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Exact time-independent spherically symmetric black hole solutions of the (4+3)-dimensional Kaluza–Klein theory are obtained by imposing the isometry group E2 on the unified metric. The solutions include the five-dimensional Dobiasch–Maison–Lee solutions as a special case. The physical implication of the solutions is discussed. [ABSTRACT FROM AUTHOR]

A unified theory based on a homogeneous fiber bundle Q(M,G/H) is discussed in detail. In spite of the fact that the theory retains the full G-gauge invariance, the physical gauge group K is shown to be K=H*/(H∩H*), where H* is the centralizer of H in G. A principal fiber bundle P(M,G,H) is also constructed by introducing an additional left action H on P(M,G) that commutes with the right action G, and a unified theory based on P(M,G,H) is discussed. It is shown that the theory based on Q(M,G/H) is, in fact, the H projection of the Einstein–Hilbert action from P(M,G,H), with the identification Q(M,G/H)=P(M,G,H)/H. [ABSTRACT FROM AUTHOR]

The effect of field emission cycles on printed carbon nanotubes was investigated using scanning electron microscopy and current-voltage measurement. After multiple emission cycles, the printed nanotubes irreversibly deformed to orient themselves parallel to the field direction and, from them, remarkably enhanced emission image with good uniformity was demonstrated. Corresponding gradual decrease in the field emission threshold and increase of field enhancement factor (β) were also observed during field emission cycles. [ABSTRACT FROM AUTHOR]