Summer Research Projects, Department of Physics and Astronomy
Check back occasionally, as the list of projects might change. If you are interested in research opportunities, please click on the links below. We also encourage you to contact the individual department members associated with the projects for further information about the research.
Program Dates
May 26, 2020 - July 31, 2020 OR June 1, 2020 - August 7, 2020Click on the project name for a more detailed description of the project
Project Name: Theoretical and computational modeling of bacteria colony growth
Project Mentor: JiaJia Dong
Project Code: (JD-1)
In the forefront of population dynamics, the pioneering work by Lotka and Volterra in the 1920s sparked the interest in the class of predator-and-prey model in which the survival of each population depends directly on its interactions with the other. Motivated by the rich morphologic patterns found in bacteria colonies, we study a parasite-host type model by using a combination of theoretical and computational tools.
Through this project, you will have the opportunity to:
- study paradigmatic models in population dynamics;
- learn computer programming using Python, a general-purpose programming language widely used in research and industry;
- interact with research scientists and students;
- develop your own project;
- and many more challenging and exciting experiences as a physicist.
Project Name: Mechanics of Actin Networks
Project Mentor: Bekele Gurmessa
Project Code: (BJG-1)
Cytoskeleton is a protein scaffold found inside most eukaryotic cells. It consists of three major classes - actin, microtubules, and intermediate filaments. Actin, the most abundant protein, is a semiflexible biopolymer that plays a crucial structural and mechanical role in cell stability, motion, and replication as well as muscle contraction. Most of these mechanically driven processes stem from the complex viscoelastic response that networks of sterically entangled and chemically crosslinked actin filaments display. This research project combines tabletop experimental work with hands on computer programming skills. While the primary goal is building an optical tweezers setup and developing data acquiring/analysis codes using Matlab and Labview, we will develop optical imaging techniques to study the morphological evolutions of fluorescently labeled actin networks by tuning actin concentration as well as its chemical environment. An interested student will work on all aspects of this project and be exposed to biophysical research from creating in vitro actin networks to building optical tweezers instrument to developing image acquiring/analysis routines that are transferable to any future career path. Prior experience with Matlab or Labview is desirable but not required.
Project Name: Data Analysis and hardware development for the GNOME experiment
Project Mentor: Ibrahim Sulai
Project Code: (IS-1)
The Global Network for Optical Magnetometers for Exotic physics (GNOME) experiment searches for signatures of physics beyond the Standard Model in temporally synchronized time series of atomic magnetometer measurements taken from sensors located around the globe. One of these sensors is located here at Bucknell. The goal of this project is twofold:
- To develop and test high efficiency signal processing and hypothesis testing protocols. For this, programming experience in Python and / or C++ is highly desirable.
- To develop hardware for magnetic field control. This involves some digital and analog electronics.
Project Name: Chaotic mixing, propagating reaction
fronts, and swimming bacteria
Project Mentor: Tom Solomon
Project Code: (THS-1)
In a forest fire, the dividing line between burned and unburned trees is called a front. The motion of this front determines how the fire spreads through the forest. Similar front dynamics characterize the spreading of a disease in society, as well as numerous chemical processing applications, biological processes in cells and developing embryos, and plasmas in fusion reactors. We are currently conducting experiments that explore how the motion of fronts is affected by fluid mixing, e.g., forced flows in a chemical processor, winds in a forest fire, or the motion of people in society while a disease spreads. Table-top experiments using a simple chemical reaction (the well-known Belousov-Zhabotinsky reaction) focus on how fronts are affected by simple flow patterns -- vortices (whirlpools) and jets.
We are testing theories of "burning invariant manifolds" that predict barriers that stop the motion of reaction fronts in laminar (smooth) fluid flows. We have already done several experiments that have verified these predictions in two-dimensional flows, and we are currently extending these experiments to three-dimensional fluid flows.
We have also initiated studies of the motion of swimming bacteria in fluid flows. It turns out that the same theories that predict barriers for the motion of chemical fronts also predicts barriers in the motion of mutated "smooth-swimming" bacteria. We are doing experiments that study these barriers for bacteria swimming in microfluidic channel flows.
There is a lot of "hands-on" work involved in these projects, including the designing, building and testing of the experimental apparatus, mixing chemicals for the reaction, culturing of bacteria, and doing numerous experimental data runs. The experimental work also involves a substantial amount of computer-aided image analysis, almost exclusively on Linux workstations running a program called IDL. We also frequently conduct numerical simulations of the phenomena, also with IDL. Although experience in computer analysis is useful, it is not required as long as the student involved is willing and eager to learn IDL.
This project is intended to compliment theoretical studies of related phenomena (see THS-2 below). There will be daily group discussions/meetings with the theorists (Simon and his student(s)).
Project Name: Effective Swimming Strategies of Bacteria in Fluid
Flows
Project Mentors: Simon Berman and Tom Solomon
Project Code: (SB_TS-1)
Swimming bacteria are hardy creatures that manage to thrive in heterogeneous, ever-changing environments. Remarkably, these single-celled organisms can sense and respond to chemical gradients, allowing them to swim towards nutrients. The basic strategy they use to accomplish this is the well-known “run-and-tumble” motion: bacteria alternate straight-swimming trajectories (runs) with sudden, random changes in direction (tumbles). While this strategy is known to work well when the bacteria swim in stationary fluid, it is not clear how well it works when the fluid is flowing. The fluid flow not only introduces an additional bias into the trajectories of the bacteria, but it may also mix up the chemical gradients they are trying to sniff out, potentially distorting the information they are gathering from the environment.
In this simulation-based project, we will investigate the effectiveness of run-and-tumble swimming in simple fluid flows using a simple numerical model. The project will require programming in Matlab, so previous programming experience will be helpful, but not required. A previous course on ordinary differential equations would also be helpful, but not required. This project is in collaboration Prof. Kevin Mitchell at the University of California, Merced, as well as Prof. Tom Solomon and his student(s), who are performing experiments on swimming bacteria in controlled fluid flows. Hence, there will be opportunities to interpret their experimental data in light of our own results and come up with predictions that they can test in the lab.
Project Name: Jamming of pinned granular materials
Project Mentor: Brian Utter
Project Code: (BU-1)
The stability and flow of materials composed of individual solid grains is surprisingly complicated, exhibiting striking features with implications for both natural phenomena and industrial processing. In these complex systems, many simple building blocks interact through simple nonlinear forces such that complicated behavior emerges, such as the sudden and unpredictable avalanching of a slope of frictional grains or density-controlled rheology in engineered materials.
We perform experiments to study the stresses and particle trajectories of 2d packings of grains under shear. By using a technique known as photoelasticity, grains between crossed polarizers light up under stress, such that we can both determine forces and track particles. The specific project, in collaboration with Professor Katharina Vollmayr-Lee (simulations) and collaborators at Swarthmore College, is to characterize the effect on the stress-strain behavior of inserting immobile pins into a granular array under shear. These experiments will further help us understand the rheology and flow of these materials generally and inform potential applications in which control of properties such as stiffness is desired.
This project will include significant “hands-on” components, such as construction of experimental apparatus, casting of photoelastic grains, data collection, and image analysis to extract and understand quantitative statistics from image sequences of the experimental flow. No specific experience in experiments or programming is required. Please feel free to contact Professor Utter to learn more about this project or see the lab in person.
Clogging of particle suspensions in millifluidic arrays of obstacles
Project Mentor: Brian Utter
Project Code: (BU-2)
The behavior of a suspension of particles pumped through a network of obstacles is governed by a complex, nonlinear interplay of factors. Collections of particles can clog as they squeeze past neighbors through constrictions and the fluid flow readjusts continuously, either trapping additional particles or eroding the clog entirely. The details of this process, particular at the grain-scale, is actually poorly understood, despite applications from petroleum extraction to water filtration.
In this project, we construct quasi-2d channels with arrays of pillars and pump suspensions of 300-micron diameter particles through at controlled flow rate. By imaging the channel (about 6 x 2 cm) with a video camera, we can track individual grains and observe the detailed evolution of clogs that form and dissolve, giving us significant insight into clogging behavior in both space and time.
Preliminary experiments have been completed in prior summers showing proof of concept. The specific goal for this summer is to systematically carry out data collection varying experimental parameters (such as pillar geometry and suspension flow properties) and analyze this data using image processing techniques. This may include casting new channels with controlled pillar spacing, significant experimental data collection, expanding the capabilities of the current analysis programs, and quantifying trends in behavior. No specific experience in experiments or programming is required. Please feel free to contact Professor Utter to learn more about this project or see the lab in person.
Computer Simulation of a Jammed Granular System
Project Mentor: Katharina Vollmayr-Lee
Project Code: (KVL-1)
Examples for granular materials are soap bubbles, rice grains, sand, and snow. They all have in common that the entities (e.g. bubbles) interact and energy is dissipated. At high density granular systems display fascinating phenomena such as avalanches and the jamming transition. In this project we study a system of disks which are packed in between to plates and sheared. In addition to the moving disks are not moving small disks, pins, representing obstacles. We study how these pins influence the jamming transition, the structure (spatial arrangement) and the dynamics of the moving disks. This project is part of a collaboration with the research group of B. Utter, as well as the research groups of A. Bug, and C. Bester in Swarthmore.
The student would work on implementing and running computer simulations using the public software package LAMMPS, as well as working on the analysis of the resulting simulations. No prior computer programming skills are required.
Direct Imaging of Low-Mass Stars and Brown Dwarfs
Project Mentor: Blake Pantoja and Katelyn Allers
Project Code: (BP_KNA-1)
There is rich diversity on the low-mass end of the main-sequence where red dwarfs, the reddest and lowest-mass of stars, meet brown dwarfs, substellar objects incapable of burning hydrogen. Brown dwarfs also bridge stars with planets. These objects are some of the least understood celestial objects, but also are some of the most common, emphasizing the importance of understanding them well. While they can be difficult to detect, especially when gravitationally bound to a bright star, in this project, we will research into the techniques for their discovery. We will also investigate the characteristics of these low-mass objects using tools such as space-based, ground based, adaptive optics, and near-infrared imaging and spectroscopy, while applying evolutionary models and templates to better understand these objects. Prior programming experience in Python / IDL is desirable, but not required.
NSF Sponsored REU Sites
Contact Information:
Professor Tom Solomontsolomon@bucknell.edu