QUES: By the late 1990s, blue LEDs became widely available. They have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By varying the relative In/Ga fraction in the InGaN quantum wells, the light emission can in theory be varied from violet to amber. Aluminium gallium nitride (AlGaN) of varying Al/Ga fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of InGaN/GaN blue/green devices. If un-alloyed GaN is used in this case to form the active quantum well layers, the device will emit near-ultraviolet light with a peak wavelength centred around 365 nm. Green LEDs manufactured from the InGaN/GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems, but practical devices still exhibit efficiency too low for high-brightness applications.[citation needed]

What are cladding layers?
What is the answer?
ANS: active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN
QUES: Originally, the hardware architecture was so closely tied to the Mac OS operating system that it was impossible to boot an alternative operating system. The most common workaround, is to boot into Mac OS and then to hand over control to a Mac OS-based bootloader application. Used even by Apple for A/UX and MkLinux, this technique is no longer necessary since the introduction of Open Firmware-based PCI Macs, though it was formerly used for convenience on many Old World ROM systems due to bugs in the firmware implementation.[citation needed] Now, Mac hardware boots directly from Open Firmware in most PowerPC-based Macs or EFI in all Intel-based Macs.

What was introduced that made using Mac OP alternative operating systems easier?
What is the answer?
ANS: unanswerable
QUES: On September 27, 2006 Schwarzenegger signed a bill creating the nation's first cap on greenhouse gas emissions. The law set new regulations on the amount of emissions utilities, refineries and manufacturing plants are allowed to release into the atmosphere. Schwarzenegger also signed a second global warming bill that prohibits large utilities and corporations in California from making long-term contracts with suppliers who do not meet the state's greenhouse gas emission standards. The two bills are part of a plan to reduce California's emissions by 25 percent to 1990s levels by 2020. In 2005, Schwarzenegger issued an executive order calling to reduce greenhouse gases to 80 percent below 1990 levels by 2050.

The regulations pertain to emissions from utilities, manufacturing plants, and what other entity?
What is the answer?
ANS:
refineries