Johns Hopkins Magazine -- September 1999
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"Thank God It's Launch Day..."
Immersed in bubble math
A major payoff
Wowing the RNA Club
Listening like a sub
Alumna's earthy pursuits rewarded

The view from the Bloomberg Center's mission control room.
Photo by
Jay Van Rennselaer
"Thank God It's Launch Day..."

An air of celebration, tinged with anxious excitement, filled Physics and Astronomy's Schafler Auditorium in the minutes leading up to the launch of the Hopkins-built FUSE satellite on June 24. An overflow crowd of faculty, students, local children--including at least one Girl Scout troop--turned out to watch a live video of the scheduled 11:39 a.m. takeoff, emceed by FUSE research scientist Bill Blair.

The genial Blair gave an overview of the mission and took questions from the audience. When one little boy inquired, "What would happen if by accident FUSE flew into a Black Hole?" Blair paused a beat and then said solemnly, "I would be very sad." The scientist even belted forth a stirring original rendition of "Thank God It's Launch Day," to the tune of Frank Sinatra's "I Did It My Way."

Downstairs in the Bloomberg Center's mission control room, there were no loud cheers when the Delta II rocket began its ascent into space. The computer experts there quietly watched the takeoff and then prepared for their real work to begin an hour later. That's when NASA handed over control of the spacecraft to the Hopkins FUSE team. It was momentous stuff--the first time that a large-scale space mission would be controlled and operated by a university.

Planning and assembly of the Far Ultraviolet Spectroscopic Explorer satellite began a decade ago, and over the years have involved the work of 600 people at NASA, Hopkins, Hopkins's Applied Physics Laboratory, the Canadian and French space agencies, and a variety of space science firms and universities.

Photo courtesy
Hopkins's Warren Moos is the mission's principal investigator; he and several other key team members, including project manager Dennis McCarthy, research scientist Ken Sembach, and NASA's George Sonneborn, were in Cape Canaveral, Florida, for the launch--a celebratory affair that drew dozens of Hopkins scientists and their families.

FUSE is a satellite with a relatively small pricetag ($120 million) that is expected to offer answers to some of our biggest questions regarding the origins of the universe: What were conditions like in the first few minutes after the Big Bang? How do galaxies evolve? Will a fossil remnant of the birth of the universe ultimately bear out the Big Bang theory--or subvert it?

FUSE will complement other NASA missions, such as the Hubble Space Telescope, by detecting far-ultraviolet wavelengths that are invisible to other telescopes, including Hubble. In particular, FUSE will sample a fossil nucleus of an isotope called deuterium, which was created, says Moos, "three minutes after the Big Bang." During FUSE's expected three-year mission, scientists will sample measures of deuterium in a variety of places, from the inner recesses of our solar system to the outer reaches of the Milky Way. Those measurements should provide the information they need to peer back into time and figure out what conditions were like just after the Big Bang. Since star formation is thought to depend on the regular destruction of deuterium, a deuterium map of the Milky Way galaxy should also provide a better understanding of how chemicals are mixed, distributed, and destroyed--both in our galaxy and others.

In July, FUSE successfully found and tracked its first star image, part of initial calibration testing using software developed at APL. To keep pace with FUSE's findings over the next several years, stay tuned to Johns Hopkins Magazine. --Sue De Pasquale

Immersed in bubble math

In 900 B.C., Queen Dido of Carthage stands on the sandy banks of the Mediterranean Sea and studies the land before her. A local king has accorded Dido as much of the region as she can enclose with an ox's hide. Dido, of course, wants to maximize her claim. So she instructs her workers to cut the hide into thin strips, tie the strips together, and use the rawhide cord to mark her territory. But what shape should they enclose?

Dido's task, which Virgil described in his epic poem, the Aeneid, is actually a fundamental mathematical problem. The Greeks called it the isoperimetric (equal perimeters) problem: with a perimeter of given length, what shape has the maximum area?

The answer is a circle, and Dido's solution shows that the queen obviously knew her geometry.

Millennia later, Hopkins mathematician Joel Spruck is still pondering the isoperimetric problem and related equation called the "isoperimetric inequality." But while Dido's task involved two dimensions, Spruck is delving into higher dimensions of Euclidean space and even non-Euclidean space.

Photo courtesy
David Draper
Spruck has studied the isoperimetric problem for two years, always while juggling other research and teaching responsibilities.

Now, thanks to the Guggenheim Foundation, he'll spend the next year in Paris, a mathematician's mecca, focusing on the problem. Spruck is among 179 scholars nationwide who were awarded Guggenheim fellowships last spring.

His starting material is the bubble.

"A bubble," Spruck remarks, "has a beautiful geometric description."

When a child blows through a bubble wand that has been dipped into a soap solution, a fixed volume of air is enclosed by the film. What shape emerges? Not a pyramid. Not a cube. Only a sphere. That is because a sphere has less surface area (and thus, surface tension) than any other enclosed three-dimensional shape. (While some bubbles stretch into wobbly hourglass or hot dog shapes, the only stable bubble is spherical, Spruck notes.) It follows, then, that the shape with a given surface area and the largest volume is a sphere. This is the three-dimensional version of Queen Dido's puzzle.

Spruck's problem solving also involves non-Euclidean structures called Riemannian manifolds. The curvature of Euclidean space is zero (in other words, it is flat), while a sphere has constant positive curvature. The manifolds, however, have curvatures that change from point to point, and can be negatively curved.

"It's conjectured that the Euclidean isoperimetric inequality should still hold, or be better" for negatively curved manifolds, says Spruck. However, even though the geometrical principle should be the same, a "bubble" in Riemannian space would look altogether different from a conventional bubble. Spruck is developing new analytic and geometric techniques to demonstrate this conjecture.

Bubble math, though seemingly esoteric, could have practical applications, Spruck notes. The mathematics involved in the mean curvature (or average bending) of a bubble's surface, he says, "is related to the theory of phase transitions, materials science, problems of melting and cooling, and biological models." (The distance a liquid will flow through a tube, or blood through a capillary, is related to the curvature of the meniscus at the top of the volume of liquid.)

Spruck is looking forward to spending most of his time immersed in bubble theory, he says, perhaps taking a breather now and then to work on writing a math book. "Doing abstract mathematics," he admits, "is the kind of thing where you have to do something else to keep your feet on the ground or you start to lose it." --Melissa Hendricks

Illustration by
Kevin O'Malley
A major payoff

Hopkins computer science students who graduated last spring will have a real jump on paying off their student loans: annual salaries as high as $65,000.

At Homewood, the 50 or so seniors who majored in computer engineering or computer science are commanding the highest salaries in the undergraduate class of 1999. The fresh-out-of-school range is now $39,000 to $65,000, with more of the offers shifting toward the high end, according to administrators. --Joanne P. Cavanaugh

Wowing the RNA Club

Every month, a group of researchers in the Baltimore-Washington area attends a meeting of a club so exclusive that the ticket for membership is in-depth knowledge of ribonucleic acid, or RNA.

RNA is a key cellular molecule. When bound to special proteins, it forms the heart of the ribosome, the cellular machine that produces all proteins. Scientists have worked for decades to understand the structure and function of these fundamental units.

At an "RNA Club" meeting this past spring, Hopkins chemist David Draper unveiled a hot-off-the-press structure of a large, important section of an RNA/protein complex from the ribosome. This was an audience that would know an amazing RNA structure when they saw one. And the group was wowed.

In this detailed view of part of a ribosome, RNA (left) binds to a protein (green).
"Cool!" "Amazing." "That's something!" echoed through the room as brightly colored images of the structure were projected on a viewing screen.

No specialist in the RNA world had ever seen such a large section of RNA depicted in such complex three-dimensional detail.

Scientists learned the detailed topography of DNA's double helix decades ago. It's taken much longer to characterize RNA, which has an infinitely more variable structure. Further, the ribosome, which contains RNA, is an enormous molecule. Determining its structure has been a little like trying to use a magnifying glass to understand how a mansion was built.

Draper's RNA structure gives scientists their first peek. He and Hopkins biophysicist Eaton Lattman and their colleagues reported their finding in the May 14 Science.

Instead of examining the entire ribosome, Draper carefully selected a chunk in which a major part of protein synthesis occurs.

Determining its structure was still a difficult feat. While Draper and other RNA scientists were familiar with the hairpin turns and junctions that affect RNA folding, they now saw that this RNA twisted itself into more conformations than they had ever realized.

So postdoctoral researchers Graeme Conn and research assistant Apostolos Gittis worked on the structure piece by piece, manually building short stretches of the RNA sequence with computer modeling programs.

Though the team's final structure represents only about 1 percent of the entire ribosome, Draper says, "it represents a stepping stone in understanding the entire ribosome." --Resi Gerstner is a doctoral candidate in David Draper's laboratory.

Listening like a sub

What do a submarine and a human fetus have in common? First off, you might say, they both function in water.

Now there's another answer. Hopkins's Applied Physics Laboratory has adapted decades-old U.S. Navy tactical technology to track the heartbeats of babies in the womb.

Under a patent pending this year, Hopkins doctors and APL physicists have developed and tested a fetal heart monitor that can gather electronic signals from the heart using an array of sensors attached to the mother's belly. The method, more accurate and easier to use than current technology, could provide a great deal more information on how the fetal heart works.

As it is now, doctors can check a baby's heart rate by using ultrasound or an electrocardiogram (EKG), which requires an electrode to be attached to the fetal scalp. The first doesn't offer a refined measure of heart activity. "It's like trying to draw a fine sketch with a thick Magic Marker," says APL's John Cristion. And when the baby moves, the heartbeat is lost. The fetal scalp method is an invasive procedure that requires the baby's delivery within 24 hours.

In 1992, the School of Medicine's Robert Greenberg visited APL during a conference, telling scientists there that doctors were looking for a more accurate way to monitor fetal heart rates.

Cristion, Ed Moses, and Wayne Sternberger, of APL's Strategic Systems Department, called upon their knowledge of military sensor design and detection systems to come up with a non-invasive method for providing EKG data.

The underwater-born idea behind the new fetal EKG (later created with Greenberg and Eva Pressman, former assistant professor in obstetrics) is called adaptive signal processing. "Submarines in the ocean tow behind them long arrays of sensors, like microphones, called hydrophones. Basically, they are listening out there in the water," says Cristion.

The submarines identify a particular ship by taking information from dozens to hundreds of sensors to draw a picture of the whole. The process can tune out some sounds, just as the human ear can filter out background noise to focus on a conversation at a dinner party.

That's crucial for detecting a fetal heart rate, a minuscule signal that can get lost in the cacophony of electronic signals produced by mom. "A fetal heart's electrical signal has to propagate through the fetus, the uterus and abdomen of the mom," says Sternberger.

The new method, predict the researchers, will enable a laboring mother to walk around with strips of electronic sensors attached to her skin, constantly monitoring her baby's heart. This would be especially useful during high-risk pregnancies. "You can get a fetal heart wave form with much finer details," Cristion says. This would alert doctors immediately if the "fetus has had distress." --JPC

Alumna's earthy pursuits rewarded

Creativity, according to the MacArthur Foundation, involves "connecting the seemingly unconnected in ways that are significant." The foundation handsomely rewards such creative promise through its fellowship program.

Thus, it should come as no surprise that Jillian Banfield (PhD '90) received one of the 31 coveted five-year fellowships the foundation awarded this June. An associate professor of geology and geophysics at the University of Wisconsin, Madison, Banfield is exploring, among other things, the connections between the seemingly disconnected realms of minerals and microbes. This new interdisciplinary field is called geomicrobiology, and Banfield is one of its pioneers.

Banfield studies unusual microorganisms called extremophiles, so-called because they live at the environmental fringes--in the case of one of her research projects 350 feet underground, beneath an abandoned iron mine in northern California. Conditions in the mine are extremely acidic and hot, and the rock is loaded with arsenic and iron. It's the ideal home for one group of extremophiles that derives its energy by oxidizing iron.

Banfield is analyzing the conditions in the iron mine that make it the perfect habitat for the iron-dependent microbes, and studying how the microbes affect the breakdown of the rock. "We want to understand the microecology," she says. Such research could one day yield practical applications, for example, in improving the cleanup of abandoned mines.

Banfield is also researching how weathering and other physical processes contribute to the formation of soils and sediments, and is investigating how toxic heavy metals build up in the earth.

Like the feisty microbes she studies, the Australian-born Banfield has a reputation for intensity. "She works at a pace that astounds people," says her former Hopkins mentor, David Veblen, Blaustein Professor and chair of Earth and Planetary Sciences. --MH