On metric-preserving functions and fixed point theorems
  Kirk and Shahzad have recently given fixed point theorems concerning local radial contractions and metric transforms. In this article, we replace the metric transforms by metric-preserving functions. This in turn gives several extensions of the main results given by Kirk and Shahzad. Several examples are given. The fixed point sets of metric transforms and metric-preserving functions are also investigated. 
Prapanpong Pongsriiam and Imchit Termwuttipong
math.CA