226 research outputs found
Comment 1, [in:] Extending the lighting design objectives procedure for holistic lighting solutions
Ariel - Volume 11 Number 3
Executive Editors
Ellen Feldman
Leonardo S. Nasca, Jr.
Business Managers
Barbara L. Davies
Martin B. Getzow
News Editor
Hugh A. Gelabert
Features Editor
Aaron D. Bleznak
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Joan M. Greco
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Samuel Markind
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Todd Demmy
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Paul F. Mansfiel
Detection of Helium in the Atmosphere of the Exo-Neptune HAT-P-11b
The helium absorption triplet at a wavelength of 10,833 \AA\ has been
proposed as a way to probe the escaping atmospheres of exoplanets. Recently
this feature was detected for the first time using Hubble Space Telescope (HST)
WFC3 observations of the hot Jupiter WASP-107b. We use similar HST/WFC3
observations to detect helium in the atmosphere of the hot Neptune HAT-P-11b at
the confidence level. We compare our observations to a grid of 1D
models of hydrodynamic escape to constrain the thermospheric temperatures and
mass loss rate. We find that our data are best fit by models with high mass
loss rates of - g s. Although we do
not detect the planetary wind directly, our data are consistent with the
prediction that HAT-P-11b is experiencing hydrodynamic atmospheric escape.
Nevertheless, the mass loss rate is low enough that the planet has only lost up
to a few percent of its mass over its history, leaving its bulk composition
largely unaffected. This matches the expectation from population statistics,
which indicate that close-in planets with radii greater than 2 R
form and retain H/He-dominated atmospheres. We also confirm the independent
detection of helium in HAT-P-11b obtained with the CARMENES instrument, making
this the first exoplanet with the detection of the same signature of
photoevaporation from both ground- and space-based facilities.Comment: 12 pages, 9 figures, accepted for publication in ApJ
Metrology of silicon photovoltaic cells using coherence correlation interferometry
Surface metrology plays an important role in the
development and manufacture of photovoltaic cells and
modules. Coherence Correlation Interferometry (CCI) is a
non-contacting surface metrology tool with potentially
important applications in the characterization of
photovoltaic devices. Its major advantages are that it is
fast, non-destructive and it takes its data from a relatively
large and hence representative area. A special mode,
called “stitching x-y” can be used to provide information on
a wider area, combining measurements taken in different
zones of the sample. The technique is capable of
providing surface roughness and step height
measurements with sub-nanometre precision. It is also
capable of measuring quantitatively surface texture and
surface form in three dimensions and it now has a new
capability to measure thin film and thick film thickness.
CCI measurements are presented on a range of features
on silicon photovoltaic cells including surface roughness,
surface texture, the profile of laser grooves for buried
contacts as well as the roughness and thickness of silicon
nitride thin films. Complementary analysis using
spectroscopic ellipsometry is also presented for
verification. CCI is a sensitive, non-destructive metrology
technique with potential use as an in-line quality
assurance tool in the large scale production of
photovoltaic modules
Sonic hedgehog expressing and responding cells generate neuronal diversity in the medial amygdala
<p>Abstract</p> <p>Background</p> <p>The mammalian amygdala is composed of two primary functional subdivisions, classified according to whether the major output projection of each nucleus is excitatory or inhibitory. The posterior dorsal and ventral subdivisions of the medial amygdala, which primarily contain inhibitory output neurons, modulate specific aspects of innate socio-sexual and aggressive behaviors. However, the development of the neuronal diversity of this complex and important structure remains to be fully elucidated.</p> <p>Results</p> <p>Using a combination of genetic fate-mapping and loss-of-function analyses, we examined the contribution and function of <it>Sonic hedgehog </it>(<it>Shh</it>)-expressing and <it>Shh</it>-responsive (<it>Nkx2-1</it><sup>+ </sup>and <it>Gli1</it><sup>+</sup>) neurons in the medial amygdala. Specifically, we found that <it>Shh- </it>and <it>Nkx2-1-</it>lineage cells contribute differentially to the dorsal and ventral subdivisions of the postnatal medial amygdala. These <it>Shh</it>- and <it>Nkx2-1</it>-lineage neurons express overlapping and non-overlapping inhibitory neuronal markers, such as Calbindin, FoxP2, nNOS and Somatostatin, revealing diverse fate contributions in discrete medial amygdala nuclear subdivisions. Electrophysiological analysis of the <it>Shh</it>-derived neurons additionally reveals an important functional diversity within this lineage in the medial amygdala. Moreover, inducible <it>Gli1<sup>CreER(T2) </sup></it>temporal fate mapping shows that early-generated progenitors that respond to <it>Shh </it>signaling also contribute to medial amygdala neuronal diversity. Lastly, analysis of <it>Nkx2-1 </it>mutant mice demonstrates a genetic requirement for <it>Nkx2-1 </it>in inhibitory neuronal specification in the medial amygdala distinct from the requirement for <it>Nkx2-1 </it>in cerebral cortical development.</p> <p>Conclusions</p> <p>Taken together, these data reveal a differential contribution of <it>Shh-</it>expressing and <it>Shh</it>-responding cells to medial amygdala neuronal diversity as well as the function of <it>Nkx2-1 </it>in the development of this important limbic system structure.</p
A HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b
Secondary eclipse observations of several of the hottest hot Jupiters show
featureless, blackbody-like spectra or molecular emission features, which are
consistent with thermal inversions being present in those atmospheres. Theory
predicts a transition between warmer atmospheres with thermal inversions and
cooler atmospheres without inversions, but the exact transition point is
unknown. In order to further investigate this issue, we observed two secondary
eclipses of the hot Jupiter HAT-P-7b with the Hubble Space Telescope (HST) WFC3
instrument and combined these data with previous Spitzer and Kepler secondary
eclipse observations. The HST and Spitzer data can be well fit by a blackbody
with K, and the Kepler data point constrains the geometric
albedo to . We modeled these data with a 3D GCM and 1D
self-consistent forward models. The 1D models indicate that the atmosphere has
a thermal inversion, weak heat redistribution, and water dissociation that
limits the range of pressures probed. This result suggests that WFC3
observations of HAT-P-7b and possibly some other ultra-hot Jupiters appear
blackbody-like because they probe a region near the tropopause where the
atmospheric temperature changes slowly with pressure. Additionally, the 1D
models constrain the atmospheric metallicity
() and the carbon-to-oxygen ratio (C/O
at 99 % confidence). The solar composition 3D GCM matches the Spitzer data but
generally underpredicts the flux in the WFC3 bandpass and cannot reproduce its
featureless shape. This discrepancy could be explained by high atmospheric drag
or nightside clouds, and may be better understood through further observation
with the James Webb Space Telescope (JWST).Comment: 14 pages, 10 figures, submitted to AAS Journal
Eigenspectra: A Framework for Identifying Spectra from 3D Eclipse Mapping
Planetary atmospheres are inherently 3D objects that can have strong
gradients in latitude, longitude, and altitude. Secondary eclipse mapping is a
powerful way to map the 3D distribution of the atmosphere, but the data can
have large correlations and errors in the presence of photon and instrument
noise. We develop a technique to mitigate the large uncertainties of eclipse
maps by identifying a small number of dominant spectra to make them more
tractable for individual analysis via atmospheric retrieval. We use the
eigencurves method to infer a multi-wavelength map of a planet from
spectroscopic secondary eclipse light curves. We then apply a clustering
algorithm to the planet map to identify several regions with similar emergent
spectra. We combine the similar spectra together to construct an
"eigenspectrum" for each distinct region on the planetary map. We demonstrate
how this approach could be used to isolate hot from cold regions and/or regions
with different chemical compositions in observations of hot Jupiters with the
James Webb Space Telescope (JWST). We find that our method struggles to
identify sharp edges in maps with sudden discontinuities, but generally can be
used as a first step before a more physically motivated modeling approach to
determine the primary features observed on the planet.Comment: 13 pages, 17 figures, accepted to MNRA
The Book of Mick: A Collaboration Chapter 17
Eighteen international ceramic authors were approached to be involved in this collaborative novel, exploring the history of wood firing in Australia, New Zealand, Japan and the United States. It was published as part of the proceedings of the Smoke on the Water 2017 Australian Woodfired Ceramics Conference, Cooroy, Queensland, Australia.
The Book of Mick utilises the creative medium of the novel to explore the unique experiences of Australian woodfired ceramics, along with the associated educational, cultural, governmental and personal experiences that have shaped the development of this art form over the last 50 years
StemBond hydrogels control the mechanical microenvironment for pluripotent stem cells.
Studies of mechanical signalling are typically performed by comparing cells cultured on soft and stiff hydrogel-based substrates. However, it is challenging to independently and robustly control both substrate stiffness and extracellular matrix tethering to substrates, making matrix tethering a potentially confounding variable in mechanical signalling investigations. Moreover, unstable matrix tethering can lead to poor cell attachment and weak engagement of cell adhesions. To address this, we developed StemBond hydrogels, a hydrogel in which matrix tethering is robust and can be varied independently of stiffness. We validate StemBond hydrogels by showing that they provide an optimal system for culturing mouse and human pluripotent stem cells. We further show how soft StemBond hydrogels modulate stem cell function, partly through stiffness-sensitive ERK signalling. Our findings underline how substrate mechanics impact mechanosensitive signalling pathways regulating self-renewal and differentiation, indicating that optimising the complete mechanical microenvironment will offer greater control over stem cell fate specification
A New Analysis of 8 Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b
With over 30 phase curves observed during the warm Spitzer mission, the
complete data set provides a wealth of information relating to trends and
three-dimensional properties of hot Jupiter atmospheres. In this work we
present a comparative study of seven new Spitzer phase curves for four planets
with equilibrium temperatures of T 1300K: Qatar-2b, WASP-52b,
WASP-34b, and WASP-140b, as well as the reanalysis of the 4.5 \micron
Qatar-1b phase curve due to the similar equilibrium temperature. In total, five
4.5 \micron phase curves and three 3.6 \micron phase curves are analyzed
here with a uniform approach. Using these new results, in combination with
literature values for the entire population of published Spitzer phase curves
of hot Jupiters, we present evidence for a linear trend of increasing hot spot
offset with increasing orbital period, as well as observational evidence for
two classes of planets in apparent redistribution vs. equilibrium temperature
parameter space, and tentative evidence for a dependence of hot spot offset on
planetary surface gravity in our 1300 K sample. We do not find trends in
apparent heat redistribution with orbital period or gravity. Non-uniformity in
literature Spitzer data analysis techniques precludes a definitive
determination of the sources or lack of trends.Comment: 22 pages, 13 figures, 6 tables. Accepted for publication in AAS
journal
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