- Published on 27 July 2015
Physicists now better understand wave systems exhibiting unusual disturbances by identifying growing localised patterns as early indicators of such disturbances
Physicists like to study unusual kinds of waves, like freak waves found in the sea. Such wave movements can be studied using models designed to describe the dynamics of disturbances. Theoretical physicists, based in France have focused on finding ways of best explaining how wave disturbance occurs under very specific initial conditions that are key to the genesis of these disturbances. They looked for solutions to this puzzle by resolving a type of equation, called the nonlinear Schrödinger equation. It is solved by applying a method designed for studying instabilities tailored to these initial conditions. Their approach makes it possible to locate exactly where and how pertinent information used to identify disturbance patterns can be extracted from localised disturbances' characteristics. The findings have been published in EPJ D by Saliya Coulibaly, from the University of Lille, and colleagues.
- Published on 22 July 2015
How many different measurement settings are needed in order to uniquely determine a pure quantum state, and how should such measurements be chosen? This problem goes back to a famous remark by Wolfgang Pauli in 1933, in which he raised the question whether or not the position and the momentum distributions are enough to define the wave function uniquely modulo a global phase. The original Pauli problem has a negative answer, but it has evolved into many interesting variants and has been studied from several fruitful perspectives.
In this review article the authors concentrate on a specific form of the Pauli problem, which is concerned with the minimal number of orthonormal bases in a finite dimensional Hilbert space that is needed in order to distinguish all pure quantum states.
- Published on 29 June 2015
Hyperfine structure of light absorption by short-lived cadmium atom isotopes reveals characteristics of the nucleus that matter for high precision detection methods
Atoms absorb and emit light of various wavelengths. Physicists have long known that there are some tiny changes, or shifts, in the light that gets absorbed or emitted, due to the properties of the atomic nucleus. Now, a team of scientists has elucidated the so-called hyperfine structure of cadmium atoms. Relying on a method called laser spectroscopy, they have measured variations in the energy transition within cadmium atom - Cd in the periodic table. They studied a chain of isotopes with an odd number of neutrons ranging from 59 in 107Cd to 75 in 123Cd. From these high-precision measurements, they were able to identify the physical cause of the shift within the nucleus. These findings by Nadja Frömmgen from the Johannes Gutenberg University Mainz, in Germany, and international colleagues have now been published in EPJ D.
EPJ D Colloquium - Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions
- Published on 18 June 2015
A new Colloquium paper published in EPJ D describes recent advances in the use of the Schwinger multichannel method and considers potential future applications of the technique. Based on the Schwinger variational principle for the scattering amplitude, the Schwinger multichannel method was designed to account for exchange, polarization and electronically multichannel coupling effects in the low-energy region of electron scattering from molecules with arbitrary geometry.
- Published on 13 May 2015
Carbon-based nanoparticles could be used to sensitize cancerous tumours to proton radiotherapy and induce more focused destruction of cancer cells, a new study shows
Radiotherapy used in cancer treatment is a promising treatment method, albeit rather indiscriminate. Indeed, it affects neighbouring healthy tissues and tumours alike. Researchers have thus been exploring the possibilities of using various radio-sensitizers; these nanoscale entities focus the destructive effects of radiotherapy more specifically on tumour cells. In a study published in EPJ D, physicists have now shown that the production of low-energy electrons by radio-sensitizers made of carbon nanostructures hinges on a key physical mechanism referred to as plasmons—collective excitations of so-called valence electrons; a phenomenon already documented in rare metal sensitizers. This reseach was conducted by Alexey Verkhovtsev, affiliated with the MBN Research Center in Frankfurt, Germany and A.F. Ioffe Physical-Technical Institute in St Petersburg, Russia and an international team.
- Published on 15 April 2015
Physicists have now devised an elegant plasma pressure diagnostic method by studying forces akin to the pressure change at the inner walls of energy saving light bulb when the light is switched on
Could the mundane action of switching on an energy saving light bulb still hold secrets? It does, at least for physicists. These bulbs are interesting because they contain low-temperature plasma—a gas containing charges from ions and electrons. Now, a German team has developed a method that could be used for measuring the increase in the plasma force on the inner side of such a light bulb when the light is switched on. These findings from Thomas Trottenberg and colleagues from Christian-Albrechts University in Kiel, Germany, have just been published in EPJ D. They have implications for plasma diagnostics concerning plasma-wall interactions used in surface modification and the production of thin film solar cells and microchips.
- Published on 17 March 2015
Data on the transport of electrical charges in water vapour provide the key ingredients to new plasma models applicable to medicine
Applications of plasmas in medicine are a new frontier in therapeutic treatment. For example, they can help in stimulating tissue regeneration in the contexts of wound healing and dermatology. Before these and further applications can be developed, it is essential to understand the processes at work in plasmas - a unique kind of gas-like state of matter containing charged particles. Now a study published in EPJ D by a team led by Zoran Petrović from the University of Belgrade, Serbia, provides previously unavailable data on oxygen ion transport and the likelihood of such ions interacting with water molecules. These could contribute to new models of plasmas in liquids which account for how discharges are created in water vapour.
- Published on 11 February 2015
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.
- Published on 10 February 2015
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.
- Published on 28 January 2015
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.