The method relies on measuring how chemical variations in drinking water show up in people’s hair.
“You’re what you eat and drink, and that’s recorded in your hair,” said Thure Cerling, a geologist at the University of Utah.
While U.S diet is relatively identical, water supplies vary. The differences result from weather patterns. The chemical composition of rainfall changes slightly as rain clouds move.
Most hydrogen and oxygen atoms in water are stable, but traces of both elements are also present as heavier isotopes (同位素). The heaviest rain falls first. As a result, storms that form over the Pacific deliver heavier water to California than to Utah.
Similar patterns exist throughout the U.S. By measuring the proportion of heavier hydrogen and oxygen isotopes along a strand of hair, scientists can construct a geographic timeline. Each inch of hair corresponds to about two months.
Cerling’s team collected tap water samples from 600 cities and constructed a map of the regional differences. They checked the accuracy of the map by testing 200 hair samples collected from 65 barber shops. They were able to accurately place the hair samples in broad regions roughly corresponding to the movement of rain systems.
“It’s not good for pinpointing(精确定位),” Cerling said. “It’s good for eliminating many possibilities.”
Todd Park, a local detective, said the method has helped him learn more about an unidentified woman whose skeleton was found near Great Salt Lake.
The woman was 5 feet tall. Police recovered 26 bones, a T-shirt and several strands of hair.
When Park heard about the research, he gave the hair samples to the researchers.
Chemical testing showed that over the two years before her death, she moved about every two months.
She stayed in the Northwest, although the test could not be more specific than somewhere between eastern Oregon and western Wyoming.
“It’s still a substantial area,” Park said “But it narrows it way down for me.”
1. What is the scientists’ new discovery?
| A．One’s hair growth has to do with the amount of water they drink. |
| B．A person’s hair may reveal where they have lived. |
| C．Hair analysis accurately identifies criminal suspects. |
| D．The chemical composition of hair varies from person to person. |
| A．Food and drink affect one’s personality development. |
| B．Food and drink preferences vary with individuals. |
| C．Food and drink leave traces in one’s body tissues. |
| D．Food and drink are essential to one’s existence. |
| A．A map showing the regional differences of tap water. |
| B．A collection of hair samples from various barber shops. |
| C．A method to measure the amount of water in human hair. |
| D．A chart illustrating the movement of the rain system. |
| A．It helps analyze the quality of water in different regions. |
| B．It helps the police determine where a crime is committed. |
| C．It helps the police narrow down possibilities in detective work. |
| D．It helps identify the drinking habits of the person under investigation. |
相似题推荐
【推荐1】This fall, students can monitor occupancy rates in Pearl Campus Library（PCL）spaces through the Waitz App that shows how busy the library is in real time without having to physically visit it themselves.
“Waitz shows how busy each floor of the library is before they leave their dorm or house,” Mandy, Social Media Manager of Waitz’s parent company Occuspace, said. “Now, students never have to waste time pacing the halls of libraries looking for an open seat again.”
“The beauty of Waitz lies in helping anyone who’s walked into one of our popular spaces, only to discover that they can’t find a space,” Maurini, a director of the university said. “Using the app or looking at one of the dashboards, they can identify their best bets for an alternative space—and, in the ideal scene, to know before they go to the library where’s the best place to find a spot.”
Occuspace employs the Internet of Things to determine how many people are in a given space. They installed sensors into the walls of PCL spaces that scan for Bluetooth and Wi-Fi signals. The signals are then changed into live occupancy data which are displayed in the monitors within PCL and on the mobile app. According to Occuspace CEO Nic Stephenson, the sensors have at least a 90% accuracy rate and do not collect any personally identifiable information. The algorithm（算法）also takes into account the number of devices an average student uses when calculating the occupancy rate of a space.
Stephenson launched Occuspace in 2017 with his roommates after being frustrated by the lack of open spaces at the University’s library. “I was walking up and down the eight floors trying to find a seat to study one night only to see zero spaces available,” Stephenson said. “I literally said to myself out loud, ‘I wish I knew how busy every floor was before I came!’ That’s when Occuspace was born.”
1. What can students do with the Waitz App?| A．Visit the library online. | B．Save time when finding books. |
| C．See seats available in the library. | D．Learn how busy students in the library are. |
| A．The signals can be transformed instantly. |
| B．The sensors can be shown on the mobile app. |
| C．The algorithm considers the number of students. |
| D．The users’ identifiable information is kept secret. |
| A．His roommates’ encouragement. |
| B．His unpleasant experience at the library. |
| C．His intention of improving learning efficiency. |
| D．His hope of seeking an empty space at the university. |
| A．Stephenson develops an app for a library. |
| B．An Algorithm calculates the number of seats. |
| C．Occuspace collects accurate personal information. |
| D．Waitz helps students know occupancy of library spaces. |
【推荐2】Mystery of Evolution
Following the outbreak of the novel coronavirus pneumonia(NCP), also named COVID-19 by WHO, there is a general fear of the unknown virus as its full effects remain to be seen. Fever, coughing, sore throat, difficulty breathing-the NCP's symptoms are similar to the common cold or the flu. but it's potentially more dangerous.
Viruses could be deadly, like HIV and Ebola (埃博拉) . But what are viruses? How can they cause so much trouble? Viruses are non-living organisms (有机体) approximately one-millionth of an inch long. Unlike human cells or bacteria, they can't reproduce on their own.
Viruses can infect every living thing-from plants and animals down to the smallest bacteria. For this reason, they always have the potential to be dangerous to human life. Sometimes a virus can cause a disease so serious that it is fatal. Other viral infections cause no noticeable reaction. Viruses lie around our environment all of the time, waiting for a host cell to come along. They can eater our bodies by the nose, mouth, eyes or breaks in the skin.
But the basic question is, where did viruses first come from?
For the time being, these are only theories. The technology and evidence we have today cannot be used to test these theories and identify the most plausible explanation.
| A．Once inside, they try to find a host cell to infect. |
| B．Until now, no clear explanation for their origin exists. |
| C．Continuing studies may provide us with clearer answers. |
| D．There's pretty strong evidence that this is a bat origin coronavirus. |
| E．However, there are three main hypotheses (假说) to explain the origin of viruses. |
| F．Instead, they invade the cells of living organisms to reproduce, spread and take over. |
| G．Bat is a flying mammal with a long lifespan, whose temperature is high, similar to a fever. |
【推荐3】A 1.6-metre-tall robot may soon become the best friend for lonely elderly people, as Chinese scientists are making the final sprint (冲刺) towards its market launch (投放), said a senior researcher on the robot project on Saturday.
“We are working on testing the exact functions and ways to reduce the cost in preparations for an expected market launch of the robot in two to three years,” said Li Ruifeng, a member of the project.
He said the team hoped to reduce the cost so that the robot can be priced at 30, 000 to 50, 000 yuan, which is expected to be an affordable price for most of China’s better-off families.
The robot has been developed with the functions of fetching food and medicine, sounding alarms in case of water or gas leakage, sending texts or video images via wireless communications, and even singing a song or playing chess to entertain its masters.
Li said that the robot, developed independently in China, has technology at the same level as those in Western labs.
China set about the research of the robot in 2007, when it was listed as a national key project. It is backed by government funding. China has the world’s largest elderly population with 159 million people over 60, accounting for 12 percent of its total population. According to a survey by the Ministry of Civil Affairs, more than 10 million caregivers and nurses are needed to attend the elderly, as most of Chinese elderly prefer to live their retired lives at home.
1. The underlined word “backed” in the last paragraph means ________.| A．supported | B．suggested | C．controlled | D．stopped |
| A．our government pays no attention to the elderly people |
| B．China has the world’s largest elderly population |
| C．Chinese elderly people prefer to be looked after by robot caregivers |
| D．robots are the best friends for the lonely elderly people |
| A．Robot caregivers will appear in the market in 2 to 3 years. |
| B．Robot caregivers can help elderly people to do everything. |
| C．China needs some technical support from Western labs. |
| D．The robot is expected to be bought by every person. |
| A．advertise a robot caregiver to the elderly |
| B．tell Chinese elderly not to worry about their lives |
| C．explain how robot caregivers work in the future |
| D．introduce a newly-developed robot caregiver |
