SLAC Today is available online at:
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In this issue:
A Glimpse of the Future: Spin-polarized Computing
Colloquium: Decreasing the Damage of Radiotherapy and Chemotherapy
KIPAC Researchers Talk Black Holes with Students

SLAC Today

Friday - June 2, 2006

Diagram showing how the polarity of a magnetic bit changes when injected with a spin-polarized current. To change from a one to a zero, the arrows in panel (a) should flip to the opposite direction. Acremann and his team discovered the movement of the arrows is more complicated than originally suspected.

A Glimpse of the Future:
Spin-polarized Computing

Imagine a computer that never has to boot up—flip the switch and it's immediately on, turn it off and it never loses information.

Home computers today can not pull this off because of a gap in the two types of computer memory currently in use. Random access memory (RAM) is where most computer processes take place. RAM chips are fast, but they lose information as soon as the power is turned off. Hard disks are where operating software is stored. They are inexpensive and retain information even after being switched off, but they are large, slow mechanical devices. To make computers faster and more reliable, researchers now seek to combine the positive attributes of both RAM and hard disks. 

A novel candidate for achieving this is the magnetic random access memory chip, in which the information is stored magnetically on a chip which allows fast access to the information.  Read more...

Colloquium Monday

Decreasing the Damage of Radiotherapy and Chemotherapy


(Image - Colloquium poster) On Monday, June 5, Dr. Richard Blankenbecler will present the colloquium "Reducing Radiation Damage from Radiotherapy and Chemotherapy" at 4:15 p.m. in Panofsky Auditorium.

In his talk, Blankenbecler will describe ways to mitigate some of the deleterious effects of cancer radiotherapy.  Specifically, he will focus on the harnessing of natural cell repair processes. If bad side effects can be reduced, a more aggressive therapy can be put into place.

Cells contain many mechanisms that repair damage of various types. If the damage can not be repaired, cells will die.

Blankenbecler will present data showing that a small dose of radiation can activate damage repair genes within a cell. Once these mechanisms are fully active, they have been shown to efficiently repair the severe damage from a much larger radiation dose. The data ranges from experiments on specific cell cultures using microarray (gene chip) techniques to experiments on complete organisms.

All radiation is harmful, no matter how small the dose. Nevertheless, Blankenbecler's data suggests that the harm can be reduced. These mechanisms need to be further studied and characterized. In particular, their time-dependence needs to be understood before the proposed treatment can be optimized. Under certain situations it is also possible that the negative effects of chemotherapy can be mitigated and the damage to radiation workers can be reduced. Learn more...

KIPAC Researchers Talk Black Holes with Students

(Photo - Students) Phil Marshall demonstrates the bending of space-time to a third and fourth grade class at Orion School. (Click on image for larger version.)

A black hole showed up in a local elementary school Wednesday morning.

Pulling a tablecloth out of a bowling bag, Phil Marshall of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) and his colleagues demonstrated the fabric of space-time. To do this, Marshall placed a bowling ball—the black hole—in the center of the cloth—space-time. The third and fourth grade students at Orion School in Redwood City lifted the edges, watching how the mass altered the fabric.

John Glover's students have been studying astronomy all year. Three of them have parents who work at SLAC. Steven von Fuerst, Teddy Cheung and Marshall, all KIPAC postdocs, fielded the students' numerous questions, which mainly concerned what black holes can "suck up."

Yes, Fuerst said, a black hole can eat another black hole, a star, a planet, even a galaxy. However, "most things in outer space miss each other. Space is really big and really empty," he said.

What from the presentation will the students remember? When asked, the students offered diverse answers: black holes get bigger when they eat; they can't eat everything; the jets they spit out look like volcanoes; things can escape from a black hole very, very slowly; and black holes can suck up a galaxy.

After their presentation, the personable researchers returned the black hole safely to its bag, where it awaits its next classroom visit.

If you are involved in education outreach efforts, the Education Task Force would love to hear about it. Education Contact: Mike Woods, x3609.

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