55,479 research outputs found
Reference face graph for face recognition
Face recognition has been studied extensively; however, real-world face recognition still remains a challenging task. The demand for unconstrained practical face recognition is rising with the explosion of online multimedia such as social networks, and video surveillance footage where face analysis is of significant importance. In this paper, we approach face recognition in the context of graph theory. We recognize an unknown face using an external reference face graph (RFG). An RFG is generated and recognition of a given face is achieved by comparing it to the faces in the constructed RFG. Centrality measures are utilized to identify distinctive faces in the reference face graph. The proposed RFG-based face recognition algorithm is robust to the changes in pose and it is also alignment free. The RFG recognition is used in conjunction with DCT locality sensitive hashing for efficient retrieval to ensure scalability. Experiments are conducted on several publicly available databases and the results show that the proposed approach outperforms the state-of-the-art methods without any preprocessing necessities such as face alignment. Due to the richness in the reference set construction, the proposed method can also handle illumination and expression variation
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Zapping index: Using smile to measure advertisement zapping likelihood
In marketing and advertising research, 'zapping' is defined as the action when a viewer stops watching a commercial. Researchers analyze users' behavior in order to prevent zapping which helps advertisers to design effective commercials. Since emotions can be used to engage consumers, in this paper, we leverage automated facial expression analysis to understand consumers' zapping behavior. Firstly, we provide an accurate moment-to-moment smile detection algorithm. Secondly, we formulate a binary classification problem (zapping/non-zapping) based on real-world scenarios, and adopt smile response as the feature to predict zapping. Thirdly, to cope with the lack of a metric in advertising evaluation, we propose a new metric called Zapping Index (ZI). ZI is a moment-to-moment measurement of a user's zapping probability. It gauges not only the reaction of a user, but also the preference of a user to commercials. Finally, extensive experiments are performed to provide insights and we make recommendations that will be useful to both advertisers and advertisement publishers
Cost-effectiveness of counselling, graded-exercise and usual care for chronic fatigue: evidence from a randomised trial in primary care
Fatigue is common and has been shown to result in high economic costs to society. The aim of this study is to compare the cost-effectiveness of two active therapies, graded-exercise (GET) and counselling (COUN) with usual care plus a self-help booklet (BUC) for people presenting with chronic fatigue
Empirical description of beta-delayed fission partial half-lives
Background: The process of beta-delayed fission (bDF) provides a versatile
tool to study low-energy fission in nuclei far away from the beta-stability
line, especially for nuclei which do not fission spontaneously. Purpose: The
aim of this paper is to investigate systematic trends in bDF partial
half-lives. Method: A semi-phenomenological framework was developed to
systematically account for the behavior of bDF partial half-lives. Results: The
bDF partial half-life appears to exponentially depend on the difference between
the Q value for beta decay of the parent nucleus and the fission-barrier energy
of the daughter (after beta decay) product. Such dependence was found to arise
naturally from some simple theoretical considerations. Conclusions: This
systematic trend was confirmed for experimental bDF partial half-lives spanning
over 7 orders of magnitudes when using fission barriers calculated from either
the Thomas-Fermi or the liquid-drop fission model. The same dependence was also
observed, although less pronounced, when comparing to fission barriers from the
finite-range liquid-drop model or the Thomas-Fermi plus Strutinsky Integral
method.Comment: accepted for publication in Phys. Rev.
Observation of sub-Poisson photon statistics in the cavity-QED microlaser
We have measured the second-order correlation function of the cavity-QED
microlaser output and observed a transition from photon bunching to
antibunching with increasing average number of intracavity atoms. The observed
correlation times and the transition from super- to sub-Poisson photon
statistics can be well described by gain-loss feedback or enhanced/reduced
restoring action against fluctuations in photon number in the context of a
quantum microlaser theory and a photon rate equation picture. However, the
theory predicts a degree of antibunching several times larger than that
observed, which may indicate the inadequacy of its treatment of atomic velocity
distributions.Comment: 4 pages, 4 figure
Binary pulsars as probes of a Galactic dark matter disk
As a binary pulsar moves through a wind of dark matter particles, the
resulting dynamical friction modifies the binary's orbit. We study this effect
for the double disk dark matter (DDDM) scenario, where a fraction of the dark
matter is dissipative and settles into a thin disk. For binaries within the
dark disk, this effect is enhanced due to the higher dark matter density and
lower velocity dispersion of the dark disk, and due to its co-rotation with the
baryonic disk.We estimate the effect and compare it with observations for two
different limits in the Knudsen number (). First, in the case where DDDM is
effectively collisionless within the characteristic scale of the binary
() and ignoring the possible interaction between the pair of dark
matter wakes. Second, in the fully collisional case (), where a fluid
description can be adopted and the interaction of the pair of wakes is taken
into account. We find that the change in the orbital period is of the same
order of magnitude in both limits. A comparison with observations reveals good
prospects to probe currently allowed DDDM models with timing data from binary
pulsars in the near future. We finally comment on the possibility of extending
the analysis to the intermediate (rarefied gas) case with .Comment: 15 pages, 6 figures. Few comments and references added, version
accepted for publication in Physics of the Dark Universe (PDU
Who Contributes to the Knowledge Sharing Economy?
Information sharing dynamics of social networks rely on a small set of
influencers to effectively reach a large audience. Our recent results and
observations demonstrate that the shape and identity of this elite, especially
those contributing \emph{original} content, is difficult to predict.
Information acquisition is often cited as an example of a public good. However,
this emerging and powerful theory has yet to provably offer qualitative
insights on how specialization of users into active and passive participants
occurs.
This paper bridges, for the first time, the theory of public goods and the
analysis of diffusion in social media. We introduce a non-linear model of
\emph{perishable} public goods, leveraging new observations about sharing of
media sources. The primary contribution of this work is to show that
\emph{shelf time}, which characterizes the rate at which content get renewed,
is a critical factor in audience participation. Our model proves a fundamental
\emph{dichotomy} in information diffusion: While short-lived content has simple
and predictable diffusion, long-lived content has complex specialization. This
occurs even when all information seekers are \emph{ex ante} identical and could
be a contributing factor to the difficulty of predicting social network
participation and evolution.Comment: 15 pages in ACM Conference on Online Social Networks 201
Pure spin current in a two-dimensional topological insulator
We predict a mechanism to generate a pure spin current in a two-dimensional
topological insulator. As the magnetic impurities exist on one of edges of the
two-dimensional topological insulator, a gap is opened in the corresponding
gapless edge states but another pair of gapless edge states with opposite spin
are still protected by the time-reversal symmetry. So the conductance plateaus
with the half-integer values can be obtained in the gap induced by
magnetic impurities, which means that the pure spin current can be induced in
the sample. We also find that the pure spin current is insensitive to weak
disorder. The mechanism to generate pure spin currents is generalized for
two-dimensional topological insulators.Comment: 5 pages, 6 figure
Application of complex network principles to key station identification in railway network efficiency analysis
Network efficiency analysis becomes important in railways in order to contribute towards improving the safety and capacity of the rail network, making rail travel more attractive for passengers, and improving industry practice and informing policy development. However, a physical railway network structure is a complicated system, and the operation, maintenance, and management of such a network is a difficult task which may be affected by many influential factors. By using efficiency analysis technology for a railway network, combining physical structure with operation functions can help railway industry to optimize the railway network while improving its efficiency and reliability. This paper presents a new methodology based on complex network principles that combines the physical railway structure with railway operation strategy for a railway network efficiency analysis. In this method, two network models of railway physical and train flow networks are developed for the identification of key stations in the railway network based on network efficiency contribution in which the terms of degree, strength, betweenness, clustering coefficient, and a comprehensive factor are taken into consideration. Once the key stations have been identified and analysed, the railway network efficiency is then studied on the basis of selective and random modes of the station failures. A case study is presented in this paper to demonstrate the application of the proposed methodology. The results show that the identified key stations in the railway network play an important role in improving the overall railway network efficiency, which can provide useful information to railway designers, engineers, operators and maintainers to operate and maintain railway network effectively and efficiently
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