Effect of Monetary Reward on Users' Individual Strategies Using Co-Evolutionary Learning

Consumer generated media (CGM), such as social networking services rely on the voluntary activity of users to prosper, garnering the psychological rewards of feeling connected with other people through comments and reviews received online. To attract more users, some CGM have introduced monetary rewards (MR) for posting activity and quality articles and comments. However, the impact of MR on the article posting strategies of users, especially frequency and quality, has not been fully analyzed by previous studies, because they ignored the difference in the standpoint in the CGM networks, such as how many friends/followers they have, although we think that their strategies vary with their standpoints. The purpose of this study is to investigate the impact of MR on individual users by considering the differences in dominant strategies regarding user standpoints. Using the game-theoretic model for CGM, we experimentally show that a variety of realistic dominant strategies are evolved depending on user standpoints in the CGM network, using multiple-world genetic algorithm.Comment: Accepted to 9th International Conference on Computational Social Science (IC2S2 2023) 5 figures, 3 tables, 4 page

Risk factors for severity of colonic diverticular hemorrhage

Background/AimsColonic diverticular hemorrhage (DH) was a rare disease until the 1990s, and its incidence has increased rapidly since 2000 in Japan. In recent years, colonic DH has been the most frequent cause of lower gastrointestinal bleeding (LGIB). Nearly all cases of DH are mild, with the bleeding often stopping spontaneously. Some cases, however, require surgery or arterial embolization. In this study, using a cohort at Fukuoka University Chikushi Hospital, we investigated factors associated with severe colonic DH.MethodsAmong patients with LGIB who underwent colonoscopy at our hospital between 1995 and 2013, DH was identified in 273 patients. Among them, 62 patients (22.7%) were defined as having severe colonic DH according to recurrence of bleeding in a short period, and/or the necessity of transfusion, arterial embolization, or surgery. We then evaluated risk factors for severe DH among DH patients in this retrospective cohort.ResultsAmong the 273 patients with DH, use of non-steroidal anti-inflammatory drugs (NSAIDs) (odds ratio [OR], 2.801; 95% confidence interval [CI], 1.164–6.742), Charlson Risk Index (CRI) ≥2 (OR, 3.336; 95% CI, 1.154–7.353), right-sided colonic DH (OR, 3.873; 95% CI, 1.554–9.653), and symptoms of cerebral hypoperfusion (such as light-headedness, dizziness, or syncope) (OR, 2.926; 95% CI, 1.310–6.535) showed an increased risk of severe DH even after controlling for other factors.ConclusionsSevere DH occurred in 23% of DH patients, and NSAID use, CRI ≥2, right-sided colonic DH, and symptoms of cerebral hypoperfusion are suggested to be predictors of severe DH

Nature of a white opaque substance visualized by magnifying endoscopy in colorectal hyperplastic polyps*

Background and study aims A white opaque substance (WOS) has been observed in the epithelia of gastric, duodenal, and colorectal epithelial adenomas and carcinomas, using magnifying endoscopy (ME). The WOS has been reported to be derived from a dense accumulation of minute lipid droplets in the epithelium. This study aimed to investigate whether the WOS in colorectal hyperplastic polyps was derived from lipid droplets accumulated in the epithelium, as observed in the case of gastric, duodenal, and colorectal epithelial neoplasms. Patients and methods We analyzed 30 consecutive patients who were positive for the WOS, as visualized in colorectal hyperplastic polyps by ME with narrow-band imaging and 30 consecutive patients who were negative for the WOS. Biopsy specimens obtained from the polyps were immunostained with anti-adipophilin antibody to determine the correlation between the presence of the WOS and that of lipid droplets in the epithelium. Results In all patients, the epithelial cells were histologically positive for adipophilin. However, the area of adipophilin-positive epithelial cells in the WOS-positive group was significantly larger than that in the WOS-negative group (P < 0.001). The density of the WOS was strongly and positively correlated with the area of adipophilin-positive cells. Conclusions This study reveals that the WOS visualized in the superficial layers of colorectal hyperplastic polyps is produced by a dense accumulation of minute lipid droplets in the epithelia of the polyps