how to make ubunto iso bootable on a usb stick with mac

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http://askubuntu.com – Is there any way to make a bootable ubuntu usb stick from an ubuntu iso image in OSX? I have a Macbookpro and I'm planning to create a multiple boot. I've already created the necessary partitions and downloaded the ubuntu iso image file: ubuntu-12.04.1-desktop-i386.iso When I try to create a bootable usb stick from the iso file, by means of "recovering" the disk image into the usb drive using disk image utility, I get the following message: Could not validate source - corrupt image The disk image can't be mounted in osx either, I also get a similar message. Is there any way to make a boo (HowTos)