Q: Regarding your column about cell phone risks, do cordless phones in the home pose the same potential risks since they are also transceivers?
David Seltzer
A: Just as is true that some studies indicate cell phone radiation is harmful and other studies say it is not, there is the same kind of split when it comes to cordless phones. I'm not qualified to judge who is right and -- when it comes to a possible cause of cancer -- it seems dangerous to guess. So instead I'll report that the federal government's National Cancer Institute has this to say comparing risks from cell phones and cordless phones: "Cordless phones (phones that have a base unit connected to the telephone wiring in a house) often operate at radio frequencies similar to those of cell phones; however, since cordless phones have a limited range and require a nearby base, their signals are generally much less powerful than those of cell phones." You can find the Cancer Institute's complete views on radiation dangers from cell phones and cordless ones at this Web address: http://www.cancer.gov/cancertopics/factsheet/Risk/cellphones
Q: A recent column of yours begs the question: Why aren't files actually gone when deleted?
Bruce Coppedge
A: When you hit the delete button on your computer, the file does not disappear from the hard disk. Instead, the space that file continues to occupy is marked as available for use. So until that space is used -- until new data is written there -- the file remains and can be easily retrieved using readily available software. It's even remotely possible to retrieve at least part of the data after the space is used, but the level of difficulty vastly increases and the chance of success vastly decreases. Eventually, with enough disk activity it becomes impossible to retrieve any of that data.
Q: In a column about television antennas you did not mention the "box" that cable subscribers were told they'd need if they gave up cable. Is that still necessary for switching to antenna signals?
Carolyn May
A: When television stations switched from analog broadcasts to digital, the old-style analog TV could no longer receive the signal. Newer HDTV sets are digital by nature and can receive the signal. The box you mention is basically a digital receiver designed to be used with the older sets. Owners of the old style analog TVs need to connect that box to receive over-the-air digital signals. The box first receives the digital signal and then converts it to an analog signal the old TV can handle. So the box is necessary if you have the old style television and isn't necessary if you have an HDTV or other digital TV.
