405 research outputs found
Mastermind Acts Downstream of Notch to Specify Neuronal Cell Fates in theDrosophilaCentral Nervous System
AbstractIn theDrosophilacentral nervous system, cellular diversity is generated through the asymmetric partitioning of cell fate determinants at cell division. Neural precursors (or neuroblasts) divide in a stem cell lineage to generate a series of ganglion mother cells, each of which divides once to produce a pair of postmitotic neurons or glial cells. An exception to this rule is the MP2 neuroblast, which divides only once to generate two neurons. We screened for genes expressed in the MP2 neuroblast and its progeny as a means of identifying the factors that specify cell fate in the MP2 lineage. We identified a P-element insertion line that expresses the reporter gene, tau-ÎČ-galactosidase, in the MP2 precursor and its progeny, the vMP2 and dMP2 neurons. The transposon disrupts the neurogenic gene,mastermind,but does not lead to neural hyperplasia. However, the vMP2 neuron is transformed into its sibling cell, dMP2. By contrast, expression of a dominant activated form of the Notch receptor in the MP2 lineage transforms dMP2 to vMP2. Notch signalling requires Mastermind, suggesting that Mastermind acts downstream of Notch to determine the vMP2 cell fate. We show that Mastermind plays a similar role in the neurons derived from ganglion mother cells 1-1a and 4-2a, where it specifies the pCC and RP2sib fates, respectively. This suggests that Notch signalling through Mastermind plays a wider role in specifying neuronal identity in theDrosophilacentral nervous system
The inner dark matter distribution of the Cosmic Horseshoe (J1148+1930) with gravitational lensing and dynamics
We present a detailed analysis of the inner mass structure of the Cosmic
Horseshoe (J1148+1930) strong gravitational lens system observed with the
Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). In addition to the
spectacular Einstein ring, this systems shows a radial arc. We obtained the
redshift of the radial arc counter image from
Gemini observations. To disentangle the dark and luminous matter, we consider
three different profiles for the dark matter distribution: a power-law profile,
the NFW, and a generalized version of the NFW profile. For the luminous matter
distribution, we base it on the observed light distribution that is fitted with
three components: a point mass for the central light component resembling an
active galactic nucleus, and the remaining two extended light components scaled
by a constant M/L. To constrain the model further, we include published
velocity dispersion measurements of the lens galaxy and perform a
self-consistent lensing and axisymmetric Jeans dynamical modeling. Our model
fits well to the observations including the radial arc, independent of the dark
matter profile. Depending on the dark matter profile, we get a dark matter
fraction between 60 % and 70 %. With our composite mass model we find that the
radial arc helps to constrain the inner dark matter distribution of the Cosmic
Hoseshoe independently of the dark matter profile.Comment: 19 pages, 14 figures, 8 tables, submitted to A&
The Right Angle: Visual Portrayal of Products Affects Observersâ Impressions of Owners
Consumer products have long been known to influence observersâ impressions of product owners. The angle at which products are visually portrayed in advertisements, however, may be an overlooked factor in these effects. We hypothesize and find that portrayals of the same product from different viewpoints can prime different associations that color impressions of product and owner in parallel ways. In Study 1, automobiles were rated higher on statusâ and powerârelated traits (e.g., dominant , powerful ) when portrayed headâon versus in side profile, an effect found for sport utility vehicles (SUVs)âa category with a reputation for dominanceâbut not sedans. In Study 2, these portrayalâbased associations influenced the impressions formed about the product's owner: a target person was rated higher on statusâ and powerârelated traits when his SUV was portrayed headâon versus in side profile. These results suggest that the influence of visual portrayal extends beyond general evaluations of products to affect more specific impressions of products and owners alike, and highlight that primed traits are likely to influence impressions when compatible with other knowledge about the target.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93734/1/mar20557.pd
Sprays for Control of Sycamore Anthracnose
Sycamore anthracnose, Gnomonia veneta, (Sacc. & Speg.) Klebahn (4), prevalent in Iowa (1), belongs to a group of plant diseases with life cycle patterns which suggest the use of fungicidal sprays for their control. In early spring this disease appears as a blight on the young leaves soon after they emerge from the bud (Fig. 1). The blighted leaves become brown to black and frequently appear as if they had been injured by frost. Mature leaf infection characteristically produces elongate brown streaks along the midveins and laterals (Fig. 2), and many such infected leaves fall within two or three weeks. In addition to defoliation, sycamores undergo extensive twig blight. The death of terminal buds stimulates the development of numerous lateral branches which later may also be destroyed. This results in dead clusters of branches, witches\u27 broom , around a swollen terminal area (Fig. 3)
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Time-to-explosion thermal initiation test for explosives
A controlled series of experiments have been performed in an attempt to evaluate the Henkin time-to-explosion test as a reactivity test and a quality assurance tool. This was done by comparing the Henkin results with those obtained with the presently used gas chromatograph chemical reactivity test, Two explosives, PBX 9404 and LX-04-1, were tested with four ``inerts``: sodium chloride, lead powder, Silastic Q-300030 and epoxy 633111. The experimental data from the two tests are given; a method for mathematically reducing the Henkin data is considered. The data from the two tests are not in complete agreement. Both predict that the epoxy is reactive with and that NaCl is unreactive with both explosives. However, the Henkin data indicated reactivity of lead powder and Silastic with LX-04-1; the gas chromatograph did not. For PBX 9404, the Henkin test indicated that the lead was borderline reactive and the Silastic unreactive, while the gas chromatograph predicted the opposite. DTA thermograms are included to help interpret the comparison test results. A section in the appendix is devoted to the experimental problems encountered in getting the Henkin test operational. All raw data generated during that time are included in the appendix. In addition, data obtained subsequently with a fairly wide variety of explosives (and propellants) are given; these indicate the present quality of data
HOLISMOKES -- X. Comparison between neural network and semi-automated traditional modeling of strong lenses
Modeling of strongly gravitationally lensed galaxies is often required in
order to use them as astrophysical or cosmological probes. With current and
upcoming wide-field imaging surveys, the number of detected lenses is
increasing significantly such that automated and fast modeling procedures for
ground-based data are urgently needed. This is especially pertinent to
short-lived lensed transients in order to plan follow-up observations.
Therefore, we present in a companion paper (submitted) a neural network
predicting the parameter values with corresponding uncertainties of a Singular
Isothermal Ellipsoid (SIE) mass profile with external shear. In this work, we
present a newly-developed pipeline glee_auto.py to model consistently any
galaxy-scale lensing system. In contrast to previous automated modeling
pipelines that require high-resolution images, glee_auto.py is optimized for
ground-based images such as those from the Hyper-Suprime-Cam (HSC) or the
upcoming Rubin Observatory Legacy Survey of Space and Time. We further present
glee_tools.py, a flexible automation code for individual modeling that has no
direct decisions and assumptions implemented. Both pipelines, in addition to
our modeling network, minimize the user input time drastically and thus are
important for future modeling efforts. We apply the network to 31 real
galaxy-scale lenses of HSC and compare the results to the traditional models.
In the direct comparison, we find a very good match for the Einstein radius
especially for systems with ". The lens mass center and
ellipticity show reasonable agreement. The main discrepancies are on the
external shear as expected from our tests on mock systems. In general, our
study demonstrates that neural networks are a viable and ultra fast approach
for measuring the lens-galaxy masses from ground-based data in the upcoming era
with lenses expected.Comment: 17+28 pages, 7+31 figures, 2+5 tables, submitted to A&
HOLISMOKES -- IV. Efficient mass modeling of strong lenses through deep learning
Modelling the mass distributions of strong gravitational lenses is often
necessary to use them as astrophysical and cosmological probes. With the high
number of lens systems () expected from upcoming surveys, it is timely
to explore efficient modeling approaches beyond traditional MCMC techniques
that are time consuming. We train a CNN on images of galaxy-scale lenses to
predict the parameters of the SIE mass model (, and ).
To train the network, we simulate images based on real observations from the
HSC Survey for the lens galaxies and from the HUDF as lensed galaxies. We
tested different network architectures, the effect of different data sets, and
using different input distributions of . We find that the CNN
performs well and obtain with the network trained with a uniform distribution
of the following median values with scatter:
, ,
,
and . The bias in is driven by
systems with small . Therefore, when we further predict the multiple
lensed image positions and time delays based on the network output, we apply
the network to the sample limited to . In this case, the offset
between the predicted and input lensed image positions is
and for and ,
respectively. For the fractional difference between the predicted and true time
delay, we obtain . Our CNN is able to predict the SIE
parameters in fractions of a second on a single CPU and with the output we can
predict the image positions and time delays in an automated way, such that we
are able to process efficiently the huge amount of expected lens detections in
the near future.Comment: 17 pages, 14 Figure
HOLISMOKES -- IX. Neural network inference of strong-lens parameters and uncertainties from ground-based images
Modeling of strong gravitational lenses is a necessity for further
applications in astrophysics and cosmology. Especially with the large number of
detections in current and upcoming surveys such as the Rubin Legacy Survey of
Space and Time (LSST), it is timely to investigate in automated and fast
analysis techniques beyond the traditional and time consuming Markov chain
Monte Carlo sampling methods. Building upon our convolutional neural network
(CNN) presented in Schuldt et al. (2021b), we present here another CNN,
specifically a residual neural network (ResNet), that predicts the five mass
parameters of a Singular Isothermal Ellipsoid (SIE) profile (lens center
and , ellipticity and , Einstein radius ) and the
external shear (, ) from ground-based imaging
data. In contrast to our CNN, this ResNet further predicts a 1
uncertainty for each parameter. To train our network, we use our improved
pipeline from Schuldt et al. (2021b) to simulate lens images using real images
of galaxies from the Hyper Suprime-Cam Survey (HSC) and from the Hubble Ultra
Deep Field as lens galaxies and background sources, respectively. We find
overall very good recoveries for the SIE parameters, while differences remain
in predicting the external shear. From our tests, most likely the low image
resolution is the limiting factor for predicting the external shear. Given the
run time of milli-seconds per system, our network is perfectly suited to
predict the next appearing image and time delays of lensed transients in time.
Therefore, we also present the performance of the network on these quantities
in comparison to our simulations. Our ResNet is able to predict the SIE and
shear parameter values in fractions of a second on a single CPU such that we
are able to process efficiently the huge amount of expected galaxy-scale lenses
in the near future.Comment: 16 pages, including 11 figures, accepted for publication by A&
Constraining the multi-scale dark-matter distribution in CASSOWARY 31 with strong gravitational lensing and stellar dynamics
We study the inner structure of the group-scale lens CASSOWARY 31 (CSWA 31)
by adopting both strong lensing and dynamical modeling. CSWA 31 is a peculiar
lens system. The brightest group galaxy (BGG) is an ultra-massive elliptical
galaxy at z = 0.683 with a weighted mean velocity dispersion of km s. It is surrounded by group members and several lensed arcs
probing up to ~150 kpc in projection. Our results significantly improve
previous analyses of CSWA 31 thanks to the new HST imaging and MUSE
integral-field spectroscopy. From the secure identification of five sets of
multiple images and measurements of the spatially-resolved stellar kinematics
of the BGG, we conduct a detailed analysis of the multi-scale mass distribution
using various modeling approaches, both in the single and multiple lens-plane
scenarios. Our best-fit mass models reproduce the positions of multiple images
and provide robust reconstructions for two background galaxies at z = 1.4869
and z = 2.763. The relative contributions from the BGG and group-scale halo are
remarkably consistent in our three reference models, demonstrating the
self-consistency between strong lensing analyses based on image position and
extended image modeling. We find that the ultra-massive BGG dominates the
projected total mass profiles within 20 kpc, while the group-scale halo
dominates at larger radii. The total projected mass enclosed within =
27.2 kpc is M. We find that CSWA
31 is a peculiar fossil group, strongly dark-matter dominated towards the
central region, and with a projected total mass profile similar to higher-mass
cluster-scale halos. The total mass-density slope within the effective radius
is shallower than isothermal, consistent with previous analyses of early-type
galaxies in overdense environments.Comment: 22 pages, 12 figures, 5 tables, submitted to Astronomy &
Astrophysics. We welcome the comments from reader
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