Up to 40% of northeastern Asians experience flushing and elevated heart rate after drinking even minimal amounts of alcohol, due to accumulation of acetaldehyde. This is because of a mutation in acetaldehyde dehydrogenase (ALDH2), the enzyme that converts acetaldehyde to acetate.
When you use Outlook, the operating system saves your files in the \Documents and Settings\ directory for your user name. This directory saves some user-specific configurations, including the contact files used in your Outlook installation. Each Outlook file can be identified by its extension. Contacts are saved with the \.pab\ file extension.
A file extension is part of the file name and uniquely identifies the type of file, also referred to as the format. When your instructor receives your e-mail and sees your file with a .doc extension, she knows that you are sending her a Word document.