Ein Beitrag zur Theorie der inneren Feldemission

The internal field emission (Zener-tunneling) is examined from two directions, using a onedimensional model. In section I the transition probability is calculated using the Houston expansion, but without perturbation theory, as has been used in previous papers by other authors. The calculation permits an examination of the various perturbation approximations. It is found, that the validity of the first approximation depends critically upon the residue of the interband coupling function. This residue contains the Keldysh factor, which is determined here. In section II the transition probability is calculated using free electron functions, again without perturbation theory. The same transition probability is obtained in both cases.     

Über Scharen positiver Operatoren

Ohne Zusammenfassung     

An interactive system for the loading of cargo aircraft

The paper describes an interactice, computer based procedure for solving the variant of the vehicle loading problem encountered when loading containers and pallets into an aircraft. The procedure is heuristic and practical oriented; it is presently being implemented by Scandinavian Airlines.     

Copolymerisationsparameter des Systems α-Methylstyrol-Styrol

Zusammenfassung Die Parameter für die radikalische Copolymerisation von α-Methylstyrol und Styrol wurden neu bestimmt. W?hrend die UV-Spektroskopie zur Analyse der Zusammensetzung der Copolymeren ungeeignet ist, ergeben IR-Spektroskopie und Protonenresonanz gut übereinstimmende Copolymerisationsparameter.

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Summary The monomer reactivity ratios of the copolymerization of α-methylstyrene and styrene are reinvestigated. The determination of the copolymer compositions carried out by UV-spectroscopy is insufficient, whilst the infrared analysis and the protonresonance represent constants of copolymerization in good agreement.

     

Magneto‐sensitive Elastomers in a Homogeneous Magnetic Field: A Regular Rectangular Lattice Model

A theory of mechanical behaviour of the magneto‐sensitive elastomers is developed in the framework of a linear elasticity approach. Using a regular rectangular lattice model, different spatial distributions of magnetic particles within a polymer matrix are considered: isotropic, chain‐like and plane‐like. It is shown that interaction between the magnetic particles results in the contraction of an elastomer along the homogeneous magnetic field. With increasing magnetic field the shear modulus, G, for the shear deformation perpendicular to the magnetic field increases for all spatial distributions of magnetic particles. At the same time, with increasing magnetic field the Young's modulus, E, for tensile deformation along the magnetic field decreases for both chain‐like and isotropic distributions of magnetic particles and increases for the plane‐like distribution of magnetic particles.

     

Holographic Roberge-Weiss transitions

We investigate \( \mathcal{N} = 4 \) SYM coupled to fundamental flavours at nonzero imaginary quark chemical potential in the strong coupling and large N limit, using gauge/gravity duality applied to the D3-D7 system, treating flavours in the probe approximation. The interplay between \( {\mathbb{Z}_N} \) symmetry and the imaginary chemical potential yields a series of first-order Roberge-Weiss transitions. An additional thermal transition separates phases where quarks are bound/ unbound into mesons. This results in a set of Roberge-Weiss endpoints: we establish that these are triple points, determine the Roberge-Weiss temperature, give the curvature of the phase boundaries and confirm that the theory is analytic in μ ² when μ ² ≈ 0.