Consensus, Cohesion and Connectivity

Social life clusters into groups held together by ties that also transmit information. When collective problems occur, group members use their ties to discuss what to do and to establish an agreement, to be reached quick enough to prevent discounting the value of the group decision. The speed at which a group reaches consensus can be predicted by the algebraic connectivity of the network, which also imposes a lower bound on the group's cohesion. This specific measure of connectivity is put to the test by re-using experimental data, which confirm the prediction

Knowledge Specialization, Knowledge Brokerage and the Uneven Growth of Technology Domains

Why do certain domains of knowledge grow fast while others grow slowly or stagnate? Two distinct theoretical arguments hold that knowledge growth is enhanced by knowledge specialization and knowledge brokerage. Based on the notion of recombinant knowledge growth, we show that specialization and brokerage are opposing modes of knowledge generation, the difference between them lying in the extent to which homogeneous vs. heterogeneous input ideas get creatively recombined. Accordingly, we investigate how both modes of knowledge generation can enhance the growth of technology domains. To address this question, we develop an argument that reconciles both specialization and brokerage into a dynamic explanation. Our contention is that specializing in an increasingly homogeneous set of input ideas is both more efficient and less risky than brokering knowledge. Nevertheless, specializing implies progressively exhausting available recombinant possibilities, while brokerage creates new ones. Hence, technology domains tend to grow faster when they specialize, but the more specialized they become, the more they need knowledge brokerage to grow. We cast out our argument into five hypotheses that predict how growth rates vary across technology domain

Spontaneous cooperation for public goods

Cooperation for public goods poses a dilemma, where individuals are tempted to free ride on others' contributions. Classic solutions involve monitoring, reputation maintenance and costly incentives, but there are important collective actions based on simple and cheap cues only, for example unplanned protests and revolts. This can be explained by an Ising model with the assumption that individuals in uncertain situations tend to conform to the local majority in their network. Among initial defectors, noise such as rumors or opponents' provocations causes some of them to cooperate accidentally. At a critical level of noise, these cooperators trigger a cascade of cooperation. We find an analytic relationship between the phase transition and the asymmetry of the Ising model, which in turn reflects the asymmetry of cooperation and defection. This study thereby shows that in principle, the dilemma of cooperation can be solved by nothing more than a portion of random noise, without rational decision making

Bursts of cooperation triggered by threats in violent and other uncertain situations

During intergroup confrontations, agitating stimuli such as opponents' threats and provocations can trigger collective violence, even without the usual mechanisms of cooperation such as norms with sanctions. We examine video recordings of street fights between groups of young men. Collective violence in these attacks sometimes breaks out in a burst and at other times in a fizzle wherein only few group members participate. An adapted Ising spinglass model demonstrates that these two different outcomes can be predicted by a critical level of defectors, which is strongly supported by our data

Potential dietary feed additives with antibacterial effects and their impact on performance of weaned piglets : a meta-analysis

This meta-analysis evaluated the use of potential dietary feed additives (pDFA) with antibacterial effects and their impact on the perfomance of weaned piglets. Twenty-three peer-reviewed in vivo studies, comprising 50 trials, were identified between January 2010 and January 2017. The pDFA in these studies could be grouped in 5 classes: antimicrobial peptides, chitosan, lysozyme, medium chain fatty acids/triglycerides and plant extracts. Mixed-effect meta-analyses with type of pDFA as fixed effect were performed for the growth parameters 'average daily gain' (ADG) and 'feed conversion ratio' (FCR), which are the two most important and used economic performance parameters for farmers. For each class of pDFA, results of the meta-analysis showed significantly higher average daily gain in the group with pDFA compared to the negative control group, while no significant difference with the positive control group was observed. Furthermore, a positive effect on FCR was found, i.e. significantly less feed was needed to gain 1 kg of body weight in the group with pDFA compared to the negative control group. No significant differences with positive control groups were observed for each class of pDFA, except for plant extracts, where the FCR was also significantly reduced in the treatment group. These results suggest that pDFA could reduce the use of antimicrobials without significant negative effects on performance indicators