School of Graduate Studies

School of Graduate Studies
School of Graduate Studies

Cara Yin during her final presentatoin"Shine a Light: 3MT Champ shows the potential

of laser beams in making surgery safer."

By Sharday Mosurinjohn, April 2015


Chenman(Cara) Yin is a physicist’s physicist – she switched from astrophysics, the program for which she’d come from China, to engineering physics because the former was too “remote from reality” for someone who is more motivated “by solving hands-on problems.” In exploring the hardest of the hard sciences, she wound up working with an equally hard material, bone. In her Master of Applied Science under the supervision of Dr. James Fraser, Yin is researching how to use lasers to cut bone in hopes of making procedures like brain surgery safer. Her presentation of this research for Queen’s 2015 Three-Minute Thesis (3MT) competition won her first place and a spot at the provincial competition to be held at Western University later this month.

The laser cutting technique, which lets you measure and control the depth of the cut in real time, is extremely precise, more so than even the steadiest surgeon. This is because a laser – which, you may not realize is actually an acronym standing for “Light Amplification by Stimulated Emission of Radiation” – amplifies incoming light through a pair of mirrors and the “gain medium,” which can be an orderly crystal or even a gas like carbon dioxide. The amplified light is of a single frequency (or colour) and can be focused very tightly by a lens to generate a high energy beam to cut material. An incredible side effect is that the imaging light scatters into the surrounding tissue, which, once close to the threshold between the skull and the brain, also lets the operator see where that delicate brain tissue starts in order to protect it. The laser is controlled by a computer program that allows you to program the depth of your cut down to the micron.

For her 3MT visual, Yin showed an image of bone – a piece of a cow’s tailbone procured from the grocery store – incised with the Queen’s logo. What it took was to change the insignia into a black and white image and then to tell the computer that the black parts should be, say, one millimeter deep while the white parts should be zero millimeter deep – an exceptionally planned version of intaglio techniques used by engravers and printmakers for ages, with a few extra safety precautions. In the Fraser lab, users of the high-powered industrial laser stand outside an enclosure to observe the beam doing its work, entry to which would cause the machine to shut off automatically and immediately.

Yin had already manufactured the creative visual demonstration for a recent conference in San Francisco, but there she had ten times the time to explain how she did it. “It was mostly a process of taking out jargon,” as she describes the work of paring down from thirty minutes to three. That refinement was due in large part to a little help from her friends. Everyone’s presentation style is different and Yin found hers meant that she “needed to prepare exact words, or else [she] would tend to mumble or go into too much detail.” The biggest change she made from the heats to the Queen’s finals was to stop rocking back and forth as she spoke. “The camera really accentuated it,” she groans with good humour about her performance. And let that be a word of advice to future competitors: you may have to make a trade-off between self soothing and audience distracting.

Throughout her time at Queen’s another source of advice and support has been the mentorship of the recently late Dr. Geoffrey Lockwood, former Chair of the Engineering Physics program. “He influenced me a lot and he gave me so much help,” Yin explains. “When students switch into the Engineering Physics program they usually have to take an extra year to catch up on the necessary material,” but she says that “Dr. Lockwood kept encouraging me that I could do it in four years if I work hard, and I did.” Courses with Lockwood were also a source of inspiration, and Yin hoped to work with him in her graduate degree until he was diagnosed with brain cancer and sadly passed away this February. “He lived an incredible life and touched so many students with his teaching. He is deeply missed,” Yin adds. Looking back, she says with immense fondness, “my undergraduate education really changed who I am.” And the experience made her passionate about the research she is doing now, whose medical applications might one day make a difference in the prognosis of someone like Lockwood.

Yin herself also gives back for the sake of science and the students who love it. This year the torch is passed to her and her colleagues to represent Queen’s physics department at Kingston’s annual Science Rendezvous, where she will be delighting school kids (and their parents, no doubt) by using liquid nitrogen to make ice cream right before their eyes. (In case you’re wondering, you can pour liquid nitrogen directly onto the milk, sugar, and other good stuff, and they freeze because liquid nitrogen vaporizes rapidly at room temperature, taking away a lot of heat from the mixture). Yin also helps organize the condensed matter physics group weekly seminar series, which brings in scholars for a one-hour talk so that labs get a sense of what’s going on elsewhere and graduate students get a chance to network. Sometimes it even seeds collaborations.

Aside from all this, Yin is an avid basketball player, having played on Queen’s intramural women’s team for the past four years (“everyone I started with has graduated and gone!” she laments). This year she joined badminton, which she sees as a great way to get some physical activity without having to get a team together.

Fellow sports enthusiast and champion of all that is 3MT, the SGS’ Colette Steer will accompany Yin to the 3MT provincials. The story of her work and her slide will stay the same, but certain wording emphasis will change on the recommendation of Steer and Associate Dean Sandra Den Otter, who helped her analyze the playback of her winning performance. Looking ahead to the next competition, Yin remarks that 3MT has made her a lot more confident. The difference is merely having expressed the ideas out loud and seeing them met with nods rather than rotten tomatoes. “Now I know that people like it and they can get it.” With Steer as well as her best friend beside her for the next round, Yin is sure to have more than a few fans.

CAra receives her winning cheque from Principal Woolf and Vice Provost Brenda Brouwer 

Cara receives her winning cheque from Principal Woolf and Vice Provost & Dean, School of Graduate Studies, Dr Brenda Brouwer