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Nernst R Antreasyan D Aschman D Besset D Bienlein JK Bloom ED Brock I Cabenda R Cartacci A Cavalli-Sforza M Clare R Conforto G Cooper S Cowan R Coyne D de Judicibus D Edwards C Engler A Folger G Fridman A Gaiser J Gelphman D Godfrey G Heimlich FH Hofstadter R Irion J Jakubowski Z Keh S Kilian H Kirkbride I Kloiber T Koch W König AC Königsmann K Kraemer RW Lee R Leffler S Lekebusch R Lezoch P Litke AM Lockman W Lowe S Lurz B Marlow D Maschmann W Matsui T Messing F Metzger WJ Monteleoni B 《Physical review letters》1985,54(20):2195-2198
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The time-dependent creation and annihilation operators for a complex scalar field, in a Friedmann space-time, defining particle states with respect to which the Hamiltonian is diagonal, are related by a Bogoliubov transformation to the creation and annihilation operators defined in strict analogy with the procedure carried out in Minkowski space. The Bogoliubov transformation is here written in terms of a unitary operator,U, and an expression for that operator is found via the generating functionF=i InU. The properties of the representation obtained by makingU act upon the state vector , to give a new state U, are discussed. It is shown that the particle-number operator remains constant in such a picture so that the evolution of the system with time is clearly seen to depend upon the energy k on the one hand, and upon the state vector U on the other. Also, it is pointed out that this new representation permits the in and out states to be defined unambiguously.On leave of absence from Istituto de Fisica G. Galilei (Padova) and Istituto Nazionale di Fisica Nucleare (Sezione di Padova). 相似文献
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Bis[3-(dimethylarsino)propyl]phenylarsine, (tas), reacts with trans-Ir(CO)(EPh3)2 X (E = P, As; X = F, Cl, Br, I) to yield the (Ir(CO)(tas)] X complexes. In contrast, the similar ligand bis[3-(dimethylarsino)propyl]phenylphosphine, (dap), reacts with trans-Ir(CO)(EPh3)2X (E = P, As; X = Cl, Br, I) to yield a mixture of [Ir(CO)(dap)X] and [Ir(CO)(dap)]X, and with trans Ir(CO)(EPh3)2F (E = P, As) to yield solely [Ir(CO)(dap)F]. The cations [Ir(CO)(L)]+ (L = tas, dap) readily yield tetraphenylborate derivatives, [Ir(CO)(L)]BPh4. The oxygenation of [Ir(CO)(tas)]+ in solution proceeds almost to completion after 15 h, whereas [Ir(CO)(dap)]+ does not appear to undergo oxygenation. 相似文献
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Froula DH Divol L Meezan NB Dixit S Moody JD Neumayer P Pollock BB Ross JS Glenzer SH 《Physical review letters》2007,98(8):085001
We demonstrate that a blue (3omega, 351 nm) laser beam with an intensity of 2 x 10(15) W cm(-2) propagates nearly within the original beam cone through a millimeter scale, T(e)=3.5 keV high density (n(e)=5 x 10(20) cm(-3)) plasma. The beam produced less than 1% total backscatter at these high temperatures and densities; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds. 相似文献
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In this paper we extend the plane blow-up results of Grundy& McLaughlin (1997) to the three-dimensional Navier-Stokes equations.Using a solution structure originally due to Lin we first providenumerical evidence for the existence of blow-up solutions on- < x, z < , 0 y 1 with boundary conditions on y = 0and y = 1 involving derivatives of the velocity components.The formulation enables us to consider plane and radial flowas special cases. Various features of the computations are isolatedand are used to construct a formal asymptotic solution closeto blow-up. We show that the numerical and asymptotic analysesprovide a mutually consistent global picture which supportsthe conclusion that, for the family of problems we considerhere, blow-up in fact can take place in three dimensions butat an inverse linear rate rather than the faster inverse squareof the plane case. 相似文献
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Ice nucleating-active Pseudomonas fluorescens F264C was fed to Colorado potato beetles to determine bacterial retentioin in the beetle gut and its effect on the cold hardiness of this insect pest. The bacrterium was present in beetles recovered after overwintering in the field, seven months after their exposure to P. fluorescens. Retention was evident not only in the detection of the P. fluorescens ice nucleating gene, inaW, in bacterial cultures from beetle guts but also in the elevated supercooling points of some treated beetles. 相似文献