No any reason. RoR is great. But as a personal experience, most of my pals who came from the academic area ( Python in scientific programming is beautiful...),

No any reason. RoR is great. But as a personal experience, most of my pals who came from the academic area ( Python in scientific programming is beautiful...), we felt more familiar with Django because, you see, it's more straight to use Python in producing dashboards or other Web based app. But I've personally found that the main thing is to generate backend data (Json, http request...) with Django/RoR and build the fronted with Js. If you want to use in an effective manner your Python skills acquired in scientific programming to build web apps,...I would recommend Django.