339 research outputs found
Early JWST imaging reveals strong optical and NIR color gradients in galaxies at driven mostly by dust
Recent studies have shown that galaxies at cosmic noon are redder in the
center and bluer in the outskirts, mirroring results in the local universe.
These color gradients could be caused by either gradients in the stellar age or
dust opacity; however, distinguishing between these two causes is impossible
with rest-frame optical photometry alone. Here we investigate the underlying
causes of the gradients from spatially-resolved rest-frame vs.
color-color diagrams, measured from early observations with the James Webb
Space Telescope. We use NIRCam photometry from the
CEERS survey of a sample of 54 galaxies with at redshifts
selected from the 3D-HST catalog. We model the light profiles in
the F115W, F200W and F356W NIRCam bands using \texttt{imcascade}, a Bayesian
implementation of the Multi-Gaussian expansion (MGE) technique which flexibly
represents galaxy profiles using a series of Gaussians. We construct resolved
rest-frame and color profiles. The majority of star-forming
galaxies have negative gradients (i.e. redder in the center, bluer in the
outskirts) in both and colors consistent with radially decreasing
dust attenuation. A smaller population (roughly 15\%) of star-forming galaxies
have positive but negative gradients implying centrally
concentrated star-formation. For quiescent galaxies we find a diversity of UVJ
color profiles, with roughly one-third showing star-formation in their center.
This study showcases the potential of JWST to study the resolved stellar
populations of galaxies at cosmic noon.Comment: Updated to match published version, new Figure 5 and some text
change
Rest-frame near-infrared sizes of galaxies at cosmic noon: objects in JWST's mirror are smaller than they appeared
Galaxy sizes and their evolution over cosmic time have been studied for
decades and serve as key tests of galaxy formation models. However, at
these studies have been limited by a lack of deep, high-resolution
rest-frame infrared imaging that accurately traces galaxy stellar mass
distributions. Here, we leverage the new capabilities of the James Webb Space
Telescope to measure the 4.4m sizes of galaxies with
and from public CEERS
imaging in the EGS deep field. We compare the sizes of galaxies measured from
NIRCam imaging at 4.4m (m) with sizes
measured at m (A). We find that, on
average, galaxy half-light radii are % smaller at 4.4m than
1.5m in this sample. This size difference is markedly stronger at higher
stellar masses and redder rest-frame colors: galaxies with have 4.4m sizes that are % smaller
than their 1.5m sizes. Our results indicate that galaxy mass profiles are
significantly more compact than their rest-frame optical light profiles at
cosmic noon, and demonstrate that spatial variations in age and attenuation are
important, particularly for massive galaxies. The trend that we find here
impacts our understanding of the size growth and evolution of galaxies, and
suggests that previous studies based on rest-frame optical light may not have
captured the mass-weighted structural evolution of galaxies. This paper
represents a first step towards a new understanding of the morphologies of
early massive galaxies enabled by JWST's infrared window into the distant
universe.Comment: Accepted to ApJL. 10 pages, 4 figures, 1 table with full size catalog
in F150W and F444
Dual Action of miR-125b As a Tumor Suppressor and OncomiR-22 Promotes Prostate Cancer Tumorigenesis
MicroRNAs (miRs) are a novel class of small RNA molecules, the dysregulation of which can contribute to cancer. A combinatorial approach was used to identify miRs that promote prostate cancer progression in a unique set of prostate cancer cell lines, which originate from the parental p69 cell line and extend to a highly tumorigenic/metastatic M12 subline. Together, these cell lines are thought to mimic prostate cancer progression in vivo. Previous network analysis and miR arrays suggested that the loss of hsa-miR-125b together with the overexpression of hsa-miR-22 could contribute to prostate tumorigenesis. The dysregulation of these two miRs was confirmed in human prostate tumor samples as compared to adjacent benign glandular epithelium collected through laser capture microdissection from radical prostatectomies. In fact, alterations in hsa-miR-125b expression appeared to be an early event in tumorigenesis. Reverse phase microarray proteomic analysis revealed ErbB2/3 and downstream members of the PI3K/AKT and MAPK/ERK pathways as well as PTEN to be protein targets differentially expressed in the M12 tumor cell compared to its parental p69 cell. Relevant luciferase+3’-UTR expression studies confirmed a direct interaction between hsa-miR-125b and ErbB2 and between hsa-miR-22 and PTEN. Restoration of hsa-miR-125b or inhibition of hsa-miR-22 expression via an antagomiR resulted in an alteration of M12 tumor cell behavior in vitro. Thus, the dual action of hsa-miR-125b as a tumor suppressor and hsa-miR-22 as an oncomiR contributed to prostate tumorigenesis by modulations in PI3K/AKT and MAPK/ERK signaling pathways, key pathways known to influence prostate cancer progression
Quantifying the Effects of Known Unknowns on Inferred High-redshift Galaxy Properties: Burstiness, the IMF, and Nebular Physics
The era of the James Webb Space Telescope ushers stellar populations models
into uncharted territories, particularly at the high-redshift frontier. In a
companion paper, we apply the \texttt{Prospector} Bayesian framework to jointly
infer galaxy redshifts and stellar populations properties from broad-band
photometry as part of the UNCOVER survey. Here we present a comprehensive error
budget in spectral energy distribution (SED) modeling. Using a
sample, we quantify the systematic shifts stemming from various model choices
in inferred stellar mass, star formation rate (SFR), and age. These choices
encompass different timescales for changes in the star formation history (SFH),
non-universal stellar initial mass functions (IMF), and the inclusion of
variable nebular abundances, gas density and ionizing photon budget. We find
that the IMF exerts the strongest influence on the inferred properties: the
systematic uncertainties can be as much as 1 dex, 2--5 times larger than the
formal reported uncertainties in mass and SFR; and importantly, exceed the
scatter seen when using different SED fitting codes. This means that a common
practice in the literature of assessing uncertainties in SED-fitting processes
by comparing multiple codes is substantively underestimating the true
systematic uncertainty. Highly stochastic SFHs change the inferred SFH by much
larger than the formal uncertainties, and introduce dex systematics
in SFR and dex systematics in average age. Finally, employing a
flexible nebular emission model causes dex systematic increase in
mass, comparable to the formal uncertainty. This paper constitutes one of the
initial steps toward a complete uncertainty estimate in SED modeling.Comment: Submitted to ApJ. 18 pages, 8 figures, 2 table
"Now he walks and walks, as if he didn't have a home where he could eat": food, healing, and hunger in Quechua narratives of madness
In the Quechua-speaking peasant communities of southern Peru, mental disorder is understood less as individualized pathology and more as a disturbance in family and social relationships. For many Andeans, food and feeding are ontologically fundamental to such relationships. This paper uses data from interviews and participant observation in a rural province of Cuzco to explore the significance of food and hunger in local discussions of madness. Carers’ narratives, explanatory models, and theories of healing all draw heavily from idioms of food sharing and consumption in making sense of affliction, and these concepts structure understandings of madness that differ significantly from those assumed by formal mental health services. Greater awareness of the salience of these themes could strengthen the input of psychiatric and psychological care with this population and enhance knowledge of the alternative treatments that they use. Moreover, this case provides lessons for the global mental health movement on the importance of openness to the ways in which indigenous cultures may construct health, madness, and sociality. Such local meanings should be considered by mental health workers delivering services in order to provide care that can adjust to the alternative ontologies of sufferers and carers
Two Remarkably Luminous Galaxy Candidates at Revealed by JWST
The first few hundred Myrs at mark the last major uncharted epoch in
the history of the Universe, where only a single galaxy (GNz11 at )
is currently spectroscopically confirmed. Here we present a search for luminous
galaxies with /NIRCam photometry spanning m and
covering 49 arcmin from the public Early Release Science programs
(CEERS and GLASS). Our most secure candidates are two
systems: GLASS-z13 and GLASS-z11. These galaxies display abrupt
mag breaks in their spectral energy distributions, consistent with complete
absorption of flux bluewards of Lyman- that is redshifted to
and . Lower redshift interlopers such as dusty
quiescent galaxies with strong Balmer breaks would be comfortably detected at
in multiple bands where instead we find no flux. From SED modeling
we infer that these galaxies have already built up solar masses in
stars over the Myrs after the Big Bang. The brightness of
these sources enable morphological constraints. Tantalizingly, GLASS-z11 shows
a clearly extended exponential light profile, potentially consistent with a
disk galaxy of kpc. These sources, if confirmed, join
GNz11 in defying number density forecasts for luminous galaxies based on
Schechter UV luminosity functions, which require a survey area
larger than we have studied here to find such luminous sources at such high
redshifts. They extend evidence from lower redshifts for little or no evolution
in the bright end of the UV luminosity function into the cosmic dawn epoch,
with implications for just how early these galaxies began forming. This, in
turn, suggests that future deep observations may identify relatively
bright galaxies to much earlier epochs than might have been anticipated.Comment: Submitted to ApJL. Figs. 1 and 2 summarize the candidates, Fig. 3
places the brightness of these systems in context, Fig. 4 shows the
morphology, Fig. 5 explores implications for the UVLF. Comments warmly
welcome
JWST reveals a population of ultra-red, flattened disk galaxies at 2<z<6 previously missed by HST
With just a month of data, JWST is already transforming our view of the
Universe, revealing and resolving starlight in unprecedented populations of
galaxies. Although ``HST-dark" galaxies have previously been detected at long
wavelengths, these observations generally suffer from a lack of spatial
resolution which limits our ability to characterize their sizes and
morphologies. Here we report on a first view of starlight from a subset of the
HST-dark population that are bright with JWST/NIRCam (4.4m<24.5mag) and
very faint or even invisible with HST (1.6m). In this Letter we focus
on a dramatic and unanticipated population of physically extended galaxies
(0.17''). These 12 galaxies have photometric redshifts , high
stellar masses , and significant
dust-attenuated star formation. Surprisingly, the galaxies have elongated
projected axis ratios at 4.4m, suggesting that the population is
disk-dominated or prolate. Most of the galaxies appear red at all radii,
suggesting significant dust attenuation throughout. We refer to these red,
disky, HST-dark galaxies as Ultra-red Flattened Objects (UFOs). With
(F444W)~kpc, the galaxies are similar in size to compact massive
galaxies at and the cores of massive galaxies and S0s at . The
stellar masses, sizes, and morphologies of the sample suggest that some could
be progenitors of lenticular or fast-rotating galaxies in the local Universe.
The existence of this population suggests that our previous censuses of the
universe may have missed massive, dusty edge-on disks, in addition to
dust-obscured starbursts
The Benefits and Burdens of Pediatric Palliative Care and End-of-Life Research: A Systematic Review
Objective: The aim of this study is to report the benefits and burdens of palliative research participation on children, siblings, parents, clinicians, and researchers.
Background: Pediatric palliative care requires research to mature the science and improve interventions. A tension exists between the desire to enhance palliative and end-of-life care for children and their families and the need to protect these potentially vulnerable populations from untoward burdens.
Methods: Systematic review followed PRISMA guidelines with prepared protocol registered as PROSPERO #CRD42018087304. MEDLINE, CINAHL, PsycINFO, EMBASE, Scopus, and The Cochrane Library were searched (2000–2017). English-language studies depicting the benefits or burdens of palliative care or end-of-life research participation on either pediatric patients and/or their family members, clinicians, or study teams were eligible for inclusion. Study quality was appraised using the Mixed Methods Appraisal Tool (MMAT).
Results: Twenty-four studies met final inclusion criteria. The benefit or burden of palliative care research participation was reported for the child in 6 papers; siblings in 2; parents in 19; clinicians in 3; and researchers in 5 papers. Benefits were more heavily emphasized by patients and family members, whereas burdens were more prominently emphasized by researchers and clinicians. No paper utilized a validated benefit/burden scale.
Discussion: The lack of published exploration into the benefits and burdens of those asked to take part in pediatric palliative care research and those conducting the research is striking. There is a need for implementation of a validated benefit/burden instrument or interview measure as part of pediatric palliative and end-of-life research design and reporting
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