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91.
When considering strangelets at finite temperature it is important to obey the constraint that any observed state must be color singlet. This constraint results in an increase in strangelet masses as calculated at fixed entropy per baryon. We use the color singlet partition function for an MIT bag, derived using the group theoretical projection method, to calculate strangelet masses. Mean shell effects are included in a liquid drop model, by using a density of states obtained from the multiple reflection expansion. Another important effect of the color singlet restriction, namely many orders of magnitude suppression of thermal nucleation of quark-gluon plasma in collisions, will also briefly be described. 相似文献
92.
Gortler A. Schwandner A. Christiansen J. Frank K. Granzer H. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(5):516-521
The pseudospark, a low-pressure gas discharge in a special geometry, is suitable for high-current switching. A single-channel prototype is tested with a 3.3-μF capacitor bank, voltages up to 30 kV, and peak currents up to 120 kA. The electrical circuit, not comprising any load resistor causes weakly damped sinusoidal pulses of 5-μs duration at 90% current reversal. For lifetime tests, a switch with an alumina insulator and copper seals is used. Hydrogen is the working gas. Several electrode materials like molybdenum, tungsten, graphite and chromium-copper are tested. Optical investigations of the discharge and of plasma parameters are done with an O-ring sealed pseudospark switch. The light of the discharge is observed spectrally integrated with a streak camera. Spectral resolution is obtained by using a high-speed shutter in combination with a monochromator. The radial electron density is determined by measuring the Stark broadening of the Balmer Hβ-line. At 60 kA a maximum electron density of about 2×1017cm-3 is calculated 相似文献
93.
Christiansen O 《The Journal of chemical physics》2005,122(19):194105
A formalism for deriving and implementing response functions for vibrational wave functions is described. The formalism utilizes a recently developed second-quantization formulation of many-mode dynamics to define nonredundant parameterizations for different types of approximate vibrational wave functions. The derived response functions cover the cases of an exact state, a vibrational self-consistent field state, and a vibrational configuration interaction state. Sample calculations are presented for the linear-response function and response excitation energies for a two-mode model system and for formaldehyde employing a quartic force field. The advantages and disadvantages of the response theoretical approach for describing excitation energies using different parameterizations are discussed. 相似文献
94.
A simplicial mesh on an oriented two-dimensional surface gives rise to a complex of finite element spaces centered on divergence conforming Raviart–Thomas vector fields and naturally isomorphic to the simplicial cochain complex. On the barycentric refinement of such a mesh, we construct finite element spaces forming a complex , centered around curl conforming vector fields, naturally isomorphic to the simplicial chain complex on the original mesh and such that is in duality with . In terms of differential forms this provides a finite element analogue of Hodge duality. To cite this article: A. Buffa, S.H. Christiansen, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
95.
The dispersion and damping of whistler waves has been measured in an essentially collisionless plasma at frequencies up to 0.92ωc, the electron cyclotron frequency. The experimental results agree to within ± 10% of the plane wave hot plasma dispersion relation. 相似文献
96.
W. Busse J. Christiansen D. Hilscher U. Morfeld J. A. Scheer W. U. Schr der 《Nuclear Physics A》1967,100(3):490-496
The angular dependence of the polarization of neutrons from the reaction 3H(d, n)4He was measured at deuteron energies of 3.35, 4.35 and 5.35 MeV for reaction angles up to 165° lab. Polarization values were derived from the left-right asymmetry in n- scattering. 相似文献
97.
A single fluxon on a semi-infinite Josephson line is reflected at a passive or an active termination. By numerical computation we find a single reflected fluxon, an antifluxon, absorption of the incident fluxon, or fission into an arbitrary number of fluxons depending on the boundary condition. For the passive termination an analytical approximation based on energy analysis is developed. 相似文献
98.
99.
An efficient route to (Z)-(8-benzyloxy-8-oxooct-3-en-1-yl)triphenylphosphonium iodide, or BOTPPI, is disclosed, complete with full experimental details, NMR spectra, and HRMS data. BOTPPI serves as a surrogate for (Z)-(8-methoxy-8-oxooct-3-en-1-yl)triphenylphosphonium iodide, or MOTPPI, a Wittig salt previously used in two 12-HETE syntheses. BOTPPI has the advantage over MOTPPI of being derived from a sequence for which every intermediate is UV-active and amenable to large-scale chromatographic purification. A formal asymmetric total synthesis of 12-(S)-HETE is also reported, involving a stereoselective phase-transfer catalyzed (PTC) alkylation in its key step. 相似文献
100.
Snorre H. Christiansen 《Numerische Mathematik》2011,119(4):613-640
We study the linearization of three dimensional Regge calculus around Euclidean metric. We provide an explicit formula for
the corresponding quadratic form and relate it to the curl t curl operator which appears in the quadratic part of the Einstein–Hilbert action and also in the linear elasticity complex.
We insert Regge metrics in a discrete version of this complex, equipped with densely defined and commuting interpolators.
We show that the eigenpairs of the curl t curl operator, approximated using the quadratic part of the Regge action on Regge metrics, converge to their continuous counterparts,
interpreting the computation as a non-conforming finite element method. 相似文献