Piet Van Mieghem from Delft University of Technology will give an LCN2 seminar on October 28th at 16:00 in room HL214, titled 'Epidemic Spread on Networks'.
Epidemic models are increasingly used in real-world networks to understand diffusion phenomena More info
(such as the spread of diseases, emotions, innovations, failures) or the transport of information (such as news, memes in social on-line networks and flows in functional brain networks). We will mainly focus on Susceptible-Infected-Susceptible (SIS) epidemics on networks. After a brief review of the SIS Markovian process on a graph, we will show why SIS epidemics on networks are so interesting and we will overview our recent developments.
Piet Van Mieghem
Piet Van Mieghem is professor at the Delft University of Technology with a chair in telecommunication networks and chairman of the section Network Architectures and Services (NAS) since 1998. His main research interests lie in the modelling and analysis of complex networks (such as infrastructural, biological, brain, social networks) and in new Internet-like architectures and algorithms for future communications networks.
professor at Leiden University from 1920 to 1946. Being a German citizen, he carried a special ID card. Until October 27 you can vote for this piece of heritage to be ‘Piece of the Year’. The election takes place as part of the History Month.
For Leiden University, Einstein’s ID card is a symbol for the added value of open borders in a knowledge economy. Numerous foreign scientists perform scientific research or lecture at Leiden University, and many Leiden researchers work abroad. This exchange is of major importance for the advancement of science.
Einstein enjoyed visiting Leiden, which he called ‘that delightful place on this parched earth’. Colleagues such as Hendrik Lorentz, Paul Ehrenfest, Willem de Sitter and Heike Kamerlingh Onnes helped him forward and offered new insights. Einstein often stayed at Ehrenfest’s place, which was an exceptional household filled with music and science.
Rigid materials break more easily than floppy ones. This simple observation allows to predict and control the width of cracks. Theoretical understanding of how materials break is useful in for example the production of cars or screens. Publication More info
If you are unlucky enough to have broken a limb at some point in your life, did you wonder why it was the bone that broke, and not the skin? After all, the skin took the first impact. From our intuition we know that rigid materials break more easily than soft ones.
The research group of theoretical physicist Vincenzo Vitelli at Leiden University and his colleagues from the Nagel Lab have exploited this phenomenon to design materials that resist breaking. A rigid material has many bonds and generates a narrow crack in an approximately straight line (see figure 1a). A material composed of fewer bonds is softer, and produces a diffuse failure region: a crack that can be as wide as the sample size (see figure 1b). When that happens the material can resist catastrophic failure thanks to its softness. To discover this, the physicists simulated and built artificial structures—called metamaterials—with tunable numbers of bonds that break in unusual ways. They publish their findings in the journal PNAS.
Earlier, Vitelli’s group published a paper in Nature Materials in collaboration with the Irvine Lab, on the path that a crack follows as it propagates in a curved thin layer. They discovered a remarkable parallel with Einstein’s theory of general relativity, where a ray of light is bent by the curvature of space-time. In the case of fracture, the crack path is bent by the curvature of the underlying surface (see figure 2).
‘When you have a theory on how things break, you can use it to control the properties of real materials,’ says Vitelli. ‘This is potentially useful. For example, you may want to deflect a crack from a portion of a given structure, like the centre of your glasses. Or, to prevent breaking altogether, you can design floppy metamaterials.’
Physics Outreach Officer, Leiden University
arends [at] physics.leidenuniv.nl
+31 (0)71 527 5471
Figure 1. (a)Simulations show a rigid structure with many bonds that generates a straight, narrow crack when broken. (b)In a soft structure with few bonds, the broken bonds (shown in color) are spread over a crack that can be as wide as the system size. (c)An experimental realization of a soft structure, using cellular metamaterial.
Figure 2. (a)Theoretical calculations of the crack path (shown as a black line) on a curved surface on which a crystalline monolayer is deposited. The curved spots are plotted in red and blue. The crack path is bent by these bumpy spots, just like light is bent by the curvature of space-time. (b)Experimental realization of a bent crack in curved space.
The Leidse Instrumentenmakers School (LiS) has received the Leiden erepenning—an honorary medal that is awarded each year during the celebration of the Leids Ontzet to a person or institute that has done a great service to the city of Leiden.
is a professional school for students who learn to design and create precision instruments for science and industry. The school was founded 115 years ago by Leiden physicist and Nobel laureate Heike Kamerlingh Onnes. It still has close connections to the Leiden Institute of Physics. Many graduates work at its department of fine mechanics and Prof. Peter Kes and Dr. Hans Brom are LiS board members.
Since 1997 LiS has had its own building at the Bio Science Park next to the faculty of science. It was elected the best professional school in The Netherlands in 2013 by the Selection Guide MBO. For the past several years, the number of LiS students kept increasing, making it necessary to expand the school. This expansion completed this year, with support of Stichting Utopa, the ministry of OCW, Leiden municipality and Leiden University.
A. Singh, C. Jansen, K. Lahabi, and J.
Aarts (2016) High-Quality CrO2 Nanowires for Dissipation-less Spintronics, Phys. Rev. X, 6, 041012. [DOI]
Moeton M, Stassen OM, Sluijs JA, van der Meer VW, Kluivers LJ, van Hoorn H, Schmidt T, Reits EA, van Strien ME, Hol EM (2016) GFAP isoforms control intermediate filament network dynamics, cell morphology, and focal adhesions., Cell. Mol. Life Sci., 73, 4101-20. [Abstract][DOI][pdf]
24 Oct, 13:15, C06 Gorlaeus Laboratories
Van Marum Colloquium Daniel Bondergaard Trimarco ( DTU ): Direct vacuum inlet system enabling ultra-sensitive in-situ analysis of chemical reaction products information
27 Oct, 16:00, GL, LUMY 04.28
van Leeuwenhoek Lecture on BioScience Alexandre Antonelli (Gothenburg): South America: the world’s largest evolutionary experiment Abstract