Pushing the boundaries of quantum theories – that’s exactly what the physicists at Leiden University excel at. Researchers in Leiden are launching eight new quantum research projects as part of the Quantum Limits consortium.

How do tax treaties have to be explained and implemented, and what role does the supranational regulatory process play in this? Which objectives are meant to be used in establishing tax regulations and to what extent are such legislative practices undertaken in a goal-oriented manner?.

Atherosclerosis is a chronic inflammatory disease, and vaccination may be an attractive method to induce long lasting protection against endogenous factors that contribute to the development of atherosclerosis. We have shown that for example vaccination against modified LDL or interleukin-12 limits…

Central Limit Theorem associated to a particular case of ergodic total automorphisms. Finally, Chapter 6 proves that the isoperiodic foliation is connected for a meromorphic differential with three poles on a torus.

For more information regarding ongoing research projects, please contact Prof. Johan Kuiper.

Many of the most acute problems we face today are global: they transcend national boundaries, they put the future of society and even humanity at peril, and they can only be addressed through international cooperation.

This dissertation is about Bayesian learning from data. How can humans and computers learn from data?

Reconfigurations of Practice, Community and Authority in Contemporary Aceh

‘It became very clear that Brazilian legislative policy was frail, obsolete and unreliable,’ says Felipe de Paula. He defended his dissertation on the limits and possibilities of legislative policy in Brazil on Tuesday 27 March 2018.

Tomography is a powerful technique to non-destructively determine the interior structure of an object.Usually, a series of projection images (e.g.\ X-ray images) is acquired from a range of different positions.

This thesis is a collection of theoretical works aiming at adjusting quantum algorithms to the hardware of quantum computers.

The increase in the European Union's executive powers in the areas of economic and financial governance has thrown into sharp relief the challenges of EU law in constituting, framing, and constraining the decision-making processes and political choices that have hitherto supported European integration.…

On 10 February 2022, Christian Mommers defended the thesis 'Voluntary return and the limits of individual responsibility in the EU Returns Directive'. The doctoral research was supervised by Prof. P.R. Rodrigues and Prof. P. Boeles.

This article discusses the impact of symbolic gender representation on the willingness of citizens to coproduce.

Can process-oriented dynamic testing be applied to everyday educational practice?

The making of sacrifices seems part and parcel of any elite sportsperson’s life. Remarkably, the insights that we find in the current literature in social sport studies are not able to make sense of the references to sacrifice in the data that emerged in the context of this study on the social significance…

This study investigates how two social and political developments, in the UK and Germany, impacted on the experiences of minorities and the attitudes of majorities vis-à-vis tolerance in those two countries. The results provide a thought-provoking picture of the views of minority and majority groups…

Promotor: Prof.dr. T.H.W. Bäck

From William Shakespeare to Marilynne Robinson, A Literary History of Reconciliation is the first study to examine representations of interpersonal reconciliation in work of literature across a long-term period, from the early seventeenth century to the present day, focusing on how these representations…

Where does Europe begin and end? How have the European Union and its precursors decided which countries are eligible to join the community and which are not? Few issues are more hotly debated, more important for the course of European integration, or more consequential for individuals in and around…

In this dissertation, we work towards an experiment in which we aim to bring a micrometer sized magnet at the tip of a soft cantilever into a superposition.

This article examines the effects of introducing proportional representation (PR) in Polish local elections on women’s political representation.

Monica Kaminska, Dennis Broeders and Fabio Cristiano have contributed a chapter to the proceedings of the 13th International Conference on Cyber Conflict (CyCon 2021), which gathers 20 articles from the law, technology and strategy domains.

The Ministry of Health, Welfare and Sport in the Netherlands is being flooded with applications for information under the Dutch Public Access to Government Information Act (WOB) and according to Minister Hugo de Jonge is unable to provide the information on time. News programme Nieuwsuur has been waiting…

Leiden biologist Suzanne Lommen and an international team of scientists have investigated how a beetle can reduce hay fever in Europe. Locally, the beetle is even able to stop pollen production in a plant that causes allergic reactions. Publication in Nature Communications on April 21.

Can astronomers mitigate climate change? This is what Leiden astronomer Leonard Burtscher and his colleagues discussed at the annual meeting of the European Astronomical Society. For the second year in a row, the meeting was online. And according to Burtscher, it should stay that way. During a special…

The risk that conspiracy theories could incite a broad movement against the established political order is virtually non-existent. This is what researcher Jelle van Buuren of the Institute of Security and Global Affairs concluded in his PhD dissertation.

The small quantum world and our world of perception obey different laws of nature. Leiden physicists search for the border between both worlds. In an article published soon in Physical Review Letters they set an upper limit.

Leiden University no longer wishes to collaborate with fossil fuel partners that are not demonstrably committed to achieving the Paris Agreement targets. Exceptions will be made only if a collaboration demonstrably contributes to the energy transition. This proposal by the Executive Board was discussed…

VVD party members last week voted in favour of the new distribution law, which could oblige municipalities to accommodate asylum seekers. This happened after Prime Minister Rutte pledged to work on curbing the influx of asylum seekers. To what extent can he deliver on that promise?

The strikes by Dutch rail operator ProRail are not predicted to end any time soon, and that will cause considerable inconvenience for travellers. ‘They may have already reached the limits of what’s allowed,’ says Barend Barentsen, Professor of Labour Law, in Dutch daily newspaper ‘de Volkskrant’.

News articles have only a limited influence on the course of legislative processes. This is the finding of political science expert Lotte Melenhorst in her PhD dissertation. Defence 21 March.

Several Dutch universities have said they do not want foreign student numbers to grow any more in some of their degree programmes. They are reaching maximum capacity. We are also alert to this in Leiden, but I see many positive aspects to the intake of international students.

Authors: Pierre-Bruno Ruffini and Olga Krasnyak

The call for a social media ban for children is louder than ever. Professor of Children's Rights Ton Liefaard argues in ‘Trouw’ newspaper that this would be unwise. 'For children, online and offline aren't different worlds'.

The municipality of Utrecht is appealing to the Council of State following the decision by Dutch Minister of the Interior and Kingdom Relations Hugo de Jonge to cancel an initiative that would increase the asset limit for tax remission. Utrecht Nieuws NL reports that through the initiative, the municipality…

A common assumption in chemistry is that the coordination number of a catalyst's surface determines the reactivity of the reaction it catalyses. Strikingly, Leiden chemists have now proven that this is not true for nature’s most simple chemical reaction: the dissociation of hydrogen. The researchers…

As with other dual-use technologies, non-lethal drone applications are increasingly becoming both a cause for concern and an exciting area of development.

This dissertation consists of two parts, each of which considers a different research area related to random interval maps. In the first part we are interested in random interval maps that are critically intermittent.

It is difficult to imagine a society other than a hierarchical nation-state. This is in part because we neglect alternative forms from the past, argues archaeologist Lewis Borck in the Journal of Contemporary Archaeology.

The EU Return Directive gives migrants residing unlawfully in the European Union the option to leave voluntarily. This is to avoid detention and forced expulsion. But the directive is too vague and can lead to unfair procedures and even human rights violations, PhD candidate Christian Mommers conclu…

Masses of hamburgers, steaks, cheese and a lot of eggs: Americans love their animal products. But researcher Oliver Taherzadeh discovered that only a relatively small group of high-volume consumers need to modify their diet to achieve an enormous environmental gain.

Opting more often for mocktails or soft drinks rather than beer or wine, talking to others about their drinking and pointing out the ban on drugs. Leiden University’s new covenant on alcohol and drugs for study associations encourages providing more alcohol-free alternatives.

Science education project Space Awareness engaged 230,000 people in 68 countries with the excitement and challenges of space sciences and technologies. After three years, the project coordinated by Leiden Observatory came to an end in March and has now been evaluated.

This thesis explores Breaking of Ensemble Equivalence (BEE) in random graph models by examining the spectral properties of adjacency matrices. The goal is to identify spectral characteristics that differentiate random graph ensembles, enhancing the understanding of complex network structures and beh…

Vaccination is the most effective method to prevent influenza infection. However, current influenza vaccines have several limitations. Relatively long production times, limited vaccine capacity, moderate efficacy in certain populations and lack of cross-reactivity are important issues that need to be…

The subject of this thesis, ‘Approach to Markov Operators on Spaces of Measures by Means of Equicontinuity’, combines an analytical and probabilistic approach to Markov operators.