8,830 research outputs found
Systematics of black hole binary inspiral kicks and the slowness approximation
During the inspiral and merger of black holes, the interaction of
gravitational wave multipoles carries linear momentum away, thereby providing
an astrophysically important recoil, or "kick" to the system and to the final
black hole remnant. It has been found that linear momentum during the last
stage (quasinormal ringing) of the collapse tends to provide an "antikick" that
in some cases cancels almost all the kick from the earlier (quasicircular
inspiral) emission. We show here that this cancellation is not due to
peculiarities of gravitational waves, black holes, or interacting multipoles,
but simply to the fact that the rotating flux of momentum changes its intensity
slowly. We show furthermore that an understanding of the systematics of the
emission allows good estimates of the net kick for numerical simulations
started at fairly late times, and is useful for understanding qualitatively
what kinds of systems provide large and small net kicks.Comment: 15 pages, 6 figures, 2 table
Black hole binary inspiral and trajectory dominance
Gravitational waves emitted during the inspiral, plunge and merger of a black
hole binary carry linear momentum. This results in an astrophysically important
recoil to the final merged black hole, a ``kick'' that can eject it from the
nucleus of a galaxy. In a previous paper we showed that the puzzling partial
cancellation of an early kick by a late antikick, and the dependence of the
cancellation on black hole spin, can be understood from the phenomenology of
the linear momentum waveforms. Here we connect that phenomenology to its
underlying cause, the spin-dependence of the inspiral trajectories. This
insight suggests that the details of plunge can be understood more broadly with
a focus on inspiral trajectories.Comment: 15 pages, 12 figure
Bleeding Kansas: Contested Liberty in the Civil War Era
Cowboy democracy Forming a state out of a divided people Nicole Etcheson\u27s new work, Bleeding Kansas: Contested Liberty in the Civil War Era, could have been a great book; instead it is merely a good one. Today, both Kansas and the United States stand on the threshold of ...
Sherlock: Scalable Fact Learning in Images
We study scalable and uniform understanding of facts in images. Existing
visual recognition systems are typically modeled differently for each fact type
such as objects, actions, and interactions. We propose a setting where all
these facts can be modeled simultaneously with a capacity to understand
unbounded number of facts in a structured way. The training data comes as
structured facts in images, including (1) objects (e.g., ), (3) actions (e.g., ). Each fact has a semantic
language view (e.g., ) and a visual view (an image with this
fact). We show that learning visual facts in a structured way enables not only
a uniform but also generalizable visual understanding. We propose and
investigate recent and strong approaches from the multiview learning literature
and also introduce two learning representation models as potential baselines.
We applied the investigated methods on several datasets that we augmented with
structured facts and a large scale dataset of more than 202,000 facts and
814,000 images. Our experiments show the advantage of relating facts by the
structure by the proposed models compared to the designed baselines on
bidirectional fact retrieval.Comment: Jan 7 Updat
Deep GrabCut for Object Selection
Most previous bounding-box-based segmentation methods assume the bounding box
tightly covers the object of interest. However it is common that a rectangle
input could be too large or too small. In this paper, we propose a novel
segmentation approach that uses a rectangle as a soft constraint by
transforming it into an Euclidean distance map. A convolutional encoder-decoder
network is trained end-to-end by concatenating images with these distance maps
as inputs and predicting the object masks as outputs. Our approach gets
accurate segmentation results given sloppy rectangles while being general for
both interactive segmentation and instance segmentation. We show our network
extends to curve-based input without retraining. We further apply our network
to instance-level semantic segmentation and resolve any overlap using a
conditional random field. Experiments on benchmark datasets demonstrate the
effectiveness of the proposed approaches.Comment: BMVC 201
Coulomb drag, mesoscopic physics, and electron-electron interaction.
The first part of this thesis deals with the study of mesoscopic fluctuations of the Coulomb drag resistance in double-layer GaAs/AlGaAs heterostructures, both in weak magnetic fields and strong magnetic fields. In the second part, measurements are made in a monolayer graphene structure, specifically of the quantum lifetime, and the mesoscopic resistance fluctuations at quantising magnetic fields
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