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EPJ ST Highlight - Tiny animal hairs could act as sensitive compass needles

Stereocilia bundles in the inner ear.

Statistical mechanics shows that some animals may be able to perceive Earth’s magnetic field with bundles of microscopic hairs in their inner ears.

The exact mechanisms animals use to sense the direction of Earth’s magnetic field have long remained a mystery. One leading theory suggests that this ability is tied to bundles of microscopic hair cells in the inner ears. Through new research published in EPJ ST, Kirill Kavokin at St Petersburg State University, Russia, uses statistical analysis to show that just around 100 of these hair cells could act as effective biological compass needles, allowing animals to accurately sense the magnetic field surrounding them.

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EPJ Plus Highlight - Modelling the use of Beta Radiation in cancer treatment

An illustration of beta decay proceeding against the backdrop of a Monte Carlo simulation. Credit: Robert Lea

New research pits the simulation of beta radiation doses in tumour treatment against an analytical method.

Treating superficial skin tumours especially when they are located above cartilage or bone with beta radiation can help protect sensitive structures during the delivery of treatment.

The use of short-range beta radiation in cancer treatment is not without its disadvantages, however, especially when it comes to the measurement of radiation exposure — dosimetry. When experimental dosimetry is not feasible, researchers use simulations and calculations to study the interaction of the ionizing radiation with matter and estimate the radiation dose delivered to a target organ.

A new paper published in EPJ Plus and authored by Eduardo De Paiva, from the Division of Medical Physics at the Institute of Radiation Protection and Dosimetry, Rio de Janeiro, Brazil, and his colleagues, pits the gold standard of simulation techniques — Monte Carlo (MC) simulation — against an alternative analytic method, the Loevinger formula.

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EPJ E Colloquium - Thermophoresis and thermal orientation of Janus nanoparticles in thermal fields

Thermal gradients induce thermodiffusion in aqueous solutions and liquid mixtures and thermophoretic forces that drive the motion of colloids towards hot or cold regions. The Soret coefficient quantifies the strength of the thermophoretic force and varies with temperature, colloid mass and diameter, and colloid-solvent interactions. Janus colloids (JCs ) are nanoparticles with heterogeneous compositions and two contrasting properties, or "two faces" like the Roman god Janus. For example, in spherical JCs, one hemisphere might be hydrophilic and the other hydrophobic. The interest in JCs has grown steadily given their applicability in materials science. While the behaviour of JCs under equilibrium conditions has been explored, their response to thermal gradients is still not fully understood. Explaining the behaviour of JCs in a thermal field might expand their use in materials science and biomedical applications.

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EPJ D Colloquium - Overview of photo-neutralization techniques for negative ion-based neutral beam injectors in future fusion reactors

The need for safe, carbon-free and abundant sources of energy is becoming more and more pressing. While still under development, nuclear fusion can play a key role in a medium term, decarbonized energy scenario. However, in order for fusion to be commercially competitive, many sub-systems constituting the current experimental reactors need to be optimized in terms of their efficiency: in particular, DEMO and future fusion energy plants will require a substantial increase in the energy performances of the plasma heating systems.

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EPJ E Highlight - Considering how friction is maximised when liquids flow on nanoscales

A cross-section of simulations of several different flow types with pistons placed at different positions. Credit: S. Chen et al, 2022

By simulating a liquid confined by a nanoscale structure, researchers discovered the role molecular clogging plays in friction.

The dynamics of how liquids behave when confined in a nanoscale-sized space such as nanochannels, nanotubes or nanopores, is key to understanding a wealth of processes including lubrication, filtration and even energy storage.

The dynamics of liquids at nanoscales are different to behaviour in confinement at macroscales, however. One of the key differences that a reduction in scale creates is friction and shear between the liquid and its solid container. And further complications arise in systems with solid-to-solid contact with features like wear, micro-pitting and scuffing created.

A new paper published in EPJ E and authored by Shan Chen, from the State Key Laboratory of Organic-Inorganic Composites at Beijing University of Chemical Technology, China, uses simulations of molecular dynamics to look at the friction-induced nano-confined liquids.

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EPJ B Highlight - Assessing the effect of hydraulic fracturing on microearthquakes

A cross-section of a hydrofracturing site showing preconditioning by blasting. Credit: de la Barra. E., et al, [2022]

New research examines mining sites with hydraulic fracturing comparing it to those without to determine the practice’s effect on seismic hazards.

The analysis of low-intensity human-caused microearthquakes, including their magnitude and frequency, has become an important factor in mining. This is a consideration not only for the safety of mining staff, but also for extraction rates and mine stability that can have major impacts on business performance. Increasingly, the practice of hydraulic fracturing is used to precondition mines and diminish the magnitude of induced tremors as well as reduce the number of rock fragments extracted.

A new paper published in EPJ B assesses the impact of hydraulic fracturing on seismic hazards like microearthquakes, an important issue for the safety of workers and the continuation of mining operations. The paper is authored by Erick de la Barra, Pedro Vega-Jorquera and Héctor Torres from the University of La Serena, Chile, alongside Sérgio Luiz E. F. da Silva from Politecnico di Torino, Department of Applied Science and Technology, Turin, Italy.

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EPJ H Highlight - A step towards quantum gravity

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Representation of the Earth affecting the curvature of spacetime. https://commons.wikimedia.org/wiki/ File:Spacetime_lattice_analogy.svg Mysid, CC BY-SA 3.0.

Resolving the problem of time

In Einstein’s theory of general relativity, gravity arises when a massive object distorts the fabric of spacetime the way a ball sinks into a piece of stretched cloth. Solving Einstein’s equations by using quantities that apply across all space and time coordinates could enable physicists to eventually find their ‘white whale’: a quantum theory of gravity. In a new article in EPJ H: Historical Perspectives on Contemporary Physics, Donald Salisbury from Austin College in Sherman, USA, explains how Peter Bergmann and Arthur Komar first proposed a way to get one step closer to this goal by using Hamilton-Jacobi techniques. These arose in the study of particle motion in order to obtain the complete set of solutions from a single function of particle position and constants of the motion.

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Luís Carlos joins the EPJ Scientific Advisory Committee (SAC)

Luís Carlos

The Scientific Advisory Committee of EPJ is delighted to welcome Prof. Luís Carlos as the new representative for the Portuguese Physical Society.

Luís D. Carlos is a full professor at the University of Aveiro, Portugal, where he works in the field of optical materials, luminescence nanothermometry and applications of organic-inorganic hybrids in luminescent solar concentrators, solid-state lighting, and integrated optics

EPJ QT Highlight - Quantum control for advanced technology: Past and present

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A new review lays out a roadmap for quantum technologies. Credit: Robert Lea

Quantum devices are a promising technological advance for the future, but this will hinge on the application of quantum optimal control top real-world devices. A new review looks at the status of the field as it stands.

One of the cornerstones of the implementation of quantum technology is the creation and manipulation of the shape of external fields that can optimise the performance of quantum devices. Known as quantum optimal control, this set of methods comprises a field that has rapidly evolved and expanded over recent years.

A new review paper published in EPJ Quantum Technology and authored by Christiane P. Koch, Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin along with colleagues from across Europe assesses recent progress in the understanding of the controllability of quantum systems as well as the application of quantum control to quantum technologies. As such, it lays out a potential roadmap for future technology.

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EPJ TI Highlight - QEMMS: Improving measurements of the kilogram

The QEMMS mechanism

Currently in development by NIST, QEMMS will allow researchers to measure macroscopic masses, based on quantum principles. New analysis shows how an optimised design of this device could significantly reduce the errors associated with current approaches to mass measurement.

Until 2018, the SI unit of mass, the kilogram, was defined as the mass of a real object: the International Prototype Kilogram, kept in a secure facility in the outskirts of Paris. On November 16, 2018, the kilogram was given a new, internationally-accepted definition, based on three defining constants: the speed of light, the Planck constant, and the hyperfine transition frequency of caesium. One of the methods to measure a mass based on the new definition is a device named the Kibble balance.

Despite the current precision of this device’s measurements, its components can be improved to reduce sources of uncertainties. Through new research published in EPJ Techniques and Instrumentation, Darine Haddad and colleagues at the National Institute of Standards and Technology (NIST) show how a new, optimised approach to the Kibble balance’s design could further improve its accuracy.

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Managing Editors
Anne Ruimy and Vijala Kiruvanayagam (EDP Sciences) and Sabine Lehr (Springer-Verlag)
Dear Sabine and Isabelle,
Thank you so much for all your help and excellent work you did on the EPJ ST volume "Nonlinear Dynamics of Deterministic and Stochastic Systems: Unraveling Complexity". This was a great experience and collaboration.

Alexander Neiman (on behalf of the guest editors), Ohio University, Athens, USA
Editor EPJ Special Topics 222/10, 2013

ISSN: 1951-6355 (Print Edition)
ISSN: 1951-6401 (Electronic Edition)

© EDP Sciences and Springer-Verlag