Beam-induced Fe nanopillars as tunable domain-wall pinning sites

Focused-electron-beam-induced deposition (FEBID) is employed to create freestanding magnetic nanostructures. By growing Fe nanopillars on top of a perpendicular magnetic domain wall (DW) conduit, pinning of the DWs is observed due to the stray fields emanating from the nanopillar. Furthermore, a different DW pinning behavior is observed between the up and down magnetic states of the pillar, allowing to deduce the switching fields of the pillar in a novel way. The implications of these results are two-fold: not only can 3-dimensional nano-objects be used to control DW motion in applications, it is also proposed that DW motion is a unique tool to probe the magnetic properties of nano-objects

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Integration and differentiation. The impact of educational regimes at secondary level on equity and social mobility in comparative perspective.

Summary This PhD aims to study how the design of the educational system influences the outcomes of different groups and on different time horizons. The outcomes under study range from short-term academic skills over medium-term school drop out to long-term labour market outcomes and participation in life-long learning. Given the broad context in which such a wide array of outcomes has to be situated (e.g. the impact of socio-economic conditions on school dropout, or the impact of labour market regulations on labour market outcomes), this PhD will integrate insights and perspectives from several disciplines. This will result in a typology of different “educational regimes”, i.e. clustered sets of characteristics from both the educational system itself and from other associated spheres (production regime, welfare state, labour market, etc.). Within this framework, the relationship between the characteristics of these regimes and the different outcomes will be explored quantitatively. The broad perspective of this PhD implies that it will be necessary to combine data from a multitude of (international comparable) sources. On one hand, the effect of the educational system on skill levels can be explored using scholastic achievement tests such as PISA (Programme for International Student Assessment: mathematical, scientific and reading literacy of 15 year olds), TIMSS (Trends in International Mathematics and Science Study: mathematical and scientific literacy of 4th and 8th graders), PIRLS (Progress in International Reading Literacy Study: reading literacy of 4th graders). On the other hand, examining medium- and longer term outcomes will have to be examined using data from PIAAC (Programme for the International Assessment of Adult Competencies: mathematical and reading literacy and problem solving skills of adults aged 15-65), the LFS (Labour Force Survey: labour market outcomes of adults aged 15-65) and the AES (Adult Education Survey: lifelong learning participation of adults aged 25-65). Accordingly, different statistical techniques (regression analysis, multi-level analysis, principal component analysis …) will have to be used. A transversal theme in this PhD will be the equity and social mobility perspective: how well do educational systems succeed in providing equal opportunities to different social groups? Finally, policy relevance will be assured by paying special attention to the Flemish education system, with its unique features as well as similarities with other Western countries.status: publishe

Wat kunnen internationale scholierentests ons (niet) leren over het Vlaamse onderwijs?

Eind 2016 werden de resultaten bekendgemaakt van de driejaarlijkse PISA-tests. Met deze tests evalueert de OESO de schoolse vaardigheden (wiskunde, wetenschappen, leesvaardigheid) van 15-jarigen uit meer dan 70 landen. De PISA-cijfers krijgen veel weerklank in de pers en bij beleidsmakers. Ook voor onderzoekers vormen de data een belangrijke bron van informatie. Toch moet met enige omzichtigheid met de resultaten worden omgesprongen. In deze kanttekening geef ik enkele voorbeelden van hoe onderwijskundig onderzoek met de cijfers kan omgaan, maar ook van wat hun beperkingen zijn.status: publishe

De effecten van de structuur van het secundair onderwijs op korte en op lange termijn

De presentatie gaat over de effecten van de structuur van het Vlaamse secundair onderwijs (bijvoorbeeld de leeftijd waarop leerlingen in onderwijsvormen worden gesorteerd en de manier waarop het beroepsonderwijs is uitgebouwd). Gekeken wordt naar zowel uitkomsten op korte termijn (het niveau van de schoolse vaardigheden, het risico op vroege schooluitval) als naar uitkomsten op langere termijn (arbeidsmarktloopbanen, deelname aan levenslang leren). Bijzondere aandacht is er voor de samenhang met de sociale achtergrond van de leerlingen.status: publishe