Fact-checking has been granted a pivotal role in mitigating the effects of online disinformation, but its effectiveness has nonetheless been questioned (Lee and Shin Citation2019). Like any persuasive communication, fact checkers depend on their recipients perceiving both their messages and them as credible (Lombardi, Seyranian, and Sinatra Citation2014; Lombardi, Nussbaum, and Sinatra Citation2016). This study investigates the role of the perceived credibility of the fact checker as possible detriment to the effectiveness of fact-checking efforts by means of an online survey-embedded experiment. Results show that the perceived credibility of the fact checker and fact-checking messages is best explained by normative expectations of the roles of fact checkers and trust in traditional media. Some users perceive fact checkers as elite power structures in journalism or, in other words, as collaborative-facilitators for state propaganda (Hanitzsch and Vos Citation2018; see also Fawzi Citation2020). Further, low trust in media and politics predicts perceived credibility of disinformation better than political partisanship. The findings suggest that fact checkers should be more transparent and proactive in communicating their motives and identities. Further implications are discussed.
Weniger anzeigenDas vietnamesische Berlin war lange Zeit hauptsächlich durch zwei Zuwanderungsgruppen gekennzeichnet: die vornehmlich aus Südvietnam geflüchteten sogenannten „Boatpeople“, die Ende der 1970er von der BRD im Rahmen von Kontingentvereinbarungen aufgenommen wurden und die einstigen Vertragsarbeiter*innen, die in den 1980er Jahren in die DDR kamen und nach der Wiedervereinigung zu einem großen Teil in Deutschland blieben. Seitdem wird die Zuwanderung aus Vietnam heterogener, seit Beginn der 2010er Jahre hat sie sich deutlich verstärkt. Diese ‚neue Migration‘, über die bisher kaum etwas bekannt ist, steht im Mittelpunkt der vorliegenden sozialanthropologischen Studie. Mittels eines qualitativen und anwendungsbezogenen ethnografischen ‚multi-sited‘ Ansatzes wurden die dieser Zuwanderung zugrundliegenden Push und Pull-Faktoren und die zentralen Migrationsstrategien untersucht. Daneben wurden die empirisch evidenten Probleme und Belastungen aus der Sicht von Migrant*innen sowie von Fachkräften aus u.a. der Sozialen Arbeit und der Verwaltung analysiert, um ein umfassendes Bild über die Lebenssituation nach Ankunft in Berlin zu erhalten. Ein besonderer Fokus liegt auf den spezifischen Herausforderungen, denen sich (werdende) Mütter und ihre Kinder sowie Auszubildende gegenübersehen.
Weniger anzeigenMolecular isomerization kinetics in liquid solvent depends on a complex interplay between the solvent friction acting on the molecule, internal dissipation effects (also known as internal friction), the viscosity of the solvent, and the dihedral free energy profile. Due to the absence of accurate techniques to directly evaluate isomerization friction, it has not been possible to explore these relationships in full. By combining extensive molecular dynamics simulations with friction memory-kernel extraction techniques we consider a variety of small, isomerising molecules under a range of different viscogenic conditions and directly evaluate the viscosity dependence of the friction acting on a rotating dihedral. We reveal that the influence of different viscogenic media on isomerization kinetics can be dramatically different, even when measured at the same viscosity. This is due to the dynamic solute-solvent coupling, mediated by time-dependent friction memory kernels. We also show that deviations from the linear dependence of isomerization rates on solvent viscosity, which are often simply attributed to internal friction effects, are due to the simultaneous violation of two fundamental relationships: the Stokes-Einstein relation and the overdamped Kramers prediction for the barrier-crossing rate, both of which require explicit knowledge of friction.
Weniger anzeigenHere, we demonstrate the beneficial effect of surfactant-producing pseudomonads on Pantoea eucalypti 299R. We conducted a series of experiments in environments of increasing complexity. P. eucalypti 299R (Pe299R), and Pseudomonas sp. FF1 (Pff1) or Pe299R and surfactant-production deficient Pseudomonas sp. FF1::ΔviscB (Pff1ΔviscB) were co-inoculated in broth, on swarming agar plates, and on plants. In broth, there were no differences in the growth dynamics of Pe299R when growing in the presence of Pff1 or Pff1ΔviscB. By contrast, on swarming agar plates, Pe299R was able to co-swarm with Pff1 which led to a significant increase in Pe299R biomass compared to Pe299R growing with Pff1ΔviscB or in monoculture. Finally in planta, and using the single-cell bioreporter for reproductive success (CUSPER), we found a temporally distinct beneficial effect of Pff1 on co-inoculated Pe299R subpopulations that did not occur in the presence of Pff1ΔviscB. We tested three additional surfactant-producing pseudomonads and their respective surfactant knockout mutants on PE299R on swarming agar showing similar results. This led us to propose a model for the positive effect of surfactant production during leaf colonization. Our results indicate that co-motility might be common during leaf colonization and adds yet another facet to the already manyfold roles of surfactants.
Weniger anzeigenPneumolysin (PLY) is a cholesterol-dependent cytolysin (CDC) from Streptococcus pneumoniae, the main cause for bacterial pneumonia. Liberation of PLY during infection leads to compromised immune system and cytolytic cell death. Here, we report discovery, development, and validation of targeted small molecule inhibitors of PLY (pore-blockers, PB). PB-1 is a virtual screening hit inhibiting PLY-mediated hemolysis. Structural optimization provides PB-2 with improved efficacy. Cryo-electron tomography reveals that PB-2 blocks PLY-binding to cholesterol-containing membranes and subsequent pore formation. Scaffold-hopping delivers PB-3 with superior chemical stability and solubility. PB-3, formed in a protein-templated reaction, binds to Cys428 adjacent to the cholesterol recognition domain of PLY with a KD of 256 nM and a residence time of 2000 s. It acts as anti-virulence factor preventing human lung epithelial cells from PLY-mediated cytolysis and cell death during infection with Streptococcus pneumoniae and is active against the homologous Cys-containing CDC perfringolysin (PFO) as well.
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