Extraneous mag, Grand 1996
By Patrick Clinton
When thither is no ostensible case, such as markweed or an bite, why does tegument itchiness? And why does it spirit near to scrape?
Erika Huddleston, Idyllwild, California
Gobs of things piddle us scabies, from histamine-releasing chemic reactions to the pitty-pat of lilliputian louse feet. When thither’s no seeming perpetrator, the causa is unremarkably dry pelt. "Dry and batty cutis loses tractableness," explains dermatologist Larry Millikan of theTulane Checkup Centerfield. "When you movement, it twitches the fiddling spunk endings." That nip is the spoil. Scrape, course, doesn’t do practically for dry bark, but it does place much of competing messages via the like nervousness, decent to concisely swim out the itch substance. The trouble is that scrape can do foster wrong, and the sanative operation itself cancause more itchiness. Comparable your mom perpetually aforesaid, if you support pick at it, it’ll ne’er get ameliorate.
Is thither rattling such a affair as sea degree? Isn’t the "grade" ever ever-changing with the tides and liquescent icebergs and former hooey?
Robert Stovall, Boise, Idaho
Yes, Robert, cypher in our earth, not fifty-fifty sea story, is downright. "Sea layer is a backbreaking evaluate to trap, because it varies much approximately the reality due to tides, seasons, and over-the-counter factors," says Steve Branchia of the Internal Sea Help. Nearly of the metre, when you see citizenry talk around sea storey, they’re referring to roughly variant on "signify sealevel," an ordinary that’s based on hourly measurements of h2o levels interpreted at diverse stations some the mankind. Scientists fit that sea floor is presently rise at a place of approximately a mm and a one-half annually, a computing that factors in a unscathed heap of geophysical variables. E.g., some Galveston, Texas, sea floor appears to be risingfaster than the worldwide grade because the demesne thither is subsidence, a outcome of oil origin, among otc things. In over-the-counter places, such as the glide of southerly Alaska, sea storey appears to be dropping, because the crawfish of enceinte glaciers is causation the landmass to ascent unnoticeably.
So which sea degree touchstone are the altitude figures ground on maps based on? Nearly of them oeuvre off of something called the Subject Geodesical Upright Datum, a kinda zero that was deliberate in 1929. You’d retrieve we were due for a new frozen detail in our lives, and we are: The NGVD is now organism replaced by the more exact N American VerticalDatum, based on 1988 information. And odds are, when the new alt figures filter in, you’re expiration to sicken in the earth.
Why are lizards constantly doing push-ups?
Jim Caldwell, Torrance, California
It’s a mannikin of communicating. Lizards use the "push-up show," as it’s called, to foretell their front to the man, to appeal couple, and to monish competitors off their turf—or fundamentally to say "Yo!" "Yo, babe!" and "Yo’ mamma!" The accurate content depends onthe turn of push-ups, the post of the arse and legs, and whether the lizard puffs up his pharynx. (I say "his" pharynx because males look to do push-ups with greater frequence than females.) According to University of Oregon biota prof Emilia Martins, whose thesis tortuous 150 hours in the subject observation around 1,600 calisthenic incidentsperformed by sagebrush lizards (earnestly!), a push-up that way one matter when no one’s about can take a dissimilar import when, say, an eligible distaff is sunning herself on the future stone. It’s a attaint citizenry ne’er picked abreast this cast of terminology. Not lone would we be more dynamical conversationalists, but, same Jackass Palance, we’d all be interrific bod.
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