STUDENT RESEARCH
PRESENTATION DAYS 25TH ANNIVERSARY
Studying the Human Condition IT BEGINS WITH CURIOSITY, PERHAPS ABOUT A TOPIC IN A PREVIOUSLY UNCONSIDERED
field. After many months of discovery, learning, experimenting, failure and more experimenting, seniors find themselves at the front of a room, sharing the results of their investigation during Presentation Days. Throughout the process, they’ve been working alongside faculty experts, grappling with real-world problems, delving into complex issues. This year, there were a number of projects related to human health that captured the interest of senior researchers. 2
mR
0.8 0.6 0.4 0.2 0.0
1
22
mR
1.0
Fraction of Population
Fraction of Population
1.0
0.8 0.6
Weakly-Mixed
A comparison of model results for states of “mixedness,” demonstrating that resistance outbreak can be delayed significantly if the rate of interaction of Weakly-Mixed hospital populations with the general Partially-Mixed community is below a Well-Mixed critical threshold.
Fibrous collagen matrix
Partially-Mixed
0.4
Well-Mixed
0.2
0
0.0
20 0
20
40 60 (years)
40 Time Time (years)
60
80
80
3
1. Modeling the Emergence of Antibiotic Resistance
2. Toric Ideals of Inductively Pierced Neural Codes
3. Antibacterial Chitosan Nanoparticles for a Tissue-Engineered Brain Patch
Student: Colin Okasaki Advisor: Jon Jacobsen, mathematics
Student: Caitlin Lienkaemper Advisor: Mohamed Omar, mathematics
Student: Sakshi Shah Advisors: Tom Donnelly, physics; Liz Orwin ’95, engineering
Antibiotic resistance is a growing international concern, in part due to the rapid emergence of new resistances due to concentrated antibiotic use in environments such as hospitals. Such high use creates a strong selective pressure for pathogens to evolve resistance. Okasaki analyzed strategies hospitals can use to slow the evolution of resistance and built a compartmental ODE model to estimate the length of the delay between evolution and outbreak of resistance. His work supports calls by scientists to decrease the volume of antibiotic use and shows an effective way to delay outbreak.
How does the brain encode the spatial structure of the external world? Place fields were discovered when researchers observed the activity of single neurons in rodents and found that some neurons fired only when the animal was in a specific region of space. Hippocampal neurons, called place cells, become associated to convex regions of space, known as their place fields. When an animal is in the place field of a given place cell, that place cell will fire. A neural code describes the set of firing patterns observed in a set of neurons in terms of which subsets fire together and which do not. Toric ideals are algebraic structures used to study neural codes, and Lienkaemper investigated the extent to which place cell structure can be seen through these toric ideals.
HMC researchers seek to produce chitosan nanoparticles, whose antibacterial properties are essential for the Orwin Lab’s “brain patch,” a tissue-engineered treatment for traumatic brain injury. The patch is made of malleable collagen gel and infused with chitosan nanoparticles. Chitosan, a derivative of chitin, is harvested from shrimp shells and may exhibit anti-inflammatory and anti-bacterial properties. Shah worked on producing chitosan nanoparticles using an apparatus made by Professor Donnelly’s lab in the Department of Physics.
HARVEY MUDD COLLEGE