Interplay between finite resources and local defect in an asymmetric simple exclusion process

When particle flux is regulated by multiple factors such as particle supply and varying transport rate, it is important to identify the respective dominant regimes. We extend the well-studied totally asymmetric simple exclusion model to investigate the interplay between a controlled entrance and a local defect site. The model mimics cellular transport phenomena where there is typically a finite particle pool and non-uniform moving rates due to biochemical kinetics. Our simulations reveal regions where, despite an increasing particle supply, the current remains constant while particles redistribute in the system. Exploiting a domain wall approach with mean-field approximation, we provide a theoretical ground for our findings. The results in steady state current and density profiles provide quantitative insights into the regulation of the transcription and translation process in bacterial protein synthesis. We investigate the totally asymmetric simple exclusion model with controlled entrance and a defect site in the bulk to mimic the finite particle pool and non-uniform moving rates in particle transport processes.Comment: 9 pages, 12 figures; v2: minor format changes; v3: major revision, additional references; v4: minor format change to figures, additional reference

Software Process Validation: Quantitatively Measuring the Correspondence of a Process to a Model ; CU-CS-840-97

this article

Discovering Models of Software Processes from Event-Based Data ; CU-CS-819-96

Many software process methods and tools presuppose the existence of a formal model of a process. Unfortunately, developing a formal model for an on-going, complex process can be dicult, costly, and error prone. This presents a practical barrier to the adoption of process technologies, which would be lowered by automated assistance in creating formal models. To this end, we have developed a data analysis technique that we term process discovery. Under this technique, data describing process events are rst captured from an on-going process and then used to generate a formal model of the behavior of that process. In this paper we describe a Markov method that we developed specically for process discovery, as well as describe two additional methods that we adopted from other domains and augmented for our purposes. The three methods range from the purely algorithmic to the purely statistical. We compare the methods and discuss their application in an industrial case study

Power spectra of TASEPs with a localized slow site

The totally asymmetric simple exclusion process (TASEP) with a localized defect is revisited in this article with attention paid to the power spectra of the particle occupancy N(t). Intrigued by the oscillatory behaviors in the power spectra of an ordinary TASEP in high/low density phase(HD/LD) observed by Adams et al. (2007 Phys. Rev. Lett. 99 020601), we introduce a single slow site with hopping rate q<1 to the system. As the power spectrum contains time-correlation information of the particle occupancy of the system, we are particularly interested in how the defect affects fluctuation in particle number of the left and right subsystems as well as that of the entire system. Exploiting Monte Carlo simulations, we observe the disappearance of oscillations when the defect is located at the center of the system. When the defect is off center, oscillations are restored. To explore the origin of such phenomenon, we use a linearized Langevin equation to calculate the power spectrum for the sublattices and the whole lattice. We provide insights into the interactions between the sublattices coupled through the defect site for both simulation and analytical results.Comment: 16 pages, 6 figures; v2: Minor revision

Challenges in evaluating surgical innovation

Research on surgical interventions is associated with several methodological and practical challenges of which few, if any, apply only to surgery. However, surgical evaluation is especially demanding because many of these challenges coincide. In this report, the second of three on surgical innovation and evaluation, we discuss obstacles related to the study design of randomised controlled trials and non-randomised studies assessing surgical interventions. We also describe the issues related to the nature of surgical procedures—for example, their complexity, surgeon-related factors, and the range of outcomes. Although difficult, surgical evaluation is achievable and necessary. Solutions tailored to surgical research and a framework for generating evidence on which to base surgical practice are essential.The Balliol Colloquium has been supported by Ethicon UK with unrestricted educational grants and by the National Institute of Health Research Health Technology Assessment Programme. The Balliol Colloquium was administratively and financially supported by the Nuffield Department of Surgery at the University of Oxford and the Department of Surgery at McGill University. JAC holds a Medical Research Council UK special training fellowship. The University of Aberdeen’s Health Services Research Unit is core funded by the Chief Scientist Offi ce of the Scottish Government Health Directorates. IB is supported by a grant from the Société Française de Rhumatologie and Lavoisier Program (Ministère des Aff aires Etrangères et Européennes). PLE is a DPhil Candidate in Evidence-Based Health Care at Oxford University

A Cooperative Sequential Adsorption Model in Two Dimensions with Experimental Applications for Ionic Self-Assembly of Nanoparticles

Self-assembly of nanoparticles is an important tool in nanotechnology, with numerous applications including thin films, electronics, and drug delivery. We study the deposition of ionic nanoparticles on a glass substrate both experimentally and theoretically. Our theoretical model consists of a stochastic cooperative adsorption and evaporation process on a two-dimensional lattice. By exploring the relationship between the initial concentration of nanoparticles in the colloidal solution and the density of particles deposited on the substrate, we relate the deposition rate of our theoretical model to the concentration.Comment: 7 pages, 6 figures; v2: major revisio