Bathed in spotlights on the Reynolds Theater stage, Duke Dr. Jeffrey Lawson motioned to the big screen at a photo of a human arm peeled open in surgery, surrounded by gloved hands.

"This is what I do during my day job," Lawson said, pointing out that he was removing plaque build-up from a person's blood vessels.

Lawson was one of 12 speakers Saturday at TEDxDuke, the local spinoff of TED, in which speakers share "Ideas Worth Spreading" at live events worldwide and through online videos. TEDxDuke topics presented by students, alumni, faculty and community members ranged from the intersection of environmentalism and art to new technologies that help care for patients with breast or cervical cancers.

Lawson, a vascular surgeon and professor of surgery, took this year's TEDxDuke theme, "Challenge Accepted," and framed it with a story of his team's 15-year quest to create an off-the-shelf blood vessel that can be implanted into human patients.

The team of doctors, surgeons and researchers implanted the first bioengineered blood vessel, made from a biodegradable scaffold and smooth muscle cells provided by organ donors, into the first U.S. human patient last year at Duke Hospital. The breakthrough is currently undergoing clinical trials.

Lawson had a special message to audience members studying bioengineering: Take the work of his team and build on it.

"Grow a kidney, so you can alleviate the need for dialysis in the first place," Lawson said. "Or grow a heart, or lungs, for people with chronic pulmonary disease, who can't breathe anymore, who are suffocating. Grow them lungs. Or for those who are blind, grow them an eye. That's your challenge."

This year's event sold out, filling 572 seats in the Reynolds Theater, and was organized by an executive team of seven Duke students, who selected the event leadership, put together the program, and raised money and sponsorships. This is the fourth year of TEDx at Duke.

The TEDx talks also took the form of moral issues plaguing the U.S. Duke psychology professor and behavioral economist Dan Ariely asked the audience to consider what they believed to be the "right level" of national income equality.

If people take a risk and that risk pays off for them, society is less willing to take away their earnings and redistribute it, he said, adding, "You should get some of the value from the risk you take."

But what if people are brought up in an environment where they don't have the freedom to make such risky decisions? The bottom 40 percent of people in the U.S. (the poorest) only have .3 percent of the wealth, he said. The top 20 percent have 84.4 percent of the wealth.

"While inequality in the U.S. is really terrible and it's only getting worse, I think there is hope," Ariely said. "And the reason I think there is hope is because we do have this inherent dislike for inequality, because we don't understand it yet and we want something else."

During the event, Michael Faber, the program manager for Duke's creativity incubator, Innovation Co-Lab, hosted a table and shared information about Blue Sky, the lab's new online platform for sharing ideas to better the Duke community.

On Blue Sky before the event, people posted questions inspired by TEDxDuke, such as, "How can current Duke students learn from alumni?" and, "How can we learn faster, then share what we know?"

"The Co-Lab is just generally trying to grab onto some of those good ideas and turn them into real things," Faber said.

Even though the event was focused on challenges, many of the speakers shared how they overcame obstacles and discussed what they plan to accomplish in the future.

"The context is the challenge," said Faber, "but the message is the hope."