2,164 research outputs found
The effect of heterogeneous dynamics of online users on information filtering
The rapid expansion of the Internet requires effective information filtering techniques to extract the most essential and relevant information for online users. Many recommendation algorithms have been proposed to predict the future items that a given user might be interested in. However, there is an important issue that has always been ignored so far in related works, namely the heterogeneous dynamics of online users. The interest of active users changes more often than that of less active users, which asks for different update frequency of their recommendation lists. In this paper, we develop a framework to study the effect of heterogeneous dynamics of users on the recommendation performance. We find that the personalized application of recommendation algorithms results in remarkable improvement in the recommendation accuracy and diversity. Our findings may help online retailers make better use of the existing recommendation methods
Non-Markovian effect on the quantum discord
We study the non-Markovian effect on the dynamics of the quantum discord by
exactly solving a model consisting of two independent qubits subject to two
zero-temperature non-Markovian reservoirs, respectively. Considering the two
qubits initially prepared in Bell-like or extended Werner-like states, we show
that there is no occurrence of the sudden death, but only instantaneous
disappearance of the quantum discord at some time points, in comparison to the
entanglement sudden death in the same range of the parameters of interest. It
implies that the quantum discord is more useful than the entanglement to
describe quantum correlation involved in quantum systems.Comment: 5 pages, 5 figure
Fragmentation function of in soft gluon factorization and threshold resummation
We study the fragmentation function of the gluon to color-octet heavy
quark-antiquark pair using the soft gluon factorization (SGF) approach, which
expresses the fragmentation function in a form of perturbative short-distance
hard part convoluted with one-dimensional color-octet soft gluon
distribution (SGD). The short distance hard part is calculated to
next-to-leading order in and a renormalization group equation for
the SGD is derived. By solving the renormalization group equation, threshold
logarithms are resummed to all orders in perturbation theory. The comparison
with gluon fragmentation function calculated in NRQCD factorization approach
indicates that the SGF formula resums a series of velocity corrections in NRQCD
which are important for phenomenological study.Comment: 38 pages, 8 figure
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