Biofilm formation is likely to contribute greatly to antibiotic resistance in bacteria and therefore the efficient removal of bacterial biofilms needs addressing urgently. Here, we reported that the supplement of non-inhibitory concentration of N-acetyl-L-cysteine (NAC), a common reactive oxygen species (ROS) scavenger, can significantly reduce the biomass of mature Pseudomonas aeruginosa biofilms (corroborated by crystal violet assay and laser scanning confocal microscopy). 1 mM NAC increased the cheater (ΔlasR mutant) frequency to 89.4 ± 1.5% in the evolved PAO1 after the 15-day treatment. Scavenging of ROS by NAC induced the collapse of P. aeruginosa biofilms, but it did not alter quorum sensing-regulated genes expression (e.g., hcnC and cioAB) and hydrogen cyanide production. The replenishment of public good protease contributed to the recovery of biofilm biomass, indicating the role of disrupting policing in biofilm inhibition. Furthermore, 7 typical ROS scavengers (e.g., superoxide dismutase, catalase and peroxidase, etc.) also effectively inhibited mature P. aeruginosa biofilms. This study demonstrates that scavenging of ROS can promote the selective control of P. aeruginosa biofilms through policing disruption as a targeted biofilm control strategy in complex water environments.

How do authoritarian states organize their coercive institutions over space? We argue that autocrats maximize the utility of their limited coercive resources by clustering them with perceived threats in society, i.e., segments of the population that are ideologically distant and have mobilizational potential. We test this proposition using a dataset that covers the universe of police stations (N = 147,428) and religious sites (N = 115,394) in China. We find that police stations are more likely to be located within walking distance of foreign religious sites (churches) than other sites (temples), even after controlling for the estimated population within 1 km of each site and a set of key site attributes. This finding is robust to using alternative model specifications, different variable measurements, and multiple data sources. Moving beyond the clustering pattern, we also address the temporal order issue and show that the Chinese state has allocated more new coercive resources around existing foreign religious sites than native sites, i.e., after these sites are already in place. This study enriches our understanding of how autocrats rule and further opens up an emerging new methodological avenue for research on authoritarian politics.

BACKGROUND: Injury prevention is an important issue for police officers, but the effectiveness of prevention initiatives is dependent on officers\' motivation toward, and adherence to, recommended health and safety guidelines.
OBJECTIVE: To understand effects of police officers\' motivation to prevent occupational injury on beliefs about safety and adherence to injury prevention behaviours.
METHODS: Full-time police officers completed a survey comprising validated psychometric scales to assess autonomous, controlled and amotivated forms of motivation (Treatment Self-Regulation Questionnaire), behavioural adherence (Self-reported Treatment Adherence Scale) and beliefs (Safety Attitude Questionnaire) with respect to injury prevention behaviours.
RESULTS: There were 207 participants; response rate was 87%. Hierarchical multiple regression analyses demonstrated that autonomous motivation was positively related to behavioural adherence, commitment to safety and prioritizing injury prevention. Controlled motivation was a positive predictor of safety communication barriers. Amotivation was positively associated with fatalism regarding injury prevention, safety violation and worry.
CONCLUSIONS: These findings are consistent with the tenets of self-determination theory in that autonomous motivation was a positive predictor of adaptive safety beliefs and adherence to injury prevention behaviours.