News / Highlights / Colloquia
- Published on 30 July 2015
A new study reveals how hexagonal-patterned, self-organised hill structures emerge in 2D at the nanoscale due to redeposition following semi-conductor bombardment with low-energy ions
Nanoscale worlds sometimes resemble macroscale roller-coaster style hills, placed at the tip of a series of hexagons. Surprisingly, these nanohills stem from the self-organisation of particles – the very particles that have been eroded and subsequently redeposited following the bombardment of semi-conductors with ion beams. Now, a new theoretical study constitutes the first exhaustive investigation of the redeposition effect on the evolution of the roughening and smoothing of two-dimensional surfaces bombarded by multiple ions. The results demonstrate that the redeposition can indeed act as stabilising factor during the creation of the hexagonally arranged dot patterns observed in experiments. These findings by Christian Diddens from the Eindhoven University of Technology, in the Netherlands, and Stefan Linz, from Munster University, Germany, have been published in a study published in EPJ B.
- Published on 07 July 2015
Study finds the law governing how heat transport scales up with temperature
How heat travels, matters. Yet, there is still no consensus on the exact physical mechanism that causes anomalous heat conduction - despite the existence of previous numerical simulation, theoretical predictions and experimental observations. Now, a team based in Asia has demonstrated that electron transport depends on temperature. It follows a scaling governed by a power law - and not the exponential scaling previously envisaged. These findings were recently published in EPJ B by Yunyun Li Tongji University, Shanghai, China, and colleagues in Singapore.>
- Published on 30 June 2015
Iron-Nickel alloys’ structure changes as they heat up and cool down
Iron-nickel alloys are ubiquitous: they are found at the earth’s core and in meteorites. What is fascinating about such alloys is that their inner structure can change with rapid temperature swings. Heated up above 730 °C (1,340 °F), these alloys enter what is referred to as an austenitic phase. Alternatively, they can be turned into very hard alloys, referred to as a martensitic phase, by subjecting them to extremely rapid cooling. Now a team of scientists from Germany has, for the first time, created a large-scale simulation involving 275,000 atoms representing iron-nickel alloys in proportions found in nature. They show that transitions from one alloy structure to the other occurs in both an orderly and a disorderly way, depending on whether it is heated up or cooled down, respectively. These findings have been published in EPJ B by Emilia Sak-Saracino and Herbert Urbassek from the Research Center OPTIMAS at the University of Kaiserslautern, in Germany.
- Published on 24 June 2015
'Big Data' from electronic records derived from mobile telephone calls enables the study human behaviour and sociality in a quantitative way and with unprecedented statistical power. Cell phones are ubiquitous and Call Detail Records (CDRs), automatically collected by telecom operators are records of verified, time-stamped one-to-one communication. They are particularly useful to understand one-to-one communication patterns, as well as the dynamics of the social networks that are reflected in such patterns. In this EPJ B Colloquium, Jari Saramäki and Esteban Moro present an overview of empirical results pertaining to the multi-scale nature of social dynamics and networks, as inferred from CDRs.
- Published on 15 June 2015
Graphics Processing Units (GPU) are currently used as a cost-effective platform for computer simulations and big-data processing. Large scale applications require that multiple GPUs work together, but the efficiency obtained with cluster of GPUs is, at times, suboptimal because the GPU features are not exploited at their best.
- Published on 26 May 2015
Analytical techniques, originally developed for traditional materials, turn out to be very useful to study the composition and structure of artistic and historical specimens. But the reverse is also true. The study of ancient artefacts is providing interesting insights of more general interest to materials scientists, as well as inspiration for current artists.
- Published on 19 May 2015
Networks of networks, or multilayer networks, are a fitting description of social systems. Small and seemingly irrelevant changes in a network can have catastrophic consequences in another network. Moreover the structures of networks are relevant to the evolution of cooperation.
In this EPJ B colloquium, devoted to evolutionary games on multilayer networks, Zhen Wang and colleagues take into consideration the implications of the fact that humans are usually members of multiple social networks and conclude that the evolution of cooperation is one of the main pillars of modern human societies.
- Published on 13 May 2015
Quantum dots are an ideal nanolab to study the means to turning heat into electricity
Just as alchemists always dreamed of turning common metal into gold, their 19th century physicist counterparts dreamed of efficiently turning heat into electricity, a field called thermoelectrics. Such scientists had long known that in conducting materials the flow of energy in the form of heat is accompanied by a flow of electrons. What they did not know at the time is that it takes nanometric-scale systems for the flow of charge and heat to reach a level of efficiency that cannot be achieved with larger scale systems. Now, in a paper published in EPJ B Barbara Szukiewicz and Karol Wysokiński from Marie Curie-Skłodowska University, in Lublin, Poland have demonstrated the importance of thermoelectric effects, which are not easily modelled, in nanostructures.
- Published on 08 May 2015
A new study shows how a new way of controlling electronic systems endowed with a memory can provide insights into the way associative memories are formed by mimicking synapses
Scientists are attempting to mimic the memory and learning functions of neurons found in the human brain. To do so, they investigated the electronic equivalent of the synapse, the bridge, making it possible for neurons to communicate with each other. Specifically, they rely on an electronic circuit simulating neural networks using memory resistors. Such devices, dubbed memristor, are well-suited to the task because they display a resistance, which depends on their past states, thus producing a kind of electronic memory. Hui Zhao from Beijing University of Posts and Telecommunications, China, and colleagues, have developed a novel adaptive-control approach for such neural networks, presented in a study published in EPJ B. Potential applications are in pattern recognition as well as fields such as associative memories and associative learning.
- Published on 06 May 2015
A new study shows that relatively small external disturbances play a crucial role in chaotic phenomena like the recent Calbuco volcanic eruption in Chile, leading to drum-beat-like seismicity
Volcanoes are considered chaotic systems. They are difficult to model because the geophysical and chemical parameters in volcanic eruptions exhibit high levels of uncertainty. Now, Dmitri V. Alexandrov and colleagues from the Ural Federal University in Ekaterinburg, in the Russian Federation, have further extended an eruption model - previously developed by other scientists - to the friction force at work between the volcanic plug and volcanic conduit surface. The results, published in EPJ B, provide evidence that volcanic activity can be induced by external noises that would not otherwise have been predicted by the model.