HOW LASERS WORK: "Laser" is an acronym for Light Amplification by Stimulated Emission of Radiation. It describes any device that creates and amplifies a narrow, focused beam of light whose photons are all traveling in the same direction, rather than emitting every which way at once. Lasers can be configured to emit many different colors in the spectrum, but each laser can emit only that one color. There are many different types of laser, but all of them have an empty cavity containing a lasing medium: either a crystal like ruby or garnet, or a gas or liquid. There are two mirrors on either end of the cavity, one of which is half-silvered, meaning that it will reflect some light and let some light through. In a laser, the atoms or molecules of the lasing medium are "pumped" by applying intense flashes of light or electricity. The end result is a sudden burst of so-called "coherent" light as all the atoms discharge in a rapid chain reaction.
HOW DO E. COLI AND SALMONELLA GET INTO OUR FOOD? E. coli is a type of bacteria that often resides within the intestinal tracks of many animals, including people. Many strains are harmless, but strain 0157 causes serious food poisoning. In the intestines, the bacteria help to maintain health by producing vitamin K, and by keeping other species out. When fecal matter, manure, or pieces of the intestines are poorly processed and come into contact with meat or vegetables, the bacteria contained within them can attach themselves to food. Salmonella is also a bacteria, capable of causing diarrhea and other potentially severe illnesses. It can be found in water, fecal matter, and the intestines of mammals and birds. The best defense against infection is careful cleaning and cooking of meats and eggs.