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SAN FRANCISCO Femme Nike Air VaporMax 97 Beige Blanche Pas Cher , June 8 (Xinhua) -- A new study by University of Washington (UW) transportation engineers indicates that delivering packages with drones can reduce carbon dioxide emissions in certain circumstances as compared to truck deliveries.

A paper published in the July issue of Transportation Research Part D suggests that drones tend to have carbon dioxide emissions advantages over trucks when the drones don't have to fly very far to their destinations or when a delivery route has few recipients, and they compete especially well for small, light packages, such as a bottle of medicine or a kid's bathing suit.

However, the carbon benefits erode as the weight of a package increases, since unmanned aerial vehicles have to use additional energy to stay aloft with a heavy load.

"Flight is so much more energy-intensive -- getting yourself airborne takes a huge amount of effort. So I initially thought there was no way drones could compete with trucks on carbon dioxide emissions Homme Nike Air Max 97 VaporMax Beige Blanche Pas Cher ," Anne Goodchild, a UW associate professor of civil and environmental engineering, was quoted as saying in a news release. "In the end, I was amazed at how energy-efficient drones are in some contexts."

The study compares carbon dioxide emissions and vehicle miles traveled from drone and truck deliveries in 10 different, real-world scenarios in Los Angeles, Southern California. The researchers relied on models for estimating truck data that were previously used in comparing the environmental footprint of grocery delivery services to personal shopping trips. They assumed that drones could carry only one package at a time and would return to a depot after each delivery Homme Nike Air VaporMax 97 Japan Noir Vert Pas Cher , requiring far more back-and-forth and vehicle miles traveled than for an equivalent truck route.

Goodchild noted that it's unlikely that drones will be used for all delivery applications but that there are some contexts in which they appear to make sense, such as shorter trips in less densely developed communities, or in controlled places like a military base or campus.

"Given what we found, probably the most realistic scenario is for drones doing the last leg of the delivery," she said about the possibility of a hybrid system, in which a truck hauls an entire load of packages to a centralized location Nike Air Max 97 Femme Pas Cher , and then a fleet of drones fans out in opposite directions to reach individual homes or businesses.

by Njoroge Kaburo

NAIROBI, June 20 (Xinhua) -- The UN Children's Fund said Tuesday it requires 13.6 million U.S. dollars to respond to the new influx of South Sudanese refugees in the Gambella Region of Ethiopia, and another 7.3 million dollars in Kenya.

In a statement issued to mark the World Refugee Day, UNICEF called on the governments to adopt its six-point agenda for action to protect refugee and migrant children and ensure their well-being.

Leila Pakkala, UNICEF's Regional Director for Eastern and Southern Africa, said more than 1 million children have been forced from their homes in South Sudan Nike Air Max 97 Homme Pas Cher , often amid horrific violence.

"Day after day, week after week, they are being received by countries such as Uganda, Ethiopia and Kenya. Despite great efforts on many fronts, the systems in these countries are tremendously stretched," Pakkala said.

According to the UN Nike Air Max 97 Rouge Pas Cher , more than 1.8 million people have crossed into neighboring countries since violence erupted in South Sudan in December 2013.

In just one year the population of refugees in Uganda has more than doubled from 500,000 to more than 1.25 million, making Uganda now a major host to the fastest growing refugee emergency in the world.

The UN says more than 1,000 children continue to flee South Sudan on average every day in search of safety, making the region's refugee crisis a children's crisis.

The UNICEF noted that 86 percent of all refugees in Uganda are women and children.

"Uganda is now Africa's leading refugee-hosting country, having jumped from the eighth largest refugee-hosting country in the world in mid-2016 to the third largest today Nike Air Max 97 Argent Pas Cher , after Turkey and Pakistan," it said.

Such dramatic numbers are placing excessive pressure on the receiver nation and host community resources, especially social services that are critical to children's well-being.

Pakkala praised the progressive and generous open door policy to refugees by the Ugandan government.

"This approach provides better prospects for refugee children in Uganda than in many contexts globally. The very real hope is that such a model is supported widely across countries," she added.

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Venus Williams captured her 47th WTA career title on Saturday, and her biggest in five years, when she won the Wuhan Open in China Nike Air Max 97 Noir Pas Cher , beating Wimbledon runner-up Garbine Muguruza.

The 35-year-old American was leading Muguruza 6-3 3-0 when the Spaniard, struggling with injury, retired, handing the title to Williams, who was already well on top and had won the last five games in a row.

A sympathetic Williams consoled Muguruza, one of the best young players in the game who had a tough semi-final with Germany's Angelique Kerber Nike Air Max 97 Blanche Pas Cher , during the victory presentation.

"Congratulations Garbine for making the final," Williams said. "I know you had a tough match yesterday - it's not easy when you don't play your best, and I probably didn't have a chance if you felt well!"

Muguruza traded blows with Williams through most of t.