The abbreviation byr means "billion years"(109 or 1,000,000,000 years). A closely related abbreviation is bya "billion years ago".

The mathematical theory of plasticity
Microarray Deacetylation Maps Determine Genome-Wide Functions for Yeast Histone Deacetylases
A Practical Guide to Pseudospectral Methods
Nuclear hormone receptor coregulators in action: diversity for shared tasks.
Impact of Transmission Impairments on the Teletraffic Performance of Wavelength-Routed Optical Networks
Optical WDM Networks
Network Innovation using OpenFlow: A Survey
Prevalence and management of late fetal complications following successful selective laser coagulation of chorionic plate anastomose...
Genome-wide binding map of the histone deacetylase Rpd3 in yeast.
Determine Genome-Wide Functions for Yeast Histone Deacetylases