The Department of Science and Environment, Roskilde University, invites applications for a PhD in Applied Mathematics – Adaptive Network Dynamics of Circadian Rhythms in Social Networks from 1 November 2026, or as soon as possible thereafter. The position is time-limited for 3 years (full-time studies).

Description of the PhD project. In this project, we aim to develop mathematical models of adaptive network dynamics with applications to circadian rhythms in social networks. Such dynamics arise when the states of network nodes and the structure of network connections interact and co-evolve — for instance, when individuals' circadian rhythms influence, and are influenced by, their social ties. The core of the project lies at the intersection of dynamical systems theory and network science. Individuals are modeled as oscillators whose phases represent circadian rhythms, coupled through social interactions that themselves evolve over time. This creates a co-evolutionary system in which rhythmic behavior and social structure mutually shape one another. The project will investigate how collective rhythms emerge, persist, or destabilize in such adaptive networks, drawing on bifurcation theory, synchronization phenomena, and network dynamics. The main theoretical direction is the development of a mathematical framework for adaptive network systems, with an emphasis on mathematical modeling and the emergence of low-dimensional dynamics from high-dimensional coupled systems. Complementary directions include data-driven modeling of circadian and social-network time series, and—where feasible—inference of network interaction structure from observational data.

The PhD fellow will join a research group at Section of Mathematics and Physics working on adaptive network dynamics, embedded in a larger mathematical modeling environment at Roskilde University. The project includes opportunities for collaboration with national and international partner institutions such as DTU, Vrije Universiteit Amsterdam, and Lund University, providing opportunities for research visits and exchange of ideas across groups with complementary expertise. The position is part of a larger research project funded by the Novo Nordisk Foundation.

The Doctoral School. The successful candidate will be enrolled in the Doctoral School of Science and Environment in accordance with the rules issued by the Ministry of Technology and Science, Denmark, and additional regulations issued by Roskilde University. The PhD Fellow will be employed in accordance with the agreement between the Ministry of Finance and AC (the Danish confederation of Professional Associations). The Doctoral School of Science and Environment is an international graduate school that covers a broad range of research topics within the areas of science and environment. For more information, see https://ruc.dk/doctoral-school-science-and-environment.

As a PhD student you will be associated with the Section of Mathematics and Physics (IMFUFA).

About the department. The department of Science and Environment is one of four departments at Roskilde University. The Department conducts basic and applied research within mathematics, medical biology, physics, molecular biology, environmental sciences, and chemistry. It offers Bachelor and Master programs across these fields and is characterised by a strong interdisciplinary research culture. Roskilde University is located close to Copenhagen and is easily accessible by public transport (approximately 22 min from Copenhagen Central Station and 30-45 min from Copenhagen airport).

About mathematics at the department. Mathematics at Roskilde University contributes to a broad, research-based education in applied mathematics and scientific modelling. Research and teaching are closely integrated, with an emphasis on problem-oriented and interdisciplinary approaches. The research activities are internationally oriented and address topics of clear societal relevance. Within mathematics, particular strengths include the development and application of mathematical models, especially those based on dynamical systems theory. Application areas cover mathematical biology, in particular areas such as health and medicine, epidemiology, and green and clean technologies.

Responsibilities and tasks

The PhD position is an educational position and the main tasks are in accordance with chapter 3, Ministerial Order on the PhD Programme at the Universities and Certain Higher Artistic Educational Institutions (https://ufm.dk/en/legislation/prevailing-laws-and-regulations/education/files/engelsk-ph-d-bekendtgorelse.pdf).

The PhD candidate’s work will involve research within dynamical systems theory and network theory, with applications in circadian rhythms and social networks.

Qualifications

You must hold a master’s degree or equivalent within mathematics/applied mathematics, theoretical physics or a related engineering discipline. Qualifications within the following areas are required:

Strong knowledge of applied mathematics and dynamical systems theory, bifurcation theory and network theory
Proficiency in scientific programming (e.g., Python, Julia, MATLAB) and symbolic computation.
Excellent written and oral English communication skills.

The ideal candidate is also expected to:

Possess a strong interest in mathematical biology, network theory, and data modeling
Have experience with data science, including time-series analysis and network data
Work independently and lead research activities in close collaboration with the supervisor
Think creatively and help develop new approaches to overcome research challenges
Be highly organized with strong attention to detail and a focus on quality results
Be enterprising, be visible and involved in the department’s activities
Be willing to engage in disciplinary and interdisciplinary collaboration across the department

Assessment

In the assessment regarding employment consideration will be given to;

Relevant Master’s degree or equivalent (according to Danish Qualifications Framework for Higher Education: https://ufm.dk/en/education/recognition-and-transparency/transparency-tools/qualifications-frameworks/other-qualifications-frameworks/danish-qf-for-higher-education?set_language=en&cl=en).
Any additional academic requirements stated in the job advertisement.

In the assessment regarding enrollment, consideration will also be given to the following criteria:

Educational skills and any further professional qualifications
Grades at Master's programme or equivalent education
Quality and relevance of the project description (max 2 pages)
Quality, relevance, and coherence of the methodological and theoretical choices in relation to the research problem
Clarity and focus of the project scope
Ability to complete the PhD project
Research potential, including creativity in approaching scientific challenges and eagerness to learn new fields
Experience in teaching and education (if applicable)
Relevance of the project to the profile of the Doctoral School

Questions

For further information about the postdoc position, please contact PI Associate Professor Erik Andreas Martens, email emartens@ruc.dk or on tel. (+45) 30 64 57 02, or Head of Department Susanne Sørensen, email: susa@ruc.dk on tel. (+45) 4674-2111 / (+45) 6195-1197.

Terms of employment

The employment is on full time, 37 hours per week and you will refer to Head of Department Susanne Sørensen and Associate Professor Erik Andreas Martens.

The position will be filled according to the Agreement between the Danish Ministry of Finance and the Danish Confederation of Professional Associations (AC) and Job Structure for Academic Staff at Universities.

According to the Pay Transparency Directive, the salary ranges for the various job categories at Roskilde University are listed here.

Application procedure

After the deadline for applications the Head of Department will shortlist applicants for assessment with assistance from the recruitment committee including the chairperson of the assessment committee.

Shortly after the application deadline all applicants will be notified whether or not their application has been selected for assessment.

The shortlisted applicants will be informed about the composition of the assessment committee, and each applicant will be given the opportunity to comment on the composition of the committee and - later on - their assessment.

Once the recruitment process is completed, all applicants will be informed of the outcome of their application.

Application

To apply for the position go to www.ruc.dk/en/job/

Only applications in English are accepted.

Applications must include:
1. Cover letter
2. CV
3. Documentation of education including grades from Master’s programme or equivalent
4. Your description of the PhD project
5. Your time schedule of the PhD project
6. If applicable: Documentation for any research experience, work experience or publications.

Please submit your application no later than 04-09-2026.

Material received after this date will not be taken into consideration.

Roskilde University wishes to reflect the diversity of society and welcomes applications from all qualified candidates regardless of personal background.

The hiring process at Roskilde University may include a risk assessment as a tool to identify potential risks associated with new hires, ensuring the safety, compliance, and integrity of the workplace.

PhD in Applied Mathematics – Adaptive Network Dynamics of Circadian Rhythms in Social Networks

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