ScienceIQ.com

How Fast is Mach 1?

A Mach number is a common ratio unit of speed when one is talking about aircrafts. By definition, the Mach number is a ratio of the speed of a body (aircraft) to the speed of sound in the undisturbed medium through which the body is traveling. ...

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Mach1
Chemistry

What Are Isotopes?

Many of the known elements from which our universe is constructed exist in various isotopic forms. The identity of any particular element is defined by the number of protons within the nuclei of its ... Continue reading

WhatAreIsotopes
Medicine

SARS: Mother Nature Strikes Again!

SARS, short for Severe Acute Respiratory Syndrome, is big news this spring. By the middle of April 2003, over 2000 people had been diagnosed with it in China and Hong Kong, another few hundred in the ... Continue reading

SARSMotherNatureStrikesAgain
Astronomy

The Constellations

The random arrangement of the stars visible to the naked eye has remained essentially unchanged since the time of the first written records. One of the earliest complete lists we have was compiled in ... Continue reading

TheConstellations
Biology

Bird Flu, Swine Flu, Human Flu

Influenza, unlike many viruses that make humans sick, can also affect birds and pigs. Generally strains of the influenza virus that causes disease in people are slightly different from those that ... Continue reading

BirdFluSwineFlu

Neurogenesis

NeurogenesisUntil recently, any doctor would have told you that when you lose brain cells, you can never replace them. Scientists now know that the human brain has the ability to regenerate brain cells, or neurons, a process known as neurogenesis, in at least the hippocampus (used for memory) and olfactory bulb (used for smell).

If your hippocampus isn't working right, you can't learn anything new or access recent memories. Damage to your hippocampus can make it impossible to create new memories (a condition called anterograde amnesia - Leonard Shelby's condition in the movie Memento) or remember what happened in the days or months before the accident. The hippocampus is also one of the first brain structures to be damaged by Alzheimer's Disease. That's why Alzheimer's first shows up as difficulty with recent memories, while memories of long-ago events remain intact until the disease is more advanced.

When your olfactory bulb stops replacing its cells, it's often a sign that there's something wrong with other parts of your brain, too. Loss of smell in old age can be a sign of Alzheimer's, perhaps because when the brain stops replacing olfactory cells it stops replacing cells in the hippocampus-based memory system as well. That's why one of the latest diagnostic tools for Alzheimer's is a scratch-and-sniff test.