Riot police officers in position to crack down on demonstrators during a protest against Venezuelan President Nicolas Maduro, in Caracas on April 20, 2017. Venezuelan riot police fired tear gas Thursday at groups of protesters seeking to oust President Nicolas Maduro, who have vowed new mass marches after a day of deadly unrest. Police in western Caracas broke up scores of opposition protesters trying to join a larger march, though there was no immediate repeat of Wednesday's violent clashes, which left three people dead. (Photo by Juan Barreto/AFP Photo)

Negin Ekhpulwak, leader of the Zohra orchestra, an ensemble of 35 women, practises on a piano at Afghanistan's National Institute of Music, in Kabul, Afghanistan April 9, 2016. Playing instruments was banned under Taliban rule in Afghanistan, and even today, many conservative Muslims frown on most forms of music. Living in an orphanage in the capital, Kabul, 19-year-old Negin Ikhpolwak leads an ensemble of 35 women that plays both Western and Afghan musical instruments. In a country notorious internationally for harsh restrictions on women in most areas of life, Negin's story highlights a double challenge. (Photo by Ahmad Masood/Reuters)

Migrants with a stick, stones and knife fight with each other after a brawl erupted over a place in an overcrowded train heading to the Serbian border at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 14 August 2015. (Photo by Georgi Licovski/EPA/EFE)

A couple passes the sculpture “Transformer” by Chinese artist Bi Heng during snowfall in Kassel, central Germany, Tuesday March 12, 2013. Frankfurt airport closed, a quarter of flights out of Paris were canceled, Belgium suffered record traffic jams and high-speed trains were stuck in stations – all because of a sudden dump of oddly late snowfall on Western Europe. Less prepared for the kind of heavy snow that regularly hits northern and eastern neighbors, France, Britain and Belgium struggled Tuesday to keep moving amid the frosty, blustery conditions. (Photo by Uwe Zucchi/AP Photo/Dpa)

A woman learns how to use an AK-47 assault rifle during a civilians self-defence course in the outskirts of Lviv, western Ukraine, on March 4, 2022. The Russian army occupied on March 4, 2022 the Ukrainian nuclear power plant of Zaporozhie (south), the largest in Europe, where bombings in the night have raised fears of a disaster as more than 1.2 million people have fled Ukraine into neighbouring countries since Russia launched its full-scale invasion on February 24, United Nations figures showed on March 4, 2022. (Photo by Daniel Leal/AFP Photo)

Life reconstruction of the new oviraptorosaurian dinosaur species Anzu wyliei in its 66 million-year-old environment in western North America as seen in an undated handout illustration by Mark A. Klinger, Carnegie Museum of Natural History. Some 18,000 species, great and small, were discovered in 2014, adding to the 2 million already known, scientists said on May 21, 2015 as they released a “Top 10” list that highlights the diversity of life. Anzu wyliei, one of the top 10, dubbed “the chicken from hell”, is extinct. The feathered dinosaur whose partial skeletons were unearthed in the Dakotas was a contemporary of T. rex and Triceratops. (Photo by Mark A. Klingler/Reuters/Carnegie Museum of Natural History)

Indonesian residents look at the Mount Sinabung volcano as it spews volcanic ash near the Tiga Pancur village in Karo, North Sumatra on August 3, 2016. Volcanic eruptions in Indonesia in recent days have forced the closure of two airports and disrupted some flights to the holiday island of Bali, officials said August 3. Mount Sinabung, a volcano on the western island of Sumatra which has been rumbling for some time, also erupted violently on August 2, although its ash clouds did not disrupt any flights. (Photo by Y.T. Haryono/AFP Photo)