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Seminars - Summer term 2021

Seminar “Special problems in colloidal physics”

Location: HHU Düsseldorf, Online Seminar
Program:
DateSpeakerTopicTime
Wed 21.04.2021   D. Breoni  t.b.a.  14:30 s.t.
Mon 26.04.2021   R. Wittmann  t.b.a.  14:30 s.t.
Wed 19.05.2021   P. A. Monderkamp  t.b.a.  14:30 s.t.
Wed 26.05.2021   F. Schwarzendahl  t.b.a.  14:30 s.t.
Mon 31.05.2021   A. Zampetaki  Analysis and modelling of few-fish shoals  14:30 s.t.
Mon 07.06.2021   J. Kolker  t.b.a.  14:30 s.t.
Wed 09.06.2021   J. Grauer  t.b.a.  14:30 s.t.
Mon 21.06.2021   A. Sprenger  t.b.a.  14:30 s.t.
Wed 30.06.2021   A. Ider  t.b.a.  14:30 s.t.
Prof. Dr. H. Löwen

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Seminar “Special problems in computer simulation of soft matter”

Location: HHU Düsseldorf, Online Seminar
Program:
DateSpeakerTopicTime
Wed 21.04.2021   D. Breoni  t.b.a.  14:30 s.t.
Wed 19.05.2021   P. A. Monderkamp  t.b.a.  14:30 s.t.
Wed 26.05.2021   F. Schwarzendahl  t.b.a.  14:30 s.t.
Mon 31.05.2021   A. Zampetaki  Analysis and modelling of few-fish shoals  14:30 s.t.
Mon 07.06.2021   J. Kolker  t.b.a.  14:30 s.t.
Wed 09.06.2021   J. Grauer  t.b.a.  14:30 s.t.
Mon 14.06.2021   B. Sanvee  t.b.a.  14:30 s.t.
Wed 23.06.2021   N. Küchler  t.b.a.  14:30 s.t.
Prof. Dr. J. Horbach

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Seminar “Soft Matter”

Location: HHU Düsseldorf, Online Seminar
Program:
DateSpeakerAffiliationTime
Mon 12.04.2021   Jana Lasser  Graz University of Technology and Complexity Science Hub, Vienna, Austria  14:30 s.t.
Jana Lasser: „Assessing the impact of SARS-CoV-2 prevention measures in schools by means of agent-based simulations calibrated to cluster tracing data”
Graz University of Technology and Complexity Science Hub, Vienna, Austria - Seminar@HHUD: 12.4.21 14:30 s.t., Seminarroom Online

How to safely maintain schools open during a pandemic is still controversial. We aim to identify those measures that effectively control the spread of SARS-CoV-2 in schools. By control we mean that each index case infects less than one other person on average.

Here, we analyze Austrian data on 616 clusters involving 2,822 student-cases and 676 teacher-cases with the aim to calibrate an agent-based epidemiological model in terms of cluster size and transmission risk depending on age and clinical presentation. With this model, we quantify the impact of preventive measures such as room ventilation, reduction of class size, wearing of masks during lessons, and school entry testing by SARS-CoV2-antigen tests.

We find that 40% of all clusters involved no more than two cases, and 3% of the clusters only had more than 20 cases. The younger the students, the more likely we found asymptomatic cases and teachers as the source case of the in-school transmissions. Different school types require different combinations of measures to achieve control of the infection spreading: In primary schools, it is necessary to combine at least two of the aforementioned measures. In secondary schools, where contact networks of students and teachers become increasingly large and dense, a combination of three measures is needed.

A sensitivity analysis indicated that the cluster size might increase up to three-fold in secondary schools for virus variants with an increased transmissibility by 50%, and that poorly executed or enforced mitigation measures might increase the cluster size by a factor of more than 30.

Our results suggest that school-type-specific combinations of measures, when strictly adhered to, allow for a controlled opening of schools even under sustained community transmission of SARS-CoV-2. However, large clusters might still occur on an infrequent, however, regular basis. It is shown explicitly that strict adherence to the measures is a necessary condition for successful control.

Assessing the impact of SARS-CoV-2 prevention measures in schools by means of agent-based simulations calibrated to cluster tracing data
Thu 08.04.2021   Michael Klatt  Universität Erlangen-Nürnberg / Universität Saarbrücken  14:00 s.t.
Michael Klatt: „Geometrical and Physical Properties of Designer Materials with Novel Types of Short- and Long-Range Order”
Universität Erlangen-Nürnberg / Universität Saarbrücken - Seminar@HHUD: 8.4.21 14:00 s.t., Seminarroom online

Today, material science offers an unprecedented control of exquisite details in microstructured materials. At the same time, modern research in theoretical physics and mathematics continues to find and understand novel types of short- and long-range order. Unleashing the creativity of these theoretical models, we can turn them into microstructured materials with extraordinary geometrical and physical properties and obtain new functionalities. In this talk, we will discuss three examples of complex spatial structures with remarkable physical properties: (1) a hidden long-range order known as 'hyperuniformity'; (2) network structures with photonic band gaps, and (3) nanorough surfaces that reduce the adhesion forces of bacteria.

Geometrical and Physical Properties of Designer Materials with Novel Types of Short- and Long-Range Order
Thu 18.02.2021   Christian Faber  Deutsches Zentrum für Luft- und Raumfahrt, Köln  14:30 s.t.
Pair correlation function for Many Body Interactions
Wed 06.01.2021   Rahul Gupta  TIFR Hyderabad, India  14:30 s.t.
Active nonreciprocal attraction between motile particles in an elastic medium
Wed 16.12.2020   Claudio Maggi  NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Roma, Italy  14:30 s.t.
Micron-scale active matter: what can we predict?
Mon 07.12.2020   Felix Winterhalter  FAU Erlangen  11:00 s.t.
Investigating the phase behaviour of self-propelled hard spherocylinders
Prof. Dr. Egelhaaf, Prof. Dr. Horbach, Prof. Dr. Löwen

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Colloquia

Location: HHU Düsseldorf, Lecture Hall 5J (Building 25.31 Level 00)
Program:
DateSpeakerAffiliationTime
Thu 09.07.2020   Dr. Selym Villalba-Chávez  Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf  16:30 s.t.
Dr. Selym Villalba-Chávez: „Probing quantum vacuum-like scenarios with high-intensity laser pulses”
Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf - Seminar@HHUD: 9.7.2020 16:30 s.t., Seminarroom Online

Gaining comprehensive insights into the properties of the quantum vacuum is central in our continuous quest for obtaining an in-depth and clear understanding of the fundamental laws of our Universe. While the vacuum in classical physics simply describes a region devoid of matter, the framework of quantum field theory reveals that it is characterized by fluctuations of all plausible and realizable fields in Nature. The talk focuses first on the hitherto unobserved effect of the vacuum decay into electron-positron pairs, paying particular attention to a novel way of amplifying this phenomenon. It will be shown that the principle on which this enhancement relies can be tested via gapped graphene monolayers, and revealed that – although this material resembles the QED vacuum – in some processes its two dimensional structure causes some striking differences between both scenarios. The final part of the talk is oriented to show how experiments involving high-intensity lasers can become a powerful tool to limit the parameter spaces of some dark matter candidates such as axions, hidden-photons and minicharged particles.

The left panel depicts the electron/positron spectrum produced by superimposing a strong time dependent electric field and a fast oscillating wave. A scheme for testing the Breit-Wheeler-like production of massive Dirac pairs in a gapped graphene monolayer is shown in the right panel.

Probing quantum vacuum-like scenarios with high-intensity laser pulses
WE Physik, Heinrich-Heine-Universität Düsseldorf

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Seminar about Bachelor, Master and other Theses from the Institut for Theoretical Physics II

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Link: Physics Colloquium
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