An algorithm is discussed to compute the exponential representation of principal units in a finite extension field F of the p-adic rationals.

The unit residue group, to which the present thesis is devoted, is defined using the norm-residue symbol, which Hilbert introduced into algebraic number theory in 1897.

PhD Defence

Promotores: Prof.dr.G.R. de Snoo and Dr. R. Heijungs

What are the key issues in conducting LCA of bioenergy systems? What is the environmental sustainability status of second generation bioethanol? How much would the final results of biogenic carbon neutrality assumptions deviate from the true values based on a complete inventory? How to assess the impact…

A research program that focuses on the development and implementation of cyber norms.

A discourse on international cyber norms has emerged ever since the United Nations Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security (UN GGE) recommended eleven norms on responsible state behaviour in cyberspace.

PhD Defence

The Mathematical Institute is responsible for the research and education in mathematics and statistics at Leiden University.

Ilina Georgieva published an article in the journal Contemporary Security Policy on the norm-setting role of intelligence agencies.

The United Nations Office for Disarmament Affairs (UNODA) has published the 2017 issue in their Civil Society and Disarmament series, titled Voluntary, Non-Binding Norms for Responsible State Behaviour in the Use of Information and Communications Technology: A Commentary. The series aims to provide…

Are there general principles or values that should govern our actions as moral agents and/or as political subjects?

An experimental comparison of the impact of liberal norms on a population residing and socialised within a democracy (the Netherlands) with a population in an autocracy (China) and their respective supports for war with another state shows that the level of liberal norms in the democratic experimental…

Vinasse is a major by-product generated by the sugarcane biofuel industry. It is a source of microbes, nutrients and organic matter and often it is recycled as fertilizer.

Language Use, Usage Guides and Linguistic Norms will be of interest to scholars of language use in both the past and the present, as well as to anyone interested in the interplay between actual language use and prescriptive attitudes towards language.

On a referendum held on May 21, 2006, 55.5% of voters in Montenegro voted in favor of their country’s independence. While in numerical terms the outcome shows overwhelming support for independent Montenegro, from a normative standpoint it was a narrow win. The normative framework that regulated rules…

Article by Leiden University political scientist Daniel Thomas about shifting norms for membership in international organisations.

The Leiden University’s Program for Cyber Norms, a research platform to investigate the development and implementation of law and policy applicable to uses of ICTs, in cooperation with the think-tank ICT4Peace conducted a global open consultation on how to implement the UN Group of Governmental Experts’…

In this research we have studied how teaching graphing formulas by hand (i.e. sketching a graph of a formula) could promote grade 11- and 12-students’ symbol sense.

In this article in International Affairs, Saskia Postema and Jan Melissen examine Chinese celebrities' UN-affiliated Weibo activism in the context of China's increasing engagement in the United Nations, which coincides with a shrinking domestic public sphere under Xi Jinping's leadership.

This article traces the evolution of interpretations of international law and international cyber norms on responsible state behaviour in cyberspace by reassessing five major – and allegedly state-led – cyber operations: Stuxnet 2010; Belgacom 2013-2014, the Ukrainian power grid 2015, the US presidential…

This research project focuses on the relation between identity marks and writing.

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…

This project aims to explore, in general, what explains civil servants’ attitudes and behavior, and, in particular, why some civil servants are more committed to professional norms and public service values – such as impartiality, equity, efficiency, and innovation – than others.

Studies on representative bureaucracy have often confirmed the positive performance effects of bureaucracies mirroring the demographic characteristics of their clientele. However, little is known about the underlying individual level mechanisms leading to these outcomes.

Large numbers of children all over the world face significant health risks, such as infectious and chronic diseases, malnutrition, injuries and the consequences of natural disasters, protracted armed conflicts and poverty.

This project focuses on Dutch registration of land and people in rural Sri Lanka. How did the practice of “fixating” the fluid social relations and dynamic daily practices into categories affect family strategies of reproduction and survival?

In this work we describe three methods to improve the performance of Quantum Field Theory calculations.

Tracking early human behaviour through plant processing and -exploitation.

Interview with prof.dr. Dennis Broeders in magazine De Veiligheidsdiplomaat (The Security Diplomat)

This year The Hague Program for Cyber Norms organises the first conference of an annual series to encourage academic diversity in the study of cyber security. The theme is Responsible Behavior in Cyberspace. The conference will take place in The Hague from 5 to 7 November 2018. Deadline submission of…

The Hague Program for Cyber Norms organises the second conference of an annual series to encourage academic diversity in the study of cyber security. The theme is 'Dealing with Uncertainty'. The conference will take place in The Hague on 5 and 6 November 2019. Deadline submission of extended abstracts…

Prof.dr. Annelou van Gijn has obtained a Marie Curie subsidy for research on wetland activity patterns in Mesolithic Northwest Europe. This funding has been used to employ the researcher dr. Aimée Little. The project will commence in November 2011.

Commercial enterprises who want to make use of the expertise and facilities are referred to LAB , the commercial unit responsible for specialized laboratory work.

We are delighted to welcome Josh Gold as Visiting Fellow of The Hague Program for Cyber Norms at Leiden University’s Institute of Security and Global Affairs from 1 - 9 May.

How did people experience Islam on a day-to-day basis in the early centuries of Islam? That's where the papyri come in, says professor of Arabic Petra Sijpesteijn in the fourth video of the Leiden | Islam interview series.

We are delighted to welcome Arun Sukumar as Visiting Fellow of The Hague Program for Cyber Norms at Leiden University’s Institute of Security and Global Affairs from 30 October - 30 November.

The Leiden University’s Program for Cyber Norms, a research platform to investigate the development and implementation of law and policy applicable to uses of ICTs, in cooperation with the think-tank ICT4Peace conducted a global open consultation on how to implement the UN Group of Governmental Experts’…

We are delighted to welcome Caitriona Heinl as Visiting Fellow of The Hague Program for Cyber Norms at Leiden University’s Institute of Security and Global Affairs from 22 January till 16 February 2018.

We are delighted to welcome Dr. Danny Steed and Dr. Kubo Mačák as Visiting Fellows of The Hague Program for Cyber Norms at Leiden University’s Institute of Security and Global Affairs from 1 Apr 2019 - 26 Apr 2019.

A century ago, the French linguist Ferdinand de Saussure proposed that the relationship between the sound of a word and its meaning is fundamentally arbitrary. In a new study, a team of researchers from European and American research institutions, including Søren Wichmann from Leiden University Centre…

Pectin is a plant cell wall polysaccharide made of mainly D-galacturonic acid (GA) subunits. The potency of the filamentous fungus Aspergillus niger to naturally secrete high amounts of pectinases to degrade pectin has been utilized for the industrial production of pectinases.

Russell Buchan will be a Visiting Fellow at The Hague Program for Cyber Norms at Leiden University’s Institute of Security and Global Affairs from 19 August to 13 September.

On 14 May 2020, Pieter Rustenburg defended his thesis 'Een algemene normtheorie toegepast op open normen in het belastingrecht'. The doctoral research was supervised by Prof. A.O. Lubbers and Prof. J.L.M. Gribnau.

When oil is harvested from the seeds of the oil palm tree, the fruit residue can be used to make bio-ethanol. However, it can also be used as a fertilizer on palm tree plantations; which option is best for the environment? Edi Wiloso compared the two green options at the Institute of Environmental Sciences…