News Snippets from CMU Physics
May 2017 – Xin Wang earns Ph.D. with thesis on “Elasticity of lipid membrane leaflets"
The biological functions of lipid membranes often depend on fascinating elastic properties which in turn arise from molecular structure: membranes assemble spontaneously from lipid molecules, forming a 5 nm thin fluid film that consists of two individual molecular sheets. This film is hard to stretch but bends easily to adjust its local curvature. And upon imposing curvature, each individual lipid leaflet bends around an internal surface called the “pivotal plane”.
Working with Prof. Deserno, Xin Wang developed precise methods for pinpointing the pivotal plane and in the process discovered a novel method for measuring the so-called "lipid tilt modulus"—a parameter that determines how easily the orientation of individual lipids an deviate from the direction perpendicular to the membrane’s surface. This modulus matters whenever local membrane phenomena are studied, such as membrane pores or inserted proteins. Xin’s work therefore contributes to the ongoing quest to better understand the molecular origin of the fundamental mechanical structures that protect our cells from the environment.
May 2017 – Stephanie O’Neil receives the Physics Department’s RE Cutkosky Award and the JP Fugassi and LE Monteverde Award from MCS
With a double major in physics and creative writing, Stephanie O’Neil is now leaving CMU where she has been a dedicated student and researcher, as well as an active member of the campus community. With the Dr. J Paul Fugassi and Linda E Monteverde Award, MCS recognizes the graduating female senior with the greatest academic achievement and professional promise. The Richard E Cutkosky Award is presented each year to an outstanding graduating senior in the physics department.
Beyond her flawless academic record, Stephanie was a whirlwind of activities as a member of the Kiltie Band, the Flute Choir, the All University Orchestra, as well as the Physics Steering Committee, the secretary of the Astronomy Club and a tutor in the Physics Upper Class Course Center. Last year, she was the undergraduate representative for the MCS college council. In undergraduate research, she has been studying dwarf galaxies with Assistant Professor of Physics Matthew Walker. In this work, she focused on inferring dark matter contents of dwarf spheroidal galaxies that orbit our milky way. Stephanie was also greatly appraised by her faculty mentors as REU (Research Experience for Undergrad program of the NSF) scholar at William & Mary and at MIT in the summers of 2015 and 2016. After graduation, she will join MIT’s Kavli Institute for Astrophysics and Space Research to pursue a Ph.D. in astrophysics.
May 2017 – Krista Freeman earns Ph.D. with thesis on “Viral DNA Retention and Ejection controlled by Capsid Stability”
Viruses are submicroscopic pathogens that infect every branch, twig and sprig of the tree of life. They consist of little more than a genome stored inside a protein shell, called the capsid, and exploit the cellular machinery of the organisms they infect for their own replication. Many bacterial viruses, and also some human ones, store their genome under enormous pressure in the capsid—more than 10 times that of an inflated car tire. Because such genomes consist of DNA that is several hundred times longer than the size of the capsid, the highly charged DNA strand must be very tightly squeezed to fit in. Upon infection, the capsid opens up and the DNA gets ejected into the host cell much like a jack-in-the-box.
In her thesis, Krista investigated the time course of this dynamic process and the physical principles underlying the construction of capsids that can withstand such enormous pressures. Besides gaining fascinating insights into these genome-loaded nano-machines, such studies also touch upon basic medical concerns: understanding the physical mechanisms that viruses rely on may open new avenues to combat them. And since this invokes general physical principles, the virus may not easily be able to respond with adaptive mutations.
May 2017 – Sidd Satpathy receives Hugh Young Teaching Award
As a teaching assistant (TA), Siddharth Satpathy, a Ph.D. candidate in the Department of Physics, is described as conscientious, compassionate, dedicated, nurturing, and helpful – in short, “one of the best TA’s ever” by students and faculty alike. During the last three years, Satpathy – better known as Sidd – has taught five different sections of the introductory course Physics for Science Students and Calculus in Three Dimensions, the latter for the Department of Mathematical Sciences. Sidd also served for two years as an instructor in Carnegie Mellon University’s Summer Academy for Math and Science for high school students.
In recognition of his enthusiasm for teaching and his unyielding dedication to going above and beyond for his mentee students, Siddharth Satpathy has been awarded the 2017 Hugh Young Graduate Student Teaching Award. Congratulations, Sidd!
April 2017 – Belle II Project at KEK in Tsukuba/Japan
The Belle experiments study collisions of electrons and positrons at a total energy of ~10 GeV. This energy is chosen to produce B mesons: particles composed of a heavy "bottom" quark and a light anti-quark. These are of special interest since they violate "CP symmetry", that is, they differ in the behavior of matter and anti-matter. This asymmetry poses one of the deepest mysteries of particle physics, and solving it may shed light on the unexplained observation that the Universe is dominantly made of matter, rather than anti-matter. Belle II is an improved version of the very successful first Belle experiment and aims to collect a larger data samples with an improved detector.
CMU is involved in a variety of activities at Belle II: Prof. Roy Briere is co-chair of the charm physics analysis group, exploring the physics reach and planning analyses on these topics. Postdoc Jake Bennett is data production coordinator, overseeing production and processing of simulated Monte-Carlo samples and preparing for real data-taking in the near future. Together, Jake and Roy are also responsible for calibrating dE/dx measurements from the CDC wire chamber, one of several methods employed to distinguish the identities of the various particles measured in the Belle II detector.