2019 Impact factor 3.000

News

EPJ E Highlight - Building better diffusion models for active systems

Deviating from Brownian motion.

Modifications to existing theories have enabled researchers to better understand and model the dynamics of systems which don’t obey conventional laws of diffusion

In normal circumstances, particles will follow well-established random motions as they diffuse through liquids and gases. Yet in some types of system, this behaviour can be disrupted – meaning the diffusion motions of particles are no longer influenced by the outcomes of chains of previous events. Through research published in EPJ E, Bernhard Mitterwallner, a Ph.D. student in the team of Roland Netz at the Free University of Berlin, Germany, has developed new theories detailing how these unusual dynamics can be reproduced in generalised mathematical models.

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EPJ E Highlight - Modelling microswimmers for drug delivery

Streamlines of the fluid flow induced by a single point force (Stokeslet) representing a microswimmer inside a freely moving viscous drop.

Mathematical models of the motion of cells in viscous liquids that show how this motion is affected by the presence of a surfactant coating have applications in the design of artificial microswimmers for targeted drug delivery, micro-surgery and other applications.

Many types of motile cells, such as the bacteria in our guts and spermatozoa in the female reproductive tracts, need to propel themselves through confined spaces filled with viscous liquid. In recent years, the motion of these ‘microswimmers’ has been mimicked in the design of self-propelled micro- and nano-scale machines for applications including targeted drug delivery. Optimising the design of these machines requires a detailed, mathematical understanding of microswimmers in these environments. A large, international group of physicists led by Abdallah Daddi-Moussa-Ider of Heinrich-Heine-Universität Düsseldorf, Germany has now generated mathematical models of microswimmers in clean and surfactant-covered viscous drops, showing that the surfactant significantly alters the swimmers’ behaviour. They have published their work in EPJ E.

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EPJ B Highlight - Investigating optical activity under an external magnetic field

A schematic of a monolayer of black phosphorus under the influence of an external magnetic field. (Liu. C., Wu. F., Jiang. Q., Chen. Y., Yin. C.)

New research reveals that applying a magnetic field to a chiral metamaterial can change the way it polarises light.

Optical activity in chiral molecules has become a hot topic in physics and optics, representing the ability to manipulate the polarized state of light. Understanding how molecules rotate the plane of plane-polarized light has widespread applications, from analytic chemistry to biology and medicine — where it can, for example, be used to detect the amount of sugar in a substance. A new study published in EPJ B by Chengping Yin of the Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China, aims to derive an analytical model of optical activity in black phosphorous under an external magnetic field.

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EPJ D Highlight - Identifying biomolecule fragments in ionising radiation

Glycine fragments during heavy ion bombardment. Source

Research published in EPJ D has revealed how the nature of biomolecule fragmentation varies with the energies of electrons produced when living cells are irradiated with heavy ions.

When living cells are bombarded with fast, heavy ions, their interactions with water molecules can produce randomly scattered ‘secondary’ electrons with a wide range of energies. These electrons can then go on to trigger potentially damaging reactions in nearby biological molecules, producing electrically charged fragments. So far, however, researchers have yet to determine the precise energies at which secondary electrons produce certain fragments. In a new study published in EPJ D, researchers in Japan led by Hidetsugu Tsuchida at Kyoto University define for the first time the precise exact ranges in which positively and negatively charged fragments can be produced.

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EPJ C Highlight - Weak equivalence principle violated in gravitational waves

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Gravitational waves influence Fisher information. MoocSummers, wikimedia commons (CC BY-SA 4.0)

Calculations reveal that a key principle of classical physics is broken by quantum particles as they pass through ripples in spacetime.

The Weak Equivalence Principle (WEP) is a key aspect of classical physics. It states that when particles are in freefall, the trajectories they follow are entirely independent of their masses. However, it is not yet clear whether this property also applies within the more complex field of quantum mechanics. In new research published in EPJ C, James Quach at the University of Adelaide, Australia, proves theoretically that the WEP can be violated by quantum particles in gravitational waves – the ripples in spacetime caused by colossal events such as merging black holes.

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EPJ D Topical review - Confining and compressing the atom

Illustrating the effect of confinement within spheres of different radius on an atomic wavefunction (the example chosen is for Calcium)

A new Review article in EPJD from Jean-Patrick Connerade (Imperial College London and European Academy EASAL Paris) presents a brief introduction to the physics of confined atoms. The subject has acquired importance in the areas of endohedral fullerenes, quantum dots, bubbles in solids (e.g. helium bubbles in the walls of nuclear reactors), atoms trapped in zeolites, impurities in solids, etc. Confining and compressing the atom is considered from the outset as a problem of fundamental atomic physics inherent to basic models such as the Thomas-Fermi and Hartree-Fock approximations to many-electron atoms.

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EPJ A Highlight - Emergence of nuclear rotation from elementary interactions between the nucleons

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Rotational bands in an ab initio calculations for the nuclear excitation spectrum of 11Be.

Nuclei are quantum many-body systems which exhibit emergent degrees of freedom, from shell structure and clustering to collective rotations and vibrations. Such emergent phenomena are traditionally the domain of phenomenological models, yet their description can now be placed on a more fundamental footing in terms of microscopic theory. The nature and emergence of rotational bands are presently investigated in light nuclei through ab initio nuclear many-body calculations. Beyond simply analyzing spectroscopic signatures, the structural insight are investigated in terms of angular momentum coupling schemes and group theoretical correlations as underpinnings for the rotational structure.

EPJ D Highlight - Slowing light in an optical cavity with mechanical resonators and mirrors

A schematic diagram of the position-dependent mass optomechanical system studied in this work.

Theoretical physicists Kamran Ullah and Hameed Ullah have shown how a position-dependent mass optomechanical system involving a cavity between two mirrors, one attached to a resonator, can enhance induced transparency and reduce the speed of light.

We are all taught at high school that the speed of light through a vacuum is about 300000 km/s, which means that a beam from Earth takes about 2.5 seconds to reach the Moon. It naturally moves more slowly through transparent objects, however, and scientists have found ways to slow it dramatically. Optomechanics, or the interaction of electromagnetic radiation with mechanical systems, is a relatively new and effective way of approaching this. Theoretical physicists Kamran Ullah from Quaid-i-Azam University, Islamabad, Pakistan and Hameed Ullah from the Institute of Physics, Porto Alegre, Brazil have now demonstrated how light is slowed in a position-based mass optomechanical system. This work has been published in EPJ D.

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EPJ D Topical review - Crystal-based intensive gamma-ray light sources

In a Topical review just published in EPJD, A.V. Korol and A.V. Solov'yov (MBN Research Center, Germany) discuss possibilities for designing and practical realization of novel intensive gamma-ray Crystal-based LSs (CLS) operating at photon energies from 102 keV and above that can be constructed exposing oriented crystals to beams of ultrarelativistic particles. CLSs can generate radiation in the photon energy range where the technologies based on the fields of permanent magnets become inefficient or incapable.

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Roberta Caruso joins the EPJ Scientific Advisory Committee (SAC)

Roberta Caruso

The Scientific Advisory Committee of EPJ is delighted to welcome Dr Roberta Caruso as the new representative for the European Physical Society.

Roberta Caruso is a post-doctoral researcher at University of Naples, where she works in the field of hybrid superconducting devices and oxide interfaces. She has been an EPS member since 2010, where she worked for many years within the committee of the Young Minds project.

Editor-in-Chief
K. Bongs
ISSN: 2196-0763 (Electronic Edition)

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