Adopting standard assumptions, Λ is proportional to the frequency of infectious individuals, the proportionality constant being the transmission coefficient,
Interactions between all variables were investigated and the assumption of proportional hazards was tested by including time dependent variables in the model.
The time dependent covariate method was used to check the proportional hazard assumption of the model; an extended Cox model was constructed, adding interaction terms that involve time, that is, time dependent variables, computed as the by-product of time and individual covariates in the model (time × covariate).
Time dependent variables were forced in the model.
To investigate the effect of walking speed, an interaction variable of walking speed and progression of the walking tour (represented by the fixed time-dependent variable) was added to the model.
We denote by a time-dependent variable that represents the data points of p i. To compute the values of at the time points, we first set to be.
The proportional hazards assumption was verified by adding a time-dependent variable to the model.
In this setting, a trivial solution is a solution which is constant with respect to the moving frame defined by the time-dependent change of variable ( x, y ) ↦ ( A ( t ) x, B ( t ) y ).
The constraint that appears in (3.1) forces the motion to occur on a manifold M : = { ( p, q ) ∈ R m × R s : g ( p, q ) = 0 } that moves integrally to a reference frame defined by the time-dependent change of variable ( x, y ) ↦ ( A ( t ) x, B ( t ) y ).
Furthermore, we proposed a homogenous Landau-type model to describe the response of storage modulus during aging by introducing a time-dependent variable coupled with the order parameter.
