Two papers published by an assistant professor at the University of California, Riverside and several collaborators explain why the universe has enough energy to become transparent.
Astronomy
Sep 12, 2016
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1549
(PhysOrg.com) -- At very cold temperatures, in the absence of light, a photomultiplier will spontaneously emit single electrons. The phenomenon, which is called "cryogenic electron emission," was first observed nearly 50 ...
An international team of scientists, including a University of York researcher, has carried out ground-breaking experiments to investigate the atomic structure of astatine (Z=85), the rarest naturally occurring element on ...
General Physics
May 14, 2013
0
1
(PhysOrg.com) -- NASA's Phoenix lander revealed water ice mere inches beneath the martian surface, and chemical evidence from the landing site strongly hints that the region is habitable. But learning whether there is life ...
Space Exploration
Jun 8, 2010
3
0
A team from the University of Illinois at Urbana-Champaign and Northwestern University has devised a novel nuclear magnetic resonance imaging (MRI) technique that delivers a roughly 10-nanometer spatial resolution. This represents ...
General Physics
Sep 27, 2013
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A Northwestern University study shows that coupling a widely used magnetic resonance imaging (MRI) contrast agent to a nanodiamond results in dramatically enhanced signal intensity and thus vivid image contrast. "The results ...
Bio & Medicine
Feb 18, 2010
3
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Sunbathers have long known that melanin in their skin cells provides protection from the damage caused by visible and ultraviolet light. More recent studies have shown that melanin, which is produced by multitudes of the ...
Biochemistry
Aug 23, 2011
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1
Lightning can produce X-rays and gamma radiation. In the past, researchers thought that this phenomenon only lasted for a very short time, about one ten-thousandth of a second. However, the ionizing radiation of lightning ...
Earth Sciences
Oct 24, 2017
0
62
A Northwestern University study shows that coupling a magnetic resonance imaging (MRI) contrast agent to a nanodiamond results in dramatically enhanced signal intensity and thus vivid image contrast.
Bio & Medicine
Jan 14, 2010
1
0
University of Utah engineers designed microscopic mechanical devices that withstand intense radiation and heat, so they can be used in circuits for robots and computers exposed to radiation in space, damaged nuclear power ...
Engineering
Jun 12, 2012
5
0
Ionizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them. The occurrence of ionization depends on the energy of the impinging individual particles or waves, and not on their number. An intense flood of particles or waves will not cause ionization if these particles or waves do not carry enough energy to be ionizing. Roughly speaking, particles or photons with energies above a few electron volts (eV) are ionizing.
Examples of ionizing particles are energetic alpha particles, beta particles, and neutrons. The ability of electromagnetic waves (photons) to ionize an atom or molecule depends on their wavelength. Radiation on the short wavelength end of the electromagnetic spectrum - ultraviolet, x-rays, and gamma rays - is ionizing.
Ionizing radiation comes from radioactive materials, x-ray tubes, particle accelerators, and is present in the environment. It is invisible and undetectable by human senses, so instruments such as geiger counters are required to detect its presence. It has many practical uses in medicine, research, construction, and other areas, but presents a health hazard if used improperly. Exposure to radiation causes microscopic damage to living tissue, resulting in skin burns, radiation sickness and death at high doses and cancer, tumors and genetic damage at low doses.
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