Lecture 19 March 5,2015 Static Magnetic Fields Chapter 8

Magnetic Field Forces 1 density 2. Torque moment Χ is the magnetic susceptibility For two plates and

Biological Effects of Magnetic Fields

Biological Changes with Magnetic Fields 4. Changes in H 2 O vaporization rate 5. Decrease in skin temperature 6. Changes in O 2 concentration 7. Changes In radical pair lifetimes. 8. Change in cell culture growth at low fields.

In Vivo Studies 1. Animal Navigation, Birds, bees, salmon 2. Rat cognitive function modified by magnetic fields of 14µT horizontal 116µT vertical also 55µT and 240µT vs. normal of 14µT and 34µT 3. 5T field suppressed eating and drinking 4. Analgesia, pain reduction, by reducing the magnetic field to < 1µT. Also to fields of 79µT Foot on hot plate. Also 60hz at 299µT

In Vivo Studies 5. Changes in Heart rate at 100mT in rats. 80% of the time 6. Some effects observed in trout embryos 7. Ohkubo, Changes in micro circulation, modulated vessel size at 1mT up to 180mT for 10minutes. Reduced or expanded vessel size dependent on animal stress. Moved toward normal. Normal capillaries showed no change. 8. This is backed up by other studies.

Reproductive and Development 1. High fields MRI, at 0.7T +RF Minimal effects of sperm motility etc. for 24hour exposures up to 35 days on mice. 2. Also on fetus. 3. Some reduction in weight for long exposures of embryos to MRI fields 4. Exposures of chick embryos to 29mT for 6 days could induce irreversible effects on cell migration and differentiation. Measured at day 13.

Development Changes 1 Prolonged transportation of fertilized salmonid eggs and trout at 4mT, lower mortality rates. Effects on orientation in fields from 0.5 to 1mT 2. Effects on carp muscle at 50 to 70mT 3. Lots of other effects in this range.

Cell Changes 1. Reduction in Cell growth, ecoli, at B< 1µT 2. Changes to antibiotic resistance for several different cases. 3. Other studies show not effects at field of 0.35mT and 2.45mT for different types of cells and also O.2T,1T and 1.5T on fetal human lung fibroblast cells 4. We see changes in growth rates for fibrocarcoma cells but not fbroblast cells at 100µT

Medical Applications 1. MRI, FMRI imaging 2. Bone growth and repair 3. Transcranial Stimulations. Can get 5mm resolution with figure eight coils. τ = 0.1ms to 0.2ms B max = 1T for motor cortex 4. MEG, use squids to measure T 5. MCG