Transient beam loading effects in harmonic rf systems for light sources

Harmonic cavities have been used in storage rings to lengthen bunches and increase beam lifetimes dominated by Touschek scattering. Transient beam loading in the harmonic cavities generated by asymmetries in the fill pattern causes significant variation of the bunch synchronous phase and bunch length along the bunch train when the longitudinal restoring force has been reduced. This results in a significant reduction in the mean bunch lengthening and potential lifetime increase. We describe how beam current modulations give rise to transient effects much larger than expected from the linear model of the beam cavity interaction. We also develop a tracking simulation to predict results and apply this simulation to an analysis of the beam loading transients for the case of passive and active normal and superconducting third harmonic rf systems using Advanced Light Source parameters

Adolescents’ perception of gender differences in bullying

Gender norms are normative societal expectations regarding the behaviors of girls and boys that can guide bullying behavior. As early adolescence is a time when peer relations become increasingly important, it is critical to understand the peer relationships of adolescents and what is considered gender non-confirming behavior. Therefore, the aim of this study is to analyze Swedish girls’ and boys’ perception of gender differences in bullying. Twenty-one Swedish adolescents (8 girls and 13 boys) took part in four focus group discussions separated by boys and girls. Data analysis was conducted using qualitative content analysis. “Expectations and needs to fit the norm” emerged as the main category as all categories emerging from the analysis related to boys’ and girls’ understandings of how expectations, strategies, expressions relating to bullying and the need to belong vary depending on gender. Further, girls and boys expressed admiration for each other's ways of coping with bullying indicating that also coping strategies are associated with expectations based on gender. For schools and adults to be better equipped to meet the needs of girls and boys and understand how these needs are expressed, adolescents voices regarding gender related bullying can be seen as helpful tools to develop strategies to work with gender norms and gender expectations. In light of the results of our study, schools may have work to do when it comes to the awareness of norms and attitudes and how they are expressed as these may be a foundation for bullying, among both staff and students