444 research outputs found
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses X. Modeling based on high-precision astrometry of a sample of 25 lensed quasars: consequences for ellipticity, shear, and astrometric anomalies
(abridged) Gravitationally lensed quasars can be used as powerful
cosmological and astrophysical probes. We can (i) infer the Hubble constant
based on the time-delay technique, (ii) unveil substructures along the l.o.s.
toward distant galaxies, and (iii) compare the shape and the slope of baryons
and dark matter distributions in galaxies. To reach these goals, we need
high-accuracy astrometry and morphology measurements of the lens. In this work,
we first present new astrometry for 11 lenses with measured time delays. Using
MCS deconvolution on NIC2 HST images, we reached an astrometric accuracy of
about 1-2.5 mas and an accurate shape measurement of the lens galaxy. Second,
we combined these measurements with those of 14 other systems to present new
mass models of these lenses. This led to the following results: 1) In 4
double-image quasars, we show that the influence of the lens environment on the
time delay can easily be quantified and modeled, hence putting these lenses
with high priority for time-delay determination. 2) For quadruple-image
quasars, the difficulty often encountered in reproducing the image positions to
milli-arcsec accuracy (astrometric anomaly) is overcome by explicitly including
the nearest visible galaxy in the model. However, one anomalous system
(J1131-1231) does not show any luminous perturber in its vicinity, and three
others (WFI2026-4536, WFI2033-4723, and B2045+265) have problematic modeling.
These 4 systems are the best candidates for a pertubation by a dark matter
substructure. 3) We find a significant correlation between the PA of the light
and of the mass distributions in lensing galaxies. In contrast with other
studies, we find that the ellipticity of the light and of the mass also
correlate well, suggesting that the overall spatial distribution of matter is
not very different from the baryon distribution in the inner \sim 5 kpc of
lensing galaxies.Comment: Accepted for publication in Astronomy and Astrophysics abridged
abstrac
TRAPPIST: a robotic telescope dedicated to the study of planetary systems
We present here a new robotic telescope called TRAPPIST (TRAnsiting Planets
and PlanetesImals Small Telescope). Equipped with a high-quality CCD camera
mounted on a 0.6 meter light weight optical tube, TRAPPIST has been installed
in April 2010 at the ESO La Silla Observatory (Chile), and is now beginning its
scientific program. The science goal of TRAPPIST is the study of planetary
systems through two approaches: the detection and study of exoplanets, and the
study of comets. We describe here the objectives of the project, the hardware,
and we present some of the first results obtained during the commissioning
phase.Comment: To appear in Detection and Dynamics of Transiting Exoplanets,
Proceedings of Haute Provence Observatory Colloquium (23-27 August 2010),
eds. F. Bouchy, R.F. Diaz & C.Moutou, Platypus press 201
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses IX. Time delays, lens dynamics and baryonic fraction in HE 0435-1223
We present accurate time delays for the quadruply imaged quasar HE 0435-1223.
The delays were measured from 575 independent photometric points obtained in
the R-band between January 2004 and March 2010. With seven years of data, we
clearly show that quasar image A is affected by strong microlensing variations
and that the time delays are best expressed relative to quasar image B. We
measured Delta_t(BC) = 7.8+/-0.8 days, Delta_t(BD) = -6.5+/-0.7 days and
Delta_t_CD = -14.3+/-0.8 days. We spacially deconvolved HST NICMOS2 F160W
images to derive accurate astrometry of the quasar images and to infer the
light profile of the lensing galaxy. We combined these images with a stellar
population fitting of a deep VLT spectrum of the lensing galaxy to estimate the
baryonic fraction, , in the Einstein radius. We measured f_b =
0.65+0.13-0.10 if the lensing galaxy has a Salpeter IMF and f_b =
0.45+0.04-0.07 if it has a Kroupa IMF. The spectrum also allowed us to estimate
the velocity dispersion of the lensing galaxy, sigma_ap = 222+/-34 km/s. We
used f_b and sigma_ap to constrain an analytical model of the lensing galaxy
composed of an Hernquist plus generalized NFW profile. We solve the Jeans
equations numerically for the model and explored the parameter space under the
additional requirement that the model must predict the correct astrometry for
the quasar images. Given the current error bars on f_b and sigma_ap, we did not
constrain H0 yet with high accuracy, i.e., we found a broad range of models
with chi^2 < 1. However, narrowing this range is possible, provided a better
velocity dispersion measurement becomes available. In addition, increasing the
depth of the current HST imaging data of HE 0435-1223 will allow us to combine
our constraints with lens reconstruction techniques that make use of the full
Einstein ring that is visible in this object.Comment: 12 pages, 10 figures, final version accepted for publication by A&
A Generative Deep Learning Approach to Stochastic Downscaling of Precipitation Forecasts
Despite continuous improvements, precipitation forecasts are still not as
accurate and reliable as those of other meteorological variables. A major
contributing factor to this is that several key processes affecting
precipitation distribution and intensity occur below the resolved scale of
global weather models. Generative adversarial networks (GANs) have been
demonstrated by the computer vision community to be successful at
super-resolution problems, i.e., learning to add fine-scale structure to coarse
images. Leinonen et al. (2020) previously applied a GAN to produce ensembles of
reconstructed high-resolution atmospheric fields, given coarsened input data.
In this paper, we demonstrate this approach can be extended to the more
challenging problem of increasing the accuracy and resolution of comparatively
low-resolution input from a weather forecasting model, using high-resolution
radar measurements as a "ground truth". The neural network must learn to add
resolution and structure whilst accounting for non-negligible forecast error.
We show that GANs and VAE-GANs can match the statistical properties of
state-of-the-art pointwise post-processing methods whilst creating
high-resolution, spatially coherent precipitation maps. Our model compares
favourably to the best existing downscaling methods in both pixel-wise and
pooled CRPS scores, power spectrum information and rank histograms (used to
assess calibration). We test our models and show that they perform in a range
of scenarios, including heavy rainfall.Comment: Submitted to JAMES 4/4/2
NOD/SCID-GAMMA Mice Are an Ideal Strain to Assess the Efficacy of Therapeutic Agents Used in the Treatment of Myeloma Bone Disease
Animal models of multiple myeloma vary in terms of consistency of onset, degree of tumour burden and degree of myeloma bone disease. Here we describe five pre-clinical models of myeloma in NOD/SCID-GAMMA mice to specifically study the effects of therapeutic agents on myeloma bone disease. Groups of 7–8 week old female irradiated NOD/SCID-GAMMA mice were injected intravenously via the tail vein with either 1x106 JJN3, U266, XG-1 or OPM-2 human myeloma cell lines or patient-derived myeloma cells. At the first signs of morbidity in each tumour group all animals were sacrificed. Tumour load was measured by histological analysis, and bone disease was assessed by micro-CT and standard histomorphometric methods. Mice injected with JJN3, U266 or OPM-2 cells showed high tumour bone marrow infiltration of the long bones with low variability, resulting in osteolytic lesions. In contrast, mice injected with XG-1 or patient-derived myeloma cells showed lower tumour bone marrow infiltration and less bone disease with high variability. Injection of JJN3 cells into NOD/SCID-GAMMA mice resulted in an aggressive, short-term model of myeloma with mice exhibiting signs of morbidity 3 weeks later. Treating these mice with zoledronic acid at the time of tumour cell injection or once tumour was established prevented JJN3-induced bone disease but did not reduce tumour burden, whereas, carfilzomib treatment given once tumour was established significantly reduced tumour burden. Injection of U266, XG-1, OPM-2 and patient-derived myeloma cells resulted in less aggressive longer-term models of myeloma with mice exhibiting signs of morbidity 8 weeks later. Treating U266-induced disease with zoledronic acid prevented the formation of osteolytic lesions and trabecular bone loss as well as reducing tumour burden whereas, carfilzomib treatment only reduced tumour burden. In summary, JJN3, U266 or OPM-2 cells injected into NOD/SCID-GAMMA mice provide robust models to study anti-myeloma therapies, particularly those targeting myeloma bone disease
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses VII. Time delays and the Hubble constant from WFI J2033-4723
Gravitationally lensed quasars can be used to map the mass distribution in
lensing galaxies and to estimate the Hubble constant H0 by measuring the time
delays between the quasar images. Here we report the measurement of two
independent time delays in the quadruply imaged quasar WFI J2033-4723 (z =
1.66). Our data consist of R-band images obtained with the Swiss 1.2 m EULER
telescope located at La Silla and with the 1.3 m SMARTS telescope located at
Cerro Tololo. The light curves have 218 independent epochs spanning 3 full
years of monitoring between March 2004 and May 2007, with a mean temporal
sampling of one observation every 4th day. We measure the time delays using
three different techniques, and we obtain Dt(B-A) = 35.5 +- 1.4 days (3.8%) and
Dt(B-C) = 62.6 +4.1/-2.3 days (+6.5%/-3.7%), where A is a composite of the
close, merging image pair. After correcting for the time delays, we find R-band
flux ratios of F_A/F_B = 2.88 +- 0.04, F_A/F_C = 3.38 +- 0.06, and F_A1/F_A2 =
1.37 +- 0.05 with no evidence for microlensing variability over a time scale of
three years. However, these flux ratios do not agree with those measured in the
quasar emission lines, suggesting that longer term microlensing is present. Our
estimate of H0 agrees with the concordance value: non-parametric modeling of
the lensing galaxy predicts H0 = 67 +13/-10 km s-1 Mpc-1, while the Single
Isothermal Sphere model yields H0 = 63 +7/-3 km s-1 Mpc-1 (68% confidence
level). More complex lens models using a composite de Vaucouleurs plus NFW
galaxy mass profile show twisting of the mass isocontours in the lensing
galaxy, as do the non-parametric models. As all models also require a
significant external shear, this suggests that the lens is a member of the
group of galaxies seen in field of view of WFI J2033-4723.Comment: 14 pages, 12 figures, published in A&
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses VIII. Deconvolution of high resolution near-IR images and simple mass models for 7 gravitationally lensed quasars
We apply the iterative MCS deconvolution method (ISMCS) to near-IR HST
archives data of seven gravitationally lensed quasars currently monitored by
the COSMOGRAIL collaboration: HE 0047-1756, RX J1131-1231, SDSS J1138+0314,
SDSS J1155+6346, SDSS J1226-0006, WFI J2026-4536 and HS 2209+1914. In doing so,
we obtain relative positions for the lensed images and shape parameters for the
light distribution of the lensing galaxy in each system. The lensed image
positions are derived with 1-2 mas accuracy. To predict time delays and to test
the ability of simple mass models to reproduce the observed configuration,
isothermal and de Vaucouleurs mass models are calculated for the whole sample
using state-of-the-art modeling techniques. The effect of the lens environment
on the lens mass models is taken into account with a shear term. Doubly imaged
quasars are equally well fitted by each of these models. A large amount of
shear is necessary to reproduce SDSS J1155+6346 and SDSS J1226-006. In the
latter case, we identify a nearby galaxy as the dominant source of shear. The
quadruply imaged quasar SDSS J1138+0314 is well reproduced by simple lens
models, which is not the case for the two other quads, RX J1131-1231 and WFI
J2026-4536. This might be the signature of astrometric perturbations due to
massive substructures in the lensing galaxy unaccounted for by the models.
Other possible explanations are also presented.Comment: 14 pages, 1 figure (with 28 frames), 5 tables, accepted for
publication in Astronomy & Astrophysics (08/07/2010
The rise of fully turbulent flow
Over a century of research into the origin of turbulence in wallbounded shear
flows has resulted in a puzzling picture in which turbulence appears in a
variety of different states competing with laminar background flow. At slightly
higher speeds the situation changes distinctly and the entire flow is
turbulent. Neither the origin of the different states encountered during
transition, nor their front dynamics, let alone the transformation to full
turbulence could be explained to date. Combining experiments, theory and
computer simulations here we uncover the bifurcation scenario organising the
route to fully turbulent pipe flow and explain the front dynamics of the
different states encountered in the process. Key to resolving this problem is
the interpretation of the flow as a bistable system with nonlinear propagation
(advection) of turbulent fronts. These findings bridge the gap between our
understanding of the onset of turbulence and fully turbulent flows.Comment: 31 pages, 9 figure
TGFβ inhibition stimulates collagen maturation to enhance bone repair and fracture resistance in a murine myeloma model
Multiple myeloma is a plasma cell malignancy that causes debilitating bone disease and fractures, in which TGFβ plays a central role. Current treatments do not repair existing damage and fractures remain a common occurrence. We developed a novel low tumour phase murine model mimicking the plateau phase in patients, as we hypothesized this would be an ideal time to treat with a bone anabolic. Using in vivo microCT we show substantial and rapid bone lesion repair (and prevention) driven by SD‐208 (TGFβ receptor I kinase inhibitor) and chemotherapy (bortezomib and lenalidomide) in mice with human U266‐GFP‐luc myeloma. We discovered that lesion repair occurred via an intramembranous fracture repair‐like mechanism and that SD‐208 enhanced collagen matrix maturation to significantly improve fracture resistance. Lesion healing was associated with VEGFA expression in woven bone, reduced osteocyte‐derived PTHrP, increased osteoblasts, decreased osteoclasts and lower serum TRACP‐5b. SD‐208 also completely prevented bone lesion development mice with aggressive JJN3 tumors, and was more effective than an anti‐TGFβ neutralizing antibody (1D11). We also discovered that SD‐208 promoted osteoblastic differentiation (and overcame the TGFβ‐induced block in osteoblastogenesis) in myeloma patient bone marrow stromal cells in vitro, comparable to normal donors. The improved bone quality and fracture‐resistance with SD‐208 provides incentive for clinical translation to improve myeloma patient quality of life by reducing fracture risk and fatality
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