The results mean that "low oxygen is a naturally occurring process," but that fertilizer use has driven it "very far off scale," says Osterman, whose study appears in the April issue of Geology.
That does not mean that low turnover funds will perform better, but it does mean they will not burn cash dodging in and out of securities that may result in short-term capital gains that are taxed as ordinary income.
Others say an aging labor force and fear of downsizing mean that low unemployment no longer boosts wages.
One important caveat in the Canadian study is that the authors aren't making any strong statements about causality: There's a clear association between low population density and reported happiness, but that doesn't mean that low population density causes happiness.
But the findings don't mean that low doses of radiation are especially unhealthy, says biophysicist Richard Setlow of the Brookhaven National Laboratory in Upton, New York.
Specialised Braille and large-print keyboards and screen-reading software mean that low vision isn't an obstacle to going online.
