34,698 research outputs found
Assessing Percolation Threshold Based on High-Order Non-Backtracking Matrices
Percolation threshold of a network is the critical value such that when nodes
or edges are randomly selected with probability below the value, the network is
fragmented but when the probability is above the value, a giant component
connecting large portion of the network would emerge. Assessing the percolation
threshold of networks has wide applications in network reliability, information
spread, epidemic control, etc. The theoretical approach so far to assess the
percolation threshold is mainly based on spectral radius of adjacency matrix or
non-backtracking matrix, which is limited to dense graphs or locally treelike
graphs, and is less effective for sparse networks with non-negligible amount of
triangles and loops. In this paper, we study high-order non-backtracking
matrices and their application to assessing percolation threshold. We first
define high-order non-backtracking matrices and study the properties of their
spectral radii. Then we focus on 2nd-order non-backtracking matrix and
demonstrate analytically that the reciprocal of its spectral radius gives a
tighter lower bound than those of adjacency and standard non-backtracking
matrices. We further build a smaller size matrix with the same largest
eigenvalue as the 2nd-order non-backtracking matrix to improve computation
efficiency. Finally, we use both synthetic networks and 42 real networks to
illustrate that the use of 2nd-order non-backtracking matrix does give better
lower bound for assessing percolation threshold than adjacency and standard
non-backtracking matrices.Comment: to appear in proceedings of the 26th International World Wide Web
Conference(WWW2017
Variable selection based on entropic criterion and its application to the debris-flow triggering
We propose a new data analyzing scheme, the method of minimum entropy
analysis (MEA), in this paper. New MEA provides a quantitative criterion to
select relevant variables for modeling the physical system interested. Such
method can be easily extended to various geophysical/geological data analysis,
where many relevant or irrelevant available measurements may obscure the
understanding of the highly complicated physical system like the triggering of
debris-flows. After demonstrating and testing the MEA method, we apply this
method to a dataset of debris-flow occurrences in Taiwan and successfully find
out three relevant variables, i.e. the hydrological form factor, numbers and
areas of landslides, to the triggering of observed debris-flow events due to
the 1996 Typhoon Herb.Comment: 9 pages and 4 table
Effects of Ox-LDL on Macrophages NAD(P)H Autofluorescence Changes by Two-photon Microscopy
Ox-LDL uptakes by macrophage play a critical role in the happening of
atherosclerosis. Because of its low damage on observed cells and better
signal-to- background ratio, two-photon excitation fluorescence microscopy is
used to observe NAD(P)H autofluorescence of macrophage under difference
cultured conditions- bare cover glass, coated with fibronectin or
poly-D-lysine. The results show that the optimal condition is fibronectin
coated surface, on which, macrophages profile can be clearly identified on
NAD(P)H autofluorescence images collected by two-photon microscopy. Moreover,
different morphology and intensities of autofluorescence under different
conditions were observed as well. In the future, effects of ox-LDL on
macrophages will be investigated by purposed system to research etiology of
atherosclerosis.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
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