Suchergebnisse

Abstract
Background
Total dissolved gas (TDG) caused by the rapid outflow of water from dams may threaten the survival of fish. However, few studies have assessed the impact of fish size on their tolerance to TDG supersaturation in the Yangtze River. To investigate the influences of fish size on the TDG supersaturation tolerance of fish, juvenile grass carp (Ctenopharyngodon idellus) of two sizes were subjected to TDG-supersaturated water at high levels (125%, 130%, 135% and 140%). Furthermore, varying flood flows may cause different TDG levels during the flood season. Fish may be subjected to low, chronic exposure to TDG before peak flooding occurs. However, TDG tolerance in fish subjected to high levels of TDG-supersaturated water after chronic exposure is rare. To further investigate the tolerance of juvenile grass carp subjected to acute exposure after chronic TDG exposure, juvenile grass carp were exposed to high levels of TDG-supersaturated water (125–140%) after receiving 96 h of chronic exposure (115% TDG).

Results
In the single acute exposure and multiple exposures (acute exposure after chronic exposure), similar abnormal behaviours and symptoms of gas bubble disease (GBD) were observed in the juvenile grass carp subjected to the TDG-supersaturated water. No abnormal behaviour or mortality was observed in fish in the first chronic exposure of the multiple-exposure treatment. As the TDG level increased, the mortality of the large and small juvenile grass carp increased. The median lethal time (LT50) for the large juvenile grass carp was 36.55, 21.75 and 6.37 h at 130%, 135% and 140% TDG levels, respectively, while the LT50 value of the small juvenile grass carp was 88.13, 61.49 and 35.88 h at the same TDG levels, respectively. In addition, the LT50 value of juvenile grass carp during acute TDG exposure after chronic exposure was 26.22, 7.54 and 5.34 h at 130%, 135% and 140% TDG levels, respectively.

Conclusion
The tolerance of juvenile grass carp decreased with increasing TDG levels. The large juvenile grass carp had weaker tolerance to TDG-supersaturated water than the small juvenile grass carp. In addition, compared with juvenile grass carp subjected to single acute exposure, juvenile grass carp subjected to multiple exposures exhibited lower tolerance and were more vulnerable to the adverse effects of TDG.

AbstractRecent years have seen a global surge in affective polarization, extending from the US to European and Asian democracies. Concurrently, empirical research proliferates, exploring factors driving this rise, with significant focus on aspects like partisan strength and in-party affective attitude. This scoping review sheds light on investigated predictors of partisan strength and in-party affect and associated mechanisms of influence on the two key outcomes to better our understanding of affective polarization and the current research in the field. Employing a standardized search protocol across nine databases, we reviewed 26,148 reports, yielding 32 eligible reports with 50 studies and 56 predictors. Using common themes and theories between predictors as anchors for categorization, we found that: 1) providing platform information or engaging in active political discussion strengthens partisan strength, particularly when information allows clear comparison between parties; 2) selective recall and interpretation bolster in-party affect and partisan strength, with the information's susceptibility to manipulation moderating the effect of selective interpretation or on in-party affect; 3) subjective and objective sorting strengthens the two key outcomes, but objective membership in social group is critical for effect of sorting on partisan strength, and that identity moderate each other's impact of elicited cross-pressure; 4) party identity salience and the context thereof boosts partisan strength; 5) the effect of need for closure and authoritarianism on partisan strength likely depends on voter demographics, however, the NFA and authoritarianism positively correlates to in-party affect across demographics; 6) factors enhancing group-centric thinking intensify the two key outcomes, and factors enhancing issue-based thinking (e.g., having independent parents) reduces them; 7) ideological and issue misalignment diminishes the two outcomes; 8) the structure of partisan attitude varies across partisan strength, with contrasting evidence on whether leaners are influenced primarily by instrumental or a combination of affective and instrumental attitudes towards in-party; 9) interventions aimed at enhancing interparty cohesion have limited impact on the two outcomes; 10) stronger partisans are also more consistent and loyal voters. We also identified significant limitations and opportunities in the existing research methodology. We encourage future studies to justify the use of specific operationalizations as there is now an expanding list of operationalization driven by distinct underlying theories. Studies should also perform preliminary validation of mechanisms other than theoretical explanations. Overall, our review provided a preliminary categorization of predictors to articulate empirical gaps in the literature, establish narratives to enhance systematic growth of the topic, and provide insight to drive successful interventions for reducing polarization.