XPost: sci.electronics.design   
   From: bill.sloman@ieee.org   
      
   On 20/02/2026 3:54 am, john larkin wrote:   
   > On Thu, 19 Feb 2026 14:13:06 +0100, nospam@de-ster.demon.nl (J. J.   
   > Lodder) wrote:   
   >   
   >> Bill Sloman  wrote:   
   >>   
   >>> On 19/02/2026 9:56 pm, J. J. Lodder wrote:   
   >>>> Bill Sloman  wrote:   
   >>>>   
   >>>>> On 19/02/2026 7:49 am, Ross Finlayson wrote:   
   >>>>>> On 02/18/2026 12:43 PM, Python wrote:   
   >>>>>>> Le 18/02/2026 à 20:13, Ross Finlayson a écrit :   
   >>>>>>> ..   
   >>>>>>>> and, you know, magnetic monopoles, is widely employed   
   >>>>>>>> in medical imaging and the like.   
   >>>>>>>   
   >>>>>>> No.   
   >>>>>>   
   >>>>>> Resonance imaging (NMR) is a thoroughly different mechanism   
   >>>>>> than Roentgen rays.   
   >>>>>   
   >>>>> But as the name implies, it's nuclei of the atoms involved that exhibit   
   >>>>> the resonance. It's a remarkably low energy effect, and you need   
   >>>>> remarkably high magnetic fields to get it to give you a detectable   
   signal.   
   >>>>   
   >>>> Nevertheless, it is easily demonstrated in the kitchen   
   >>>> with some simple electronics.   
   >>>   
   >>> Sort of.   
   >>>   
   >>> https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance   
   >>>   
   >>> There are lots of different ways to exploit nuclear magnetic resonance.   
   >>> The earth's magnetic field is high enough to let you devise experiments   
   >>> that can demonstrate the effect on a kitchen table.   
   >>   
   >> Nothing 'sort of'.   
   >> You -can- easily demonstrate the effect on the kitchen table.   
   >> (at audio frequencies)  Wikipedia is right here.   
   >>   
   >> Jan   
   >   
   > NMR was a fairly popular analytical chemistry business for a while. We   
   > made pulsed-field gradient coil drivers and temperature controllers   
   > for Varian.   
   >   
   > But superconductive magnets and liquid helium are expensive, and other   
   > techniques took over. It was common to visit a lab that had a giant   
   > magnet in the corner, warm and collecting dust. A similar mass spec   
   > technique, FTMS,  died for the same reason... too expensive.   
   >   
   > Agilent bought Varian to get their medical stuff but immediately   
   > killed the NMR operation. I think Bruker still does NMR.   
   >   
   > Hospitals prefer cat scans to MRIs these days. Cat scans are much   
   > cheaper.   
      
   But not as good. When I had a ruptured intervertebral disk back in 1988,   
   I paid extra to get an MRI scan and my clinician was blown away by the   
   higher resolution it offered - it was about twice as good as he saw in   
   X-ray based CAT scans. He got my okay to use it for teaching purposes.   
      
   And it didn't raise my risk of getting cancer at all.   
      
   --   
   Bill Sloman, Sydney   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)