Brown Bag Seminar
The brown bag seminar is a weekly meeting organized by and for graduate students. The goal of the brown bag is to encourage students to practice presenting their work by giving talks to each other in a casual setting.
What are Natural Killer cells doing in cancer?
DateFriday, September 7, 2018 - 12:00pm
AbstractIn recent years, advances in cancer research have shown that the body’s immune response to tumor cells plays a significant role in fighting cancer growth. Whereas the roles of some immune cells have been greatly studied, the role of Natural Killer (NK) cells is less clear. Despite the fact that studies have shown that NK cells are not very effective at penetrating the tumor environment and play a minimal role in the direct killing of tumor cells in a tumor mass, studies with NK cell immunotherapies have shown great potential. This is suspected to occur through metastasis formation. In order to quantify the actual role of NK cells, a model was developed, consisting of 17 coupled ordinary differential equations and one stochastic ODE that capture the complex interplay between the primary tumor, the metastases, and the immune system. All parameters were estimated from experimental data. The model shows that one of the main immune components contributing to the prevention of metastasis formation is killing of circulating tumor cells by NK cells. For tumors with high antigen expression on their surface, T cells play the primary role in preventing metastasis formation, however circulating tumor cells with low antigen expression are eradicated mostly by NK cells. With this model, it is possible to replicate experimental data of metastasis formation under NK cell depletion and treatment with a standard chemotherapy, FOLFOX, for colorectal cancer.
Laser dynamics: Modeling of ultrafast lasers
DateFriday, September 14, 2018 - 12:00pm
AbstractAlthough lasers have been extremely well studied since their first experimental realization in 1960, the advance of modern technology has allowed us to push their limits to new heights, and new speeds. We'll walk through the basic elements of a laser and the history of lasers before delving into one of the most promising modern laser designs, VECSELs, which are capable of producing pulses with kilowatts of peak power and durations of less than 100 femtoseconds. We'll discuss two modeling techniques for these lasers, a classical rate based model and the modern microscopic model, a hybrid PDE model which links Maxwell's Wave Equation to the quantum based Semiconductor Bloch Equations. For the latter model, we'll explore it's successes, complexities, and potential to help develop the next generation of laser technologies.
SIAM Lunch with a Computational Scientist from Lawrence Berkeley National Lab -- Matthew Zahr
DateFriday, September 21, 2018 - 12:00pm
AbstractMatthew Zahr is a recent PhD graduate obtaining his degree in Computational and Mathematical Engineering from Stanford in 2016. He is now the Luis W. Alvarez Postdoctoral Fellow in the Mathematics Group of the Computational Research Division at the Lawrence Berkeley National Laboratory (LBNL). Having received the Department of Energy (DoE) Computational Science Graduate Fellowship, he did at least two summer internships as a graduate student in DoE labs, including at LBNL and Sandia National Lab. And, he works on computational, data science, and uncertainty problems which is a hot research area. Come enjoy informal discussions with him over lunch and get advice about internship/postdoc opportunities, mathematical careers at the DoE, etc.
Does efficiency drive diversity: the optimal distribution of bumble bee workers
DateFriday, September 28, 2018 - 12:00pm
AbstractDiversity among the traits of group member exists within groups, but why this diversity has evolved is not always clear. Bumble bee (Bombus spp) workers exhibit a diversity of body sizes, yet there appears to be no clear colony benefit. Larger workers outperform smaller workers in every respect, so why do colonies produce these small workers? We propose that these small workers benefit the colony despite their worse performance. We test the novel hypothesis that diversity has evolved as a way to increase group efficiency by minimizing opportunity cost through individuals specializing according to their comparative advantage. We test this by modeling the interaction among bumble bee workers based on size-dependent performances and costs from the bumble bee literature. First, comparing the performance of pairs of workers with the same production costs but different amount of diversity. Then we simulate interactions within a colony to determine if colony performance increases with worker diversity.