alumnus (male singular), alumna (female singular), alumni (male OR mixed plural), alumnae (female plural)

Don't use them, even in headlines. 

Exceptions:

• specific abbrevations, such as R&D
• the CERN & Society Foundation
• certain company names – Smith & Jones Consulting
• when artistic considerations dictate – on a logo, for example 
• academic references – (Grant & Smith, 1998)

but analog in a computing context

of radios