[en] By studying the purely gravitational sector of a higher-dimensional matter-gravity coupled theory, one can see that in the case of nonvanishing torsion the effective 4-dimensional theory exhibits two gauge potentials that transform under the action of a single gauge group

[en] In this work a frame-indipendent approach to the notion of convected derivation is developed, and a systematic classification of these derivatives in terms of an absolute vorticity and deformation rate in classical space-time is given. In the case of derivatives following a motion it is distinguished between intrinsic and exstrinsic convected derivatives. A link is estabilished between the class of convected derivatives and the class of affine connections on classical space-time compatible with its metric structure

[en] A nonlinear electrodynamics in space-times with torsion is proposed. It is shown that in the Riemann-flat space with torsion it is possible to place a limit on the torsion vector based on the upper bound for the mass of the photon

[en] The Euclidean Einstein equation is solved with a cosmological constant and an extra quantum term arising from the insertion of a minimum resolution distance in the background theory, taking the metric to be of the Robertson-Walker type. In the case λ = 0 a solution is obtained which represents a new kind of wormhole space-time. The case λ > 0 admits a similar interpretation as for the solutions obtained by Myers using a third-rank tensor field or those derived by Halliwell and Laflamme using a conformal scalar field

[en] Dealing with a quantum open system in terms of a (linearly) modified Liouville-von Neumann equation, the question is asked whether such an equation may in general account for a transition from a pure state to a thermal mixture. It is found that no contradiction arises requiring that the modification satisfies the general conditions imposed by the identification of the final density matrix with that of a thermal mixture. The reasons for the impossibility of describing the inverse transition in the same formalism are also analysed

[en] The damping effects of devices such as an rf-coil and Ge or Bi crystals on the interference fringes in the interference-type experiments are analysed. They are investigated in terms of the interaction between the device and the wave packets. The fluctuations deriving from the macroscopic characteristics of devices are also considered, and the damping effects are analysed. The visibility of the interference fringes are calculated and compared with the results of the neutron interference experiment. Reliable results are obtained which indicate the tendency of the results measured by the Missouri-Columbia group and it is certai11n that our method is more suitable in order to investigate experiments such as those which make use of wave packets. The intensity of the wave packet is also discussed. The difference between the intensity of a beam made up of several single plane waves and the intensity of a real wave packet such as the one describing pulsed neutrons is pointed out

[en] A semi-classical synthesis of classical mechanics, wave mechanics, and special relativity yields a unique nonlinear energy-wave structure of relations (velocity triad uv = c²) fundamental to modern physics. Through the above vehicle, using Maxwell's equations, charge quantization and the fine structure constant are derived. It is shown that the numerical value of the nonlinear charge-field self-interaction range for the electron is of the order of 10^-13 m, which is greater than the classical electron radius but less than the Compton wavelength of the electron. Finally, it is suggested that the structure of the electron-in-space is expressed by a self-extending nonlinear ''fractal geometry'' based on derived numerical values obtained from our model, thus opening this presentation of charge-field structure to experimental testing for possible verification

[en] In 1927 Brillouin, supposing all elementary particles to be distinguishable, gave a unified approach to the three familiar statistics for particles. In order to this, he assumed that each level has a capacity, each particle has a volume, and each particle in a level modifies its capacity. In this paper it is shown that it is possible to give a strictly probability reformulation of Brillouin's unified theory

[en] Unsteady mass transfer from a vertical plate in a transverse magnetic field is investigated assuming that all the fluid properties are constant. The solution is dependent on two parameters, namely the Prandtl number, Pr, and the Schmidt number, Sc. An analytical solution is presented which is valid at small values of time and this solution is extended to large values of time by using a modified Crank-Nicolson scheme

[en] Starting with a classical theory with conformal coupling, it is defined a ''gravitational potential'' which can undergo spontaneous symmetry breaking. The action integral of the corresponding quantum theory is derived from a consistently defined effective potential by using a correspondence simple method that preserves the equivalence principle. Two particular cases of the general theory are considered and discussed