Article: Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. LEDs are used as motion sensors, for example in optical computer mice. The Nintendo Wii's sensor bar uses infrared LEDs. Pulse oximeters use them for measuring oxygen saturation. Some flatbed scanners use arrays of RGB LEDs rather than the typical cold-cathode fluorescent lamp as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light. Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a touchscreen that registers reflected light from a finger or stylus. Many materials and biological systems are sensitive to, or dependent on, light. Grow lights use LEDs to increase photosynthesis in plants, and bacteria and viruses can be removed from water and other substances using UV LEDs for sterilization.

Question: What device uses infrared LEDs to measure oxygen saturation?
Ans: Pulse oximeters

Here is a question about this article: Madonna holds the record for the most number-ones on all combined Billboard charts, including twelve number-one songs on the Billboard Hot 100 and eight number-one albums on the Billboard 200. With 45 songs topping the Hot Dance Club Songs chart, Madonna became the artist with the most number-one songs on an active Billboard chart, pulling ahead of George Strait with 44 number-one songs on the Hot Country Songs chart. She has also scored 38 top-ten singles on the Hot 100, more than any other artist in history. In 2008, Billboard magazine ranked her at number two, behind The Beatles, on the Billboard Hot 100 All-Time Top Artists, making her the most successful solo artist in the history of American singles chart.
What is the answer to this question: Who is the most successful solo artist in the history of American singles chart?
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So... Madonna

The problem: Answer a question about this article:
In 1936, Wever was killed in an air crash. The failure to implement his vision for the new Luftwaffe was largely attributable to his immediate successors. Ex-Army personnel Albert Kesselring and Hans-Jurgen Stumpff are usually blamed for the turning away from strategic planning and focusing on close air support. However, it would seem the two most prominent enthusiasts for the focus on ground-support operations (direct or indirect) were actually Hugo Sperrle and Hans Jeschonnek. These men were long-time professional airmen involved in German air services since early in their careers. The Luftwaffe was not pressured into ground support operations because of pressure from the army, or because it was led by ex-army personnel. It was instead a mission that suited the Luftwaffe's existing approach to warfare; a culture of joint inter-service operations, rather than independent strategic air campaigns.
What two men were the most important in ground support?
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The answer: Hugo Sperrle and Hans Jeschonnek

Problem: Please answer a question about the following article about Frederic Chopin:
During the summers at Nohant, particularly in the years 183943, Chopin found quiet, productive days during which he composed many works, including his Polonaise in A-flat major, Op. 53. Among the visitors to Nohant were Delacroix and the mezzo-soprano Pauline Viardot, whom Chopin had advised on piano technique and composition. Delacroix gives an account of staying at Nohant in a letter of 7 June 1842:
Who were two visitors to Chopin while in Nohant?
A: Delacroix and the mezzo-soprano Pauline Viardot

Question: Read this and answer the question

Paul VI did renounce many traditional symbols of the papacy and the Catholic Church; some of his changes to the papal dress were reversed by Pope Benedict XVI in the early 21st century. Refusing a Vatican army of colourful military uniforms from centuries, he got rid of them. He became the first pope to visit five continents. Paul VI systematically continued and completed the efforts of his predecessors, to turn the Euro-centric Church into a Church of the world, by integrating the bishops from all continents in its government and in the Synods which he convened. His 6 August 1967 motu proprio Pro Comperto Sane opened the Roman Curia to the bishops of the world. Until then, only Cardinals could be leading members of the Curia.

What papal statement under Paul VI opened the Vatican doors to global influences?
Answer: motu proprio Pro Comperto Sane

To Popper, who was an anti-justificationist, traditional philosophy is misled by the false principle of sufficient reason. He thinks that no assumption can ever be or needs ever to be justified, so a lack of justification is not a justification for doubt. Instead, theories should be tested and scrutinised. It is not the goal to bless theories with claims of certainty or justification, but to eliminate errors in them. He writes, "there are no such things as good positive reasons; nor do we need such things [...] But [philosophers] obviously cannot quite bring [themselves] to believe that this is my opinion, let alone that it is right" (The Philosophy of Karl Popper, p. 1043)
What don't we need to look for about theories in Popper's view?
good positive reasons