R. Fourme

R. Fourme coauthored the 1984 high-resolution structure of human deoxyhemoglobin with G. Fermi, Max Perutz and B. Shaanan. The primary record describes X-ray diffraction collected on film at room temperature using synchrotron radiation, followed by refinement at $1.74\mathring{\mathrm{A}}$ resolution.^[ref] This establishes a contribution to experimental structural biology; the byline alone does not assign each instrument or calculation to one coauthor.

The physical chain is illuminating: a crystal scatters the incident radiation, a detector records diffraction intensity, and a model connects the measurements with an electron density distribution. Improving incident flux can help collect weak reflections, but flux and spatial resolution remain different quantities.

For an original counting example, suppose an ideal detector records 400 independent photons in one reflection and background is negligible. A Poisson distribution then gives standard uncertainty $\sqrt{400}=20$ counts, or 5% relative uncertainty. Four times as many recorded photons gives 1,600 counts and $40/1600=2.5\%$ relative uncertainty. The square-root improvement describes the chosen counting model; it is not a measured uncertainty for the historical film detector.

Increasing exposure also need not preserve the specimen unchanged. A comparison should keep track of radiation-induced changes, detector response and background rather than assuming that every additional count is interchangeable. Those experimental controls complement the molecular constraints used in X-ray crystallography. Fourme's verified coauthorship connects the biological question to the apparatus needed to obtain its structural evidence.