Within the past ten years, the amount of social networking sites available to the public has greatly increased as well as the number of adolescents using them. Several sources report a high proportion of adolescents who use social media: 73% of 1217 year olds reported having at least one social networking profile; two-thirds (68%) of teens text every day, half (51%) visit social networking sites daily, and 11% send or receive tweets at least once every day. In fact, more than a third (34%) of teens visit their main social networking site several times a day. One in four (23%) teens are "heavy" social media users, meaning they use at least two different types of social media each and every day.
In recent years, has the amount of social networking sites available to the public increased or decreased?
greatly increased

There is evidence of induced copper deficiency in those taking 100300 mg of zinc daily. A 2007 trial observed that elderly men taking 80 mg daily were hospitalized for urinary complications more often than those taking a placebo. The USDA RDA is 11 and 8 mg Zn/day for men and women, respectively. Levels of 100300 mg may interfere with the utilization of copper and iron or adversely affect cholesterol. Levels of zinc in excess of 500 ppm in soil interfere with the ability of plants to absorb other essential metals, such as iron and manganese. There is also a condition called the zinc shakes or "zinc chills" that can be induced by the inhalation of freshly formed zinc oxide formed during the welding of galvanized materials. Zinc is a common ingredient of denture cream which may contain between 17 and 38 mg of zinc per gram. There have been claims of disability, and even death, due to excessive use of these products.
What kind of complications were seen in men taking 80mg zinc a day?
urinary

Around 10,200 BC the first fully developed Neolithic cultures belonging to the phase Pre-Pottery Neolithic A (PPNA) appeared in the fertile crescent. Around 10,700 to 9,400 BC a settlement was established in Tell Qaramel, 10 miles north of Aleppo. The settlement included 2 temples dating back to 9,650. Around 9000 BC during the PPNA, one of the world's first towns, Jericho, appeared in the Levant. It was surrounded by a stone and marble wall and contained a population of 20003000 people and a massive stone tower. Around 6,400 BC the Halaf culture appeared in Lebanon, Israel and Palestine, Syria, Anatolia, and Northern Mesopotamia and subsisted on dryland agriculture.
When did the Pre-Pottery Neolithic A (PPNA) phase start?
Around 10,200 BC