QUES: Phosphor-based LED efficiency losses are due to the heat loss from the Stokes shift and also other phosphor-related degradation issues. Their luminous efficacies compared to normal LEDs depend on the spectral distribution of the resultant light output and the original wavelength of the LED itself. For example, the luminous efficacy of a typical YAG yellow phosphor based white LED ranges from 3 to 5 times the luminous efficacy of the original blue LED because of the human eye's greater sensitivity to yellow than to blue (as modeled in the luminosity function). Due to the simplicity of manufacturing the phosphor method is still the most popular method for making high-intensity white LEDs. The design and production of a light source or light fixture using a monochrome emitter with phosphor conversion is simpler and cheaper than a complex RGB system, and the majority of high-intensity white LEDs presently on the market are manufactured using phosphor light conversion.
Why is efficiency sometimes lost in phosphor-based LEDs?

ANS: heat loss from the Stokes shift

QUES: IBM has been a leading proponent of the Open Source Initiative, and began supporting Linux in 1998. The company invests billions of dollars in services and software based on Linux through the IBM Linux Technology Center, which includes over 300 Linux kernel developers. IBM has also released code under different open source licenses, such as the platform-independent software framework Eclipse (worth approximately US$40 million at the time of the donation), the three-sentence International Components for Unicode (ICU) license, and the Java-based relational database management system (RDBMS) Apache Derby. IBM's open source involvement has not been trouble-free, however (see SCO v. IBM).
What initiative was created by IBM in 1998?

ANS: unanswerable

QUES: Nigeria was ranked 30th in the world in terms of GDP (PPP) in 2012. Nigeria is the United States' largest trading partner in sub-Saharan Africa and supplies a fifth of its oil (11% of oil imports). It has the seventh-largest trade surplus with the US of any country worldwide. Nigeria is the 50th-largest export market for US goods and the 14th-largest exporter of goods to the US. The United States is the country's largest foreign investor. The International Monetary Fund (IMF) projected economic growth of 9% in 2008 and 8.3% in 2009. The IMF further projects an 8% growth in the Nigerian economy in 2011.
How much of the US's oil imports come from Nigeria?

ANS: 11%

QUES: Korea was ruled by Japan from 1910 until the closing days of World War II. In August 1945, the Soviet Union declared war on Japan and—by agreement with the United States—occupied Korea north of the 38th parallel. U.S. forces subsequently occupied the south and Japan surrendered. By 1948, two separate governments had been set up. Both governments claimed to be the legitimate government of Korea, and neither side accepted the border as permanent. The conflict escalated into open warfare when North Korean forces—supported by the Soviet Union and China—invaded South Korea on 25 June 1950. On that day, the United Nations Security Council recognized this North Korean act as invasion and called for an immediate ceasefire. On 27 June, the Security Council adopted S/RES/83: Complaint of aggression upon the Republic of Korea and decided the formation and dispatch of the UN Forces in Korea. Twenty-one countries of the United Nations eventually contributed to the defense of South Korea, with the United States providing 88% of the UN's military personnel.
How many countries assisted in the defense of South Korea?

ANS:
Twenty-one