952 research outputs found
A Weakly Supervised Approach for Estimating Spatial Density Functions from High-Resolution Satellite Imagery
We propose a neural network component, the regional aggregation layer, that
makes it possible to train a pixel-level density estimator using only
coarse-grained density aggregates, which reflect the number of objects in an
image region. Our approach is simple to use and does not require
domain-specific assumptions about the nature of the density function. We
evaluate our approach on several synthetic datasets. In addition, we use this
approach to learn to estimate high-resolution population and housing density
from satellite imagery. In all cases, we find that our approach results in
better density estimates than a commonly used baseline. We also show how our
housing density estimator can be used to classify buildings as residential or
non-residential.Comment: 10 pages, 8 figures. ACM SIGSPATIAL 2018, Seattle, US
Galaxy number-count dipole and superhorizon fluctuations
In view of the growing tension between the dipole anisotropy of number counts of cosmologically distant sources and of the cosmic microwave background (CMB), we investigate the number count dipole induced by primordial perturbations with wavelength comparable to or exceeding the Hubble radius today. First, we find that neither adiabatic nor isocurvature superhorizon modes can generate an intrinsic number count dipole. However a superhorizon isocurvature mode does induce a relative velocity between the CMB and the (dark) matter rest frames and thereby affects the CMB dipole. We revisit the possibility that it has an intrinsic component due to such a mode, thus enabling consistency with the galaxy number count dipole if the latter is actually kinematic in origin. Although this scenario is not particularly natural, there are possible links with other anomalies and it predicts a concommitant galaxy number count quadrupole which may be measurable in future surveys. We also investigate the number count dipole induced by modes smaller than the Hubble radius, finding that subject to CMB constraints this is too small to reconcile the dipole tension
A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 AU
Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).Our nearest neighbor, Proxima Centauri, hosts a temperate terrestrial planet. We detected in radial velocities evidence of a possible second planet with minimum mass m c sin i c = 5.8 ± 1.9 M ⊕ and orbital period P c = 5.21 - 0.22 + 0.26 years. The analysis of photometric data and spectro-scopic activity diagnostics does not explain the signal in terms of a stellar activity cycle, but follow-up is required in the coming years for confirming its planetary origin. We show that the existence of the planet can be ascertained, and its true mass can be determined with high accuracy, by combining Gaia astrometry and radial velocities. Proxima c could become a prime target for follow-up and characterization with next-generation direct imaging instrumentation due to the large maximum angular separation of ~1 arc second from the parent star. The candidate planet represents a challenge for the models of super-Earth formation and evolution.Peer reviewedFinal Published versio
First-line trifluridine/tipiracil + bevacizumab in patients with unresectable metastatic colorectal cancer: final survival analysis in the TASCO1 study
Colorectal cancerCà ncer de còlonCáncer de colonBackground
Therapeutic options are limited in patients with unresectable metastatic colorectal cancer (mCRC) ineligible for intensive chemotherapy. The use of trifluridine/tipiracil plus bevacizumab (TT-B) in this setting was evaluated in the TASCO1 trial; here, we present the final overall survival (OS) results.
Methods
TASCO1 was an open-label, non-comparative phase II trial. Patients (n = 153) were randomised 1:1 to TT-B (trifluridine/tipiracil 35 mg/m2 orally twice daily on days 1–5 and 8–12, and bevacizumab intravenously 5 mg/kg on days 1 and 15 of each 28-day cycle) or capecitabine plus bevacizumab (C-B; capecitabine, 1250 mg/m2 orally twice daily on days 1–14 and bevacizumab 7.5 mg/kg intravenously on day 1 of each 21-day cycle). Final OS was analysed when all patients had either died or withdrawn from the study. Adjusted multivariate regression was used to investigate the effects of pre-specified variables on OS.
Results
At 1 September 2020, median OS was 22.3 months (95% CI: 18.0–23.7) with TT-B and 17.7 months (95% CI: 12.6–19.8) with C-B (adjusted HR 0.78; 95% CI: 0.55–1.10). No variables negatively affected OS with TT-B. Safety results were consistent with prior findings.
Conclusions
TT-B is a promising therapeutic regimen in mCRC patients ineligible for intensive chemotherapy.This study was funded by Servier and Taiho
The Carnegie Astrometric Planet Search Program
We are undertaking an astrometric search for gas giant planets and brown
dwarfs orbiting nearby low mass dwarf stars with the 2.5-m du Pont telescope at
the Las Campanas Observatory in Chile. We have built two specialized
astrometric cameras, the Carnegie Astrometric Planet Search Cameras (CAPSCam-S
and CAPSCam-N), using two Teledyne Hawaii-2RG HyViSI arrays, with the cameras'
design having been optimized for high accuracy astrometry of M dwarf stars. We
describe two independent CAPSCam data reduction approaches and present a
detailed analysis of the observations to date of one of our target stars, NLTT
48256. Observations of NLTT 48256 taken since July 2007 with CAPSCam-S imply
that astrometric accuracies of around 0.3 milliarcsec per hour are achievable,
sufficient to detect a Jupiter-mass companion orbiting 1 AU from a late M dwarf
10 pc away with a signal-to-noise ratio of about 4. We plan to follow about 100
nearby (primarily within about 10 pc) low mass stars, principally late M, L,
and T dwarfs, for 10 years or more, in order to detect very low mass companions
with orbital periods long enough to permit the existence of habitable,
Earth-like planets on shorter-period orbits. These stars are generally too
faint and red to be included in ground-based Doppler planet surveys, which are
often optimized for FGK dwarfs. The smaller masses of late M dwarfs also yield
correspondingly larger astrometric signals for a given mass planet. Our search
will help to determine whether gas giant planets form primarily by core
accretion or by disk instability around late M dwarf stars.Comment: 48 pages, 9 figures. in press, Publ. Astron. Soc. Pacifi
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