Plasma losses in a toroidal theta-pinch with superposed hexapole

A toroidal theta-pinch discharge with superposed non-helical hexapole field is investigated. The characteristic data of the discharge are: major diameter 52 cm, minor inner diameter of the vacuum vessel 6 cm, maximum magnetic field between 10 and 21 kG, rise time (quarter-cycle) 3.0 μs, maximum temperature between 40 and 100 eV, maximum density between 1 and 3×10¹⁶ cm^?3, beta-values between 0.3 and 1. The plasma confinement times are determined by measuring particle density, temperature and plasma radius. The confinement times are compared with those of models which account for cusp losses, resistive losses, and Bohm diffusion. Measured confinement times are consistent with those expected from cusp losses with a cusp slit-width of one ion gyro-radius. Above electron temperatures of 20 eV, resistive losses are negligible. Bohm diffusion is not consistent with measurements, but is of the same order of magnitude.     

Constraint Programming Based Column Generation for Crew Assignment

Airline crew assignment problems are large-scale optimization problems which can be adequately solved by column generation. The subproblem is typically a so-called constrained shortest path problem and solved by dynamic programming. However, complex airline regulations arising frequently in European airlines cannot be expressed entirely in this framework and limit the use of pure column generation. In this paper, we formulate the subproblem as a constraint satisfaction problem, thus gaining high expressiveness. Each airline regulation is encoded by one or several constraints. An additional constraint which encapsulates a shortest path algorithm for generating columns with negative reduced costs is introduced. This constraint reduces the search space of the subproblem significantly. Resulting domain reductions are propagated to the other constraints which additionally reduces the search space. Numerical results based on data of a large European airline are presented and demonstrate the potential of our approach.     

Theory of nuclear fission by stopped pions

Nuclear fission by stopped pions is analyzed in a two-step model in which the pion is absorbed on a nucleon pair, followed by the prompt emission of one nucleon and compound nucleus formation by the other. This simple picture yields agreement with observed prompt neutron spectra and average nucleon multiplicities. The analysis of nuclear fission in a statistical framework is shown to provide valuable corroboration of the expected properties of a highly excited compound nucleus and of our understanding of the pion absorption mechanism. The ratio of fission to neutron level density parameters is shown to exceed unity in all cases studied.     

Simple determination of 22 organophosphorous pesticides in human blood using headspace solid-phase microextraction and gas chromatography with mass spectrometric detection

A simple and rapid procedure for the determination of 22 organophosphorous pesticides (bromophos-ethyl, bromophos-methyl, chlorfenvinphos, chlorpyriphos, demethon-S-methylsulfon, diazinon, dichlorvos, dicrotophos, dimethoate, disulfoton, edifenphos, fenitrothion, fenthion, malathion, methidathion, mevinphos, monocrotophos, omethoate, parathion-ethyl, parathion-methyl, phosphamidon, and quinalphos) in human blood using headspace (HS) solid-phase microextraction (SPME) and gas chromatography (GC)-mass spectrometry (MS) is presented. The effects of various sample additions, incubation temperatures, absorption times, desorption times, and depths of fiber insertion into the injection port of the GC are optimized to enhance the sensitivity of the procedure. The recoveries of spiked blood samples are determined between 70% and 95% compared with samples prepared in water, and absolute recoveries are in the range between 0.1% and 19.6%. For quantitation in the single ion monitoring mode, linearity is established over concentration ranges from 0.025 to 5.0 microg/g with excellent coefficients of correlation (0.991-0.998). The detection limits are in the range between 0.01 and 0.3 microg/g. The time for analysis is 44 min per sample including extraction and GC-MS analysis. HS-SPME in combination with GC-MS is an effective method for the determination of organophosphorous pesticides in human blood and shows a great potential for use in rapid on-site analytical work, which is highly demanded in clinical and forensic toxicology.     

Complex coordinate calculations of resonances in N-electron atoms

We present a discussion of the functional dependences of the wave functions for bound, resonant, and scattering states on the radial coordinate ρ and the rotation angle α in the complex coordinate method. We conclude that for bound states and resonances, ρ and α are constrained to appear in the wave functions only in the for ρ exp(iα). On the other hand, this constraint is not obtained for the scattering states since the energy of the scattering states depends on α. In addition we suggest a partitioning of the resonant wave function into two parts—a boundlike or “Q-space” part and a scattering like or “P-space” part. With these concepts one can incorporate physical insight into the choice of configurations as one does in other methods and can apply the complex coordinate method to many electron systems with an expected rate of convergence similar to other techniques. Its advantages are that a single calculation yields the position and width of the resonance, only square integrable functions are used, only a solution of a straightforward eigenvalue problem is required unlike some methods, arbitrarily accurate target states are easily incorporated, and polarization terms can easily be explicitly included. Variational calculations for the position and width of the lowest ²S resonance in the negative helium ion are reported using trial wave functions containing 39, 43, 55, 24, and 32 “P-space” configurations, respectively. Values of 19.387 eV and 12.13 meV are obtained for the position and width, respectively, for the resonance over a range in the rotation angle of almost two orders of magnitude. One also finds that inclusion of free-particle-like basis functions improves the representation of the scattering states.     

Remarks on the Magnetic Top

We revisit via a path-integral approach the magnetic top proposed recently by Barut, Boi, and Mari. We point out that the magnetic top has the SU(2) symmetry and that it can be viewed as a free top seen from a rotating frame. We present an alternative path-integral quantization of the magnetic top on the basis of the symmetry, and show that the magnetic coupling does not participate in altering the spin quantum numbers.     

Zum Nachweis von Melasse in Trockenschnitzeln

Ohne Zusammenfassung     

Fehlerquellen und Ungenauigkeiten bei Oberflächenspannungsmessungen mittels der Tropfapparate

Zusammenfassung Beim Eintauchen der Tropfenz?hl- oder -me\apparate in die zu untersuchende Flüssigkeit bleibt an der Au\enfl?che der R?hren Flüssigkeit h?ngen, die im Laufe der Messung an die Abtropffl?che herabsickert, mit den sich bildenden Tropfen zusammenflie\t und so die Tropfenbildung st?rt. Die entstehenden Fehler k?nnen unter Umst?nden enorm gro\ sein. Diese Unregelm?\igkeiten sind leicht und restlos zu vermeiden, wenn man die Abtropfr?hren der Apparate zwischen dem Hochsaugen der Flüssigkeit und dem Beginn der Messung in der angegebenen Weise gründlich abwischt.