Whichever theory you think is right, with the No Glass Ceilings motif index, which returned 10.1% year to date, you get a litmus test for this tectonic sociological shift occurring in our society and economy through the progress of 19 companies currently headed by female chief executives.

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When light travels through glass, it slows down (the amount it slows is measured by a number called the refractive index).

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