Search results
Results from the WOW.Com Content Network
Every vector space is a free module, [1] but, if the ring of the coefficients is not a division ring (not a field in the commutative case), then there exist non-free modules. Given any set S and ring R, there is a free R-module with basis S, which is called the free module on S or module of formal R-linear combinations of the elements of S.
The latter is impossible because a is a real number and the first equation would imply that a 2 = −1. Therefore, a = 0 and b 2 + c 2 + d 2 = 1. In other words: A quaternion squares to −1 if and only if it is a vector quaternion with norm 1. By definition, the set of all such vectors forms the unit sphere.
Nude model, nude modelling, adult model, or erotic model may refer to: . Model (art), a model who poses for any visual artist as part of the creative process Model (person), a person with a role to promote, display, or advertise commercial products
Henrietta Lacks (born Loretta Pleasant; August 1, 1920 – October 4, 1951) [2] was an African-American woman [5] whose cancer cells are the source of the HeLa cell line, the first immortalized human cell line [B] and one of the most important cell lines in medical research. An immortalized cell line reproduces indefinitely under specific ...
The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope.