Joint CLT for several random sesquilinear forms with applications to large-dimensional spiked population models

published_or_final_versio

Excitation Energy as a Basic Variable to Control Nuclear Disassembly

Thermodynamical features of Xe system is investigated as functions of temperature and freeze-out density in the frame of lattice gas model. The calculation shows different temperature dependence of physical observables at different freeze-out density. In this case, the critical temperature when the phase transition takes place depends on the freeze-out density. However, a unique critical excitation energy reveals regardless of freeze-out density when the excitation energy is used as a variable insteading of temperature. Moreover, the different behavior of other physical observables with temperature due to different $\rho_f$ vanishes when excitation energy replaces temperature. It indicates that the excitation energy can be seen as a more basic quantity to control nuclear disassembly.Comment: 3 pages, 2 figures, Revte

A Chandra ACIS view of the Thermal Composite Supernova Remnant 3C391

We present a 60 ks Chandra ACIS-S observation of the thermal composite supernova remnant 3C391. The southeast-northwest elongated morphology is similar to that previously found in radio and X-ray studies. This observation unveils a highly clumpy structure of the remnant. Detailed spatially resolved spectral analysis for the small-scale features reveals that the interior gas is generally of normal metal abundance and has approached or basically reached ionization equilibrium. The hydrogen column density increases from southeast to northwest. Three mechanisms, radiative rim, thermal conduction, and cloudlet evaporation, may all play roles in the X-ray appearance of 3C391 as a "thermal composite" remnant, but there are difficulties with each of them in explaining some physical properties. Comparatively, the cloudlet evaporation model is favored by the main characteristics such as the highly clumpy structure and the uniform temperature and density distribution over most of the remnant. The directly measured postshock temperature also implies a young age, about 4 kyr, for the remnant. The postshock gas pressure derived from the NE and SW rims, which harbor maser spots, is consistent with the estimate for the maser regions. An unresolved X-ray source is observed on the northwest border and its spectrum is best fitted by a power-law.Comment: aastex, 27 pages (including 4 figures), to appear in the ApJ 1 Dec. 2004, v616 issu

Quantum lattice fluctuations in a model electron-phonon system

An analytical approach, based on the unitary transformation method, has been developed to study the effect of quantum lattice fluctuations on the ground state of a model electron-phonon system. To study nonadiabatic case, the Green's function method is used to implement the perturbation treatment. The phase diagram and the density of states of fermions are obtained. We show that when electron-phonon coupling constant $\alpha^{2}/K$ decreases or phonon frequency $\omega_{\pi}$ increases the lattice dimerization and the gap in the fermion spectrum decrease gradually. At some critical value the system becomes gapless and the lattice dimerization disappears. The inverse-square-root singularity of the density of states at the gap edge in the adiabatic case disappears because of the nonadiabatic effect, which is consistent with the measurement of optical conductivity in quasi-one-dimensional systems.Comment: 9 pages, 4 ps figures include

Quantifying solar superactive regions with vector magnetic field observations

The vector magnetic field characteristics of superactive regions (SARs) hold the key for understanding why SARs are extremely active and provide the guidance in space weather prediction. We aim to quantify the characteristics of SARs using the vector magnetograms taken by the Solar Magnetic Field Telescope at Huairou Solar Observatory Station. The vector magnetic field characteristics of 14 SARs in solar cycles 22 and 23 were analyzed using the following four parameters: 1) the magnetic flux imbalance between opposite polarities, 2) the total photospheric free magnetic energy, 3) the length of the magnetic neutral line with its steep horizontal magnetic gradient, and 4) the area with strong magnetic shear. Furthermore, we selected another eight large and inactive active regions (ARs), which are called fallow ARs (FARs), to compare them with the SARs. We found that most of the SARs have a net magnetic flux higher than 7.0\times10^21 Mx, a total photospheric free magnetic energy higher than 1.0\times10^24 erg/cm, a magnetic neutral line with a steep horizontal magnetic gradient (\geq 300 G/Mm) longer than 30 Mm, and an area with strong magnetic shear (shear angle \geq 80\degree) greater than 100 Mm^2. In contrast, the values of these parameters for the FARs are mostly very low. The Pearson \c{hi}2 test was used to examine the significance of the difference between the SARs and FARs, and the results indicate that these two types of ARs can be fairly distinguished by each of these parameters. The significance levels are 99.55%, 99.98%, 99.98%, and 99.96%, respectively. However, no single parameter can distinguish them perfectly. Therefore we propose a composite index based on these parameters, and find that the distinction between the two types of ARs is also significant with a significance level of 99.96%. These results are useful for a better physical understanding of the SAR and FARComment: 9 pages, 3 figures, 2 table

Reply to "Comment on 'Fano resonance for Anderson Impurity Systems' "

In a recent Comment, Kolf et al. (cond-mat/0503669) state that our analysis of the Fano resonance for Anderson impurity systems [Luo et al., Phys. Rev. Lett 92, 256602 (2004)] is incorrect. Here we want to point out that their comments are not based on firm physical results and their criticisms are unjustified and invalid.Comment: 1 page, 1 figure, to appear in PR