Biomedical Engineering Reference
In-Depth Information
accepted that following recombination the photon mean free path
became larger than the Hubble length and that these intergalactic
photonstravelledwithoutinteractionbetweengalacticmasses.Like
theelectronwhosemeanfreepathdiffersmarkedlybetweenmoving
insideatomsandwithinconductorssuchasmetalsthephotonmean
free path can be very different depending on its physical state. SFT
involvesacollisionmechanismwithintheatomwheretwocoherent
photons transit between the electron and the proton. There are an
integer number of collisions each cycle where the mean free path is
the Bohr radius, 0.529
10
−
10
m. As we have seen this leads to an
estimate for the photon mass where the photon can be modelled as
atinyparticlehavingahydrogenicstructure.Itmaybethenthatthe
photonhasbeenspeedingupasevolutionproceededandtheenergy
density withinthe universefell.
Returning to a biological system, as we have seen, it is a red
herring to say that THz fields are required to 'break the DNA bond'.
Much lower energies can perturb cellular structures, for example,
getting the cell to turn on its apoptosis mechanism. Exposure to RF
(100-300 kHz) can be beneficial in treating melanomas and brain
tumours, but in the same way RF might well be causing harm to
growing cells and biologicalsystems.
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1.7 Benefits of EMF Exposure
Over the past three decades there has been a growing consensus
amongstmedicalresearchersthatwhilesomeEMFexposuresmight
be hazardous there are also opportunities that are technological
in nature. While the spectrum of EMFs is wide the main thrust
of this medical research has centred on the ELF band. The ELF
band is of interest because many people live near high-powered
transmission systems, including substations, and they use a range
ofpoweredappliancesintheirhomes.Epidemiologicalresearchhas
revealed risks associated with H fields generated by ELF sources.
Health risks include a wide variety of ills ranging from disruption
of normal circadian rhythms to childhood cancers. One important
study was that of Wertheimer and Leeper, who examined the use
of electrically powered blankets and water beds, finding increased
