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1.
Anomalous x-ray pulsars (AXPs) and soft gamma-ray repeaters (SCRs) are believed to be candidates for magnetars, and they are powered by the decay of ultra-strong magnetic fields of〉 1014 C. From the modified spin-down relation of pulsars P ∝P^2-n, we find that the Vela pulsar would evolve into the classes of magnetars under some assumptions that pulsars lose their rotational energy only by magnetic dipole radiation and the braking index is a constant. Our rough calculation indicates that only pulsars with n - 1.3 - 1.6 can evolve into magnetars. Pulsars like Vela with a low braking index may be the progenitors of AXPs and SCRs. Regarding the mechanism evolved into magnetars, we suggest that pulsars' surface magnetic field component may be increased by frequent glitches. 相似文献
2.
<正>文[1]中有一道关于"得票高低"的初二竞赛试题(简称题[1]),其题目与解答如下:题目学生会选举有四个候选人A,B,C,D,已知D得票比B得票多,A、B得票之和超过C、D得票之和,A、C得票之和与B、D得票之和相等,则四人得票数由高到低的排列次序是().(A)A,D,C,B(B)D,B,A,C(C)D,A,B,C(D)A,D,B,C答:(D).解用圆形图表示,因A,C得票之和与B,D得票之和相等,作一直径分圆为两半,上部分B,D;下部为A,C;已知D得票比B得票多,画得扇形D大于扇形B;由A,B得票之和超过C,D得 相似文献
3.
We introduce polar substituents such as F, C1, Br into pentacene to enhance the dissolubility in common organic solvents while retaining the high charge-carrier mobilities of pentacene. Geometric structures, dipole moments, frontier molecule orbits, ionization potentials and electron affinities, as well as reorganization energies of those molecules, and of pentacene for comparison, are successively calculated by density functional theory. The results indicate that haiopentacenes have rather small reorganization energies (〈 0.2 eV), and when the substituents are in position 2 or positions 2 and 9, they are polarity molecules. Thus we conjecture that they can easily be dissolved in common organic solvents, and are promising candidates for organic semiconductors. 相似文献
4.
Recently, the mixing of scalar mesons was introduced into the chiral SU(3) quark model and also dynamically applied to the baryon-baryon system. The results show that the nucleon-nucleon and hyperon-nucleon scattering data can be reasonably described for different mixing cases, one is ideal mixing and the other is θs= 19° mixing. In the present work, by taking the above parameters, the possible candidate of deltaron bound state is further predicted. We find that the contributions from σ and ε exchange to binding energy of deltaron are different, that the contribution from ε exchange is negligible, and that σ exchange is dominant. We also find that the binding energy of deltaron is very stable, around several tens of MeV, no matter what kind of mixing is adopted. 相似文献
5.
In the conventional superconductors, the Cooper pairs are mediated by phonons, which is a process where only the correlations between the phonons and the charge properties of the electrons are needed. However, superconductivity can also be derived from other types of elementary excitations. The spin fluctuations are arguably the most promising candidate that can mediate such unconventional superconductivity. In some of the important systems such as cuprates, Fe-based superconductors and heavy-fermion superconductors, spin fluctuations play a key role in the mechanism of their superconductivity although there are still many debates. In this paper, we will give a brief review on the correlation between the spin fluctuations and superconductivity. 相似文献
6.
公开演讲对一个专业人员来说是必须的,但就像许多物理学家那样,你也许是个害羞的人,那你该怎样做呢?怎样才能做好你的报告,而不使你的专业受损或你的论文指导者丢脸呢?这里将给你一些建议。 相似文献
7.
By performing first-principles calculations, we study Li doping in a double-wall carbon nanotube where a (5,0) tube is confined inside a (14,0) tube. There are three possible sites for Li doping and two of them are energetically favorable. The change of energy band structure is closely related to the doping sites and the charge transfer is investigated. Bader charge analysis indicates that Li prefers to donate its electron to the inner (5,0) tube. Moreover, the Li capacity of the system can reach LIC4.75 which makes it a promising candidate for Li-ion battery materials. 相似文献
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The fixed target COMPASS experiment at CERN offers the opportunity to search for exotic mesons and glueball candidates in the light quark sector with unprecedented statistics.Preliminary results from the 2008 data taken with an incoming negative hadron beam (190 GeV/c,mainly pions) on a liquid hydrogen target are presented.New detectors dedicated to hadron beam measurements have been added.These give access to rare neutral and kaonic channels.An amplitude analysis which will allow to fit simultaneously diffractively and/or centrally produced resonances will be described and compared with those used in the CERN WA102 and BNL E852 experiments. 相似文献
10.
In the framework of the constituent quark model, the possible S-wave heavy dibaryon states with the c flavor are investigated. The factors which are responsible for the binding behavior of the dibaryon system are analyzed. It is shown that both the symmetry character of the system and the energy of interactions between interacting quarks are important for the binding behavior of the two-baryon system with the heavy flavor. As a result, seven possible candidates of heavy dibaryons with c flavor are predicted. 相似文献