Two students were shot and suffered non-life-threatening wounds outside a gym during a basketball game at Frederick High School in Maryland on Wednesday evening adidas superstar black gold stripes , local police and the school district said.
All other students and staff were safe and the two injured students were receiving care, Frederick County Public Schools said in a tweet.
The building was cleared and police were searching for suspects in the incident, said a spokesman for police in Frederick, about 50 miles northwest of Washington.
CANBERRA, April 12 (Xinhua) -- The 2008 Beijing Olympic pole vault champion Steve Hooker of Australia announced his retirement from the sport on Friday.
The 31-year-old said he is still physically fit but doesn't have the mental drive to continue at the top.
"I honestly thought the body would be the one that would give way, and that would be the end ... but it has almost been the opposite," said Hooker.
From 2008 to 2010 adidas superstar white gold stripes , he won every major title in his event, the Olympics, world indoors and outdoors championships. But Hooker had difficulty qualifying for the 2012 Olympics due to what he often called the pole vaulting "yips," and did not make the London final.
By Yu Fei and Li Mengxin
BEIJING, Oct. 30 (Xinhua) -- There's a giant "ruler" hidden among millions of galaxies in the universe. With it, scientists can measure how fast the universe is expanding. This will help them explore dark energy, the mysterious power behind cosmic expansion adidas ultra boost parley icey blue , and so speculate on the universe's destiny.
With this ruler, Chinese astronomers recently succeeded in reconstructing the evolution history of dark energy based on the observation of over a million galaxies. The research shows that dark energy is dynamic.
"What it means is that dark energy, which causes cosmic expansion, might not be a vacuum energy with a constant density, like many scientists previously believed, but rather an energy field with certain dynamic properties," said Zhao Gongbo ultra boost 3.0 triple black for sale , a researcher at the National Astronomical Observatories of the Chinese Academy of Sciences (CAS).
The research result made by a team led by Zhao was recently published on the academic journal, Nature Astronomy.
Dark energy determines the universe's destiny, he said.
"If dark energy is indeed a vacuum energy, the universe will keep on expanding until it ends with a 'big rip'. But if dark energy is dynamic, the universe might go through expansion, contraction and then expansion again -- a cyclical universe."
FINDING THE RULER
How do scientists measure such a vast universe? According to Zhao, nature provides a magic ruler -- baryon acoustic oscillations.
The early universe consisted of a hot ultra boost uncaged for sale , dense plasma of electrons, baryons (protons and neutrons) and photons, like a pot of porridge. The primordial disturbances from cosmic creation transmitted through the "porridge," causing periodic changes to its density, temperature and pressure on the chronological sequence. This transmission mechanism is similar to sound waves transmission, so it is called baryon acoustic oscillations (BAO) by scientists.
About 380,000 years after the Big Bang oxford tan yeezy for sale , the cooled-down universe became transparent. The transmission of BAOs stopped, and the information of those oscillations is frozen in space-time. But the great power of it influenced the distribution of galaxies in the universe.
In 2005, the BAO signal was discovered for the first time. Thus cosmologists finally got the "standard ruler" they dreamed of, in order to measure the universe -- whether it's flat or curved, and how fast it's expanding.
But that's just the start. Scientists also have to make accurate measurements.
Since 2012, Zhao's team has been making observations with the Sloan telescope at the Apache Point Observatory in the U.S. state of New Mexico. Based on the observation of galaxies and quasars, they obtained high-precision BAO signals.
"The observation of BAOs is becoming more precise. Previous observations focused on a short period of the universe yeezy boost 350 moonrock online , but we adopted a new method. Like doing a CT scan for a more remote universe, we get to know more about the history of cosmic evolution," said Zhao.
Based on the measurement with the ruler, astronomers will be able to draft a three-dimensional map of the universe.
EXPLORING DARK ENERGY
In 1929, U.S. astronomer Edwin Powell Hubble discovered most galaxies are moving away from the Earth, indicating the universe is expanding. The discovery shocked the world, overthrowing the long-held perception of a static universe.
But many scientists still believed that cosmic expansion would slow down. However yeezy boost 350 turtle dove for sale , to their surprise, two research teams, in the United States and Australia, reported respectively in 1998 that they had discovered cosmic expansion is speeding up.
Scientists assumed an unknown power they called dark energy was accelerating cosmic expansion. Even now, scientists still know little about it, although they have put forward many theoretical models.
For instance, a model of dark energy advanced by Zhang Xinmin yeezy boost 350 pirate black for sale , a researcher at Institute of High Energy Physics under the CAS, conforms to the observation results of Zhao's team using the Sloan telescope.
In order to test so many theories, large-scale computer simulations are needed. "With the help of China's Tianhe supercomputer as well as foreign supercomputers, we simulated approximately 2,000 universes for analytic purposes," said Zhao.
On the computer screen, billions of years flew by yeezy boost 350 v2 for sale , galaxies took shape and the universe evolved.
"I want to understand why cosmic expansion is accelerating," said Zhao. "There is so much new physics in that. Normal matter only accounts for about 5 percent of the universe, while the other 95 percent of dark matter and dark energy is still unknown to us. If one day we know what dark energy is, the whole discipli.