Segmentation under geometrical conditions using geodesic active contours and interpolation using level set methods

Let I: be a given bounded image function, where is an open and bounded domain which belongs to ⁿ. Let us consider n=2 for the purpose of illustration. Also, let S={x_i}_i be a finite set of given points. We would like to find a contour , such that is an object boundary interpolating the points from S. We combine the ideas of the geodesic active contour (cf. Caselles et al. [7,8]) and of interpolation of points (cf. Zhao et al. [40]) in a level set approach developed by Osher and Sethian [33]. We present modelling of the proposed method, both theoretical results (viscosity solution) and numerical results are given. AMS subject classification 49L25, 74G65, 68U10     

Über die π-Elektronenstruktur der 1,2-Dipyridyl-äthylene, 2. Mitt.: Die Spektralübergänge

Zusammenfassung Es werden die charakteristischen Größen der Spektralübergänge der 1,2-Dipyridyl-äthylene berechnet und an Hand des Vergleichs mit gemessenen Werten diskutiert.Mit 1 Abbildung     

Phenomenological analysis of the linear magnetic birefringence in dysprosium iron garnet

Experimental data on linear magnetic birefringence (LMB), previously reported at 1.15 μm wavelength in the 4.2-300 K temperature range and with an applied field up to 20 kOe, in dysprosium iron garnet (DyIG) are analyzed in terms of electric dipole transition within the three magnetic sublattices. Assuming that the garnet symmetry is cubic and that the contribution of the Fe³⁺ ions to LMB is the same as yttrium iron garnet (YIG), the 2nd order magneto-optical (MO) coefficient (Γ₂) of the Dy³⁺ ions is deduced. In the spontaneous state, Γ₂ is linear temperature dependent as previously found for the 1st order (MO) coefficient. It is shown that Γ₂ must be field dependent to explain the evolution of the LMB.     

Échanges inter et intra-molćulaires du proton entre deux atomes d'azote de cycles chélatés hydrazone-imine et azo-énamine

Inter- and intra-molecular exchanges of chelated proton are evaluated by NMR in arylhydrazones derived from β-keto-imines and β-diimines.     

Numerisch-theoretisch und experimentelle Untersuchung einer Hochstrom-Fernfokus-Elektronenkanone vom Tetroden-Typus

Starting from a earlier investigation of a telefocus-electron gun of the triode-type (Z. angew. Phys.11, 370 (1950) which however was unable to deliver high beam currents, a telefocus-gun of the tetrode-type for high beam currents was theoretically and experimentally investigated and the main results are presented in this paper. In the first part of this work a model-system has been investigated by numerical-theoretical methods to get an idea of the electron paths inside the gun as well as to estimate the highest obtainable perveance of the gun. In these investigations an analogy-resistance-network for the plotting of potential fields and an electronic computer for the electron path calculations have been used. These calculations showed that an electron-gun of small geometrical dimensions can be built which is able to focus high beam currents at long distances from the cathode. The relevant gung parameters are a short distance from cathode to first-anode and a high negative Wehnelt-potential. In the second part of the paper the results of some experimental investigations are reported. The experiments showed that by suitable dimensioning a 50 mA, 20 kV electron beam can be focussed in a crossover of some few tenths of mm diameter at a distance of 150–250 mm from the cathode. Some examples for the gun data are given. The aberrations of the electron gun are considerable at the higher currents: At 20 kV one can easily obtain a beam current of 150 mA with a cathode of 2 mm diameter. The aberrations influence infavourably the current density distribution in the crossover. The disturbance is especially noticeable for long cathode to focus distances as was the case in some reported experiments with a cathode to focus distance of 410 mm.The described telefocus-gun has been used for electron beam welding and some practical conclusions of these experiments are discussed in the paper.

---

---

Leicht gekürzte Fassung eines Vortrages an der Second International Conference on Electron and Ion Beam Science and Technology, New York, April 17–20, 1966.     

Gravity induced vortices and stepwise growth of these vortices in vertical counterflow of liquid helium

Detailed measurements of the second sound excess attenuation in vertical counterflow show the existence of a zero critical velocity and of steps which can be interpreted as a Josephson A.C. effect related to vortex motion.     

Effets de cryptands et activation de bases—II: Genese d'enolates et essais d'activation de LiH,NaH et KH dans l'ether,le THF et le benzene

The generation of the lithium, sodium and potassium enolates of cyclohexanone using LiH, NaH and KH has been investigated. The utilization of macrocyclic ligands (which selectively complex the metal cation) activated the alkaline hydride reagent. However, the most dramatic effect was the activation of the enolate, enabling proton abstraction from the solvent.