9,451 research outputs found
Attributed Network Embedding for Learning in a Dynamic Environment
Network embedding leverages the node proximity manifested to learn a
low-dimensional node vector representation for each node in the network. The
learned embeddings could advance various learning tasks such as node
classification, network clustering, and link prediction. Most, if not all, of
the existing works, are overwhelmingly performed in the context of plain and
static networks. Nonetheless, in reality, network structure often evolves over
time with addition/deletion of links and nodes. Also, a vast majority of
real-world networks are associated with a rich set of node attributes, and
their attribute values are also naturally changing, with the emerging of new
content patterns and the fading of old content patterns. These changing
characteristics motivate us to seek an effective embedding representation to
capture network and attribute evolving patterns, which is of fundamental
importance for learning in a dynamic environment. To our best knowledge, we are
the first to tackle this problem with the following two challenges: (1) the
inherently correlated network and node attributes could be noisy and
incomplete, it necessitates a robust consensus representation to capture their
individual properties and correlations; (2) the embedding learning needs to be
performed in an online fashion to adapt to the changes accordingly. In this
paper, we tackle this problem by proposing a novel dynamic attributed network
embedding framework - DANE. In particular, DANE first provides an offline
method for a consensus embedding and then leverages matrix perturbation theory
to maintain the freshness of the end embedding results in an online manner. We
perform extensive experiments on both synthetic and real attributed networks to
corroborate the effectiveness and efficiency of the proposed framework.Comment: 10 page
3-Chloro-N′-[(2-methoxynaphthalen-1-yl)methylidene]benzohydrazide
The title compound, C19H15ClN2O2, was prepared by the reaction of 2-methoxy-1-naphthaldehyde with 3-chlorobenzohydrazide in methanol. The dihedral angle between the benzene ring and the naphthyl ring system is 69.0 (3)°. In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into chains along the c axis. The crystal packing exhibits π–π interactions, as indicated by distances of 3.768 (3) Å between the centroids of the naphthyl rings of neighbouring molecules
Cold Dark Matter Isocurvature Perturbations: Cosmological Constraints and Applications
In this paper we present the constraints on cold dark matter (CDM)
isocurvature contributions to the cosmological perturbations. By employing
Markov Chain Monte Carlo method (MCMC), we perform a global analysis for
cosmological parameters using the latest astronomical data, such as 7-year
Wilkinson Microwave Anisotropy Probe (WMAP7) observations, matter power
spectrum from the Sloan Digital Sky Survey (SDSS) luminous red galaxies (LRG),
and "Union2" type Ia Supernovae (SNIa) sample. We find that the correlated
mixture of adiabatic and isocurvature modes are mildly better fitting to the
current data than the pure adiabatic ones, with the minimal given by
the likelihood analysis being reduced by 3.5. We also obtain a tight limit on
the fraction of the CDM isocurvature contributions, which should be less than
14.6% at 95% confidence level. With the presence of the isocurvature modes, the
adiabatic spectral index becomes slightly bigger, n_s^{\rm
adi}=0.972\pm0.014~(1\,\sigma), and the tilt for isocurvature spectrum could be
large, namely, the best fit value is n_s^{\rm iso}=3.020. Finally, we discuss
the effect on WMAP normalization priors, shift parameter R, acoustic scale l_A
and z_{*}, from the CDM isocurvaure perturbation. By fitting the mixed initial
condition to the combined data, we find the mean values of R, l_A and z_{*} can
be changed about 2.9\sigma, 2.8\sigma and 1.5\sigma respectively, comparing
with those obtained in the pure adiabatic condition.Comment: 9 pages, 5 figures, 3 tables, references adde
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