In this paper, we derive a discretized multi-group epidemic model with time delay by using a nonstandard finite difference (NSFD) scheme. A crucial observation regarding the advantage of the NSFD scheme is that the positivity and boundedness of solutions of the continuous model are preserved. Furthermore, we show that the discrete model has the same equilibria, and the conditions for their stab...

In light of escalating job insecurity due to increasing numbers of nonstandard workers, this study examined the association between nonstandard employment and mental health among South Korean workers. We analyzed a representative weighted sample of 2086 men and 1194 women aged 20-64 years, using data from the 1998 Korean National Health and Nutrition Examination Survey. Nonstandard employment i...

We exhibit an aggressive optimizing compiler for a functionalprogramming language which includes a first-class forward automatic differentiation (AD) operator. The compiler’s performance is competitive with FORTRAN-based systems on our numerical examples, despite the potential inefficiencies entailed by support of a functional-programming language and a first-class AD operator. These results ar...