21,766 research outputs found
Development of a front end ASIC for Dark Matter directional detection with MIMAC
A front end ASIC (BiCMOS-SiGe 0.35 \mum) has been developed within the
framework of the MIMAC detector project, which aims at directional detection of
non-baryonic Dark Matter. This search strategy requires 3D reconstruction of
low energy (a few keV) tracks with a gaseous \muTPC. The development of this
front end ASIC is a key point of the project, allowing the 3D track
reconstruction. Each ASIC monitors 16 strips of pixels with charge
preamplifiers and their time over threshold is provided in real time by current
discriminators via two serializing LVDS links working at 320 MHz. The charge is
summed over the 16 strips and provided via a shaper. These specifications have
been chosen in order to build an auto triggered electronics. An acquisition
board and the related software were developed in order to validate this
methodology on a prototype chamber. The prototype detector presents an anode
where 2 x 96 strips of pixels are monitored.Comment: 12 pages, 10 figure
Weak Lensing of Intensity Mapping: the Cosmic Infrared Background
Gravitational lensing deflects the paths of cosmic infrared background (CIB)
photons, leaving a measurable imprint on CIB maps. The resulting statistical
anisotropy can be used to reconstruct the matter distribution out to the
redshifts of CIB sources. To this end, we generalize the CMB lensing quadratic
estimator to any weakly non-Gaussian source field, by deriving the optimal
lensing weights. We point out the additional noise and bias caused by the
non-Gaussianity and the `self-lensing' of the source field. We propose methods
to reduce, subtract or model these non-Gaussianities. We show that CIB lensing
should be detectable with Planck data, and detectable at high significance for
future CMB experiments like CCAT-Prime. The CIB thus constitutes a new source
image for lensing studies, providing constraints on the amplitude of structure
at intermediate redshifts between galaxies and the CMB. CIB lensing
measurements will also give valuable information on the star formation history
in the universe, constraining CIB halo models beyond the CIB power spectrum. By
laying out a detailed treatment of lens reconstruction from a weakly
non-Gaussian source field, this work constitutes a stepping stone towards lens
reconstruction from continuum or line intensity mapping data, such as the
Lyman-alpha emission, absorption, and the 21cm radiation.Comment: Accepted in Physical Review
Weak lensing reconstruction through cosmic magnification I: a minimal variance map reconstruction
We present a concept study on weak lensing map reconstruction through the
cosmic magnification effect in galaxy number density distribution. We propose a
minimal variance linear estimator to minimize both the dominant systematical
and statistical errors in the map reconstruction. It utilizes the distinctively
different flux dependences to separate the cosmic magnification signal from the
overwhelming galaxy intrinsic clustering noise. It also minimizes the shot
noise error by an optimal weighting scheme on the galaxy number density in each
flux bin. Our method is in principle applicable to all galaxy surveys with
reasonable redshift information. We demonstrate its applicability against the
planned Square Kilometer Array survey, under simplified conditions. Weak
lensing maps reconstructed through our method are complementary to that from
cosmic shear and CMB and 21cm lensing. They are useful for cross checking over
systematical errors in weak lensing reconstruction and for improving
cosmological constraints.Comment: 12 pages, 9 figures, published in MNRA
Neural Face Editing with Intrinsic Image Disentangling
Traditional face editing methods often require a number of sophisticated and
task specific algorithms to be applied one after the other --- a process that
is tedious, fragile, and computationally intensive. In this paper, we propose
an end-to-end generative adversarial network that infers a face-specific
disentangled representation of intrinsic face properties, including shape (i.e.
normals), albedo, and lighting, and an alpha matte. We show that this network
can be trained on "in-the-wild" images by incorporating an in-network
physically-based image formation module and appropriate loss functions. Our
disentangling latent representation allows for semantically relevant edits,
where one aspect of facial appearance can be manipulated while keeping
orthogonal properties fixed, and we demonstrate its use for a number of facial
editing applications.Comment: CVPR 2017 ora
Automated 3D quantitative assessment and measurement of alpha angles from the femoral head-neck junction using MR imaging
To develop an automated approach for 3D quantitative assessment and measurement of alpha angles from the femoral head-neck (FHN) junction using bone models derived from magnetic resonance (MR) images of the hip joint
Autonomous Tissue Scanning under Free-Form Motion for Intraoperative Tissue Characterisation
In Minimally Invasive Surgery (MIS), tissue scanning with imaging probes is
required for subsurface visualisation to characterise the state of the tissue.
However, scanning of large tissue surfaces in the presence of deformation is a
challenging task for the surgeon. Recently, robot-assisted local tissue
scanning has been investigated for motion stabilisation of imaging probes to
facilitate the capturing of good quality images and reduce the surgeon's
cognitive load. Nonetheless, these approaches require the tissue surface to be
static or deform with periodic motion. To eliminate these assumptions, we
propose a visual servoing framework for autonomous tissue scanning, able to
deal with free-form tissue deformation. The 3D structure of the surgical scene
is recovered and a feature-based method is proposed to estimate the motion of
the tissue in real-time. A desired scanning trajectory is manually defined on a
reference frame and continuously updated using projective geometry to follow
the tissue motion and control the movement of the robotic arm. The advantage of
the proposed method is that it does not require the learning of the tissue
motion prior to scanning and can deal with free-form deformation. We deployed
this framework on the da Vinci surgical robot using the da Vinci Research Kit
(dVRK) for Ultrasound tissue scanning. Since the framework does not rely on
information from the Ultrasound data, it can be easily extended to other
probe-based imaging modalities.Comment: 7 pages, 5 figures, ICRA 202
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