54 research outputs found
Duoethnography as Transformative Praxis: Conversations about Nourishment and Coercion in the COVID-Era Academy
This article introduces the feminist praxis of duoethnography as a way to examine the COVID era. As a group of diverse, junior, midcareer, and senior feminist scholars, we developed a methodology to critically reflect on our positions in our institutions and social worlds. As a method, duoethnography emphasizes the dialogical intimacy that can form through anthropological work. While autoethnography draws on individual daily lives to make sense of sociopolitical dynamics, duoethnography emphasizes the relational character of research across people and practices. Taking the relational aspects of knowledge production seriously, we conceptualized this praxis as a transformative method for facilitating radical empathy, mobilizing our collective voice, and merging together our partial truths. As collective authors, interviewers, and interlocutors of this article, the anonymity of duoethnography allows us to vocalize details of the experience of living through COVID19 that we could not have safely spoken about publicly or on our ow
Star Formation History of the Hubble Ultra Deep Field: Comparison with the HDFN
We use the NICMOS Treasury and ACS HUDF images to measure the extinction
corrected star formation history for 4681 galaxies in the region common to both
images utilizing the star formation rate distribution function and other
techniques similar to those employed with the NICMOS and WFPC2 images in the
HDFN. Unlike the HDFN the NICMOS region of the HUDF appears to lack highly
luminous and high star formation rate galaxies at redshifts beyond 3. The HUDF
provides a region that is completely uncorrelated to the HDFN and therefore
provides and independent measure of the star formation history of the universe.
The combined HUDF and HDFN star formation rates show an average star formation
rate of 0.2 solar masses per yer per cubic megaparsec. The average SFR of the
combined fields at z = 1-3 is 0.29 solar masses per year per cubic megaparsec
while the average at z = 4-6 is 1.2 solar masses per year per cubic megaparsec.
The SFRs at all redshifts are within 3 sigma of the average over all redshifts.Comment: Accepted for publication in the Astrophysical Journa
z~7 galaxy candidates from NICMOS observations over the HDF South and the CDF-S and HDF-N GOODS fields
We use ~88 arcmin**2 of deep (>~26.5 mag at 5 sigma) NICMOS data over the two
GOODS fields and the HDF South to conduct a search for bright z>~7 galaxy
candidates. This search takes advantage of an efficient preselection over 58
arcmin**2 of NICMOS H-band data where only plausible z>~7 candidates are
followed up with NICMOS J-band observations. ~248 arcmin**2 of deep
ground-based near-infrared data (>~25.5 mag, 5 sigma) is also considered in the
search. In total, we report 15 z-dropout candidates over this area -- 7 of
which are new to these search fields. Two possible z~9 J-dropout candidates are
also found, but seem unlikely to correspond to z~9 galaxies. The present z~9
search is used to set upper limits on the prevalence of such sources. Rigorous
testing is undertaken to establish the level of contamination of our selections
by photometric scatter, low mass stars, supernovae (SNe), and spurious sources.
The estimated contamination rate of our z~7 selection is ~24%. Through careful
simulations, the effective volume available to our z>~7 selections is estimated
and used to establish constraints on the volume density of luminous (L*(z=3),
or -21 mag) galaxies from these searches. We find that the volume density of
luminous star-forming galaxies at z~7 is 13_{-5}^{+8}x lower than at z~4 and
>25x lower (1 sigma) at z~9 than at z~4. This is the most stringent constraint
yet available on the volume density of >~L* galaxies at z~9. The present
wide-area, multi-field search limits cosmic variance to <20%. The evolution we
find at the bright end of the UV LF is similar to that found from recent Subaru
Suprime-Cam, HAWK-I or ERS WFC3/IR searches. The present paper also includes a
complete summary of our final z~7 z-dropout sample (18 candidates) identified
from all NICMOS observations to date (over the two GOODS fields, the HUDF,
galaxy clusters).Comment: 13 pages, 6 figures, 6 tables, accepted for publication in the
Astrophysical Journal, replaced to match accepted version, see
http://firstgalaxies.org/astronomers-area/ for a link to a complete reduction
of the NICMOS observations over the two GOODS field
The NICMOS Ultra Deep Field: Observations, Data Reduction, and Galaxy Photometry
This paper describes the observations and data reduction techniques for the
version 2.0 images and catalog of the NICMOS Ultra Deep Field Treasury program.
All sources discussed in this paper are based on detections in the combined
NICMOS F110W and F160W bands only. The NICMOS images are drizzled to 0.09 arc
second pixels and aligned to the ACS UDF F850LP image which was rebinned to the
same pixel scale. These form the NICMOS version 2.0 UDF images. The catalog
sources are chosen with a conservative detection limit to avoid the inclusion
of numerous spurious sources. The catalog contains 1293 objects in the 144 x
144 arc sececonds NICMOS subfield of the UDF. The 5 sigma signal to noise level
is an average 0.6 arc second diameter aperture AB magnitude of ~27.7 at 1.1 and
1.6 microns. The catalog sources, listed in order of right ascension, satisfy a
minimum signal to noise criterion of 1.4 sigma in at least 7 contiguous pixels
of the combined F110W and F160W imageComment: Accepted for publication in the Astronomical Journal. 33 Pages, 6
Figure
Anthropologists Respond to The Lancet EAT Commission
The Lancet Commissions are widely known as aspirational pieces, providing the mechanisms for consortia and networks of researchers to organize, collate, interrogate and publish around a range of subjects. Although the Commissions are predominantly led by biomedical scientists and cognate public health professionals, many address social science questions and involve social science expertise. Medical anthropologist David Napier was lead author of the Lancet Commission on Culture and Health (2014), for example, and all commissions on global health (https://www.thelancet.com/global-health/commissions) address questions of social structure, everyday life, the social determinants of health, and global inequalities.The Nutrire CoLab: Diana Burnett; Megan A. Carney; Lauren Carruth; Sarah Chard; Maggie Dickinson: Diana Burnett, Megan A. Carney, Lauren Carruth, Sarah Chard, Maggie Dickinson, Alyshia Gálvez, Hanna Garth, Jessica Hardin, Adele Hite, Heather Howard, Lenore Manderson, Emily Mendenhall, Abril Saldaña-Tejeda, Dana Simmons, Natali Valdez, Emily Vasquez, Megan Warin, Emily Yates-Doer
Rapid Evolution in the Most Luminous Galaxies During the First 900 Million Years
The first 900 million years (Myr) to redshift z~6 (the first seven per cent
of the age of the Universe) remains largely unexplored for the formation of
galaxies. Large samples of galaxies have been found at z~6, but detections at
earlier times are uncertain and unreliable. It is not at all clear how galaxies
built up from the first stars when the Universe was ~300 Myr old (z~12-15) to
z~6, just 600 Myr later. Here we report the results of a search for galaxies at
z~7-8, about 700 Myr after the Big Bang, using the deepest near-infrared and
optical images ever taken. Under conservative selection criteria we find only
one candidate galaxy at z~7-8, where ten would be expected if there were no
evolution in the galaxy population between z~7-8 and z~6. Using less
conservative criteria, there are four candidates, where 17 would be expected
with no evolution. This demonstrates that very luminous galaxies are quite rare
700 Myr after the Big Bang. The simplest explanation is that the Universe is
just too young to have built up many luminous galaxies at z~7-8 by the
hierarchical merging of small galaxies.Comment: Accepted for publication in Nature, 20 pages, 5 figures, 2 tables
(includes Supplementary Information), replaced to match version in pres
The Growth of Massive Galaxies Since z=2
We study the growth of massive galaxies from z=2 to the present using data
from the NEWFIRM Medium Band Survey. The sample is selected at a constant
number density of n=2x10^-4 Mpc^-3, so that galaxies at different epochs can be
compared in a meaningful way. We show that the stellar mass of galaxies at this
number density has increased by a factor of ~2 since z=2, following the
relation log(M)=11.45-0.15z. In order to determine at what physical radii this
mass growth occurred we construct very deep stacked rest-frame R-band images at
redshifts z=0.6, 1.1, 1.6, and 2.0. These image stacks of typically 70-80
galaxies enable us to characterize the stellar distribution to surface
brightness limits of ~28.5 mag/arcsec^2. We find that massive galaxies
gradually built up their outer regions over the past 10 Gyr. The mass within a
radius of r=5 kpc is nearly constant with redshift whereas the mass at 5-75 kpc
has increased by a factor of ~4 since z=2. Parameterizing the surface
brightness profiles we find that the effective radius and Sersic n parameter
evolve as r_e~(1+z)^-1.3 and n~(1+z)^-1.0 respectively. The data demonstrate
that massive galaxies have grown mostly inside-out, assembling their extended
stellar halos around compact, dense cores with possibly exponential radial
density distributions. Comparing the observed mass evolution to the average
star formation rates of the galaxies we find that the growth is likely
dominated by mergers, as in-situ star formation can only account for ~20% of
the mass build-up from z=2 to z=0. The main uncertainties in this study are
possible redshift-dependent systematic errors in the total stellar masses and
the conversion from light-weighted to mass-weighted radial profiles.Comment: Accepted for publication in the Astrophysical Journal. 26 pages, 13
figures in main tex
Massive Optically Dark Galaxies Unveiled by JWST Challenge Galaxy Formation Models
Over the past decade, the existence of a substantial population of optically
invisible, massive galaxies at has been implied from mid-infrared
to millimeter observations. With the unprecedented sensitivity of the JWST,
such extremely massive galaxy candidates have immediately been identified even
at , in much larger numbers than expected. These discoveries raised a hot
debate. If confirmed, early, high-mass galaxies challenge the current models of
galaxy formation. However, the lack of spectroscopic confirmations leads to
uncertain stellar mass () estimates, and the possible presence of
active galactic nuclei (AGN) adds further uncertainty. Here, we present the
first sample of 36 dust-obscured galaxies with robust spectroscopic redshifts
at from the JWST FRESCO survey. The three most extreme
sources at (1 billion years after the Big Bang) are so massive
(log ) that they would require, on average,
about 50% of the baryons in their halos to be converted into stars -- two to
three times higher than even the most efficient galaxies at later times. The
extended emission of these galaxies suggests limited contribution by AGN. This
population of ultra-massive galaxies accounts for 20% of the total cosmic star
formation rate density at , suggesting a substantial proportion of
extremely efficient star formation in the early Universe.Comment: Submitted to Nature. 22 pages, 4 main figures, 7 supplementary
figures, 3 supplementary tables. Comments are welcom
Somatic Variants in SVIL in Cerebral Aneurysms
Publisher Copyright: © American Academy of Neurology.Background and ObjectivesWhile somatic mutations have been well-studied in cancer, their roles in other complex traits are much less understood. Our goal is to identify somatic variants that may contribute to the formation of saccular cerebral aneurysms.MethodsWe performed whole-exome sequencing on aneurysm tissues and paired peripheral blood. RNA sequencing and the CRISPR/Cas9 system were then used to perform functional validation of our results.ResultsSomatic variants involved in supervillin (SVIL) or its regulation were found in 17% of aneurysm tissues. In the presence of a mutation in the SVIL gene, the expression level of SVIL was downregulated in the aneurysm tissue compared with normal control vessels. Downstream signaling pathways that were induced by knockdown of SVIL via the CRISPR/Cas9 system in vascular smooth muscle cells (vSMCs) were determined by evaluating changes in gene expression and protein kinase phosphorylation. We found that SVIL regulated the phenotypic modulation of vSMCs to the synthetic phenotype via Krüppel-like factor 4 and platelet-derived growth factor and affected cell migration of vSMCs via the RhoA/ROCK pathway.DiscussionWe propose that somatic variants form a novel mechanism for the development of cerebral aneurysms. Specifically, somatic variants in SVIL result in the phenotypic modulation of vSMCs, which increases the susceptibility to aneurysm formation. This finding suggests a new avenue for the therapeutic intervention and prevention of cerebral aneurysms.Peer reviewe
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