Disproving Spontaneous Generation essays

Disproving Spontaneous Generation essays It was a commonly held belief in Ancient Rome, during the Middle Ages, and even until the late nineteenth century that spontaneous generation, or the sudden generation of complex life from nonliving matter, existed. (Evers, 1999) Scientists began to question this theory as early as the second half of the seventeenth century, but it was not until almost 200 years later that Louis Pasteur definitively disproved spontaneous generation and changed the course of scientific thought. While it is still debated whether any forms of Abiogenesis, or the generation of even simple or microscopic life from nonliving matter, could be possible (Wilkins, 2004), it is certain that spontaneous generation involving complex life The first recorded Westerner to suggest spontaneous generation was Anaximander, a philosopher from the BC 600's and 500's. His pupil, Anaximenes, wrote that air imparted life, motion, and thought. Xenophanes and Parmenides thought that plants and animals would spontaneously form under sunlight. Empedocles wrote in the BC 400's that spontaneous generation is possible if there are the correct combinations of parts of animals to rise. (Wilkins, 2004) Aristotle, in the times of Ancient Greece, believed that life was the result of the ether, a substance which existed only in the heavens, combining with the pneuma, or the animating force or soul, and that if the pneuma was present, it would be possible for life to come from nonliving material. (Wilkins, 2004) In 1668, Francesco Redi, a physician and poet, attacked the idea of spontaneous generation. In his famous experiment, he set out meat in a variety of flasks, some of which were completely open, others covered with a gauze or mesh material, and others were sealed off completely. When maggots appears only on the meat which was exposed to the air, and therefore to flies, his theory that maggots came fro...

Astronaut Dr. Bernard Harris, Jr. Biography

Astronaut Dr. Bernard Harris, Jr. Biography Its no surprise that there are doctors who have served as NASA astronauts. They are well-trained and particularly suited to study the effects of space flight on human bodies. Thats exactly the case with Dr. Bernard Harris, Jr., who served as an astronaut aboard several shuttle missions beginning in 1991, after serving the agency as a flight surgeon and clinical scientist. He left NASA in 1996 and is a professor of medicine and is CEO and Managing Partner of Vesalius Ventures, which invests in healthcare technologies and related companies. His is a very classic American story of aiming high and reaching amazing goals both on Earth and in space. Dr. Harris has often spoken about challenges that we all face in life and meeting them through determination and empowerment.   Early Life Dr. Harris was born on June 26, 1956, the son of Mrs. Gussie H. Burgess, and Mr. Bernard A. Harris, Sr. A native of Temple, Texas, he graduated from Sam Houston High School, San Antonio, in 1974. He received a Bachelor of Science degree in biology from the University of Houston in 1978 before following that up with a doctorate in medicine from Texas Tech University School of Medicine in 1982. Beginning a Career at NASA After medical school, Dr. Harris completed a residency in internal medicine at the Mayo Clinic in 1985. He joined the NASA Ames Research Center in 1986, and focused his work on the field of musculoskeletal physiology and disuse osteoporosis. He then trained as a flight surgeon at the Aerospace School of Medicine, Brooks AFB, San Antonio, Texas, in 1988. His duties included clinical investigations of space adaptation and the development of countermeasures for extended duration space flight. Assigned to the Medical Science Division, he held the title of Project Manager, Exercise Countermeasure Project. These experiences gave him unique qualifications to work at NASA, where ongoing studies of the effects of spaceflight on the human body continue to be an important focus. Dr. Harris became an astronaut in July 1991. He was assigned as a mission specialist on STS-55, Spacelab D-2, in August 1991, and later flew on board Columbia for ten days. He was part of the payload crew of Spacelab D-2, conducting more research in the physical and life sciences. During this flight, he logged over 239 hours and 4,164,183 miles in space. Later, Dr. Bernard Harris, Jr. was the Payload Commander on STS-63 (February 2-11, 1995), the first flight of a new joint Russian-American space program. Mission highlights included the rendezvous with the Russian Space Station, Mir, operation of a variety of investigations in the Spacehab module, and the deployment and retrieval of Spartan 204, an orbiting instrument that studied galactic dust clouds (such as those where stars are born).  During the flight, Dr. Harris became the first African-American to walk in space. He logged 198 hours, 29 minutes in space, completed 129 orbits, and traveled over 2.9 million miles. In 1996, Dr. Harris departed NASA and received a masters degree in biomedical science from the University of Texas Medical Branch at Galveston. He later served as Chief Scientist and Vice-president of Science and Health Services, and then as Vice President, SPACEHAB, Inc. (now known as Astrotech), where he was involved in business development and marketing of the companys space-based products and services. Later, he was vice-president of business development for Space Media, Inc., establishing an international space education program for students. He is currently serving on the board of the National Math and Science Initiative and has served as a consultant to NASA on a variety of life-science and safety-related issues. Dr. Harris is a member of the American College of Physicians, American Society for Bone and Mineral Research, Aerospace Medical Association, National Medical Association, American Medical Association, Minnesota Medical Association, Texas Medical Association, Harris County Medical Society, Phi Kappa Phi Honor Society, Kappa Alpha Psi Fraternity, Texas Tech University Alumni Association, and Mayo Clinic Alumni Association. Aircraft Owners and Pilot Association. Association of Space Explorers. American Astronautical Society, a member of the board of directors of the Boys and Girls Club of Houston. Committee Member, Greater Houston Area Council on Physical Fitness and Sports, and a member, Board of Directors, Manned Space Flight Education Foundation Inc. He has also received many honors from science and medical societies and remains active in research and business.