3,295 research outputs found
Re Int\u27l Moulders Union and Jamaica MFG (Canada) Ltd
The facts essential to the settlement of this grievance do not appear to be in dispute. Employees of the company are paid an hourly base rate, as set out in the schedule to the collective agreement, plus incentive pay. The incentive system operates. wholly outside the agreement except for references in art. 10 (c), which is quoted below, and upon which this grievance is based. There are several indirect references to the incentive scheme in the Wage Schedule and Classifications appended to the agreement. The references in the schedule do no more than testify to the existence of the incentive system. The system in use is a standard allowed time method of calculating bonus payments
The Effect of Ionic Dissolution Products of Ca-Sr-Na-Zn-Si Bioactive Glass on in Vitro Cytocompatibility
Many commercial bone grafts cannot regenerate healthy bone in place of diseased bone. Bioactive glasses have received much attention in this regard due to the ability of their ionic dissolution products to promote cell proliferation, cell differentiation and activate gene expression. Through the incorporation of certain ions, bioactive glasses can become therapeutic for specific pathological situations. Calcium-strontium-sodium-zinc-silicate glass bone grafts have been shown to release therapeutic levels of zinc and strontium, however the in vitro compatibility of these materials is yet to be reported. In this study, the in vitro cytocompatibility of three different calcium-strontium-sodium-zinc-silicate glasses was examined as a function of their ion release profiles, using NovaboneŸ bioglass as a commercial comparison. Experimental compositions were shown to release Si4+ ranging from 1 to 81 ppm over 30 days; comparable or enhanced release in comparison to Novabone. The maximum Ca2+ release detected for experimental compositions was 9.1 ppm, below that reported to stimulate osteoblasts. Sr2+ release was within known therapeutic ranges, and Zn2+ release ranged from 0.5 to 1.4 ppm, below reported cytotoxic levels. All examined glass compositions show equivalent or enhanced in vitro compatibility in comparison to Novabone. Cells exposed to BT112 ionic products showed enhanced cell viabilities indicating cell proliferation was induced. The ion release profiles suggest this effect was due to a synergistic interaction between certain combinations and concentrations of ions. Overall, results indicate that the calcium-strontium-sodium-zinc-silicate glass compositions show equivalent or even enhanced in vitro compatibility compared to NovaboneŸ. © 2010 Springer Science+Business Media, LLC
RAPTOR observations of delayed explosive activity in the high-redshift gamma-ray burst GRB 060206
The RAPid Telescopes for Optical Response (RAPTOR) system at Los Alamos
National Laboratory observed GRB 060206 starting 48.1 minutes after gamma-ray
emission triggered the Burst Alert Telescope (BAT) on-board the Swift
satellite. The afterglow light curve measured by RAPTOR shows a spectacular
re-brightening by ~1 mag about 1 h after the trigger and peaks at R ~ 16.4 mag.
Shortly after the onset of the explosive re-brightening the OT doubled its flux
on a time-scale of about 4 minutes. The total R-band fluence received from GRB
060206 during this episode is 2.3e-9 erg/cm2. In the rest frame of the burst (z
= 4.045) this yields an isotropic equivalent energy release of ~0.7e50 erg in
just a narrow UV band 130 +/- 22 nm. We discuss the implications of RAPTOR
observations for untriggered searches for fast optical transients and studies
of GRB environments at high redshift.Comment: Submitted to ApJ Letter
Evidence for Post-Quiescent, High-Energy Emission from Gamma-Ray Burst 990104
It is well known that high-energy emission (MeV-GeV) has been observed in a
number of gamma-ray bursts, and temporally-extended emission from lower energy
gamma rays through radio wavelengths is well established. An important observed
characteristic of some bursts at low energy is quiescence: an initial emission
followed by a quiet period before a second (postquiescent) emission. Evidence
for significant high-energy, postquiescent emission has been lacking. Here we
present evidence for high-energy emission, coincident with lower energy
emission, from the postquiescent emission episode of the very bright and long
burst, GRB 990104. We show light curves and spectra that confirm emission above
50 MeV, approximately 152 seconds after the BATSE trigger and initial emission
episode. Between the initial emission episode and the main peak, seen at both
low and high energy, there was a quiescent period of ~100 s during which the
burst was relatively quiet. This burst was found as part of an ongoing search
for high-energy emission in gamma-ray bursts using the EGRET fixed interval (32
s) accumulation spectra, which provide sensitivity to later, high-energy
emission that is otherwise missed by the standard EGRET BATSE-triggered burst
spectra.Comment: 5 pages, including 5 figures. Missing citation added to introduction.
Accepted for publication in ApJ
A scalable machine-learning approach to recognize chemical names within large text databases
MOTIVATION: The use or study of chemical compounds permeates almost every scientific field and in each of them, the amount of textual information is growing rapidly. There is a need to accurately identify chemical names within text for a number of informatics efforts such as database curation, report summarization, tagging of named entities and keywords, or the development/curation of reference databases. RESULTS: A first-order Markov Model (MM) was evaluated for its ability to distinguish chemical names from words, yielding ~93% recall in recognizing chemical terms and ~99% precision in rejecting non-chemical terms on smaller test sets. However, because total false-positive events increase with the number of words analyzed, the scalability of name recognition was measured by processing 13.1 million MEDLINE records. The method yielded precision ranges from 54.7% to 100%, depending upon the cutoff score used, averaging 82.7% for approximately 1.05 million putative chemical terms extracted. Extracted chemical terms were analyzed to estimate the number of spelling variants per term, which correlated with the total number of times the chemical name appeared in MEDLINE. This variability in term construction was found to affect both information retrieval and term mapping when using PubMed and Ovid
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Preparation of a novel drug sensor using a molecular imprinted polymer approach
A chemical sensor for the detection of cocaine has been developed, based on a molecularly imprinted polymer (MIP) containing a fluorescein moiety as the signalling group. The fluorescent MIP was formed and covalently attached to the distal end of an optical fibre. The sensor exhibited an increase in fluorescence intensity in response to cocaine in an aqueous acetonitrile mixture. Selectivity for cocaine over codeine has been demonstrated
ROTSE All Sky Surveys for Variable Stars I: Test Fields
The ROTSE-I experiment has generated CCD photometry for the entire Northern
sky in two epochs nightly since March 1998. These sky patrol data are a
powerful resource for studies of astrophysical transients. As a demonstration
project, we present first results of a search for periodic variable stars
derived from ROTSE-I observations. Variable identification, period
determination, and type classification are conducted via automatic algorithms.
In a set of nine ROTSE-I sky patrol fields covering about 2000 square degrees
we identify 1781 periodic variable stars with mean magnitudes between m_v=10.0
and m_v=15.5. About 90% of these objects are newly identified as variable.
Examples of many familiar types are presented. All classifications for this
study have been manually confirmed. The selection criteria for this analysis
have been conservatively defined, and are known to be biased against some
variable classes. This preliminary study includes only 5.6% of the total
ROTSE-I sky coverage, suggesting that the full ROTSE-I variable catalog will
include more than 32,000 periodic variable stars.Comment: Accepted for publication in AJ 4/00. LaTeX manuscript. (28 pages, 11
postscript figures and 1 gif
The Afterglow, Energetics and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221a
We present detailed optical, X-ray and radio observations of the bright
afterglow of the short gamma-ray burst 051221a obtained with Gemini, Swift/XRT,
and the Very Large Array, as well as optical spectra from which we measure the
redshift of the burst, z=0.5464. At this redshift the isotropic-equivalent
prompt energy release was about 1.5 x 10^51 erg, and using the standard
afterglow synchrotron model we find that the blastwave kinetic energy is
similar, E_K,iso ~ 8.4 x 10^51 erg. An observed jet break at t ~ 5 days
indicates that the opening angle is ~ 7 degrees and the total beaming-corrected
energy is therefore ~ 2.5 x 10^49 erg, comparable to the values inferred for
previous short GRBs. We further show that the burst experienced an episode of
energy injection by a factor of 3.4 between t=1.4 and 3.4 hours, which was
accompanied by reverse shock emission in the radio band. This result provides
continued evidence that the central engines of short GRBs may be active
significantly longer than the duration of the burst and/or produce a wide range
of Lorentz factors. Finally, we show that the host galaxy of GRB051221a is
actively forming stars at a rate of about 1.6 M_solar/yr, but at the same time
exhibits evidence for an appreciable population of old stars (~ 1 Gyr) and near
solar metallicity. The lack of bright supernova emission and the low
circumburst density (n ~ 10^-3 cm^-3) continue to support the idea that short
bursts are not related to the death of massive stars and are instead consistent
with a compact object merger. Given that the total energy release is a factor
of ~ 10 larger than the predicted yield for a neutrino annihilation mechanism,
this suggests that magnetohydrodynamic processes may be required to power the
burst.Comment: Final version (to appear in ApJ on 20 September 2006
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