Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A model system for group behavior of nanomachines

02.09.2010
Probing for principles underlying flock patterns

For the casual observer it is fascinating to watch the orderly and seemingly choreographed motion of hundreds or even thousands of fish, birds or insects. However, the formation and the manifold motion patterns of such flocks raise numerous questions fundamental to the understanding of complex systems.

A team of physicists from Technische Universitaet Muenchen (TUM) and LMU Muenchen has developed a versatile biophysical model system that opens the door to studying these phenomena and their underlying principles. Using a combination of an experimental platform and theoretical models, more complex systems can now be described and their properties investigated. The Munich researchers report on their findings in the current issue of the renowned journal Nature.

"Everything flows and nothing abides," is a saying ascribed to the Greek philosopher Heraclitus. Large groups of individuals may show collective behavior where the individuals' actions appear to be coordinated or even subordinated to the common good: Flocks of birds move through the air without a conductor, as if they were choreographed, and shoals of fish change their direction instantaneously when a shark appears. Yet science is still puzzled: Do all these systems obey the same universal laws? Does complex group behavior emerge from simple interactions between individuals intrinsically and inevitably? A team of researchers headed by Professor Andreas Bausch, Chair of Biophysics at TUM and Professor Erwin Frey, Chair of Statistical and Biological Physics at LMU, are unraveling the mystery.

The Munich researchers have developed a biophysical model system that makes it possible to carry out targeted high-precision experiments under controlled conditions. To this end, Volker Schaller from the TUM Chair of Biophysics, first author of the study, fixed biological motor proteins to a microscope coverslip in such a way that they could drive filaments of the muscle protein actin, suspended loosely over them, in any direction. The filaments measure about seven nanometers across, i.e. seven millionths of a meter, and are about ten micrometers long, i.e. a ten thousandth of a millimeter. The movement of the filaments is visualized using high-resolution microscopy.

In the experiments described in Nature, the actin filaments began to move as soon as ATP – the fuel for the motor proteins – was added. With low concentrations of actin filaments, the motion remained completely chaotic. Once the density crossed a threshold of five actin filaments per square micrometer, the filaments began to move collectively in larger clusters – with an astonishing resemblance to flocks of birds or shoals of fish. "We can set and observe all relevant parameters in this system," says Schaller. "Using this approach, we can experimentally test the propositions of different theories on self-organization – and that on the tiny scale of 'nanomachines'."

Structures like waves, swirls or ordered clusters seem to appear spontaneously during the experiments. Some of these structures grow to a size of almost one millimeter and remain stable for up to 45 minutes before they dissolve again. Based on these observations, Frey, together with his PhD student Christoph Weber, developed theoretical models to describe the experimental results. With the combination of extensible theoretical models and a precisely controllable experiment, the physicists have set out to tackle more difficult problems and unravel their underlying principles.

"Self-organization phenomena surround us on all levels of our lives," says Bausch. "It begins with traffic jams and the movement of human crowds or the swarming of animals and extends all the way to the organization of biological processes. Important examples are the formation of the cellular cytoskeleton or protein transport facilitated by motor proteins in cells." The underlying principles, though – whether in economic, biological or physical systems – are still among the great open questions of theoretical physics. "For our understanding of nature, as well, there are many fundamental principles yet to be discovered," emphasizes Frey. "However, forecasts should not be applied to the dynamics of human crowds over-hastily – thus far, their complexity is much too great to be captured in simple theoretical models."

The research is funded by the Deutsche Forschungsgemeinschaft (DFG, SFB 863), the cluster of excellence Nanosystems Initiative Munich (NIM), the TUM Institute for Advanced Study at the Technische Universitaet Muenchen, and the Elite Network of Bavaria (CompInt, NanoBioTechnology).

Original publication:

Volker Schaller, Christoph Weber, Christine Semmrich, Erwin Frey und Andreas R. Bausch: Polar patterns of driven filaments. Nature, 2 September 2010, pp 73-77 - doi:10.1038/nature09312

Picture and video credits:
Free pictures: http://mediatum2.ub.tum.de/node?id=994429
Videos of a swirl: http://e27.compint.de/index.php?id=214
Videos of the theory: http://www.theorie.physik.uni-muenchen.de/lsfrey/research/biological_physics/2010_005/movies/
Contacts:
Prof. Andreas Bausch
Technische Universitaet Muenchen
Chair of Biophysics (E 27)
James Franck Str. 1, 85748 Garching
Tel.: +49 89 / 289-12480
Fax: +49 89 / 289-14469
E-Mail: andreas.bausch@ph.tum.de
Internet: www.bio.ph.tum.de
Prof. Erwin Frey
Ludwig-Maxmilians-Universitaet Muenchen
Chair of Statistical and Biological Physics
Theresienstraße 37, 80333 Muenchen
Tel.: +49 89 / 2180-4537
Fax: +49 89 / 2180-4154
E-Mail: frey@lmu.de
Internet: www.theorie.physik.uni-muenchen.de/lsfrey
Technische Universitaet Muenchen (TUM) is one of Europe's leading universities. It has roughly 420 professors, 7,500 academic and non-academic staff (including those at the university hospital "Rechts der Isar"), and 24,000 students. It focuses on the engineering sciences, natural sciences, life sciences, medicine, and economic sciences. After winning numerous awards, it was selected as an "Elite University" in 2006 by the Science Council (Wissenschaftsrat) and the German Research Foundation (DFG). The university's global network includes an outpost in Singapore. TUM is dedicated to the ideal of a top-level research based entrepreneurial university. http://www.tum.de

Andreas Battenberg | EurekAlert!
Further information:
http://www.tum.de

More articles from Physics and Astronomy:

nachricht New thruster design increases efficiency for future spaceflight
16.08.2017 | American Institute of Physics

nachricht Tracking a solar eruption through the solar system
16.08.2017 | American Geophysical Union

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>