Convex output feedback model predictive control for mitigation of COVID-19 pandemic.

In this paper, a model predictive control approach is proposed for epidemic mitigation. The disease spreading dynamics is described by an 8-compartment smooth nonlinear model of the COVID-19 pandemic in Hungary known from the literature, where the manipulable control input is the stringency of the introduced non-pharmaceutical measures. It is assumed that only the number of hospitalized people is measured on-line, and the other state variables are computed using a state observer which is based on the dynamic inversion of a linear sub-system of the model. The objective function contains a measure of the direct harmful consequences of the restrictions, and the constraints refer to input bounds and to the capacity of the healthcare system. By exploiting the special properties of the model, the nonlinear optimization problem required by the control design is reformulated to convex tasks, allowing a computationally efficient solution. Two approaches are proposed: the first finds a suboptimal solution by geometric programming, while the second one further simplifies the problem and transforms it to a linear programming task. Simulations show that both suboptimal solutions fulfill the design specifications even in the presence of parameter uncertainties.

Breast cancer inequities between Maori and non-Maori women in Aotearoa/New Zealand.

Maori women have one of the highest incidences of breast cancer in the world. This high incidence is generally unexplained although higher rates of obesity and alcohol intake are modifiable risk factors that may be important. Maori women are less likely to attend mammographic breast screening and are likely to be diagnosed with more advanced disease. This is one of the reasons for the excess mortality. Another factor is differences in the treatment pathway. Maori women are more likely to experience delay in receiving treatment, are less likely to receive radiotherapy, are more likely to be treated with a mastectomy and are less likely to adhere to long-term adjuvant endocrine therapy. However, genetic factors in Maori women do not seem to impact significantly on mortality. This review looks at the inequity between Maori and non-Maori women and addresses the causes. It proposes ways of reducing inequity through primary prevention, increased participation in breast screening and greater standardisation of the treatment pathway for women newly diagnosed with breast cancer. We believe that health system improvements will decrease barriers to health care participation for Maori women and suggest that further research into identifying and modifying obstacles within health systems is required.