Better together: mobile and security

Growing up, there was a very specific sandwich-making rule laid down by my dad. When making peanut butter and jelly sandwiches, you had to use the peanut butter before the jelly. Was this because of some principle which determined that the resulting sandwich held together better when the ingredients were applied in this order? No. It was because he hated the cross-contamination of jelly into the peanut butter jar which was inevitable when it was on the spreading knife first.Read more