Other frequencies can be used, but not by the 60 Hz power used in the U.S., at least not without electronics seriously more expensive than a simple ballast.
You mean like the smart chips that are mandated by the Telecommunications Act of 1996, that are going to be put in EVERY electrical device sold in the US starting in July of this year. Google has already announced they will be offering software enabling homowners to control, monitor, and operate everything that runs on electricity--from DVD players to toasters, to lights...
This new tech is essentially X-10 technology that is embedded into every electrical device, and can send and receive the equivalent of cable-modem digital data packets over standard house wiring.
Changing the flicker rate of lights to DIRECTLY cause human brain wave synchronization to predetermined states (Alpha, Delta, Beta, etc) is 80 year old tech, and now we have the technology built-in to all electrical devices, including the captive ballasts of CFLs.
Imagine the possibilities. The Soviets couldn't even dream up this sort of stuff...
Effects of flickering were found to be detrimental. Not much has bound to improve things.
Oh, a LOT has been done to "improvet their effectiveness" with regards to creating certain brain states. Go read the Telecom Act of 1996...
So long as an incandescent light bulb that uses 60 W of energy can be replaced by a CFL that uses 13 W, I'll use the CFL.
CFLs are a great idea until you break one. The EPA has already issued their instructions on how to deal with them if they are broken, which involve evacuating the area, opening all the windows for a few hours, and placing the broken bulb in a sealed container for proper disposal, due to the mercury in each bulb.
Yeah, a great improvement over incandescent bulbs...
Long-burn phosphors that accurately replicate the light of incandescent bulbs have been around a long time, too.
As someone who's work depends on PRECISE color accuracy in printing, I can tell you that there isn't a fluorescent bulb out there ANYWHERE (with the exception of Ott Lights) that even approaches the "naturalness" of some incandescent bulbs. The CFLs you buy in stores today--even the expensive "daylight" bulbs have pitifully low lumen outputs, are dreadful with certain colors (specifically blues and greens) and cause most red and purple inks, paints, and pigments to succumb to photosesitive degradation more quickly than direct natural sunlight.
From an artists or graphic designers POV, CFL bulbs are perhaps the WORST idea for workplace illumination ever devised. In short, they screw up the perceived color spectrum, cause MASSIVE perceptual shifts in certain colors, and degrade other colors more quickly than direct sunlight. They are a nightmare for art galleries, museums, practicing artists, and graphic designers working in print media.
The fact that they are filled with neuro-toxic mercury vapor, create nearly double the environmental pollution to produce than incandescents, and can be remotely controlled to modify, alter and even control brainwave states is just icing on the cake...
And you better believe some of the first places that will be converted entirely to CFLs are SCHOOLS--where our children will be exposed to their toxic contents.
CFLs have so many potentially negative health effects that if these effects are a coincidence, then the current crop of engineers must be some of the most incompetent people in the history of science. And if these side effects of CFLs were intentionally designed in, the level of evil behind such design practically defies imagination...