7,013 research outputs found
See the Difference: Direct Pre-Image Reconstruction and Pose Estimation by Differentiating HOG
The Histogram of Oriented Gradient (HOG) descriptor has led to many advances
in computer vision over the last decade and is still part of many state of the
art approaches. We realize that the associated feature computation is piecewise
differentiable and therefore many pipelines which build on HOG can be made
differentiable. This lends to advanced introspection as well as opportunities
for end-to-end optimization. We present our implementation of HOG based
on the auto-differentiation toolbox Chumpy and show applications to pre-image
visualization and pose estimation which extends the existing differentiable
renderer OpenDR pipeline. Both applications improve on the respective
state-of-the-art HOG approaches
Highly efficient interfacing of guided plasmons and photons in nanowires
Successful exploitations of strongly confined surface plasmon-polaritons
critically rely on their efficient and rapid conversion to lossless channels.
We demonstrate a simple, robust, and broad-band butt-coupling technique for
connecting a metallic nanowire and a dielectric nanofiber. Conversion
efficiencies above 95% in the visible and close to 100% in the near infrared
can be achieved with realistic parameters. Moreover, by combining butt-coupling
with nanofocusing, we propose a broad-band high-throughput near-field optical
microscope.Comment: 5 figure
Coherent interaction of a metallic structure with a single quantum emitter: from super absorption to cloaking
We provide a general theoretical platform based on quantized radiation in
absorptive and inhomogeneous media for investigating the coherent interaction
of light with metallic structures in the immediate vicinity of quantum
emitters. In the case of a very small metallic cluster, we demonstrate extreme
regimes where a single emitter can either counteract or enhance particle
absorption by three orders of magnitude. For larger structures, we show that an
emitter can eliminate both scattering and absorption and cloak a plasmonic
antenna. We provide physical interpretations of our results and discuss their
applications in active metamaterials and quantum plasmonics
Quantum Experiments and Graphs III: High-Dimensional and Multi-Particle Entanglement
Quantum entanglement plays an important role in quantum information
processes, such as quantum computation and quantum communication. Experiments
in laboratories are unquestionably crucial to increase our understanding of
quantum systems and inspire new insights into future applications. However,
there are no general recipes for the creation of arbitrary quantum states with
many particles entangled in high dimensions. Here, we exploit a recent
connection between quantum experiments and graph theory and answer this
question for a plethora of classes of entangled states. We find experimental
setups for Greenberger-Horne-Zeilinger states, W states, general Dicke states,
and asymmetrically high-dimensional multipartite entangled states. This result
sheds light on the producibility of arbitrary quantum states using photonic
technology with probabilistic pair sources and allows us to understand the
underlying technological and fundamental properties of entanglement.Comment: 7 pages, 7 figures; Appendix 3 pages, 5 figure
Effects of Insurance on Farmer Crop Abandonment
Empirical evidence for the existence of moral hazard in the U.S. crop insurance program has been inconclusive. Here, we seek empirical evidence of moral hazard in the U.S. crop insurance program, departing from the established empirical literature in two significant respects. First, we attempt to uncover evidence of moral hazard by examining the effects of crop insurance on post-planting crop abandonment decisions. Second, we expand to the scope of existing empirical studies by including regions and crops that have historically experienced high loss ratios under the Federal crop insurance program. Our results provide strong evidence that insurance participation encourages producers to abandon their crops during the growing season for corn in Central Plains and Southern Plains regions and for upland cotton in Southeast, Delta States and Southern Plains regions.Farm Management, Risk and Uncertainty,
MODELING MULTIVARIATE CROP YIELD DENSITIES WITH FREQUENT EXTREME EVENTS
Measuring the lower tail of a crop yield distribution is important for managing agricultural production risk and rating crop insurance. Common parametric techniques encounter difficulties when attempting to model extreme yield events. We evaluate and compare alternative models based on our candidate distributions for high risk counties.Research Methods/ Statistical Methods,
On Heterogeneous Neighbor Discovery in Wireless Sensor Networks
Neighbor discovery plays a crucial role in the formation of wireless sensor
networks and mobile networks where the power of sensors (or mobile devices) is
constrained. Due to the difficulty of clock synchronization, many asynchronous
protocols based on wake-up scheduling have been developed over the years in
order to enable timely neighbor discovery between neighboring sensors while
saving energy. However, existing protocols are not fine-grained enough to
support all heterogeneous battery duty cycles, which can lead to a more rapid
deterioration of long-term battery health for those without support. Existing
research can be broadly divided into two categories according to their
neighbor-discovery techniques---the quorum based protocols and the co-primality
based protocols.In this paper, we propose two neighbor discovery protocols,
called Hedis and Todis, that optimize the duty cycle granularity of quorum and
co-primality based protocols respectively, by enabling the finest-grained
control of heterogeneous duty cycles. We compare the two optimal protocols via
analytical and simulation results, which show that although the optimal
co-primality based protocol (Todis) is simpler in its design, the optimal
quorum based protocol (Hedis) has a better performance since it has a lower
relative error rate and smaller discovery delay, while still allowing the
sensor nodes to wake up at a more infrequent rate.Comment: Accepted by IEEE INFOCOM 201
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