Although both mattresses are designed for side sleepers, the Helix Midnight will probably seem like the more obvious choice ...

Regular sales keep the Helix Midnight within a mid-range to upper-mid-range price bracket. We normally see 20% to 25% off, ...

After discounts, the Helix Twilight falls into the mid-range bracket — and it costs the same as other models in Helix's entry-level Core Collection. Right now, a queen Helix Midnight is on sale ...

Semiconservative replication was not the only model of DNA replication proposed during the mid-1950s ... the entire original DNA double helix serves as a template for a new double helix, such ...