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Talkin’ Underwater Vision at the Student Research Symposium

Sierra Warren

Sierra Warren

San Diego State biochemistry major Sierra Warren was more or less born a fish. She’s been swimming since she was little. Here at SDSU, she played water polo and competed on the diving and swim teams. She moves effortlessly through the water and feels completely at home under the sea, so it always bothered her that whenever she visited the watery depths, she never could see very clearly.

The naked eye provides hopelessly blurry vision underwater, and goggles and diving masks are uncomfortable and frequently fog up. Warren thought there had to be a better solution to seeing underwater.

She sought out the expertise of University of Arizona optical scientist Jim Schwiegerling and dove into optics literature at that university’s College of Optical Science library. Slowly, Warren, Schwiegerling and a few other colleagues began working on a prototype contact lens that would give its wearer the underwater vision of a frog or fish.

Reading or swimming

Warren spent all day studying optics literature, all night testing out the prototype in a university pool. The design for the lens is fairly straightforward: A rigid contact lens is built with a little bubble protruding out the front. Inside this bubble, the researchers squirt a few drops of saline solution. Once the wearer—in this case, Warren herself—inserts the lens, the saline solution covers the eye’s pupil.

Underwater, the bubble full of saline solution refocuses light toward the cornea, counteracting the light’s refraction in the water. The result is near-perfect underwater vision.

Warren was one of 580 students presenting at last week’s SDSU Student Research Symposium, where she explained the lenses’ design and the experiments used to test them.

Vision quest

Colleagues assessed Warren’s vision with the contacts by conducting tests while she was submerged in the pool. They used three different charts: one with letters just like you’d see in an optometrist’s office; another with various shapes; and a third with hand signals.

Warren, who naturally possesses 20/16 vision above ground, had 20/20 vision wearing the contacts in both sunny and artificially illuminated conditions. At sunset with no artificial lighting, her vision clocked in at 20/63. That slight drop-off is to be expected in low-light conditions, Warren said, but it’s still pretty good.

The lenses are surprisingly comfortable, she added.

“At first, they’re a little tricky to put in, but once they’re in, I can barely feel them,” Warren said.

For those of us, like your Curious Aztec, blessed with less than perfect natural vision, the lenses will still work, Warren explained. By varying the shape and volume of the saline bubble on the front of the lens, researchers can make the lens work like a traditional corrective lens, bringing the wearer’s vision to around the 20/20 range.

“It doesn’t matter if you’re legally blind, we can make you see underwater,” Warren said.

Military use

Don’t expect these lenses to hit consumer shelves anytime soon, though. Because of the contact’s rigidity, there’s a danger that it could scratch the wearer’s cornea and invite infection. Instead, Warren and her colleagues think the lenses are more suited to military applications. Specifically, they’d like to see Navy SEAL divers use them to enhance vision during underwater missions.

But eventually, with enough testing and safety measures implemented, Warren’s lenses could become as commonplace as goggles among the general public.

“I love being underwater. It’s where I belong,” she said. “I want everyone to be able to experience the underwater world.”

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What’s up with the new student union’s green roof?

Q: What’s with the green roof on top of the new Aztec Student Union?

Green roof

Water drains from the rooftop garden into enormous tanks beneath the courtyard.

A: Green roofs are a recent eco-trend among builders looking to turn a building’s infrequently used space into an environmentally friendly feature. At 1,382 square feet, the new union’s green roof is smaller than some others out there (the largest green roof in North America, Ford Motor Company’s River Rouge production facility in Charlottesville, VA, clocks in at more than 450,000 square feet). But it makes the most of its small size, serving both a functional, environmentally-friendly purpose, as well as a demonstration of the possibilities that green roofs offer.

SDSU’s green roof—in essence, a rooftop garden—has a gorgeous panoramic view of campus and its surrounding hilly neighborhoods. It’s not open to the public, but eventually students, faculty, staff and other visitors will be able to attend events on the roof.

When Glen Brandenburg, SDSU’s director of facilities and sustainability, gave me a tour, it was a rare overcast, misty day in San Diego. Bad for the view, but good for the green roof’s plants, Brandenburg told me.

The plants in the garden are all succulents, able to survive on relatively little rainfall by absorbing moisture from air. The plants will survive just fine with only occasional watering.

The succulents came pre-planted in modular containers, giving the garden its squared-off, Tetris-like pattern you see in the photo. Over time, Brandenburg said, the plants will wander and the garden will take on a more natural appearance.

When it does rain, the roof drains the collected rainwater and filters and stores it in three 50,000 gallon tanks beneath the student union’s courtyard. That water is then used to water the plants around the union and provide water to the courtyard fountain. Based on average rainfall in San Diego, Brandenburg said the roof should be able to capture sine 300,000 gallons over the course of a year—more than enough to provide all the water needed for the new building’s landscaping.

By capturing and filtering this water, Brandenburg added, the roof also helps to prevent runoff from carrying pollutants to San Diego’s waterways.

Additionally, the garden helps to cool the building to cut down on air conditioning costs and electrical usage.

“The soil acts as a natural insulator,” Brandenburg said. “In the summer, it keeps the roof cool.”

But perhaps the green roof’s greatest environmental asset is its ability to inspire others to adopt similar technology, he said.

 “When you’re up there seeing the green roof, you can’t help thinking about the roof and asking questions,” Brandenburg said. “Our hope is that as people come up and see it, they’ll want to replicate the technology in their own buildings.”

Soon, solar panels will be added to other parts of the roof, further supporting the building’s sustainability.

Once everything is in place, the building as a whole should use about half as much energy as a comparable building without sustainability features, Brandenburg said.

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How Much Coffee Does America Drink?

Dear Curious Aztec,

How many pounds of coffee are consumed annually in the United States? —@jtjordon via Twitter

Latte art

CREDIT: Takeaway/Wikimedia Commons

Approximately 12 million pounds*.  But that’s not a terribly satisfying answer, is it? Let’s dig a little deeper into our country’s coffee habits.

One of the most frequently asked questions about coffee, says San Diego State associate professor of nutrition Mee Young Hong, is whether it’s bad for you. It turns out that’s a complicated question to answer.

The psychoactive substance that people crave in coffee is, of course, caffeine.

“We don’t know the maximum dosage of caffeine that can be considered healthy,” Hong told me, as I sipped a cup of coffee I’d brought to the interview. “We do know that studies have shown that having up to six cups a day doesn’t cause any death.”

Death? I sipped more cautiously. Hong’s statistic sounds a little scary, but what it really means is that studies have shown that drinking up to six cups of joe per day isn’t likely to increase your chances of dying. Or in other words, people who drink that much don’t appear to die any earlier or more frequently than their less coffee-addicted peers.

It’s exceedingly rare, but there are a few documented cases of people dying from caffeine overdose. However, their caffeine levels were found to be much, much higher than even the most diehard, just-hook-the-coffeepot-up-to-my-IV java junkie could consume via coffee alone. These cases typically consist of people ingesting an enormous number of caffeine pills. While your typical 8 oz. cup of coffee contains around 50mg of caffeine, caffeine pills can contain much higher dosages.  A 2005 case study out of the New Mexico Department of Health estimates that it would take about 5g of caffeine to kill an adult, or more than six gallons of coffee.

But what about other health concerns? Coffee does induce a number of physiological effects in the body, Hong said, including accelerated heart rate, increased blood pressure, and increased diuresis (that is, having to go).For people with certain heart conditions or who are dehydrated, drinking coffee might pose a danger.

A more indirect health concern isn’t the coffee itself, but what people put in it. Many people, especially younger folks, drink their coffee with lots of added cream and sugar—think iced caramel mocha cappuccinos and triple-venti frappes.  A cup of black coffee has a negligible number of calories, Hong said, but these sugary, creamy caffeine confections can contain upwards of 400 calories or more, essentially adding on a non-nutritious meal to the drinker’s daily diet. And that spells trouble for a nation already struggling with an obesity epidemic, Hong added.

But over the long term, coffee in and of itself hasn’t been found to pose any danger to healthy adults, Hong noted. Whew, I thought.

In fact, many lines of research point to coffee having several health benefits, Hong said. Most notably, moderate coffee intake has been linked with a reduction in your chances of contracting type 2 diabetes. Coffee is also an antioxidant, which some studies show could reduce the risk of cancer and other diseases, although Hong cautions that pouring non-dairy creamer into your drink can cancel out this benefit.

“If you’re a coffee drinker, then enjoy it in moderation,” she said.

As for Hong herself, she’s partial to green tea. To each her own.


*My math is as follows: Reliable coffee-drinking data is available only for people ages 18 and over, of whom there are about 236 million in the United States. Now, recent data from the National Coffee Association suggests that 54 percent of American adults are regular coffee drinkers, and their average comes out to around three 8 oz. cups per day. American adults therefore drink about 382 million cups of coffee every day. A 1-lb. bag of coffee will make approximately 32 cups, so we can roughly estimate that over a given year, Americans will consume 11,947,500 pounds of coffee. Your Curious Aztec has contributed more than his fair share.

Do you have a question for The Curious Aztec? E-mail him, leave him a tweet @TheCuriousAztec, or leave a message on SDSU’s Facebook page. You stay curious, San Diego State.

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Will Technology Ever Stop Advancing?

Dear Curious Aztec,

Will there be a point in time where technology will NOT be able to get faster or continue advancing? —@grapeee_SODA viz Twitter

Wow, first question this column has tackled, and it’s a doozy. Strap in, because before we’re done we’ll be exploring the edges of space and time. But first, let’s get our terminology straight. “Technology” has a few definitions, but let’s work with this one: Technology is anything built or configured using information to achieve some practical purpose. Information—any information—can be encoded as a series of 1s and 0s, with each binary digit called a bit.

Got it? OK.


Sculptor Michael Salter’s Big Styrobot with Little Buddy.

Over the years, a number of mathematicians and information theorists have set out to quantify the relationship between technological progress and our ability to compute information. The most famous of these is probably Moore’s law, named after Intel honcho Gordon E. Moore, which states that the number of transistors per microchip doubles approximately every two years.

It’s not really a law in the way physicists and mathematicians use that word, but it’s held pretty well true over the past several decades. It accurately predicted that processing speed, memory capacity, and a handful of other useful markers of technological progress would grow exponentially between the 1960s and today.

But will Moore’s law always hold true? I called Vernor Vinge, San Diego State Emeritus Professor of computer science and Hugo Award–winning science fiction author to ask him. He said that even though we’ve frequently encountered apparent bottlenecks in the progress of technology, we’ve found ways around them.

“There’s a theoretical limit to the number of bits per second you can transmit over, say, a phone line, and it’s a very well thought-out and strict limit,” Vinge said. “We’ve far exceeded that, but we didn’t exceed it by breaking the laws of physics. We did it by changing the characteristics of the communication channel.”

In other words, what humans have always excelled at is finding ways around technological limitations by building new technology.

“So my short answer is: In the absence of physical disaster, I suspect that technological progress will continue for some time,” Vinge said.

So far, so good. But then he went on: “After that, it might be impractical for us mere humans to assess the nature of future progress.”


Sculptor Michael Salter stands before his spongy overlord, Giant Styrobot, at the San Jose Museum of Art in 2008.

That sounds ominous. Vinge, it turns out, is one of the founding fathers of an idea known as the technological singularity. It sounds like something straight out of science fiction—and indeed, Vinge has written several books about it—but he and other futurologists believe that sometime in the not-too-distant future, humans will create an artificial intelligence that surpasses human intelligence. After that, pretty much all bets are off and all predictions are moot, as human beings won’t be able to comprehend the designs and maneuverings of that superintelligence.

“The analogy I like to use is that it would be like us explaining our technology and society to a goldfish,” Vinge said.

Glub glub.

While that is an unsettling notion to some, including your Curious Aztec, know that this is a highly controversial suggestion. Experts from fields ranging from computer science to neuropsychology disagree vehemently on when, or even if, a technological singularity could occur. Many scientists think it’s pretty far out there, but then again, a number of them take it seriously.

But putting aside arguments over the singularity, either we or superintelligent computers or some other intelligence out there in the galaxy likely will continue to create and innovate and build new technology well into the future. How long can any of us keep it up?

Let’s go back to the idea that technology is essentially applied 1s and 0s. Well, the properties of subatomic particles can also be described in 1s and 0s. Based on estimates of the age and temperature of the universe and the relationship between matter and energy, a number of physicists have worked out theoretical upper limits to the information content of the universe. The universe, they say, contains between 1090 and 10120 bits. No one can tell you when we (or someone or something else) will hit that upper boundary, but it’s going to happen eventually, quadrillions of years in the future.

Unless, as Vinge points out, a speculation by theoretical physicist and polymath Freeman Dyson comes to pass: “Perhaps one of the late-term projects of our ultimate descendants will be engineering the immortality of the universe,” Vinge explained.

If that happens, then the answer to your question is no. Otherwise, yes—when either supercomputers take over or we literally run out of information in the universe. Told you it was a doozy.

Do you have a question for The Curious Aztec? E-mail him at, leave him a tweet @TheCuriousAztec, or leave a message on SDSU’s Facebook page. You stay curious, San Diego State.

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Welcome to The Curious Aztec!

Welcome to The Curious Aztec, San Diego State University’s weekly science-and-research Q&A column! Here, students, alumni, San Diegans, and humans of all stripes pose questions to SDSU’s science and research writer, who will then take those queries to the university’s big thinkers. Will it be rambling and ponderous? You bet! Will your Curious Aztec risk life and limb to plumb the depths of mortal knowledge? Absolutely! Will your question actually be answered? The point is, we’re having fun!

If there’s some mystery of the universe roiling about your gray matter, tweet it to @thecuriousaztec or e-mail Thanks for reading!

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