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Hsu et al. Neuroimmunol Neuroinflammation 2018;5:9 I http://dx.doi.org/10.20517/2347-8659.2018.03 Page 3 of 9

eminent journals and authors in neuroimmunology and neuroinflammation; (3) the recent research domains
defined by authors; and (4) the cluster coefficients (CCs) in different networks.

METHODS
Data sources
We programed Microsoft Excel VBA modules to extract abstracts and their corresponding co-author names
as well as author-defined keywords for each article on January 22, 2018, from Medline since 1982. Only
those abstracts published by the keyword (neuroimmunology [Title] OR neuroinflammation [Title]) were
included. Others like those labeled with Published Erratum, Editorial or without author nation name were
excluded from this study. A total of 2885 eligible abstracts were obtained from the Medline.

Data arrangement to fit SNA requirement
Before visualizing our results using SNA, we organized data in compliance with the format and guidelines
defined by Pajek software . Microsoft Excel VBA was used to deal with data fitting to the SNA requirement.
[15]

Graphical representations to report
Author nations and their relations
Two tables (i.e. columns for publication years and rows for the 1st author nations or journals) were
made for presenting the distribution in nation (of journal) for the domain of neuroimmunology and
neuroinflammation. The bigger bubble means, the more number of the nodes (i.e. nations, or keywords
in this study). The wider line indicates, the stronger relations between the 2 nodes. Community clusters
are filled with different colors in bubbles. The most eminent authors were calculated from the Medline
library since 1982.

Keywords to present the research domain
If keywords represent the research domain, the stronger relations between the two keywords can be
highlighted and linked by SNA. Like the concept of co-occurrence about beer and diaper sales during
weekend. The presentation for the bubble and line is similar to the previous section in the interpretation.
Keywords defined by the authors were applied to represent the domains in the current study.

Statistical tools and data analyses
[15]
[16]
Google Maps and SNA Pajek software were used to display and visualized representations for eminent
authors and keywords in relation with neuroimmunology and neuroinflammation. Author-made Excel VBA
modules were applied to organize the data. CC represents the density of a network and a significant level
(> 1.96) is defined by t-value as the formula [= CC × [(n-1)/(1-CC )] ], where n = the number of nodes in a
2 1/2
network.

In contrast, E-I index is defined by the formula, where EL = the number of external friendship links and IL
= the number of internal friendship links . The negative E-I index means a coherence cluster in existence.
[17]
Similarly, the higher CC indicates many members are members’ friends linked to others. Density denotes as
the ratio of the linkage members over all possible members.

RESULTS
Author nations and their relations
A total of 2799 eligible papers with complete author nations based on journal article since 1982 are in Table 1. We
can see that the most number of articles are from the countries of USA (902, 32.23%) and China (363, 12.97%). The