2,154 research outputs found
Towards Benchmarking Scene Background Initialization
Given a set of images of a scene taken at different times, the availability
of an initial background model that describes the scene without foreground
objects is the prerequisite for a wide range of applications, ranging from
video surveillance to computational photography. Even though several methods
have been proposed for scene background initialization, the lack of a common
groundtruthed dataset and of a common set of metrics makes it difficult to
compare their performance. To move first steps towards an easy and fair
comparison of these methods, we assembled a dataset of sequences frequently
adopted for background initialization, selected or created ground truths for
quantitative evaluation through a selected suite of metrics, and compared
results obtained by some existing methods, making all the material publicly
available.Comment: 6 pages, SBI dataset, SBMI2015 Worksho
Higher-order topological insulators in amorphous solids
We identify the possibility of realizing higher order topological (HOT) phases in noncrystalline or amorphous materials. Starting from two- and three-dimensional crystalline HOT insulators, accommodating topological corner states, we gradually enhance structural randomness in the system. Within a parameter regime, as long as amorphousness is confined by an outer crystalline boundary, the system continues to host corner states, yielding amorphous HOT insulators. However, as structural disorder percolates to the edges, corner states start to dissolve into amorphous bulk, and ultimately the system becomes a trivial insulator when amorphousness plagues the entire system. These outcomes are further substantiated by computing the quadrupolar (octupolar) moment in two (three) dimensions. Therefore, HOT phases can be realized in amorphous solids, when wrapped by a thin (lithographically grown, for example) crystalline layer. Our findings suggest that crystalline topological phases can be realized even in the absence of local crystalline symmetry
Fock space exploration by angle resolved transmission through quantum diffraction grating of cold atoms in an optical lattice
Light transmission or diffraction from different quantum phases of cold atoms
in an optical lattice has recently come up as a useful tool to probe such ultra
cold atomic systems. The periodic nature of the optical lattice potential
closely resembles the structure of a diffraction grating in real space, but
loaded with a strongly correlated quantum many body state which interacts with
the incident electromagnetic wave, a feature that controls the nature of the
light transmission or dispersion through such quantum medium. In this paper we
show that as one varies the relative angle between the cavity mode and the
optical lattice, the peak of the transmission spectrum through such cavity also
changes reflecting the statistical distribution of the atoms in the illuminated
sites. Consequently the angle resolved transmission spectrum of such quantum
diffraction grating can provide a plethora of information about the Fock space
structure of the many body quantum state of ultra cold atoms in such an optical
cavity that can be explored in current state of the art experiments.Comment: 40 double spaced, single column pages, 40 .eps figures, accepted for
publication in Physical Review
Online Partial Service Hosting at the Edge
We consider the problem of service hosting where an application provider can
dynamically rent edge computing resources and serve user requests from the edge
to deliver a better quality of service. A key novelty of this work is that we
allow the service to be hosted partially at the edge which enables a fraction
of the user query to be served by the edge. We model the total cost for
(partially) hosting a service at the edge as a combination of the latency in
serving requests, the bandwidth consumption, and the time-varying cost for
renting edge resources. We propose an online policy called
-RetroRenting (-RR) which dynamically determines the fraction
of the service to be hosted at the edge in any time-slot, based on the history
of the request arrivals and the rent cost sequence. As our main result, we
derive an upper bound on -RR's competitive ratio with respect to the
offline optimal policy that knows the entire request arrival and rent cost
sequence in advance. We conduct extensive numerical evaluations to compare the
performance of -RR with various benchmarks for synthetic and
trace-based request arrival and rent cost processes, and find several parameter
regimes where -RR's ability to store the service partially greatly
improves cost-efficiency
Factors associated with long-term species composition in dry tropical forests of Central India
The long-term future of species composition in forests depends on regeneration. Many factors can affect regeneration, including human use, environmental conditions, and species' traits. This study examines the influence of these factors in a tropical deciduous forest of Central India, which is heavily used by local, forest-dependent residents for livestock grazing, fuel-wood extraction, construction and other livelihood needs. We measure size-class proportions (the ratio of abundance of a species at a site in a higher size class to total abundance in both lower and higher size classes) for 39 tree species across 20 transects at different intensities of human use. The size-class proportions for medium to large trees and for small to medium-sized trees were negatively associated with species that are used for local construction, while size class proportions for saplings to small trees were positively associated with those species that are fire resistant and negatively associated with livestock density. Results indicate that grazing and fire prevent non-fire resistant species from reaching reproductive age, which can alter the long term composition and future availability of species that are important for local use and ecosystem services. Management efforts to reduce fire and forest grazing could reverse these impacts on long-term forest composition
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Fused Deposition of Ceramics (FDC) for Structural Silicon Nitride Components
Fused Deposition of Ceramics is aI! SFF tec~que based on comm~rcial FDMTM ~echno.logy, f?r
fabrication of structural and functIonal cerannc components. ThIS study descnbes, ill detail,
process improvements made in pre-FDC, FDC, and post-FDC fabrication steps to achieve
functional properties in commercial GS-44 silicon nitride ?omponents. . Microstructural
characterization of sintered FDC parts reveals microstructures simllar to convennonally processed
silicon nitride material. Mechanical properties of FDC processed silicon nitride bend bars and
toughness samples were evaluated. These property evaluation studies demonstrate that mechanical
properties similar to commercial GS-44 silicon nitride materials can be achieved using FDC. The
study also describes results achieved on fabrication of complex components from silicon nitride
using FDC.Mechanical Engineerin
Identification and management of atherosclerotic cardiovascular disease risk in south Asian populations in the U.S.
South Asians (SAs, individuals with ancestry from Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka) are among the fastest growing ethnic subgroups in the United States. SAs typically experience a high prevalence of diabetes, abdominal obesity, and hypertension, among other cardiovascular disease risk factors, which are often under recognized and undermanaged. The excess coronary heart disease risk in this growing population must be critically assessed and managed with culturally appropriate preventive services. Accordingly, this scientific document prepared by a multidisciplinary group of clinicians and investigators in cardiology, internal medicine, pharmacy, and SA-centric researchers describes key characteristics of traditional and nontraditional cardiovascular disease risk factors, compares and contrasts available risk assessment tools, discusses the role of blood-based biomarkers and coronary artery calcium to enhance risk assessment and prevention strategies, and provides evidenced-based approaches and interventions that may reduce coronary heart disease disparities in this higher-risk population
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Structural Ceramics by Fused Deposition of Ceramics
Fused Deposition of Ceramics (FDC) is a SFF technique, based on FDMTM technology, for
fabrication of advanced structural ceramics from powderlbinder filaments. In this study, in-situ
reinforced (ISR) Si3N4 powder and polymer/wax based binder systems were used as filament
material for FDC processing using a commercially available FDMTM system, 3D Modeler.
Powderlbinder feedstocks were mixed using a torque rheometer and filaments were fabricated
using a capillary rheometer and twin screw extruder. Green FDC components were built from
these filaments and then characterized for inter-road and inter-layer bonding. Binder removal
procedures were established for FDC green components to yield brown parts without distortion or
shape change. Brown FDC parts were characterized for carbon residue, pore distribution and
dimensional changes. Brown FDC parts were then sintered and the sintered density,
microstructure, and shrinkage anisotropy were studied.Mechanical Engineerin
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