, as well as on your career goals after graduating from Willamette.
3) A list of 2-3 Willamette professors who can act as references.
Katja Meyer, Assistant Professor of Environmental & Earth Science
The reduction of oxygen in the oceans, or ocean deoxygenation, is one of many expected impacts of modern anthropogenic climate warming. Because oxygen is essential to all animal life, we are interested in understanding the distribution of marine oxygen changes and the impacts on marine ecosystems. In the Meyer lab, we look at ancient climate warming events to study the relationship between changes in the chemistry of the ocean and the response of marine animal ecosystems. Much of our work is focused on the end-Permian mass extinction, which resulted in the loss of over 95% of marine species and occurred ~252 million years ago. This summer students in the Meyer lab will work on two projects:
1.) Earth system modeling of ocean anoxia: We will use the cGENIE Earth system model to examine the impacts of high atmospheric CO2, enhanced nutrient availability, and changes in the biological pump on the distribution of shallow water anoxia in the end-Permian and Early Triassic. Students will learn how to run model experiments and visualize model output.
2.) Geochemical proxy development: We will work to improve the tools geoscientists have for identifying the presence of euxinic (anoxic and sulfidic) conditions in ancient samples. Using both modern lake sediments and end-Permian rocks, we will examine the size distribution and isotopic composition of pyrite mineral grains found within these rocks as a proxy euxinic conditions. Students will use a variety of lab techniques to prepare samples and examine rock/sediment samples using scanning electron microscopy (SEM).
Chuck Williamson, Professor of Chemistry
In the Williamson research group, we use lasers and other techniques to probe the chemical and physical properties of molecules. One major area of interest for us is the behavior of partially-miscible binary liquid mixtures. These are mixtures of two liquids, such as methanol and carbon disulfide, that are completely miscible above a certain critical temperature, but separate into two layers for certain composition ranges below that temperature. The separated layers, or phases, are also mixtures of the two liquids, but with differing compositions. We use elastic laser light scattering, Raman spectroscopy (inelastic laser light scattering), and nuclear magnetic resonance spectroscopy to study the properties of liquid-liquid mixtures.
This summer our focus will be on elastic laser light scattering. We use elastic laser light scattering to make maps of the macroscopic behavior of binary liquid mixtures. These maps are called phase diagrams, and they show the temperature boundary between one-phase and two-phase behavior as a function of composition. In recent years we have identified a region of the phase diagram that does not behave as expected: a small number of droplets separate out of solution at temperatures slightly higher than the main phase transition. This newly-identified behavior is very puzzling, but it appears to be fundamental in nature because it occurs in the exact same way in at least six different liquid-liquid systems. Our goal for the summer is to learn more about these droplets by clarifying the conditions under which they form, and by hopefully isolating them for chemical characterization. To meet this latter objective, we will need to design and construct a new instrument from scratch.