60 research outputs found
The Cool ISM in Elliptical Galaxies. II. Gas Content in the Volume - Limited Sample and Results from the Combined Elliptical and Lenticular Surveys
We report new observations of atomic and molecular gas in a volume limited
sample of elliptical galaxies. Combining the elliptical sample with an earlier
and similar lenticular one, we show that cool gas detection rates are very
similar among low luminosity E and SO galaxies but are much higher among
luminous S0s. Using the combined sample we revisit the correlation between cool
gas mass and blue luminosity which emerged from our lenticular survey, finding
strong support for previous claims that the molecular gas in ellipticals and
lenticulars has different origins. Unexpectedly, however, and contrary to
earlier claims, the same is not true for atomic gas. We speculate that both the
AGN feedback and merger paradigms might offer explanations for differences in
detection rates, and might also point towards an understanding of why the two
gas phases could follow different evolutionary paths in Es and S0s. Finally we
present a new and puzzling discovery concerning the global mix of atomic and
molecular gas in early type galaxies. Atomic gas comprises a greater fraction
of the cool ISM in more gas rich galaxies, a trend which can be plausibly
explained. The puzzle is that galaxies tend to cluster around
molecular-to-atomic gas mass ratios near either 0.05 or 0.5.Comment: 37 pages, including 4 tables and 12 figures. Accepted for publication
in the Astrophysical Journa
The Cool ISM in S0 Galaxies. I. A Survey of Molecular Gas
Lenticular galaxies remain remarkably mysterious as a class. Observations to
date have not led to any broad consensus about their origins, properties and
evolution, though they are often thought to have formed in one big burst of
star formation early in the history of the Universe, and to have evolved
relatively passively since then. In that picture, current theory predicts that
stellar evolution returns substantial quantities of gas to the interstellar
medium; most is ejected from the galaxy, but significant amounts of cool gas
might be retained. Past searches for that material, though, have provided
unclear results. We present results from a survey of molecular gas in a
volume-limited sample of field S0 galaxies, selected from the Nearby Galaxies
Catalog. CO emission is detected from 78 percent of the sample galaxies. We
find that the molecular gas is almost always located inside the central few
kiloparses of a lenticular galaxy, meaning that in general it is more centrally
concentrated than in spirals. We combine our data with HI observations from the
literature to determine the total masses of cool and cold gas. Curiously, we
find that, across a wide range of luminosity, the most gas rich galaxies have
about 10 percent of the total amount of gas ever returned by their stars. That
result is difficult to understand within the context of either monolithic or
hierarchical models of evolution of the interstellar medium.Comment: 26 pages of text, 15 pages of tables, 10 figures. Accepted for
publication in the Astrophysical Journa
The Cool ISM in Elliptical Galaxies. I. A Survey of Molecular Gas
We present preliminary results from a survey of CO emission from members of a
volume-limited sample of non-cluster elliptical galaxies. Our intent is to
compare the gas properties of these ellipticals to a sample of lenticulars
selected using similar criteria. The data, although still sparse, suggest that
the cool gas in ellipticals shows the same puzzling upper mass cutoff found in
the lenticular galaxies. We find, however, significantly lower detection rates
and possibly much lower H2/HI mass ratios in the ellipticals. The detection
rate is higher among the lower-mass galaxies, as has been found previously.
This seems puzzling given that the deeper potential wells of the larger
galaxies ought to make gas retention easier, but perhaps that effect is
overwhelmed by feedback from the central suppermassive black hole. As we have
observed ~40 percent of our sample, the conclusions are necessarily tentative
at this time.Comment: Accepted for publication in the Astrophysical Journa
Angiopoietin-1 alters microvascular permeability coefficients in vivo via modification of endothelial glycocalyx
Outer space technopolitics and postcolonial modernity in Kazakhstan
This is the final version. Available on open access from Routledge via the DOI in this recordThis article examines the role of outer space technopolitics in post-Soviet
Kazakhstan. It explores how outer space, the technological artefact of global
relevance, works as a postcolonial fetish of modernity that is called upon to produce
what it represents, i.e. the reality of a technologically advanced Kazakh nation. The
article shows that in its project of becoming a spacefaring nation the country reiterates
major incentives that have motivated nuclear and space programme development in
the postcolonial context of the Global South. The article explores how collaboration
with Russia allows Kazakhstan to claim its share in the Soviet space legacy rather
than to distance itself from it. It then traces the rise of a new internationalism in the
Kazakhstani space programme outside the post-Soviet context. The article contributes
to the debate on postcolonial techonopolitics and shows how outer space has been
used to enhance the conventional domain of postcolonial national ideologies –
nativism and tradition – with technology and science. Finally, the article depicts how
the growing resistance to the space programme among Kazakh civil society groups
reveals a close association of the environmental agenda with an “eco-nationalism”
permeated by a profoundly anti-imperial and, ultimately, antiauthoritarian political
discourse
Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures
Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
Using Authentic Data from NSF’s Ocean Observatories Initiative in Undergraduate Teaching: An Invitation
There are many benefits to using real data in undergraduate science education, including building analytical and problem-solving skills and visualizing concepts through real-world examples. The Ocean Observatories Initiative (OOI) provides a unique source of continuous, long-term oceanographic data from multiple locations in the world ocean. Each of these arrays hosts a suite of co-located instruments that measure physical, chemical, geological, and biological properties. Existing educational resources derived from OOI data can be leveraged for undergraduate teaching activities in and beyond the classroom. We provide example applications of the use of OOI resources in lesson plans and in research experiences for undergraduates. There are also abundant opportunities for new resources to be developed by the community. Our goal is to guide educators in determining appropriate OOI data sets and applications for their own needs
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