Volume 46, Issue 5

Lorentz transformations of two macroscopic devices are discussed. In each case, the overall momentum flux into every static element of matter vanishes. It is shown that a Lorentz transformation of the energy-momentum 4-vector of each system agrees with special relativity. In particular, using the ordinary definition of 4-momentum of electromagnetic fields, it is proved by means of a particular form of Poincare's stress tensor, that there is no 4/3 factor in the transformation of the entire momentum of a uniformly charged spherical shell

Analysis is carried out for an alternating arrangement of laminae which have either uniaxial permittivity or uniaxial permeability dyadics. The unit cell is constructed of two laminae such that the ones with the uniaxial permittivity dyadic alternate with the ones with the uniaxial permeability dyadic through the stack. It is assumed that both dyadics have the same optic axis. The 4-vector method is utilized to construct a characteristic matrix for the two-lamina unit cell. After assuming that each lamina is electrically thin, the properties of an equivalent medium are obtained: both the permeability and the permittivity dyadics of the equivalent medium are biaxial

Quantum fields can be characterized by state functionals and corresponding functional equations. Within this functional representation exchange forces of composite particles are discussed for the case of composite bosons which are bound states of two constituent fermions. The dynamics of these bosons is formulated by means of a weak mapping theorem which establishes a map between the functional equations for the composite boson quantum field and the constituent original fermion quantum field. Evaluation of this theorem leads to expressions which can be identified as quantum field theoretic "direct" forces and exchange forces for or between composite particles. By some theorems the exchange forces are evaluated and an estimate for them is given. The expressions for the direct forces correspond to those which were already derived in previous papers to discuss composite particle dynamics.

With a whole-body NMR imager working at 1.5 T localized 1 H and 31 P spectra were obtained using the CODEX sequence. Examples are presented: With ethanol 'H spectra the resolution, stability, and sensitivity are documented. Human in vivo investigations of the yellow bone marrow of (13 mm) 3 volume elements show well resolved spectra with a good signal-to-noise ratio. An example for 31 P spectroscopy is also given

The partial electronic conductivity of Ag +- ß"-alumina was determined in the temperature range 180-200 °C, using Wagner's asymmetric galvanic polarization cell Ag| Ag + -ß"-alumina | Pt. The electron conductivity is 4.5 x 10 - 8 Ω -1 cm -1 , while the hole conductivity is about seven orders of magnitude lower at the silver activity a Ag =1at 200 °C. These results are compared with earlier data on ß/ß"-alumina. The conduction mechanism and the effect of the electronic conductivity on the application of Ag + -ß"-alumina are discussed

The specific heat of liquid metals is calculated using a fluid of Percus-Yevick plus tail as a reference system together with the Cumming potential in a random-phase approximation. It is shown that the improved semi-empirical hard sphere direct correlation function proposed by Colot et al. leads to a drastic improvement of C p values over the HS model

By assuming the validity of the principle of inertia and the existence of a privileged frame, the transformation laws (TL) between inertial frames are investigated in ether theories. For onedimensional space the TL's are fixed up to two undetermined functions of absolute velocity, Δ (v) and E(v). If the principle of relativity is finally assumed, these functions acquire their well known Lorentzian expressions Δ L and E L. It is concluded that special relativity theory is "unstable", in the sense that any shift, however small, of Δ away from Δ L and/or of E away from E L leads to an ether theory. In Earth-based experiments one can expect deviations from c of the two-way and one-way velocity of light of the order of 10 -12 and 10 -9 respectively

Various refined potentials describing the intra- and inter-molecular force fields of water molecules arc used to calculate the properties of the gas-phase water dimer. The intra-molecular parts have been taken from spectroscopic or quantum-chemical sources. The minimum energy structure was found iteratively using the first derivatives of the potential; the force-constant matrix was constructed by numerical difierentation. A quite close agreement between the Bopp-Jancso-Heinzinger and the Matsuoka-Clementi-Yoshimine-Lie potentials is found. The treatment is applied to seven observed water-dimer isotopomeric isomerizations

The thermodynamic and structural properties of water along two supercritical isotherms at 673 and 773 K in the pressure range from 0.3 to 30 kbar have been studied by the NPT-ensemble Monte Carlo method using a TIP4P intermolecular pair potential. Simulated values of the configurational enthalpy, molar volume, isobaric heat capacity, isothermal compressibility, and thermal expansion coefficient are found to be in a rather good agreement with experimental data, although the critical point of the TIP4P water model is supposed to lie about 50 degrees lower than observed experimentally. The analysis of simulated atom-atom radial distribution functions as well as the dimerization energy distributions clearly shows that hydrogen bonding persists under the conditions studied, despite the fact that the water structure may be considered as "argon-like" in terms of oxygen-oxygen distribution functions (i.e. close to that of a simple liquid)

We present a microwave Fourier transform spectrometer in the region of 18 to 26.4 GHz with an increase in sensitivity roughly by a factor of ten in comparison to a former set up. Measurements of rotational transitions of isotopomers of carbonylsulfide, OCS, in natural abundance and of rovibrational transitions of methane, CH 4 , illustrate the improvement

The rotational spectrum of cis-2-butene has been measured in the range from 5 to 40 GHz with microwave Fourier transform spectroscopy to determine internal rotation and centrifugal distortion parameters

The vacuum-UV-photoelectron spectra of Se 2 , Se 5 , Se 6 , Se 7 , and Se 8 have been recorded at a photon energy of h ν= 10.0 eV. The isolated molecules are examined in a supersonic molecular beam employing a new photoelectron-photoion coincidence technique. The structure of the photoelectron spectra of selenium molecules with even and odd numbers of atoms differs in a characteristic manner. While the spectra of Se 6 and Se 8 show one single broad band, three separated bands with different intensities are observed for Se 5 and two for Se 7 . The spectra are compared to molecular orbital energy calculations based on theoretically supposed geometries. The comparison indicates that Se6 and Se8 have Dnd-symmetrical ring structures, whereas Se 5 and Se 7 are C 1h -symmetrical rings

This paper describes a method to solve the spectral equation for the balance of turbulent kinetic energy in a stably stratified turbulent shear flow. The cospectra of vertical momentum and heat flux arc modelled with the aid of a basic eddy-viscosity (or turbulent exchange coefficient) function. For the term representing the inertial transfer of turbulent kinetic energy, Pao's [Phys. Fluids 8 (1965)] form is assumed. Analytical expressions for the three-dimensional kinetic energy spectrum as well as the cospectra of momentum and heat flux are obtained over the range of wave numbers k≥kb, which includes the inertial subrange kb≪k≪ks and the viscous subrange k>ks (k b and k s are the buoyancy and Kolmogorov wavenumbers, respectively). The two one-dimensional spectra, e.g., the kinetic energy spectra of the horizontal and vertical components of turbulence are derived from the three-dimensional kinetic energy spectrum. These one-dimensional spectra are compared with the measured data of Gargett et al. [J. Fluid Mech. 144 (1984)] for the case I ( = k s /k b ) = 630. Finally, we compute the basic eddy-viscosity function and discuss its behavio