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Scientists have devised a way to determine roughly where a person has lived using a strand(缕) of hair , a technique that could help track the movements of criminal suspects or unidentified murder victims .

科学家们已经设计出了一种利用人的一缕头发头发估计其住处的方法，这种技术有助于追踪犯罪嫌疑人或者身份不明的谋杀受害者的动向。

The method relies on measuring how chemical variations in drinking water show up in people’s hair.

该方法利用的是测量人们的头发中所显示的饮用水的化学成分差异。

“You’re what you eat and drink, and that’s recorded in you hair,” said Thure Cerling, a geologist at the University of Utah.

“你就是你吃的喝的东西，在你的毛发中都有记录”犹他州地质学家托尔-瑟林说。

While U.S diet is relatively identical, water supplies vary.

美国人的饮食比较类似，但是水源的供应差异较大。

The differences result from weather patterns.

这种差异是气候模式导致的。

The chemical composition of rainfall changes slightly as raid clouds move.

随着雨云的移动，雨水的化学成分也有稍许的变化。

Most hydrogen and oxygen atoms in water are stable , but traces of both elements are also present as heavier isotopes (同位素) .

水中的大部分氢原子和氧原子处于稳定的状态，但是两种元素的轨迹都以质量更重的同位素形式存在，较重的雨先落下。

The heaviest raid falls first .As a result, storms that form over the Pacific deliver heavier water to California than to Utah.

结果，来自于太平洋的暴风雨会给加州带来比犹他州质量更重的水。

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.

相似的模式在全美都存在。通过测量一缕头发中较重的氢氧同位素的比例，科学家们可以构建一个地理学的时间轴。

Each inch of hair corresponds to about two months.

每一英寸的头发对应大概两个月的时间。

Cerling’s team collected tap water samples from 600 cities and constructed a mop of the regional differences.

瑟林的团队手机了来自600个城市的自来水样本，构建了区域间差异的地图。

They checked the accuracy of the map by testing 200 hair samples collected from 65 barber shops.

他妈呢从65家理发店中收集了200份头发样品，用以测试该地图的准确性。

They were able to accurately place the hair samples in broad regions roughly corresponding to the movement of raid systems.

他们能够准确地把头发的样本定位到降雨体系的移动粗略相对应的大区

“It’s not good for pinpointing (精确定位),” Cerling said . “It’s good for eliminating many possibilities.”

“这种方法对于精确定位不一定有效”瑟林说“但可以排除很多可能性”

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.

地方探员托德帕克说，这种方法帮他获得了一名身份不明的妇女的信息，该妇女的骸骨在大盐湖附近被发现。

The woman was 5 feet tall. Police recovered 26 bones, a T-shirt and several strands of hair.

这名妇女有五英寸高。警察发现了26块骨头，一件衬衫和几缕头发。

When Park heard about the research, he gave the hair samples to the researchers.

当帕听说了该项研究之后，他把头发的样本交给了研究者。

Chemical testing showed that over the two years before her death, she moved about every two months.

化学测试表明，在她死前的两年，她每两个月就会搬一次家。

She stayed in the Northwest, although the test could not be more specific than somewhere between eastern Oregon and western Wyoming.

她曾经在西北待过，测试指出具体的地点是在俄勒冈州和怀俄明州西部之间的某地，但无法更精确了。

“It’s still a substantial area,” Park said “But it narrows it way down for me.”

“这仍然是片很大的区域”，帕克说，“但这种方法已经为我缩小了范围。