Sunday, October 15, 2006


Q What happens when we hallucinate?

A Although most of us immediately think of a Fear and Loathing in Las Vegas experience, or perhaps that weird guy muttering to himself on the street corner, recreational drugs and psychiatric disorders are not the only causes of hallucination. Stress, fever, illness or sleep deprivation can also trigger an episode.

Hallucination, also called sensory deception, happens when a person sees, hears, feels, smells, or tastes something that is not there. The general cause is abnormal chemical reactions, triggered by a drug or by misfiring neurons, that activate certain parts of the brain and disrupt their usual functions.

The exact nature of hallucinations is poorly understood, but here's what we know: With visual hallucinations, foreign chemicals (drugs or stray neurotransmitters) enter the synapses between the optic nerve and the occipital lobe, the part of the brain that processes visual information, triggering a signal on that neural pathway. Once the false signal reaches the brain, the occipital lobe is activated, and visual hallucination occurs. The same process occurs with hallucinations related to hearing, smell, taste (in the temporal lobes) and touch (in the parietal lobe).

If you wish to experiment (legally, mind you) with some hallucination of your own, try sleep deprivation. According to Michael Golder, a professor of psychiatry at George Washington University, "a person who has been sleep-deprived for 72 hours is as susceptible to hallucinations as someone taking LSD."

--Rachel Horn

Q Does a bland diet really help alleviate heartburn?

A Anecdotally, yes. Scientifically, no. Lauren Gerson, an assistant professor of medicine at the Stanford University Medical Center, says that none of the common dietary restrictions recommended to lessen heartburn-including limiting coffee, chocolate, caffeinated beverages, wine and citrus fruits-have stood up to scientific scrutiny.

Heartburn occurs when the ring of muscle between the esophagus and the stomach that regulates food traffic fails to close properly. This can allow stomach contents, including stomach acid, to leak back into the esophagus, causing a burning sensation. Before the 1980s, when prescription "proton-pump inhibitors" such as Prilosec and, later, Nexium were introduced, patients had to rely on feeble antacids or even surgery. Diet restriction seemed to be the best noninvasive alternative to lessen the symptoms.

When Gerson's patients complained to her about their bland diets, she decided to go straight to the source-the original studies that implicated diet in the first place-to see if there was any support for the strict limitations imposed on heartburn sufferers. After slogging through more than 2,000 peer-reviewed journal articles, she concluded that there was not. Although some foods (like carbonated beverages) were shown to cause the muscle between the esophagus and stomach to relax-a potential cause of heartburn-Gerson says, researchers never demonstrated whether consuming them would create the symptoms or if eliminating them from one's diet would lessen discomfort.

Blanket recommendations to cut out large classes of food may not be the answer to curing heartburn, but old ideas about diet are not completely obsolete, says Kenneth R. DeVault, chair of the gastroenterology division at the Mayo Clinic in Jacksonville, Florida. "If something gives you symptoms," he says, "then you should probably avoid it." Chalk one up for anecdotal evidence.

Q Why do I get a headache when I eat ice cream too quickly?

A "Brain freeze" or an "ice cream headache" hits when a cold substance makes contact with nerve endings in the roof of your mouth. A particular nerve in the back of your throat (impress your friends by calling it the sphenopalatine ganglion) stimulates the trigeminal nerve, the largest of the sensory nerves that lead from your face to your brain. The result is that characteristic stabbing pain, centered in the midfrontal part of the brain. Migraine sufferers are typically susceptible to cold-induced head-aches, and a 10- or 20-second brain freeze can often be a trigger for a longer, more severe migraine attack. There's really no way to avoid such headaches if you insist on wolfing down your icy dessert, says Seymour Diamond, founder and director of the Diamond Headache Clinic in Chicago. Next time you sip a Slurpee, just remember to take it slow.

--Rachel Horn

Q Can someone use my GPS receiver to track me?

A Conspiracy theorists can rest easy. Handheld global positioning system (GPS) receivers are just that-receivers. They are passive devices that intercept radio signals sent out by a network of 24 primary satellites in medium-Earth orbit. By timing how long a signal takes to reach the device from each of four satellites, a GPS device can pinpoint the user's position. For someone to be able to stalk you, your GPS device would have to have some way of transmitting that position data, whether by a GPS-enabled cellphone, a radio transmitter, emergency 911 services or wireless internet. Most simple handheld GPS devices are merely passive receivers and have nothing of the kind.

If a GPS device were to be used to track a person without his or her knowledge, it could cross into uncharted legal territory. "The idea that someone is able to gather a really nicely aggregated picture of your daily routine is something most people would see as an invasion of privacy," says Lee Tien, a senior staff attorney at the Electronic Frontier Foundation, a nonprofit digital-rights group. "It's not much different from having someone following you around and keeping track of where you are at all times." If you're concerned, there's an easy solution: Just disable the GPS features on your cellphone when you're not using them.

--Nicole Price Fasig

Q Can I make snow with just my garden hose?

A Sorry, Jack Frost, but setting your puny garden hose to "mist" when it's cold outside isn't going to turn your frozen lawn into a sledding hill. Why not? The problem, in a word, is dirt. Natural snow forms in the upper atmosphere when tiny water droplets adhere to ice crystals or a small speck of dust and then change from super-cooled liquid water to solid ice. These crucial dust and ice "nucleation" points are missing from your DIY snow venture, says Matthew Pittman, co-founder of snow-machine manufacturer SnowatHome in Connecticut. "Just spraying water in a freezing environment won't make snow," he explains. "The water will not freeze until it makes contact with the ground."

Professional snow-making machines, which use a proprietary blend of nucleation particles, suck up 150 gallons of water a minute to keep the slopes of your favorite ski resort covered with the white stuff. A typical garden hose spews out a paltry six gallons a minute. So even if you did manage to get your water droplets to form snowflakes before they hit the ground, all you could hope for is a very slow accumulation, and the smallest snowman ever.

--Carla Thomas

An asteroid the size of the Rose Bowl is on a collision course with Earth, and scientists are racing to prevent an impact. (The rock, Apophis, has a 1-in-40,000 chance of striking Earth in 2036.) On this season's first episode of Nova: ScienceNow, researchers consider crashing a satellite into the asteroid to nudge it off its course or flying a gravitational tugboat in front of it to influence its path. Also covered in this hour-long episode: the struggle to create the 114th element, and a look at a genetic defect that may contribute to some forms of obesity. Airs October 3.


Sometimes it takes a kid to ask the important questions. Like, "Can we drink beer in space?" (Answer: Yes, although booze is strictly verboten to today's astronauts while they're in orbit.) Kids to Space: A Space Traveler's Guide is a gigantic Q&A on space exploration between North American schoolchildren and 80 experts in such fields as astrophysics, dentistry, and survival in extreme environments. The questions and answers are surprising and gratifying: Nationality of kids born in orbit? (Same as the parents'.) Will my cat survive liftoff? (Yes.)

By: Horn, Rachel, Fasig, Nicole Price, Popular Science, Oct2006

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