Even bet­ter than a self-clean­ing oven, we ben­e­fit from a self-clean­ing brain

The Woolwich Observer - - LIVING HERE - WEIRD NOTES

Q. His­tory buffs, have you ever wanted to visit some of the camps that Mer­ri­weather Lewis and Wil­liam Clark set up dur­ing their two-year round trip from Illi­nois to the Pa­cific coast? What un­likely source might help you as­cer­tain that these lo­ca­tions are ac­cu­rate? A. Al­though the ex­plor­ers pro­duced a wellde­vel­oped se­ries of maps, they are not the an­swer, since map­mak­ing of the time lacked to­day’s tools — GPS tech­nol­ogy, aerial cam­eras, and the like, says Dan Lewis on his “Now I Know” web­site. No, the key is that we know where the team set up their la­trines. Since along the way they needed some­thing to fight off in­fec­tion, they used calomel, a lax­a­tive that killed bac­te­ria but also con­tained a high level of toxic mer­cury.

Ar­chae­ol­o­gists at­tempt­ing to de­ter­mine the ex­act lo­ca­tion of a camp­site can test a nearby la­trine for mer­cury, “which shouldn’t ap­pear in na­ture other­wise… and stays be­hind ef­fec­tively for­ever.” One such site — Trav­el­ers’ Rest State Park in Mon­tana — has been iden­ti­fied “as def­i­nitely a Lewis and Clark (rest) stop based on the mer­cury in the la­trines. But more, hope­fully, will be iden­ti­fied over the com­ing years.” Q. How might a blind per­son re­hearse the lay­out of a place in a new city be­fore trav­el­ing there? A. By uti­liz­ing Mi­crosoft’s ‘canetroller,’ “a walk­ing cane that sim­u­lates the feel­ing of real ob­jects with vi­bra­tions” and that in­cludes au­di­tory feed­back as well, re­ports “New Sci­en­tist” magazine. With the dig­i­tal world thus opened up to the blind, one woman stand­ing in an empty 22-square-me­ter room said she felt like she was “hit­ting up against” the vir­tual room’s walls. A man said he could “feel tex­tured sur­faces.” Adds Mi­crosoft’s Mered­ith Mor­ris: “It could even be used to prac­tice nav­i­gat­ing in the snow in ad­vance of a storm ...” Q. Male crick­ets woo by vig­or­ously rub­bing their ridged wings to­gether to call fe­males, but over time up to 95% of male ocean crick­ets on sev­eral Hawai­ian is­lands have evolved flat wings, “leav­ing them mute.” Is there an up­side to this un­wel­come devel­op­ment? A. The down­side, of course, is that this mute­ness hurts their chances of mat­ing, re­ports “New Sci­en­tist” magazine. But it also pro­tects them from a par­a­site that “homes in on a male’s song and sprays the cricket with eggs. The lar­vae then eat the cricket.”

De­spite their si­lence, these males still rub their wings to­gether, says Nathan Bai­ley at the Univer­sity of St. An­drews, UK (“Bi­ol­ogy Let­ters”). It seems that while “some an­i­mals have ves­ti­gial or­gans with no func­tion, these crick­ets have ves­ti­gial be­hav­ior.” Q. You’ve heard about “self-clean­ing ovens” and may even own one. But all of us “own” our own “self-clean­ing brains.” Ex­plain, please. A. The brain is bathed in clear liq­uid called cere­brospinal fluid (CSF) that car­ries nutri­ents in and waste prod­ucts out, re­ports “How It Works: Book of Amaz­ing Science.” A bar­rier shield­ing the brain is made and main­tained by as­tro­cytes, star-shaped cells hug­ging the blood ves­sels and con­trol­ling this in-out process. At night, the as­tro­cytes re­lax their grip and the chan­nels around the blood ves­sels widen, al­low­ing CSF to sweep through the area, car­ry­ing waste prod­ucts to­ward ves­sels where they can be re­moved via the blood­stream. Since brain cells are con­stantly cre­at­ing waste prod­ucts, with­out this mech­a­nism waste could build up, caus­ing brain dam­age.

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