UC Santa Cruz Tip Sheet February 1997
Research news and feature ideas, issued periodically by the UCSC Public Information Office
For more information, contact Robert Irion at (408) 459-2495 or irion@ua.ucsc.edu
Astronomy I Keck Telescope spies the likely building blocks of modern galaxies
Acting as the world's most powerful telescopic tandem, the Hubble Space Telescope and the W. M. Keck Telescope are starting to unravel the evolutionary histories of galaxies dating to when the universe was just 10 percent of its current age.
A year ago, Hubble's most penetrating view into the cosmos-- the Hubble Deep Field--gave researchers a bonanza of opportunities to explore how galaxies in the preadolescent universe matured into today's hulking goliaths, including our Milky Way. Now, UCSC astronomers have used the Keck I Telescope to analyze 24 of those faint blobby galaxies in detail. Their most noteworthy conclusions include the following:
* So many distant objects freckle the Hubble Deep Field that they probably could not all have grown uniformly into future massive galaxies. Rather, the variety of shapes and sizes suggests that many of them merged, to evolve later into the smaller number of "grand design" galaxies we now see.
* The distant galaxies were at least as luminous as the Milky Way but were about one-tenth as large. They created new stars at rates comparable to the pace of starbirth today, but they were much less prolific than galaxies that unleashed tremendous bursts of fresh stars billions of years later.
Postdoctoral researcher James Lowenthal, lead author of the study, presented his team's results on January 16 at a meeting of the American Astronomical Society in Toronto.
Contact: James Lowenthal--(408) 459-5722 or james@ucolick.org
Astronomy II Keck Telescopes find galaxies of normal stars surrounding quasars
Many quasars, the most luminous objects in the universe, are swaddled by galaxies containing ordinary stars that lie at the same distances from earth as the quasars themselves, according to a new study that used the Keck I and Keck II Telescopes in Hawaii.
The observations also provide tantalizing evidence that galaxy collisions fuel the prodigious energy outputs of at least some quasars, presumably by hurling fresh stellar debris into the gorges of gigantic black holes at the cores of the galaxies.
UCSC astronomers took the first detailed spectra of the nebulous blobs that lurk faintly around most quasars found to date. The spectra, which reveal the compositions and distances of light-emitting objects, clearly point to galaxies full of normal stars around the quasars. Features in the spectra indicate that the stars are mature, with ages of at least 1 billion to perhaps 10 billion years.
"The evidence is extraordinarily strong that quasars live in host galaxies, just as we expected," says astronomer Joseph Miller, leader of the observing team. "This is consistent with the hypothesis that quasars are natural features of massive galaxies. They are direct consequences of how galaxies evolve, not strange aberrations or freaks of nature." Miller presented his research on January 13 at a meeting of the American Astronomical Society in Toronto.
Contact: Joseph Miller--(408) 459-2991 or miller@ucolick.org
Seismology Monitoring compliance with the Test Ban Treaty raises challenges
Seismologist Thorne Lay of UCSC envisions his two-year-old son growing up in a world with no more nuclear explosions. If scientists can devise reliable ways to monitor compliance with the new Comprehensive Test Ban Treaty, Lay's vision very well may come to pass.
Researchers gathered in San Francisco on December 15 at a meeting of the American Geophysical Union to take stock of the extraordinary scientific challenges posed by the treaty. Speakers at a session cochaired by Lay explored the progress to date toward meeting the treaty's rigorous verification demands and the research issues that scientists still must address.
Although the treaty will not go into force for at least two years, it requires that a verification regime be put into place in the interim. The clearinghouse for data from the verification networks will be the International Data Centre in Vienna. When the centre is fully operational, up to 10 gigabytes of scientific data--equivalent to 10,000 floppy disks--will stream there every day.
The CTBT's verification regime covers four types of data: seismic, infrasound (atmospheric sound waves), hydroacoustic, and radionuclear (radioactive particles and gases). The international sharing of such a wide range of data, some of it potentially incriminating, is unprecedented in the arms-control arena and perhaps in all of science. The only comparable area, Lay notes, is the free exchange of data on atmospheric weather patterns.
Contact: Thorne Lay--(408) 459-3164 or thorne@rupture.ucsc.edu
Biochemistry Unveiling the molecular dance of an antibiotic and a bacterium
Scientists have exposed for the first time the precise interactions between a common class of antibiotics and the vital machinery in bacteria that they disable, setting the stage for targeted efforts by researchers to design new and more effective drugs.
A team led by UCSC biochemist Joseph Puglisi worked for more than two years to solve the puzzle of how the antibiotics grab a bacterium's ribosomes--the factories in every cell that make the proteins an organism needs to survive. The answer, mapped out atom by painstaking atom, sheds light on how the ribosome itself works, why the antibiotics kill bacteria but not people, and how some bacteria manage an end run around the drugs by developing resistance to their crippling tactics.
"Puglisi can see precisely how the antibiotic binds to the ribosome at the atomic level," says Harry Noller, director of UCSC's Center for the Molecular Biology of RNA. "This explains for the first time how a ribosome-directed antibiotic works. Since these are among the most widely used antimicrobial drugs, Puglisi's result is of major medical and scientific significance."
Postdoctoral researcher Dominique Fourmy of Puglisi's laboratory is first author of the report, which appeared in the November 22 issue of the journal Science.
Contact: Joseph Puglisi--(408) 459-3961 or puglisi@chemistry.ucsc.edu
Hydrogeology Fluids flow fleetly under the seafloor
Hydrogeologists have taken the closest look yet at the intricate cycle of fluids that flow relentlessly beneath the seafloor. That flow, it now appears, is far more forceful than expected.
Driven by the heat of the planet's interior, water courses through pores and cracks under the ocean in earth's upper crust. The water leaches minerals as it flows, altering the crust and suffusing the ocean with important elements. During Leg 168 of the Ocean Drilling Program, a two-month cruise last summer off the Pacific Northwest, researchers drilled as far as 1,900 feet into the seafloor on the flanks of the Juan de Fuca Ridge, where the planet churns out fresh slabs of oceanic crust.
The researchers collected the first known samples of pristine "basement" water--fluids trapped under the seafloor for many thousands of years. Chemical analysis of these and other samples points to a surprisingly energetic cycling of fluids and heat beneath the sediments that shroud the young crust.
"There's no question the water is moving much faster than we thought," says hydrogeologist Andrew Fisher of UCSC, cochief scientist on the cruise. The time it takes for the entire volume of the world's oceans to cycle through these subseafloor systems, he notes, could be "much, much shorter" than the previous estimate of one to two million years.
Contact: Andrew Fisher--(408) 459-5598 or afisher@earthsci.ucsc.edu
Geophysics Roots of "hot spots" may extend to earth's core-mantle boundary
"Hot spots," the isolated patches of volcanism unrelated to plate tectonics, may spring from surprisingly deep within the planet: the turbulent boundary between earth's mantle and its core.
That conclusion has arisen from intense study of a layer at the base of the mantle that apparently contains partially molten rock. UCSC researchers analyzed a peculiar type of seismic wave that skims along the sharp core-mantle boundary. In several regions, something bogs down the speed of the waves by about 10 percent--a huge amount by geophysical standards. The most likely cause, the researchers maintain, is that a small fraction of melted material bathes the mantle rock and transforms it into a dense mush.
The layer appears as thick as 20 kilometers in some regions-- notably under the south-central Pacific, Iceland, East Africa, and the Azores. These swaths of partial melt, notes UCSC mineral physicist Quentin Williams, lie 2,900 kilometers beneath some of the most well-known hot spots on the planet. "This may be the smoking gun that hot spots originate from the core-mantle boundary," Williams says.
Williams envisions a partially molten layer that becomes unstable at irregular intervals above the core-mantle boundary, welling up into thicker, stubby plumes. These zones would help heat flow with dispatch out of the liquid outer core and into the lower mantle. UCSC geophysicists discussed their work on December 17 at a meeting of the American Geophysical Union in San Francisco.
Contact: Quentin Williams--(408) 459-3132 or quentw@rupture.ucsc.edu
Paleoclimatology New way to gauge ages of stalactites may yield climate-change tool
The slow but relentless drippings of calcium-rich water in caves may open a new window on earth's past climate, thanks to a precise dating technique under development at UCSC.
Preserved within the stark beauty of stalactites and stalagmites are records of changes in the climate of the outside world. Their growth rates can document ups and downs in precipitation, while their chemical makeup (specifically, the ratio of particular isotopes of oxygen) can unmask ancient temperature fluctuations.
It's no simple matter to retrieve those records in a useful way. Scientists must know precisely when changes occurred in the growth rate or chemistry of a particular stalactite, but resolving those dates has proven devilishly difficult. That's the value of work by a UCSC research team, which adapted a technique used to date volcanic rocks with high precision.
Analyzing a stalactite from a California cave, the researchers measured ages from 8,500 years at its top to less than 800 years near its tip, with a precision of about 1 percent. They reported their work on December 15 at a meeting of the American Geophysical Union in San Francisco.
UCSC paleoclimatologist James Zachos hopes to apply the method to resolve the frequency of terrestrial climate changes in the last 20,000 years on timescales ranging from decades to millennia.
Contact: James Zachos--(408) 459-4644 or jzachos@rupture.ucsc.edu
Chemistry Cancer Society funds work to make promising anticancer compound
Since mid-1993, researchers in the laboratory of UCSC chemist Joseph Konopelski have tried to construct an intriguing substance harbored within the tissues of a tropical marine animal. The substance may be a potent weapon in the fight against cancer. But there's a problem: Less than a thimbleful of the material exists, and no one can relocate the obscure animal from which it came.
Konopelski's proposal to make the substance from scratch drew the attention of the American Cancer Society, which granted $319,000 for the first three years of the project. Now, encouraged by the UCSC team's progress, the society has renewed its support with $200,000 for the next two years.
The substance of interest to Konopelski, called "diazonamide A," comes from a soft-shelled animal that lived in a submarine cave off the coast of the Philippines. Tests showed that tiny amounts of the chemical killed colon-cancer cells in the lab. However, divers haven't been able to find the animal again. The best hope for further testing is for chemists to synthesize diazonamide A in the lab.
"This is just a fascinating molecule," says Konopelski. "The first time I saw the structure I knew it was something special. Nature wouldn't go to all this trouble unless it had something in mind. And this molecule is a lot of trouble, both for us and for nature."
Contact: Joseph Konopelski--(408) 459-4676 or joek@chemistry.ucsc.edu
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