Usage-driven problem design for radical innovation in healthcare

While the diffusion and evaluation of healthcare innovations receive a lot of attention, the early design stages are less studied and potential innovators lack methods to identify where new innovations are necessary and to propose concepts relevant to users. To change this, we propose a structured methodology, Radical Innovation Design (RID), which supports designers who want to work on the unstated needs of potential end users in order to create superior value. In this article, the first part of RID is introduced with its two subprocesses: Problem Design and Knowledge Design. In this first period, RID guides innovators to systematically explore users’ problems and evaluate which ones are most pressing in terms of innovation, taking into account existing solutions. The result is an ambition perimeter, composed of a set of value buckets, that is, important usage situations where major problems are experienced and the current solutions provide little or no relief. The methodology then moves on to Solution Design and Business Design (which are not detailed in this article) to address the value buckets identified. With its emphasis on problem exploration, RID differs from methods based on early prototyping. The RID methodology has been validated in various industrial sectors and is well-adapted for healthcare innovation. To exemplify the methodology, we present a case study in dental imagery performed by 10 students in 8 weeks. This example demonstrates how RID favours efficiency in Problem Design and allows designers to explore unaddressed and sometimes undeclared user needs.</jats:p

Adapting the fbs model of designing for usage-driven innovation processes

There has been rising interest in confronting formal models of design with practical design methods, in order to understand better both and to explore how they can improve each other. In this article, we try to map the Radical Innovation Design (RID) methodology in Gero’s Function-Behavior-Structure (FBS) framework. We encounter difficulties in doing so, and propose new constructs extending the FBS framework to account for some processes in RID. For instance, FBS is extended to describe the early stages of RID, where usages are analyzed to identify the appropriate situations and problems on which to innovate. We present a short practical case study to illustrate the relevance of these concepts. Our findings join those of others who have investigated the use of FBS to illustrate innovative projects, where requirements are unclear. We propose perspectives for future research, notably pursuing this work with the situated FBS framework.</jats:p

The bend stiffness of S-DNA

We formulate and solve a two-state model for the elasticity of nicked, double-stranded DNA that borrows features from both the Worm Like Chain and the Bragg--Zimm model. Our model is computationally simple, and gives an excellent fit to recent experimental data through the entire overstretching transition. The fit gives the first value for the bending stiffness of the overstretched state as about 10 nm*kbt, a value quite different from either B-form or single-stranded DNA.Comment: 7 pages, 1 figur

A two-state kinetic model for the unfolding of single molecules by mechanical force

We investigate the work dissipated during the irreversible unfolding of single molecules by mechanical force, using the simplest model necessary to represent experimental data. The model consists of two levels (folded and unfolded states) separated by an intermediate barrier. We compute the probability distribution for the dissipated work and give analytical expressions for the average and variance of the distribution. To first order, the amount of dissipated work is directly proportional to the rate of application of force (the loading rate), and to the relaxation time of the molecule. The model yields estimates for parameters that characterize the unfolding kinetics under force in agreement with those obtained in recent experimental results (Liphardt, J., et al. (2002) {\em Science}, {\bf 296} 1832-1835). We obtain a general equation for the minimum number of repeated experiments needed to obtain an equilibrium free energy, to within $k_BT$, from non-equilibrium experiments using the Jarzynski formula. The number of irreversible experiments grows exponentially with the ratio of the average dissipated work, \bar{\Wdis}, to $k_BT$.}Comment: PDF file, 5 page

Evidence for the Universal Scaling Behaviour of a Freely Relaxing DNA Molecule

Relaxation measurements on a fluorescently labelled free DNA molecule after stretching by a Poiseuille flow in a capillary vessel reveal universal scaling features: at intermediate times the scaling exponent of the decay law for the molecule length as a function of time is found to be 0.51 +/- 0.05. This law is in agreement with the prediction of the Brochard-Wyart "stem and flower" model for the relaxation of a stretched polymer chain.Molecular and Cellular BiologyPhysic

Discrete elastic model for stretching-induced flagellar polymorphs

Force-induced reversible transformations between coiled and normal polymorphs of bacterial flagella have been observed in recent optical-tweezer experiment. We introduce a discrete elastic rod model with two competing helical states governed by a fluctuating spin-like variable that represents the underlying conformational states of flagellin monomers. Using hybrid Brownian dynamics Monte-Carlo simulations, we show that a helix undergoes shape transitions dominated by domain wall nucleation and motion in response to externally applied uniaxial tension. A scaling argument for the critical force is presented in good agreement with experimental and simulation results. Stretching rate-dependent elasticity including a buckling instability are found, also consistent with the experiment