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In this issue:
Strong Focus on Test Beams
Science Today: Revealing the Molecular Origins of Life
Memorial Service to Honor Albert Baez

SLAC Today

Thursday - May 17, 2007

SLAC Physicists Janice Nelson (at SLAC) and Tonee Smith (at KEK) set up the beam based alignment at the ATF during a recent "remote participation" shift. The top monitors display ATF control system data. (Click on image for larger version.)

Strong Focus on Test Beams

On the opposite rim of the Pacific Ocean, a group of SLAC physicists are part of the international team helping to expand the Accelerator Test Facility (ATF) at the Japanese lab KEK.

The ATF already makes some of the world's most tightly focused beams, measured in the vertical direction. Upgrades now underway will make the ATF2 an unprecedented tool to help researchers better understand how to focus beams down to minute sizes, a requirement for colliding the electron and positron beams at the proposed International Linear Collider (ILC).

In addition to sending people to KEK regularly—three SLAC physicists are there now—the group is launching remote participation. Researchers here at SLAC can sit at computers displaying ATF operations and talk to accelerator operators, as if they were sitting in the control room an ocean away.

"It's very exciting to work internationally. To make it easier on travel budgets and researchers' time, we're starting remote participation. It has the potential to involve a lot more collaborators and students in ATF2 work," said Andrei Seryi, project leader for SLAC's ATF2 efforts.  Read more...

(Daily Column - Science Today)

Revealing the Molecular Origins of Life

(Image - L1 ligase active site)
A close-up of the L1 ligase active site.

Researchers from the University of California, Santa Cruz, using macromolecular crystallography beam line 9-1 at the Stanford Synchrotron Radiation Laboratory (SSRL) have determined the three-dimensional structure of an RNA enzyme, or "ribozyme," that carries out a fundamental reaction required to make new RNA molecules. Their results provide insight into what may have been the first self-replicating molecule to arise billions of years ago on the evolutionary path toward the emergence of life. The findings are published in the March 16 issue of the journal Science.

William Scott and postdoctoral researcher Michael Robertson determined the structure of a ribozyme that joins two RNA subunits together in the same reaction that is carried out in biological systems by the protein known as RNA polymerase. The ribozyme used in the study is not an entirely self-replicating RNA molecule, but it does carry out the fundamental reaction required of such a molecule—a "ligase" reaction creating a bond between two RNA subunits.

The ribozyme has three stems that radiate from a central hub. The active site where ligation occurs is located on one stem, and the structure shows that the molecule folds in such a way that parts of another stem are positioned over the ligation site, forming a pocket where the reaction takes place. A magnesium ion bound to one stem and positioned in the pocket plays an important role in the reaction, Robertson said.

Learn more...

Memorial Service to Honor Albert Baez

A memorial honoring Albert Vinicio Baez—physicist, pacifist and father of three daughters including folk singers Joan Baez and the late Mimi FariƱa—will be held Thursday, May 24, at 4:00 p.m. in Stanford's Memorial Church. The gathering, held in the style of the Society of Friends, is open to the public. 

Albert Baez, who co-invented the x-ray reflection microscope with Stanford physics Professor Paul Kirkpatrick in 1948, earned his physics doctorate from Stanford in 1950. He died of natural causes March 20 at the Redwood City care home where he had lived the past three years. He was 94.

Born in Puebla, Mexico, on Nov. 15, 1912, Baez was the son of a Methodist minister who brought his family to the United States when Albert was 2. He grew up in Brooklyn, where his mother was a social worker for the YMCA.

He earned a bachelor's degree in mathematics from Drew University in 1933 and a master's degree in physics from Syracuse University in 1935. In 1936, he married Joan Chandos Bridge, the daughter of an Episcopalian minister. The couple became Quakers and had three daughters.

During his graduate studies at Stanford, he developed the optics for x-rays that decades later would enable special microscopes and telescopes, said George Castro, a retired IBM scientist who published a journal article with Baez. For his thesis work, Baez with Kirkpatrick developed a way to use a pair of mirrors at right angles to focus x-rays, Castro said.

But a problem hindered the immediate utility of mirror pairs. Light hit the mirrors at a tiny angle. That meant the mirrors could catch only a small fraction of light from the x-rays. The mirrors weren't of much use until narrow, brilliant x-ray beams were produced to enable brighter images.  Read more....

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