Below the age of 20, acne can cause dark spots due to scarring and red marks left by the infection. Skin Diseases That Cause Dark Spots Melasma: Itâs one of the commonest causes of grayish patches on the face. It mostly affects the forehead, cheeks, or the area between your mouth and nose.
The definition of a titter is a nervous and half-hidden laugh. An example of a titter is the laugh made by a schoolgirl in class. verb. To titter means to laugh or giggle in a somewhat suppressed way. An example of to titter is the laugh of a nervous toddler.
A titer (or titre) is a way of expressing concentration. Titer testing employs serial dilution to obtain approximate quantitative information from an analytical procedure that inherently only evaluates as positive or negative. The titer corresponds to the highest dilution factor that still yields a positive reading. For example, positive readings in the first 8 serial twofold dilutions translate into a titer of 1:256 (i.e., 2 â8). Titers are sometimes expressed by the denominator only, for example 1:256 is written 256.