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Sunscreens can help. Sunburn occurs when strong UV rays harm cells in the skin’s outermost layer, the epidermis. Blood vessels in deeper layers dilate, turning the skin red: a sunburn. Regular exposure causes the epidermis to produce more melanin pigment in an attempt to absorb UV rays. If enough melanin accumulates, the skin darkens: a tan. Dark-skinned people have more melanin than light-skinned people and so don’t burn as readily. Active chemicals in sunscreen also filter UV rays, slowing injury and thus the sunburn and tanning reactions.

The park’s dolphins touch images with their rostrums (noses). When a dolphin mimics the computer sound for “up” and then swims upward, a bit of language is born. The dolphins get no food rewards, only recorded sounds and video they find intellectually stimulating. TOUCH TV Bill Colwell, an engineer at Elo TouchSystems, developed the first touch screen in 1977. The key to commercializing the resistive design was a subsequent Elo patent for polyester “dots” that separated the screen’s layers [see diagram on opposite page].

FADING FAD: When a flea bites, it deposits saliva in the skin. Pets can have an allergic reaction that causes redness and severe itching. As they scratch, they develop flea-allergy dermatitis. For years, FAD was the leading skin problem in dogs and cats, but veterinarians report that “spot” treatments, because of their quick kills, have dramatically reduced the incidence of the disorder. BLACK DEATH: Rat fleas carry bacteria that can cause plague, such as the bubonic plague that wiped out one third of Europe’s population in the 14th cen- tury.

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