Yohei Takano is a 4th year graduate student whose line of research involves working with Dr. Takamitsu Ito on understanding large-scale ocean biogeochemical cycles, including dissolved oxygen, nutrients, and carbon cycles. The main focus of his research is to understand how ocean biogeochemical cycles responds to climate variability and long-term climatic change, such as global warming. Currently, Yohei is working on understanding how oxygen minimum zones evolve under the inﬂuence of human induced climate change, which could involve both physical and biological response in the ocean.
Before coming to Georgia Tech, Yohei obtained an M.S. in Atmospheric Sciences from Colorado State University. He says that training from the atmospheric science ﬁeld really helped him on developing interdisciplinary understanding and research approach on coupled processes between climate change/variability and ocean biogeochemical cycles.
During his spare time he enjoys cooking and eating. Yohei says cooking helped him communicate with people from different cultures and he loves to share recipes with his friends. Most recently, Yohei is wrapping up his research for publications and his dissertation.
Lujendra (Luju) Ojha is a 3rd year PhD student in Planetary Science with a Volcanology minor. He received his BS in Geo-physics with a Planetary Science minor from the University of Arizona in 2012. With his advisor Dr. James Wray, his main research interest is understanding the evolution of terrestrial planets. He’s passionate about studying present day geological features on planetary bodies across the solar system. Luju has worked on Earth, Mars, Moon, asteroids, comets, and has also classified various meteorites. His greatest accomplishment to date was discovering streams of water on Mars, by understanding the formation mechanism of Recurring Slope Lineae (RSL).
Mr. Ojha has several peer-reviewed publications and awards which include a Research Excellence Award and Lunar and Planetary Institute Career Award from the National Science Foundation. When he was at the University of Arizona he received an Honorary Presidents Award and placed first in the Physical Science Research Annual Student Showcase.
Most recently Luju has gone to France for a month long NSF-GROW Fellowship.
Pamela Grothe is a 4th year PhD candidate currently researching paleoclimate - reconstructing tropical Pacific climate through the last 6,000 years using geochemistry from fossil corals. She received a B.S. in geology from Mary Washington College, an M.S. in geology from the University of Colorado and was a part of the Sigma Delta Epsilon/Graduate Women in Science Fellowship for the 2014-2015 academic year. Pamela currently has a paper in review in G-cubed titled, "A comparison of rapid-screen 14C and U/Th dates: Implications for paleoclimate reconstruction."
For her current project, she is reconstructing the El Nino Southern Oscillation (ENSO) between 2000 and 6000 years ago from fossil corals from Christmas Island, central tropical Pacific. Future projections of the strength of ENSO, the largest source of year-to-year climate extremes, are highly uncertain. The instrumental record of ENSO activity is too short in time to resolve potential anthropogenic trends in ENSO properties. Coral oxygen isotopes, alternatively, provide monthly-resolved ENSO activity, and extend back 7000 years ago from islands in the central tropical Pacific. Pamela says her initial results suggest a ~60% reduction in ENSO activity between 3000 and 5000 years ago. She goes on to say, “This work is significant as it will allow us to uncover mechanisms behind past ENSO variability and refine simulations of ENSO in climate models.”
In her spare time, Pamela enjoys running, biking, swimming, hiking, camping, kayaking, and SCUBA diving. She also exclaims, “I love my yellow lab rescue dog, Cooper!”
The ultimate fate of materials in soils and sediments has relevance to both contaminant transport processes and global biogeochemical cycles. Consequently, we focus on the transformation of specific species in these subsurface environments. Chromium has become the second most common metal contaminant in the United States because of its utility in many industrial processes motivating us to study the stability of chromium containing solids. Furthermore, we are interested in unraveling an unclear process involving silica that occurs in marine sediments and may directly influence ocean pH.
Before returning to school to complete her B.S. in Chemistry at Georgia Tech (2010), Emily worked on various organic farms assisting in the development of sustainable farming practices and also at USU’s Water Research Lab collecting data for hydraulic and habitat simulations. Emily moved to New Zealand before entering into and completing an M.S. program in Chemistry at Northern Arizona University (2013). Emily is now working towards a PhD with Dr. Yuanzhi Tang and enjoys live music, tap dancing, and teaching step aerobics.
My research aims to understand the thermal evolution of pyroclastic flows during a volcanic eruption. Pyroclastic flows are composed of hot gas and rocks, and are fast moving currents that propagate due to the density differential between the flow and the ambient atmosphere. Due to the hazards and inability to see within a pyroclastic flow, we do not know how the temperature of the flow evolves or how particles are concentrated. Therefore, we do not fully understand the associated dynamics and hazards. I use multiphase numerical models that are constrained with field data and observations to study the internal physics and dynamics of the pyroclastic flows. I specifically work to examine the thermal evolution in order to constrain the concentration of particles and efficiency of the flows to entrain colder ambient air during the 2006 eruption of Tungurahua volcano, Ecuador.
Mary graduated summa cum laude from Mesa State College in Grand Junction, CO with a B.S. in Geology. She then did a one-year post-baccalaureate internship at Los Alamos National Laboratory. She is currently finishing up her Ph.D. in Dr. Dufek’s volcanology group and serves as the chair of the Graduates in EAS group. Mary received the Department of Energy Computational Science Graduate Fellowship and National Science Foundation Graduate Research Fellowship. In her spare time, Mary enjoys running, hiking, volunteering, and traveling.
My research focuses on the interactions between nitrogen and methane cycling in a northern latitude peatland in northern Minnesota, the site of the DOE Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) experiment. SPRUCE is a large-scale mesocosm project studying the effects of increased CO2 and temperatures on a nutrient-poor peatland ecosystem. Peatlands and permafrost regions have gained increased interest due to the predicted rise in temperature expected to impact these regions in the next century. The future of peatland’s role in the sequestration or release of carbon to the atmosphere is uncertain. For my Master’s research, I measured spatial and temporal variation in nitrogen fixation rates under varying temperature and methane concentrations for SPRUCE peat samples. My PhD research will investigate the response of microbial nitrogen and methane cycling to warming and elevated CO2.
Melissa I graduated cum laude from Kennesaw State University in Kennesaw, Georgia with a B.S. in Biology. She serves on the student committee for the 2015 Southeastern Biogeochemical Symposium and is currently completing her Master’s work in the group of Dr. Jennifer Glass and will begin her PhD in the summer. Dr. Joel Kostka and Dr. Chris Schadt (ORNL) are members on her Master’s committee. When Melissa is not working on her research, she can be found anywhere outside, running, hiking, horseback riding, and relaxing with friends and family.
The amount of volatiles and the dynamics of bubbles play a significant role on the transition between different volcanic eruption behaviors. The transport of exsolved volatiles through zoned magma chambers is complex and remains poorly constrained. Salah, in his PhD study, mainly focuses on the different transport of volatiles under two end member regimes: crystal-poor systems (bubbles form a suspension) versus crystal-rich reservoirs (multiphase porous media flow). To contrast the differences between the transports of exsolved volatiles in both regimes, the transport of a non-wetting phase in suspensions and porous media are characterized, separately, and then the effect of the transition zone on the over all flux is taken into account.
Investigating the dynamics of multi-particle systems to correctly integrate the effect of particle interactions on the rheological, mechanical and thermal properties of condensed matter is another aspect of his research interest.
Salah completed his B.S. in Mechanical Engineering at Urmia University (Iran) in 2009, his M.S. in Mechanical Engineering at Sharif University of Technology (Iran) in 2011, and recently completed another M.S. in Earth and Atmospheric Sciences at Georgia Tech.
The overarching goal of my research is to characterize and quantify the dynamics of subaqueous explosive volcano (aka Neptunian) eruptions. Neptunian eruptions are far less understood than their subaerial counterparts, yet equally hazardous. This discrepancy arises due to the near impossibility of collecting real-time eruption data. To gain insight into these systems, I am developing a multiphase fluid dynamics model, as well as a Neptunian Eruption Simulation Tank, to simulate (1) how fragmentation occurs (2) how material and heat are transported/deposited, and (3) how tsunamis are generated, during these eruptions. The overall goal is to use the model in concert with the experiments and field data to reproduce the 2012 eruption dynamics at Havre Volcano, New Zealand, the largest observed submarine eruptions in the last century.
Ryan graduated with Honors from the University of Texas at Austin with a B.S. in Geology. In 2012, Ryan received the Outstanding Student Paper Award at the American Geophysical Union meeting. He currently serves as chair of the Graduate Student EAS Seminar committee and organizer of the Geophysics Seminar. In Ryan's free time he enjoys brewing beer, watching/playing sports, and general adventuring.
I investigate the complex interactions between the solar wind and outer planet magnetic fields using sophisticated computer simulations. Planetary magnetospheres exhibit a wide variety of phenomena, thus functioning as natural laboratories in which we can investigate the behavior of magnetized plasma under different conditions. Understanding magnetospheric conditions is also vital to planning spacecraft missions, as high energy plasmas can pose a substantial radiation hazard. My thesis research focuses on understanding the global implications of the production and transport of new plasma in Saturn's magnetosphere. The presence of the Cassini spacecraft in orbit around Saturn provides us with valuable data with which to validate our results and develop our numerical tools.
Ashok completed his B.S. in Mechanical Engineering at Cornell University in 2006 and his M.S. in Mechanical Engineering at Georgia Tech in 2011.
My research interests revolve around developing sustainable solutions for environmental problems by utilizing the symbiosis between humans and nature. In the Taillefert lab I study how we can use uranium-breathing bacteria to clean up uranium-contaminated groundwater at nuclear facilities. Cost-effective remediation strategies that address nuclear waste spills are necessary to ensure that nuclear power is a safe alternative to fossil fuels. My dissertation investigates the duality of uranium as both a toxic contaminant and an energy source for bacteria and the geochemical conditions that control the fate of uranium in the subsurface.
Keaton completed his B.S. in Earth and Atmospheric Sciences at Georgia Tech in 2010 and recently received the Best Talk Award at the 2013 EAS Graduate Student Symposium. He currently serves on the steering committee for the Southeastern Biogeochemistry Symposium and is the founder and organizer of the Careers in Science seminar series. Outside of the lab, Keaton can be found throwing pottery, globetrotting, or rocking out to live music.