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171.
Andreas Albrecht Savas Dimopoulos W. Fischler Edward W. Kolb Stuart Raby Paul J. Steinhardt 《Nuclear Physics B》1983,229(2):528-540
A new inflationary universe scenario is considered based upon phase transitions in supersymmetric unified models where the Higgs potential is of the Witten-O'Raifeartaigh type. 相似文献
172.
Thermal behavior of glasses, as observed from the isobaric variations of volume, v, and enthalpy, H, is analyzed in terms of retardation kinetics. A phenomenological theory involving a single retardation time, τ, is developed, assuming that molecular mobility is controlled essentially by the actual free volume, or configurational entropy of the glassy specimen. The characteristic features of the v and H isobars, as derived from the theory, are examined as a function of the thermal history of a typical glassy specimen. The respective contributions of temperature and structural parameters to τ, are also discussed in terms of the characteristic parameters of the isobars. The theoretical predictions are compared with some dilatometric data obtained with an atactic polystyrene. The comparison reveals the limitations of the theoretical treatment and suggests that glass-transition phenomena involve more than one retardation mechanism. 相似文献
173.
The rotational spectrum of the unstable molecule selenoacetaldehyde, CH3CHSe, has been studied by microwave spectroscopy between 26.5 and 40 GHz. Transitions have been measured for five abundant selenium isotopic variants. These measurements have, together with structural information from the related molecules CH3CHS and CH3CHO, allowed reliable data on the C=Se bond length (1.758 ± 0.01 Å) and the
e angle (125.7 ± 0.3°) to be derived. The spectral lines show splittings due to hindered internal rotation and using these together with the derived structure, barrier heights of 1602 cal mole−1 (6703 J mole−1) and 1648 cal mole−1 (6859 J mole−1) have been determined for the ground and first torsionally excited states, respectively. 相似文献
174.
Arthur S. Hyman Stuart I. Yaniger Joel F. Liebman 《International journal of quantum chemistry》1978,14(6):757-766
From the general formalism of elastic x-ray scattering and a few meaningful assumptions we have shown that for an atom, ∫ρ2dτ is an experimentally measurable quantity related to the intensity scattered by an element. We have labeled this quantity (p), the “average electron density.” If ψ obeys the virial theorem, within the Thomas–Fermi approximation we show (within a multiplicative constant) that 〈ρ〉 is a lower bound to (∑ ionization potentials )3/2. Thus, the scattered intensity of x rays is related quantitatively to the energy of the scattering atoms. Inequalities have been developed to express these relationships and have been confirmed for the more exact Hartree–Fock wave functions. 相似文献
175.
176.
Alan L.?CareyEmail author Stuart?Johnson Michael K.?Murray Danny?Stevenson Bai-Ling?Wang 《Communications in Mathematical Physics》2005,259(3):577-613
We develop the theory of Chern-Simons bundle 2-gerbes and multiplicative bundle gerbes associated to any principal G-bundle with connection and a class in H4(BG, ℤ) for a compact semi-simple Lie group G. The Chern-Simons bundle 2-gerbe realises differential geometrically the Cheeger-Simons invariant. We apply these notions to refine the Dijkgraaf-Witten correspondence between three dimensional Chern-Simons functionals and Wess-Zumino-Witten models associated to the group G. We do this by introducing a lifting to the level of bundle gerbes of the natural map from H4(BG, ℤ) to H3(G, ℤ). The notion of a multiplicative bundle gerbe accounts geometrically for the subtleties in this correspondence for non-simply connected Lie groups. The implications for Wess-Zumino-Witten models are also discussed.The authors acknowledge the support of the Australian Research Council. ALC thanks MPI für Mathematik in Bonn and ESI in Vienna and BLW thanks CMA of Australian National University for their hospitality during part of the writing of this paper. 相似文献
177.
A novel swept-laser-based Fourier-domain optical coherence tomography system using an electro-optic phase modulator was demonstrated. The imaging range was doubled by cancellation of the mirror image. The elimination of low-frequency noises resulting from dc and autocorrelation terms increased the sensitivity by 20 dB. 相似文献
178.
We have measured the maximum field for which vortices are completely expelled from a thin-film superconducting strip. Niobium strips of width W were field cooled and imaged with a scanning Hall-probe microscope. Below a critical field B(m) approximately Phi(0)/W(2) all flux was expelled; above this field vortices were observed with a density increasing approximately linearly with field. The small value of the critical field, which is orders of magnitude less than in the bulk, implies that superconducting devices should be designed with narrow wires to eliminate the generation of noise from vortex motion. 相似文献
179.
180.
10,25-Di-tert-alkyl-14,21-dimethyl-3,6,14,21-tetraazatricyclo[21.3.1.18,12]octacosa-1(27),2,6,8,10,12(28),23,25-octaene-27,28-diol macrocycles form Ni(II) and Cu(II) complexes in which the metal cation and the sulfate anion are bound in separated sites in a zwitterionic form of the ligand. The nonyl-substituted macrocycle shows a higher affinity for SO(4)(2-) and a lower binding strength for Cu(2+) than open chain analogues, the pH-dependences for which fall in ranges which allow loading of CuSO(4) at pH approximately 4 and easy stripping to recycle the ligand. X-Ray structure determinations of the Cu(II) and Ni(II) sulfate complexes of the tert-butyl substituted ligand suggest that the de-tuning of M(2+)-binding results from a distortion from planarity of the "salen" N(2)O(2)(2-) donor set imposed by the incorporation of the hexamethylene strap in the ligand and reveal that the sulfate is bound as a hydrate in a 2:2:2:2, ligand-M(2+)-SO(4)(2-)-H(2)O, assembly. 相似文献