Pairwise stable and stochastically stable networks in the four-person co-author model

The co-author model is introduced by Jackson and Wolinsky (1996, Journal of Economic Theory) as a typical example of the models of network formation. In this note, we study which network is pairwise stable and/or stochastically stable when the number of players is four.

Lifespan of information service firms in Japan: a survival analysis

The purpose of this paper is an analysis of survival in the Japanese information service industry. Information service firms are generally classified into two typical patterns. One is the group of independent firms such as software vendors, and the other is the group of non-independent such as subsidiaries established by spinning off and so on. We used a sample of 334 firms in Japan and analyzed by Kaplan-Meier estimator method and Cox proportional hazard regression model in order to investigate the difference of survival between these two groups and/or among other attributes. As a result, the lifespan of the information service firms significantly depends on the degree of system integration sales ratio, software development sales ratio, and entrusted processing sales ratio. On the contrary, property of non-independence and high sales ratio with main customers have a negative influence on their survival rates, i.e. lifespan. The paper discusses these results and offers some managerial implications, and future research opportunities are provided

Lifespan of information service firms in Japan: a survival analysis

The purpose of this paper is an analysis of survival in the Japanese information service industry. Information service firms are generally classified into two typical patterns. One is the group of independent firms such as software vendors, and the other is the group of non-independent such as subsidiaries established by spinning off and so on. We used a sample of 334 firms in Japan and analyzed by Kaplan-Meier estimator method and Cox proportional hazard regression model in order to investigate the difference of survival between these two groups and/or among other attributes. As a result, the lifespan of the information service firms significantly depends on the degree of system integration sales ratio, software development sales ratio, and entrusted processing sales ratio. On the contrary, property of non-independence and high sales ratio with main customers have a negative influence on their survival rates, i.e. lifespan. The paper discusses these results and offers some managerial implications, and future research opportunities are provided

Preliminary Study on a System for Visualization of Big Data in SMEs

The 2012 White Paper on Information and Communications in Japan issued by the Ministry of Internal Affairs and Communications of Japan advocates use of big data under its “Special Theme: ICT-induced and accelerated Disaster Recovery and Japan’s Re-birth.” However, the analysis in the Japan Users Association of Information Systems’ white paper on its 2014 IT trend survey for companies reports that less than 10% of companies utilize big data, and it would appear that progress in its use is centered on large firms. Under such conditions, use of big data is becoming a challenge for the purpose of ensuring the survival and success of SMEs as well. As a result, R&D and technological support for SMEs are becoming pressing issues. However, at present there has been almost no academic research concerning policies and future directions for use of big data at SMEs. Accordingly, this study conducted the modelization of the procedure for visualization of big data for SMEs. Specifically, we organized the procedure as a tutorial, from obtaining data of Japanese hot-spring areas using web scraping, to visualizing them using the visualization software Cytoscape

BRCA1/2 Mutation Frequency is HIGH in Japanese Triple-Negative Breast Cancer Patients

Germline mutations of BRCA1/2 genes cause hereditary breast and/or ovarian cancer. However, whether guidelines like those of the National Comprehensive Cancer Network (NCCN) can suitably predict the likelihood of BRCA1/2 mutations in the Japanese population is unclear. Methods BRCA1/2 gene mutation frequencies were investigated in relation to parameters such as age, family history (FH), and breast cancer subtype using data collected from 922 Japanese breast cancer patients who underwent surgery between September 2010 and June 2013. BRCA1/2 mutations were present in 15 of 57 (26.3%) tested patients. The frequency of the mutations was not significantly related to age. Among the 180 patients who reported an FH of breast cancer, 11 of the 37 who were tested (29.7%) were positive for BRCA1/2 mutations. Of those with an FH of ovarian cancer (n = 34), seven of 12 patients tested (58.3%) were carriers of BRCA1/2 (P = 0.013). Six of these seven carriers were triple-negative breast cancer (TNBC) patients. In all, there were 97 TNBC patients, and the presence of the BRCA1/2 mutation in this subgroup was significantly greater than in non-TNBC patients, with 12 of 17 TNBC patients (70.5%) testing positive (P = 0.03). There were 59 TNBC patients < 60 years of age, and of the 16 (27.1%) who underwent BRCA1/2 genetic testing, 11 (68.8%) were found to have mutations in BRCA1/2. Among the TNBC patients, 29 also reported an FH of breast or ovarian cancer; of these, nine of the 13 tested (69.2%) were positive for a BRCA1/2 mutation. The data demonstrate that BRCA1/2 mutations are observed more frequently in TNBC patients, especially those < 60 years of age or in combination with an FH of breast and/or ovarian cancer, suggesting that some of the NCCN guidelines can adequately predict BRCA1/2 carriers in the Japanese population