= Andrew L. Waterhouse
{c}
\b[Andrew L. Waterhouse] is a wine chemist whose UC Davis profile describes research in phenolic compounds and wine <oxidation>.<Andrew L. Waterhouse at UC Davis>[Official profile, Research section]{ref} With <Brent C. Trela>, he coauthored the 1996 primary study of <resveratrol> isomer absorptivities and stability.<Resveratrol: Isomeric Molar Absorptivities and Stability by Brent C. Trela and Andrew L. Waterhouse>[Byline and Abstract]{ref}
\Image[https://wineserver.ucdavis.edu/sites/g/files/dgvnsk2676/files/styles/sf_profile/public/images/person/Andy%20Waterhouse_002.jpg?h=c6416992&itok=S7WtuqpI]
{title=Andrew L. Waterhouse, portrait identified by UC Davis}
{description=External portrait explicitly labelled Dr. Andrew L Waterhouse on the official Viticulture and Enology profile.}
An original mixture example illustrates why identifying both isomers requires more than a total optical signal. Suppose two calibrated channels obey
$$
A_1=0.01(3c_t+c_c),\qquad A_2=0.01(c_t+2c_c),
$$
where $c_t,c_c$ are trans- and cis-isomer concentrations expressed numerically in $\mathrm{\mu mol\,L^{-1}}$. These coefficients are chosen for the example, not taken from the paper. Readings $A_1=0.35$ and $A_2=0.20$ give
$$
c_t=\frac{2A_1-A_2}{0.05}=10,\qquad
c_c=\frac{3A_2-A_1}{0.05}=5.
$$
Different spectral responses make the two channels informative jointly. If their response rows were proportional, greater reading precision would not distinguish both <concentrations>. <Multivariate calibration> or separation by <chromatography> must establish the required selectivity. The measured composition is an analytical result; it does not by itself establish a health effect of consuming the preparation.
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