Telstra has revealed the addition of almost one million new mobile services in the six months to December 2011, but Sensis revenues plummeted 24 percent in 12 months.
U.S. biochemist Kamal Datta, the lead researcher in the study, stated, "Radiation exposure, either intentional or accidental, is inevitable during our lifetimes. But with plans for a mission to Mars, we need to understand more about the nature of radiation in space. There is currently no conclusive information for estimating the risk that astronauts may experience." [GUMC press release: “Space Radiation May Cause Prolonged Cellular Damage to Astronauts”]
The Datta study assumes that the risk from radiation exposure should not be measured solely on the basis of accumulatived exposure but, instead, on the combined measurements of accumulative exposure and quality of the radiation.
The Datta team measured the level of free radicals and the expression of stress response genes in the cells of laboratory mice exposed to high LET radiation, similar to what astronauts would be exposed to in outer space.
Their conclusion was that the “cellular environment of the gastrointestinal tract was highly oxidative—or full of free radicals—for prolonged periods of time, a state which is conducive to cancer development.”
The radiation causes free radicals to be formed. The presence of free radicals causes damage to the DNA of cells. And, as these free radicals multiple, they can lead to mutations, such as malignant tumors--cancers.
The Datta team found that genes in cells exposed to radiation were under stress for as long as two months after exposure to high-LET radiation.
They also found that cells of their lab mice were damaged by oxidative stress; that is, the cells aged faster than normal, which causes wrinkles, sagging skin and more serious age-related medical conditions to occur.
Oxidative stress is an unbalanced state in the human body produced by the increased formation of free radicals and decreased availability of antioxidants.
Authors on the study include Kamal Datta, Kathryn Doiron, H.H. Li, and Albert J. Fornace, Jr. (all of Georgetown's Lombardi Comprehensive Cancer Center and the Department of Biochemistry and Moledcular & Cellular Biology); and M.C. Hollander (Center for Cancer Research, NCI, NIH, at Bethesda, Maryland).
In all, much more research will be necessary to access the dangers to astronauts from space radiation as they venture further out into space and as they spend longer periods of time in spacecraft, and on the Moon, Mars, and other solar system bodies.
David Bass
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