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Here's one relevant paper, Spatial and temporal dynamics of the endothelium, from the Journal of Thrombosis and Hemostasis. There's a breakdown of their findings that includes the measurements. The paper itself is more about how the phases of hemostasis are far more integrated than previously thought, but the research quotes the relevant studies they're based on. There's 154 references, and I'll bet one of them is the actual measurement parameters.

...apparently "lost in time"..

This is not actually true and demonstrates the difficulty with analogies. The radius of curvature at any point is defined as the radius of a circle which exactly matches the curve at the point concerned. The curvature is defined as the reciprocal of the radius of curvature. For flat geometry or straight lines the curvature is zero. If the curve is a circle then the radius of curvature is the same at every point. If we now let that circle expand so that the radius tends to infinity, the reciprocal of that radius tends to zero ie straight or flat. But for your parabola, the radius of curvature is different at every point and remains finite at all points between the vertex and infinity. So its curvature is never zero, except at infinity and the vertex. These two examples do nicely show the difference between local and global however. For a circle, changing the radius affects every point on the circle equally. That is global. For a parabola the fact that the parabola radius of curvature approaches infinity as the parabola approaches infinity does not affect (the curvature of) any of the points on the parabola which already have a finite curvature. Curvature for a parabola is local to each and every point on it. It's not zooming out that makes things approximately flat, it's zooming in.

This is probably off topic in this thread Swansont, so please move or split off. This site purports to be a teaching/learning discussion site. Learning implies a modification/expansion of your thinking. So why assume, as the sock puppet rule does, that someone, who use to be a jackass, and got banned, has learned nothing from the interaction, and deserves to be automatically banned ( even while posting some interesting/thought-provoking and controversial questions ). I did agree to these rules on joining, so I'm not asking for a change of the rules; just an explanation of the thinking behind that particular rule.