- 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.
- Published on 18 March 2015
Developing a new approach to quantum computing, based on braided quasi-particles as a logic gate to speed up computing, first requires understanding the potential error-inducing factors
What does hair styling have in common with quantum computing? The braiding pattern has inspired scientists as a potential new approach to quantum calculation. The idea is to rely on a network of intersecting chains, or nanowires, containing one-dimensional quasi-particles. The way these quasi-particles evolve in space time produces a braid-like pattern. These braids could then be used as the logic gate that provides the logical function required for calculations in computers. Due to their intrinsic properties, such braids are much more difficult to destabilise and less error-prone. Yet, local defects can still arise along nanowires. In a study published in EPJ B, Jelena Klinovaja affiliated with both the University of Basel, Switzerland and Harvard University, Cambridge, MA, USA, and Daniel Loss from the University of Basel, Switzerland identify the potential sources of computer errors arising from these defects.
- Published on 13 March 2015
It is now theoretically possible to remotely control the direction in which magnetic molecules spin, which opens the door to designing applications based on molecular motors
In the eyes of physicists, magnetic molecules can be considered as nanoscale magnets. Remotely controlling the direction in which they rotate, like spinning tops, may intuitively be difficult to achieve. However, Russian physicists have just demonstrated that it is theoretically possible to do so. They have shown that a change of direction in the circular polarisation of an external magnetic field leads to a change in the direction of the mechanical rotation of the molecule. These findings by Iosif Davidovich Tokman and Vera Il‘inichna Pozdnyakova from the Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, Russia, were recently published in EPJ B. Possible applications of the phenomenon include rotating magnetic molecules used as molecular rotors to power molecular motors.
- Published on 16 February 2015
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.
Kyu-Min Lee, Byungjoon Min and Kwang-Il Goh (2015),
Towards real-world complexity: an introduction to multiplex networks,
European Physical Journal B, DOI: 10.1140/epjb/e2015-50742-1