Search results for "methods [Diffusion Tensor Imaging]"
showing 10 items of 992 documents
An optical pulse modulator based on an all-fibre mirror
1996
In this article we present an all-fiber Sagnac interferometer modulated in a pulsed regime.
Reliable Planar Object Pose Estimation in Light Fields From Best Subaperture Camera Pairs
2018
International audience; A light-field camera can obtain richer information about a scene than a usual camera. This property offers a lot of potential for robot vision. In this paper, we present a method for pose estimation of a planar object with a light-field camera. The light-field camera can be regarded as a set of sub-aperture cameras. Although any combination of them can theoretically be used for the pose estimation, the accuracy depends on the combination. We show that the estimated pose error can be reduced by selecting the best pair of sub-aperture cameras. We have evaluated the accuracy of our approach with real experiments using a light-field camera in front of planar targets held…
What causes the large extensions of red-supergiant atmospheres? Comparisons of interferometric observations with 1-D hydrostatic, 3-D convection, and…
2015
We present the atmospheric structure and the fundamental parameters of three red supergiants, increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. We carried out spectro-interferometric observations of 3 RSGs in the near-infrared K-band with the VLTI/AMBER instrument at medium spectral resolution. To comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3-D convection, and new 1-D self-excited pulsation models of RSGs. Our near-infrared flux spectra are well reproduced by the P…
Structural variability of 3C 111 on parsec scales
2011
We discuss the parsec-scale structural variability of the extragalactic jet 3C 111 related to a major radio flux density outburst in 2007. The data analyzed were taken within the scope of the MOJAVE, UMRAO, and F-GAMMA programs, which monitor a large sample of the radio brightest compact extragalactic jets with the VLBA, the University of Michigan 26 m, the Effelsberg 100 m, and the IRAM 30 m radio telescopes. The analysis of the VLBA data is performed by fitting Gaussian model components in the visibility domain. We associate the ejection of bright features in the radio jet with a major flux-density outburst in 2007. The evolution of these features suggests the formation of a leading compo…
Studies of Relativistic Jets in Active Galactic Nuclei with SKA
2014
Relativistic jets in active galactic nuclei (AGN) are among the most powerful astrophysical objects discovered to date. Indeed, jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004). Most of the fundamental questions about the physics of relativistic jets still remain unanswered, and await high-sensitivity radio instruments such as SKA to solve them. These questions will be addressed specially through analysis of the massive data sets arising from the deep, all-sky surveys (both total and polarimetric flux) from SKA1. Wide-field very-long-baseline-interferometri…
Scheduling in Targeted Transient Surveys and a New Telescope for CHASE
2010
We present a method for scheduling observations in small field-of-view transient targeted surveys. The method is based on maximizing the probability of detection of transient events of a given type and age since occurrence; it requires knowledge of the time since the last observation for every observed field, the expected light curve of the event, and the expected rate of events in the fields where the search is performed. In order to test this scheduling strategy we use a modified version of the genetic scheduler developed for the telescope control system RTS2. In particular, we present example schedules designed for a future 50 cm telescope that will expand the capabilities of the CHASE s…
Euclid preparation XV. Forecasting cosmological constraints for the Euclid and CMB joint analysis
2022
The combination and cross-correlation of the upcoming $Euclid$ data with cosmic microwave background (CMB) measurements is a source of great expectation since it will provide the largest lever arm of epochs, ranging from recombination to structure formation across the entire past light cone. In this work, we present forecasts for the joint analysis of $Euclid$ and CMB data on the cosmological parameters of the standard cosmological model and some of its extensions. This work expands and complements the recently published forecasts based on $Euclid$-specific probes, namely galaxy clustering, weak lensing, and their cross-correlation. With some assumptions on the specifications of current and…
Searching for sterile neutrino with X-ray intensity mapping
2019
The cosmological X-ray emission associated to the possible radiative decay of sterile neutrinos is composed by a collection of lines at different energies. For a given mass, each line corresponds to a given redshift. In this work, we cross correlate such line emission with catalogs of galaxies tracing the dark matter distribution at different redshifts. We derive observational prospects by correlating the X-ray sky that will be probed by the eROSITA and Athena missions with current and near future photometric and spectroscopic galaxy surveys. A relevant and unexplored fraction of the parameter space of sterile neutrinos can be probed by this technique.
Euclid Preparation. XIV. The Complete Calibration of the Color–Redshift Relation (C3R2) Survey: Data Release 3
2021
Stanford, S. A., et al.
Limits on spin-dependent WIMP-nucleon cross sections from 225 live days of XENON100 data
2013
We present new experimental constraints on the elastic, spin-dependent WIMP-nucleon cross section using recent data from the XENON100 experiment, operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 224.6 live days x 34 kg of exposure acquired during 2011 and 2012 revealed no excess signal due to axial-vector WIMP interactions with 129-Xe and 131-Xe nuclei. This leads to the most stringent upper limits on WIMP-neutron cross sections for WIMP masses above 6 GeV, with a minimum cross section of 3.5 x 10^{-40} cm^2 at a WIMP mass of 45 GeV, at 90% confidence level.