182 research outputs found
Strategy for Dynamic Wisp Removal in James Webb Space Telescope NIRCam Images
The James Webb Space Telescope (JWST) near-infrared camera (NIRCam) has been
found to exhibit serious wisp-like structures in four of its eight
short-wavelength detectors. The exact structure and strength of these wisps is
highly variable with the position and orientation of JWST, so the use of static
templates is non-optimal. Here we investigate a dynamic strategy to mitigate
these wisps using long-wavelength reference images. Based on a suite of
experiments where we embed a worst-case scenario median-stacked wisp into
wisp-free images, we define suitable parameters for our wisp removal strategy.
Using this setup we re-process wisp-affected public Prime Extragalactic Areas
for Reionization and Lensing Science (PEARLS) data in the North Ecliptic Pole
Time Domain Field (NEP-TDF) field, resulting in significant visual improvement
in our detector frames and reduced noise in the final stacked images.Comment: 16 pages, 10 figures, submitted to PASP, comments welcom
Bisphosphonates Inhibit Expression of p63 by Oral Keratinocytes
Osteonecrosis of the jaw (ONJ), a side-effect of bisphosphonate therapy, is characterized by exposed bone that fails to heal within eight weeks. Healing time of oral epithelial wounds is decreased in the presence of amino-bisphosphonates; however, the mechanism remains unknown. We examined human tissue from individuals with ONJ and non-bisphosphonate-treated controlindividuals to identify changes in oral epithelium and connective tissue. Oral and intravenous bisphosphonate-treated ONJ sites had reduced numbers of basal epithelial progenitor cells, as demonstrated by a 13.8 ± 1.1% and 31.9 ± 5.8% reduction of p63 expression, respectively. No significant differences in proliferation rates, vessel density, or macrophage number were noted. In vitro treatment of clonal and primary oral keratinocytes with zoledronic acid (ZA) inhibited p63, and expression was rescued by the addition of mevalonate pathway intermediates. In addition, both ZA treatment and p63 shRNA knock-down impaired formation of 3D Ex Vivo Produced Oral Mucosa Equivalents (EVPOME) and closure of an in vitro scratch assay. Analysis of our data suggests that bisphosphonate treatment may delay oral epithelial healing by interfering with p63-positive progenitor cells in the basal layer of the oral epithelium in a mevalonate-pathway-dependent manner. This delay in healing may increase the likelihood of osteonecrosis developing in already-compromised bone
Training for a First-Time Marathon Reverses Age-Related Aortic Stiffening.
BACKGROUND: Aging increases aortic stiffness, contributing to cardiovascular risk even in healthy individuals. Aortic stiffness is reduced through supervised training programs, but these are not easily generalizable. OBJECTIVES: The purpose of this study was to determine whether real-world exercise training for a first-time marathon can reverse age-related aortic stiffening. METHODS: Untrained healthy individuals underwent 6 months of training for the London Marathon. Assessment pre-training and 2 weeks post-marathon included central (aortic) blood pressure and aortic stiffness using cardiovascular magnetic resonance distensibility. Biological "aortic age" was calculated from the baseline chronological age-stiffness relationship. Change in stiffness was assessed at the ascending (Ao-A) and descending aorta at the pulmonary artery bifurcation (Ao-P) and diaphragm (Ao-D). Data are mean changes (95% confidence intervals [CIs]). RESULTS: A total of 138 first-time marathon completers (age 21 to 69 years, 49% male) were assessed, with an estimated training schedule of 6 to 13 miles/week. At baseline, a decade of chronological aging correlated with a decrease in Ao-A, Ao-P, and Ao-D distensibility by 2.3, 1.9, and 3.1 à 10-3 mm Hg-1, respectively (p < 0.05 for all). Training decreased systolic and diastolic central (aortic) blood pressure by 4 mm Hg (95% CI: 2.8 to 5.5 mm Hg) and 3 mm Hg (95% CI: 1.6 to 3.5 mm Hg). Descending aortic distensibility increased (Ao-P: 9%; p = 0.009; Ao-D: 16%; p = 0.002), while remaining unchanged in the Ao-A. These translated to a reduction in "aortic age" by 3.9 years (95% CI: 1.1 to 7.6 years) and 4.0 years (95% CI: 1.7 to 8.0 years) (Ao-P and Ao-D, respectively). Benefit was greater in older, male participants with slower running times (p < 0.05 for all). CONCLUSIONS: Training for and completing a marathon even at relatively low exercise intensity reduces central blood pressure and aortic stiffness-equivalent to a âŒ4-year reduction in vascular age. Greater rejuvenation was observed in older, slower individuals
On the tidal interaction of a solar-type star with an orbiting companion: Excitation of g mode oscillation and orbital evolution
We calculate the dynamical tides raised on a non-rotating solar-type star by
a close stellar or planetary companion. Dissipation arising from a turbulent
viscosity operating in the convection zone and radiative damping in the
radiative core are considered. We compute the torque exerted on the star by a
companion in circular orbit, and determine the potentially observable magnitude
of the tidally induced velocity at the stellar photosphere. These calculations
are compared with the results obtained by assuming that a very small frequency
limit can be taken in order to calculate the tidal response (equilibrium tide).
For a standard solar model, the latter is found to give a relatively poor
approximation at the periods of interest of several days, even when the system
is far from resonance with a normal mode. It is shown that although the
companion may go through a succession of resonances as it spirals in under the
action of the tides, for a fixed spectrum of normal modes its migration is
controlled essentially by the non-resonant interaction. We find that the
turbulent viscosity that is required to provide the observed circularization
rates of main sequence solar-type binaries is about fifty times larger than
that simply estimated from mixing length theory for non-rotating stars. We
discuss the means by which this enhanced viscosity might be realized. These
calculations are applied to 51 Pegasi. We show that the perturbed velocity
induced by the tides at the stellar surface is too small to be observed.Comment: 36 pages including 6 PostScript figures, LaTex -- To be published in
ApJ -- Also available at http://www.ucolick.org/~ct/home.htm
Spectroscopy of the Supernova H0pe Host Galaxy at Redshift 1.78
Supernova (SN) H0pe was discovered as a new transient in James Webb Space
Telescope (JWST) NIRCam images of the galaxy cluster PLCK G165.7+67.0 taken as
part of the "Prime Extragalactic Areas for Reionization and Lensing Science"
(PEARLS) JWST GTO program (# 1176) on 2023 March 30 (AstroNote 2023-96; Frye et
al. 2023). The transient is a compact source associated with a background
galaxy that is stretched and triply-imaged by the cluster's strong
gravitational lensing. This paper reports spectra in the 950-1370 nm observer
frame of two of the galaxy's images obtained with Large Binocular Telescope
(LBT) Utility Camera in the Infrared (LUCI) in longslit mode two weeks after
the \JWST\ observations. The individual average spectra show the [OII] doublet
and the Balmer and 4000 Angstrom breaks at redshift z=1.783+/-0.002. The CIGALE
best-fit model of the spectral energy distribution indicates that SN H0pe's
host galaxy is massive (Mstar~6x10^10 Msun after correcting for a magnification
factor ~7) with a predominant intermediate age (~2 Gyr) stellar population,
moderate extinction, and a magnification-corrected star formation rate ~13
Msun/yr, consistent with being below the main sequence of star formation. These
properties suggest that H0pe might be a type Ia SN. Additional observations of
SN H0pe and its host recently carried out with JWST (JWST-DD-4446; PI: B. Frye)
will be able to both determine the SN classification and confirm its
association with the galaxy analyzed in this work.Comment: 6 pages, 4 figures, Letter accepted for publication in Astronomy &
Astrophysic
JWST's PEARLS: Improved Flux Calibration for NIRCam
The Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS),
a JWST GTO program, obtained a set of unique NIRCam observations that have
enabled us to significantly improve the default photometric calibration across
both NIRCam modules. The observations consisted of three epochs of 4-band
(F150W, F200W, F356W, and F444W) NIRCam imaging in the Spitzer IRAC Dark Field
(IDF). The three epochs were six months apart and spanned the full duration of
Cycle 1. As the IDF is in the JWST continuous viewing zone, we were able to
design the observations such that the two modules of NIRCam, modules A and B,
were flipped by 180 degrees and completely overlapped each other's footprints
in alternate epochs. We were therefore able to directly compare the photometry
of the same objects observed with different modules and detectors, and we found
significant photometric residuals up to ~ 0.05 mag in some detectors and
filters, for the default version of the calibration files that we used
(jwst_1039.pmap). Moreover, there are multiplicative gradients present in the
data obtained in the two long-wavelength bands. The problem is less severe in
the data reduced using the latest pmap (jwst_1130.pmap as of September 2023),
but it is still present, and is non-negligible. We provide a recipe to correct
for this systematic effect to bring the two modules onto a more consistent
calibration, to a photometric precision better than ~ 0.02 mag.Comment: 12 pages, 8 figures, 3 tables. Accepted to PAS
The case for a distributed solar dynamo shaped by near-surface shear
Arguments for and against the widely accepted picture of a solar dynamo being
seated in the tachocline are reviewed and alternative ideas concerning dynamos
operating in the bulk of the convection zone, or perhaps even in the
near-surface shear layer, are discussed. Based on the angular velocities of
magnetic tracers it is argued that the observations are compatible with a
distributed dynamo that may be strongly shaped by the near-surface shear layer.
Direct simulations of dynamo action in a slab with turbulence and shear are
presented to discuss filling factor and tilt angles of bipolar regions in such
a model.Comment: 10 pages, 6 figures, Astrophys. J. 625 (scheduled for the 1 June 2005
issue
PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a TRGB Distance of 31 Mpc
A wealth of observations have long suggested that the vast majority of
isolated classical dwarf galaxies (- M) are currently
star-forming. However, recent observations of the large abundance of
"Ultra-Diffuse Galaxies" beyond the reach of previous large spectroscopic
surveys suggest that our understanding of the dwarf galaxy population may be
incomplete. Here we report the serendipitous discovery of an isolated quiescent
dwarf galaxy in the nearby Universe, which was imaged as part of the PEARLS GTO
program. Remarkably, individual red-giant branch stars are visible in this
near-IR imaging, suggesting a distance of Mpc, and a wealth of archival
photometry point to an sSFR of yr. Spectra obtained
with the Lowell Discovery Telescope find a recessional velocity consistent with
the Hubble Flow and km/s separated from the nearest massive galaxy in
SDSS, suggesting that this galaxy was either quenched from internal mechanisms
or had a very high-velocity interaction with a nearby massive galaxy in the
past. This analysis highlights the possibility that many nearby quiescent dwarf
galaxies are waiting to be discovered and that JWST has the potential to
identify them.Comment: Submitted to ApJ Letters. Comments welcome
Magellanic System Stars Identified in the SMACS J0723.3-7327 JWST ERO Images
We identify 68 distant stars in JWST/NIRCam ERO images of the field of galaxy
cluster SMACS J0723.3-7327 (SMACS 0723). Given the relatively small
() angular separation between SMACS 0723 and the Large
Magellanic Cloud, it is likely that these stars are associated with the LMC
outskirts or Leading Arm. This is further bolstered by a spectral energy
distribution analysis, which suggests an excess of stars at a physical distance
of kpc, consistent with being associated with or located behind the
Magellanic system. In particular, we find that the overall surface density of
stars brighter than 27.0 mag in the field of SMACS 0723 is 2.3 times that
of stars in a blank field with similar galactic latitude (the North Ecliptic
Pole Time Domain Field), and that the density of stars in the SMACS 0723 field
with SED-derived distances consistent with the Magellanic system is 7.3
times larger than that of the blank field. The candidate stars at these
distances are consistent with a stellar population at the same distance modulus
with [Fe/H] and an age of Gyr. On the assumption that all
of the 68 stars are associated with the LMC, then the stellar density of the
LMC at the location of the SMACS 0723 field is stars kpc,
which helps trace the density of stars in the LMC outskirts.Comment: Submitted to ApJ, comments welcom
What should be done with antisocial personality disorder in the new edition of the diagnostic and statistical manual of mental disorders (DSM-V)?
Antisocial personality disorder, psychopathy, dissocial personality disorder and sociopathy are constructs that have generally been used to predict recidivism and dangerousness, alongside being used to exclude patients from treatment services. However, 'antisocial personality disorder' has recently begun to emerge as a treatment diagnosis, a development reflected within cognitive behaviour therapy and mentalisation-based psychotherapy. Many of the behaviour characteristics of antisocial personality disorder are, at the same time, being targeted by interventions at criminal justice settings. A significantly higher proportion of published articles focusing on antisocial personality concern treatment when compared to articles on psychopathy. Currently, the proposal for antisocial personality disorder for the Diagnostic and Statistical Manual of Mental Disorders, fifth edition, suggests a major change in the criteria for this disorder. While the present definition focuses mainly on observable behaviours, the proposed revision stresses interpersonal and emotional aspects of the disorder drawing on the concept of psychopathy. The present commentary suggests that developments leading to improvement in the diagnosis of this type of disorder should, rather than focusing exclusively on elements such as dangerousness and risk assessment, point us to ways in which patients can be treated for their problems
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