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Why teenagers find learning a drag
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Climate changes For a trimmer figure, have an extra helping of gut bacteria butterfly schedule ILPFKDtbfdeqtfqelrqb^qfkd jbq^_lif`pvkaoljb)^ka0+0mbo P^fq^j^)G^m^k)^ka`liib^drbp
ROB WALLS/ALAMY
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FOR the first time, a causal link has been established between climate change and the timing of a natural event – the emergence of the common brown butterfly. Michael Kearney and Natalie Briscoe of the University of Melbourne, Australia, compared temperature records in the city with records of the first brown butterfly to be seen each spring since the 1940s. With each decade, the butterfly emerged 1.6 days earlier and Melbourne heated by 0.14 °C on average. Overall, the butterfly now appears 10.4 days before it did in the 1940s (Biology Letters, DOI: 10.1098/rsbl.2010.0053). The pair placed eggs of the butterfly, Heteronympha merope, in chambers where temperature could be controlled and found that warmer-than-normal conditions mean the caterpillar pupates earlier and the butterfly emerges sooner. Kearney and Briscoe then made a mathematical model combining these physiological effects of temperature with climate data. The emergence dates calculated by the model matched the historical records, strongly suggesting that global warming has driven the changes in emergence timing. “The rise in air temperature links to butterfly emergence in a cause-and-effect pattern,” says Kearney.
Why learning is tough for teens ?BFKD^qbbk^dbofp^ao^d+>pfc ab^ifkdtfqembbomobpprob^ka o^dfkdelojlkbptbobkÑqqlrde bklrde)ib^okfkdkbtqefkdp^ipl dbqpe^oabo+Klt^jlib`ribqe^q `^rpbpqefpib^okfkdabcf`fqe^p _bbkclrkafkjf`bÌ^ka_il`hba+ Arofkdmr_boqv)ib^okfkd^ i^kdr^db)k^sfd^qfkd^olrka^ kbtil`^qflk^kaabqb`qfkdboolop fkqbpqpdbqe^oabo+PeboviPjfqe ^ka`liib^drbp^qqebPq^qb RkfsbopfqvlcKbtVlohob`hlk qefp`lria_barbql^qbjmlo^ov fk`ob^pbfk^ob`bmqlojlib`rib qe^qfkef_fqp^`qfsfqvfk^_o^fk ^ob^hbvqlpljbqvmbplcib^okfkd+ Mobsflrpiv)eboqb^jpeltba qe^qibsbiplcqefpob`bmqlopl^ofk mr_boq^ijf`b+Qlcfkalrqfcqefp fjm^fopib^okfkd)eboqb^jmi^`ba jf`blk^olq^qfkdmi^qclojtfqe lkbpb`qflkqe^qabifsboba^jfia bib`qof`pel`h+Fkc^kqjf`bnrf`hiv ib^okbaqlaladbqebpel`h_rq mr_boq^ilkbpafaklq%P`fbk`b) ALF7.-+../3,p`fbk`b+..51/12&+ Fc^pfjfi^ojb`e^kfpj rkaboifbpqebib^okfkdabcf`fqp bumbofbk`ba_vqbbk^dberj^kp) fq`lriaib^aqlt^vpqlfjmolsb ib^okfkd+Dfsfkdmr_boq^ijf`b ^jlib`ribqe^qfk`ob^pbp_o^fk ^`qfsfqvbk^_ibaqebjqlib^ok qlaladbqebpel`h+
Exhaust goes up, up and sideways SPACE shuttle exhaust plumes tend to move and spread faster than they should – seemingly because they are fast-tracked inside a low-density part of the atmosphere. The shuttle leaves over 300 tonnes of water in the atmosphere and a 1000-kilometre-long exhaust trail. This creates a plume, parts of which travel to the poles far faster than expected. Now Robert Meier of George Mason University in Fairfax, Virginia, and colleagues have found that simple diffusion can explain the anomaly. Satellite images in a paper
to appear in Geophysical Research Letters reveal that the exhaust diffuses upwards into less dense regions of the atmosphere, where diffusion rates are naturally faster. “Once you get the gas up into a more rarefied region of the atmosphere it’s really easy to spread sideways,” says Meier. He adds that better understanding of such high-altitude processes will help explain why “noctilucent” clouds have become more common in the past 50 years. They have previously been linked both to space traffic and to increased carbon dioxide levels.
27 March 2010 | NewScientist | 17
Climate changes For a trimmer figure, have an extra helping of gut bacteria butterfly schedule ILPFKDtbfdeqtfqelrqb^qfkd jbq^_lif`pvkaoljb)^ka0+0mbo P^fq^j^)G^m^k)^ka`liib^drbp
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`bkqlcqebfopr_`rq^kblrpc^q+Efm ^kat^fpq`fo`rjcbobk`b^ipltbkq altk_v^k^sbo^dblc.+4^ka.+2 `bkqfjbqobpobpmb`qfsbiv%Brolmb^k Glrok^ilc@ifkf`^iKrqofqflk)ALF7 .-+.-05,bg`k+/-.-+.6&+ ÎCloalfkd^_plirqbivklqefkd) qe^qÑp^ilq)Ïp^vpJ^qqebtAfd_v) telobpb^o`ebpafbq^ovjfih molqbfkp^qqebRkfsbopfqvlc Jbi_lrokbfk>rpqo^if^^kat^p klqfkslisbafkqebpqrav+ Qeb_^`qbof^j^v`^rpbtbfdeq ilpp_vfkef_fqfkdc^q^_plomqflk fkqebfkqbpqfkb)p^vpH^allh^+ GENE BLEVINS/LA DAILYNEWS/CORBIS
FOR the first time, a causal link has been established between climate change and the timing of a natural event – the emergence of the common brown butterfly. Michael Kearney and Natalie Briscoe of the University of Melbourne, Australia, compared temperature records in the city with records of the first brown butterfly to be seen each spring since the 1940s. With each decade, the butterfly emerged 1.6 days earlier and Melbourne heated by 0.14 °C on average. Overall, the butterfly now appears 10.4 days before it did in the 1940s (Biology Letters, DOI: 10.1098/rsbl.2010.0053). The pair placed eggs of the butterfly, Heteronympha merope, in chambers where temperature could be controlled and found that warmer-than-normal conditions mean the caterpillar pupates earlier and the butterfly emerges sooner. Kearney and Briscoe then made a mathematical model combining these physiological effects of temperature with climate data. The emergence dates calculated by the model matched the historical records, strongly suggesting that global warming has driven the changes in emergence timing. “The rise in air temperature links to butterfly emergence in a cause-and-effect pattern,” says Kearney.
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Exhaust goes up, up and sideways SPACE shuttle exhaust plumes tend to move and spread faster than they should – seemingly because they are fast-tracked inside a low-density part of the atmosphere. The shuttle leaves over 300 tonnes of water in the atmosphere and a 1000-kilometre-long exhaust trail. This creates a plume, parts of which travel to the poles far faster than expected. Now Robert Meier of George Mason University in Fairfax, Virginia, and colleagues have found that simple diffusion can explain the anomaly. Satellite images in a paper
to appear in Geophysical Research Letters reveal that the exhaust diffuses upwards into less dense regions of the atmosphere, where diffusion rates are naturally faster. “Once you get the gas up into a more rarefied region of the atmosphere it’s really easy to spread sideways,” says Meier. He adds that better understanding of such high-altitude processes will help explain why “noctilucent” clouds have become more common in the past 50 years. They have previously been linked both to space traffic and to increased carbon dioxide levels.
27 March 2010 | NewScientist | 17