Constitutive modelling of viscoplasticity incorporating non-proportional hardening effects.

Statistical modelling of biomarkers incorporating non-proportional effects for survival data

Personalised medicine is replacing the one-drug-fits-all approach with many prognostic models incorporating biomarkers available for risk stratifying patients with breast cancer, such as the Nottingham Prognostic Index and Adjuvant! Online and more recently multiparameter assays, OncotypeDx and Mammaprint. Evidence of biomarkers having non-proportional effects have been emerging and therefore v...

Ordinal regression modelling between proportional odds and non-proportional odds

Robust Frailty Modelling using Non-Proportional Hazards Models

Correlated survival times can be modelled by introducing a random effect, or frailty component, into the hazard function. For multivariate survival data we extend a non-PH model, the generalized time-dependent logistic survival model, to include random effects. The hierarchical-likelihood procedure, which obviates the need for marginalization over the random effect distribution, is derived for ...

Viscoplasticity and large-scale chain relaxation in glassy-polymeric strain hardening.

A simple theory for glassy-polymeric mechanical response that accounts for large-scale chain relaxation is presented. It captures the crossover from perfect-plastic response to Gaussian strain hardening as the degree of polymerization N increases, without invoking entanglements. By relating hardening to interactions on the scale of monomers and chain segments, we correctly predict its magnitude...

Power - proportional modelling fidelity

Traditional hierarchical modelling methods tend to have layers of abstraction corresponding to naturally existing layers of concern in multilevel systems. Although convenient, this is not always optimal for analysis and design. For instance, parts of a system which are in the same layer may not contribute to the same degree on some metric, e.g. system power consumption. To moderate the modellin...