In this article, we model the dependence between dam factor and D
max, where dam factor is an indicator of risk of a tailings dam failure, which involves the height H of the tailings dam, the volume of material housed by the tailings dam VT and the volume dispensed by the tailings dam, VF, when the dam breaks. And, Dmax is the maximum distance traveled by the material released by the tailings dam, after the collapse. With the dependence found via copula models and Bayesian estimation, given a range of dam factor, we estimate the probability of the released material to exceed a certain threshold. Since the dam factor involves the released volume VF (unknown before the dam break), we present a naive way to estimate it using VT and H. In this way, it is possible to estimate the dam factor of a tailings dam and with such a value to identify the probability of the tailings dam to show a Dmax that exceeds a certain threshold.
This study aims to report analyses regarding the global distribution of institutions involved in clinical trials of COVID-19 vaccines throughout February 2022. We retrieved global data from the World Health Organization report on vaccine development. These data allowed us to identify project institutions and plot their geographic coordinates. We produced a georeferenced map using an R programming environment and, based on the geographical location of vaccine developers, we analyzed the subcontinental distribution of clinical trials and the nature of the vaccines. Regionally, South-Southeast Asian countries carried out more clinical trials than any other region, proportionally, although this happened solely for mature technologies. Few trials were under implementation in Latin America and Africa. Our findings confirm previous studies on the regional concentration in the development of technology. However, our contribution lies in showing these phenomena for COVID-19 vaccines in specific subcontinents and technologies, at a country level. Our data underscores which subcontinents perform very few clinical trials for COVID-19 and seem to be ill-prepared for future disease outbreaks, and if these become epidemics or even pandemics and require domestic vaccine development or production. We also consider the case of Brazil, which did not finish the complete cycle of COVID-19 vaccine development in the indicated period; but, with favorable policies, it has potential to engage further in COVID-19 vaccine technology.
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