The arm bones of women who lived 7-000 years ago show a surprising level of strength-even higher than today's professional athletes. That's according to a first-ever study comparing prehistoric(史前的)bones to those of living people. The finding suggests a revision of history — the everyday lives of prehistoric women were filled with hard labor, rather than just sitting at home doing lighter tasks while the men struggled and fought for life.

    “Before the study, there are no clear records describing how our ancient ancestors lived. It can be easy to forget that bone is a living tissue, one that responds to the difficulties we put our bodies through,” said lead author Alison Macintosh. “Physical force and muscle activity both put pressure on the bone. The bone reacts by changing in shape, thickness and other aspects over time. ”

    Previous studies only compared female bones to contemporary male bones, the researchers said — and that's a problem, because the response of male bones to stress and change is much bigger than that of women. For instance, as humans moved from a hunter-gatherer lifestyle constantly on the move to a more settled agrarian (农耕的)one, changes can be observed in the structure of the shinbone (胫骨) — and these changes were much more evident in men.

    However, a comparison of the bones of prehistoric women to the bonos of living female athletes can help us work out a more accurate picture of what those prehistoric women were doing. “By analyzing the bones of living people and comparing them to the ancient hones, we can start to explain the kinds of labor our ancestors were performing,” Macintosh said. What they found was that women's leg strength hasn't changed a great deal, but their arms used to be very powerful. Prehistoric women, the researchers found, had arm strength 11〜16 percent stronger than those of modern rowers, and 30 percent stronger than those of non-athletes.

    Now women are free to enter any career that attracts them, and working can bring them pride, confidence and independence. Working women make up nearly half of the U.S. workforce, and 51 percent of professional workers, like doctors, lawyers, nurses and accountants, are female. While climbing the career ladder can be rewarding, it often comes with one big disadvantage: weight gain!

    New research published this week in the International Journal of Obesity shows that working women are more likely to be overweight, and the more you work, the more pounds you're likely to pile on. Like many women, I work... a lot! As a self-employed nutrition communications specialist, I sit at my desk, in front of a computer, for hours on end. Sitting alone is one of the worst things you can do for your health, and it's directly linked to being overweight and increased fatness, so the fact that women in the workforce gain weight isn't that surprising. If you work, you have less time to move around. Obesity researchers are revealing many other ways that employment is harmful to your diet and waistline(腰围).

    In the International Journal of Obesity study, some 9,276 Australian women aged 45-50 had their body weight and employment status monitored for two years. Results? Those who worked more than 35 hours were likely to gain weight compared to those who worked fewer hours or were out of the workforce. What's more, the more hours a woman worked in a week, the more weight she gained.

    The authors of the Australian study attribute weight gain among working women to inactivity, lack of time for food preparation, more use of prepared foods, high levels of stress, lack of sleep and consuming more alcohol. I'll also add in travel, meals eaten out and working at night as other factors that I can find to make balancing work with a healthy diet a challenge.

    Abraham Lincoln, a self-taught lawyer, was elected 16th president of the United States in November 1860, shortly before the outbreak of the Civil War. Lincoln proved to be a smart military strategist and a competent leader: His Emancipation Proclamation (解放宣言) paved the way for slavery's abolition, while his Gettysburg Address stands as one of the most famous speeches in American history. In April 1865, with the Union on the brink of victory, Abraham Lincoln was killed; his untimely death made him a hero to the cause of liberty, and he is widely regarded as one of the greatest presidents in U.S. history.

    On January 20, 1981, Reagan took office. Only 69 days later he was shot by a would-be killer, but quickly recovered and returned to duty. His grace and wit during the dangerous incident caused his popularity to soar.

    At the end of his two terms in office, Ronald Reagan viewed with satisfaction the achievements of his innovative program known as the Reagan Revolution, which aimed to motivate the American people and reduce their reliance upon Government. He felt he had fulfilled his campaign pledge of 1980 to restore "the great, confident roar of American progress and growth and optimism."

    When George W. Bush, at the age of 54, became the 43rd president of the United States, it was only the second time in American history that a president's son went on to the White House. John Quincy Adams, elected the sixth president in 1824, was the son of John Adams, the second president. While John Adams had brought up his son to be president. George Bush, the 41st president, insisted he was surprised when the eldest of his six children became interested in politics, became governor of Texas, and then went on to the white House.

    Barack Obama served as the 44th President of the United States. His story is the American story—values from the heartland, a middle-class upbringing in a strong family, hard work and education as the means of getting ahead, and the belief that a life so blessed should be lived in service to others.

    With a father from Kenva and a mother from Kansas, President Obama was born in Hawaii on August 4, 1961. He was raised with help from his grandfather, who served in Patton's army, and his grandmother, who worked her way up from the secretarial pool to middle management at a bank.

    You've heard the old advice that skipping meals is a sure-fire way to ruin a weight loss plan, but a new study presented this week at the annual Obesity Society Meeting in New Orleans suggests that perhaps we've overlooked the benefits of selective fasting. According to the research, eating during a smaller window of time each day and skipping your evening meal could have a positive health effect.

    The study concluded that overweight individuals who ate during the day and fasted during the evening reported fewer hunger swings and burned more fat at night, WebMD reported. However, although this diet plan results in more fat burned in the evenings, it did not seem to increase fat burning overall. Due to this, at this moment it's still unclear as to how this eating schedule can affect general weight loss.

    "At this point, we are not sure whether or not total fat burning is increased," study lead author Courtney Peterson told Medical Daily in a recent email." We will need to do a larger study to find out for certain whether or not time-restricted feeding improves fat burning."

    Still, although the results do not indicate a clear association between nighttime fasting and weight loss, they are still important for the world of nutrition. For example, Peterson told Medical Daily that she was surprised to find that participants did not report being hungrier than average, or have above-average swings in hunger levels, despite fasting daily for 18 hours.

    "So we overturned the belief that fasting for longer period each day when the same number of total calories are eaten makes a person hungrier, "wrote Peterson.

    While the effects of fasting and time-restricted feeding have been studied and proven to work in a rodent(贴齿动物)model, research on human subjects is still in its early stages. For this reason, Peterson explained that it is far too early to say, with factual evidence as backing, that time-restricted feeding will improve weight loss in humans. Still, Peterson explained that practicing this eating behavior does have obvious benefits, such as reducing overall food intake, and suggested that practicing time restricted eating a few times a week could be both practicable and healthy.

    "It could be used for short-term goals or longer-term goals，"concluded Peterson." As far as we know，it is safe for adults，although pregnant women and children should not try it."

    The school year has barely started in Denver, and French teacher Tiffany Choi is already worried that her students are suffering from absent-mindedness. The problem isn't texting, playing video games or passing notes. It's Denver's ongoing heat wave.

    "Today was a little bit hot, so I noticed kids were very sleepy and they were having to get up to drink water quite often." said Choi, who works at Denver's East High School. "If you lose too much water, and you have to keep going to the water fountain, that can take away from their classroom experience." While nodding off in class on a warm day may seem like a right of passage for the average teen, Choi's observation carries a bigger consequence than parched (干燥的) lips.

    "There's been quite a few media reports about teachers noticing that students weren't able to focus on hotter days," said R Jisung Park, a researcher, "Does a hotter climate during the school year actually affect the rate of learning?" The drops in academic achievement couldn't be explained by hotter weekends or hotter summers, but the trend was connected to higher temperatures on school days alone.

    The connection between lost learning and a greater number of hot days is one more example of how climate change is already affecting our lives-and it's an alarm bell for what we stand to lose in the future. Humans still have time to lessen the worst consequences of continued global warming. But unless significant changes occur in the next decade-which seem more and more unlikely—the world will be locked into an inescapable period of heat waves unlike our species has ever seen.

Teenagers who spend more than six hours online on school days are more likely to be lonely and skip school,according to an international study.

The study examined the home Internet use,well-being(幸福) and behaviour of 296,000 15-year-olds in 41 countries.More than one in four spent more than four hours per day online outside of school.The study found lower levels of well-being among students who spent more than six hours per day online.They were twice as likely as teenagers spending one and two hours per day online to report that they felt lonely at school.These extreme Internet users were also especially at risk of "behaving in problematic ways at school,such as arriving late or skipping class".

The report said,"Lower levels of engagement(密切关系) with school may be connected to less sense of belonging at school.It is also possible that skipping class and arriving late for school are the consequence of lack of sleep among extreme Internet users."It adds,"Parents,schools and health professionals can work together to watch and plan children's use of new media."

The study also found that countries that invest(投资) heavily in Information and Communication Technology(ICT) in schools have seen no considerable difference in 15-year-olds' achievement in reading,maths or science tests.The study results suggest limited use of computers at school may be better than not using them at all.However,students who use computers very frequently at school do a lot worse in most learning outcomes.The report says,"In the end,technology can strengthen great teaching,but great technology cannot replace poor teaching."