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Conjugate coupling-induced spontaneous symmetry breaking (Vol. 50, No. 1)
Spontaneous symmetry breaking (SSB) is a phenomenon that can facilitate the onset of a rich variety of complex patterns observed in several natural systems. In SSB, asymmetric states arise from symmetric systems spontaneously as a control parameter is varied. This study reveals the existence of spontaneous symmetry breaking state induced by conjugate coupling which corresponds to coupling in paradigmatic Stuart-Landau oscillators. The system exhibits distinct dynamical states, namely in-phase synchronized (IPS), out-of-phase synchronized (OPS), nontrivial amplitude death (NAD) and oscillation death (OD) states. We have deduced the explicit analytical solutions of these states and have studied their stability. The system also exhibits multistabilities among the dynamical states including IPS-OPS (R1), OPS-NAD (R2), SSB-NAD (R3), NAD-OD (R4) and SSB-NAD-OPS (R5). It is known that feedback is a useful control mechanism in many biological systems. While introducing the feedback factor in a conjugately coupled system it completely suppresses the SSB and OD states but does not influence the NAD state. These results will shed light on the dynamics of SSB and the control of such dynamical states.
K. Ponrasu, K. Sathiyadevi, V. K. Chandrasekar and M. Lakshmanan, Conjugate coupling-induced symmetry breaking and quenched oscillations, EPL 124, 20007 (2018)
[Abstract]
Wetting routes of droplet upon patterned hydrophilic surface (Vol. 50, No. 1)
The wetting transition of the droplet on the patterned hydrophilic surface can occur spontaneously and may further lead to superwetting that has the potential to develop novel technologies in the field of anti-fogging, printing and heat transfer. However, it is still unknown how the wetting transition occurs on such a patterned surface. In contrast to the conventional view that wetting occurs immediately in the vertical direction upon the contact of the droplet with the solid surface due to the capillary force, we find that the droplet spreads first in the horizontal direction if the patterned surface has a large enough roughness. Then, the wetting transition occurs at the periphery rather than at the middle part of droplet, which is termed as “one-dimensional wetting”. We ascribe such an interesting phenomenon to the competition between the horizontal force arising from the non-equilibrium surface tension and the vertical capillary force as well as to the different pressure under the droplet, which lead to three different wetting routes (one-dimension wetting (One), two dimension wetting (Two), Between one and two dimension wetting (BOT)).
T. Li, X. Liu, H. Zhao, B. Zhang and L. Wang, Counterintuitive wetting route of droplet on patterned hydrophilic surface, EPL 123, 36003 (2018)
[Abstract]
Making plasma medicine available for in-body applications (Vol. 50, No. 1)
Ever since non-thermal plasmas showed efficacy in decontamination and wound healing, the idea of deploying plasma medical therapy within the human body emerges. Besides the need for flexibility, small dimensions and biological effectiveness, also a minimal plasma-caused applicator erosion as well as an electrically safe operation mode are necessary. Of course, the endoscopic plasma source must also operate inside hollow cavities independent of the environmental conditions present. Since all requirements need to be fulfilled at the same time, the development task is quite complex.
The present paper tackles those requirements and sets special focus on new approaches for reducing leakage current, increasing the bactericidal efficacy and avoiding material erosion simultaneously. The jet-like plasma at the tube tip is maintained by a capacitively coupled discharge configuration. An additional shielding gas surrounds the jet in order to assure reproducible environmental conditions inside the body. Finally, it is found that a combination of Neon feed gas, CO2 shielding gas and a current limited high voltage supply gives the best bactericidal results and, at the same time, reduces material erosion as well as patient leakage current.
J. Winter, Th. M. C. Nishime, R. Bansemer , M. Balazinski, K. Wende and K.-D. Weltmann, Enhanced atmospheric pressure plasma jet setup for endoscopic applications, J. Phys. D: Appl. Phys. 52, 024005 (2019)
[Abstract]
Factors affecting turbulence scaling (Vol. 50, No. 1)
Study focuses on hydrodynamic effects of external disturbances on fluids at critical points, including inconsistent turbulence in all directions, or anisotropy, and varying degrees of compressibility
Fluids exhibiting scaling behaviour can be found in diverse physical phenomena occurring both in the laboratory and in real-world conditions. For instance, they occur at the critical point when a liquid becomes a vapour, at the phase transition of superfluids, and at the phase separation of binary liquids whose components exhibit two different types of behaviour. Until now, models have not fully taken the effect of external turbulences into account. In a recent study published recently, the authors investigate the influence of ambient turbulent speed fluctuations in physical systems when they reach a critical point. These fluctuations are found to be the result of a lack of spatial regularity in these systems, or anisotropy, and of the compressibility of fluids. What is unique about this study is that the turbulence introduced in the model is novel and helps to elucidate the extent to which the speed of these fluctuations affects their scaling behaviour.
M. Hnatič, G. Kalagov, and T. Lučivjanský, Scaling behavior in interacting systems: joint effect of anisotropy and compressibility, Eur. Phys. J. B, 91, 269 (2018)
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