7,027 research outputs found
Astrophysical Implications of Higher-Dimensional Gravity
We review the implications of modern higher-dimensional theories of gravity
for astrophysics and cosmology. In particular, we discuss the latest
developments of space-time-matter theory in connection with dark matter,
particle dynamics and the cosmological constant, as well as related aspects of
quantum theory. There are also more immediate tests of extra dimensions,
notably involving perturbations of the cosmic 3K microwave background and the
precession of a supercooled gyroscope in Earth orbit. We also outline some
general features of embeddings, and include pictures of the big bang as viewed
from a higher dimension.Comment: 23 pages, 2 figures; to appear in Space Science Reviews; v3: typos
corrected and minor changes to text, expanded derivation of fundamental mode
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Stability of the magnetic Schr\"odinger operator in a waveguide
The spectrum of the Schr\"odinger operator in a quantum waveguide is known to
be unstable in two and three dimensions. Any enlargement of the waveguide
produces eigenvalues beneath the continuous spectrum. Also if the waveguide is
bent eigenvalues will arise below the continuous spectrum. In this paper a
magnetic field is added into the system. The spectrum of the magnetic
Schr\"odinger operator is proved to be stable under small local deformations
and also under small bending of the waveguide. The proof includes a magnetic
Hardy-type inequality in the waveguide, which is interesting in its own
OrganiZational communication and organiSational communication: Binaries and the fragments of a field
In this paper, I employ personal narrative to help cast light on connections and tensions between organiZational communication research, as produced in the United States, and organiSational communication research, as produced in Aotearoa New Zealand. I address the issue by highlighting three sets of differences between these bodies of research: canonical, institutional and theoretical. I then unpack how these differences are apparent in my own university before sketching out three ways in which we might productively use such tensions to achieve radical engagement, and critique disciplinary others, identities, and locations
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From local to global control
In this paper the authors study the problem of the existence of multiple local operating points in control systems. In particular, they consider a method of going from local to global control, i.e. given a number of local, linearized systems, from which global system do they come, and, can global controllers be determined in this case
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