Made from gelatin, starch-based edible glitter, acacia (gum arabic) powder, Zea Mays starch and vegetable stearate, Passion Dust is not as safe as it claims, according to gynecologists. “The vagina contains a delicate balance of good bacteria, which are there to protect it,” Dr. Vanessa Mackay, spokesperson for the Royal College of Obstetricians and Gynaecologists (RCOG) tells The Independent . “If women place foreign objects inside their vagina, they risk disturbing this balance which may lead to infection, such as bacterial vaginosis or thrush, and inflammation.”
The drag force can be used to the electrodynamic system's advantage, however, as it creates a varying force in the rails that can be used as a reactionary system to drive the train, without the need for a separate reaction plate, as in most linear motor systems. Laithwaite led development of such "traverse-flux" systems at his Imperial College laboratory.  Alternatively, propulsion coils on the guideway are used to exert a force on the magnets in the train and make the train move forward. The propulsion coils that exert a force on the train are effectively a linear motor: an alternating current through the coils generates a continuously varying magnetic field that moves forward along the track. The frequency of the alternating current is synchronized to match the speed of the train. The offset between the field exerted by magnets on the train and the applied field creates a force moving the train forward.
Shinkansen routes are completely separate from conventional rail lines (except Mini-shinkansen which goes through to conventional lines). Consequently, the shinkansen is not affected by slower local or freight trains, and has the capacity to operate many high-speed trains punctually. The lines have been built without road crossings at grade . Tracks are strictly off-limits with penalties against trespassing strictly regulated by law. It uses tunnels and viaducts to go through and over obstacles rather than around them, with a minimum curve radius of 4,000 meters (2,500 meters on the oldest Tōkaidō Shinkansen).