14,235 research outputs found
Recommended from our members
Attack and Parry: An Examination of Gubernatorial Rhetoric and Agenda Setting for Higher Education in Texas, 2000-2015
This paper applies political discourse analysis to an examination of gubernatorial rhetoric and agenda setting around higher education in Texas during Governor Rick Perry’s leadership, from 2000-2015. The authors analyzed 28 gubernatorial speeches using manifest content analysis in STATA and qualitative coding via pattern matching in Atlas.ti. Findings reveal that Governor Rick Perry: 1) framed the higher education agenda around reform strategies to increase accountability, efficiency, and affordability; 2) functioned as both an agenda setter and policy entrepreneur; and 3) primed constituents to support his agenda by positioning higher education as a workforce development mechanism and invoking Texas’s tradition of leadership and competitiveness.Educatio
Coronal Electron Confinement by Double Layers
In observations of flare-heated electrons in the solar corona, a longstanding
problem is the unexplained prolonged lifetime of the electrons compared to
their transit time across the source. This suggests confinement. Recent
particle-in-cell (PIC) simulations, which explored the transport of
pre-accelerated hot electrons through ambient cold plasma, showed that the
formation of a highly localized electrostatic potential drop, in the form of a
double layer (DL), significantly inhibited the transport of hot electrons (T.C.
Li, J.F. Drake, and M. Swisdak, 2012, ApJ, 757, 20). The effectiveness of
confinement by a DL is linked to the strength of the DL as defined by its
potential drop. In this work, we investigate the scaling of the DL strength
with the hot electron temperature by PIC simulations, and find a linear
scaling. We demonstrate that the strength is limited by the formation of
parallel shocks. Based on this, we analytically determine the maximum DL
strength, and find also a linear scaling with the hot electron temperature. The
DL strength obtained from the analytic calculation is comparable to that from
the simulations. At the maximum strength, the DL is capable of confining a
significant fraction of hot electrons in the source
Chemical analysis of giant stars in the young open cluster NGC 3114
Context: Open clusters are very useful targets for examining possible trends
in galactocentric distance and age, especially when young and old open clusters
are compared. Aims: We carried out a detailed spectroscopic analysis to derive
the chemical composition of seven red giants in the young open cluster NGC
3114. Abundances of C, N, O, Li, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce,
and Nd were obtained, as well as the carbon isotopic ratio. Methods: The
atmospheric parameters of the studied stars and their chemical abundances were
determined using high-resolution optical spectroscopy. We employed the
local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral
analysis code MOOG. The abundances of the light elements were derived using the
spectral synthesis technique. Results: We found that NGC 3114 has a mean
metallicity of [Fe/H] = -0.01+/-0.03. The isochrone fit yielded a turn-off mass
of 4.2 Msun. The [N/C] ratio is in good agreement with the models predicted by
first dredge-up. We found that two stars, HD 87479 and HD 304864, have high
rotational velocities of 15.0 km/s and 11.0 km/s; HD 87526 is a halo star and
is not a member of NGC 3114. Conclusions: The carbon and nitrogen abundance in
NGC 3114 agree with the field and cluster giants. The oxygen abundance in NGC
3114 is lower compared to the field giants. The [O/Fe] ratio is similar to the
giants in young clusters. We detected sodium enrichment in the analyzed cluster
giants. As far as the other elements are concerned, their [X/Fe] ratios follow
the same trend seen in giants with the same metallicity.Comment: 17 pages, 9 figures, 10 tables; accepted for publication in A&
X-Ray Wakes in Abell 160
`Wakes' of X-ray emission have now been detected trailing behind a few (at
least seven) elliptical galaxies in clusters. To quantify how widespread this
phenomenon is, and what its nature might be, we have obtained a deep (70 ksec)
X-ray image of the poor cluster Abell 160 using the ROSAT HRI. Combining the
X-ray data with optical positions of confirmed cluster members, and applying a
statistic designed to search for wake-like excesses, we confirm that this
phenomenon is observed in galaxies in this cluster. The probability that the
detections arise from chance is less than 0.0038. Further, the wakes are not
randomly distributed in direction, but are preferentially oriented pointing
away from the cluster centre. This arrangement can be explained by a simple
model in which wakes arise from the stripping of their host galaxies'
interstellar media due to ram pressure against the intracluster medium through
which they travel.Comment: 7 pages, 7 figures, accepted for publication in MNRA
- …