Phase transition

About: Phase transition is a research topic. Over the lifetime, 82824 publications have been published within this topic receiving 1617591 citations. The topic is also known as: phase transition & phase transformation.

Random-Field Instability of the Ordered State of Continuous Symmetry

Abstract: Phase transitions are considered in systems where the field conjugate to the order parameter is static and random. It is demonstrated that when the order parameter has a continuous symmetry, the ordered state is unstable against an arbitrarily weak random field in less than four dimensions. The borderline dimensionality above which mean-field-theory results hold is six. (auth)

Quantum Phase Transitions

Abstract: Part I. Introduction: 1. Basic concepts 2. The mapping to classical statistical mechanics: single site models 3. Overview Part II. Quantum Ising and Rotor Models: 4. The Ising chain in a transverse field 5. Quantum rotor models: large N limit 6. The d = 1, 0 (N greater than or equal to 3) rotor models 7. The d = 2 (N greater than or equal to 3) rotor models 8. Physics close to and above the upper-critical dimension 9. Transport in d = 2 Part III. Other Models: 10. Boston Hubbard model 11. Dilute Fermi and Bose gases 12. Phase transitions of Fermi liquids 13. Heisenberg spins: ferromagnets and antiferromagnets 14. Spin chains: bosonization 15. Magnetic ordering transitions of disordered systems 16. Quantum spin glasses.

Phase transitions in the assembly of multivalent signalling proteins

Abstract: Cells are organized on length scales ranging from angstrom to micrometres. However, the mechanisms by which angstrom-scale molecular properties are translated to micrometre-scale macroscopic properties are not well understood. Here we show that interactions between diverse synthetic, multivalent macromolecules (including multi-domain proteins and RNA) produce sharp liquid-liquid-demixing phase separations, generating micrometre-sized liquid droplets in aqueous solution. This macroscopic transition corresponds to a molecular transition between small complexes and large, dynamic supramolecular polymers. The concentrations needed for phase transition are directly related to the valency of the interacting species. In the case of the actin-regulatory protein called neural Wiskott-Aldrich syndrome protein (N-WASP) interacting with its established biological partners NCK and phosphorylated nephrin, the phase transition corresponds to a sharp increase in activity towards an actin nucleation factor, the Arp2/3 complex. The transition is governed by the degree of phosphorylation of nephrin, explaining how this property of the system can be controlled to regulatory effect by kinases. The widespread occurrence of multivalent systems suggests that phase transitions may be used to spatially organize and biochemically regulate information throughout biology.