5,927 research outputs found
Post-Chernobyl 134Cs and 137Cs Levels at Some Localities in Northern Canada
Samples of lichen, moss and caribou meat from the high and central arctic regions of Canada were measured for 137Cs due to the Chernobyl accident of April 1986. They were compared to lichen samples from the boreal area of Wood Buffalo National Park, Alberta, and to moss samples from the temperate Niagara Escarpment of southern Ontario. Lichens from Ellesmere Island and mosses from the Niagara Escarpment had no detectable Chernobyl 137Cs. Lichens from the central Arctic showed a 137Cs increase of about 14% above the persistent burden from the past atmospheric nuclear weapons testing. Mosses and lichens from Wood Buffalo National Park showed an average 137Cs increase of 19% due to Chernobyl fallout. In absolute terms, the contribution of Chernobyl fallout over Canadian northern regions was non-significant compared to the depositions experienced by countries such as the U.S.S.R., Sweden, Norway and some Central European countries.Key words: Chernobyl, 134.137Cesium, fallout radionuclides in northern Canada, lichen samples, caribou samplesMots clés: Chernobyl, 1343137Césium, retombées de radionucléides dans le Nord canadien, échantillons de lichens, échantillons de caribo
Masculinity as Governance: police, public service and the embodiment of authority, c. 1700-1850
About the book: Public Men offers an introduction to an exciting new field: the history of masculinities in the political domain and will be essential reading for students and specialists alike with interests in gender or political culture. By building upon new work on gender and political culture, these new case studies explore the gendering of the political domain and the masculinities of the men who have historically dominated it. As such, Public Men is a major contribution to our understanding of the history of Britain between the Eighteenth and the Twentieth centuries
Scintillation and charge extraction from the tracks of energetic electrons in superfluid helium-4
An energetic electron passing through liquid helium causes ionization along
its track. The ionized electrons quickly recombine with the resulting positive
ions, which leads to the production of prompt scintillation light. By applying
appropriate electric fields, some of the ionized electrons can be separated
from their parent ions. The fraction of the ionized electrons extracted in a
given applied field depends on the separation distance between the electrons
and the ions. We report the determination of the mean electron-ion separation
distance for charge pairs produced along the tracks of beta particles in
superfluid helium at 1.5 K by studying the quenching of the scintillation light
under applied electric fields. Knowledge of this mean separation parameter will
aid in the design of particle detectors that use superfluid helium as a target
material.Comment: 10 pages, 8 figure
Promiscuity in the part-phosphorylative EntnerâDoudoroff pathway of the archaeon Sulfolobus solfataricus
AbstractThe hyperthermophilic archaeon Sulfolobus solfataricus metabolises glucose and galactose by a âpromiscuousâ non-phosphorylative variant of the EntnerâDoudoroff pathway, in which a series of enzymes have sufficient substrate promiscuity to permit the metabolism of both sugars. Recently, it has been proposed that the part-phosphorylative EntnerâDoudoroff pathway occurs in parallel in S. solfataricus as an alternative route for glucose metabolism. In this report we demonstrate, by in vitro kinetic studies of d-2-keto-3-deoxygluconate (KDG) kinase and KDG aldolase, that the part-phosphorylative pathway in S. solfataricus is also promiscuous for the metabolism of both glucose and galactose
IRAS03063+5735: A Bowshock Nebula Powered by an Early B Star
Mid-infrared images from the Spitzer Space Telescope Galactic Legacy Infrared
MidPlane Survey Extraordinaire program reveal that the infrared source IRAS
03063+5735 is a bowshock nebula produced by an early B star, 2MASS
03101044+5747035. We present new optical spectra of this star, classify it as a
B1.5 V, and determine a probable association with a molecular cloud complex at
V_LSR=-38 -- -42 km/s in the outer Galaxy near l=140.59 degr, b=-0.250 degr. On
the basis of spectroscopic parallax, we estimate a distance of 4.0 +/-1 kpc to
both the bowshock nebula and the molecular complex. One plausible scenario is
that this a high-velocity runaway star impinging upon a molecular cloud. We
identify the HII region and stellar cluster associated with IRAS 03064+5638 at
a projected distance of 64 pc as one plausible birth site. The
spectrophotometric distance and linkage to a molecular feature provides another
piece of data helping to secure the ill-determined rotation curve in the outer
Galaxy. As a by-product of spectral typing this star, we present empirical
spectral diagnostic diagrams suitable for approximate spectral classification
of O and B stars using He lines in the little-used yellow-red portion of the
optical spectrum.Comment: Accepted for publication in the Astronomical Journa
The (p,q) String Tension in a Warped Deformed Conifold
We find the tension spectrum of the bound states of p fundamental strings and
q D-strings at the bottom of a warped deformed conifold. We show that it can be
obtained from a D3-brane wrapping a 2-cycle that is stabilized by both electric
and magnetic fluxes. Because the F-strings are Z_M-charged with non-zero
binding energy, binding can take place even if (p,q) are not coprime.
Implications for cosmic strings are briefly discussed.Comment: 17 pages, 1 figur
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Circulating Biomarkers to Identify Responders in Cardiac Cell therapy.
Bone marrow mononuclear cell (BM-MNC) therapy in ST-elevation acute myocardial infarction (STEMI) has no biological inclusion criteria. Here, we analyzed 63 biomarkers and cytokines in baseline plasma samples from 77 STEMI patients treated with BM-MNCs in the TIME and Late-TIME trials as well as 61 STEMI patients treated with placebo. Response to cell therapy was defined by changes in left ventricular ejection fraction, systolic/diastolic volumes, and wall motion indexes. We investigated the clinical value of circulating proteins in outcome prediction using significance testing, partial least squares discriminant analysis, and receiver operating characteristic (ROC) analysis. Responders had higher biomarker levels (76-94% elevated) than non-responders. Several biomarkers had values that differed significantly (Pâ<â0.05) between responders and non-responders including stem cell factor, platelet-derived growth factor, and interleukin-15. We then used these lead candidates for ROC analysis and found multiple biomarkers with values areas under the curve >0.70 including interleukin 15. These biomarkers were not involved in the placebo-treated subjects suggesting that they may have predictive power. We conclude that plasma profiling after STEMI may help identify patients with a greater likelihood of response to cell-based treatment. Prospective trials are needed to assess the predictive value of the circulating biomarkers
HST Emission Line Galaxies at z ~ 2: Comparing Physical Properties of Lyman Alpha and Optical Emission Line Selected Galaxies
We compare the physical and morphological properties of z ~ 2 Lyman-alpha
emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band
studies with those of z ~ 2 optical emission line galaxies (oELGs) identified
via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the
same range in stellar mass (7.5 < logM < 10.5), size (0.5 < R < 3.0 kpc), and
star-formation rate (~1 < SFR < 100). Remarkably, a comparison of the most
commonly used physical and morphological parameters -- stellar mass, half-light
radius, UV slope, star formation rate, ellipticity, nearest neighbor distance,
star formation surface density, specific star formation rate, [O III]
luminosity, and [O III] equivalent width -- reveals no statistically
significant differences between the populations. This suggests that the
processes and conditions which regulate the escape of Ly-alpha from a z ~ 2
star-forming galaxy do not depend on these quantities. In particular, the lack
of dependence on the UV slope suggests that Ly-alpha emission is not being
significantly modulated by diffuse dust in the interstellar medium. We develop
a simple model of Ly-alpha emission that connects LAEs to all high-redshift
star forming galaxies where the escape of Ly-alpha depends on the sightline
through the galaxy. Using this model, we find that mean solid angle for
Ly-alpha escape is 2.4+/-0.8 steradians; this value is consistent with those
calculated from other studies.Comment: Accepted to the ApJ. 32 pages, 4 figures, and 2 table
CO Emission in Low Luminosity, HI Rich Galaxies
We present 12CO 1-0 observations of eleven low luminosity M_B > -18),
HI--rich dwarf galaxies. Only the three most metal-rich galaxies, with
12+log(O/H) ~ 8.2, are detected. Very deep CO spectra of six extremely
metal-poor systems (12+log(O/H) < 7.5) yield only low upper limits on the CO
surface brightness, I_CO < 0.1 K km/s. Three of these six have never before
been observed in a CO line, while the others now have much more stringent upper
limits. For the very low metallicity galaxy Leo A, we do not confirm a
previously reported detection in CO, and the limits are consistent with another
recent nondetection. We combine these new observations with data from the
literature to form a sample of dwarf galaxies which all have CO observations
and measured oxygen abundances. No known galaxies with 12+log(O/H) < 7.9 (Z <
0.1 solar) have been detected in CO. Most of the star-forming galaxies with
higher (12+log(O/H) > 8.1) metallicities are detected at similar or higher I_CO
surface brightnesses. The data are consistent with a strong dependence of the
I_CO/M_H_2 = X_CO conversion factor on ambient metallicity. The strikingly low
upper limits on some metal-poor galaxies lead us to predict that the conversion
factor is non-linear, increasing sharply below approximately 1/10 of the solar
metallicity (12+log(O/H) < 7.9).Comment: 25 pages, 4 figures, 3 tables. Accepted for publication in AJ Tables
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