These are the stock wallpapers bundled with Android 5 ( Lollipop) on the Nexus 7. The resolution is good enough (probably even better) to use them for your desktop PC or lap top, because the Nexus packs a display with resolution of 1920×1200. So each of the eleven wallpapers has a greater resolution than that.
I like the clean, minimalistic look to them and they go along quite well with a Windows 8 OS.