Self-Assembly of Spiral Patterns in Confined System with Competing Interactions

Colloidal particles in polymer solutions and functionalized nanoparticles often exhibit short-range attraction coupled with long-range repulsion (SALR) leading to the spontaneous formation of symmetric patterns. Chiral nanostructures formed by thin film of SALR particles have not been reported yet. In this study, we observe striking topological transitions from a symmetric pattern of concentric rings to a chiral structure of a spiral shape, when the system is in hexagonal confinement. We find that the spiral formation can be induced either by breaking the system symmetry with a wedge, or by melting of the rings. In the former case, the chirality of the spiral is determined by orientation of the wedge and thus can be controlled. In the latter, the spiral rises due to thermally induced defects and is absent in the average particle distribution that form highly regular hexagonal patterns in the central part of the system. These hexagonal patterns can be explained by interference of planar density waves. Thermodynamic considerations indicate that equilibrium spirals can appear spontaneously in any stripe-forming system confined in a hexagon with a small wedge, provided that certain conditions are satisfied by a set of phenomenological parameters

Formation of Liesegang patterns: Simulations using a kinetic Ising model

A kinetic Ising model description of Liesegang phenomena is studied using Monte Carlo simulations. The model takes into account thermal fluctuations, contains noise in the chemical reactions, and its control parameters are experimentally accessible. We find that noisy, irregular precipitation takes place in dimension d=2 while, depending on the values of the control parameters, either irregular patterns or precipitation bands satisfying the regular spacing law emerge in d=3.Comment: 7 pages, 8 ps figures, RevTe

#Rezist 2017: Communicating Dissent in a Hypermedia Environment

Protest communication and campaigning plays a crucial role in democracy, and can bring about regime change, yet is treated as of secondary importance to electioneering activities. This paper counters the imbalance by focusing on the #Rezist protests in Romania 2017; triggered by an attempt by government to exonerate senior politicians who had been found guilty of corruption. Young Romanians took control of Victory Square, facing the government building, to demand the law be repealed and European law be respected. In order to counter the government narrative which dominated party supportive media, protesters quickly developed their own media channels to build support. The protests spread across Romania and the diaspora; the younger, entrepreneurial class gained the attention required to bring about short-term changes. Through interviews with some of the key activists and monitoring of developments in the anticorruption campaign we chart the role social media plays in building the e motional mood and sense of solidarity required to meet short term goals. But equally our analysis shows that once short term objectives are attained the c ampaigns that bring together Internet-mediated issue generalists can become fragile. Hence this paper offers a more balanced perspective of Internet-mediated social movements than studies of Castells and others. Our study serves to highlight how protests can emerge through the emotional power of outrage, can mobilise citizens around narrow objectives, and can evolve to become a social movement, but then struggle to then develop a more transformatory socio-political agenda