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991.
The class of dynamical systems is considered, which are described by several mutually noncommuting Hamiltonian currents, in particular, relativistic bi-Hamiltonian systems, the evolution of which is described by a pair of 4-momenta p and p The examination is conducted in classical and quantum realizations. The evolution equations are derived of relativistic bi-Hamiltonian systems in the Heisenberg and Schrödinger pictures. It is shown that the quantum theory of relativistic bi-Hamiltonian systems is not compatible with the unitary condition and is nonunitary. A physical interpretation is given of nonunitary quantum theory.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 5–12, October, 1990. 相似文献
992.
An ultrabroadband (up to 35 nm FWHM) generation by a pulsed dye laser is reported. The principle of laser operation is based on a recently proposed cavity configuration, which we have termed spatially-dispersive resonator. By means of a prism pair this spreads the various spectral components into different spatial areas in the active medium and thus reduces the competition between them. A generation of a spectrum containing a number of equally spaced lines is also demonstrated. 相似文献
993.
A global existence theorem for the general coagulation–fragmentation equation with unbounded kernels
In this article an existence theorem is proved for the coagulation–fragmentation equation with unbounded kernel rates. Solutions are shown to be in the space X+ = {c∈L1: ∫ (1 + x)∣c(x)∣dx < ∞} whenever the kernels satisfy certain growth properties and the non-negative initial data belong to X+. The proof is based on weak L1 compactness methods applied to suitably chosen approximating equations. 相似文献
994.
I. Palásti 《Periodica Mathematica Hungarica》1989,20(3):231-235
Here we establish a set of eight points in general position in the plane, i.e. no three on a line, no four on a circle, and they determine 7 distinct distances, so that, thei-th distance occursi times,i = 1, 2, , 7. The points are embedded in a triangular net, and the distances are not ordered by size or in any other way. We shall show that some known and unknown examples forn < 8 with the above properties may also be lattice points of a similar net.Research (partially) supported by the Hungarian National Foundation for Scientific Research (OTKA) grant, no. 1808. 相似文献
995.
G. I. Ol'shanskii 《Journal of Mathematical Sciences》1989,47(2):2466-2473
Starting from the universal enveloping algebras u(gl(n)), n=1,2,... we construct an algebra A, which gives a realization of the Yangian Y(gl(m)) and is a proper way to define the universal enveloping algebra for infinite-dimensional classical Lie algebras.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 164, pp. 142–150, 1987. 相似文献
996.
The set of solutions of the equation A(u, )=0 in the case of general position consists of smooth curves. Solutions of a quasilinear elliptic equation with large instability index are constructed and an estimate obtained for the number of turning points of the solution curves.Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 12, pp. 47–58, 1987. 相似文献
997.
One computes the spectral multiplicity of the direct sum of operators of the following form: a unitary operator U=UaUs, a contraction T of class C0, a one-sided shift S, and its conjugate S*. Theorem: where mo=1 if m=0 and mo=0 it m>0.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 157, pp. 23–29, 1987. 相似文献
998.
I. M. Karpman 《Fluid Dynamics》1988,23(1):153-156
The pressure distribution on a cone with a half-angle =75°, from which a single central underexpanded jet issues into a subsonic counterstream, has been experimentally investigated. The effect of the flow regime in the jet on the pressure distribution is demonstrated. Generalized relations for the pressure on the body are obtained for various jet-flow momentum ratios J and flow Mach numbers M = 0.35–0.9; the Mach number Ma at the exit of the conical nozzle with half-angle a=10° was equal to 2.9. The working medium of the jet and the flow was air with stagnation temperatures T0a = T0 260–265°K. The ratio of the nozzle outlet radius to the radius of the maximum cross section of the cone a/RM=0.1.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 182–185, January-February, 1988. 相似文献
999.
S. Bamidele Sanni H. Behm Paul T. Beurskens E. Kayode Adesogan James I. Durodola 《Journal of chemical crystallography》1988,18(5):575-582
A new cytotoxic macrocyclic diterpenoid named Japodagrol, C20H28O4, has been isolated from the ornamental plantJatropha podagrica, family Euphorbiaceae, grown in Nigeria. The structure of the title compound, C20H28O4, was solved by X-ray analysis.M
r
=332.44, monoclinic space groupC2,a=23.285(4),b=6.5105(12),c=12.505(3) Å,=98.504(17),V=1874.8 Å3,Z=4,D
c
=1.178 Mg/m3. CuK radiation (graphite crystal monochromator, =1.54184 A), (CuK)=6.13 cm–1,F(000)=720,T=290 K. Final conventionalR factor=0.035,R
w
=0.038 for 3349 observed reflections. The structure was solved with the programDirdif. The 5-membered ring is closed to a half-chair form. The compound contains inter- and intramolecular hydrogen bonds. 相似文献
1000.