2,798 research outputs found
Mentorship Experiences of Women Leaders in Adventist Higher Education Institutions
There has been an increase in the rate at which women are being chosen to serve as university presidents at Adventist Higher Education institutions worldwide within the past few years. Notwithstanding that increase, the overall representation of women in that position is still proportionately low. To date, about 22 women have served since we first began operating higher education institutions in 1874. At present, about nine women are serving as presidents of AHEIs; the largest number to be serving at any one time since 1874 when AHEIs were established. Having so few women serving in these top-level positions does not provide opportunities for women to mentor and be mentored by other women. This paper examines the mentorship experiences of seven women who served or are currently serving as presidents of AHEIs prior to the their appointments as presidents. General findings reveal that the mentorship experiences played a critical role in the career advancement of these women leaders; though in the majority of the cases, men mentored these women. It is therefore highly recommended that strategic and deliberate mentorship opportunities be made for women-to-women, in an effort to ensure that more women leaders emerge to serve at AHEIs
Global Analysis of Fragmentation Functions for Eta Mesons
Fragmentation functions for eta mesons are extracted at next-to-leading order
accuracy of QCD in a global analysis of data taken in electron-positron
annihilation and proton-proton scattering experiments. The obtained
parametrization is in good agreement with all data sets analyzed and can be
utilized, for instance, in future studies of double-spin asymmetries for
single-inclusive eta production. The Lagrange multiplier technique is used to
estimate the uncertainties of the fragmentation functions and to assess the
role of the different data sets in constraining them.Comment: 11 pages, 8 figures, updated reference
Alternative cutworm control strategies : the effect on Missouri corn farmers of a cancellation of the pesticides chlordane and heptachlor
Cover title.Includes bibliographical references
Ionization Sources and Physical Conditions in the Diffuse Ionized Gas Halos of Four Edge-On Galaxies
Deep long-slit spectra of the diffuse ionized gas halos of the edge-on spiral
galaxies NGC 4302 and UGC 10288 are presented. These data, along with
previously presented data for NGC 5775 and NGC 891, are used to address the
issue of how DIG halos are energized. Composite photo-ionization/shock models
are generally better at explaining runs of line ratios in these galaxies than
photo-ionization models alone. Models of line ratios in NGC 5775 require a
greater contribution from shocks for filamentary regions than for
non-filamentary regions to explain the run of [OIII]/Halpha. In either case,
the [SII]/[NII] ratio is not well fit by the models. Composite models for UGC
10288 are successful at reproducing the run of [SII]/[NII] for all but the the
highest values of [NII]/Halpha; however, the run of [OIII]/Halpha vs.
[NII]/Halpha does not show any discernible trend, making it difficult to
determine whether or not shocks make a contribution.
We also examine whether the data can be explained simply by an increase in
temperature with z in a pure photo-ionization model. Runs of [SII]/Halpha,
[NII]/Halpha, and [SII]/[NII] in each of the four galaxies are consistent with
such an increase. However, the runs of [OIII]/Halpha vs. z in NGC 5775 and UGC
10288 require unusually high ionization fractions of O^{++} that can not be
explained without invoking a secondary ionization source or at the very least a
much higher temperature for the [OIII]-emitting component than for the [SII]-
and [NII]-emitting component. An increase in temperature with z is generally
more successful at explaining the [OIII]/Halpha run in NGC 891.Comment: 42 pages in aaspp4.sty format. This includes the 19 figures.
Reference added. Accepted for publication in Ap
Highly Ionized High-Velocity Clouds toward PKS 2155-304 and Markarian 509
To gain insight into four highly ionized high-velocity clouds (HVCs)
discovered by Sembach et al. (1999), we have analyzed data from the Hubble
Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) for the
PKS 2155-304 and Mrk 509 sight lines. We measure strong absorption in OVI and
column densities of multiple ionization stages of silicon (SiII/III/IV) and
carbon (CII/III/IV). We interpret this ionization pattern as a multiphase
medium that contains both collisionally ionized and photoionized gas. Toward
PKS 2155-304, for HVCs at -140 and -270 km/s, respectively, we measure
logN(OVI)=13.80+/-0.03 and log N(OVI)=13.56+/-0.06; from Lyman series
absorption, we find log N(HI)=16.37^(+0.22)_(-0.14) and 15.23^(+0.38)_(-0.22).
The presence of high-velocity OVI spread over a broad (100 km/s) profile,
together with large amounts of low-ionization species, is difficult to
reconcile with the low densities, n=5x10^(-6) cm^(-3), in the
collisional/photoionization models of Nicastro et al. (2002), although the HVCs
show a similar relation in N(SiIV)/N(CIV) versus N(CII)/N(CIV) as high-z
intergalactic clouds. Our results suggest that the high-velocity OVI in these
absorbers do not necessarily trace the WHIM, but instead may trace HVCs with
low total hydrogen column density. We propose that the broad high-velocity OVI
absorption arises from shock ionization, at bowshock interfaces produced from
infalling clumps of gas with velocity shear. The similar ratios of high ions
for HVC Complex C and these highly ionized HVCs suggest a common production
mechanism in the Galactic halo.Comment: 38 pages, including 10 figures. ApJ, 10 April, 2004. Replaced with
accepted versio
Safety Evaluation of Two Commercial Lithium-ion Batteries for Space Applications
Lithium-ion batteries have been used for applications on the Shuttle and Station for the past six years. A majority of the li-ion batteries flown are Commercial-off-the-shelf (COTS) varieties. The COTS batteries and cells were tested under nominal and abusive conditions for performance and safety characterization. Within the past six months two batteries have been certified for flight and use on the Space Station. The first one is a Hand Spring PDA battery that had a single prismatic li-ion cell and the second is an Iridium satellite phone that had a two-cell pack with prismatic li-ion cells
A comparative study of WASP-67b and HAT-P-38b from WFC3 data
Atmospheric temperature and planetary gravity are thought to be the main
parameters affecting cloud formation in giant exoplanet atmospheres. Recent
attempts to understand cloud formation have explored wide regions of the
equilibrium temperature-gravity parameter space. In this study, we instead
compare the case of two giant planets with nearly identical equilibrium
temperature ( ) and gravity (. During Cycle 23, we collected WFC3/G141
observations of the two planets, WASP-67 b and HAT-P-38 b. HAT-P-38 b, with
mass 0.42 M and radius 1.4 , exhibits a relatively
clear atmosphere with a clear detection of water. We refine the orbital period
of this planet with new observations, obtaining . WASP-67 b, with mass 0.27 M and radius 0.83
, shows a more muted water absorption feature than that of
HAT-P-38 b, indicating either a higher cloud deck in the atmosphere or a more
metal-rich composition. The difference in the spectra supports the hypothesis
that giant exoplanet atmospheres carry traces of their formation history.
Future observations in the visible and mid-infrared are needed to probe the
aerosol properties and constrain the evolutionary scenario of these planets.Comment: 16 pages, 17 figures, 8 tables, accepted for publication in The
Astronomical Journa
Imaging Fabry-Perot Spectroscopy of NGC 5775: Kinematics of the Diffuse Ionized Gas Halo
We present imaging Fabry-Perot observations of Halpha emission in the nearly
edge-on spiral galaxy NGC 5775. We have derived a rotation curve and a radial
density profile along the major axis by examining position-velocity (PV)
diagrams from the Fabry-Perot data cube as well as a CO 2-1 data cube from the
literature. PV diagrams constructed parallel to the major axis are used to
examine changes in azimuthal velocity as a function of height above the
midplane. The results of this analysis reveal the presence of a vertical
gradient in azimuthal velocity. The magnitude of this gradient is approximately
1 km/s/arcsec, or about 8 km/s/kpc, though a higher value of the gradient may
be appropriate in localized regions of the halo. The evidence for an azimuthal
velocity gradient is much stronger for the approaching half of the galaxy,
although earlier slit spectra are consistent with a gradient on both sides.
There is evidence for an outward radial redistribution of gas in the halo. The
form of the rotation curve may also change with height, but this is not
certain. We compare these results with those of an entirely ballistic model of
a disk-halo flow. The model predicts a vertical gradient in azimuthal velocity
which is shallower than the observed gradient, indicating that an additional
mechanism is required to further slow the rotation speeds in the halo.Comment: 18 pages, 18 figures. Uses emulateapj.cls. Accepted for publication
in Ap
Exclusive Production of Higgs Bosons in Hadron Colliders
We study the exclusive, double--diffractive production of the Standard Model
Higgs particle in hadronic collisions at LHC and FNAL (upgraded) energies. Such
a mechanism would provide an exceptionally clean signal for experimental
detection in which the usual penalty for triggering on the rare decays of the
Higgs could be avoided. In addition, because of the color singlet nature of the
hard interaction, factorization is expected to be preserved, allowing the
cross--section to be related to similar hard--diffractive events at HERA.
Starting from a Fock state expansion in perturbative QCD, we obtain an estimate
for the cross section in terms of the gluon structure functions squared of the
colliding hadrons. Unfortunately, our estimates yield a production rate well
below what is likely to be experimentally feasible.Comment: 17 pages, RevTeX file, four uufiled PostScript figures. UMPP #94-177.
(Revised version. Some mistakenly missing Feynman diagrams are now added.
Results do not change qualitatively. Paper reorganized.
Two real parton contributions to non-singlet kernels for exclusive QCD DGLAP evolution
Results for the two real parton differential distributions needed for
implementing a next-to-leading order (NLO) parton shower Monte Carlo are
presented. They are also integrated over the phase space in order to provide
solid numerical control of the MC codes and for the discussion of the
differences between the standard factorization and Monte Carlo
implementation at the level of inclusive NLO evolution kernels. Presented
results cover the class of non-singlet diagrams entering into NLO kernels. The
classic work of Curci-Furmanski-Pertonzio was used as a guide in the
calculations.Comment: 34 pages, 3 figure
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