Which kind of sun tan lasts longer?

Chemical sunscreens (e.g. avobenzone) are rich in C=C and C=O groups. Why are these groups particular useful in absorbing UV rays?

Based on genetic analysis of the MC1R gene, biologists estimate that body hair loss and brown skin appeared in the human line around:  

Which type of melanin has two forms: black (DHI) and brown (DHICA)?  

Achromotrichia refers to the __________ of hair.

Keratinocytes have a photoreceptor protein that detects UV light and is responsible for forming and positioning:  

What element in pheomelanin (derived from cysteine) is the primary reason why it appears lighter in color than eumelanin?  

Two common chemical sunscreens, oxybenzone and octinoxate, have been banned in Hawaii, Palau, nature reserves in Mexico, Bonaire, Aruba, The US Virgin Islands, the Marshall Islands, and Thailand’s marine natural parks. Experiments have shown these sunscreens are toxic to:

The same cell types that make eyelashes curve are the same as those that make hair curly.

Tom has an unfenced backyard and has a problem with the neighborhood children who prefer to take the shortcut through his yard on the way to and back from the convenience store.  He has warned the children repeatedly that they are not permitted to enter his yard and has posted no trespassing signs along the perimeter of the proper.  This has not been successful and he has determined to teach these children a lesson by digging a pit in his backyard with a tarp over the top to hide the pit.  A child enters the property and suffers significant injury.  Can Tom be arrested or sued in this situation?