43 research outputs found
Information theory explanation of the fluctuation theorem, maximum entropy production and self-organized criticality in non-equilibrium stationary states
Jaynes' information theory formalism of statistical mechanics is applied to
the stationary states of open, non-equilibrium systems. The key result is the
construction of the probability distribution for the underlying microscopic
phase space trajectories. Three consequences of this result are then derived :
the fluctuation theorem, the principle of maximum entropy production, and the
emergence of self-organized criticality for flux-driven systems in the
slowly-driven limit. The accumulating empirical evidence for these results
lends support to Jaynes' formalism as a common predictive framework for
equilibrium and non-equilibrium statistical mechanics.Comment: 21 pages, 0 figures, minor modifications, version to appear in J.
Phys. A. (2003
How do we engage people in testing for COVID-19? A rapid qualitative evaluation of a testing programme in schools, GP surgeries and a university
Abstract Background The UK Scientific Advisory Group for Emergencies (SAGE) emphasises the need for high levels of engagement with communities and individuals to ensure the effectiveness of any COVID-19 testing programme. A novel pilot health surveillance programme to assess the feasibility of weekly community RT-LAMP (Reverse transcription loop-mediated isothermal amplification) testing for the SARS-CoV-2 virus using saliva samples collected at home was developed and piloted by the University of Southampton and Southampton City Council. Methods Rapid qualitative evaluation was conducted to explore experiences of those who took part in the programme, of those who declined and of those in the educational and healthcare organisations involved in the pilot testing who were responsible for roll-out. This included 77 interviews and 20 focus groups with 223 staff, students, pupils and household members from four schools, one university, and one community healthcare NHS trust. The insights generated and informed the design and modification of the Southampton COVID-19 Saliva Testing Programme and the next phase of community-testing. Results Discussions revealed that high levels of communication, trust and convenience were necessary to ensure people’s engagement with the programme. Participants felt reassured by and pride in taking part in this novel programme. They suggested modifications to reduce the programme’s environmental impact and overcome cultural barriers to participation. Conclusions Participants’ and stakeholders’ motivations, challenges and concerns need to be understood and these insights used to modify the programme in a continuous, real-time process to ensure and sustain engagement with testing over the extended period necessary. Community leaders and stakeholder organisations should be involved throughout programme development and implementation to optimise engagement. </jats:sec
Revisiting the Gaia Hypothesis: Maximum Entropy, Kauffman’s ‘Fourth Law’ and Physiosemeiosis
Recently, Kleidon suggested to analyze Gaia as a non-equilibrium
thermodynamic system that continuously moves away from equilibrium, driven by
maximum entropy production which materializes in hierarchically coupled
mechanisms of energetic flows via dissipation and physical work. I relate this
view with Kauffman's 'Fourth Law of Thermodynamics', which I interprete as a
proposition about the accumulation of information in evolutionary processes.
The concept of physical work is expanded to including work directed at the
capacity to work: I offer a twofold specification of Kauffman's concept of an
'autonomous agent', one as a 'self-referential heat engine', and the other in
terms of physiosemeiosis, which is a naturalized application of Peirce's theory
of signs. The conjunction of these three theoretical sources, Maximum Entropy,
Kauffman's Fourth Law, and physiosemeiosis, shows that the Kleidon restatement
of the Gaia hypothesis is equivalent to the proposition that the biosphere is
generating, processing and storing information, thus directly treating
information as a physical phenomenon. There is a fundamental ontological
continuity between the biological processes and the human economy, as both are
seen as information processing and entropy producing systems. Knowledge and
energy are not substitutes, with energy and information being two aspects of
the same underlying physical process
Maximum Entropy Production as an Inference Algorithm that Translates Physical Assumptions into Macroscopic Predictions: Don’t Shoot the Messenger
Is Maximum Entropy Production (MEP) a physical principle? In this paper I tentatively suggest it is not, on the basis that MEP is equivalent to Jaynes’ Maximum Entropy (MaxEnt) inference algorithm that passively translates physical assumptions into macroscopic predictions, as applied to non-equilibrium systems. MaxEnt itself has no physical content; disagreement between MaxEnt predictions and experiment falsifies the physical assumptions, not MaxEnt. While it remains to be shown rigorously that MEP is indeed equivalent to MaxEnt for systems arbitrarily far from equilibrium, work in progress tentatively supports this conclusion. In terms of its role within non-equilibrium statistical mechanics, MEP might then be better understood as Messenger of Essential Physics
Maximum entropy production and plant optimization theories
Plant ecologists have proposed a variety of optimization theories to explain the adaptive behaviour and evolution of plants from the perspective of natural selection (‘survival of the fittest’). Optimization theories identify some objective function—such as shoot or canopy photosynthesis, or growth rate—which is maximized with respect to one or more plant functional traits. However, the link between these objective functions and individual plant fitness is seldom quantified and there remains some uncertainty about the most appropriate choice of objective function to use. Here, plants are viewed from an alternative thermodynamic perspective, as members of a wider class of non-equilibrium systems for which maximum entropy production (MEP) has been proposed as a common theoretical principle. I show how MEP unifies different plant optimization theories that have been proposed previously on the basis of ad hoc measures of individual fitness—the different objective functions of these theories emerge as examples of entropy production on different spatio-temporal scales. The proposed statistical explanation of MEP, that states of MEP are by far the most probable ones, suggests a new and extended paradigm for biological evolution—‘survival of the likeliest’—which applies from biomacromolecules to ecosystems, not just to individuals
