scholarly journals Boundary-induced abrupt transition in the symmetric exclusion process

2008 ◽  
Vol 77 (6) ◽  
Author(s):  
Apoorva Nagar ◽  
Meesoon Ha ◽  
Hyunggyu Park
Author(s):  
R.A Walker ◽  
S. Inoue ◽  
E.D. Salmon

Microtubules polymerized in vitro from tubulin purified free of microtubule-associated proteins exhibit dynamic instability (1,2,3). Free microtubule ends exist in persistent phases of elongation or rapid shortening with infrequent, but, abrupt transitions between these phases. The abrupt transition from elongation to rapid shortening is termed catastrophe and the abrupt transition from rapid shortening to elongation is termed rescue. A microtubule is an asymmetrical structure. The plus end grows faster than the minus end. The frequency of catastrophe of the plus end is somewhat greater than the minus end, while the frequency of rescue of the plus end in much lower than for the minus end (4).The mechanism of catastrophe is controversial, but for both the plus and minus microtubule ends, catastrophe is thought to be dependent on GTP hydrolysis. Microtubule elongation occurs by the association of tubulin-GTP subunits to the growing end. Sometime after incorporation into an elongating microtubule end, the GTP is hydrolyzed to GDP, yielding a core of tubulin-GDP capped by tubulin-GTP (“GTP-cap”).


Somatechnics ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 9-30
Author(s):  
Fiona K. O'Neill

In the UK, when one is suspected of having breast cancer there is usually a rapid transition from being diagnosed, to being told you require treatment, to this being effected. Hence, there is a sense of an abrupt transition from ‘normal’ embodiment through somatechnic engagement; from normality, to failure and otherness. The return journey to ‘embodied normality’, if indeed there can be one, is the focus of this paper; specifically the durée and trajectory of such normalisation. I offer a personal narrative from encountering these ‘normalising interventions’, supported by the narratives of other ‘breast cancer survivors’. Indeed, I havechosento become acquainted with my altered/novel embodiment, rather than the symmetrisation of prosthetication, to ‘wear my scars’,and thus subvert the trajectory of mastectomy. I broach and brook various encounters with failure by having, being and doing a body otherwise; exploring, mastering and re-capacitating my embodiment, finding the virtuosity of failure and subversion. To challenge the durée of ‘normalisation’ I have engaged in somatic movement practices which allow actual capacities of embodiment to be realised; thorough kinaesthetic praxis and expression. This paper asks is it soma, psyche or techné that has failed me, or have I failed them? What mimetic chimera ‘should’ I become? What choices do we have in the face of failure? What subversions can be allowed? How subtle must one be? What referent shall I choose? What might one assimilate? Will mimesis get me in the end? What capacities can one find? How shall I belong? Where / wear is my fidelity? The hope here is to address the intra-personal phenomenological character and the inter-corporeal socio-ethico-political aspects that this body of failure engenders, as one amongst many.


2020 ◽  
Vol 75 (5) ◽  
pp. 449-463
Author(s):  
Dominik Lips ◽  
Artem Ryabov ◽  
Philipp Maass

AbstractDriven diffusive systems constitute paradigmatic models of nonequilibrium physics. Among them, a driven lattice gas known as the asymmetric simple exclusion process (ASEP) is the most prominent example for which many intriguing exact results have been obtained. After summarising key findings, including the mapping of the ASEP to quantum spin chains, we discuss the recently introduced Brownian ASEP (BASEP) as a related class of driven diffusive system with continuous space dynamics. In the BASEP, driven Brownian motion of hardcore-interacting particles through one-dimensional periodic potentials is considered. We study whether current–density relations of the BASEP can be considered as generic for arbitrary periodic potentials and whether repulsive particle interactions other than hardcore lead to similar results. Our findings suggest that shapes of current–density relations are generic for single-well periodic potentials and can always be attributed to the interplay of a barrier reduction, blocking, and exchange symmetry effect. This implies that in general up to five different phases of nonequilibrium steady states are possible for such potentials. The phases can occur in systems coupled to particle reservoirs, where the bulk density is the order parameter. For multiple-well periodic potentials, more complex current–density relations are possible, and more phases can appear. Taking a repulsive Yukawa potential as an example, we show that the effects of barrier reduction and blocking on the current are also present. The exchange symmetry effect requires hardcore interactions, and we demonstrate that it can still be identified when hardcore interactions are combined with weak Yukawa interactions. The robustness of the collective dynamics in the BASEP with respect to variations of model details can be a key feature for a successful observation of the predicted current–density relations in actual physical systems.


Author(s):  
Leonid Petrov ◽  
Axel Saenz

AbstractWe obtain a new relation between the distributions $$\upmu _t$$ μ t at different times $$t\ge 0$$ t ≥ 0 of the continuous-time totally asymmetric simple exclusion process (TASEP) started from the step initial configuration. Namely, we present a continuous-time Markov process with local interactions and particle-dependent rates which maps the TASEP distributions $$\upmu _t$$ μ t backwards in time. Under the backwards process, particles jump to the left, and the dynamics can be viewed as a version of the discrete-space Hammersley process. Combined with the forward TASEP evolution, this leads to a stationary Markov dynamics preserving $$\upmu _t$$ μ t which in turn brings new identities for expectations with respect to $$\upmu _t$$ μ t . The construction of the backwards dynamics is based on Markov maps interchanging parameters of Schur processes, and is motivated by bijectivizations of the Yang–Baxter equation. We also present a number of corollaries, extensions, and open questions arising from our constructions.


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