Cassandra´s dream

            Leaves are loaded with chlorophyll, which makes them green. But all green plants also carry a set of chemicals called carotenoids. On their own, these look yellow or orange—carotenoids give color to corn and carrots, for example—but they’re invisible beneath the chlorophyllic green of a leaf for most of the year. In the fall, when the leaves are nearing the end of their life cycle, the chlorophyll breaks down, and the yellow-orange is revealed. “The color of a leaf is subtractive, like crayons on a piece of paper,” says David Lee, formerly of Florida International University, who has studied leaf color since 1973. Most trees have evolved to produce a different set of chemicals, called anthocyanins, when it’s bright and cold in autumn. These have a reddish tint and are responsible for the color of a blueberry. They’re also sometimes made in newly sprouting leaves, which explains their sometimes reddish tint. Where chlorophyll and anthocyanins coexist, the co

Tuesday, 29th October GCSE: General Certificate of Secondary Education Unskilled streamed trainer/employer trainee/employee blue collar white collar degree sixth former sixth from O level A level Assessment Vocational training Apprenticeship Scholarship optional compulsory co-ed

  The social media habit of some of my friends that I find most offputting is the frequent appearance of photos of their children.   Aside from their questionable taste, I believe these people are doing their kids a great diservice. They are making decisions that will affect their children’s future identity and privacy in ways we can barely guess at.  How much do you trust Facebook with your data, your images, and what it knows about you and your friends? Even if you’re “not doing anything wrong”, even if you are willing to trade your own privacy for the convenience of easily sharing links and vacation photos, why would any caring parent want to make those decisions for their children, choosing the riskier option?   As someone born in the 1970s, my childhood remains private, recorded only on paper diaries written by me, and on printed photographs stored on my parents’ bookshelves, mostly undigitized. My teenage peccadillos and the sins of my students days are mercifully

   

    Studies have claimed major health benefits for standing for much of the day as opposed to sitting. The difference is marked, explains Michael Mosley. Guess how many hours a day you spend sitting? Fewer than eight? More than 10? A recent survey found that many of us spend up to 12 hours a day sitting on our bottoms looking at computers or watching television. If you throw in the seven hours we spend sleeping then that adds up to a remarkable 19 hours a day being sedentary. Sitting down as much as this is clearly bad for us and some studies suggest that those who sit all day live around two years less than those who are more active. Most of us are guilty of excess sitting. We sit at work, in the car and at home, moving only to shift from one seat to another. Even if you exercise on a regular basis that may not be enough. There is mounting evidence that exercise will not undo the damage done by prolonged sitting. Our technology has made us the most sedent