Analysis of enhanced stimulated Brillouin scattering in silicon slot waveguides

Stimulated Brillouin scattering has attracted renewed interest with the promise of highly tailorable integration into the silicon photonics platform. However, significant Brillouin amplification in silicon waveguides has yet to be shown. In an effort to engineer a structure with large photon-phonon coupling, we analyzed both forward and backward Brillouin scattering in high-index-contrast silicon slot waveguides. The calculations predict that gradient forces enhance the Brillouin gain in narrow slots. We estimate a currently feasible gain of about $10^{5} \, \text{W}^{-1}\text{m}^{-1}$, which is an order of magnitude larger than in a stand-alone silicon wire. Such efficient coupling could enable a host of Brillouin technologies on a mass-producible silicon chip

Need for narrative

What do consumers need from a narrative? How can videographers satisfy those needs? Through semi-structured interviews with 55 Eurostar passengers from 14 countries, this film documents how people define narratives, why they need them, and how they experience the effects of need for narrative. The adjoining commentary contributes to the development of videography as an attractive method by introducing the videographer’s perspective and elucidating key story elements that can help satisfy viewers’ needs for narrative. The suggested approach maintains the vivid quality of videography and respects its methodological rigour, while increasing its effectiveness in close alignment with a consumer society that visual communication increasingly permeates. As such, the commentary and the film jointly unveil videographers’ etic and viewers’ emic use and evaluation of the videographic method

The means to justify the end: How the way in which decisions to intervene are communicated to users can combat cyber harassment in social media

Cyber harassment does not only have harmful effects for social network sites, because victims tend to exit the service (Avery 2010; Martin and Smith 2008), but the emotional distress brought on by the online aggression has also caused victims to take their own lives (Parker 2012). At the same time, social media users are often upset when network providers intervene with the network and deem such an intrusion an unjust occurrence (Brunk 2012; Davis 2007; Pruitt 2003). The general aim of this paper is to answer the call for “making a difference” research that the Association for Consumer Research North American Conference 2013 has put out. Our intention has been to explore how the aforementioned catch-22 can be resolved through framing the ways in which decisions to intervene are communicated to users. This work expands on existing persuasion and victim identification effects. First, we contend that a decision to intervene based on a story has a more positive effect on user perception that the decision is just than an analytical, factual format. We further distinguish two main components of identity: personal and social (Dollinger et al. 1996; Reid and Deaux 1996). We explore whether the effect of the story over the analytical format holds across both components. Second, we further understanding of the mechanism underlying the presentation format effect. We examine whether the narrative transportation that people experience may lead to a justice perception that the story events imply. Third, we move beyond the prediction that presentation format will be associated with justice perception by exploring an intraindividual moderator that influences this relationship. The current research investigates why self-referencing may lead to either less or more positive justice perceptions under the framework of the story and analytical presentation forma

Unifying Brillouin scattering and cavity optomechanics

So far, Brillouin scattering and cavity optomechanics were mostly disconnected branches of research -- although both deal with photon-phonon coupling. This begs for the development of a broader theory that contains both fields. Here, we derive the dynamics of optomechanical cavities from that of Brillouin-active waveguides. This explicit transition elucidates the link between phenomena such as Brillouin amplification and electromagnetically induced transparency. It proves that effects familiar from cavity optomechanics all have traveling-wave partners, but not vice versa. We reveal a close connection between two parameters of central importance in these fields: the Brillouin gain coefficient and the zero-point optomechanical coupling rate. This enables comparisons between systems as diverse as ultracold atom clouds, plasmonic Raman cavities and nanoscale silicon waveguides. In addition, back-of-the-envelope calculations show that unobserved effects, such as photon-assisted amplification of traveling phonons, are now accessible in existing systems. Finally, we formulate both circuit- and cavity-oriented optomechanics in terms of vacuum coupling rates, cooperativities and gain coefficients, thus reflecting the similarities in the underlying physics.Comment: published manuscript, minor change

Evaluation of the users value of salts against apple scab and powdery mildew for fruit production

The research was aimed at finding anti resistance strategies for Integrated fruit growing. As the salts tested may be approvable for organic farming, the trial results are also of value for the development of scab an mildew control strategies for organic fruit growing. As new fungicides are mainly unisite action fungicides, the problem of fungicide resistance development is becoming more important every year. Combining chemical fungicides, which is the best anti-resistance strategy, is not always possible or recommended in the case when the number of available chemical fungicides are limited or a reduction in fungicide use is asked for. Therefore the use of salts as an anti-resistance strategy was looked upon. The salts evaluated were K(HCO3), KH2PO3, KHPO4 and K2SiO3. When using these salts as an anti-resistance strategy the efficacy obtained when spraying the compounds alone was often to low to be used in rotation with chemical fungicides. Only with K(HCO3)2 a good efficacy can be observed in some years. The variation in efficacy with K(HCO3)2 observed is higher for powdery mildew. K(HCO3)2 can be considered as a ideal product for scab control in organic orchards at moments of low infection risk