[en] We find that the U(N) two-instanton solution presented in [Phys. Lett. B 547 (2002) 85] is incorrect. For the U(2) case, we give a very simple form of the general two-instanton solution, so as to clearly show the faultiness of their solution. We also discuss the dilute instanton gas limit and the 't Hooft two-instanton based on our general solution

[en] The report has the historical character and represents the genesis of the standard model, estimation of its present situation and some remarks about the standard model future. The last has two version. If Einstein is right and the rock-bottom final truths of nature are accessible and attainable, then the standard model may be developed into a consistent fundamental theory or it will appear as a limiting case of some final theory. If Einstein's conviction turns out to be wrong then the standard model will appear to be one effective theory in an endless tower of effective theories

[en] In this Letter, a nonlinear recursive delayed feedback control strategy is proposed for stabilizing all the unknown fixed points of a chaotic discrete-time system. The proposed controller does not inherit the odd number limitation and relies on the system model only, i.e., the controller is independent of the information of the fixed points

[en] The electrorheology of electrorheological (ER) fluids based on zeolite and silicone oil under dc fields was investigated at room temperature. ER fluids with volume fractions of 27% and 30% were prepared and tested. When a 5 kV/mm dc field was applied, shear yield stress of 26.7 kPa was obtained for the latter. The ER fluid with a higher volume fraction of zeolite had a higher current density and a higher shear yield stress under the same electric field. Compared with other ER fluids based on zeolite particles with low shear yield stress, the zeolite employed by us was found to have high dielectric constant and conductivity. The high permittivity mismatch and the high conductivity mismatch of the components of the fluids were considered responsible for the high shear yield stress. [copyright] 2001 American Institute of Physics

[en] Melatonin may have antioxidant properties when it stimulates directly or indirectly antioxidant enzyme to activate and scavenge free radicals. So melatonin can reduce the radiation induced oxidative stress, DNA, chromosome and tissue injury. This paper presents a summary of radiation damage protection mechanism of melatonin, and radioprotective effects of radiation induced DNA, chromosome, and tissue damage, and puts forward the problems in the current study. (authors)

[en] The unobserved J^P = 0^- radial excitation D_s(2¹S₀) is anticipated to have mass 2650 MeV (denoted as D_s(2650)). Study of hadronic production is an important way to identify highly excited states. We study hadronic production of D_s(2650) from higher excited resonances in a ³P₀ model. Relevant hadronic partial decay widths are found to be very small, which implies it is difficult to observe D_s(2650) in hadronic decays of higher excited resonances. Hadronic decay widths of radially excited D_s(3P) have also been estimated. The total decay widths of four D_s(3P) are large, but the branching ratios in the D_s(2650)_η channel are very small, which implies that it seems impossible to observe D_s(2650) in hadronic decays of D_s(3P). The dominant decay channels of the four D_s(3P) have been pointed out, and D₁(2420), D₁(2430), D₂*(2460), D(2550), D(2600), (1¹D₂)D(2750) and D₃*(2760) are possible to observe in hadronic production from D_s(3P). (authors)

[en] It is proposed by Cvetic et al. [1] that the product of all horizon areas for general rotating multi-change black holes has universal expressions independent of the mass. When we consider the product of all horizon entropies, however, the mass will be present in some cases, while another new universal property [2] is preserved, which is more general and says that the sum of all horizon entropies depends only on the coupling constants of the theory and the topology of the black hole. The property has been studied in limited dimensions and the generalization in arbitrary dimensions is not straight-forward. In this Letter, we prove a useful formula, which makes it possible to investigate this conjectured universality in arbitrary dimensions for the maximally symmetric black holes in general Lovelock gravity and f(R) gravity. We also propose an approach to compute the entropy sum of general Kerr–(anti-)de-Sitter black holes in arbitrary dimensions. In all these cases, we prove that the entropy sum depends only on the coupling constants and the topology of the black hole

[en] Physicists are no strangers to Feynman diagrams, but the meaning of the diagrams is not always clear, even to those who have used them. That confusion has deep roots, as Kaiser clearly and convincingly explains. To Feynman himself, a diagram depicted an actual physical process in space-time, such as the exchange of photons that occurs when an electron and proton collide. However, he also saw it as shorthand for the contributions to the amplitude of a physical process made by the element of the process it depicted. The best part of this new book covers the early history, social history and 'conceptual history' of Feynman diagrams. Disagreements and criticisms aside, the book will be invaluable to historians and sociologists of physics interested in the growth of Feynman diagrams. (U.K.)

[en] The optimized dose and mechanism of low dose irradiation intensifying effect on cancer inhibition is investigated by using mice H₂₂ liver cancer model. The experimental result indicated that low dose irradiation has intensifying effect on cancer inhibition. The growth speed of planted tumors in the combined therapy groups significantly reduced (p < O.Ol) and the cancer cell death rate significantly increased (p < O.Ol) in comparison with in the chemical therapy. The synergism of low dose irradiation and cyclophosphamide killing cancer cells may probably be one of its mechanisms. Exposure to ⁶⁰Co γ rays at low doses may influence the Zn content of skin in mice bearing tumors to certain extent. Under this experiment condition, the optimized dose is l4 cGy at which irradiation had intensifying effect on cancer inhibition but less influence on the content of Zn in the skin. (authors)

[en] The rational design and appropriate use of the characteristic ligands is critical in the construction of the desired MOFs. Among various organic ligands, multidentate N- or O-donor ligands such as pyridine or pyrazine-carboxylic acids, have drawn extensive attention in the construction of coordination polymers owing to their versatile coordination modes and structural stability.7 For example, pyridine-2,6-, 2,5-, or 3,4-dicarboxylic and pyra-zile-2,3-dicarboxylic acids have been employed as successful multifunctional ligands, and a variety of MOFs with diverse topologies and interesting properties have been obtained. However, compared with other pyridine-dicarboxylic acids, pyridine-2,3-dicarboxylic acid (H₂PDA) is rarely employed as a linkage ligand