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961.
Reinhard Wolf 《Israel Journal of Mathematics》1999,110(1):125-151
The average distance theorem of Gross implies that for each realN-dimensional Banach space (N≥2) there is a unique positive real numberr(E) with the following property: For each positive integern and for all (not necessarily distinct)x
1,x
2, …,x
n inE with ‖x
1‖=‖x
2‖=…=‖x
n‖=1, there exists anx inE with ‖x‖=1 such that
The main result of this paper shows, thatr(E)≤2−1/N for each realN-dimensional Banach spaceE (N≥2) with the so-called quasihypermetric property (which is equivalent toE isL
1-embeddable). Moreover, equality holds if and only ifE is isometrically isomorphic to ℝ
N
equipped with the usual 1-norm. 相似文献
962.
Fusion of bilayer membranes is studied via dissipative particle dynamics (DPD) simulations. A new set of DPD parameters is introduced which leads to an energy barrier for flips of lipid molecules between adhering membranes. A large number of fusion events is monitored for a vesicle in contact with a planar membrane. Several time scales of the fusion process are found to depend exponentially on the membrane tension. This implies an energy barrier of about 10k(B)T for intermembrane flips and a second size-dependent barrier for the nucleation of a small hemifused membrane patch. 相似文献
963.
Alexander Schindler Reinhard K nig Thomas Herrmannsd rfer 《Physica B: Condensed Matter》2000,280(1-4):247-248
Superconductivity of compressed, high-purity platinum powder (average grain size 2–3 μm) was found by measurements of resistivity, AC susceptibility and magnetization. The transition temperature into the superconducting state Tc and the critical magnetic field Bc strongly depend on the packing fraction f of the samples: we found 0.62Tc(0)1.38 mK and 6.6Bc(0)67 μT for 0.8f0.5, respectively. The temperature dependence of the critical magnetic fields can be described by Bc(T)=Bc(0)(1−(T/Tc)2). The discussion of these results includes possible explanations for the origin of superconductivity in this new superconducting material. 相似文献
964.
Reinhard Folk 《Entropy (Basel, Switzerland)》2021,23(2)
The Conferences of the Middle European Cooperation in Statistical Physics (MECO) were created as an attempt to establish and maintain an exchange between scientists in the fields of statistical and condensed matter physics from Western and Eastern countries, overcoming the hurdles of the Iron Curtain. Based on personal remembrance and historical resources, the genesis and further development of MECO meetings is described. The annual meetings were interrupted in 1991 by the Yugoslav War but were re-established in 1993 and continue today. Although the fall of the Iron Curtain and the European Research programs changed the situation for the meetings considerably, the ties created by MECO still are useful to help scientific exchange. The history of European (and not only) statistical physics and the history of the MECO are tightly intertwined. It started in a time where an essential breakthrough has been achieved in statistical physics describing the features near phase transitions. In addition to the merging of solid-state physics and field theory concepts, the application of numerical methods (Monte Carlo methods) added a new pillar besides exact solutions and experiments to check theoretical models. In the following, the scientific emphasis (in general) has changed from the traditional fields of the first MECO to complexity and interdisciplinary themes as well. 相似文献
965.
We discuss an implementation of the self-interaction correction for the local-density approximation to time-dependent density-functional theory. A variational formulation is given, taking care of the necessary constraints. A manageable and transparent propagation scheme using two sets of wave functions is proposed and applied to laser excitation with subsequent ionization of a dimer molecule. 相似文献
966.
Reinhard F. Werner 《Frontiers of Physics》2016,11(3):110305
We describe a setup for obtaining uncertainty relations for arbitrary pairs of observables related by a Fourier transform. The physical examples discussed here are the standard position and momentum, number and angle, finite qudit systems, and strings of qubits for quantum information applications. The uncertainty relations allow for an arbitrary choice of metric for the outcome distance, and the choice of an exponent distinguishing, e.g., absolute and root mean square deviations. The emphasis of this article is on developing a unified treatment, in which one observable takes on values in an arbitrary locally compact Abelian group and the other in the dual group. In all cases, the phase space symmetry implies the equality of measurement and preparation uncertainty bounds. There is also a straightforward method for determining the optimal bounds. 相似文献
967.
We investigate the electronic and ionic dynamics of Na clusters under the influence of a laser pulse in the range 100 femtoseconds
to picoseconds. The dynamics is described by means of the time-dependent local-density approximation coupled to ionic molecular
dynamics (TDLDA-MD). Variation of pulse length allows us to explore the time scales of ionic motion in a manner similar to
pump and probe experiments. Resonant enhancement of electron emission serves as a measure for the time scale of Coulomb explosion.
Received: 3 July 2001 / Published online: 10 October 2001 相似文献
968.
F. Fehrer P. M. Dinh M. Bär P.-G. Reinhard E. Suraud 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):447-458
We investigate the dynamical evolution of a Na8 cluster embedded in Ar matrices of various sizes from N=30 to 1048.
The system is excited by an intense short laser pulse leading to high
ionization stages.We analyze the subsequent highly non-linear motion of cluster and Ar environment in terms of trajectories,
shapes, and energy flow.
The most prominent effects are: temporary stabilization of high charge states for several ps, sudden stopping of the Coulomb
explosion of the embedded Na8
clusters associated with an extremely fast energy transfer to the Ar
matrix, fast distribution of energy throughout the Ar layers by a sound wave.
Other ionic-atomic transfer and relaxation processes proceed at slower
scale of few ps. The electron cloud is almost thermally decoupled
from ions and thermalizes far beyond the ps scale. 相似文献
969.
Atomic-scale surface demixing in a eutectic liquid BiSn alloy 总被引:1,自引:0,他引:1
Shpyrko OG Grigoriev AY Streitel R Pontoni D Pershan PS Deutsch M Ocko B Meron M Lin B 《Physical review letters》2005,95(10):106103
Resonant x-ray reflectivity of the surface of the liquid phase of the Bi(43)Sn(57) eutectic alloy reveals atomic-scale demixing extending over three near-surface atomic layers. Because of the absence of an underlying atomic lattice which typically defines adsorption in crystalline alloys, studies of adsorption in liquid alloys provide unique insight on interatomic interactions at the surface. The observed composition modulation could be accounted for quantitatively by the Defay-Prigogine and Strohl-King multilayer extensions of the single-layer Gibbs model, revealing a near-surface domination of the attractive Bi-Sn interaction over the entropy. 相似文献
970.