Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

In this July 9, 2016 file photo, girls jump from a diving platform into the Geneva Lake and enjoy sunny and warm weather, in Villeneuve, Switzerland. After nearly 90 years, women can legally swim topless in Geneva’s lake and Rhone River without running the risk of a fine. Geneva’s regional council has voted to modify a 1929 ordinance that banned women from swimming topless in the city’s main natural waterways, though the change doesn’t apply to public swimming pools or swimming totally naked. Nicolas Bolle, an official with Geneva’s security department, on Thursday, April 6, 2017 confirmed the council’s action a day earlier. (Photo by Jean-Christophe Bott/Keystone via AP Photo)

In this April 20, 2017 photo, a woman is aided by fellow demonstrators after falling, overcome by tear gas, during anti-government protests in Caracas, Venezuela. Tens of thousands of protesters asking for the resignation of President Nicolas Maduro flooded the streets again, one day after three people were killed and hundreds arrested in the biggest anti-government demonstrations in years. (Photo by Ariana Cubillos/AP Photo)

A person poses on the track during a fashion competition at the Durban July horse racing event in Durban, South Africa July 1, 2017. (Photo by Rogan Ward/Reuters)

An Iraqi woman and foreigners use pair of compact discs as a filter to watch the partial solar eclipse in war-torn Baghdad, 29 March 2006. Without access to proper equipment to protect their eyes from the sun's rays, eclipse watchers in Iraq used makeshift filters. The moon blotted out the sun over northwest Africa early Wednesday, turning day into night in a total solar eclipse as it swept a shadowy path from the outer tip of Brazil to the steppes of Mongolia. (Photo by Hassan Ammar/AFP Photo)

Young revelers take part in a parade called "La Calabiuza" on November 1, 2015, on the eve of the Day of the Dead in Tonacatepeque, 20 kms (13 miles) north of San Salvador. During the celebration, the residents of Tonacatepeque, originally an indigenous community, recall the characters from the mythology of Cuscatlan – pre-Columbian west and central regions of El Salvador – and their dead relatives. (Photo by Marvin Recinos/AFP Photo)

A bride gets her make-up done before the start of a mass marriage ceremony in Kolkata, India, February 14, 2016. A total of 150 tribal Hindu, Muslim and Christian couples from various villages across the state took their wedding vows on Sunday during the day-long mass marriage ceremony organised by a social organisation, the organisers said. (Photo by Rupak De Chowdhuri/Reuters)

Marieke van der Meer from the Netherlands works on her sculpture “Flora” at the sand sculpture show in Binz on Ruegen island, Germany, 09 March 2016. With the motto “Fascination Nature”, 50 sand artists have created oversized sculptures. The sculptors use 16,000 tons of special sand that is pressed into big blocks first and then formed. The 7th sand sculpture show on 5,600 square meters of exhibition ground opens on 12 March 2016. (Photo by Ens Buettner/EPA)