372 research outputs found
Semaphorin 3A Contributes to Distal Pulmonary Epithelial Cell Differentiation and Lung Morphogenesis
altered distal lung structure.) littermate controls. mice that survived the immediate perinatal period. Furthermore, Sema3A deletion was linked with enhanced postnatal alveolar septal cell death.These data suggest that Sema3A modulates distal pulmonary epithelial cell development and alveolar septation. Defining how Sema3A influences structural plasticity of the developing lung is a critical first step for determining if this pathway can be exploited to develop innovative strategies for repair after acute or chronic lung injury
Probing Ganymede's atmosphere with HST Ly images in transit of Jupiter
We report results from far-ultraviolet observations by the Hubble Space
Telescope of Jupiter's largest moon Ganymede transiting across the planet's
dayside hemisphere. {Within} a targeted campaign on 9 September 2021 two
exposures were taken during one transit passage to probe for attenuation of
Jupiter's hydrogen Lyman- dayglow above the moon limb. The background
dayglow is slightly attenuated over an extended region around Ganymede, with
stronger attenuation in the second exposure when Ganymede was near the planet's
center. In the first exposure when the moon was closer to Jupiter's limb, the
effects from the Ganymede corona are hardly detectable, likely because the
Jovian Lyman- dayglow is spectrally broader and less intense at this
viewing geometry. The obtained vertical H column densities of around
~cm are consistent with previous results.
Constraining angular variability around Ganymede's disk, we derive an upper
limit on a local HO column density of ~cm, such
as could arise from outgassing plumes in regions near the observed moon limb
Constraints on Europa's water group torus from HST/COS observations
In-situ plasma measurements as well as remote mapping of energetic neutral
atoms around Jupiter provide indirect evidence that an enhancement of neutral
gas is present near the orbit of the moon Europa. Simulations suggest that such
a neutral gas torus can be sustained by escape from Europa's atmosphere and
consists primarily of molecular hydrogen, but the neutral gas torus has not yet
been measured directly through emissions or in-situ. Here we present
observations by the Cosmic Origins Spectrograph of the Hubble Space Telescope
(HST/COS) from 2020 and 2021, which scanned the equatorial plane between 8 and
10 planetary radii west of Jupiter. No neutral gas emissions are detected. We
derive upper limits on the emissions and compare these to modelled emissions
from electron impact and resonant scattering using a Europa torus Monte Carlo
model for the neutral gases. The comparison supports the previous findings that
the torus is dilute and primarily consists of molecular hydrogen. A detection
of sulfur ion emissions radially inward of the Europa orbit is consistent with
emissions from the extended Io torus and with sulfur ion fractional abundances
as previously detected
Non-perturbative effects and the refined topological string
The partition function of ABJM theory on the three-sphere has
non-perturbative corrections due to membrane instantons in the M-theory dual.
We show that the full series of membrane instanton corrections is completely
determined by the refined topological string on the Calabi-Yau manifold known
as local P1xP1, in the Nekrasov-Shatashvili limit. Our result can be
interpreted as a first-principles derivation of the full series of
non-perturbative effects for the closed topological string on this Calabi-Yau
background. Based on this, we make a proposal for the non-perturbative free
energy of topological strings on general, local Calabi-Yau manifolds.Comment: 38 pages, 5 figure
Final results from the Palo Verde Neutrino Oscillation Experiment
The analysis and results are presented from the complete data set recorded at
Palo Verde between September 1998 and July 2000. In the experiment, the
\nuebar interaction rate has been measured at a distance of 750 and 890 m
from the reactors of the Palo Verde Nuclear Generating Station for a total of
350 days, including 108 days with one of the three reactors off for refueling.
Backgrounds were determined by (a) the technique based on the difference
between signal and background under reversal of the positron and neutron parts
of the correlated event and (b) making use of the conventional reactor-on and
reactor-off cycles. There is no evidence for neutrino oscillation and the mode
\nuebar\to\bar\nu_x was excluded at 90% CL for \dm>1.1\times10^{-3} eV
at full mixing, and \sinq>0.17 at large \dm.Comment: 11 pages, 8 figure
Long-term safety, efficacy and inhibition of radiographic progression with abatacept treatment in patients with rheumatoid arthritis and an inadequate response to methotrexate: 3-year results from the AIM trial
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Mid-ultraviolet Hubble Observations of Europa and the Global Surface Distribution of SO<sub>2</sub>
We present spatially resolved reflectance spectra of Europa’s surface in the wavelength range of 210–315 nm obtained by the Hubble Space Telescope Imaging Spectrograph in 2018 and 2019. These data provide the first high-quality, near-global spectral observations of Europa from 210 to 240 nm. They show that the reflectance of Europa’s leading, trailing, anti-Jovian, and sub-Jovian hemispheres is ∼5% near 210 nm, with varying spectral slopes across the mid-UV. This low albedo, even on the more “pristine” leading hemisphere, indicates a lack of the signature far-UV spectral edge characteristic of water ice. We detected and mapped a strong absorption feature at 280 nm that is consistent with an S–O bond that has previously been attributed to SO2 on the surface, hypothesized to be formed through radiolytic processing of Iogenic sulfur ions that have been preferentially emplaced on Europa’s trailing hemisphere by Jupiter’s magnetic field. Our models show that small inclusions of SO2 (0.1%) within the water ice are sufficient to produce the 280 nm feature without producing a feature at 4.07 μm, which has not been observed in ground-based spectral observations of Europa. This data set is the first to produce a spatially resolved, near-global map of the assumed SO2 feature, which is primarily concentrated near the apex of the trailing hemisphere and correlated with large-scale darker regions in both the visible and the ultraviolet. This distribution is consistent with “cold” exogenic sulfur ion bombardment on Europa
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