294 research outputs found
How It\u27s Done : The Role of Mentoring and Advice in Preparing the Next Generation of Historically Black College and University Presidents
The college and university presidency is one of the most coveted positions in academe. Due to the projected retirements of current Historically Black College and University (HBCU) presidents, the researchers interviewed 21 current presidents, institutional board members, and presidential search firm personnel to explore what current HBCU leadership identifies as important mentoring/mentee practices, mentoring/mentee opportunities, and professional advice for HBCU presidential aspirants to consider. The findings, based on the coding and analysis of semi-structured qualitative interviews, revealed that self-awareness, focusing on the essential aspects of the job and not merely the perks, openness to being mentored and willingness to shadow a successful leader, experience in serving in various administrative capacities, participating in professional leadership development activities, earning of a terminal degree, displaying humility, understanding academic politics, and learning how to present oneself as an executive is important in the preparation of a leader of an HBCU
Historically Black Colleges and Universities: Recent Trends (2007)
The nation’s historically black colleges and universities (HBCUs) are diverse. Although we discuss them as a category based on their historical racial makeup, these institutions are in fact quite different from one another. According to the government’s definition, black colleges are bound together by the fact that they were established prior to 1964 (the year of the Civil Rights Act) with the express purpose of educating African Americans. These institutions, of which there are 103, are public, private, large, small, religious, nonsectarian, selective, and open-enrolling. They educate 300,000 students and employ over 14,000 faculty members.1 Some black colleges are thriving, others are barely making ends meet, and many fall in between. Regardless, most of them are providing a much needed education to African American students (and many others)
The diverse chemistry of protoplanetary disks as revealed by JWST
Early results from the JWST-MIRI guaranteed time programs on protostars
(JOYS) and disks (MINDS) are presented. Thanks to the increased sensitivity,
spectral and spatial resolution of the MIRI spectrometer, the chemical
inventory of the planet-forming zones in disks can be investigated with
unprecedented detail across stellar mass range and age. Here data are presented
for five disks, four around low-mass stars and one around a very young
high-mass star. The mid-infrared spectra show some similarities but also
significant diversity: some sources are rich in CO2, others in H2O or C2H2. In
one disk around a very low-mass star, booming C2H2 emission provides evidence
for a ``soot'' line at which carbon grains are eroded and sublimated, leading
to a rich hydrocarbon chemistry in which even di-acetylene (C4H2) and benzene
(C6H6) are detected (Tabone et al. 2023). Together, the data point to an active
inner disk gas-phase chemistry that is closely linked to the physical structure
(temperature, snowlines, presence of cavities and dust traps) of the entire
disk and which may result in varying CO2/H2O abundances and high C/O ratios >1
in some cases. Ultimately, this diversity in disk chemistry will also be
reflected in the diversity of the chemical composition of exoplanets.Comment: 17 pages, 8 figures. Author's version of paper submitted to Faraday
Discussions January 18 2023, Accepted March 16 202
JWST MIRI/MRS in-flight absolute flux calibration and tailored fringe correction for unresolved sources
Context. The Medium Resolution Spectrometer (MRS) is one of the four observing modes of JWST/MIRI. Using JWST in-flight data of unresolved (point) sources, we can derive the MRS absolute spectral response function (ASRF) starting from raw data. Spectral fringing, caused by coherent reflections inside the detector arrays, plays a critical role in the derivation and interpretation of the MRS ASRF. The fringe corrections implemented in the current pipeline are not optimal for non-extended sources, and a high density of molecular features particularly inhibits an accurate correction. Aims. In this paper, we present an alternative way to calibrate the MIRI/MRS data. Firstly, we derive a fringe correction that accounts for the dependence of the fringe properties on the MIRI/MRS pupil illumination and detector pixel sampling of the point spread function. Secondly, we derive the MRS ASRF using an absolute flux calibrator observed across the full 5- 28 \ub5m wavelength range of the MRS. Thirdly, we apply the new ASRF to the spectrum of a G dwarf and compare it with the output of the JWST/MIRI default data reduction pipeline. Finally, we examine the impact of the different fringe corrections on the detectability of molecular features in the G dwarf and K giant. Methods. The absolute flux calibrator HD 163466 (A-star) was used to derive tailored point source fringe flats at each of the default dither locations of the MRS. The fringe-corrected point source integrated spectrum of HD 163466 was used to derive the MRS ASRF using a theoretical model for the stellar continuum. A cross-correlation was run to quantify the uncertainty on the detection of CO, SiO, and OH in the K giant and CO in the G dwarf for different fringe corrections. Results. The point-source-tailored fringe correction and ASRF are found to perform at the same level as the current corrections, beating down the fringe contrast to the sub-percent level in the G dwarf in the longer wavelengths, whilst mitigating the alteration of real molecular features. The same tailored solutions can be applied to other MRS unresolved targets. Target acquisition is required to ensure the pointing is accurate enough to apply this method. A pointing repeatability issue in the MRS limits the effectiveness of the tailored fringe flats is at short wavelengths. Finally, resulting spectra require no scaling to make the sub-bands match, and a dichroic spectral leak at 12.2 \ub5m is removed
Nuclear high-ionisation outflow in the Compton-thick AGN NGC6552 as seen by the JWST mid-infrared instrument
During the commissioning of the James Webb Space Telescope (JWST), the
mid-infrared instrument (MIRI) observed NGC6552 with the MIRI Imager and the
medium-resolution spectrograph (MRS). NGC6552 is an active galactic nucleus
(AGN) at redshift 0.0266 classified as a Seyfert 2 nucleus in the optical, and
Compton-thick AGN in X-rays. This work exemplifies and demonstrates the MRS
capabilities to study the mid-infrared (mid-IR) spectra and characterize the
physical conditions and kinematics of the ionized and molecular gas in the
nuclear regions of nearby galaxies. We obtained the nuclear, circumnuclear, and
central mid-IR spectra of NGC6552. They provide the first clear observational
evidence for a nuclear outflow in NGC6552. The outflow contributes to 677%
of the total line flux independent of the ionization potential (27 to 187 eV)
and critical densities (10 to 410 cm), showing an
average blue-shifted peak velocity of -12745 kms and an outflow
maximal velocity of 69880 kms. Since the mid-IR photons penetrate
dusty regions as efficiently as X-ray keV photons, we interpret these results
as the evidence for a highly ionized, non-stratified, AGN-powered, and fast
outflowing gas in a low density environment (few 10 cm) located
very close (<0.2kpc) to the Compton-thick AGN. Nine pure rotational molecular
Hydrogen lines are detected and spectrally resolved, and exhibit symmetric
Gaussian profiles, consistent with the galactic rotation, and with no evidence
of outflowing H material. We detect a warm H mass of
in the central region (1.8 kpc in diameter) of
the galaxy, with almost 30% of that mass in the circum-nuclear region. Line
ratios confirm that NGC6552 has a Seyfert nucleus with a black hole mass
estimated in the range of 0.6 to 6 million solar masses.Comment: 13 pages, 5 figures, 5 tables, accepted in A&
MINDS. JWST-MIRI Reveals a Dynamic Gas-Rich Inner Disk Inside the Cavity of SY Cha
SY Cha is a T Tauri star surrounded by a protoplanetary disk with a large
cavity seen in the millimeter continuum but has the spectral energy
distribution (SED) of a full disk. Here we report the first results from
JWST-MIRI Medium Resolution Spectrometer (MRS) observations taken as part of
the MIRI mid-INfrared Disk Survey (MINDS) GTO Program. The much improved
resolution and sensitivity of MIRI-MRS compared to Spitzer enables a robust
analysis of the previously detected H2O, CO, HCN, and CO2 emission as well as a
marginal detection of C2H2. We also report the first robust detection of
mid-infrared OH and ro-vibrational CO emission in this source. The derived
molecular column densities reveal the inner disk of SY Cha to be rich in both
oxygen and carbon bearing molecules. This is in contrast to PDS 70, another
protoplanetary disk with a large cavity observed with JWST, which displays much
weaker line emission. In the SY Cha disk, the continuum, and potentially the
line, flux varies substantially between the new JWST observations and archival
Spitzer observations, indicative of a highly dynamic inner disk.Comment: 19 pages, 10 figures, 5 tables, accepted for publication in Ap
Historical Analysis: Tracking, Problematizing, and Reterritorializing Achievement and the Achievement Gap
For more than a century, state and federal governments and organizations have used different measures to determine if students and groups of students have achieved in a particular subject or grade level. While the construct of achievement is applied irrespective of student differences, this equal application turns out to be anything but equitable. In this chapter, we work to understand the way achievement plays out for Black students by deconstructing how the word achievement works. In doing so, we track the history of education, testing, and curriculum as it has been applied to Black youth and youth of color
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