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Of flying frogs and levitrons
Michael V Berry,Andre K. Geim +1 more
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In this article, it was shown that stable zones always exist on the axis of a field with rotational symmetry, and include the inflection point of the magnitude of the field.Abstract:
Diamagnetic objects are repelled by magnetic fields. If the fields are strong enough, this repulsion can balance gravity, and objects levitated in this way can be held in stable equilibrium, apparently violating Earnshaw's theorem. In fact Earnshaw's theorem does not apply to induced magnetism, and it is possible for the total energy (gravitational+magnetic) to possess a minimum. General stability conditions are derived, and it is shown that stable zones always exist on the axis of a field with rotational symmetry, and include the inflection point of the magnitude of the field. For the field inside a solenoid, the zone is calculated in detail; if the solenoid is long, the zone is centred on the top end, and its vertical extent is about half the radius of the solenoid. The theory explains recent experiments by Geimet al, in which a variety of objects (one of which was a living frog) was levitated in a field of about 16 T. Similar ideas explain the stability of a spinning magnet (Levitron TM ) above a magnetized base plate. Stable levitationread more
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Biomedical Applications of Untethered Mobile Milli/Microrobots
Metin Sitti,Metin Sitti,Hakan Ceylan,Wenqi Hu,Joshua Giltinan,Mehmet Turan,Sehyuk Yim,Eric Diller +7 more
TL;DR: A comprehensive review of the current advances in biomedical untethered mobile milli/microrobots and discusses the existing challenges and emerging concepts associated with designing such a miniaturized robot for operation inside a biological environment for biomedical applications.
Journal ArticleDOI
Safety of Strong, Static Magnetic Fields
TL;DR: There is no replicated scientific study showing a health hazard associated with magnetic field exposure and no evidence for hazards associated with cumulative exposure to these fields, and the very high degree of patient safety in strong magnetic fields is attributed to the small value of the magnetic susceptibility of human tissues.
Journal ArticleDOI
Ground-based facilities for simulation of microgravity: organism-specific recommendations for their use, and recommended terminology.
Raúl Herranz,Ralf Anken,Ralf Anken,Johannes Boonstra,Markus Braun,Peter C. M. Christianen,Maarten C. De Geest,Jens Hauslage,Reinhard Hilbig,Richard Hill,Michael Lebert,F. Javier Medina,Nicole Vagt,Oliver Ullrich,Jack J. W. A. van Loon,Ruth Hemmersbach +15 more
TL;DR: The range of applicability of the various ground-based microgravity simulators for biological specimens was carefully evaluated by using organisms that have been studied extensively under the conditions of real microgravity in space.
Journal ArticleDOI
Diamagnetic levitation: Flying frogs and floating magnets (invited)
M. D. Simon,A. K. Geim +1 more
TL;DR: In this paper, it was shown that non-magnetic substances can be levitated in a magnetic field and can stabilize free levitation of a permanent magnet and that the introduction of diamagnetic material at special locations can stabilize such levitation.
Journal ArticleDOI
Magnetoreception in plants
Paul Galland,Alexander Pazur +1 more
TL;DR: Two further mechanisms for magnetoreception are currently receiving major attention: the “radical-pair mechanism” consisting of the modulation of singlet–triplet interconversion rates of a radical pair by weak magnetic fields, and the ”ion cyclotron resonance” mechanism.
References
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Book
Electrodynamics of continuous media
TL;DR: In this article, the propagation of electromagnetic waves and X-ray diffraction of X rays in crystals are discussed. But they do not consider the effects of superconductivity on superconducting conductors.
Tables of physical and chemical constants
G. W. C. Kaye,T. H. Laby +1 more
TL;DR: In this paper, the authors present a survey of the properties of inorganic compounds and their properties in general physics, including properties of solutions, properties of chemical bonds, and properties of nuclei.
Journal ArticleDOI
Levitation in Physics
TL;DR: Levitation is used for containerless processing and investigation of materials, for frictionless bearings and high-speed ground transportation, for spectroscopy of single atoms and microparticles, and for demonstrating superconductivity in the new oxide superconductors.