6,248 research outputs found
An architecture for integrating distributed and cooperating knowledge-based Air Force decision aids
MITRE has been developing a Knowledge-Based Battle Management Testbed for evaluating the viability of integrating independently-developed knowledge-based decision aids in the Air Force tactical domain. The primary goal for the testbed architecture is to permit a new system to be added to a testbed with little change to the system's software. Each system that connects to the testbed network declares that it can provide a number of services to other systems. When a system wants to use another system's service, it does not address the server system by name, but instead transmits a request to the testbed network asking for a particular service to be performed. A key component of the testbed architecture is a common database which uses a relational database management system (RDBMS). The RDBMS provides a database update notification service to requesting systems. Normally, each system is expected to monitor data relations of interest to it. Alternatively, a system may broadcast an announcement message to inform other systems that an event of potential interest has occurred. Current research is aimed at dealing with issues resulting from integration efforts, such as dealing with potential mismatches of each system's assumptions about the common database, decentralizing network control, and coordinating multiple agents
Single-Shot Electron Diffraction using a Cold Atom Electron Source
Cold atom electron sources are a promising alternative to traditional
photocathode sources for use in ultrafast electron diffraction due to greatly
reduced electron temperature at creation, and the potential for a corresponding
increase in brightness. Here we demonstrate single-shot, nanosecond electron
diffraction from monocrystalline gold using cold electron bunches generated in
a cold atom electron source. The diffraction patterns have sufficient signal to
allow registration of multiple single-shot images, generating an averaged image
with significantly higher signal-to-noise ratio than obtained with unregistered
averaging. Reflection high-energy electron diffraction (RHEED) was also
demonstrated, showing that cold atom electron sources may be useful in
resolving nanosecond dynamics of nanometre scale near-surface structures.Comment: This is an author-created, un-copyedited version of an article
published in Journal of Physics B: Atomic, Molecular and Optical Physics. IOP
Publishing Ltd is not responsible for any errors or omissions in this version
of the manuscript or any version derived from it. The Version of Record is
available online at http://dx.doi.org/10.1088/0953-4075/48/21/21400
The Rise Times of High and Low Redshift Type Ia Supernovae are Consistent
We present a self-consistent comparison of the rise times for low- and
high-redshift Type Ia supernovae. Following previous studies, the early light
curve is modeled using a t-squared law, which is then mated with a modified
Leibundgut template light curve. The best-fit t-squared law is determined for
ensemble samples of low- and high-redshift supernovae by fitting simultaneously
for all light curve parameters for all supernovae in each sample. Our method
fully accounts for the non-negligible covariance amongst the light curve
fitting parameters, which previous analyses have neglected. Contrary to Riess
et al. (1999), we find fair to good agreement between the rise times of the
low- and high-redshift Type Ia supernovae. The uncertainty in the rise time of
the high-redshift Type Ia supernovae is presently quite large (roughly +/- 1.2
days statistical), making any search for evidence of evolution based on a
comparison of rise times premature. Furthermore, systematic effects on rise
time determinations from the high-redshift observations, due to the form of the
late-time light curve and the manner in which the light curves of these
supernovae were sampled, can bias the high-redshift rise time determinations by
up to +3.6/-1.9 days under extreme situations. The peak brightnesses - used for
cosmology - do not suffer any significant bias, nor any significant increase in
uncertainty.Comment: 18 pages, 4 figures, Accepted for publication in the Astronomical
Journal. Also available at http://www.lbl.gov/~nugent/papers.html Typos were
corrected and a few sentences were added for improved clarit
Appropriate Serological Testing in Pregnancy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72557/1/j.1423-0410.1992.tb01243.x.pd
High-power broadband laser source tunable from 3.0 um to 4.4 um based on a femtosecond Yb:fiber oscillator
We describe a tunable broadband mid-infrared laser source based on
difference-frequency mixing of a 100 MHz femtosecond Yb:fiber laser oscillator
and a Raman-shifted soliton generated with the same laser. The resulting light
is tunable over 3.0 um to 4.4 um, with a FWHM bandwidth of 170 nm and maximum
average output power up to 125 mW. The noise and coherence properties of this
source are also investigated and described.Comment: To appear in Optics Letter
DETECTION OF MORPHINE AND ITS ANALOGUES USING ENZYMATIC HYDROLYSIS
The invention relates to a method for hydrolyzing drug glucuronic acid conjugates present in mammalian body fluids, the conjugates being derived from a narcotic analgesic, antagonist, or agonist-antagonist whose metabolism includes conjugation with glucuronic acid. The method comprises incubating the body fluid sample at from about 60 to about 70° C., for at least about 1 hour, with 3-glucuronidase derived from Patella vulgata, and substantially increases the sensitivity of chromatographic techniques for the detection of morphine and its analogues
- …