Why do bags form below our eyes?
—K. Davin, Juneau, Alaska

Rhoda S. Narins, clinical professor of dermatology at New York University Medical Center and president of the American Society for Dermatologic Surgery, explains:

Dark circles and bags under the eye occur for several reasons: the skin there is much thinner than it is elsewhere on the body and becomes looser as we age. This very thin skin also sits on top of underlying purple muscle and blood vessels and therefore appears darker. In addition, some people have hereditary pigmentation in this area. As we age, fat comes out of the space enclosed by the eye socket, called the orbit, and forms a puffy area under the eye. This fatty tissue can fill with water, making the hollow appear even deeper. The condition becomes even more noticeable when water is retained in the fat pad, which can occur for a variety of reasons, including eating too much salt, lying flat in bed, not getting enough sleep, allergies and monthly hormonal changes.

Treating the hollow space under the eye is straightforward and can be done by injecting a filler such as Restylane. Immediately after this procedure, the so-called tear trough is softened, and any visible pigmentation becomes noticeably lightened. A carbon dioxide (CO2) laser also can be used to resurface the skin, which tightens and thickens it as well as lightening the coloring. For hereditary pigmentation, CO2 laser resurfacing and bleaching creams are sometimes helpful. As an option, a surgeon can perform blepharoplasty to fix the fat pad under the eye.

Simple, nonsurgical measures to reduce the puffiness and darkness of under-eye circles include avoiding salt, using cold compresses on the eyes, getting enough sleep, treating allergies, as well as sleeping with your noggin higher by resting it on two pillows or raising the head of the bed.

How are the abbreviations of the periodic table determined?

Michael R. Topp, professor of chemistry at the University of Pennsylvania, offers this answer:

Although some of the symbols in the periodic table may seem strange, they all make sense given a little background information. For example, the symbol for the element mercury, Hg, comes from the Latin word hydrargyrum, meaning “liquid silver.” Many other elements that were known to the ancients also have names derived from Latin.

The rare (or inert) gases were discovered more recently and tend to have classical-sounding names based on Greek. For example, xenon (Xe) means “the stranger” in Greek and argon (Ar) means “inert.” Helium (He) is named after the Greek god of the sun, “Helios.”

So far 110 elements have been formally named. The “new” elements are synthetic, and each one's detection needs confirmation. After the finding is confirmed, the discoverers may propose a name, and then the moniker is officially determined jointly by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP).

The proposal to name element 111 roentgenium (Rg), for instance, has been recommended for approval by the Inorganic Chemistry Division Committee of IUPAC. As it states: “This proposal lies within the long-established tradition of naming elements to honor famous scientists. Wilhelm Conrad Roentgen discovered x-rays in 1895.”

As yet undiscovered elements with higher atomic numbers receive so-called placeholder names, which are simply Latin-ized versions of their atomic numbers. Thus, element 111 was formerly designated unununium, literally “one one one” (Uuu), and element 112 has been given the temporary name of ununbium (Uub).

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