X-irradiation of cells on glass slides has a dose doubling impact

Immunofluorescence detection of γH2AX foci is a widely used tool to quantify the induction and repair of DNA double-strand breaks (DSBs) induced by ionising radiation. We observed that X-irradiation of mammalian cells exposed on glass slides induced twofold higher foci numbers compared to irradiation with γ-rays. Here, we show that the excess γH2AX foci after X-irradiation are produced from secondary radiation particles generated from the irradiation of glass slides. Both 120 kV X-rays and 137Cs γ-rays induce ∼20 γH2AX foci per Gy in cells growing on thin (∼2 μm) plastic foils immersed in water. The same yield is obtained following γ-irradiation of cells growing on glass slides. However, 120 kV X-rays produce ∼40 γH2AX foci per Gy in cells growing on glass, twofold greater than obtained using cells irradiated on plastic surfaces. The same increase in γH2AX foci number is obtained if the plastic foil on which the cells are grown is irradiated on a glass slide. Thus, the physical proximity to the glass material and not morphological differences of cells growing on different surfaces accounts for the excess γH2AX foci. The increase in foci number depends on the energy and is considerably smaller for 25 kV relative to 120 kV X-rays, a finding which can be explained by known physical properties of radiation. The kinetics for the loss of foci, which is taken to represent the rate of DSB repair, as well as the Artemis dependent repair fraction, was similar following X- or γ-irradiation, demonstrating that DSBs induced by this range of treatments are repaired in an identical manner

Can social robots affect children's prosocial behavior? An experimental study on prosocial robot models

The aim of this study was to investigate whether a social robot that models prosocial behavior (in terms of giving away stickers) influences the occurrence of prosocial behavior among children as well as the extent to which children behave prosocially. Additionally, we investigated whether the occurrence and extent of children's prosocial behavior changed when being repeated and whether the behavior modeled by the robot affected children's norms of prosocial behavior. In a one-factorial experiment (weakly prosocial robot vs. strongly prosocial robot), 61 children aged 8 to 10 and a social robot alternately played four rounds of a game against a computer and, after each round, could decide to give away stickers. Children who saw a strongly prosocial robot gave away more stickers than children who saw a weakly prosocial robot. A strongly prosocial robot also increased children's perception of how many other children engage in prosocial behavior (i.e., descriptive norms). The strongly prosocial robot affected the occurrence of prosocial behavior only in the first round, whereas its effect on the extent of children's prosocial behavior was most distinct in the last round. Our study suggests that the principles of social learning also apply to whether children learn prosocial behavior from robots

Child–robot relationship formation: A narrative review of empirical research

This narrative review aimed to elucidate which robot-related characteristics predict relationship formation between typically-developing children and social robots in terms of closeness and trust. Moreover, we wanted to know to what extent relationship formation can be explained by children’s experiential and cognitive states during interaction with a robot. We reviewed 86 journal articles and conference proceedings published between 2000 and 2017. In terms of predictors, robots’ responsiveness and role, as well as strategic and emotional interaction between robot and child, increased closeness between the child and the robot. Findings about whether robot features predict children’s trust in robots were inconsistent. In terms of children’s experiential and cognitive states during interaction with a robot, robot characteristics and interaction styles were associated with two experiential states: engagement and enjoyment/liking. The literature hardly addressed the impact of experiential and cognitive states on closeness and trust. Comparisons of children’s interactions with robots, adults, and objects showed that robots are perceived as neither animate nor inanimate, and that they are entities with whom children will likely form social relationships. Younger children experienced more enjoyment, were less sensitive to a robot’s interaction style, and were more prone to anthropomorphic tendencies and effects than older children. Tailoring a robot’s sex to that of a child mainly appealed to boys

A social identity perspective on the effect of social information on online video enjoyment

To date, videos are often presented on social media platforms where they are accompanied by social information in the form of user comments. Research suggests that this social information can alter viewers’ video enjoyment. The present study aimed to learn more about two factors that may enhance this effect by conducting a 2x2 between-subjects experiment with a control group (N = 290, Mage = 20.82, SDage = 2.49) in the Netherlands. First, we investigated the role that the source of social information (i.e., in-group vs. out-group) plays in the effect of social information. Second, we explored how writing a comment while watching a video (i.e., commenting vs. no commenting) may alter the effect of the source of social information. Results indicated that social information created by in-group members is more influential than social information created by out-group members. However, writing a comment did not increase viewers’ susceptibility to the effects of social information. These results are discussed in light of the social identity framework, leading to new insights into what may bolster the effect of social information on video enjoyment when individuals watch videos presented on social media

The effects of social information on the enjoyment of online videos: An eye tracking study on the role of attention

Recent experiments showed that the valence of user comments (i.e., social information) presented alongside online videos can alter viewers’ enjoyment of videos. However, it is unclear how much attention video viewers pay to social information and whether the effects found in previous studies occur if participants are not forced to view the social information. Therefore, this study investigated how the valence of social information presented alongside online videos affects viewers’ enjoyment when viewers are free to determine whether and how much attention they pay to social information. Using an eye tracker, we found that most video viewers pay attention to social information which then elicits a valence effect on their enjoyment. Results also showed that a negativity bias occurred: Participants paid most attention to negative social information. Accordingly, the effect of social information on enjoyment was stronger for negative social information. This study is the first to show that social information of online videos affects the experiences of video viewers in settings where viewers are in charge of how much attention they pay to social information