Author Archives: Iris Chang

Farewell to my PFD

Canoeing on the Eno River this summer was such a fun albeit exhausting experience. A term that I learned, courtesy of Dr. Grunwald, is PFD: personal floatation device, a.k.a. life vest. (Being a swimmer since my youth I’d have expected myself to know the acronym, but I didn’t.)

Rebecca and I preparing to canoe with our personal floatation devices! (We did not flip over!)

For me, BSURF was a little like my PFD for research— a constant that I could allow myself to lean on and return to while I was dipping my feet in the waters of research: Jason’s wonderful breakfasts, inspiring faculty talks, daily seminars on how to ask good questions and communicate science with integrity, reassuring friends who, more or less were on the same shallow shores that I was. Coming into the program, I relied heavily on this PFD to explore a new avenue I’ve never dove in before. There existed in me an optimist who was unsure of what to expect but was eager to learn as much as I could, but I was also shadowed by the fear of the ever-present pessimist, crafted from the lack of knowledge of what I wanted to do in the future.

Each body of mind was proved a little bit right and a little bit wrong. No, I haven’t finalized the main mechanism of Traumatic Brain Injury or calculated a new head injury criterion, but yes, I have learned so much about the ongoing conversation in this field and have immersed myself in tools like LS-DYNA, LS-PrePost, and the SIMon model that allowed me to understand TBI more. Yes, some days were slow and sometimes stagnant, but other days with pig dissections and drop testing prep were incredibly exciting.

I pushed myself to tackle challenges, ask question, be vulnerable, and most importantly, find joy. I found joy in lab, listening to the many jokes that Dale always makes during lab meetings and being touched by the genuine care and crazy intelligence of lab members. No matter where I end up in the future, the aura of this lab, this biomechanics family, will always set the standard anywhere I work. And I found joy outside of lab, making wonderful memories with old and new friends whether playing games late at night, teaching kids about snakes at the Eno River Festival, or going out on food excursions across Durham.

I want to thank Dr. Dale Bass, Chris Eckersley, Jason Luck, and the rest of the biomechanics lab for being wonderful, inspiring mentor figures and co-workers during my time in lab. Also, I’d like to thank Dr. Ron Grunwald, Jason Long, and everybody in BSURF for being a part of my PFD in the entrance to the large and rather scary ocean of the future. Now that eight weeks have passed filled with rises and falls and a lot of learning, I believe it’s time to say farewell to my PFD. Coming in with only a broad idea of what I want to do in the future, BSURF has given me so much insight on which paths I want to start pursuing as I grow older.  I am grateful for everything that BSURF has provided me with; such opportunities and privileges, though I say farewell, will never be forgotten.

My fabulous poster! Also, shout-out to Dale for the iPad videos idea!

Moist Toilet Paper

Dr. Charles Gersbach wakes up each morning motivated and excited by the thought that he can discover something new and fresh with his passion and hard work.

He didn’t feel he could find such motivation through moist toilet paper, an idea proposed by Kimberly Clark, or through transfecting cells everyday to protect toddlers from RSV infections.

Of course, both moist toilet paper and cell transfections are important in their own ways, but Dr. Gersbach felt like he was simply “one little cog in a bigger machine.”

However, once he tasted the side of academia by experiencing a bone growth product, he found a new love and freedom for lab. His idea of what “engineering” meant shifted, especially for cutting edge research.

Now, Dr. Gersbach works with CRISPR and Genome Editing to decipher the dilemma of muscular dystrophy and attempts to differentiate between gene editing and gene therapy to capitalize, understand, and edit the dystrophin protein holding together muscle cells. As an aspiring engineer fascinated with CRISPR and genome editing myself, I was extremely interested in how he tackled the gene editing portion and how he found the balance between engineering and biology.

Dr. Gersbach fought a dilemma that I find myself facing; industry v.s. academia. His insight into how he felt with his experiences in industry versus the freedom he finds through academia proves extremely helpful as I attempt to figure out what I want from the future. Thank you Dr. Gersbach for a wonderful faculty talk!

Mild Traumatic Brain Injury

Mild Traumatic Brain Injury (mTBI): Role of rotational kinematics through the mechanism of shear shock

ABSTRACT— Despite decades of research, the exact mechanism in mild Traumatic Brain Injury (mTBI) remains unknown. The purpose of this study was to determine whether rotational velocity or acceleration is the primary contributor to mTBI and explore the effect of shear shock waves generated from rotational acceleration. It was hypothesized that rotational acceleration, not rotational velocity, has a primary role in mTBI, and shear shock waves due to the nonlinear pressure waves are a mechanism for mTBI. This study was conducted with a dual modeling and experimental approach. First, strain and deformation response was observed and recorded through the finite element analysis Simulated Injury Monitor (SIMon model). These results were then compared to deformations and strains recorded during pig brain rotational impacts using three dimensional imaging analysis. So far, the simulations reflect the relatively lower strain and stresses created through rotational velocity. Results indicate that rotational acceleration through the mechanism of shear shock waves is a prevalent mechanism in mTBI and could largely alter how future head injury criterions are created and how protective gears for sports players and the military are crafted.


On An Educational Analysis of Poop

When one of my friends first mentioned that he literally did not want to leave his bed sometimes in winter and could have a case of seasonal depression, I was awfully confused.

Seasonal depression? In my mind, depression couldn’t be seasonal; there wasn’t a switch where one could turn “on” or “off” depression.

So, curious, I looked into it, and found that during winter, the change in hours of light can modify one’s biological clock and therefore shift hormone levels of serotonin and melatonin (regulators of mood and sleep, which are correlated with depression) (Lieber). I thought it was fascinating that our own environment could change our bodies and how we feel.

I drew upon this memory when listening to Georgia, a fellow B-SURFer, on her talk Stress and Weather: Environmental Factors Affecting Glucocorticoid (GC) Levels. Her lab studies baboons and how not only their social rank but also their environment in Africa contributes to stress. They extract hormones from baboon fecal samples in order to analyze how the environmental factors recorded correlate to glucocorticoid levels (and therefore stress). Her hypothesis was that GC levels would increase as environmental factors became more extreme, and I completely understood when she referred to the different types of food distributions: scramble and contest. In my senior year of high school, I participated in an international written and oral debate contest on the topic of global food security. Through all the research on global food security and relating topics, I understood the food access, availability, and distribution issues that are quickly rising in the world today. With such different food models dispersed around the world and the advent of climate change, stress levels could vary greatly. I’m very curious as to how exactly these increased stress levels will create side effects that weren’t originally conjectured—perhaps in reproductive stress/hormones? Our levels of health, like seasonal depression? I was very enlightened with Georgia’s work and hope to hear about results or possible new leads soon!

Normal Termination

Hudson Hall is usually chilly when I walk in. I take the steps all the way to the back, the path once a maze but now familiar, up the stairs, and into the Annex. I check in with my graduate mentor, Chris, and ask for updates and any tasks to accomplish for the day. I check LS-DYNA and Pre-Post, hoping for the words that signal that the SIMon model I altered has successfully completed: Normal Termination. I check my lab book and Excel spreadsheet for what I’ve already tested and look through the resulting animation, clicking through tabs for any sign of possible changes I can make. Analyze the strain on the finished model, check for global rotational velocity, alter kinematic curves, and re-run the program.

Recently, pace has picked up. I head down to the basement to work on impact testing for the pig brain, and ask questions about the process, trying not to feel small in a world of complex materials and knowledgeable mentors. On test day, I go in early to prep the drop track, double checking the electromagnet and the camera. We (my grad student, PI, and a couple other grad students) head over to the medical center in order to pick up pigs they have finished working with. After a dissection and removal of the skull, we attempt to make a clear skull using hardener and plaster while doing drop tests in the basement on the brain with no skull. Save the videos and call it a day!

There is a friendly aura that surrounds everybody working in lab: an impalpable feeling that introduces peace on stressful days. I am always appreciative of the smiles and genuine care the mentors in lab have toward all the students, even while pushing us toward challenges and hard work. So this is lab: tinkering and Error Terminations on a quiet day, advances in the model, lab meetings, impact testing, and Normal Terminations on a good day.

Normal Termination!

The Game Plan

Anybody who knows me relatively well will know that I am a huge pro-football fan (33 days till Hall of Fame Game Cowboys vs. Cardinals, but who’s counting?) But many fanatics, myself included, often severely overlook the risks that athletes take when they play sports: traumatic brain injury one of many not yet fully understood. Brain injury extends far from sports, however, including military implications and even normal day life—surprisingly, motor vehicles are only the third leading cause of traumatic brain injury (TBI), landing behind ‘falls’ and ‘individual being struck by another object’ (Meaney 2). 

Dr. Bass’ Injury and Orthopaedic Biomechanics Laboratory seeks to dig deeper into different aspects of brain injury; my mentor Chris and I hope to investigate the key mechanism of TBI. Currently, two branches of ideology exist in regards to how mild traumatic brain injury arises; the first believes that mainly direct impacts to the head, linear velocities and accelerations, are the key mechanisms of head injury and the second school conjectures that rotational velocities and accelerations cause head injury. A plethora of experiments (Gennarelli, Euckerhave concluded that head rotation is the greater cause of mild traumatic brain injury, but the exact mechanism of TBI, whether angular velocity or acceleration and whether parameters to measure concussion include shear strain, relative displacement, shear stress, pressure waves, etc. remains to be confirmed. Currently, some of the main parameters used to determine and assess level of brain injury are cumulative strain damage measurements (CSDM), maximum principal strain (MPS), and maximum pressure.

This summer, a twofold process will be used to analyze the true mechanism that is causing shear and strain in the brain. First, a program called LS-DYNA/LS-PrePost will be used to analyze the finite element analysis SIMon model. The SIMon (Simulated Injury Monitor) was made to evaluate injury potential by directly imposing measured responses on a finite element model, which allows deformation and predicts how a product reacts to real world forces.

Using finite element analysis to model reactions to real world forces, such as a ball hitting a plate with a set velocity.

SIMon Model to analyze effects of rotational velocity on the brain

Second, a gel will be used for hands-on experimentation. A built device will allow different accelerations and constant velocities to be manually created and the resulting strain will be reflected in the gel—different colors (similar to figure 4) will appear and can be compared to the strains found from the SIMon model. Although the materials are different (SIMon model set brain material versus brain-like gel), the strains should reflect relatively the same values.

Finally, an experiment will be conducted to attempt to understand the effect of shear shock waves on the brain. Currently, the exact effect of instantaneous pressure waves and energy mounts from shear shock waves (hemorrhages, microcavitations, etc.) is unknown. In order to visualize injury that MRI scans usually cannot pick up on, the same device as the gel experiment will be used to give impact to a pig’s brain. Different boundary conditions will be placed; the pig’s skull will be replaced with a clear, transparent, skull cap in order to visualize the interior of the brain during the impact. Analyzing the effects of shear shock will allow better understanding of how these waves truly contribute to traumatic brain injury. Although the ideas are still preliminary, by the time NFL season rolls around, I hope to have delved deeper into my research project and reaped some interesting results!

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Don’t Pigeonhole Yourself

Pigeonhole: (verb) 1. the act of placing someone in a category as narrow and confined as a literal pigeonhole is

Advice from Dale to adventurers like myself in science: “Don’t pigeonhole yourself.” There is always a tendency and social stigma to stay relatively fixed on a path, but the path can change. “Be free, science is all about freedom.” Dale briefly recounted the story of the cosmic microwave scientists who won the Nobel prize after simply stumbling upon a noise that was actually radiation from the universe! It proves that life is full of twists, turns, and surprises; including his own.

Dr. Cameron ‘Dale’ Bass, PI to the fabulous Bass Injury and Orthopaedic Biomechanics Laboratory, grew up not only in North Carolina, but also in Belgium, where he attended the International School of Brussels before returning to earn his Bachelor’s and Ph.D. in Aerospace Engineering at the University of Virginia. Even though there always existed the dream of becoming an astronaut, Dr. Bass decided to stray from his seemingly set path and received his postdoc in Biomechanics. The big dream is to one day discover the cause and genesis of brain injury. He discusses a scenario where somebody is punched—in the 200 milliseconds after the punch, where does the brain switch from the conscious to the unconscious? Dale also shared with me a time in lab when he was at the University of Virginia. Their team had ran their impact test on thousands and thousands of dummies and even several cadavers in preparation for a huge showcase for an automobile company. On the day of the display, hundreds of spectators, including the automobile company, showed up to see the cadaver impact test, but one at a time, different aspects of the set-up began to fail and nobody knew why! His experience simply confirms the ideas of luck, failure, and persistence within science.

While Dr. Bass would love to have dinner with Albert Einstein and Niels Bohr, I was simply lucky to sit down and talk with him for a few precious minutes. I am always smiling and laughing while talking to Dale, but just as important, always learning and ready to learn more in his lab!

Dale Bass!

CT Scans Aren’t Just for Doctors

A textbook can give me the equation for principal stresses and the Young’s Modulus for a 6061-Aluminum shaft, but it can’t give me the experience of working with cervical spines and human brains. Joining Dr. Bass’ Injury and Orthopaedic Biomechanics Laboratory, I was at first apprehensive of what I would exactly be doing, but excitement and fascination quickly consumed any nerves as I witnessed Micro CT scanning in action and learned the basics of the LS-DYNA finite element analysis modeling program.

The optimist residing in me hopes to reap results that will be new, fresh, and add to the ongoing scientific conversation in this biomechanics field. There is always the exciting dream of discovering the true mechanism behind concussions, or designing a program that can take individual measurements and parameters and custom-make football and military helmets. The realist in me doesn’t expect to even come close to those long-term goals by the end of my BSURF summer, but definitely wants a deeper understanding of the parameters that affect head injury; be immersed in several new terms, tools, methods, and skills that will allow me to fathom how linear and angular velocity and acceleration play into mild traumatic brain injury. And of course the pessimist exists, though ever so tiny, always the fear that I don’t have enough knowledge to experiment, program, and actually gain results and make even the slightest difference. Already, I have experienced the frustration of modelling and switching up the slightest of parameters just to have the program fail again. All three bodies of mind comprise my expectations and aspirations for my summer research, and ideally their balance will mold an eventful summer.

After this first week, I think I’m finally getting my head wrapped around how much failure or stagnation in research can be constant and prevalent, and I think I understand what the meaning of research entails. There is no step-by-step lab manual given, no known value to try and match, no black and white; there is simply the unknown, the questions, and the scientists brave and vulnerable enough to chase after answers.

On a less technical note, I want to find as much joy as I can. This is my first real college research experience, and I want to make the most of it, regardless of the results I get. I want to make connections with lab and Fellowship members and  gain life advice and experience from coworkers, mentors, faculty, and friends. Having fun, crafting timeless memories, and making lifelong friends are always at the top of my agenda!

Using LS-DYNA and LS-PrePost to analyze a brain model for head injury!