Here is a question about this article: In 1940, non-Hispanic whites constituted 86.8% of the city's population. The population peaked at more than two million residents in 1950, then began to decline with the restructuring of industry, which led to the loss of many middle-class union jobs. In addition, suburbanization had been drawing off many of the wealthier residents to outlying railroad commuting towns and newer housing. Revitalization and gentrification of neighborhoods began in the late 1970s and continues into the 21st century, with much of the development in the Center City and University City areas of the city. After many of the old manufacturers and businesses left Philadelphia or shut down, the city started attracting service businesses and began to more aggressively market itself as a tourist destination. Glass-and-granite skyscrapers were built in Center City. Historic areas such as Independence National Historical Park located in Old City and Society Hill were renovated during the reformist mayoral era of the 1950s through the 1980s. They are now among the most desirable living areas of Center City. This has slowed the city's 40-year population decline after it lost nearly one-quarter of its population.
What is the answer to this question: When was the peak of Philadelphia's population?
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So... 1950

Here is a question about this article: A 2001 study by Nebel et al. showed that both Ashkenazi and Sephardic Jewish populations share the same overall paternal Near Eastern ancestries. In comparison with data available from other relevant populations in the region, Jews were found to be more closely related to groups in the north of the Fertile Crescent. The authors also report on Eu 19 (R1a) chromosomes, which are very frequent in Central and Eastern Europeans (54%60%) at elevated frequency (12.7%) in Ashkenazi Jews. They hypothesized that the differences among Ashkenazim Jews could reflect low-level gene flow from surrounding European populations and/or genetic drift during isolation. A later 2005 study by Nebel et al., found a similar level of 11.5% of male Ashkenazim belonging to R1a1a (M17+), the dominant Y-chromosome haplogroup in Central and Eastern Europeans.
What is the answer to this question: A 2001 study by Nebel et al. showed that which two populations share the same overall paternal Near Eastern ancestries?
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So... Ashkenazi and Sephardic Jewish populations

Here is a question about this article: From the mid-1950s through the 1960s, in the U.S. the common home record player or "stereo" (after the introduction of stereo recording) would typically have had these features: a three- or four-speed player (78, 45, 33 13, and sometimes 16 23 rpm); with changer, a tall spindle that would hold several records and automatically drop a new record on top of the previous one when it had finished playing, a combination cartridge with both 78 and microgroove styli and a way to flip between the two; and some kind of adapter for playing the 45s with their larger center hole. The adapter could be a small solid circle that fit onto the bottom of the spindle (meaning only one 45 could be played at a time) or a larger adaptor that fit over the entire spindle, permitting a stack of 45s to be played.
What is the answer to this question: What feature of 45s required an adapter in most home stereos?
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So...
larger center hole.