Non-independent Cascade Formation

Author(s):  
Biru Cui ◽  
Shanchieh Jay Yang ◽  
Christopher Homan
Keyword(s):  
2022 ◽  
Vol 16 (1) ◽  
pp. 1-24
Author(s):  
Marinos Poiitis ◽  
Athena Vakali ◽  
Nicolas Kourtellis

Aggression in online social networks has been studied mostly from the perspective of machine learning, which detects such behavior in a static context. However, the way aggression diffuses in the network has received little attention as it embeds modeling challenges. In fact, modeling how aggression propagates from one user to another is an important research topic, since it can enable effective aggression monitoring, especially in media platforms, which up to now apply simplistic user blocking techniques. In this article, we address aggression propagation modeling and minimization in Twitter, since it is a popular microblogging platform at which aggression had several onsets. We propose various methods building on two well-known diffusion models, Independent Cascade ( IC ) and Linear Threshold ( LT ), to study the aggression evolution in the social network. We experimentally investigate how well each method can model aggression propagation using real Twitter data, while varying parameters, such as seed users selection, graph edge weighting, users’ activation timing, and so on. It is found that the best performing strategies are the ones to select seed users with a degree-based approach, weigh user edges based on their social circles’ overlaps, and activate users according to their aggression levels. We further employ the best performing models to predict which ordinary real users could become aggressive (and vice versa) in the future, and achieve up to AUC = 0.89 in this prediction task. Finally, we investigate aggression minimization by launching competitive cascades to “inform” and “heal” aggressors. We show that IC and LT models can be used in aggression minimization, providing less intrusive alternatives to the blocking techniques currently employed by Twitter.


2006 ◽  
Vol 105 (2) ◽  
pp. 288-293 ◽  
Author(s):  
Yoshifumi Kawanabe ◽  
Tomoh Masaki ◽  
Nobuo Hashimoto

Object Endothelin 1 (ET-1) is a major cause of cerebral vasospasm after subarachnoid hemorrhage (SAH), and extracellular Ca++ influx plays an essential role in ET-1–induced vasospasm. The authors recently demonstrated that ET-1 activates two types of Ca++-permeable nonselective cation channels (designated NSCC-1 and NSCC-2) and a store-operated Ca++ channel (SOCC) in vascular smooth-muscle cells located in the basilar arteries (BAs) of rabbits. In the present study, they investigate the effects of phospholipase C (PLC) on ET-1–induced activation of these Ca++ channels and BA contraction by using the PLC inhibitor U73122. Methods To determine which Ca++ channels are activated via a PLC-dependent pathway, these investigators monitored the intracellular free Ca++ concentration ([Ca++]i). The role of PLC in ET-1–induced vascular contraction was examined by performing a tension study of rabbit BA rings. The U73122 inhibited the ET-1–induced transient increase in [Ca++]i, which resulted from mobilization of Ca++; from the intracellular store. Phospholipase C also inhibited ET-1–induced extracellular Ca++ influx through the SOCC and NSCC-2, but not through the NSCC-1. The U73122 inhibited the ET-1–induced contraction of the rabbit BA rings, which depended on extracellular Ca++ influx through the SOCC and NSCC-2. Conclusions These results indicate the following. 1) The SOCC and NSCC-2 are stimulated by ET-1 via a PLC-dependent cascade whereas NSCC-1 is stimulated via a PLC-independent cascade. 2) The PLC is involved in the ET-1–induced contraction of rabbit BA rings, which depends on extracellular Ca++ influx through the SOCC and NSCC-2.


2018 ◽  
Vol 50 (2) ◽  
pp. 480-503
Author(s):  
Rémi Lemonnier ◽  
Kevin Scaman ◽  
Nicolas Vayatis

Abstract In this paper we derive nonasymptotic upper bounds for the size of reachable sets in random graphs. These bounds are subject to a phase transition phenomenon triggered by the spectral radius of the hazard matrix, a reweighted version of the adjacency matrix. Such bounds are valid for a large class of random graphs, called local positive correlation (LPC) random graphs, displaying local positive correlation. In particular, in our main result we state that the size of reachable sets in the subcritical regime for LPC random graphs is at most of order O(√n), where n is the size of the network, and of order O(n2/3) in the critical regime, where the epidemic thresholds are driven by the size of the spectral radius of the hazard matrix with respect to 1. As a corollary, we also show that such bounds hold for the size of the giant component in inhomogeneous percolation, the SIR model in epidemiology, as well as for the long-term influence of a node in the independent cascade model.


Sign in / Sign up

Export Citation Format

Share Document