1,996 research outputs found
Seismic Assessment of Syncrude Tailings Dyke
This paper describes the assessment of seismic risk at the Syncrude Site. It reviews the site physiographic and geologic setting and considers the site position relative to observed seismic events, strain release patterns, and main tectonic features in western Canada. Both deterministic and probabilistic approaches were employed in the seismic risk assessment. Data on seismic events that occurred between 1899 and 1985 were included in the evaluation. Of particular importance was determination of the impact on the site of a series of large earthquakes which occurred in the Nahanni area of the Northwest Territories during 1985. Hasegawa et al. (1981) attentuation relations were used for computing ground motion amplitudes at the site. The review confirmed that the seismic risk at the Syncrude Site remains low
The 1995-1996 Decline of R Coronae Borealis - High Resolution Optical Spectroscopy
A set of high-resolution optical spectra of RCrB acquired before, during, and
after its 1995-1996 decline is discussed. All of the components reported from
earlier declines are seen. This novel dataset provides new information on these
components including several aspects not previously seen in declines of RCrB
and other RCBs. In the latter category is the discovery that the decline's
onset is marked by distortions of absorption lines of high-excitation lines,
and quickly followed by emission in these and in low excitation lines. This
'photospheric trigger' implies that dust causing the decline is formed close to
the star. These emission lines fade quickly. After 1995 November 2, low
excitation narrow (FWHM ~12 km s-1) emission lines remain. These appear to be a
permanent feature, slightly blue-shifted from the systemic velocity, and
unaffected by the decline except for a late and slight decrease of flux at
minimum light. The location of the warm, dense gas providing these lines is
uncertain. Absorption lines unaffected by overlying sharp emission are greatly
broadened, weakened, and red-shifted at the faintest magnitudes when scattered
light from the star is a greater contributor than direct light transmitted
through the fresh soot cloud. A few broad lines are seen at and near minimum
light with approxiamately constant flux: prominent among these are the He I
triplet series, Na I D, and [N II] lines. These lines are blue-shifted by about
30 km s(-1) relative to the systemic velocity with no change in velocity over
the several months for whicht he lines were seen. It is suggested that these
lines, especially the He I lines, arise from an accretion disk around an unseen
compact companion, which may be a low-mass white dwarf. If so, R CrB is similar
to the unusual post-AGB star 89 Her.Comment: 31 pages, 26 figure
Balancing the demands of validity and reliability in practice: case study of a changing system of primary science summative assessment
Teacher summative judgements of children’s attainment in science, which are statutory at age 11 in England, require consideration of both valid sampling of the construct and reliable comparison of outcomes. In order to develop understanding of the enacted ‘trade off’ between validity and reliability, this three-year case study, within the Teacher Assessment in Primary Science (TAPS) project, was undertaken during a period of statutory assessment change in England. The case demonstrates an ongoing balancing act between the demands of reliability and validity, and resulted in the development of a teacher assessment seesaw, which provides a model for both interpreting and supporting practice, within and beyond primary science
Effect of recent R_p and R_n measurements on extended Gari-Krumpelmann model fits to nucleon electromagnetic form factors
The Gari-Krumpelmann (GK) models of nucleon electromagnetic form factors, in
which the rho, omega, and phi vector meson pole contributions evolve at high
momentum transfer to conform to the predictions of perturbative QCD (pQCD), was
recently extended to include the width of the rho meson by substituting the
result of dispersion relations for the pole and the addition of rho' (1450)
isovector vector meson pole. This extended model was shown to produce a good
overall fit to all the available nucleon electromagnetic form factor (emff)
data. Since then new polarization data shows that the electric to magnetic
ratios R_p and R_n obtained are not consistent with the older G_{Ep} and G_{En}
data in their range of momentum transfer. The model is further extended to
include the omega' (1419) isoscalar vector meson pole. It is found that while
this GKex cannot simultaneously fit the new R_p and the old G_{En} data, it can
fit the new R_p and R_n well simultaneously. An excellent fit to all the
remaining data is obtained when the inconsistent G_{Ep} and G_{En} is omitted.
The model predictions are shown up to momentum transfer squared, Q^2, of 8
GeV^2/c^2.Comment: 14 pages, 8 figures, using RevTeX4; email correspondence to
[email protected] ; minor typos corrected, figures added, conclusions
extende
Improved Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant
The mean life of the positive muon has been measured to a precision of 11 ppm
using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which
was surrounded by a scintillator detector array. The result, tau_mu =
2.197013(24) us, is in excellent agreement with the previous world average. The
new world average tau_mu = 2.197019(21) us determines the Fermi constant G_F =
1.166371(6) x 10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of
the positive muon lifetime is needed to determine the nucleon pseudoscalar
coupling g_P.Comment: As published version (PRL, July 2007
Establishing a collaborative governance structure at an academic medical center for global health programs in resource-limited settings
A Census of the High-Density Molecular Gas in M82
We present a three-pointing study of the molecular gas in the starburst
nucleus of M82 based on 190 - 307 GHz spectra obtained with Z-Spec at the
Caltech Submillimeter Observatory. We present intensity measurements,
detections and upper limits, for 20 transitions, including several new
detections of CS, HNC, C2H, H2CO, and CH3CCH lines. We combine our measurements
with previously-published measurements at other frequencies for HCN, HNC, CS,
C34S, and HCO+ in a multi-species likelihood analysis constraining gas mass,
density and temperature, and the species' relative abundances. We find some 1.7
- 2.7 x 10^8 M_sun of gas with n_H2 between 1 - 6 x 10^4 cm^-3 and T > 50 K.
While the mass and temperature are comparable to values inferred from mid-J CO
transitions, the thermal pressure is a factor of 10 - 20 greater. The molecular
interstellar medium is largely fragmented and is subject to ultraviolet
irradiation from the star clusters. It is also likely subject to cosmic rays
and mechanical energy input from the supernovae, and is warmer on average than
the molecular gas in the massive star formation regions in the Milky Way. The
typical conditions in the dense gas in M82's central kpc appear unfavorable for
further star formation; if any appreciable stellar populations are currently
forming, they are likely biased against low mass stars, producing a top-heavy
initial mass function.Comment: 15 pages (using emulateapj.cls), 6 figures, Astrophysical Journal, in
pres
The Ursinus Weekly, March 18, 1971
Flott on Indo-China, Richette on justice featured in Forums • Students criticize curriculum; art expansion most favored • Know your rights • State of our prisons: Ursinus students succeed at breaking in • Editorial: Ready or not, here we come • Letters to the editor: Parting shot; One year later; Plaid panned; Off the grass; Pathetic reformers • Movie critic: Academy awards • Faculty portrait: Dr. John J. Heilemann • Trackmen grab MAC title • UC grapplers finish 8-2, best season in 15 yearshttps://digitalcommons.ursinus.edu/weekly/1141/thumbnail.jp
Implementing international standards for facility management in healthcare facilities in resource-limited settings
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