منابع مشابه
Magnetic Fields and Rotations of Protostars
The evolution of the magnetic field and angular momentum in the collapsing cloud core is studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculate the cloud evolution from the molecular cloud core (nc ≃ 10 4 cm, r = 4.6× 10 AU) to the stellar core (nc ≃ 10 22 cm, r ∼ 1R⊙), where nc and ...
متن کاملOptimal rotations of deformable bodies and orbits in magnetic fields.
Deformations can induce rotation with zero angular momentum where dissipation is a natural "cost function." This gives rise to an optimization problem of finding the most effective rotation with zero angular momentum. For certain plastic and viscous media in two dimensions the optimal path is the orbit of a charged particle on a surface of constant negative curvature with a magnetic field whose...
متن کاملElectric-Magnetic Duality Rotations and Invariance of Actions
For D=4 theories of a single U(1) gauge field strength coupled to gravity and matters, we show that the electric-magnetic duality can be formulated as an invariance of the actions. The symmetry is associated with duality rotation acting directly on the gauge field. The rotation is constructed in flat space, and an extension to curved spaces is also given. It is non-local and non-covariant, yet ...
متن کاملMagnetic color symmetry of lattice rotations in a diamagnetic material.
Oxygen octahedral rotations are the most common phase transitions in perovskite crystal structures. Here we show that the color symmetry of such pure elastic distortions is isomorphic to magnetic point groups, which allows their probing through distinguishing polar versus magnetic symmetry. We demonstrate this isomorphism using nonlinear optical probing of the octahedral rotational transition i...
متن کاملElectric-magnetic Duality Rotations in Non-linear Electrodynamics
We show that there is a function of one variable’s worth of Lagrangians for a single Maxwell field coupled to gravity whose equations of motion admit electric-magnetic duality. Such Lagrangians are given by solutions of the Hamilton-Jacobi equation for timelike geodesics in Witten’s two-dimensional black hole. Among them are the Born-Infeld Lagrangian which arises in open string theory. We inve...
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ژورنال
عنوان ژورنال: Lab Animal
سال: 2019
ISSN: 0093-7355,1548-4475
DOI: 10.1038/s41684-018-0235-0