2000s in the music industry Inc.), who surpassed Wal-Mart to become the US’s largest music retailer in April 2008. Sector leaders include: Many hundreds more stores operate worldwide, often prominent only in particular countries or specialist genres. A third kind of operator never retails directly to the public, instead offering branded whitelabel stores and portals for organisations including bricks-and-mortar music stores, mobile telephony operators and ISPs. Some services which initially only offered streaming of tracks now also offer a-la-carte downloads, either through third parties (e.g. Spotify) or fully integrated (Deezer, Juno Digital, Rhapsody etc.). In 2009 "Rolling Stone" reported a price war between iTunes and
Shrouded tidal turbine Shrouded tidal turbine The shrouded tidal turbine is an emerging tidal stream technology that has a turbine enclosed in a venturi shaped shroud or duct (ventuduct), producing a sub atmosphere of low pressure behind the turbine. The venturi shrouded turbine is not subject to the Betz limit and allows the turbine to operate at higher efficiencies than the turbine alone by increasing the volume of the flow over the turbine. Claimed improvements vary, from 1.15 to 4 times higher power output than the same turbine minus the shroud. The Betz limit of 59.3% conversion efficiency for a turbine in an