[en] Possible topological invariant terms in the first quantization of strings associated with nonzero elements of the second cohomology group of space-time are investigated. The direct result of such terms is C-violation. (author)

[en] A solution of a pair of monopoles in 5d Kaluza-Klein theory without matter fields is given. The scale of the internal space is the same as that of the outer space. Its Euclidean version is useful for calculating the wave function of the universe with monopoles. (author)

[en] Using the first-principles theory, the band structures, electronic densities of states of Mn-doped, N-doped, and Mn-N co-doped SnO₂ systems were calculated. The results show that both single-doped and co-doped systems can reduce the band gap of SnO₂, and the densities of state in these doped systems move to the low energy region and more energy levels are introduced to the Fermi line, this will help the transition of electrons. comparing with the single-doped SnO₂, in the co-doped sample, there are the separations of energy levels at the tops of the valence band and conduction band, and more impurity energy levels are introduced in the band gap, the partial density of states of Mn is dispersed. Therefore, the co-doping makes Mn incorporation easier. (authors)

[en] We argue that the large-N strong/weak phase transition is a generic phenomenon in a finite temperature supersymmetric Yang-Mills theory of maximal supersymmetry. N = 4, D = 4 SYM is the canonical example, where we also argue that the large-N Hawking-Page phase transition disappears for a sufficiently small coupling. The Hawking-Page transition temperature is lowered by the first α' correction. Physically, the strong/weak phase transition is identified with the correspondence point of Horowitz and Polchinski. We also try to construct toy models to demonstrate the large-N phase transitions, with limited success

[en] Based on a gas picture of D0-brane partons, it is shown that the entropy, as well as the geometric size of an infinitely boosted Schwarzschild black hole, can be accounted for in matrix theory by interactions involving spins, or interactions involving more than two bodies simultaneously. (author)

[en] It is shown that a pair of vortex and anti-vortex is completely screened in 2+1 dimensional Yang-Mills theory and 3+1 dimensional Yang-Mills theory in the strong coupling limit, based on the recent conjecture of Maldacena. This is consistent with the fact that these theories exhibit confinement. (author)

[en] The point where a D2-brane intersecting a stack of D2-branes is proposed as a candidate for the 't Hooft vortex in the world-volume theory of N D2-branes. This straightforwardly generalizes to D3-branes, where a vortex line is generated by the intersection. Similarly, there are such objects on M-branes. We use Maldacena's conjecture to compute the static potential between a vortex and an anti-vortex in each case, in the large N limit. (author)

[en] The AdS/CFT correspondence provides valuable constraints on the possible exact form of various physical quantities in the N=4 super Yang-Mills theory in the large N limit. We examine the free energy as the expansions in a small as well as in a large 't Hooft parameter λ. We argue that it is impossible to smoothly extrapolate from the weak coupling regime to the strong coupling regime, thus there must exist a large N phase transition in λ at a finite temperature. We also argue that there is no world-sheet instanton in the background of the Euclidean anti-de Sitter black hole. (author)

[en] The purpose of the auxiliary steam supply system is to provide auxiliary steam for users when the main steam is not available. This paper develops a targeted optimization solution through analyzing the influence factors of internal corrosion rate during the operation of the auxiliary boiler. Wet maintenance is carried out by using hydrazine and ammonia water mixture during the shutdown of auxiliary boiler, without changing the existing structure and equipment of the auxiliary boiler. In addition, an appropriate amount of hydrazine is added to the feed water of the auxiliary boiler during the operation of the auxiliary boiler, so as to effectively reduce the content of corrosion products in the water of the auxiliary boiler during its operation, and guarantee the safe operation of the auxiliary boiler. (authors)

[en] We derive the modular transformations for conformal blocks in Wess-Zumino-Witten models on Riemann surfaces of higher genus. The basic ingredient consists of using the Chern-Simons theory developed by Witten. We find that the modular transformations generated by Dehn twists are linear combinations of Wilson line operators, which can be expressed in terms of braiding matrices. It can also be shown that modular transformation matrices for g > 0 Riemann surfaces depend only on those for g ≤ 3. (author). 13 refs, 15 figs