404 research outputs found
Experiences of learning through collaborative evaluation from a masters programme in professional education
This paper presents findings from a collaborative evaluation project within a masters programme in professional education. The project aimed to increase knowledge of research methodologies and methods through authentic learning where participants worked in partnership with the tutor to evaluate the module which they were studying. The project processes, areas of the course evaluated and the data collection methods are outlined. The findings focus on key themes from evaluating the effectiveness of using a collaborative evaluation approach, including: enhanced student engagement; creativity of the collaborative evaluation approach; equality between the tutor and students; and enhanced research skills. Discussion focuses on the outcomes and effectiveness of the project and tutor reflections on adopting a collaborative approach. This paper highlights lessons from the project relevant to those interested in staff-student partnership approaches and those facilitating postgraduate learning and teaching programmes and educational research courses
Spectral Templates Optimal for Selecting Galaxies at z > 8 with JWST
The selection of high-redshift galaxies often involves spectral energy
distribution (SED) fitting to photometric data, an expectation for
contamination levels, and measurement of sample completeness -- all vetted
through comparison to spectroscopic redshift measurements of a sub-sample. The
first JWST data is now being taken over several extragalactic fields, to
different depths and across various areas, which will be ideal for the
discovery and classification of galaxies out to distances previously uncharted.
As spectroscopic redshift measurements for sources in this epoch will not be
initially available to compare with the first photometric measurements of z > 8
galaxies, robust photometric redshifts are of the utmost importance. Galaxies
at z > 8 are expected to have bluer rest-frame ultraviolet (UV) colors than
typically-used model SED templates, which could lead to catastrophic
photometric redshift failures. We use a combination of BPASS and Cloudy models
to create a supporting set of templates that match the predicted rest-UV colors
of z > 8 the simulated galaxies in a mock catalog (Yung et al. 2022), which
mimics expected field depths and areas of the Cosmic Evolution Early Release
Science Survey (CEERS: m ~ 28.6 over ~100 arcmin; Finkelstein
et al. 2022a, Bagley et al. 2022). We use EAZY to highlight the improvements in
redshift recovery with the inclusion of our new template set and suggest
criteria for selecting galaxies at 8 < z < 10 with JWST, providing an important
test case for observers venturing into this new era of astronomy.Comment: 14 pages, 10 figures, submitted to ApJ. SED templates published at:
ceers.github.io/LarsonSEDTemplate
CLEAR: High-Ionization [Ne V] 3426 Emission-line Galaxies at
We analyze a sample of 25 [Ne V] 3426 emission-line galaxies at
using Hubble Space Telescope/Wide Field Camera 3 G102 and G141
grism observations from the CANDELS Lyman- Emission at Reionization
(CLEAR) survey. [Ne V] emission probes extremely energetic photoionization
(97.11-126.21 eV), and is often attributed to energetic radiation from active
galactic nuclei (AGN), shocks from supernova, or an otherwise very hard
ionizing spectrum from the stellar continuum. In this work, we use [Ne V] in
conjunction with other rest-frame UV/optical emission lines ([O II]
3726,3729, [Ne III] 3869, H, [O III]
4959,5007, H+[N II] 6548,6583, [S II]
6716,6731), deep (2--7 Ms) X-ray observations (from Chandra),
and mid-infrared imaging (from Spitzer) to study the origin of this emission
and to place constraints on the nature of the ionizing engine. The majority of
the [Ne V]-detected galaxies have properties consistent with ionization from
AGN. However, for our [Ne V]-selected sample, the X-ray luminosities are
consistent with local () X-ray-selected Seyferts, but the [Ne V]
luminosities are more consistent with those from X-ray-selected QSOs.
The excess [Ne V] emission requires either reduced hard X-rays, or a 0.1
keV excess. We discuss possible origins of the apparent [Ne V] excess, which
could be related to the ``soft (X-ray) excess'' observed in some QSOs and
Seyferts, and/or be a consequence of a complex/anisotropic geometry for the
narrow line region, combined with absorption from a warm, relativistic wind
ejected from the accretion disk. We also consider implications for future
studies of extreme high-ionization systems in the epoch of reionization () with JWST.Comment: 17 pages + 5 (appendix), 7 figures + 2(appendix
The FENIKS Survey: Spectroscopic Confirmation of Massive Quiescent Galaxies at z ~ 3-5
The measured ages of massive, quiescent galaxies at imply that
massive galaxies quench as early as . While the number of
spectroscopic confirmations of quiescent galaxies at has increased over
the years, there are only a handful at . We report spectroscopic
redshifts of one secure () and two tentative (, )
massive () quiescent galaxies with 11 hours of
Keck/MOSFIRE -band observations. Our candidates were selected from the
FENIKS survey, which uses deep Gemini/Flamingos-2 imaging optimized
for increased sensitivity to the characteristic red colors of galaxies at with strong Balmer/4000 \AA\ breaks. The rest-frame and
colors of 3/4 quiescent candidates are consistent with Gyr old stellar
populations. This places these galaxies as the oldest objects at these
redshifts, and challenges the notion that quiescent galaxies at are all
recently-quenched, "post-starburst'' galaxies. Our spectroscopy shows that the
other quiescent-galaxy candidate is a broad-line AGN () with strong,
redshifted +[O III] emission with a velocity offset km/s,
indicative of a powerful outflow. The star-formation history of our highest
redshift candidate suggests that its progenitor was already in place by , reaching 10 by . These observations
reveal the limit of what is possible with deep near-infrared photometry and
targeted spectroscopy from the ground and demonstrate that secure spectroscopic
confirmation of quiescent galaxies at is only feasible with JWST.Comment: 20 pages, 11 figures, submitted to Ap
Using [Ne V]/[Ne III] to Understand the Nature of Extreme-Ionization Galaxies
Spectroscopic studies of extreme-ionization galaxies (EIGs) are critical to
our understanding of exotic systems throughout cosmic time. These EIGs exhibit
spectral features requiring >54.42 eV photons: the energy needed to fully
ionize helium into He2+ and emit He II recombination lines. They are likely key
contributors to reionization, and they can also probe exotic stellar
populations or accretion onto massive black holes. To facilitate the use of
EIGs as probes of high ionization, we focus on ratios constructed from strong
rest-frame UV/optical emission lines, specifically [O III] 5008, H-beta, [Ne
III] 3870, [O II] 3727,3729, and [Ne V] 3427. These lines probe the relative
intensity at energies of 35.12, 13.62, 40.96, 13.62 eV, and 97.12,
respectively, covering a wider range of ionization than traced by other common
rest-frame UV/optical techniques. We use ratios of these lines ([Ne V]/[Ne III]
= Ne53 and [Ne III]/[O II]), which are closely separated in wavelength, and
mitigates effects of dust attenuation and uncertainties in flux calibration. We
make predictions from photoionization models constructed from Cloudy that use a
broad range of stellar populations and black hole accretion models to explore
the sensitivity of these line ratios to changes in the ionizing spectrum. We
compare our models to observations from the Hubble Space Telescope and James
Webb Space Telescope of galaxies with strong high-ionization emission lines at
z ~ 0, z ~ 2, and z ~ 7. We show that the Ne53 ratio can separate galaxies with
ionization from 'normal' stellar populations from those with AGN and even
'exotic' Population III models. We introduce new selection methods to identify
galaxies with photoionization driven by Population III stars or
intermediate-mass black hole accretion disks that could be identified in
upcoming high-redshift spectroscopic surveys.Comment: 16 pages, 5 figures, 1 table. Accepted in Ap
Brain Biomarkers and Pre-Injury Cognition are Associated with Long-Term Cognitive Outcome in Children with Traumatic Brain Injury
BACKGROUND: Children with traumatic brain injury (TBI) are frequently at risk of long-term impairments of attention and executive functioning but these problems are difficult to predict. Although deficits have been reported to vary with injury severity, age at injury and sex, prognostication of outcome remains imperfect at a patient-specific level. The objective of this proof of principle study was to evaluate a variety of patient variables, along with six brain-specific and inflammatory serum protein biomarkers, as predictors of long-term cognitive outcome following paediatric TBI.
METHOD: Outcome was assessed in 23 patients via parent-rated questionnaires related to attention deficit hyperactivity disorder (ADHD) and executive functioning, using the Conners 3rd Edition Rating Scales (Conners-3) and Behaviour Rating Inventory of Executive Function (BRIEF) at a mean time since injury of 3.1 years. Partial least squares (PLS) analyses were performed to identify factors measured at the time of injury that were most closely associated with outcome on (1) the Conners-3 and (2) the Behavioural Regulation Index (BRI) and (3) Metacognition Index (MI) of the BRIEF.
RESULTS: Higher levels of neuron specific enolase (NSE) and lower levels of soluble neuron cell adhesion molecule (sNCAM) were associated with higher scores on the inattention, hyperactivity/impulsivity and executive functioning scales of the Conners-3, as well as working memory and initiate scales of the MI from the BRIEF. Higher levels of NSE only were associated with higher scores on the inhibit scale of the BRI.
CONCLUSIONS: NSE and sNCAM show promise as reliable, early predictors of long-term attention-related and executive functioning problems following paediatric TBI
JWST's TEMPLATES for Star Formation: The First Resolved Gas-Phase Metallicity Maps of Dust-Obscured Star-Forming Galaxies at 4
We present the first spatially resolved maps of gas-phase metallicity for
dust-obscured star-forming galaxies (DSFGs) at 4, from the JWST
TEMPLATES Early Release Science program, derived from NIRSpec integral field
unit spectroscopy of the H and [NII] emission lines. Empirically
derived literature optical line calibrations are used to determine that the
sources are highly metal rich, with both appearing to display regions of
supersolar metallicity, particularly in SPT2147-50. While we cannot rule out
shocks or AGN in these regions, we suggest that the two systems have already
undergone significant enrichment as a result of their extremely high
star-formation rates. Utilising ALMA rest-frame 380m continuum and
[CI](P-P) line maps we compare metallicity and gas-to-dust
ratio variations in the two galaxies, finding the two to be anticorrelated on
highly resolved spatial scales, consistent with various literature studies of
0 galaxies. The data are indicative of the enormous potential of
JWST to probe the enrichment of the interstellar medium on kpc scales in
extremely dust-obscured systems at 4 and beyond.Comment: 12 pages, 5 figures, submitted to Ap
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