2,445 research outputs found
PEER REVIEWER RECOMMENDATION IN ONLINE SOCIAL LEARNING CONTEXT: INTEGRATING INFORMATION OF LEARNERS AND SUBMISSIONS
With the rapid development of massive open online courses, peer assessment has played an important role in promoting social learning. According to social learning theory, peer assessment in online courses provides students a chance to learn from each other when they review other students’ submissions, which motivates their participation in online social learning. However, existing peer assessment cannot generate satisfactory results in that a systematic approach to find peer reviewers for submissions is lacked. To address this problem, this paper proposes a reviewer recommendation system which can suggest appropriate reviewers for submissions during the process of peer assessment. This recommendation system is built by integrating information of learners and submissions. The integration of this reviewer recommendation system in the process of peer assessment may help to improve learners’ satisfaction and their learning performance. Additionally, the reviewer recommendation system can also be used in many other fields such as enterprise training or language learning online
Revisiting B_s\to\mu^+\mu^- and B\to K^{(*)}\mu^+\mu^- decays in the MSSM with and without R-parity
The rare decays B_s -> \mu^+\mu^- and B -> K^{(*)}\mu^+\mu^- are sensitive to
new particles and couplings via their interferences with the standard model
contributions. Recently, the upper bound on B(B_s -> \mu^+\mu^-) has been
improved significantly by the CMS, LHCb, CDF, and D{\O} experiments. Combining
with the measurements of B(B-> K^{(*)}\mu^+\mu^-), we derive constraints on the
relevant parameters of minimal supersymmetic standard model with and without
R-parity, and examine their contributions to the dimuon forward-backward
asymmetry in B-> K^{*}\mu^+\mu^- decay. We find that (i) the contribution of
R-parity violating coupling products
\lambda^{\prime}_{2i2}\lambda^{\prime*}_{2i3} due to squark exchange is
comparable with the theoretical uncertainties in B-> K \mu^+\mu^- decay, but
still could be significant in B-> K^{*}\mu^+\mu^- decay and could account for
the forward-backward asymmetry in all dimuon invariant mass regions; (ii) the
constrained mass insertion (\delta^{u}_{LL})_{23} could have significant
contribution to dA_{FB}(B-> K^{*}\mu^+\mu^-)/ds, and such effects are favored
by thr recent results of the Belle, CDF, and LHCb experiments.Comment: 20 pages, 9 figures, published versio
Characterization and properties of weakly optimal entanglement witnesses
We present an analysis of the properties and characteristics of weakly
optimal entanglement witnesses, that is witnesses whose expectation value
vanishes on at least one product vector. Any weakly optimal entanglement
witness can be written as the form of ,
where is a non-negative number and is the identity
matrix. We show the relation between the weakly optimal witness and
the eigenvalues of the separable states . Further we give an
application of weakly optimal witnesses for constructing entanglement witnesses
in a larger Hilbert space by extending the result of [P. Badzi\c{a}g {\it et
al}, Phys. Rev. A {\bf 88}, 010301(R) (2013)], and we examine their geometric
properties.Comment: 13 pages, 2 figures, has been extensively redrafted and restructure
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