2016 Impact factor 1.862
Special Topics

EPJ E Highlight - Unexpected undulations in biological membranes

Schematic illustration of the fluctuating membrane in a structured fluid.

Study of the dynamic properties of biological membranes reveals new anomalous behaviour under specific circumstances

How biological membranes - such as the plasma membrane of animal cells or the inner membrane of bacteria - fluctuate over time is not easy to understand, partly because at the sub-cellular scale, temperature-related agitation makes the membranes fluctuate constantly; and partly because they are in contact with complex media, such as the cells’ structuring element, the cytoskeleton, or the extra-cellular matrix. Previous experimental work described the dynamics of artificial, self-assembled polymer-membrane complexes, embedded in structured fluids. For the first time, Rony Granek from Ben-Gurion University of The Negev, and Haim Diamant from Tel Aviv University, both in Israel, propose a new theory elucidating the dynamics of such membranes when they are embedded in polymer networks. In a new study published in EPJ E, the authors demonstrate that the dynamics of membrane undulations inside such a structured medium are governed by distinctive, anomalous power laws.

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EPJ Plus Highlight - How small does your rice pudding need to get when stirring jam into it?

Gibbs (full lines) and Boltzmann (dashed lines) free energies.

New study shows that two seemingly diverging theories of ever-increasing disorder, known as entropy, can be tested against each other experimentally in the smallest possible systems

Have you ever tried turning the spoon back after stirring jam into a rice pudding? It never brings the jam back into the spoon. This ever-increasing disorder is linked to a notion called entropy. Entropy is of interest to physicists studying the evolution of systems made up of multiple identical elements, like gas. Yet, how the states in such systems should be counted is a bone of contention. The traditional view developed by one of the fathers of statistical mechanics, Ludwig Boltzmann - who worked on a very large number of elements - is opposed to the seemingly disjointed theoretical perspective of another founding scientists of the discipline, Willard Gibbs, who describes systems with a very small number of elements. In a new study published in EPJ Plus, Loris Ferrari from the University of Bologna, Italy, demystifies this clash between theories by analysing the practical consequences of Gibbs’ definition in two systems of a well-defined size. Ferrari speculates about the possibility that, for certain quantities, the differences resulting from Boltzmann's and Gibbs' approach can be measured experimentally.

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EPJ D Highlight - Quantum noise reduction method for enhanced precision in atomic clocks

Atomic clock. Credit: Wendy via Flickr (CC BY-SA 2.0).

Atomic Spin Squeezing: not the Olympic sport of your dreams, but a way of enhancing measurement reliability at the quantum scale

Noise: it affects us all by distracting us. Noise also occurs at the quantum scale and can e.g. interfere with the measurements of atomic fountain clocks or with quantum information processing. This is because at that scale, there are effects that don't exist at larger scales. As such, finding ways to reduce quantum noise can enhance the precision of measurement in the examples given above. Now a team of physicists including Aranya Bhattacherjee from Jawaharlal Nehru University, New Delhi, India and colleagues are investigating ways of improving the analysis of quantum noise measurement in the case of spectroscopic investigations; their preliminary findings were released in a study in EPJ D. This method, called atomic spin squeezing, works by redistributing the uncertainty unevenly between two components of spin in these measurements systems, which operate at the quantum scale. The spin represents a degree of freedom of the quantum particles involved. Thus, the spin component with reduced uncertainty becomes more precise in delivering its measurement - as the two are inversely correlated. Potential applications include the development of future quantum networks.

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Managing Editors
Agnès Henri (EDP Sciences) and Sabine Lehr (Springer-Verlag)
Dear Sabine,
On this occasion, may I also thank you for your support: collaboration with you is always very pleasant and effective. Have a nice day, yours, Yurij

Yurij Holovatch, National Academy of Sciences, Lviv, Ukraine
Editor EPJ Special Topics 216, 2013

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

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