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EPJ E Highlight - Thermodiffusion in weightlessness

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Flow pattern 2 min after the start of vibrations. © Y. Gaponenko et al.

Zero gravity experiments on the International Space Station shed some light on thermodiffusion effects, relevant to the oil and gas industry and global warming prevention processes

Thermodiffusion, also called the Soret effect, is a mechanism by which an imposed temperature difference establishes a concentration difference within a mixture. Two studies by Belgian scientists from the Free University of Brussels, recently published in EPJ E, provide a better understanding of such effects. They build on recent experimental results from the IVIDIL—Influence Vibration on Diffusion in Liquids—research project performed on the International Space Station under microgravity to avoid motion in the liquids.

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EPJ D Highlight - Quantum holograms as atomic scale memory keepsake

Set up of the experiment showing the orthogonal side illumination. © A. N. Vetlugin et al.

A new theoretical study demonstrates for the first time that quantum holograms could be a candidate for becoming quantum information memory

Russian scientists have developed a theoretical model of quantum memory for light, adapting the concept of a hologram to a quantum system. These findings are included in study just published in EPJ D, by Anton Vetlugin and Ivan Sokolov from St. Petersburg State University in Russia. The authors demonstrate for the first time, that it is theoretically possible to retrieve, on demand, a given portion of the stored quantised light signal of a holographic image—set in a given direction in a given position in time sequence.

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EPJ D Colloquium: Recent positron-atom cross section measurements and calculations

In this EPJ D colloquium paper, the authors review a cross-section of recent results relating to low-energy positron scattering from atomic targets, and present a comparison of the latest measurements and calculations for positron collisions with the noble gases, together with a brief update on the newest studies addressing other atomic targets. In particular, they provide an overview of the work that has been done in examining elastic scattering, positronium formation, direct and total ionisation, as well as total scattering, at typical energies ranging from 0.1 eV to a few hundred eV.

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EPJ Plus Highlight - Electric/magnetic dipole in an electromagnetic field: force, torque and energy

How does an electric (or magnetic) dipole behave in an electromagnetic field, when its velocity becomes comparable with the speed of light?

This problem has been solved for the first time in a paper recently published in EPJ Plus, where novel relativistic effects were found. In particular, it has been shown that the concept of “hidden” momentum of magnetic dipoles in an electric field, being disputable up to date, is strongly required to derive relativistically adequate solutions. Moreover, a novel concept of “latent” momentum of electric dipole should be also involved into the description of dipoles.

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EPJ B video: Three Reasons to Publish in EPJB

Watch a two-minute video in which Professor Luciano Colombo, Colloquium Editor at EPJ B, explains the benefits of choosing to publish in this journal.

EPJ Plus Highlight - Balancing renewable energy costs

Two weeks taken from the 2011 chronicle of the time dependence of the power demand in the French metropolitan territory. © Bonin et al.

Simulating the cost of generating a combination of electricity sources while accounting for the fluctuating nature of energy production and demand provides tools to optimise such energy mix

Increasing reliance on renewable energies is the way to achieve greater CO2 emission sustainability and energy independence. Yet, because such energies are only available intermittently and energy cannot be stored easily, most countries aim to combine several energy sources. Now, in a new study in EPJ Plus, French scientists have come up with an open source simulation method to calculate the actual cost of relying on a combination of electricity sources. Bernard Bonin from the Atomic Energy Research Centre CEA Saclay, France, and colleagues demonstrate that cost is not directly proportional to the demand level. Although recognised as crude by its creator, this method can be tailored to account for the public’s interest—and not solely economic performance—when optimising the energy mix.

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EPJ D Highlight - Atmospheric chemistry hinges on better physics model

Representations of a component of the wave packet of the N2O molecule during photoabsorption. © M. N. Daud

Improved theoretical model of photoabsorption of nitrous oxide matters because its by-product, nitric oxide, is involved in the catalytic destruction of stratospheric ozone

New theoretical physics models could help us better grasp the atmospheric chemistry of ozone depletion. Indeed, understanding photoabsorption of nitrous oxide (N2O)-- a process which involves the transfer of the energy of a photo to the molecule--matters because a small fraction of N2O reacts with oxygen atoms in the stratosphere to produce, among other things, nitric oxide (NO). The latter participates to the catalytic destruction of ozone (O3). Now, new theoretical work unveils the actual dynamic of the photoabsorption of nitrous oxide (N2O) molecules. These findings by Mohammad Noh Daud from the University of Malaya, Kuala Lumpur in Malaysia, have just been published in EPJ D. The work has led to new calculations of the probability of an absorption process taking place, also referred to as absorption cross section, which confirm experimental results.

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EPJ D Topical Review - Applied Bohmian Mechanics

Interaction of a hydrogen atom with a left-circularly polarized Laguerre-Gaussian beam

Bohmian mechanics provides an explanation of quantum phenomena in terms of point particles guided by wave functions. This EPJ D review focuses on the formalism of non-relativistic Bohmian mechanics, rather than its interpretation, and although the Bohmian and standard quantum mechanical theories have different formalisms, they both yield exactly the same predictions for all phenomena.

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EPJ D Topical Review - The density matrix renormalization group for ab initio quantum chemistry

Over the past 15 years, the density matrix renormalisation group (DMRG) has become increasingly important for ab initio quantum chemistry. Its underlying wavefunction ansatz, the matrix product state (MPS), is a low-rank decomposition of the full configuration interaction tensor. The virtual dimension of the MPS, viz. the rank of the decomposition, controls the size of the corner of the many-body Hilbert space that can be reached with the ansatz, and can be systematically increased until numerical convergence is reached. The MPS ansatz naturally captures exponentially decaying correlation functions, and the DMRG therefore works extremely well for noncritical one-dimensional systems.

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EPJ B Highlight - Taking advantage of graphene defects

The scattering potential in real space calculated based on the Fourier image. © S. Koniakhin

New theoretical model of the effect of triangular defects in graphene provides numerical estimates of the resulting current rectification with potential applications in security screening.

Electronic transport in graphene contributes to its characteristics. Now, a Russian scientist is proposing a new theoretical approach to describe graphene with defects—in the form of artificial triangular holes—resulting in the rectification of the electric current within the material. Specifically, the study provides an analytical and numerical theory of the so-called ratchet effect —which results in a direct current under the action of an oscillating electric field, due to the skew scattering of electronic carriers by coherently oriented defects in the material. These findings are published in EPJ B by Sergei Koniakhin from the Ioffe Physical-Technical Institute and the Academic University - Nanotechnology Research and Education Centre, both affiliated with the Russian Academy of Sciences in St. Petersburg.

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Editors-in-Chief
G. Dissertori, J. Monroe, K. Skenderis and D. Zeppenfeld

Deputy Editors-in-Chief
D. J. Schwarz

We especially appreciate the reviewer's patience and many helpful suggestions.

Zhang-Yu Nie

ISSN: 1434-6052 (Electronic Edition)

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Springer-Verlag