Physics & Astronomy | College of Science
Machine-Learning Based Background Rejection Software for the HAWC Gamma-Ray Observatory
Udara Abeysekara, Research Assistant Professor
The High Altitude Water Cherenkov (HAWC) observatory is designed to observe high-energy gamma and cosmic rays. When high-energy gamma and cosmic rays enter the atmosphere, they interact with air molecules and generate extensive air showers (EAS). HAWC measures the arrival direction, energy, and the lateral distribution of the particles in the shower. The energy and the arrival direction of the primary gamma/cosmic rays are derived using this information. The primary interest of our group is to use HAWC to observe gamma-rays. Therefore, the events generated due to cosmic rays, our background, need to be removed from the data. However, the ratio of triggered gamma-ray events to cosmic-ray events is 1 to 1000. Therefore, a good background rejection algorithm is necessary to detect gamma-rays. HAWC currently uses a simple linear selection filter, which is based on the particle clustering along the lateral plane. Our studies of simulated data show that other information, such as the charge distribution, and arrival time of particles can improve the background rejection algorithm. However, the selection filter becomes nonlinear when we add more parameters, and becomes impractical to define an analytical formula as a selection filter. Therefore, our group applied a Boosted Decision Tree (BDT) algorithm implemented using the TMVA package to derive a machine learning based cut. Preliminary studies show that the machine learning algorithm can improve the background rejection by about 20%. We propose that an undergraduate student apply the python based scikit-learn machine learning tool, an industry standard, to improve the background rejection algorithm..
Biology | College of Science
Optogenetic interrogation of sensory processing in the brain
Dimitri Traenkner, Research Assistant Professor
By combining a newly developed direct and quantitative stress-response test for mice with pharmacological silencing of small brain volumes, I have recently discovered an unexpected role of the forebrain in novelty detection. Silencing the forebrain abolishes the ability of mice to show the normal elevated stress response to an unfamiliar stimulus. This observation suggests that the mammalian forebrain tags an unfamiliar stimulus as novel and triggers alertness. It is possible that forebrain novelty-tags also trigger higher order processes, such as learning and memory formation. The undergraduate research project is designed to further explore the role of forebrain activity in novelty processing using optogenetics. With channelrhodopsin, an engineered light-controlled ion channel, we will artificially induce neuronal activity in the forebrain and study the effect on stress responses, learning, and memory formation.
Physics & Astronomy | College of Science
Vikram Deshpande, Assistant Professor
The discovery of graphene and subsequent Nobel prize has given rise to the rapidly growing field of materials that only one atom thick. These materials go beyond the metallic graphene to include semiconductors, insulators, magnets, superconductors and other diverse forms of matter. The proposed projects builds atomically thin heterostructures or "sandwiches" between disparate atomically-thin materials to create new designer materials and designer properties. Examples include graphene/insulator, graphene/superconductor, topological insulator/magnetic insulator, topological insulator/superconductor and many others. Undergraduates get hands-on experience to do cutting-edge science. There are two particular projects for which I am looking to recruit undergrads:
- Since atomically-thin materials are also very stretchy, we will strain them and study modified properties.
- Certain atomically-thin materials are very sensitive to the environment. So we will come up with way to build heterostructures using them in controlled environments.
Chemistry | College of Science
Hairy Nanoparticle Solid Polymer Electrolytes For Lithium Ion Batteries
Ilya Zharov, Associate Professor
This research project will be a part of Zharov group effort in the area of alternative energy. As the world becomes increasingly reliant on mobile electrical power, batteries play an ever-greater role in all aspects of our life. Today's batteries are expensive, often unsafe and, in addition, too heavy to be used in portable devices that require high battery power. There is great need for batteries which do not incorporate liquid organic solvents, which could revolutionize battery technology because of their promising properties including nontoxicity, ease of preparation, stability during operation, and enhanced safety. The major limitation of solid-state batteries is their low power densities compared to those of liquid-electrolyte batteries. This is due in large part to the low ionic conductivity of the solid electrolyte.The goal of this project is to design novel nanocomposite solid polymer electrolytes, which will afford batteries with long service life and innovative functionalities. Specifically, we will prepare Li+ polymer electrolytes composed of polymers grafted on ion-conducting inorganic nanoparticles. Such electrolytes have never been synthesized. Therefore, it is essential to prepare and study these materials in terms of the effect of different polymer brush architecture, the type and content of lithium salt and the composition of the inorganic nanoparticles on the structure and ionic conductivity. We expect that these novel polymer electrolytes will possess particularly high ionic conductivity which will provide excellent performance in all-solid lithium-ion batteries.
Biology | College of Science
Determine the high-resolution structure of octahedral polyomavirus by cryogenic electron microscopy
David Belnap, Research Associate Professor
Viruses are biological entities that encase a genome in a protective membranous covering or protein shell. The coverings or shells are found in a large diversity of shapes and sizes. Polyomaviruses are viruses that infect humans and many other animals. The capsids of polyomaviruses are made up of protein VP1. This protein has the unusual ability to form shells of different shapes. Different shapes are formed by treating the protein under different chemical conditions. One shape that can be formed is an octahedral shell. We will grow VP1 in bacteria, harvest the protein, form octahedral particles, and image particles by cryogenic electron microscopy (cryo-EM). Cryo-EM will include two-dimensional imaging followed by three-dimensional image reconstruction of the octahedral structure. Finally, we will model the atomic-resolution structure of the octahedral form and compare it to other known forms. This study should enable us to better understand how polyomavirus VP1 is able to form such divergent shells.