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EPJ Plus Highlight - An efficient Lattice-Boltzmann approach for studying compressible flow in nonlinear thermoacoustic engines

Contours of the Mach number near the stack at phase π under the limit cycle.

Thermoacoustics is the physics of the interaction of thermal and acoustic fields. The nonlinear acoustic effect and low Mach number compressible flow in thermoacoustic engines make the theoretical analysis of such systems extremely complicated. A new study investigates the nonlinear self-excited thermoacoustic onset in a Rijke tube via the lattice Boltzmann method (LBM), which simulates the fluid flow by tracking the evolution of particles and obtains flow stream and heat transfer patterns from the kinetic level. The adopted LBM model, which was developed by the authors, convincingly simulates the Navier-Stokes-Fourier equations, treating accurately the nonlinear process of wave excitation of coupled fields and providing reliable estimates for pressure, density, velocity and temperature in such a finite geometry.

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EPJB Colloquium - How to understand real-world complexity through multiplex networks

An illustrative example of the multiplex network of nine nodes with two layers, the red solid) and the blue (dashed) layer.

Many real-world complex systems (from living organisms to human societies to transportation system) are best modeled by multiplex networks of interacting network layers. The study of multiplex network is one of the newest and hottest themes in the statistical physics of complex networks. Compared to single networks the current level of our understanding of multiplex networks is far from satisfactory. Pioneering studies have proven that the multiplexity has broad impact on the system's structure and function. Novel phenomena, unforeseen in traditional single-layer framework, can arise as a consequence of the coupling of network layers. In this EPJ B Colloquium Kyu-Min Lee, Byungjoon Min, and Kwang-Il Goh organize and review of the growing body of literature on statistical physics of multiplex networks by categorizing existing studies broadly according to the type of layer coupling in the problem. They discuss the recent major developments and point out some outstanding open challenges and research questions that warrant serious investigation, such as the identification of the minimal couplings (in the renormalization group sense) relevant to the characteristic discontinuous transitions in multiplex systems.

EPJ E Highlight - How do vertebrates take on their form?

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Modeling of the fold formation mechanism. A sheet of rubber on which a (stiffer) paper label is stuck buckles along the boundary between the stiff zone and the soft zone when it is stretched. This reproduces the formation of folds along the boundaries between cellular domains. © VF-CNRS-MSC/EDP Sciences-SIF-Springer SBM

A simple physical mechanism that can be assimilated to folding, or buckling, means that an unformed mass of cells can change in a single step into an embryo organized as a typical vertebrate. This is the main conclusion of work by a team involving physicists from the Laboratoire Matière et Systèmes Complexes (CNRS/Université Paris Diderot) and a biologist from the Laboratoire de Biologie du Développement (CNRS/UPMC).

Thanks to microscopic observations and micromechanical experiments, the scientists have discovered that the pattern that guides this folding is present from the early stages of development. The folds that will give a final shape to the animal form along the boundaries between cell territories with different properties. This work has shed light on the mechanism for the formation of vertebrates and thus how they appeared during evolution. These findings have just been published in EPJ E.

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EPJ D Highlight - Novel high-power microwave generator

Axial profile of the axisymmetric semi-circular structure to be used as a slow wave structure in backward wave oscillators.

A new study explores the viability of a novel structure to be used as a component of a high-power microwave source, designed to transfer energy to targets via ultra-high-frequency radio waves

High-power microwaves are frequently used in civil applications, such as radar and communication systems, heating and current drive of plasmas in fusion devices, and acceleration in high-energy linear colliders. They can also be used for military purpose in directed-energy weapons or missile guidance systems. In a new study published in EPJ D, scientists from Bangladesh demonstrate that their proposed novel method, which is capable of producing such microwaves, offers a viable alternative to traditional approaches. The solution was developed by Md. Ghulam Saber and colleagues from the Islamic University of Technology in Gazipur, Bangladesh.

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EPJ D – Graphical abstracts now required in EPJ D

We are pleased to inform the readers and authors of EPJ D that from now on articles published in the journal will feature a graphical abstract. While it is not meant to provide specific results, this element will serve the purpose of conveying visually the gist of the article, along with the title. Authors may use an item already present in the manuscript or a purpose-made graphic. The use of color is strongly encouraged. Images previously published under the copyright of other publishers cannot be considered.

EPJ A Highlight - Mechanisms of two-proton emission seen in three-body correlations

Sequential two-proton decay of the 16Ne Er=7.57 MeV state. The fractional energy distribution (left) gives resonance energy in 15F while the angular distribution (right) determines Iπ of the initial state.

Hitherto three-body correlations between decay products of nuclear resonances, unstable to the emission of two neutrons have been a very effective tool in the analysis of GSI-experiments on 5H, 10He, 13Li, and 14Be. Here the first report is given about the mechanisms for two-proton emission from states in 16Ne, representing the presently most complete study of this nucleus. One-neutron knockout from 17Ne populated the 16Ne(g.s.) (Er=1.39 MeV, Γ=0.08 MeV) above the 14O+p+p threshold, and resonances at Er=3.22 MeV and 7.57 MeV. The decay mechanisms were revealed analysing three-body energy correlations in the 14O+p+p system. It was found that the 16Ne(g.s.) undergoes a democratic three-body decay. In contrast to this, the 16Ne(21+) state emits protons through the 15F(g.s.) sequentially. The decay of 7.57 MeV state is well-described assuming emission of a proton from the d5/2 shell to 15F(5/2+), which decays by d5/2 proton emission to 14O(g.s.). By using R-matrix analysis and mirror symmetry this state was unambiguously identified as the third 2+ state in 16Ne.

EPJ Plus Highlight - Ultrafast laser for crafting ever thinner solar cells

Interaction between ultrashort pulse laser and a target.

Solar-cell efficiency depends on how thin it can be manufactured. Now, a new model exploits femtosecond laser sources to get higher efficiency at lower cost

The race for ever more efficient and cheaper solar cells tests the limits of manufacturing. To achieve this, photovoltaic solar cells need to become thinner and are made of more complex inner structures. Now, Italian scientists have investigated and expanded a model elucidating the dominant physical processes when ultra-fast lasers are used in manufacturing solar cells to these specifications. An article by Alberto Gurizzan and Paolo Villoresi from the University of Padova in Italy detailing this model has now been published in EPJ Plus.

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EPJ ST Highlight - Analogue quantum computers: still wishful thinking?

Many challenges lie ahead before quantum annealing, the analogue version of quantum computation, contributes to solve combinatorial optimisation problems

Traditional computational tools are simply not powerful enough to solve some complex optimisation problems, like, for example, protein folding. Quantum annealing, a potentially successful implementation of analogue quantum computing, would bring about an ultra-performant computational method. A series of reviews in this topical issue of EPJ ST, guest-edited by Sei Suzuki from Saitama Medical University, Japan, and Arnab Das from the Indian Association for the Cultivation of Science, Kolkota, India, focuses on the state of the art and challenges in quantum annealing. This approach, if proven viable, could greatly boost the capabilities of large-scale simulations and revolutionise several research fields, from biology to economics, medicine and material science.

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EPJ B Highlight - Probing qualities at the tips of nanocones

3D graphs of the local density of states with and without spin–orbital interaction for different distances r from the tip.

New understanding of electron behaviour at the tips of carbon nanocones could help provide candidates for use as a novel probe in atomic force microscopy

One of the ways of improving electrons manipulation is though better control over one of their inner characteristics, called spin. This approach is the object of an entire field of study, known as spintronics. Now, Richard Pincak from the Slovak Academy of Sciences and colleagues have just uncovered new possibilities for manipulating the electrons on the tips of graphitic nanocones. Indeed, in a study published in EPJ B, they have shown that because the tip area offers the greatest curvature, it gives rise, in the presence of defects, to an enhanced manifestation of a phenomenon called spin-orbit interaction. This, in turn, affects its electronic characteristics. These nanocones could thus become candidates for a new type of scanning probe in atomic force microscopy.

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EPJ D Highlight - The power of light-matter coupling

Illustration of molecules coupled to the fundamental optical mode of a 145nm thick Fabry-Perot cavity. It features a typical example of the absorption spectrum of uncoupled (red line) and coupled (dark line) molecules. © A. Canaguier-Durand et al.

A theoretical study shows that strong ties between light and organic matter at the nanoscale open the door to modifying these coupled systems’ optical, electronic or chemical properties.

Light and matter can be so strongly linked that their characteristics become indistinguishable. These light-matter couplings are referred to as polaritons. Their energy oscillates continuously between both systems, giving rise to attractive new physical phenomena. Now, scientists in France have explained why such polaritons can remain for an unusual long time at the lowest energy levels, in such a way that alters the microscopic and macroscopic characteristics of their constituting matter. These findings thus pave the way for optical, electronic and chemical applications. The work has been published in EPJ D by Antoine Canaguier-Durand from the University of Strasbourg, France, and colleagues.

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Editors-in-Chief
L. Baudis, G. Dissertori, K. Skenderis and D. Zeppenfeld

Deputy Editors-in-Chief
D. J. Schwarz

I am very grateful for the great professionality and efforts that all the staff of the EJPC makes in order to attend all the necessities of the authors.

Diego Julio Cirilo-Lombardo

ISSN: 1434-6044 (Print Edition)
ISSN: 1434-6052 (Electronic Edition)

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