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david olick
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This is a cool talk. The presenter, Latif Nasser, is the director of research at +Radiolab. So you know he knows how to make talks interesting. In this case he intersperses his own comments with a recorded interview he did with the person whose discovery he discusses.  Very well done.

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NEW VIDEO! What is the specious present? And how can your brain reverse causality?

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And then someone asked me why I need more RAM in my laptop...


#pixelpushing  
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Studies show that allowing parents to choose the schools their kids attend doesn't change the kids' test scores. This outcome flies in the face of the predictions of many [conservative] economists, who often tout school choice as a way to improve the U.S. educational system while also increasing equality of opportunity. ... The evidence is by now fairly clear -- if the U.S. cares about academic success, policy makers should focus not on turning the school system into a marketplace, but on reforming existing schools to improve their quality.

And the way to improve quality is not by putting schools and teachers in direct competition with each other as in a standard marketplace. Education is not a commodity; teaching is not a fungible commercial service. We have to spend more time actually thinking about how to improve education rather than assuming the market will solve the problem. 

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How to solve an unsolvable 15-puzzle.  We know that there are two disjoint set of configurations for the 15-puzzle. One set contains the normal arrangement and the configurations that can be reached from it -- or from which it can be reached. The other is shown below. (The 14 and 15 pieces are reversed.) The configurations reachable from this arrangement and that can reach this arrangement are disjoint from the other set of configurations. In other words, the puzzle shown below is not solvable. It's not possible to reverse the 14 and 15.

But it is -- of course with a cheat. But the cheat doesn't involve breaking the puzzle. Watch the video. 

This comes at the end of a video which talks about these puzzles and their history.

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Why are there "dew drops" at the tips of leaf veins?

❦ Have you ever seen clear orbs of water glisten along a leaf edge? You may have mistaken them for dew drops, which are caused by moisture from the air condensing on cool surfaces. But these drops are only found at the edges of leaves and if you look around- they won't be found on dead leaves. So what are they?

❦ Plants use a plumbing system of xylem tubes to move water and nutrients. During the day, transpiration (water evaporation) from leaves creates a vacuum that pulls the column of water up from the roots to the leaves. At night, the stomata (leaf pores) close, transpiration stops and salts accumulate in the xylem of roots, drawing in water from the surrounding soil by osmosis. The excess water rises up the xylem tubes and is forced out at the leaf tips through openings called hydathodes. This exudation of plant sap is known rather inelegantly as guttation, and only happens at night. The water pressure is not strong enough to rise beyond 3 feet, so guttation is not seen on tree leaves. The thermal image (inset) taken by infrared photography shows the cooler temperature (blue) in the guttation droplets.

❦ When the drops dry, they sometimes leave behind a residue of salts and minerals. This is not a problem, unless the soil is over-fertilized resulting in fertilizer burn of leaf tips. In the same way, guttation droplets in corn seedlings were shown to have high levels of neonicotinoid compounds, used as pesticidal coatings on the seed. These concentrations could be a lethal dose for honey bees that sip on guttation drops as a water source. While shedding toxins through guttation drops protects the plant, it may have repercussions - both beneficial and harmful, on insects and other animals. 


Inset of thermal image: http://thermal-imaging-blog.com/index.php/page/13/#.Vq1LIvkrLcs

REF on neonicotinoids in guttation droplets #openaccess: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284396/
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