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ACTIVE MATTER

Definition

(from kitp/ucsb) Active matter is a class of non-equilibrium, many-body systems that consist of individual energy-transducing components. The collective dynamics of such active entities underlies phenomena on scales from the molecular to the macroscopic, and it includes both living and non-living systems. The field of active matter focuses on understanding how the collective behaviors of internally driven components can give rise to patterns of motion and stress on large scales. While active matter systems violate detailed balance at the molecular scale, it remains unclear how such non-equilibrium dynamics manifests itself and can be quantified at meso- and macroscopic scales. In particular, it is interesting to investigate, given a particular set of microscopic elementary units, what range of possible macroscopic patterns, structures, dynamics and functionalities can be realized.

(from wikipedia) Active matter is composed of large numbers of active “agents”, each of which consumes energy in order to move or to exert mechanical forces.[1][2] Due to the energy consumption, these systems are intrinsically out of thermal equilibrium. Examples of active matter are schools of fish, flocks of birds, bacteria, artificial self-propelled particles, and self-organising bio-polymers such as microtubules and actin, both of which are part of the cytoskeleton of living cells. Most examples of active matter are biological in origin; however, a great deal of current experimental work is devoted to synthetic systems. Active matter is a relatively new material classification in soft matter: the most extensively studied model, the Vicsek model, dates from 1995.

(from rheology of complex fluids / springer) The term active matter describes diverse systems, spanning macroscopic (e.g., shoals of fish and flocks of birds) to microscopic scales (e.g., migrating cells, motile bacteria and gels formed through the interaction of nanoscale molecular motors with cytoskeletal filaments within cells). Such systems are often idealizable in terms of collections of individual units, referred to as active particles or self-propelled particles, which take energy from an internal replenishable energy depot or ambient medium and transduce it into useful work performed on the environment, in addition to dissipating a fraction of this energy into heat. These individual units may interact both directly and through disturbances propagated via the medium in which they are immersed. Active particles can exhibit remarkable collective behavior as a consequence of these interactions, including non-equilibrium phase transitions between novel dynamical phases, large fluctuations violating expectations from the central limit theorem and substantial robustness against the disordering effects of thermal fluctuations.

Papers

2012 - Soft Active Matter (marchetti, joanny & al) - https://arxiv.org/abs/1207.2929

People

Jean-François Joanny (ESPCI, COLLEGE DE FRANCE, CURIE)

Jean-Francois Rupprecht (CNRS)

M. Cristina Marchetti ( UCSB )

Keywords

  • self-phoretic colloids
  • nematics
  • auxetics
  • rheology

Conferences

active_matter.txt · Last modified: 2019/12/06 11:24 by admin