Date: Wed, 25 May 2011 16:53:01

Author: --- Urs Lauterburg

Subject: Re: Biophysics Demos?/Ballistocardiogram

Post:

Jerry,

Could you provide the title of this paper. I can login to
sciencedirect by my university but I need the title to locate the
paper.

Thank you for the service.

Regards

Urs

Urs Lauterburg
Physics demonstrator
Physikalisches Institut
University of Bern
Switzerland


> The 1950 paper references a 1945 paper that claims to have
>correlated the minor oscillations to actual events in the body
>related to elasticity of tissue and pulsed flows of blood. The
>paper below, which used a vertical BCG and strain gauges (and
>appears to be more capable), also showed the minor oscillations. So
>they must be valid waveforms. However, the authors also point out
>that most BCGs have a natural frequency that influences the
>waveforms. But we're not doing medicine so it's probably okay.
>Quite an interesting topic -- but not for the faint of heart...
>
>
>
>
>Jerry D
>
>
>At 5/23/2011 03:01 PM, you wrote:
>>I admit that our apparatus may not be perfect, may have resonances,
>>ability to
>>store energy, etc. However, you have all prompted me to dig deeper,
>>and despite the limitations of the apparatus, it appears the basics
>>of our signal is as real as can be. Going back to Nov. 1939 I read
>>the same Isaac Starr quoted in the later Time magazine article.
>>I've posted below some figures from his paper showing a schematic
>>of the signal correlated to EKG and a few actual traces which are
>>similar to what we recorded.
>>http://web.physics.ucla.edu/demoweb/demomanual/mechanics/third_law/ballistocard.jpg
>>There is a huge range of variability shown in traces from different people,
>>including the number and height of oscillations. The article points out that
>>respiration also has a large effect on the signal and holding
>>breath can be done
>>to avoid it.
>>You can see the whole article with many traces here
>>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC434977/pdf/jcinvest00562-0001.pdf
>>
>>Martin Simon
>>
>>For those not yet bored with the subject, this is a later and more
>>interesting article, STANDARDIZATION OF BALLISTOCARDIOGRAM, Starr
>>et al, 1950. In it, the authors state "the Ballistocardiogram is
>>Related to the First Derivative of Cardiac Force and so to the
>>Third Derivative of the fluid displacement Curve". They show some
>>physical models and do experiments injecting fluids.
>>
>>http://circ.ahajournals.org/cgi/reprint/1/5/1073


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