4,180 research outputs found
Asymmetric Totally-corrective Boosting for Real-time Object Detection
Real-time object detection is one of the core problems in computer vision.
The cascade boosting framework proposed by Viola and Jones has become the
standard for this problem. In this framework, the learning goal for each node
is asymmetric, which is required to achieve a high detection rate and a
moderate false positive rate. We develop new boosting algorithms to address
this asymmetric learning problem. We show that our methods explicitly optimize
asymmetric loss objectives in a totally corrective fashion. The methods are
totally corrective in the sense that the coefficients of all selected weak
classifiers are updated at each iteration. In contract, conventional boosting
like AdaBoost is stage-wise in that only the current weak classifier's
coefficient is updated. At the heart of the totally corrective boosting is the
column generation technique. Experiments on face detection show that our
methods outperform the state-of-the-art asymmetric boosting methods.Comment: 14 pages, published in Asian Conf. Computer Vision 201
Face Detection with Effective Feature Extraction
There is an abundant literature on face detection due to its important role
in many vision applications. Since Viola and Jones proposed the first real-time
AdaBoost based face detector, Haar-like features have been adopted as the
method of choice for frontal face detection. In this work, we show that simple
features other than Haar-like features can also be applied for training an
effective face detector. Since, single feature is not discriminative enough to
separate faces from difficult non-faces, we further improve the generalization
performance of our simple features by introducing feature co-occurrences. We
demonstrate that our proposed features yield a performance improvement compared
to Haar-like features. In addition, our findings indicate that features play a
crucial role in the ability of the system to generalize.Comment: 7 pages. Conference version published in Asian Conf. Comp. Vision
201
Generation and propagation of entanglement in driven coupled-qubit systems
In a bipartite system subject to decoherence from two separate reservoirs,
the entanglement is typically destroyed faster than for single reservoirs.
Surprisingly however, the existence of separate reservoirs can also have a
beneficial entangling effect: if the qubits are coupled and driven externally
by a classical field, the system ends up in a stationary state characterized by
a finite degree of entanglement. This phenomenon occurs only in a certain
region of the parameter space and the structure of the stationary state has a
universal form which does not depend on the initial state or on the specific
physical realization of the qubits. We show that the entanglement thus
generated can be propagated within a quantum network using simple local unitary
operations. We suggest the use of such systems as "batteries of entanglement"
in quantum circuits.Comment: 14 pages, 7 figure
Feature-based interference from unattended visual field during attentional tracking in younger and older adults
The ability to attend to multiple objects that move in the visual field is
important for many aspects of daily functioning. The attentional capacity for
such dynamic tracking, however, is highly limited and undergoes age-related
decline. Several aspects of the tracking process can influence performance.
Here, we investigated effects of feature-based interference from distractor
objects that appear in unattended regions of the visual field with a
hemifield-tracking task. Younger and older participants performed an
attentional tracking task in one hemifield while distractor objects were
concurrently presented in the unattended hemifield. Feature similarity between
objects in the attended and unattended hemifields as well as motion speed and
the number of to-be-tracked objects were parametrically manipulated. The
results show that increasing feature overlap leads to greater interference
from the unattended visual field. This effect of feature-based interference
was only present in the slow speed condition, indicating that the interference
is mainly modulated by perceptual demands. High-performing older adults showed
a similar interference effect as younger adults, whereas low-performing adults
showed poor tracking performance overall
Adhesion mechanics of graphene membranes
The interaction of graphene with neighboring materials and structures plays
an important role in its behavior, both scientifically and technologically. The
interactions are complicated due to the interplay between surface forces and
possibly nonlinear elastic behavior. Here we review recent experimental and
theoretical advances in the understanding of graphene adhesion. We organize our
discussion into experimental and theoretical efforts directed toward: graphene
conformation to a substrate, determination of adhesion energy, and applications
where graphene adhesion plays an important role. We conclude with a brief
prospectus outlining open issues.Comment: Review article to appear in special issue on graphene in Solid State
Communication
Diverse viruses in deep-sea hydrothermal vent fluids have restricted dispersal across ocean basins
© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Thomas, E., Anderson, R. E., Li, V., Rogan, L. J., & Huber, J. A. Diverse viruses in deep-sea hydrothermal vent fluids have restricted dispersal across ocean basins. Msystems, 6(3), (2021): e00068-21, https://doi.org/10.1128/mSystems.00068-21.In the ocean, viruses impact microbial mortality, regulate biogeochemical cycling, and alter the metabolic potential of microbial lineages. At deep-sea hydrothermal vents, abundant viruses infect a wide range of hosts among the archaea and bacteria that inhabit these dynamic habitats. However, little is known about viral diversity, host range, and biogeography across different vent ecosystems, which has important implications for how viruses manipulate microbial function and evolution. Here, we examined viral diversity, viral and host distribution, and virus-host interactions in microbial metagenomes generated from venting fluids from several vent sites within three different geochemically and geographically distinct hydrothermal systems: Piccard and Von Damm vent fields at the Mid-Cayman Rise in the Caribbean Sea, and at several vent sites within Axial Seamount in the Pacific Ocean. Analysis of viral sequences and clustered regularly interspaced short palindromic repeat (CRISPR) spacers revealed highly diverse viral assemblages and evidence of active infection. Network analysis revealed that viral host range was relatively narrow, with very few viruses infecting multiple microbial lineages. Viruses were largely endemic to individual vent sites, indicating restricted dispersal, and in some cases, viral assemblages persisted over time. Thus, we show that hydrothermal vent fluids are home to novel, diverse viral assemblages that are highly localized to specific regions and taxa.Funding for E.T. was provided by Carleton College. R.E.A. was supported by a NASA Postdoctoral Fellowship with the NASA Astrobiology Institute. This work was supported by a NASA Exobiology grant 80NSSC18K1076 to R.E.A. and J.A.H., a NASA Astrobiology Science and Technology for Exploring Planets (ASTEP) grant NNX-327 09AB75G, and a grant from Deep Carbon Observatory's Deep Life Initiative to J.A.H., the NSF Science and Technology Center for Dark Energy Biosphere Investigations (C-DEBI) to J.A.H., and the Gordon and Betty Moore Foundation grant GBMF3297 to J.A.H. Samples were collected from the Mid-Cayman Rise with the assistance of the captains and crew of the R/V Atlantis and R/V Falkor as well as ROVs Jason and Nereus. For Mid-Cayman Rise, ship and vehicle time in 2012 were supported by the NSF-OCE grant OCE-1061863 to Chris German and Jeff Seewald and in 2013 by the Schmidt Ocean Institute during cruise FX008-2013 aboard the R/V Falkor. Samples collected from Axial Seamount were collected with the assistance of the captains and crew of the R/V Falkor, R/V Thompson, and R/V Brown as well as the ROV ROPOS and Jason groups, and in 2013 the Schmidt Ocean Institute during cruise FK010-2013 aboard the R/V Falkor
Adiabatic evolution under quantum control
One of the difficulties in adiabatic quantum computation is the limit on the
computation time. Here we propose two schemes to speed-up the adiabatic
evolution. To apply this controlled adiabatic evolution to adiabatic quantum
computation, we design one of the schemes without any prior knowledge of the
instantaneous eigenstates of the final Hamiltonian. Whereas in another scheme,
the control is constructed with the instantaneous eigenstate that is the target
state of the control. As an illustration, we study a two-level system driven by
a time-dependent magnetic field under the control. The physics behind the
control scheme is explained.Comment: 5 pages, 3 figure
RNA-Mediated Gene Silencing Signals Are Not Graft Transmissible from the Rootstock to the Scion in Greenhouse-Grown Apple Plants Malus sp.
RNA silencing describes the sequence specific degradation of RNA targets. Silencing is a non-cell autonomous event that is graft transmissible in different plant species. The present study is the first report on systemic acquired dsRNA-mediated gene silencing of transgenic and endogenous gene sequences in a woody plant like apple. Transgenic apple plants overexpressing a hairpin gene construct of the gusA reporter gene were produced. These plants were used as rootstocks and grafted with scions of the gusA overexpressing transgenic apple clone T355. After grafting, we observed a reduction of the gusA gene expression in T355 scions in vitro, but not in T355 scions grown in the greenhouse. Similar results were obtained after silencing of the endogenous Mdans gene in apple that is responsible for anthocyanin biosynthesis. Subsequently, we performed grafting experiments with Mdans silenced rootstocks and red leaf scions of TNR31-35 in order to evaluate graft transmitted silencing of the endogenous Mdans. The results obtained suggested a graft transmission of silencing signals in in vitro shoots. In contrast, no graft transmission of dsRNA-mediated gene silencing signals was detectable in greenhouse-grown plants and in plants grown in an insect protection tent
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