丽江陕汽SX2190转向及前桥实训台(株洲气体定压比热测定仪) (今日更新中)

 Two 250,000-year-old teeth from two Neanderthal children revealed that both of them were exposed to lead twice during their short lifetimes, the first known case of lead exposure in Neanderthals.An international team of researchers studied the two teeth, as well as one from a modern human child who lived 5,000 years ago. All of them are from the same archaeological site in southeast France. The results of their analysis were published Wednesday in the journal Science Advances."Traditionally, people thought lead exposure occurred in populations only after industrialization, but these results show it happened prehistorically, before lead had been widely released into the environment," said Christine Austin, study co-author and assistant professor in the Department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai. "Our team plans to analyze more teeth from our ancestors and investigate how lead exposures may have affected their health and how that may relate to how our bodies respond to lead today."And as with tree rings, researchers used the teeth to determine key events in the children's lives. During childhood, new teeth layers are formed each day, capturing chemical signatures that can be traced."Teeth record environmental variation based on the climate, even where you're growing up," said Tanya Smith, lead author of the study and associate professor at Griffith University. "That's possible because when you're growing, your teeth you actually lock in a record of the chemistry of the water and the food that you're eating and drinking. Because teeth have these tiny timelines, we can relate the chemistry to the growth to calculate ancient climate records. We can't do that with any other element of the body."They were able to determine that one of the Neanderthal children was born in the spring and that both children were more likely to be sick during the colder winter seasons. They lived through more extreme seasons with a greater variation in temperature than the modern human child who was also studied.The intact teeth had growth rings, which the researchers used to measure barium, lead and oxygen. Lasers targeted tiny spots in the teeth to map their chemistry and reconstruct ancient climate records. This reconstruction was able to map a weekly scale of variation, showing when the summer and winter seasons happened and how long they lasted. The researchers related this back to the individual's growth."This study reports a major breakthrough in the reconstruction of ancient climates, a significant factor in human evolution, as temperature and precipitation cycles influenced the landscapes and food resources our ancestors relied on," Smith said.The growth rings also provided evidence of nursing."We were able to identify milk intake through breastfeeding in one individual based on a trace element called barium," Smith said. "We were able to time that to the season."That individual nursed for 2? years, which is similar to modern human children who lived in hunter-gatherer environments. "This is something we may share in common with Neanderthals," Smith said. Unfortunately, although the Neanderthal child survived infancy, it did not reach adulthood. The ages of the children were not included in the study.The researchers believe that the children were exposed to lead environmentally, either inhaling or ingesting it."That must have come from natural deposits in the area, whether they were going into an underground environment or they were eating contaminated food that was incorporated into their growing bones and teeth," Smith said.Smith believes that this research emphasizes the different levels of information that can be taken from teeth."We've now got the ability to integrate ancient climate data with health history, nursing history and illness," she said. "To be able to get all that information from a single sample 250,000 years ago is a unique opportunity."But this doesn't just apply to studying those who lived before us."Dietary patterns in our early life have far-reaching consequences for our health, and by understanding how breastfeeding evolved, we can help guide the current population on what is good breastfeeding practice," said Manish Arora, study co-author and vice chairman of the Department of Environmental Medicine and Public Health at the Icahn School of Medicine. "Our research team is working on applying these techniques in contemporary populations to study how breastfeeding alters health trajectories including those of neurodevelopment, cardiac health and other high-priority health outcomes." 4648

(AP) -- McDonald's is suing Steve Easterbrook, the CEO it ousted last year over an inappropriate relationship with an employee, alleging he covered up relationships with other employees and destroyed evidence.Easterbrook told the company that there were no other similar instances.McDonald's says in a lawsuit that it has since become aware of sexual relationships between Easterbrook and three other employees prior to his termination.The company also says Easterbrook approved a special stock grant for one of those employees worth hundreds of thousands of dollars.An Associated Press message seeing comment was left with Easterbrook's attorney. 655

(CNN) -- Bank of America is raising its minimum pay to an hour for its more than 205,000 employees.The company will implement the new minimum wage over the next two years, according to comments made by CEO Brian Moynihan on MSNBC earlier Tuesday.Paychecks will initially be raised to an hour starting May 1, before climbing incrementally until 2021. Two years ago, the bank's employees got a raise to a minimum of an hour, according to a company press release.BofA is not the first main street bank to up minimum compensation for its employees. In January last year, JPMorgan Chase announced its intention to raise wages to a minimum of to for 22,000 employees depending on the local cost of living, and committed to an hour for employees in Washington in November.Bank of America declined further comment on the matter. 852

(AP) -- Not even the coronavirus could stop the 30th annual Ig Nobel ceremony, which annually recognizes sometimes dubious but always humorous scientific achievement. The event is usually held live at Harvard University, but Thursday's awards presentation was a virtual prerecorded affair. One winner is an anthropologist who tried to fashion a knife out of frozen human feces. Another is a researcher who found that people who study insects for a living are creeped out by spiders. President Donald Trump and several other world leaders also won Ig Nobels for insisting they're smarter than scientists in dealing with the pandemic. 640

"We are experiencing a teacher shortage in Florida. With a strong economy and plenty of jobs available in other fields, unfortunately too many college graduates are unwilling to enter the teaching profession. My proposal to increase the minimum salary for teachers to ,500 will help alleviate this shortage and elevate the teaching profession to the level of appreciation it deserves. This is long overdue, and I look forward to working with the legislature to make this a reality." 493

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