The more accurate version of this question would really be something like, "Why do some trees fall over in a storm while others stay standing?" The answer is more complex than a simple distinction between old, rotted, and weak vs. young, healthy, and strong. Instead, writes Mary Knudson at Scientific American blogs, trees fall because of their size, their species, and even the history of the human communities around them.
“Trees most at risk are those whose environment has recently changed (say in the last 5 – 10 years),” Smith says. When trees that were living in the midst of a forest lose the protection of a rim of trees and become stand-alones in new housing lots or become the edge trees of the forest, they are made more vulnerable to strong weather elements such as wind.
They also lose the physical protection of surrounding trees that had kept them from bending very far and breaking. Land clearing may wound a tree’s trunk or roots, “providing an opportunity for infection by wood decay fungi. Decay usually proceeds slowly, but can be significant 5-10 years after basal or root injury.” What humans do to the ground around trees — compacting soil, changing gradation and drainage “can kill roots and increase infection,” Smith warns.
Read the full piece at Scientific American Blogs
Image: West Philly Storm - Trees Down, a Creative Commons Attribution (2.0) image from kwbridge's photostream
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Paige and Dexter are so smart, they can even explain chemical bonds.
For the next 60 years or so—basically, until everyone roughly my age has died off—former Alaskan senator Ted Stevens will be widely remembered (and mocked) for once describing the Internet as "a series of tubes".
But here's the thing. It's easy to make fun of Ted Stevens. It's harder (much harder) to explain quickly and at a relatively simple level—for lay people with no tech background—what actually happens when they call up a web page.
That's why Greg Boustead and the nice folks at the World Science Festival put together this short video, explaining the basics of the Internet, specifically the basics of packet switching. The video should help the average person understand the Internet just a little better and it has been run by several experts for accuracy, Boustead says.
I have to admit that when I had to screen it for "father of the Internet" Vint Cerf, who invented this process, I was more than a little nervous, certain he would pick it apart. When he replied with "This is so good - can I please use it to explain the concept of packets at public lectures," needless to say, I was over the moon.
So, the Internet. It's not a big truck. It's not a series of tubes. It's more like a bus full of tourists.
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Genius science writer Ed Yong used to work for a cancer charity, so he's seen how the cancer research sausages get made. In a new post at Not Exactly Rocket Science, Ed takes you on a brief tour of the factory, explaining why even good data doesn't necessarily mean what you think it means.
The post is based around a new study that says 16.1% of all cancers worldwide are caused by infections. This statistic is talking about stuff like HPV—viruses and other infections that can prompt mutations in the cells they infect. Sometimes, those mutations propagate and become a tumor.
That statistic tells us that infections play a role in more cancers than most laypeople probably think, Ed says. It gives us an idea of the scale of the problem. But you have to be careful not to read too much into that 16.1%.
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The latest paper tells us that 16.1% of cancers are attributable to infections. In 2006, a similar analysis concluded that 17.8% of cancers are attributable to infections. And in 1997, yet another study put the figure at 15.6%. If you didn’t know how the numbers were derived, you might think: Aha! A trend! The number of infection-related cancers was on the rise but then it went down again.
That’s wrong. All these studies relied on slightly different methods and different sets of data. The fact that the numbers vary tells us nothing about whether the problem of infection-related cancers has got ‘better’ or ‘worse’. (In this case, the estimates are actually pretty close, which is reassuring.