Stochastic Systems and Signals

 We are theorists who develop methods of  data analysisfor experiments at the interface between micro- and nano-scale biophysics, life science, and nanotechnology.  


In such experiments thermal noise is ubiquitous, and the process of measurement may introduce localization errors, finite sampling rates, motion blur, etc.  We extract maximal information from noisy data with a combination of physical, mathematical, and statistical modeling and analysis.  

Most of our projects are carried out in close collaboration with experimentalists.

Top: Image analysis resolves a 20 base-pair distance and relative orientation of a DNA strand’s double helix [2]. CenterOptical mapping of DNA [3]. Bottom: Thermophoretic stretching of a single DNA molecule in a nanochannel [4].


Our group has some expertise in analyzing experimental data for super-localization microscopy [1,2], optical mapping of DNA [3], thermophoresis of DNA in confinement [4], cell motility [5,6,7], measurement of single-particle diffusion coefficients [8], proteins diffusing on DNA [9], and optical tweezers [10,11,12].

We teach the course 33647 Computer-based Introduction to Data Analysis for Physics and Nanotechnology and parts of 33472 Laboratory work in Physics and Nanotechnology.

Students are always welcome to contact us to learn more about the possibilities for student projects (MSc, BSc, special courses). Typically, we tailor-make projects to match your and our ambitions and interests.  See also ‘For students’.

REFERENCES (boldface indicates group members at the time the work was done):

  1. K. I. Mortensen, L. S. Churchman, J. A. Spudich and H. Flyvbjerg, Optimized localization analysis for single-molecule tracking and super-resolution microscopy, Nat. Meth. 7, 377 - 381 (2010).
  2. K. I. Mortensen, J. Sung, H. Flyvbjerg, J. A. Spudich, Optimized measurements of separations and angles between intra-molecular fluorescent markers. Nat. Commun. 6, 8621 (2015).
  3. R. Marie, J. N. Pedersen, D.L.V. Bauer, K.H. Rasmussen, M. Yusuf, E. Volpi, H. Flyvbjerg, A. Kristensen, K. Mir: Integrated view of genome structure and sequence of a single DNA molecule in a nanofluidic device, PNAS 110, 4893 (2013).
  4. J.N. Pedersen, C.J. Lüscher, R. Marie, L.H. Thamdrup, A. Kristensen, and H. Flyvbjerg, Thermophoretic Forces on DNA Measured with a Single-Molecule Spring Balance, Phys. Rev. Lett. 113, 268301 (2014).
  5. D. Selmeczi, S. Mosler, P. H. Hagedorn, N. B. Larsen, and H. FlyvbjergCell Motility as Persistent Random Motion: Theories from Experiments. Biophys. J. 89, 912-931 (2005).
  6. L. Li, Edward C. Cox, and H. Flyvbjerg. "Dicty Dynamics": Dictyostelium motility as persistent random motionPhys. Biol.  8  046006 (2011).
  7. J.N. Pedersen, L. Li, C. Grădinaru, R.H. Austin, E.C. Cox, and H. Flyvbjerg, How to connect time-lapse recorded trajectories of motile microorganisms with dynamical models in continuous time, Phys. Rev. E 94, 062401 (2016).
  8. C. L. Vestergaard, P. C. Blainey, and H. FlyvbjergOptimal estimation of diffusion coefficients from single-particle trajectories,  Phys. Rev. E 89, 022726 (2014). Featured as Editors' Suggestion in Phys. Rev. E.
  9. C. L. Vestergaard, P. C. Blainey, and H. Flyvbjerg. Single-particle trajectories reveal two-state diffusion-kinetics of hOGG1 proteins on DNANucl. Acids Res., (2018).
  10. J. Sung, S. Nag, Kim I. Mortensen, C. L. Vestergaard, S. Sutton, K. Ruppel, H. Flyvbjerg & J.A. Spudich, Harmonic force spectroscopy measures load-dependent kinetics of individual human β-cardiac myosin molecules, Nature Communications 6, 7931 (2015).
  11. K. Berg-Sørensen and H. Flyvbjerg, Power spectrum analysis for optical tweezers, Rev. Sci. Instr. 75, 594 (2004).
  12. S. F. Tolic-Nørrelykke, E. Schäffer, J. Howard, F. S. Pavone, F. Jülicher, and H. FlyvbjergCalibration of optical tweezers with positional detection in the back-focal-plane,  Rev. Sci. Instrum. 77, 103101 (2006).



Henrik Flyvbjerg
DTU Health Tech
+45 45 25 63 23


Kim Mortensen
Senior Researcher
DTU Health Tech
+45 45 25 63 09