From Lab-on-chip to Lab-in-App: Challenges towards silicon photonic biosensors product developments

This work presents and evaluates different approaches of integrated optical sensors based on photonic integrated circuit (PIC) technologies for refractive index sensing. Bottlenecks in the fabrication flow towards an applicable system are discussed that hinder a cost-effective mass-production for disposable sensor chips. As sensor device, a waveguide coupled micro-ring based approach is chosen which is manufactured in an 8” wafer level process. We will show that the co-integration with a reproducible, scalable and low-cost microfluidic interface is the main challenge which needs to be overcome for future application of silicon technology based PIC sensor chips

Direct observation and simultaneous use of linear and quadratic electro-optical effects

We report on the direct observation and simultaneous use of the linear and quadratic electro-optical effect and propose a method by which higher-order susceptibilities of electro-optical materials can be determined. The evaluation is based on the separation of the second- and third-order susceptibilities and the experimental technique uses a slot waveguide ring resonator fabricated in integrated photonic circuit technology, which is embedded by a guest-host polymer system consisting of the azobenzene dye Disperse Red 1 in a poly(methyl methacrylate) matrix as an active electro-optical material. The contribution of both effects on the electro-optical response under the influence of static and time-varying electrical fields is investigated. We show that the quadratic electro-optical effect has a significant influence on the overall electro-optical response even with acentric molecular orientated molecules. Our findings have important implications for developing electro-optical devices based on polymer-filled slot waveguides and give rise to advanced photonic circuits. © 2020 IOP Publishing Ltd

The support group approach in the Dutch KiVa anti-bullying programme:Effects on victimisation, defending and well-being at school

Background: School bullying is a wide-spread problem with severe consequences for victims, bullies and bystanders. Schools are strongly encouraged to implement both schoolwide, preventive interventions and reactive measures to handle existing bullying situations. In the Dutch implementation of the KiVa anti-bullying programme, pervasive-bullying situations are addressed according to the support group approach. The support group approach is widely used for addressing bullying situations, but little is known about its effectiveness. Purpose: We investigated the effectiveness of the support group approach in reducing victimisation, increasing defending and improving the victim’s well-being over the course of a school year, over and beyond of the effects of the universal KiVa intervention. Programme description: The support group approach is a non-punitive, problem-solving strategy to address pervasive-bullying situations. In this intervention, trained teachers form a support group that consists of 6–8 children, including the bullies and their assistants, defenders or friends of the victim and prosocial classmates. The purpose of the support group is to create mutual concern for the well-being of the victim and to trigger the bullies’ willingness to alter their behaviour. Sample: We used data from 66 Dutch elementary schools that participated in the KiVa intervention study. Data were collected in October 2012 and 2013, and May 2013 and 2014. The sample used in the analyses consisted of 38 victims for whom a support group intervention was organised (44.7% boy, Mage = 9.24; SDage = 1.20). Design and method: To get insight into the effects above and beyond those of the KiVa programme itself, victims with a support group (N = 38) were matched to similar victims without a support group (N = 571). Statistical analyses were undertaken to examine whether the changes in victimisation, defending and well-being at school differed between the two groups. Result: Victims reported positive effects of the support group approach in reducing victimisation in the short term, but this decrease in victimisation was not lasting over the course of a school year. The intervention also did not improve the victims’ well-being at school in the longer term. Victims with a support group, however, were found to have more defenders at the end of the school year than victims without a support group. Conclusion: The effectiveness of the support group approach in tackling bullying situations appears to fade over time. The findings of this study illustrate that for future evaluations of anti-bullying interventions it is essential to investigate longer term effects

Identifying collaboration dynamics of bipartite author-topic networks with the influences of interest changes

Knowing driving factors and understanding researcher behaviors from the dynamics of collaborations over time offer some insights, i.e. help funding agencies in designing research grant policies. We present longitudinal network analysis on the observed collaborations through co-authorship over 15 years. Since co-authors possibly influence researchers to have interest changes, by focusing on researchers who could become the influencer, we propose a stochastic actor-oriented model of bipartite (two-mode) author-topic networks from article metadata. Information of scientific fields or topics of article contents, which could represent the interests of researchers, are often unavailable in the metadata. Topic absence issue differentiates this work with other studies on collaboration dynamics from article metadata of title-abstract and author properties. Therefore, our works also include procedures to extract and map clustered keywords as topic substitution of research interests. Then, the next step is to generate panel-waves of co-author networks and bipartite author-topic networks for the longitudinal analysis. The proposed model is used to find the driving factors of co-authoring collaboration with the focus on researcher behaviors in interest changes. This paper investigates the dynamics in an academic social network setting using selected metadata of publicly-available crawled articles in interrelated domains of "natural language processing" and "information extraction". Based on the evidence of network evolution, researchers have a conformed tendency to co-author behaviors in publishing articles and exploring topics. Our results indicate the processes of selection and influence in forming co-author ties contribute some levels of social pressure to researchers. Our findings also discussed on how the co-author pressure accelerates the changes of interests and behaviors of the researchers

Microwave spectroscopy on heavy-fermion systems: probing the dynamics of charges and magnetic moments

Investigating solids with light gives direct access to charge dynamics, electronic and magnetic excitations. For heavy fermions, one has to adjust the frequency of the probing light to the small characteristic energy scales, leading to spectroscopy with microwaves. We review general concepts of the frequency-dependent conductivity of heavy fermions, including the slow Drude relaxation and the transition to a superconducting state, which we also demonstrate with experimental data taken on UPd2Al3. We discuss the optical response of a Fermi liquid and how it might be observed in heavy fermions. Microwave studies with focus on quantum criticality in heavy fermions concern the charge response, but also the magnetic moments can be addressed via electron spin resonance (ESR). We discuss the case of YbRh2Si2, the open questions concerning ESR of heavy fermions, and how these might be addressed in the future. This includes an overview of the presently available experimental techniques for microwave studies on heavy fermions, with a focus on broadband studies using the Corbino approach and on planar superconducting resonators.Comment: 11 pages, 6 figures, proceedings of QCnP 201