This study examines the bystander effect in cyberbullying. On the basis of two experiments, we test whether individuals who witness cyberbullying are less willing to intervene when the number of others who have already observed the incident is increased. In addition, we inquire how differently severe cyberbullying incidents affect bystanders' intention to intervene. Our results show that a very severe cyberbullying incident boosts individuals' intention to intervene, mediated by the assessment of the situation as emergency and, in turn, by an increased feeling of responsibility. However, if there is a larger number of bystanders in a cyberbullying incident, rather than just a few, participants feel less responsible to help, and thus, they are less willing to intervene. Keywords Bystander effect, bystander intervention, cyberbullying, diffusion of responsibility, experimentsImagine a user observes that someone is being bullied in an online social networking site and that two others have witnessed the incident. How likely is it that this user will intervene? And now picture that more than a thousand others have already witnessed the

On the basis of experimental data, we study how repetition of a statement affects perceived statement credibility. We identify 2 counteracting effects: The first effect, known as “truth effect,” describes a positive relationship between repetition and statement credibility. People tend to ascribe higher credibility to messages that they repeatedly encounter. In contrast, the second effect occurs when repetition is taken too far. Here, an indirect and negative effect is identified and participants start to perceive the message as a persuasive attempt. This perception triggers reactance, which in turn considerably reduces participants' trust in the source and leads to a significant decrease in the overall credibility of the message. Our results broaden the understanding of the benefits and harms of repeated persuasive messages.

We present experiments on the luminescence of excitons confined in a potential trap at milli-Kelvin bath temperatures under continuous-wave (cw) excitation. They reveal several distinct features like a kink in the dependence of the total integrated luminescence intensity on excitation laser power and a bimodal distribution of the spatially resolved luminescence. Furthermore, we discuss the present state of the theoretical description of Bose-Einstein condensation of excitons with respect to signatures of a condensate in the luminescence. The comparison of the experimental data with theoretical results with respect to the spatially resolved as well as the integrated luminescence intensity shows the necessity of taking into account a Bose-Einstein condensed excitonic phase in order to understand the behaviour of the trapped excitons.

The synthesis of a new side-chain polyrotaxane containing P-dimethyl cyclodextrin rings is described. The rotaxane side groups are attached via amide functions at an aromatic polysulfone. Some characteristics ofthe polyrotaxane are compared with those of a corresponding guest model compound. It is found that the T, value, the solubility in chloroform and acetone, some 'H-NMR shifts and the GPC maximum are significantly influenced by the non-covalently anchored cyclodextrin rings.

We consider a quantum dot, affected by a local vibrational mode and contacted to macroscopic leads, in the nonequilibrium steady-state regime. We apply a variational Lang-Firsov transformation and solve the equations of motion of the Green functions in the Kadanoff-Baym formalism up to second order in the interaction coefficients. The variational determination of the transformation parameter through minimization of the thermodynamic potential allows us to calculate the electron/polaron spectral function and conductance for adiabatic to anti-adiabatic phonon frequencies and weak to strong electron-phonon couplings. We investigate the qualitative impact of the quasiparticle renormalization on the inelastic electron tunneling spectroscopy signatures and discuss the possibility of a polaron induced negative differential conductance. In the high-voltage regime we find that the polaron level follows the lead chemical potential to enhance resonant transport.