Heterogeneity in testing for infectious diseases

Testing strategies have varied widely between nation states during the COVID-19 pandemic, in intensity as well as methodology. Some countries have mainly performed diagnostic testing while others have opted for mass-screening for the presence of SARS-CoV-2 as well. COVID passport solutions have been introduced, in which access to several aspects of public life requires either testing, proof of vaccination or a combination thereof. This creates a coupling between personal activity levels and testing behaviour which, as we show in a mathematical model, leverages heterogeneous behaviours in a population and turns this heterogeneity from a disadvantage to an advantage for epidemic control

Betonstrategie für den Oresund-Tunnel

A comprehensive concrete specification has been prepared to control the quality of the concrete for the Øresund Link. The required service life of the structure is 100 years in environmental conditions that are aggressive to concrete ; marine environment deicing agents, freeze-thaw action, water pressure etc. This paper gives a short review of the most important requirements for the concrete to be used for the 3,150 m long immersed tunnel from Amager (outside Copenhagen Airport) to an artificial double island south of Saltholm (in the middle of Øresund). The basis for the requirements is shortly commented