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Posts Tagged ‘radiation

Japan postpones removal of Fukushima atomic fuel rods

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The operators of the crippled Fukushima nuclear plant have postponed the extremely complicated and difficult task of removing damaged atomic rods.

New video footage from a robot has revealed new leaks within the damaged reactors meaning the rods now can’t be taken out as planned.

Full Story at: Japan postpones removal of Fukushima atomic fuel rods | euronews, world news

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Written by bothernews

November 17, 2013 at 3:03 pm

Special Report: Help wanted in Fukushima: Low pay, high risks and gangsters

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By Antoni Slodkowski and Mari Saito

IWAKI, Oct 25 (Reuters) – Tetsuya Hayashi went to Fukushima to take a job at ground zero of the worst nuclear disaster since Chernobyl. He lasted less than two weeks.

Hayashi, 41, says he was recruited for a job monitoring the radiation exposure of workers leaving the plant in the summer of 2012. Instead, when he turned up for work, he was handed off through a web of contractors and assigned, to his surprise, to one of Fukushima’s hottest radiation zones.

He was told he would have to wear an oxygen tank and a double-layer protective suit. Even then, his handlers told him, the radiation would be so high it could burn through his annual exposure limit in just under an hour.

"I felt cheated and entrapped," Hayashi said. "I had not agreed to any of this."

When Hayashi took his grievances to a firm on the next rung up the ladder of Fukushima contractors, he says he was fired. He filed a complaint but has not received any response from labor regulators for more than a year. All the eight companies involved, including embattled plant operator Tokyo Electric Power Co, declined to comment or could not be reached for comment on his case.

Out of work, Hayashi found a second job at Fukushima, this time building a concrete base for tanks to hold spent fuel rods. His new employer skimmed almost a third of his wages – about $1,500 a month – and paid him the rest in cash in brown paper envelopes, he says. Reuters reviewed documents related to Hayashi’s complaint, including pay envelopes and bank statements.

 

FULL STORY:  Special Report: Help wanted in Fukushima: Low pay, high risks and gangsters: Scientific American

Written by bothernews

October 27, 2013 at 12:45 am

Neural stimulation with optical radiation

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Neural stimulation with optical radiation.

Laser Photon Rev. Author manuscript; available in PMC 2012 October 16.

Claus-Peter Richter,1,3,* Agnella Izzo Matic,1,2 Jonathon D. Wells,4 E. Duco Jansen,5 and Joseph T. Walsh, Jr.2

Published in final edited form as:
Laser Photon Rev. 2011 January 1; 5(1): 68–80.
Published online 2010 June 7. doi: 10.1002/lpor.200900044
PMCID: PMC3472451
NIHMSID: NIHMS404629

Introduction
Pulsed mid-infrared lasers have been suggested as a method for neural stimulation [13]. The use of lasers has several appealing features when compared to electrical stimulation: no direct contact is necessary between the stimulating source and the tissue, fine spatial resolution of stimulation can be achieved, no stimulation artifact is generated to deter simultaneous recording of electrical responses from the neurons, and there is no electrochemical junction between the stimulation source and the tissue. Furthermore, at many of the radiation wavelengths used for infrared neural stimulation (INS), the radiation can be easily coupled to an optical fiber. Limitations of INS relate to the laser–tissue interaction. Irradiation of tissue with infrared wavelengths will result in a transient temperature increase, which can cause thermal tissue damage. Although it was possible to stimulate auditory neurons through thin bony structures in the cochlea, thick absorbing or scattering layers above the target structure may prevent neural stimulation.
2. Optical stimulation of neurons
…Neural stimulation may also occur via a photochemical reaction, which is initiated by the absorption of the radiation energy…
Photochemical neural activation can also involve the addition of a “caged” molecule that is released upon irradiation. Caged molecules are molecules that were rendered inert by chemically modifying the structure of a bioactive molecule. Irradiation transforms and/or cleaves the caged molecule to restore the biological activity, which is commonly referred to as “photorelease” or “uncaging” [22]. The resulting active molecules can be agonists or antagonists. Thus, photolysis of caged compounds is a method for using light to switch biological processes on or off…
…The authors suggested that the primary mechanism of stimulation was a thermal effect from the laser. Furthermore, they demonstrated that all of the laser-stimulated neurons were sensitive to capsaicin, which binds to a temperature-sensitive ion channel…
3. Neural stimulation with a pulsed infrared laser
3.1. Stimulation of peripheral nerves
…The upper limit for the repetition rate that ensures nondamaging laser stimulation in peripheral nerves occurred near 5 Hz. The maximum duration for constant low repetition rate stimulation (2 Hz) was approximately 4 min with adequate tissue hydration [50]. Note, these results differ from the findings for the auditory nerve (see below for details)..
3.2. Stimulation of Cranial nerves
3.3. Stimulation of the central auditory system in vivo

Lee et al. [68] have demonstrated that neurons of the central auditory system can be stimulated via INS.

4. Possible mechanisms for optical stimulation of neurons

Although some regimes of optical stimulation occur via photochemical interaction (see earlier sections), it is unlikely that pulsed, mid-infrared lasers, such as the FEL, Ho:YAG, or Aculight diode lasers, evoke neural responses via a photochemical reaction. The individual photon energies emitted by these lasers are significantly lower than the energies required to move an electron to an excited state, as is needed for a photochemical reaction.

 

Read More at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3472451/