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'[EE] Childhood cancer in relation to distance from'
2005\06\25@000929 by Russell McMahon

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Sometimes y' just gotta do it regardless.
Annoying but ...

Study of 29,081 English/Welsh children with cancer incl 9,700 with
Leukaemia to check correlation with distance from power lines at time
of birth.

Significant risk factor increase (1.69 times) found for children
living withing 100 metres of power lines.

British Medical Journal.

       http://bmj.bmjjournals.com/cgi/content/full/330/7503/1290?ehom

The publication of this study has been long delayed. It was originally
funded by a power industry source. Reasons for late release are not
known with certainty.

Do note that mechanism involved is not claimed to be known and the
result *may* be due to 'confounding factors'.



           RM
_______________________________________

EXCERPTS


RESULTS

Results Compared with those who lived > 600 m from a line at birth,
children who lived within 200 m had a relative risk of leukaemia of
1.69 (95% confidence interval 1.13 to 2.53); those born between 200
and 600 m had a relative risk of 1.23 (1.02 to 1.49). There was a
significant (P < 0.01) trend in risk in relation to the reciprocal of
distance from the line. No excess risk in relation to proximity to
lines was found for other childhood cancers.

What this study adds

A UK study of 29 000 cases of childhood cancer, including 9700 cases
of leukaemia, found a raised risk of childhood leukaemia in children
who lived within 200 m of high voltage lines at birth compared with
those who lived beyond 600m (relative risk 1.7)

Conclusions

There is an association between childhood leukaemia and proximity of
home address at birth to high voltage power lines, and the apparent
risk extends to a greater distance than would have been expected from
previous studies. About 4% of children in England and Wales live
within 600 m of high voltage lines at birth. If the association is
causal, about 1% of childhood leukaemia in England and Wales would be
attributable to these lines, though this estimate has considerable
statistical uncertainty. There is no accepted biological mechanism to
explain the epidemiological results; indeed, the relation may be due
to chance or confounding.
There was also a slightly increased risk for those living 200-600 m
from the lines at birth (relative risk 1.2, P for trend < 0.01); as
this is further than can readily be explained by magnetic fields it
may be due to other aetiological factors associated with power lines
___________________________


Childhood cancer in relation to distance from high voltage power lines
in England and Wales: a case-control study
Gerald Draper, honorary senior research fellow1, Tim Vincent, research
officer1, Mary E Kroll, statistician1, John Swanson, scientific
adviser2
1 Childhood Cancer Research Group, University of Oxford, Oxford OX2
6HJ, 2 National Grid Transco plc, London WC2N 5EH
Correspondence to: G J Draper spam_OUTgerald.draperTakeThisOuTspamccrg.ox.ac.uk

2005\06\25@012403 by Robert Rolf

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Wireless World magazine had a good analysis of the analysis
back in the late '80s when this was a really hot topic.

It's not the EM that is the problem. It's the way the
magnetic field ends up concentrating cosmic rays
under the power lines. Think cylindrical lens.
Detection rates for cosmic rays were several times
higher under the power lines and lower in the region
immediately outside the towers.

I always get a little peeved when people complain
about EM from power grids. The nerve cells in our bodies
have membranes that are tiny (u inches) and voltages that
are small(10's or 100's of mV (nerve/muscle)) but
work out to 10's to 100's of KILOVOLTS per meter.
Compared to what our body is generating internally,
external EM is buried in the noise. If it weren't
we'd all be twitching whenever our cell phones were
operating.

On a similar vein, some 1980's study found that women who
used electric blankets had higher rates of miscarriage.
Of course the authors forgot to check on whether
being hot while you slept was a contributing factor.
A later study found that sleep temperature had a stronger
correlation. But by then the damage had been done and
manufactures had to produce 'low emission' electric
blankets. (just have the heating wire double back on
itself so that the magnetic fields canceled.

Just my few billion electrons worth.

Robert
(who works in Neuroscience, so I've been well overexposed
to the details. e.g. trying to record tiny nerve signals
which are swamped by muscle electrical signals).

Russell McMahon wrote:

{Quote hidden}

2005\06\25@023839 by Luis.Moreira

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Yes,yes,yes, this is the same as the mobile phone masts, they will be
starting to knock them down to soon.
I sough a program about the risk of the mobile phones here in the UK and it
was great. There was a lady that was sold a "radio wave concentration
detector", which for me looked like a radio receiver tuned to the mobile
phone frequency with a speaker, it also seamed to have a sort of directional
antenna. So this lady showed the reporter How High the "concentration of
radio waves" in her house was because the "expert that sold her the
"detector" made a study and the way her house was configured and the shape
of the land was "trapping" the waves in her house. Someone just made a lot
of money from scaring the hell out of this people... Let's face it a box
that as written on it Radio Wave detector, a mobile phone mast and a speaker
set to very loud, cracking away and an Expert saying to you that your house
is a radio wave concentrator, come on you would think you are going to die
soon. Nice earner I think is just a pity that I did not have the idea.
For people like me this will just mean, ok research is needed, for normal
people this will mean I live by a pylon so I will die.
This reminds me of the millennium Bug, some people made a lot of money...
Regards
       Luis


{Original Message removed}

2005\06\25@032747 by Russell McMahon

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**** Please answer this offlist ****
**** Please answer this offlist ****
**** Please answer this offlist ****
**** Please answer this offlist ****

Someone opined that I should have used [OT] for this post.
This seemed to me like the sort of thing that I was being told should
be on [EE].
What think you all?


           RM

2005\06\25@032748 by Russell McMahon

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> Yes,yes,yes, this is the same as the mobile phone masts, ...

Don't let the fact that their are charlatans abroad blind you to
reality.

[Read | Did you read] the paper or its summary?

       http://bmj.bmjjournals.com/cgi/content/full/330/7503/1290?ehom

Note the organisation, the journal publishing the paper, the sample
size and note their methodology. They may have got it wrong. But it
seems than did an OK job.

A key point IMHO is that they found a 1.7 times childhood Leukaemia
rate increase but no statistically significant changes for any other
type of cancer.

       RM

2005\06\25@032755 by Russell McMahon

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Sumimasen:

> Wireless World magazine had a good analysis of the analysis
> back in the late '80s when this was a really hot topic.
>
> It's not the EM that is the problem. It's the way the
> magnetic field ends up concentrating cosmic rays
> under the power lines. Think cylindrical lens.
> Detection rates for cosmic rays were several times
> higher under the power lines and lower in the region
> immediately outside the towers.

Alas, it's not that simple.
I've been watching this area for several decades and noting the
numerous studies which "prove things conclusively" from both sides.
There is NO single mechanism that does a good job of providing a
plausible explanation and few results, positive or negative, which
stand up to intensive scrutiny or repeatability.

IF there is an EM fields related damage mechanism, or a number of
them, they are close to being down in the noise. That doesn't mean
they should be dismissed or not looked for. An effect may cause
substantial damage and even loss of life and be hard to detect because
it ony occurs in selected environments. Saving perhaps hundreds of
lives a year MAY be cheap and easy if you can ever determine what the
effect is.

I posted this study because it was by a reputable organisation and had
a large user base and seemed well enough designed and targeted to be
worth thinking about. They note that while they believe theeffect to
be real they do not know the mechanism and note that it may be due to
confounding factors. "Above all, do no harm" should be as much a
requirement of our profession as for others.

AFAIR the cosmic ray lensing effect, which seemed to offer a very nice
explanation of the problem, did not stand up to extended scrutiny. If
this mechanism is a real one then it would be a very good explanation
of how non-ionising ratiation can cause cell destruction. The fact
that this theory was well known and that areas along either side of
transmission lines are now not bare earth suggests that the theory
failed the test of full investigation. Even vested intetest from power
utilities only foes so far.

> I always get a little peeved when people complain
> about EM from power grids. The nerve cells in our bodies
> have membranes that are tiny (u inches) and voltages that
> are small(10's or 100's of mV (nerve/muscle)) but
> work out to 10's to 100's of KILOVOLTS per meter.
> Compared to what our body is generating internally,
> external EM is buried in the noise. If it weren't
> we'd all be twitching whenever our cell phones were
> operating.

The *mechanism* is not important. It's whether there *is* a
correlation. If we classify things which we don't understand to the
same category as the waving of dead fish, because we haven't enough
imagination or luck to ascertain the mechanism we may miss out badly.
Explaining how something doesn't work has little point if it does
achieve the tesult by some other means.

In a related field:
In Sellafield / Windscale there have been a number of concentrations
of childhood cancer very significantly in excess of the statistically
expected average and dissimilar to what is seen anywhere else in the
UK. Careful radiation studies have shown that there have been no
increased radiation levels or other factors relating to the town's
nuclear fuel reprocessing plant. so it is clear that these are just
"bad luck" and they don't need to look further into the safety issues
at the reprocessing plant. If you believe that line you can probably
get a nice job at the plant and assisted passage, along with your
family.




           RM










{Quote hidden}

> --

2005\06\25@045247 by Lindy Mayfield

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Does it have any meaning, in anyone's opinion, that the frequency of cell phones is quite near microwaves in the spectrum?  I just thought, if microwaves can jiggle atoms and make water boil, then perhaps something near like a cell phone can jiggle stuff and after a lot of exposure then why wouldn't things maybe go wrong?

{Original Message removed}

2005\06\25@053708 by Luis.Moreira

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Hi Lindy
That lady also thought that the radio waves were getting trapped in her
house and were accumulating in her room. That was not true, it was just
something someone told her. Your theory is good but did you see any research
that said that did happen? Did someone exposed living tissue to radio waves
(mobile phones) and found that it alter the structure of the cells?
Probably not but some people will still see it as a true statement and act
on it. Specially if you been affected by it, i.e. a loved one gets a illness
that can be linked to the Mobile phone mast or the power lines.
Regards
       Luis

 



{Original Message removed}

2005\06\25@070212 by Wouter van Ooijen

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> I've been watching this area for several decades and noting the
> numerous studies which "prove things conclusively" from both sides.
> There is NO single mechanism that does a good job of providing a
> plausible explanation

I don't want to argue for any viewpoint in this discussion, but note
that the fact that no good explanation exists for an observation can of
course not be used as argument against that observation!

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2005\06\25@070443 by dr. Imre Bartfai

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Hi,
there is NOTHING new in the topic. Nancy Wertheimer has concluded the same
results AFAIK in Denver. She has published with Leeper at late '70s. Even
theoretical evidence exist on cell level that 50cps facilitates the
generation of HSP-72, which restarts in turn the cell proliferation.

I measured some days ago directly under a H/V power line and found 3kV/m
(!!!) and 1000nT. I had a fear I must confess... Vary researchers say
there is no place to anxiety under 20nT.

I was called to a residence very at the said line and found in the house
up to 300nT. The housewife has complains which I would explain as EHS
syndrome (electrical hypersensitivity). It is a very interesting
phenomenon which says there are people who have health problems in the
presence of electromagnetical fields even others have not. It was shown by
means of a lot of double-blind studies it is not a placebo effect. I think
if EHS would be considered then a lot of seemingly contradiction would be
resolved.

Regards,
Imre



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2005\06\25@074451 by Gerhard Fiedler

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Lindy Mayfield wrote:

> Does it have any meaning, in anyone's opinion, that the frequency of cell
> phones is quite near microwaves in the spectrum?  

Also, look at the money involved. This are many billions of
dollars/euros/whatever, with governmental agencies and big multi-national
companies involved. They have both the power and the interest to severely
alter the type of much of the research being done and how the results are
being published.

So whatever you /think/ you /know/, unless you have your own funds and the
time to dedicate to really independent research, it's probably based on
research done by others. Who mostly are somehow involved with the above
interests.

As a scientist, you should know that the potential knowledge is infinite,
our current knowledge is finite, and thus infinitely small -- and this will
never change :)  

Gerhard

2005\06\25@080540 by Russell McMahon

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>> I've been watching this area for several decades and noting the
>> numerous studies which "prove things conclusively" from both sides.
>> There is NO single mechanism that does a good job of providing a
>> plausible explanation

> I don't want to argue for any viewpoint in this discussion, but note
> that the fact that no good explanation exists for an observation can
> of
> course not be used as argument against that observation!

I agree - I was trying to put both sides of the position at once and
did a poor job of it.

As I have noted, I also do not hold strongly to one side or other of
the argument. As I said - IF there are mechanisms that cause problems
then they must overall produce results near the noise level. This
COULD mean that they don't exist. Or it could mean that they probably
do not act the same in all circumstances and the overall result is low
statistically. If they could be isolated they may be significant - if
they exist :-). As an example, the current survey relates to Leukaemia
for children born within 100 metres of ?major? power lines. Based on
my own measurements both in the past and for someone as recently as
today, that is a VERY poor measure if direct EM interaction is the
culprit as the field is very very very substantially reduced at 100
metres.  "Living in a house which is partially under the power wires"
would be a better test. Then there may be a genetic predisposition to
this effect which appears only in some children and serves to further
dilute the results. And there may even be dietary or environmental
factors which increase or decrease the risk. Or the whole result, if
real, as it appears to be, could be caused by a non EM factors. eg
power lines may tend to be on average closer to main roads than the
average residence, where vehicle fumes could cause problems. etc.

The result may well be a genuine one.
The reason should be worth looking for but MAY not relate to the power
lines directly.


       RM

.

2005\06\25@204112 by Richard Prosser

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EE.

Richard P

On 25/06/05, Russell McMahon <.....apptechKILLspamspam.....paradise.net.nz> wrote:
{Quote hidden}

> -

2005\06\25@224147 by Mario Mendes Jr.

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My solution to this problem is to wear a tin-foil hat 24x7.  Seems to be
keeping the government from getting to my thoughts, at least they
haven't come knocking on my door yet ;^)

In the next few months you'll see another study that says the opposite
of what this one does.


-Mario

{Original Message removed}

2005\06\25@224816 by Stephen R Phillips

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--- Russell McMahon <EraseMEapptechspam_OUTspamTakeThisOuTparadise.net.nz> wrote:

> The result may well be a genuine one.
> The reason should be worth looking for but MAY not relate to the
> power
> lines directly.
>
>
One thing that I've noticed is that in the past some power companies
used certain chemical substances along power lines to reduce the amount
of 'clearing' they need to keep trees etc from growing beneath them.
In 1981 a power company used essentially agent orange (it was agent
orange actually just a different concentration than they used in
vietnam) as a defoilient in my area around power lines.  That year my
fathers farm experienced 10 still births 3 dead animals (the herd was
young and the deaths were quite mysterious). This is above the normal
for that area (whatever normal is).  I myself a year and a half later
became diabetic.  I doubt the power lines had diddly to do with those
problems.  We moved away in 1982 in any case and I was diagnosed as
having type 1 diabetis.  Related or not, none of my relatives have been
diagnosed as diabetic, ever.

So really the probability is high that anything they might have used to
suppress brush or in construction etc. near the power lines is likely
to have increased this risk more than anything.  I think people tend to
be careless about how they use things in general.

This isn't an arguement it's just a note that this is more likely the
cause then high voltage EMF waves. :)



Stephen R. Phillips was here
Please be advised what was said may be absolutely wrong, and hereby this disclaimer follows.  I reserve the right to be wrong and admit it in front of the entire world.

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2005\06\25@234949 by Dave VanHorn

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I was thinking on this lensing effect a bit.

With an AC line, the magnetic field spends half it's time in each
state, so in the end, everything should average back to what it was
before, right?
Further, with closely spaced lines running as a balanced pair, or
three phase triplet, the field should be relatively small outside a
relatively short distance.


Maybe the real relation is something else that correlates to not
being able to afford the houses farther away from the powerlines.

2005\06\26@003242 by Mario Mendes Jr.

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> Maybe the real relation is something else that correlates to not
> being able to afford the houses farther away from the powerlines.

I see what you're saying.  Then a study on people with similar life
styles but away from power lines should have comparable results.

-Mario


2005\06\26@020042 by Russell McMahon

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This

> My solution to this problem is to wear a tin-foil hat 24x7.  Seems
> to be
> keeping the government from getting to my thoughts, at least they
> haven't come knocking on my door yet ;^)

and this

> In the next few months you'll see another study that says the
> opposite
> of what this one does.

sort of approach puts you at risk of missing any useful truths that
MAY be present.

I'll only address the second point. There are many studies and while
many appear to demonstrate correlation between EM fields and certain
diseases, there are many which can find no correlation.

It is useful to consider the sample size (bigger is better), the
reputability of the researchers and the methodologies used. In this
case the study APPEARS, at first glance, to be a high quality one.
Sample size is extremely large. Primary data sources include numerous
other smaller trials so one can expect that a fundamental flaw in the
sampling methods is less likelier than for a single group study.

There is another significant factor. While they looked at correlations
between power line distance and a number of childhood cancers they
only found a correlation with Leukaemia. It seems very likely that
SOMETHING related to power lines increases the incidence of childhood
Leukaemia. Occam's Razor says its the power lines themselves.
Experience says it MAY be something else instead. Could be weed spray
used under lines, roadway proximity, lower socio economic groups buy
into power line affected areas, etc.

So, while there may indeed be another contrary study in the next few
months that APPEARS to contradict this one, you would have to
determine that it met the (apparent) quality of this one before you
were able to consider that they "cancelled each other out."


       RM






2005\06\26@080806 by olin piclist

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Russell McMahon wrote:
> It seems very likely that
> SOMETHING related to power lines increases the incidence of childhood
> Leukaemia. Occam's Razor says its the power lines themselves.

I totally disagree with this.  Even if you take the study at face value and
say there is indeed a correlation between leukaemia and proximity to power
lines, there is no basis for claiming it's the power lines directly.  There
are many other things correlated to proximity to power lines which all need
to be controlled for to rule them out.  Even then, it would not prove it's
the power lines themselves, only that it is not one of the factors
controlled for.

Without good evidence of a mechanism, any claim of the cause is just a
guess.  Others have already pointed out defoliants and economic level.  I
think both of these are way more likely related to be the cause than EM
fields from power lines at over 100 meters distance.  But of course that's
just speculation too.


*****************************************************************
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(978) 742-9014, http://www.embedinc.com

2005\06\26@082715 by Lindy Mayfield

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My mobile stays charging on my desk where I have speakers and usually listen to online radio.  

Every few hours seemingly at random, or before I get a call, I can hear quite well a recurring pattern and rhythm:  

Da-da dot da-da dot da-da dot da-da dot

The tone is around 200 Hertz (somewhere about a D above middle C).  

It seems this little thing puts out a lot of power to affect the speakers like this.  I'm not saying it is scrambling my brain or making me yell at the cat, but I do wonder what is going on there.

{Original Message removed}

2005\06\26@084754 by Jan-Erik Soderholm

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Lindy Mayfield wrote :

> Every few hours seemingly at random, or
before I get a call,
> I can hear quite well a recurring pattern and
rhythm:  
>
> Da-da dot da-da dot da-da dot da-da dot

You can probaly
hear the same kind of sounds right after
turnon or before turnoff when
your mobile is "talking"
with "your" current base station. Or when
someone calls
you, or when your mobile switches from one base
station
to another (such as in the car).

> It seems this little thing puts out
a lot of power to affect
> the speakers like this.
> I'm not saying it
is scrambling my
> brain or making me yell at the cat, but I do wonder
what is
> going on there.

It's only "traffic" between your
mobile and
the base station.

Regards,
Jan-Erik.



2005\06\26@094618 by Jinx

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>
> Every few hours seemingly at random, or before I get a call, I can
> hear quite well a recurring pattern and rhythm:  
>
> Da-da dot da-da dot da-da dot da-da dot

It's the exchange talking to your phone. I'm in a project with a Nokia
site engineer and he explained why my phone does it. IIRC if the
exchange doesn't hear from the phone for a certain period, it pings it
to find out if it's been turned off

When it happens here, any sleeping PCs wake up, and on one in
particular the mouse pointer moves about an inch to the left in tiny
hops !! The tone doesn't get into the PC through the audio lines
though, as occassionally it'll happen whilst I've been recording music
from an external source but the phone sound never gets recorded

2005\06\26@130531 by Jim Korman

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Lindy Mayfield wrote:
> My mobile stays charging on my desk where I have speakers and usually listen to online radio.  
>
> Every few hours seemingly at random, or before I get a call, I can hear quite well a recurring pattern and rhythm:  
>
> Da-da dot da-da dot da-da dot da-da dot
>
> The tone is around 200 Hertz (somewhere about a D above middle C).  
>
> It seems this little thing puts out a lot of power to affect the speakers like this.  I'm not saying it is scrambling my brain or making me yell at the cat, but I do wonder what is going on there.
>
I get something similar to that when my DSL router is negotiating
with our provider. Checked it by looking at the DSL logs.

Jim

2005\06\26@160314 by Robert Rolf

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Major power lines are usually three phase so there is
never an aggregate 'null' field. On the larger scale magnetic lens
created by the three currents effectively moves and forth across
the width of the tower as the AC cycle progresses. (Superposition)
Yes, for any particular particle track and a single wire
there is a 50% probability that it would be bent toward
as house as likely as being bent away, but gamma rays tend
to come it clusters (gamma ray bursters), so at a given
moment, the lenses could significantly increase the
level of ionizing radiation to the point where it can
cross the threshold of damage (e.g. breaking DNA bonds).

It would be interesting to model the EM field in a good
EM  modeling program.

Dave VanHorn wrote:

{Quote hidden}

Likely as not. You have to control for ALL possible variables
before you can draw an irrefutable conclusion.
And knowing the mechanism for action would help.

Some time in the mid nineties I saw a report that claimed
higher leukemia rates in children who watched a lot of television.
Big screen CRT's emit a LOT of EM so maybe there is an
influence, but why do the rats/rabbits/ being exposed to
very high EM levels in EM research projects not get leukemia?

Robert

2005\06\26@230405 by Chen Xiao Fan

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On a side note, how many young engineer know how to calculate the
EM field near high voltage transmission line? Not many as far as I know,
at least in USA (maybe I am not qualified to I say that and sorry to
those who are in USA and know the calculation), especially after
they dissolved a lot the electric power engineering programs in
the universities. How could they know since quite some students
did not know how to connect a dual 0-30V DC power supply to generate
a 40V DC voltage (do not laugh, this is my real experience in a
top 50 US university as a TA in a senior class, it is not RPI though)?

I admit I did not know how to do it either until I took the course from
Professor Nelson in RPI some years back, that is one of the best EM
course I ever had. If you know how to calculate, you will not blame
the transmission line but seek other reasons.

regards,
Xiaofan

-----Original Message-----
From: Robert Rolf [Robert.Rolfspamspam_OUTualberta.ca]
Sent: Monday, June 27, 2005 5:00 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Childhood cancer in relation to distance from high
voltagepower lines in England and Wales: a case-control study

...
It would be interesting to model the EM field in a good
EM  modeling program.
...

2005\06\27@030125 by Russell McMahon

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> If you know how to calculate, you will not blame
> the transmission line but seek other reasons.

You need to be careful when forming conclusions like that that you
don't blind your selves to real but unvisualised effects - either
direct or second order.

You are correct in suggesting that the EM fields generated by a power
line decay rapidly away from the line and at a few tens of metres
field strengths from normal house wiring and appliances will dominate.
(Wandering around the area under a High Voltage  power line and
through a normal house with a field strength meter (as I was doing a
few days ago) can be an interesting exercise.

BUT

Firstly " ... will not blame the transmission line ... " suggests that
the observed Leukaemia increase in the proximity of power lines does
not exist, regardless of reason. As discussed by several people, it
MAY be that the effect is real but is related to some indirect cause
such as use of herbicides along power line routes, increased traffic
compared to average levels along power lines, socio-economic effects
that leading to it being more likely that people living close to power
lines are on average of lower income. There may be a lensing of cosmic
radiation (as proposed some  decades ago). etc. Some of these would
still lead us to "blame the transmission line". ie if it had never
been built the weedkiller would not have been used and the lensing
would not occur. These cases have in common that the EM field does not
directly interact on the persons concerned.

Then there is the POSSIBILITY that the sheer physical scale of the
field has some effect. As an example of scale versus magnitude, note
that you can produce laboratory magnets with fields vastly in excess
of the earth's field - but they are for practical purposes
undetectable a few tens of metres away. However, the earth's magnetic
field is detectable worldwide. The reasons are obvious enough and not
at all unexpected but the implications are significant - you can't
expect to swing all the magnetic compasses on earth using a lab
magnet, no matter how strong.

In the case of transmission lines we have an essentially infinitely
long field of roughly circular cross section. If there are 3 phases
they are probably arranged to change in position over significant
distance to average capacitance to ground but over a distance of some
spans you may well have a fixed pattern on the poles. This will lead
to a large "rolling" cylinder of electromagnetic field sweeping across
the ground in the same direction consistently. This is liable to be
quite different from the pattern experienced with similar level fields
in a domestic environment. (I presently appear to have a "split phase"
in my kitchen-dining area and the EM field due to house wiring is in
excess of that under the local 220 kV power lines. This does NOT mean
that the EM field in my kitchen has the same effects as those for
house located under the power lines. For practical purposes i consider
that the direct EM effects of a significant power line are liable to
be confined inside a strip extending a few 10's of metres outside the
projection of the outer power line wire.

Leukaemia, unlike any other cancer that I am can think of, affects a
fluid distributed all around the body with all of it being very near
the body surface for some of the time. If one was to look for a prime
candidate for the effects of low level rotating fields blood would be
a good first guess.

So, it MAY be that the physically large infinitely long rolling
cylinder of EM field has some subtle interactions with blood which are
not significant for higher randomly oriented single phase fields. And
it may not. But it would be unwise in the extreme to simply conclude
".. not blame the transmission line ..." when a 1.7 times correlated
increase in infant leukaemia has been demonstrated by a VERY large
scale study by a reputable organisation. A properly conducted survey
of 9,000 odd sample size has a margin of error of about 0.1%.  And not
a tinfoil hat in sight !!! (or a dead fish).


       RM





2005\06\27@031635 by Russell McMahon

face
flavicon
face
> Russell McMahon wrote:
>> It seems very likely that
>> SOMETHING related to power lines increases the incidence of
>> childhood
>> Leukaemia. Occam's Razor says its the power lines themselves.

And Olin inexplicably responded
{Quote hidden}

You may, perhaps, be unfamiliar with the concept of Occam's razor, and
you may, perhaps, have not read the concusions or abstract of the
report you are commenting on?

Occams's razor is the proposition that, given several potentially
equally plausible explanations, the simplest should be preferred.
Originally stated as "Pluralitas non est ponenda sine neccesitate" or
"plurality should not be posited without necessity."

You truncated what I said in mid quote and thereby radically altered
it's meaning. I said -

   It seems very likely that SOMETHING related to power
   lines increases the incidence of childhood Leukaemia.
   Occam's Razor says its the power lines themselves.
   Experience says it MAY be something else instead.
   Could be weed spray used under lines, roadway
   proximity, lower socio economic groups buy into
   power line affected areas, etc.

We are in fact in reasonably close agreement. And the authors of the
report do not disagree with you in general terms. They said, as I
quoted in my original post:

   There is no accepted biological mechanism to explain
   the epidemiological results; indeed, the relation may
   be due to chance or confounding.

and they also said

   There was also a slightly increased risk for those
   living 200-600 m from the lines at birth
   (relative risk 1.2, P for trend < 0.01); as this is further
   than can readily be explained by magnetic fields it
   may be due to other aetiological factors associated
   with power lines.

They are being purposefully extremely 'cagey' with their comments, yet
most people who have commented here have either been drivelling on
about tinfoil hats and blinding themselves to the possibility of
something of real concern here) or rejecting conclusions that the
original report does noty draw.

> Without good evidence of a mechanism, any claim of the cause is just
> a
> guess.

And they make none.

> Others have already pointed out defoliants and economic level.  I
> think both of these are way more likely related to be the cause than
> EM
> fields from power lines at over 100 meters distance.  But of course
> that's
> just speculation too.

Indeed. And this has been discussed at some length. But I don't recall
one post that said anything like -

       "Wow! 1.7 tomes. That's statistically huge! And odds are the
people at from 50m to 100m out are not affacted much if at all, so
that suggests the real effect  is being hidden and it may be a factor
of 5 or 10 or even more in some cases. And many people wouldn't live
around power lines forever, and some at least would be partially
screened and .... so the real effect is probably only acting on a
small part of the sample - so it must be even bigger than we
expected."

Instead, the tinfoil hats seem to win the day.

Sad.


       RM

2005\06\27@034412 by William Chops Westfield

face picon face
On Jun 27, 2005, at 12:16 AM, Russell McMahon wrote:

> [that noone has said:] "Wow! 1.7 times. That's statistically huge!..."

I don't know enough about statistics to evaluate the results of the
study.
Out of 29081 children with cancer, there were 64 cases of leukemia from
people who lived less than 200m from (mostly) 275 and 400kV overhead
lines
WHEN THEY WERE BORN, compared to only 39 in control cases.  Their table
certainly looks interesting, especially since things even out so nicely
for larger distances and other diseases, but 100 cases is still a very
small number to be doing statistics on.  And that "when they were born"
thing really bugs me too, since at least in the US it is very common
to move shortly after the birth of your first child...

It's a shame that it is so nearly impossible to conduct research on
human problems without running into "politics" (in the large sense.)

BillW

2005\06\27@080829 by olin piclist

face picon face
Russell McMahon wrote:
> Occams's razor is the proposition that, given several potentially
> equally plausible explanations, the simplest should be preferred.

Right.  The problem then becomes deciding the simplicity of the various
alternatives.  I was objecting to the implied assumption in your statement
that the power lines themselves causing the correlation was the simplest
explanation.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\06\27@083326 by Wouter van Ooijen

face picon face
> > Occams's razor is the proposition that, given several potentially
> > equally plausible explanations, the simplest should be preferred.
>
> Right.  The problem then becomes deciding the simplicity of
> the various
> alternatives.  I was objecting to the implied assumption in
> your statement
> that the power lines themselves causing the correlation was
> the simplest
> explanation.

Even when Occam would vote for a particular explanation for a phenomenon
one should remember that 'Occams razor' is a principle, not an absolute
truth.

My debugging experience shows that after maybe an hour of debugging it
is not a good idea to search for yet another 'simple' cause for your
systems' malfunctioning. By then the cance is almost 100% that the cause
is either a complex one, or a mix of more than one simple causes. Occam
would stil vote for one simple cause.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2005\06\27@085950 by Russell McMahon

face
flavicon
face
>> > Occams's razor is the proposition that, given several potentially
>> > equally plausible explanations, the simplest should be preferred.

> Even when Occam would vote for a particular explanation for a
> phenomenon
> one should remember that 'Occams razor' is a principle, not an
> absolute
> truth.

Agreed.
As I said originally (approx)
OccamsRazor suggests ...
Reality suggests ...

But even that is in agreement with OR.
You start with the simplest reason.
As things progress without success the simple reqsons become
manifestly inadequate and are no longer 'equally plausible". Odds are
that you then don't choose the most unlikely and convoluted possible
reason but again choose the simplest that may make sense.

That;s why it takes a long time to arrive at the real reason, which is
often unlikely and convoluted ;-)



       RM

2005\06\27@085954 by Russell McMahon

face
flavicon
face
It would be greatly appreciated (and not just by me) that any comments
on this thread involving tinfoil hats, black helicopters and their ilk
get posted to OT rather than EE.

Table of calculated magnetic fields produced by underground cables in
operation in the UK

       http://www.emfs.info/Source_underground_mag_fld_table.asp

Tables of calculated electric fields produced by overhead lines in
operation in the UK

       http://www.emfs.info/Source_elec_fld_table.asp

Typical ground-level UK field levels from overhead power lines

       http://www.emfs.info/Source_overhead.asp#uk

These pictures show the field lines produced by typical transmission
lines. The field lines are calculated for the instant in time when the
current and voltage on the middle phase is zero. [[They don't comment
on the "sweeping effect which I imagine exists in the time variant
pattern.]]

       http://www.emfs.info/Source_transmission_fieldlines.asp

Note the double lobe shape withj some systems. Match (very probably
coincidentally) the double maximam of the cancer survey which appears
to occur at some distance from the pole centre line.



           RM

2005\06\27@091333 by Dave VanHorn

flavicon
face
At 07:55 AM 6/27/2005, Russell McMahon wrote:
>It would be greatly appreciated (and not just by me) that any
>comments on this thread involving tinfoil hats, black helicopters
>and their ilk get posted to OT rather than EE.
>
>Table of calculated magnetic fields produced by underground cables
>in operation in the UK
>
>        http://www.emfs.info/Source_underground_mag_fld_table.asp
>
>Tables of calculated electric fields produced by overhead lines in
>operation in the UK

Homes by HelmHoltz?

You live in a field that's far larger, at about 25-50uT, and you
fearlessly walk around changing the polarity willy nilly, with total
disregard for the consequences.


2005\06\27@095511 by Howard Winter

face
flavicon
picon face
Lindy,

On Sat, 25 Jun 2005 10:51:44 +0200, Lindy Mayfield wrote:

> Does it have any meaning, in anyone's opinion, that the frequency of cell phones is quite near microwaves in
the spectrum?  I just thought, if microwaves can jiggle atoms and make water boil, then perhaps something near
like a cell phone can jiggle stuff and after a lot of exposure then why wouldn't things maybe go wrong?

When I got my first mobile phone, which was a model known for having a high RF output level, I found that if I
used it on my right ear my right eye would start to hurt (no, I wasn't poking myself in the eye with the
aerial! :-) so I used it on my left ear instead, which didn't cause any problems.  I don't know why it
happened, but it convinced me to use mobile phones as little as possible!

Cheers,


Howard Winter
St.Albans, England


2005\06\27@095922 by Howard Winter

face
flavicon
picon face
Luis,

Water-heating properties of mobile phones...

On Sat, 25 Jun 2005 10:36:51 +0100, Luis Moreira wrote:

> That lady also thought that the radio waves were getting trapped in her
> house and were accumulating in her room. That was not true, it was just
> something someone told her. Your theory is good but did you see any research
> that said that did happen?

Absence of research showing that something is dangerous doesn't make it safe!

When I was a child shoe-shops had X-Ray machines into which you could place your feet and see how your shoes
fitted... my mother told me to "stay away from them, they're dangerous".  That wasn't a researched fact, but
we now know it to be true...

Cheers,


Howard Winter
St.Albans, England


2005\06\27@102352 by Howard Winter

face
flavicon
picon face
Dave,

On Sat, 25 Jun 2005 22:49:54 -0500, Dave VanHorn wrote:

>
> I was thinking on this lensing effect a bit.
>
> With an AC line, the magnetic field spends half it's time in each
> state, so in the end, everything should average back to what it was
> before, right?

Wrong!  Does a lightbulb running on AC produce no light on average?  Does an AC motor not move because it just
oscillates with the phase reversals?  If the power lines are acting as a lens for cosmic rays, the fact that
it's AC may mean that it has a "sweeping" effect, with the focussed rays moving back and forth under the
lines, but it depends on the line geometry.  Most UK National Grid pylons have six wires strung from them in
two roughly-vertical sets of three, which I believe is one set of 3-phase on each side.  Whether the
horizontal pairs are the same phase I don't know.

> Further, with closely spaced lines running as a balanced pair, or
> three phase triplet, the field should be relatively small outside a
> relatively short distance.

The ones we're discussing are certainly 3-phase - and I don't know what you call a short distance, but walking
under a 133kV line that crosses the road about a mile from here in wet weather, you can *feel* the field!  The
lowest wire is at least 10m above ground level.  There is a house *almost* underneath the wires - I wouldn't
live there if you paid me!  I'd take a picture of it, but I can't find my camera... absent-mindedness seems to
increase with time even without HV effects  :-(

Cheers,


Howard Winter
St.Albans, England


2005\06\27@102637 by Dave VanHorn

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face

>
>Absence of research showing that something is dangerous doesn't make it safe!

In the case you quoted though, it wasn't a case of lots of real
studies being done, that found only minuscule and highly debatable
correlation.  It was more a case of "nobody cared enough to find out".


2005\06\27@103107 by Dave VanHorn

flavicon
face
At 09:23 AM 6/27/2005, Howard Winter wrote:
>Dave,
>
>On Sat, 25 Jun 2005 22:49:54 -0500, Dave VanHorn wrote:
>
> >
> > I was thinking on this lensing effect a bit.
> >
> > With an AC line, the magnetic field spends half it's time in each
> > state, so in the end, everything should average back to what it was
> > before, right?
>
>Wrong!  Does a lightbulb running on AC produce no light on average?

Has nothing to do with it. It creates heat and light with current in
either direction.
But, the magnetic field, averages to zero over time, so the net
effect over hours-years timescales should be essentally zero.


>The ones we're discussing are certainly 3-phase - and I don't know
>what you call a short distance, but walking
>under a 133kV line that crosses the road about a mile from here in
>wet weather, you can *feel* the field!

Again, it's an AC field, so while I'm certain that there is a
steering effect, it's "away" half the time, and "twoard" half the
time, so the net is zero.

Russel made a nice comparison between those tiny fields, and the ones
in your cells that if manifested on the large scale, would be quite terrifying.

2005\06\27@103901 by Russell McMahon

face
flavicon
face
>> [that noone has said:] "Wow! 1.7 times. That's statistically
>> huge!..."
>
> I don't know enough about statistics to evaluate the results of the
> study.
> Out of 29081 children with cancer, there were 64 cases of leukemia
> from
> people who lived less than 200m from (mostly) 275 and 400kV overhead
> lines
> WHEN THEY WERE BORN, compared to only 39 in control cases.  Their
> table
> certainly looks interesting, especially since things even out so
> nicely
> for larger distances and other diseases, but 100 cases is still a
> very
> small number to be doing statistics on.  And that "when they were
> born"
> thing really bugs me too, since at least in the US it is very common
> to move shortly after the birth of your first child...

All good comment. Thanks.
I agree that the 'when they were born" is an unsatisfactory measure
but

1.    If anything it would reasonably be expected to skew the results
on the low side IF the effects (if there are effects) occur
cumulatively during childhood.

2.    IF the effects (if there are ...) are primarily acting during
foetal development (as many nasty things have a habit of doing) then
"when they were born: is probably a half resaonable measure. It does
however raise even larger questions about mechanism as it points to a
possinle mother affecting influence. This points (to my mind anyway)
more strongly to a second order effect (aforesaid
traffic/sprays/pollution/socio economic/dead fish / ... ).

The thought that has now lodged in the back of my brain for ongoing
inspection and consideration is "*IF* there is a genuine 1.7 or so
multiplier over a sample of 29,000 (or 10,000) children and if, as is
presumably the case, many are less affected or unaffected or further
away from the lines or ..., then what is the true multiplier for those
properly exposed to whatever it is. There *appears* to be a major
carcinogen at work here which is being buried in the necessary
imprecision.

I posted this initially because it seemed to me to be really important
and something that should be brought to people's attention. Some few
saw it as a troll but that was not the aim. That it would be
contentious I did forsee.

I'd be interested in seeing results for a far higher sample size for
"within 50 metres" and "wires
pass over house" - as they do for many houses in the line of flight of
major pylon lines. Also - "lived in same house for xxx years
before/after birth" would be interesting. Also (even harder) "moved
out at time of birth" etc.

An interesting factoid is that there is a peak in the probability
curve AWAY from the line. It almost looks like it is a decaying
multinoded distribution, The first peak is NOT in close but out in the
100 - 200 metre range !!!. That would add some weight to the "power
line field concentrates xxx" ideas. This could be cosmic radiation (as
already suggested), ion precipitates, pollution etc. Who knows?
9Nobody yet).



       RM




       RM

2005\06\27@104722 by Dave VanHorn

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face

>
>An interesting factoid is that there is a peak in the probability
>curve AWAY from the line. It almost looks like it is a decaying
>multinoded distribution, The first peak is NOT in close but out in the
>100 - 200 metre range !!!. That would add some weight to the "power
>line field concentrates xxx" ideas. This could be cosmic radiation (as
>already suggested), ion precipitates, pollution etc. Who knows?
>9Nobody yet).

It would be amusing if the net effect of the powerline was as a
shield to the homes directly or nearly so, underneath it.

One thing I think we can take from these studies: We have many more
significant problems in life, and we should direct our attention to
whatever represents the largest real risk.

2005\06\27@105150 by John Colonias

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face
I thought I would throw my 2 cents in this discussion. In my younger
age, I was a research scientist at the Lawrence Berkeley Laboratory and
I did considerable research in the effects of EMFs in humans. Of
particular interest was the observed cases of melanoma at the Lawrence
Livermore Laboratory and we thought that it would be appropriate to
research the possibility that EMFs produced those incidences.

To make the story short, the studies we performed (I would gladly
provide to interested readers references to these papers) indicated that
there was NOT any correlation between EMFs and humans. I should
mentioned that we looked mostly at the 1 Tesla area since the
accelerators that existed in the national laboratories that we
researched operated at the vicinity of 1 T fields.

Personally, I believe that the absence of EMF is more detrimental to
humans since we have evolved in a plethora of EMF exposures including
cosmic rays.

John

{Original Message removed}

2005\06\27@111500 by Russell McMahon

face
flavicon
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> Again, it's an AC field, so while I'm certain that there is a
> steering effect, it's "away" half the time, and "twoard" half the
> time, so the net is zero.

For one phase, yes maybe.
For 3 phases, no probably.
I haven't modelled this but I suspect there's a net rotating sweeping
effect that's non circular (a la electric motor)

Consider one wire - current rises and falls. A circular magnetic field
rises and falls with it. Magnitude at a point rises and falls. If you
stand nearby you see a magnetic vector from the direction of the
conductor.

Now look at a second phase. In isolation it does the same thing. As
does the third phase. But the magnitudes and directions are different
due to their different distances and angles to you.

BUT they are 120 degrees apart in time. As one is at zero another is
ahead and another behind. The vector sum of the magnetic fields varies
not only in magnitude but ALSO in direction. If you stand (hover)
between all 3 wires highish in the air you probably get a true
rotating field. If you stand on the ground between the lines you
probably get a field that agitates to and fro a la washing machine
rotor or windscreen wipers. If you stand off to one side you get some
oscillation and with distance it turns back to an on off pulsing.

relatively close to the line on one side you get a rotating ish vector
that sweeps upwards ALWAYS. On the other side of the line you get a
vector that sweeps downwards always. Suitably affectable particles
should be suitably affected.

I think that you could make a "motor" that was balanced and suitable
weighted such that it would spin at 50 Hz ed in relatively close
proximity to the lines. That would arouse some interest I think ;-)

If my asymmetric sided sweeping concept is correct there may be a good
and bad side of the lines to live on.
Hmm - brain may be fading badly there. Need to think of effect of
reversal on vector sum. Initially it seemed that rotating vector made
sense. Bed time. Maybe dreaming will assist  visualisation - power
lines or benzene rings :-) - don't know which is worse.




       RM



2005\06\27@123811 by Gerhard Fiedler

picon face
Dave VanHorn wrote:

> Has nothing to do with it. It creates heat and light with current in
> either direction.
> But, the magnetic field, averages to zero over time, so the net
> effect over hours-years timescales should be essentally zero.

If we are talking about a lens effect... I don't think /I/ necessarily want
to be the averaging agent -- and may not you either :)

Think of light, like the light bulb over your desk. You probably can look
at it without sustaining damage. Now think of a highly concentrating lens
rotating around it that leaves the /average/ light intensity at every spot
the same: a short interval with high intensity, the rest with lower. It is
conceivable that you might feel less comfortable looking at it now, that
you even might get your eyes damaged. (The light intensity of a cutting
laser averaged over the whole body is not that much... I wouldn't want to
be in the beam, though :)

There are obviously situations where such an effect is damaging. Average is
not always a good measure for effect (damaging or otherwise).

Gerhard

2005\06\27@123900 by Ken Walker

flavicon
face
I myself blame it all on satellites.

My Reasons why

If you are unfortunate enough to be treated for cancer and then have
radiation treatment, they tattoo small crosses onto the surface of your
skin, so that the equipment can map the body surface and  try as best as
possible not to overlap the exposures. If there is an overlap you will get
double the dosage and some nasty tissue damage :o(

Satellites are allowed to pump out the maximum amount allowed so as not to
harm us little mortals here on the surface.

That's fine for a single satellite, but there are hundreds of the buggers up
there, all pointing at us and all running at the maximum power allowed, all
27/7. And they all have overlapping footprints.

So perhaps if your standing in an area where two footprints are overlapping,
your gonna get double the radiation, where three are overlapping your gonna
get three time the radiation, and there are hundreds of them up there.

As we have all seen here in the UK, Sky dishes are pretty small, which means
the radiation per square meter must be higher than that needed for a larger
dish and a weaker transmitter.

I blame it all on the satellites, those little things ( well several tones
in weight per unit ) up there in the sky where not many people look.

Just my thoughts.

:o(

{Original Message removed}

2005\06\27@124759 by Gerhard Fiedler

picon face
Dave VanHorn wrote:

>> Absence of research showing that something is dangerous doesn't make it
>> safe!
>
> In the case you quoted though, it wasn't a case of lots of real
> studies being done, that found only minuscule and highly debatable
> correlation.  It was more a case of "nobody cared enough to find out".

If you're talking about cell phones, think about who's paying for the
studies (and maybe the results). With that much money involved, I think
claiming "independence of research" in ingenuous.

Gerhard

2005\06\27@153707 by John Ferrell

face picon face
How about backing up to the foundation here a minute. Being too lazy to
search the subject I will rely on memory here. In an earlier life I worked
on a project that measured the density of high pressure steam in a lab
device. We used a Cesium source (registered with AEC & all that) as an
emitter. It put out Alpha, Beta and Gamma radiation. As I recall, the Alpha
was blocked by aluminum foil, the Beta ray was bent to our target shield
(Big Magnet!) and the Gamma charged into a lead pile to be absorbed. Rather
than try to shield the lab from Cosmic radiation, we just subtracted the
background count. I thought that Cosmic was essentially Gamma radiation and
therefore about all you could do with it is shield and not too easy to do
that!

Now you guys are talking about focusing Cosmic radiation like it is common
place.
I am not convinced it can be done at all, let alone with power distribution
lines. How about some evidence.

John Ferrell
http://DixieNC.US

{Original Message removed}

2005\06\27@174758 by Peter
picon face


On Sun, 26 Jun 2005, Jim Korman wrote:

> Lindy Mayfield wrote:
>> My mobile stays charging on my desk where I have speakers and usually
>> listen to online radio.
>> Every few hours seemingly at random, or before I get a call, I can hear
>> quite well a recurring pattern and rhythm:
>> Da-da dot da-da dot da-da dot da-da dot

If it helps any my speakers are the same. It's cheap amplifiers
connected to undecoupled long wires.

>> The tone is around 200 Hertz (somewhere about a D above middle C).
>> It seems this little thing puts out a lot of power to affect the speakers
>> like this.  I'm not saying it is scrambling my brain or making me yell at
>> the cat, but I do wonder what is going on there.

Yell at the cat, see if it helps ;-)

Anyway you could get rid of the noise by using ferrite cores on all the
cables in and out of the powered speakers (I assume that's what you
have).

Peter

2005\06\27@184827 by Peter

picon face

On Tue, 28 Jun 2005, Russell McMahon wrote:

> It would be greatly appreciated (and not just by me) that any comments on
> this thread involving tinfoil hats, black helicopters and their ilk get
> posted to OT rather than EE.

Imho both black helicopters and tinfoil hats are on topic for EE. The
remainder of the thread may not be ;-)

Peter

2005\06\27@185300 by Peter

picon face

On Mon, 27 Jun 2005, Dave VanHorn wrote:

> You live in a field that's far larger, at about 25-50uT, and you fearlessly
> walk around changing the polarity willy nilly, with total disregard for the
> consequences.

The magnetic field is likely the part that does not play a role. Most
people do not consider the other factors: high voltage corona breaks
down some 'natural' chemical pollutants and haves them floating in the
area practically continuously. It also generates NOx which is very bad,
plus ozone, which is a proven carcinogen.

Wrt em field or chemical factors, it would be interesting to know
whether any health problems are associated with work near high voltage
dc sources (or relatively low current).

Peter

2005\06\27@192159 by Russell McMahon

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face
>>> Every few hours seemingly at random, or before I get a call, I can
>>> hear quite well a recurring pattern and rhythm: Da-da dot da-da
>>> dot da-da dot da-da dot

> If it helps any my speakers are the same. It's cheap amplifiers
> connected to undecoupled long wires.

Partially. But mainly it's an engineering foul up in GSM that wasn't
properly noticed until too far into the process to allow it to be
fixed. The energy is large and system that YOU made trying to get
approval for something that did this would be thrown out immediately.
In this case large might made right as to rectify it was essentially
impossible without starting again from scratch.


           RM

2005\06\27@200445 by Peter

picon face

On Tue, 28 Jun 2005, Russell McMahon wrote:

>> Again, it's an AC field, so while I'm certain that there is a steering
>> effect, it's "away" half the time, and "twoard" half the time, so the net
>> is zero.
>
> For one phase, yes maybe.
> For 3 phases, no probably.
> I haven't modelled this but I suspect there's a net rotating sweeping effect
> that's non circular (a la electric motor)

The net sweeping effect is very sinusoidal anywhere outside the
perimeter enclosed by the wires, and has no turning moment for a point.
A small person or object can be considered a point for distances > 10
units from the centroid of the lines. The turning moment will be smller
than 1% of the field by then. This applies for both the electric and for
the magnetic component.

If you have access to gnuplot you can observe it easily. The following
statement:

plot [t=0:4*pi] [-1.5:3.5] sin(t), sin(t+2*pi/3), sin(t+4*pi/3), \
       sin(t)+sin(t+2*pi/3)+1/3*sin(t+4*pi/3)+2.25

plots the E field on the fourth corner of a rhombus formed by 3 3-phase
power lines and a point probe (M) intersecting a plane at right angles,
where the power lines form an isosceles triangle on the plane:

   S
R     M
   T

Since this measuring point is at 1.1547005 units (2/sqrt(3)) from the
axis between the phases, and the field obeys an inverse square law you
can easily calculate the field at some distance. F.ex. for a 133kV
field, assuming inverse square law (it isn't, it is distorted by the
ground plane and by the corona) to equal a 240V field it takes a
distance ratio of >23:1. At 10 meters from the hv voltage the field from
a wire attached to a small portable generator powering your lamp and
tools (at 0.5 meters from you) will be stronger than the one from the
133kV line. But the corona and the buzz from the 'electrostatic speaker'
formed by the charged air is going to make you numb even if the smell of
NOx and O3 will not make you sick before that.

As to magnetic fields, remember ampere-turns (B~N*I). I have never seen
a hv line that makes a compass even twitch (even a digital compass that
can respond fast), but the stray field from a wall wart at one meter
from you is probably much stronger than the field from the hv line.

I think that the chemical connection is more promising. NOx and O3 are
both denser than air and will descend under the lines in still air (fog,
smog etc), they being produced continuously. They will also react with
pollutants to form even more noxious compounds. It would be interesting
to know if the places with the sick kids were *downwind* from the lines
for those periods when winds would be weak in the area (a strong wind
would likely spread out the gases). Looking up the exposure limits to
NOx and O3 could also be instructive.

Peter

ps: any errors in this posting may be justified - it's 3AM.

2005\06\28@024547 by Lindy Mayfield

flavicon
face
They are powered speakers.  But I've sort gotten used to the sound because often it warns of an incoming call before the phone rings.  That way I can have a Pavlovian response and start to sweat thinking it is someone calling for support or the boss calling to yell at me.  That's when the cat gets it.

"Bad kitty!"

{Original Message removed}

2005\06\28@032100 by Luis.Moreira

picon face
Hi blame it all on my parents...
They should have better genetic material...
But they are just two Portuguese short arses.
                                                               Luis

Luis Moreira
@spam@luis.moreiraKILLspamspamjet.uk
tel. 01235464615
JET PSU Department
UKAEA Culham Division
J20/1/55, Culham Science Centre
Abingdon
Oxfordshire
OX14 3DB


{Original Message removed}

2005\06\28@110206 by Dave VanHorn

flavicon
face
At 01:44 AM 6/28/2005, Lindy Mayfield wrote:
>They are powered speakers.  But I've sort gotten used to the sound
>because often it warns of an incoming call before the phone
>rings.  That way I can have a Pavlovian response and start to sweat
>thinking it is someone calling for support or the boss calling to
>yell at me.  That's when the cat gets it.

This is called "Direct rectification".

Most any device that has a diode in it will have this to some degree.
The phone emits short, but relatively powerful bursts of RF to
communicate, and those get rectified to a few 10's of mV of DC, which
then get amplified by whatever they are connected to.


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