Johns Hopkins Magazine -- February 1998
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Student engineers get creative... survival of the toothiest... what we can learn from musclemen... an invading galaxy... a boost for APL

Thanks to the ingenuity of Hopkins Engineering students, George Rickels can continue carpentry as a hobby.
Photo by Steve Spartana
Engineering solutions for the disabled
In 1994, Baltimore resident George Rickels lost his forearms in a construction accident. Today, Johns Hopkins students have given him the means to work again.

Through an innovative program, students at the School of Engineering are focusing their senior design projects on developing tools that help disabled people use computers, drive cars, do carpentry, and perform other tasks that may have been shut off from them.

Take Rickels, a longshoreman who was injured in a forklift accident. He wanted to continue carpentry as a hobby. Three Hopkins students last year helped design a device that allows him to attach power tools--hand saws and drills--to the ends of his prosthetic arms without help, and then to use hook-cables to operate the tools.

"Our job was to make him totally independent," says Andrew Conn '57 (MS '59, PhD '64), a Hopkins senior lecturer in mechanical engineering who advises the student design teams. "The key is brainstorming, to take [students] back to a creative place in their lives where they were free and unfettered. We totally rule out the negative."

"I can do just about anything I want," says Rickels, 60, as he demonstrated the tools and adaptive devices one afternoon by sawing a board in half. "Ain't that neat? I've offered to be chief surgeon at Hopkins. I got a saw, I can go `bzzzzzzt.'"

For seven years, Hopkins students have worked with engineers from the nonprofit Volunteers for Medical Engineering (VME), a Baltimore-based group of engineers who work on disabled-access problems. Student engineers are told to work within a $6,000 to $7,500 budget. The Biomedical Engineering Department funds the VME projects, while groups ranging from the Baltimore Gas & Electric Company to the U.S. Navy pick up the tab on others.

Student projects done with VME include a curved keyboard that allows a quadriplegic person to use a mouth-operated breath stick to type, and a less-painful internal bone lengthening device.

"Students lack the background, but they have a good knowledge of certain engineering principles," says John Staehlin, a former longtime Westinghouse engineer and president and founder of VME. "They are very creative and pretty much uninhibited. I like that."

This year's student VME project is a device that will allow disabled drivers to refuel their vehicle from the driver's seat through an automated fueling system. At a brainstorming session in the fall, students bounced ideas around, drawing varied shapes for nozzles and caps. About a dozen classmates shot out suggestions to the three-person project team redesigning the cap-nozzle system.

"What do planes do when they refuel in flight?" one student asked, sparking a discussion about midair refueling.

"It's okay to steal ideas," Conn told the students. "Think of ideas you've seen before, if you saw them on Star Wars or whatever." --JPC

A Charles R. Knight rendering of forest horses from the Miocene period.
Photo courtesy Dept. of Library Services, American Museum of Natural History, Neg. #35818,
Photo: A.E. Anderson
A tale of horses, grass, and climate change
Millions of years ago, many unusual beasts roamed through North America. There were giant ground sloths, enormous lions, oversized beavers, and three-toed horses, says Hopkins paleobiologist
Steven Stanley.

Over time, species evolved or perished, for reasons that scientists can sometimes only surmise. One evolutionary conundrum has long puzzled scientists: Why did the number of horse species dwindle drastically six million years ago, from about 11 to only about four species. Whatever calamitous event caused the extinctions, it spared only the horse species with the very longest teeth.

Stanley: equine calamity
Stanley believes he knows what happened. He has developed a reputation for thought experiments that unite seemingly unrelated phenomena. For example, in previous research, he connected the Ice Age and a reduction of trees to an increase in human brain size. His current theory, which he described in October at the annual meeting of the Geological Society of America, once again links seemingly unrelated phenomena.

Stanley began to ponder The Mystery of the Long-Toothed Horses about a year ago. He started with the following facts. About six million years ago:

  • The Earth's climate became cooler and drier.

  • Grasslands expanded and forests declined.

  • The grass profile changed. Grass species known as C4 grasses began to replace C3 grasses, and to become the predominant type of grass in many parts of North America. C3 and C4 plants use different types of photosynthesis. C3 plants include many of today's lawn grasses such as Kentucky blue grass, as well as wheat and rye. C4 plants include Bermuda grass and corn.

  • Long-toothed horses expired. Very long-toothed horses survived.

    Can you connect the dots?

    Until recently, scientists believed that the shift from forests to grasslands somehow led to the extinction of the horses with shorter teeth. Scientists hypothesized that a reduction in carbon dioxide favored C4 grasses. But that did not completely answer the question of what caused the animals' extinction, says Stanley.

    To Stanley, the data suggested that a change in the horses' diet was causing their teeth to wear down faster. Whatever the change was, it apparently did not harm the horses with very long teeth, who had enamel to spare, but it wore down the teeth of the horses with only long teeth. These horses apparently did not get the nutrition they needed, says Stanley. Perhaps they became malnourished and weakened, more prone to predators or disease.

    So Stanley asked himself, "What is it about grasses that grinds down teeth?" He found the answer: silicates--the gritty compounds that are also found in sand and used to make glass. Plants use silica compounds as protection against predators. Perhaps, Stanley hypothesized, C4 plants have more silicates than C3 plants. "I thought it was a long shot," says Stanley.

    But he turned out to be right. On average, C4 plants have about three times as much silica as C3 plants. And C4 grasses prefer drier conditions. So from extra silica to horse extinction, there is the connection, says Stanley.

    "People think a lightbulb just goes off, but it's always logic," he says, in explaining how he does his science. "It was a hypothesis. I tested it just by looking at the literature. It's almost a deterministic thing."

    Horses are not the only mammals who may have been affected by this transition, says Stanley. Other grazing mammals including rhinoceri and camels also became extinct around the same time, perhaps for the same reason.

    By approximately 11,000 years ago, all horses in North America had died or been killed by human hunters, notes Stanley, but not before several horse species had spread to Europe by crossing the Bering land bridge that once connected Alaska and Siberia. Spanish conquistadors then reintroduced horses into the New World. --MH

  • Hefty rump roasts: a Belgian Blue
    Photo courtesy Dee Garrels, Chet Pennington/ Proceedings of the National Academy of Sciences, Vol. 94, Nov. 1997, Copyright (1997) National Academy of Sciences, USA

    Here's the beef

    Se-Jin Lee, a Hopkins molecular biologist and self-described runt, is reading Muscle & Fitness and MuscleMag these days. Not for his personal biceptic enhancement. Lee is searching for the Hulk Hogans and Arnold Schwarzeneggers of the world whose brawn might stem from a mutation in a gene called myostatin.

    The myostatin protein, explains Lee, is found in skeletal muscle (which is used for voluntary movements), where it appears to tell muscles when to stop growing. Last May, Lee and his colleagues reported that they had "knocked out" the myostatin gene in mice, creating a strain of mighty mice whose muscles are two to three times larger than normal (Johns Hopkins Magazine, June 1997).

    Now, Lee and postdoc Alexandra McPherron find that nature has done some tinkering of its own with the myostatin gene. Mutations in the myostatin gene apparently account for the "double muscling" in two especially beefy strains of cattle--Belgian Blue and Piedmontese. The mutations in the cattle arose spontaneously, perhaps hundreds of years ago, and were carried down through the generations, says Lee, who reports the results in the November Proceedings of the National Academy of Sciences.

    The findings could help agricultural researchers develop meatier strains of chickens and pigs, notes Lee.

    But Lee's present goal is to find out if any people have myostatin mutations. If he finds such spontaneously occurring mutations, they could suggest how he might disarm the gene in people who need extra muscle. There might be a way to deactivate myostatin through drugs, for example. "The primary targets would be people with muscle degenerative diseases such as muscular dystrophy or muscle wasting (generally referred to as cachexia) due to cancer, AIDS, or other chronic diseases," he says.

    So Lee convinced bodybuilding journalists, including MuscleMag's "Johnny Fitness," to help. In recent issues, they explain Lee's research and seek volunteers who will donate a vial of blood, which Lee will screen for myostatin mutations. Since the articles have appeared, says Lee, "we've been barraged with calls." --MH

    A parasite of galactic proportions
    We're being invaded.

    A tiny galaxy called Sagittarius is penetrating the Milky Way. But don't worry. There is no need to run for cover. The invasion began billions of years ago and continues far from Earth on the other side of the center of our galaxy, says Rosemary Wyse, with a chuckle.

    But having another galaxy plonk in the middle of our own provides a unique opportunity for astronomers, says Wyse. One current theory holds that smaller galaxies like Sagittarius merge to form larger galaxies like the Milky Way. "What's not clear is what sorts of small systems? What was the merging rate? And is it still ongoing?" says Wyse, a professor of astronomy at Hopkins and world expert on galaxy formation and evolution, who is studying Sagittarius with a variety of instruments. "The merging history of galaxies could determine how they look today."

    What she and her colleagues have learned about Sagittarius indicates that the answers are not simple.

    Although Sagittarius has been part of the Milky Way for much of the larger galaxy's existence, astronomers only discovered it a few years ago. Roddy Ibata, now at the European Southern Observatory, outside Munich; Gerard Gilmore, of the Institute of Astronomy, in England; and Mike Irwin, of the Royal Greenwich Observatory reported their finding in Nature in 1994.

    Lying in the line of sight of its namesake constellation, Sagittarius belongs to a class of small galaxies called spheroidal dwarf galaxies. It is less than 100 times smaller than the Milky Way.

    Sagittarius is probably losing stars to the Milky Way, says Wyse. "If a little galaxy gets too close to a big galaxy, the gravity of the big galaxy may overcome the internal gravity of the little galaxy, and so pull stars away." The gravitational tug of the Milky Way is elongating Sagittarius.

    Eventually, a little galaxy will shrink to nothing. But using telescopes in Australia and Chile, Wyse, along with the galaxy's discoverers, calculated that the stars in Sagittarius are approximately 10 billion years old, and that the dwarf galaxy has orbited the Milky Way about 10 to 12 times, which is a lot in galaxy terms.

    For Sagittarius to survive for that long, it must be losing relatively few stars and thus be "a fairly robust system," concludes Wyse, who is scheduled to discuss galaxy interactions, at the annual meeting of the American Association for the Advancement of Science, to be held this month in Philadelphia.

    What makes Sagittarius so feisty? The galaxy appears to contain a lot of dark matter, says Wyse, perhaps 10 times as much as a galaxy with the equivalent number of stars. The dark matter may also be an especially dense type--called baryonic dark matter-- that astronomers have not confirmed exists in the Milky Way, says Wyse. To learn more, she is using the Hubble Space Telescope to study the next closest dwarf galaxy, Ursa Minor.

    Sagittarius is the first galaxy found within the disk of the Milky Way. Other dwarf galaxies may be concealed by the Milky Way's stars. Wyse plans to hunt for those galaxies through a new project called the Sloan Digital Sky Survey. Starting next year, Sloan scientists will create a catalog of more than 200 million celestial objects.

    Sagittarius is one galactic invader, says Wyse. "The question now is, Are there others?" --MH

    A boost for APL
    Given the current uncertainty surrounding U.S. military spending, leaders at Hopkins's
    Applied Physics Laboratory were more than a little relieved last fall to sign a five-year, $1.6 billion contract with the Naval Sea Systems Command (NAVSEA). The Navy contract represents approximately 60 percent of the lab's annual budget.

    The Navy has been APL's primary sponsor since the Lab's founding in 1942. While the new contract is funded under the same level as previous Navy contracts, it shifts management authority from the Space and Naval Warfare Systems Command to NAVSEA. It will cover work in such areas as submarine survivability, theater air defense, weapon system evaluation, and battle space management. APL also signed a five-year $500 million contract with NASA, which represents about 17 percent of the Lab's budget.

    Written by Joanne P. Cavanaugh and Melissa Hendricks