The value of screening mammograms was questioned in November 2009 when the U.S. Preventive Services Task Force recommended that routine screening mammograms for women with an average risk of breast cancer should start at age 50 instead of age 40.or example, mammograms have been shown to lower the risk of dying from breast cancer by 35% in women over the age of 50. In women between ages 40 and 50, the risk reduction appears to be somewhat less.
Vocabulary alkane alkyl group hydrocarbon An alkyl group is a piece of a molecule with the general formula CnH2n+1, where n is some integer. For example, a methyl group (CH3) is a fragment of a methane molecule (CH4); n = 1 in this case. The-yl ending means a fragment of an alkane formed by removing a hydrogen.n alkyl group is a piece of a molecule with the general formula C n H 2n+1, where n is some integer.
In organic chemistry, acetyl is a moiety, the acyl with chemical formula CH3CO. It is sometimes represented by the symbol Ac (not to be confused with the element actinium). The acetyl group contains a methyl group single-bonded to a carbonyl. The carbonyl center of an acyl radical has one nonbonded electron with which it forms a chemical bond to the remainder R of the molecule. In IUPAC nomenclature, acetyl is called ethanoyl, although this term is rarely heard.