作者机构：
[Yang, CB] Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;KFKI, RMKI, Div Theory, H-1525 Budapest 114, Hungary.
通讯机构：
[Yang, CB] H;Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
It is suggested that the study of multiplicity difference correlators between two well-separated bins in high-energy heavy-ion collisions can be used as a means to detect evidence of a quark-hadron phase transition. Analytical expressions for the scaled factorial moments of multiplicity difference distribution are obtained for small bin size with mean multiplicity s¯<~0.3 within Ginzburg-Landau description. It is shown that the scaling behaviors between the moments are still valid, though the behaviors of the moments with respect to the bin size are completely different from the so-called intermittency patterns. A universal exponent γ is given to describe the dynamical fluctuations in the phase transition.
摘要：
The information on dynamical fluctuations that can be extracted from the anomalous scaling observed recently in hadron-hadron collision experiments is discussed in some detail. A parameter "effective fluctuation strength" is proposed to estimate the strength of dynamical fluctuations. The method for extracting its value from the experimentally observed quantities is given. Some examples for the application of this method to real experimental data are presented. (C) 1998 Elsevier Science B.V. All rights reserved.
摘要：
Passive and active fiber probes, used for the scanning near-field optical microscope (SNOM), show different image properties. For the passive fiber probe, a better optical image contrast has been obtained with a parabolic taper than with a linear taper. The reflected fields in different fiber tapers have been discussed. For the active fiber probe, an ASE (Amplified Spontaneous Emission) probe made of Er<sup>3+</sup>-doped fiber has shown a higher efficiency of several times and a lower image noise than the usual passive probe.
摘要：
The effects of the Blandford-Znajek (BZ) process on the evolution of the central black holes of accretion discs are investigated by an analytical method and numerical calculations in this paper. It is shown that the BZ process reduces the rates of change of some parameters of the black hole, such as mass, angular momentum, dimensionless angular momentum and temperature, and the evolution of the central black hole towards the extreme Kerr black hole is depressed effectively. However, the rate of change of entropy of the central black hole is augmented in the BZ process. In addition, the consistency of the BZ process with the three laws of black hole thermodynamics is discussed.
摘要：
The complete charge distribution of products from Au nuclei fragmenting in nuclear emulsion at 10.7A GeV has been measured. Multiplicities of produced particles and particles associated with the target source are used to select peripheral and central events. A statistical analysis, based on event-by-event charge distributions, show that a population of subcritical, critical and supercritical events, i.e. a phase transition like behaviour, is observed among peripheral collisions.
期刊：
PHOSPHORUS SULFUR AND SILICON AND THE RELATED ELEMENTS,1998年132(1):147-153 ISSN：1042-6507
通讯作者：
He, LN
作者机构：
[He, LN] Cent China Normal Univ, Inst Organ Synth, Wuhan 430079, Peoples R China.;Nankai Univ, Inst Elementoorgan Chem, Tianjin 300071, Peoples R China.
通讯机构：
[He, LN] C;Cent China Normal Univ, Inst Organ Synth, Wuhan 430079, Peoples R China.
摘要：
Abstract Lawesson's reagent reacted with phenylthiourea in toluene at 110°C to give a product of ring-opening (2) instead of a 4-membered ring 2a. Its structure was determined by X-ray diffraction analysis. A mechanism is proposed to explain the formation of compound 2. The O-S exchange reaction of Lawesson's reagent with oxamide in acetonitrile was also investigated.
摘要：
Membrane catalytic deprotonation of water (water splitting) has been studied on the base of a new model which suggests that water molecules are prepolarized by H<sup>+</sup>-affinited and OH<sup>-</sup>-affinited fixed charged groups of membrane before their dissociation is enhanced by electric field. Introducing some anion selective groups such as Mg(OH)<inf>2</inf>·xH<inf>2</inf>O or amine into a cation selective perfluorosulfonated membrane can initiate a dramatic water splitting effect and give rise to new high frequency peaks on the OH and OD stretching region of IR spectra. This supports the hypothesis that some water molecules were affected by the surrounding electrical field from the bipolar membrane-like structure. Perfluorocarboxylic membrane was also tested in a electrolytic cell and it causes H<sup>+</sup> ion fluxes much larger than Nafion-type membrane. We classify the effect as membrane catalytic deprotonation of carboxylic acid group.
关键词：
finite-size effects;phi(4) theory;upper critical dimension;five-dimensional Ising model
摘要：
We present a perturbative calculation of finite-size effects near $T_c$ of the $\phi^4$ lattice model in a $d$-dimensional cubic geometry of size $L$ with periodic boundary conditions for $d > 4$. The structural differences between the $\phi^4$ lattice theory and the $\phi^4$ field theory found previously in the spherical limit are shown to exist also for a finite number of components of the order parameter. The two-variable finite-size scaling functions of the field theory are nonuniversal whereas those of the lattice theory are independent of the nonuniversal model parameters.One-loop results for finite-size scaling functions are derived. Their structure disagrees with the single-variable scaling form of the lowest-mode approximation for any finite $\xi/L$ where $\xi$ is the bulk correlation length. At $T_c$, the large-$L$ behavior becomes lowest-mode like for the lattice model but not for the field-theoretic model. Characteristic temperatures close to $T_c$ of the lattice model, such as $T_{max}(L)$ of the maximum of the susceptibility $\chi$, are found to scale asymptotically as $T_c - T_{max}(L) \sim L^{-d/2}$, in agreement with previous Monte Carlo (MC) data for the five-dimensional Ising model. We also predict $\chi_{max} \sim L^{d/2}$ asymptotically. On a quantitative level, the asymptotic amplitudes of this large -$L$ behavior close to $T_c$ have not been observed in previous MC simulations at $d = 5$ because of nonnegligible finite-size terms $\sim L^{(4-d)/2}$ caused by the inhomogeneous modes. These terms identify the possible origin of a significant discrepancy between the lowest-mode approximation and previous MC data. MC data of larger systems would be desirable for testing the magnitude of the $L^{(4-d)/2}$ and $L^{4-d}$ terms predicted by our theory.
关键词：
finite-size scaling;phi(4) field theory;upper critical dimension;five-dimensional Ising model
摘要：
We demonstrate that the standard O(n) symmetric phi(4) field theory does not correctly describe the leading finite-size effects near the critical point of spin systems with periodic boundary conditions on a d-dimensional lattice with d > 4. We show that these finite-size effects require a description in terms of a lattice Hamiltonian. For n --> infinity and n = 1, explicit results are given for the susceptibility and for the Binder cumulant. They imply that these quantities do not have the universal properties predicted previously and that recent analyses of Monte Carlo results for the five-dimensional Ising model are not conclusive.
摘要：
In this paper, unified colored noise approximation is extended to treat the systems driven by Poisson colored noise cursive Greek chi = υ(cursive Greek chi) + gξcp(t). We arrive the evolution equation of the probability distribution Pi(cursive Greek chi, τ) and the stationary probability distribution ps(cursive Greek chi, τ). These equations are valid only if r(cursive Greek chi, τ) ≡ τ-1/2[1 - τG(cursive Greek chi)/g(cursive Greek chi)] (G(cursive Greek chi) ≡ υ′(cursive Greek chi)g(cursive Greek chi) - υ(g)g′(cursive Greek chi)) is large enough (positive) and t ≫ τ/τ(cursive Greek chi, τ), but r is not restricted. As an application, we derive the nonlinear relaxation time (NLRT) for the processes driven by Poisson colored noise and evaluate the NLRT for the approximative Ginzburg-Landon model under small τ.
期刊：
INTERNATIONAL JOURNAL OF MODERN PHYSICS A,1998年13(12):1969-1979 ISSN：0217-751X
通讯作者：
Feng, L
作者机构：
[Feng, L] Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Feng, L] H;Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
According to the cone definition of the jet we propose a practical and effective algorithm to identify jets. Through comparison between the Monte Carlo samples with and without jet(s), the following observations are made. Contrary to what is expected, most of the jetty events do not have high multiplicity. The distributions of multiplicity and (p) over bar t have long tails for the whole event sample because of (mini)jet production, but no such tail for a no-jet event subsample. The average transverse momentum per event (p) over bar t and multiplicity n are positively correlated for the whole event sample, and negatively correlated for the jetty event subsample. Two ratios are introduced to describe the "degree of hardness" of each event and are found to be correlated positively with (p) over bar t, but negatively with multiplicity, indicating that (p) over bar t is a better characteristic parameter to describe the event hardness than multiplicity.
作者机构：
[Yang, GF] Cent China Normal Univ, Inst Organ Synth, Wuhan 430079, Hubei, Peoples R China.;Nankai Univ, State Key Lab, Tianjin 300071, Peoples R China.;Nankai Univ, Inst Elementoorgan Chem, Tianjin 300071, Peoples R China.
通讯机构：
[Yang, GF] C;Cent China Normal Univ, Inst Organ Synth, Wuhan 430079, Hubei, Peoples R China.
摘要：
The herbicidal activities of a series of 1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonanilides containing various substituents on the benzene ring were quantitatively analyzed with physicochemical parameters by using Hansch-Fujita method. Variations in the activity were parabolically related to electronic parameters with the optimum pKa value being about 6.93. The hydrophobic factor in addition to the electronic property seemed to have important effect on the activity.
摘要：
The dimensional regularization is applied to three-loop vacuum graphs in massless QED to evaluate temperature-dependent ultraviolet divergences and infrared divergences in arbitrary covariant gauge. They both are shown to be absent due to cancellations among themselves, and the cancellations are gauge-independent although the individual divergences are gauge-dependent.
作者机构：
[Hu, XM; Peng, JS] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hu, XM] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
We investigate the effect of some incoherent steps on the intensity fluctuations in the four-level Lambda quantum-beat laser. It is demonstrated that such a four-level system can produce a squeezed two-mode laser. For the light coming out of this device we may achieve up to 50% intensity noise reduction. A simple physical explanation of the squeezing mechanism for two-mode squeezing is given. (C) 1998 Elsevier Science B.V. All rights reserved.
作者机构：
[Huang, GM; Peng, JS; Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Li, GX] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
We have investigated the atomic coherent population trapping in a multilevel laser-induced continuum structure system including cascade two-photon processes, in which two sets of quasicontinua of excited levels to be modeled as the Bixon-Jortner quasicontinuum are laser-embedded into a previously structureless atomic continuum. The condition leading to the atomic coherent population trapping and the coherent population trapping state are given explicitly. And the effects of the Fano factors, the laser intensities and the detunings on the amount of population trapped in the atomic bound states and the populations distributed in the two sets of quasicontinua are also examined.
