[en] In the paper, we study a super-conducting junctions device subject to an input periodic signal and a constant force. It is shown that, for this device, we can get current reversals for the current of the electron pairs versus the frequency of the periodic signal and negative conductance for the current of the electron pairs as a function of the constant force. (general)

[en] In this research, the comprehension levels and students difficulties on the subject of molecular geometry were determined via respondents ability test. This test consist of five items designed specifically to detect what the students think. One problem has several options, each of which has an indicator of learning difficulty so that when the student selects one of these options, the researcher can immediately detect the difficulties that the student has. The students answer comes with a reason to avoid guess answers. The test was applied on 52 students of grade X. Analysis of test results using descriptive qualitative analysis. According to the findings obtained from the test, the students had numerous difficulties. It was found there are 7 kinds difficulties in geometry molecules material. The top three difficulties experienced by students are (1) 71% of students do not understand the meaning of the symbol of lewis where students describe in the form of covalent bonds; (2) 65% of students do not understand the influence of free electron pairs at geometry molecules; 31% of students do not understand the various types of geometry molecules when given the problem of placing between the name and geometry of the molecules. These results shown that students still do not understand the basic concept of geometry molecules, so that it is required further investigation to find out how to overcome student learning difficulties on the topic of geometry molecules. (paper)

[en] Electron-pair excitations in the molecular hydrogen continuum are described by quantizing rotations of the momentum plane of the electron pair about by the pair's relative momentum. A helium-like description of the molecular pi.Joto double ionization is thus extended to higher angular momenta of the electron pair. A simple three-state superposition is found to account surprisingly well for recent observations of noncoplanar electron-pair, molecular-axis angular distributions.

[en] Considering the inclusive process, we study the doubly heavy baryon Ξ_cc (Ξ_bb) production through e⁺ e^- annihilation. Both the diquark QQ in color sextet and triplet are discussed. The results show that the contributions from these two color states play equally important roles. At the Z⁰ pole, a significant enhancement can be found in the doubly heavy baryon production. (authors)

[en] Short communication

[en] In this paper, having treated the t-J Hamiltonian in the mean-field approximation on basis generated by the Hubbard operators X^σ, the authors try to find the superconductive phase on the antiferromagnetic background. The pairing of the d-wave symmetry appeared to coexist well with the AF long-range order

[en] Interference of electromagnetic fields of the electron-positron pair constituents substantially influences interaction of pairs with matter. Suppression of ionization energy losses of electron-positron pairs in matter (the Chudakov effect) was predicted theoretically. Chudakov also suggested that the bremsstrahlung of an electron-positron pair can be suppressed owing to a similar interference mechanism. The aim of this paper is to investigate the influence of interference on the bremsstrahlung of high-energy electron-positron pairs. The author shows that interference leads to an increase in the yield of the bremsstrahlung of a pair rather than to its suppression. The predicted effect is investigated for the simplest case of motion of a pair in an amorphous medium. In this case, the energy ω of emitted photons is assumed to be small as compared to the energy of the pair constituents. This allows the author to consider the problem in the framework of classical electrodynamics

[en] Abstract only

[en] Short note. 1 ref

[en] The periodicity effect in the two centre Dirac problem is here analyzed from a physicist's point of view. The associated theoretical scenario is found able to explain all the existing major experimental findings and also to advance some new predictions. (author)