How do you Require Login for Media Files in Django

I'm serving "sensitive" information in downloadable PDF's and Spreadsheets within a user registration section of a site.

How to query Android MediaStore Content Provider, avoiding orphaned images?

I'm trying to provide an in-app Activity which displays thumbnails of photos in the device's media store, and allow the user to select one. After the user makes a selection, the application reads the original full-size image and does things with it.

What does -webkit-min-device-pixel-ratio: 2 stand for?

@media only screen and (max-device-width:480px), 

only screen and (-webkit-min-device-pixel-ratio: 2)

{ /*iphone css*/ }