Best "Rulers" Will Make Better Clocks
Bruce Erik Steffine
physicist Scott Diddams adjusts a femtosecond laser
system that is an important component of next-generation
atomic clocks based on optical rather than microwave
that emit pulses of light lasting just 10 femtoseconds (10 quadrillionths
of a second) can reliably measure time and frequency more
precisely than any other "rulers," according
to recent tests conducted at the National Institute of Standards
and Technology (NIST).
demonstrated that femtosecond laser devices could be used to
reproducibly generate and accurately control wavelengths of
light to serve as the "gears" that translate ultrahigh
frequency "ticks" from next-generation optical atomic
clocks into practical electronics-based timekeeping. Applications
for ultra-precise timekeeping include navigation, telecommunications
and basic scientific research.
are called "frequency combs" because a graph of the
oscillating electromagnetic waves looks like the teeth of a
hair comb. The experiments are the first to compare the operation
of multiple femtosecond frequency combs—thereby demonstrating
reproducibility—and to verify that both the starting position
of a comb and the spacing between the teeth can be controlled
described in the March 19, 2004, issue of the journal Science,
is a significant step toward next-generation "atomic clocks"
based on optical rather than microwave frequencies. Such clocks
are expected to be as much as 100 times more accurate than today's
best timekeeping systems. A frequency comb would work like the
gears in a transmission to convert the very fast oscillations
of optical clocks into lower frequency signals that can be compared
with current primary timekeeping standards based on microwave
sources. The signal then could be distributed with conventional
electronics through the Global Positioning System and broadcasts
from NIST's time signal radio stations.
team compared the operation of four femtosecond laser systems
of different designs—two built at NIST, one by the Bureau
International des Poids et Mesures in France, and one by East
China Normal University in Shanghai. The three labs collaborated
on the tests along with OFS Laboratories in New Jersey.
information, see www.nist.gov/public_affairs/releases/bestrulers.htm
Ost, (301) 975-4034
Helps ID Fuels Used in Arson
with a growing number of ignitable chemicals with similar characteristics,
arson investigators have their hands full trying to tell residues
of insecticide, for example, from those of gasoline. But identifying
fuels used to set fires will be easier now, thanks to some help
from the National Institute of Standards and Technology (NIST).
agencies, insurance fraud investigators and forensic services
are expected to use Standard Reference Material (SRM) 2285,
NIST's first standard intended to aid arson investigations.
The new SRM is a liquid containing 15 compounds from common
accelerants in various certified concentrations. It will be
used to calibrate instruments that help analysts classify fire
scene residues into six categories of fuels.
compounds are separated and identified based on how long it
takes for them to pass through an instrument called a gas chromatograph.
The retention time depends partly on a compound's volatility,
or how fast it changes from liquid to vapor, and partly on experimental
conditions such as temperature. Users analyze the SRM, analyze
the residue from the crime scene and compare the retention time
patterns to help identify the components used at the fire.
readouts indicate both the presence and concentration of the
various components; these patterns may indicate a particular
fuel source. In helping investigators accurately identify the
components and thus the original fuel used to set a fire, the
SRM may help improve the 2 percent national conviction rate
for arson cases. SRM 2285 also may be useful in the petroleum
industry and environmental science.
Ost, (301) 975-4034
Appeared Before "Junk" DNA
rigorous statistical analysis of so-called "junk" DNA
from a wide variety of biological kingdoms (plants, animals, fungi,
etc.) has shown that this mysterious genetic material was added
late in the evolution of life on earth—after
the formation of modern-sized genes that contain instructions
for making proteins.
new research appears to resolve a debate about whether "introns"—sections
of DNA with unknown function plopped in the middle of genes—were
present in ancient life forms or appeared for the first time after
bacteria and higher organisms split into separate evolutionary
paths billions of years ago.
work was conducted at the Center for Advanced Research in Biotechnology
(CARB), which is jointly operated by the National Institute of
Standards and Technology (NIST) and the University of Maryland
Biotechnology Institute. A Furman University researcher collaborated
on the project. Their findings are reported in the March 10 online
edition of Molecular Biology and Evolution.
publicly available genetics sequences, the CARB study analyzed
data for 10 families of protein-coding genes in animals, plants,
fungi and their relatives, encompassing 1,868 introns at 488 different
positions. While most such studies work with one genetic sequence
family at a time, the CARB study developed software to automate
the analysis of dozens of sequence families simultaneously.
new results refute a once-popular theory that introns may have
served as genetic glue to assemble modern-sized genes out of ancient
mini-genes. The CARB analysis shows that the probability of a
modern intron's presence in an ancestral gene common to the genes
studied is roughly 1 percent, indicating that the vast majority
of today's introns appeared after the origin of the genes.
further information, see http://www.nist.gov/public_affairs/newsfromnist_junkdna.htm.
Ost, (301) 975-4034
for Evaluating Public R&D Funding
hard to measure innovation. While public support for research
and development long has
been recognized as an important
tool for enhancing economic growth, determining which programs
are most effective has been problematic for just as long.
Advanced Technology Program (ATP) at the National Institute
of Standards and Technology (NIST) has more than 14 years of
experience evaluating R&D and has been recognized by the
National Research Council for setting “a high standard
for assessment.” Using a variety of research tools, including
surveys, econometric models, detailed case studies and literature
analysis, ATP economists have assembled a significant body of
research and data on the innovation process and contributed
to the development of the academic theory on assessing R&D
new ATP publication, A Toolkit for Evaluating Public R&D
Investment, assembles in one volume a decade’s worth
of ATP experience in the measurement of innovation, including
a general framework for evaluation, a discussion of an evaluation
logic model, fundamentals and methods, demonstrations of the
ATP’s use of evaluation methods, and a summary of an emerging
body of knowledge from ATP studies on firm behavior, collaboration,
spillover effects, interfaces with state and international technology
programs, and the overall performance of the program. It also
includes a glossary of terms, methods bibliography and a quick
reference guide to evaluation models and methods.
copies of the toolkit are available by writing the Economic
Assessment Office, Advanced Technology Program, NIST, 100 Bureau
Drive, Mail Stop 4710, Gaithersburg, MD 20899-4710, or by sending
an e-mail to email@example.com.
The report also is available on-line at www.atp.nist.gov/eao/gcr03-857/contents.htm.
Baum, (301) 975-2763
Information Science and Emerging Technologies—A
workshop designed to engage industry representatives in
a continuing dialogue with the National Institute of Standards
and Technology (NIST) and other federal agencies on emerging
quantum information technologies will take place on April
28-30, 2004, at NIST's facilities in Boulder, Colo. The
meeting will provide an introduction to quantum computing
and communications, descriptions of current research results
in the field, a review of federal perspectives, and opportunities
for industry comment on NIST program directions. For further
information, see www.nist.gov/public_affairs/confpage/new040428.htm.
Research Library and Librarian Receive Top Honors—The
Federal Library and Information Center Committee at
the Library of Congress recently named the NIST Research
Library as its Federal Library/Information Center of
the Year. The NIST library was recognized "for
its technological innovations and comprehensive knowledge
management systems that proactively provide the tools
necessary to support new programs, superior customer
service and the agency mission." Additionally,
NIST's Wilma (Sissy) Riley was named Federal Library
Technician of the Year. For more details, go to www.loc.gov/today/pr/2004/04-049.html.
to NIST News Page)
Date updated: 3/22/2004