History Main article: timeline of underwater technology Original Aqualung SCUBA set The first commercially successful scuba sets were the Aqualung open-circuit units developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water, and the descendants of these systems are still the most popular units today. The open circuit systems were developed after Cousteau had a number of incidents of oxygen toxicity using a rebreather system, in which exhaled air is reprocessed to remove carbon dioxide. Modern versions of rebreather systems (both semi-closed circuit and closed circuit) are still available today, and form the second main type of scuba unit, most commonly used for technical diving, such as deep diving. Etymology The term SCUBA (an … Read entire article »

Few things have caused much more excitement in scientific circles in recent years than stem cell investigation. Envision having an unlimited supply of healthy cells, tissues, even organs that can be transplanted to restore harm carried out by injury or disease.  Much like replacing worn parts of your automobile, you could go in for a cell transplant and regenerate defective tissue. The classic example, which has been practiced for over 40 years, is the bone marrow transplant. Bone marrow is harvested from a donor by puncturing the hipbone and drawing out cells with a syringe. About 1 in 100,000 cells in the marrow is in fact a hematopoietic (blood-forming) stem cell, while the rest are other kinds of white and red blood cells.(1) How the Magic Happens Actually, the “magic” part, or just … Read entire article »