eyeball. 1  Photoreceptors are the cells in the retina that respond to light. Their distinguishing feature is the presence of large amounts of tightly packed membrane that contains the photopigment rhodopsin or a related molecule.
In chemical analysis,  matrix refers to the components of a sample other than the analyte of interest. The matrix can have a considerable effect on the way the analysis is conducted and the quality of the results obtained; such effects are called matrix effects. For example, the ionic strength of the solution can have an effect on the activity coefficients of the analytes.
In mathematics, a matrix is a rectangular array of numbers, symbols, or expressions, arranged in rows and columns. For example, the dimensions of the matrix below are 2 Ã 3, because there are two rows and three columns: [ 1 9 â 13 20 5 â 6 ]. {\displaystyle {\begin{bmatrix}1&9&-13\\20&5&-6\end{bmatrix}}.} The individual items in an m Ã n matrix A, often denoted by ai,j, where max i = m and max j = n, are called its elements or entries. Provided that they have the same size, two ...