2017 Impact factor 1.536
Condensed Matter and Complex Systems

News / Highlights / Colloquia

EPJ B Highlight - Bottom-up insight into crowd dynamics

In the simulations, agents are grouped into six zones based on their initial distances from the exit. © Viswanthan et al.

A new study proposes a method for quantitatively analysing the relative value of models for crowd dynamics prediction, following individual movement

Stampedes unfortunately occur on too regular a basis. Previously, physicists developed numerous models of crowd evacuation dynamics. Their analyses focused on disasters such as the yearly Muslim Hajj or of the Love Parade disaster in Germany in 2010. Unfortunately, the casualties at these events may have been linked to the limitations of the crowd dynamics models used at the time. Now, a new study outlines a procedure for quantitatively comparing different crowd models, which also helps to compare these models with real-world data. In a paper published in EPJ B, Vaisagh Viswanathan, a PhD student from Nanyang Technological University in Singapore, and colleagues have demonstrated that these crowd evacuation dynamics models are a viable decision-making tool in safety preparation and planning concerning real-world human crowds.

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EPJ B Colloquium - Thermodynamics and kinetics properties of condensed matter derived through the properties of an intrinsic defect

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Elementary jump of an interstitialcy in an fcc Lattice. Open circles (red), before jump; closed circles (blue), after jump (Fig. 6 from the paper).

The theory of interstitialcy for simple condensed matters is a theory formulated by Andrew V. Granato enable the determination of the thermodynamic and kinetic properties of simple liquids and glasses. In a new Colloquium in EPJ B the author provides a simpler, more physical and compelling version of his interstitialcy theory. In addition, the results of computer simulations, together with direct and indirect experimental evidence, are updated and reviewed. In addition, the results of computer simulations, together with direct and indirect experimental evidence, are updated and reviewed. The connection between theory and experiment for some of the more notable properties of simple condensed matter is discussed. The direct visual observation of interstitial diffusion to the surface of irradiated platinum thin films near 20K by Morgenstern, Michely and Comsa provides compelling evidence for the interstitialcy theory presented herein.

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EPJ B Highlight - Quasi-particle swap between graphene layers

Sketch of the two twisted graphene layers. © M. Sarrazin et al.

Equations used to describe parallel worlds in particle physics can help study the behaviour of particles in parallel graphene layers

Belgian scientists have used a particle physics theory to describe the behaviour of particle-like entities, referred to as excitons, in two layers of graphene, a one-carbon-atom-thick honeycomb crystal. In a paper recently published in EPJ B, Michael Sarrazin from the University of Namur, and Fabrice Petit from the Belgian Ceramic Research Centre in Mons, studied the behaviour of excitons in a bilayer of graphene through an analogy with excitons evolving in two abstract parallel worlds, described with equations typically used in high-energy particle physics.

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EPJ B Highlight - A step closer to composite-based electronics

An illustration of a small portion of a square lattice. © I. Balberg et al.

A new study demonstrates that electrical resistivity obeys a staircase-like dependence on the conducting particle concentration in composite materials

Composite materials are of increasing interest to physicists. Typically, they are made of electrically conducting elements - such as spherical metallic or elongated carbon particles - embedded in an insulating glass or a polymer matrix. Their controllable electrical resistivity combined with their light and flexible properties, makes them suited for applications in flexible electronics. Now, a theoretical model, confirmed experimentally, elucidates how electrical resistivity varies with the concentration of the particles in these composite materials. These findings have been published in EPJ B, by Isaac Balberg and colleagues from the Hebrew University in Jerusalem, Israel.

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EPJ B Highlight - Revisiting quantum effects in MEMS

Example of MEMS. © United States Government Work

New calculations shows that the influence of quantum effects on the operating conditions of nanodevices has, until now, been overestimated

Micro- and nano-electromechanical devices, referred to as MEMS and NEMS, are ubiquitous. These nanoscale machines with movable parts are used, for example, to trigger cars’ airbags following a shock. They can also be found in smartphones, allowing them to detect how to adequately display the screen for the viewer. The trouble is that, as their size decreases, forces typically experienced at the quantum level start to matter in these nanodevices. Mexican physicists have studied the mechanical and electrical stability of MEMS and NEMS, depending on the plate thickness and the nature of the material used. The results have now been published in EPJ B by Raul Esquivel-Sirvent and Rafael Perez-Pascual from the National Autonomous University of Mexico, in Mexico City.

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EPJ B Highlight - Numerical validation of quantum magnetic ordering

This study focuses on the (3+1)-dimensional spatially anisotropic quantum Heisenberg model. © M.-T. Kao et al.

Numerical simulations designed to confirm the magnetic characteristics of 3D quantum materials largely match the theoretical predictions

A new study set out to use numerical simulations to validate previous theoretical predictions describing materials exhibiting so-called antiferromagneting characteristics. A recently discovered theory shows that the ordering temperature depends on two factors—namely the spin-wave velocity and the staggered magnetisation. The results, largely consistent with these theoretical predictions, have now been published in a paper in EPJ B by Ming-Tso Kao and Fu-Jiun Jiang from the National Taiwan Normal University, in Taipei.

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EPJ B Colloquium - Conjugated polymer-wrapped carbon nanotubes: physical properties and device applications

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s-SWNTs/PCBM heterojunction (Fig. 9c modified from Ref. [77] of the paper).

This EPJ B Colloquium presents an overview of the preparation method and physical properties of a new hybrid system consisting of single-walled carbon nanotubes (SWNTs) wrapped in conjugated polymers. The technique, which was first demonstrated in 2007, has attracted great interest owing to the high purity of the resulting semiconducting SWNTs and the possibility of applying them in electronic devices. Here, the authors review recent progress in the preparation of these nano-hybrids, their photophysical properties, and their applications in field-effect transistors and photovoltaic devices.

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EPJ B Highlight - Green photon beams more agile than optical tweezers

Charge-density computation of butane molecules.

A new manipulation tool exploits the fact that when light interacts with matter, it creates a force that produces material properties in macromolecules and biological cells

Romanian scientists have discovered a novel approach for the optical manipulation of macromolecules and biological cells. Their findings stem from challenging the idea that visible light would induce no physical effect on them since it is not absorbed. Instead, Sorin Comorosan, working as physicist at the National Institute for Physics and Nuclear Engineering based in Magurele, Romania, and as a biologist at the Fundeni Clinical Institute, Bucharest, Romania, and colleagues had the idea to use green photon beams. With them, it is possible to perform optical manipulation of macrostructures, such as biological proteins, with greater precision than with optical tweezers made from focused laser beams.

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EPJ B Highlight - Atom-based analogues to electronic devices

Spectral functions of the first (left panel) and the second (right panel) quantum dot.

New research gives a theoretical explanation as to how transport of single atoms is made possible through a chain of quantum dots

Scientists have pushed back the boundaries of atom-based transport, creating a current by charac-terising the many-body effects in the transport of the atoms along a periodic lattice. This work by Anton Ivanov and colleagues from the Institute for Theoretical Physics, at the University of Heidel-berg, Germany, adopted a new analytical approach before comparing it to approximate numerical simulations, and is reported in a paper recently published in EPJ B.

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EPJ B Highlight - Studying emotions causing opinions to change

Example of evolution of agent opinions.

Physicists can use their tools to help understand how, in real life, opinions form and change by modelling the complex interactions between information and emotion

Social phenomena fascinate with their complexity, but are not easily understood. Pawel Sobkowicz, an independent researcher based in Warsaw, Poland, has developed a model to study the dynamic of standard people, called ‘agents’, and their response to a given piece of information, depending on their emotional state. In a study just published in EPJ B, the author shows that opinion dynamics differ depending on whether the agent is agitated or not.

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Acting EiC: Wenhui Duan

Executive Editors:
B.K. Chakrabarti, W. Duan, E. Hernandez, H. Rieger
I am naturally indebted to you and the referees who contributed to this success with your time and constructive advice.

Hamid Assadi

ISSN (Print Edition): 1434-6028
ISSN (Electronic Edition): 1434-6036

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