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971.
Inversion symmetry is a very non-trivial discrete symmetry of Frobenius manifolds. It was obtained by Dubrovin from one of the elementary Schlesinger transformations of a special ODE associated to a Frobenius manifold. In this paper, we review the Givental group action on Frobenius manifolds in terms of Feynman graphs and obtain an interpretation of the inversion symmetry in terms of the action of the Givental group. We also consider the implication of this interpretation of the inversion symmetry for the Schlesinger transformations and for the Hamiltonians of the associated principle hierarchy. 相似文献
972.
The dependence on voltage of the correlation length of turbulence in the dynamic scattering mode in an ac excited nematic liquid crystal has been measured and discussed. The influence of a high frequency stabilizing field has been shown. The total anisotropy of the turbulent medium has been demonstrated, using measurements on a wedge-shaped sample. 相似文献
973.
Petr Slaný Miroslava Pokorná Zdeněk Stuchlík 《General Relativity and Gravitation》2013,45(12):2611-2633
Equatorial circular orbits of test particles in the Kerr–anti-de Sitter black-hole and naked-singularity spacetimes are analyzed and their properties like the existence, orientation and stability are discussed. Due to the attractive cosmological constant ( $\varLambda <0$ ), all particles moving along equatorial orbits are still bound in the gravitational field of the central object. In general, there are two families of equatorial circular orbits. Particles moving along minus-family orbits possess negative angular momentum and, thus, they are counterrotating from the point of view of the locally non-rotating frames (LNRF). Particles moving along plus-family orbits possess, in most cases, positive angular momentum and belong to corotating particles from the point of view of the LNRF. Nevertheless, in stationary regions inside black holes and also near naked singularities with appropriately chosen value of the cosmological constant and rotational parameter $a<1.299$ , there are also counterrotating plus-family circular orbits. Moreover, in spacetimes with $a<1.089$ , some of these orbits are characterized by negative specific energy, indicating the bounding energy of the particle, moving along such an orbit, higher than its rest energy. In black-hole spacetimes, all such orbits are radially unstable, but in naked-singularity spacetimes, stable counterrotating orbits with negative specific energy exist. 相似文献
974.
Currently there are two proposed ansätze for NSR superstring measures: the Grushevsky ansatz and the OPSMY ansatz, which for genera g?4 are known to coincide. However, neither the Grushevsky nor the OPSMY ansatz leads to a vanishing two-point function in genus four, which can be constructed from the genus five expressions for the respective ansätze. This is inconsistent with the known properties of superstring amplitudes. 相似文献
975.
Wojciech Krzemien Monika Rohlickova Miloslav Machacek Veronika Novakova Jaroslaw Piskorz Petr Zimcik 《Molecules (Basel, Switzerland)》2021,26(14)
The photodynamic properties of a series of non-halogenated, dibrominated and diiodinated BODIPYs with a phthalimido or amino end modification on the phenoxypentyl and phenoxyoctyl linker in the meso position were investigated. Halogen substitution substantially increased the singlet oxygen production based on the heavy atom effect. This increase was accompanied by a higher photodynamic activity against skin melanoma cancer cells SK-MEL-28, with the best compound reaching an EC50 = 0.052 ± 0.01 µM upon light activation. The dark toxicity (toxicity without light activation) of all studied dyes was not detected up to the solubility limit in cell culture medium (10 µM). All studied BODIPY derivatives were predominantly found in adiposomes (lipid droplets) with further lower signals colocalized in either endolysosomal vesicles or the endoplasmic reticulum. A detailed investigation of cell death indicated that the compounds act primarily through the induction of apoptosis. In conclusion, halogenation in the 2,6 position of BODIPY dyes is crucial for the efficient photodynamic activity of these photosensitizers. 相似文献
976.
We investigate the so-called critical 2nth-order Sturm–Liouville difference operators and associated symmetric banded matrices. We show that arbitrarily small (in a certain sense) negative perturbation of a non-negative critical operator leads to an operator which is no longer non-negative. 相似文献
977.
Roman Šimon Hilscher Petr Zemánek 《Journal of Difference Equations and Applications》2013,19(1):84-117
In this paper we develop the Weyl–Titchmarsh theory for discrete symplectic systems with general linear dependence on the spectral parameter. We generalize and complete several recent results concerning these systems, which have the spectral parameter only in the second equation. Our new theory includes characterizations of the Weyl discs and Weyl circles, their limiting behaviour, properties of square summable solutions including the analysis of the exact number of linearly independent square summable solutions and limit point/circle criteria. Some illustrative examples are also provided. 相似文献
978.
979.
Khlyabich PP Burkhart B Thompson BC 《Journal of the American Chemical Society》2012,134(22):9074-9077
Ternary blend bulk heterojunction (BHJ) solar cells containing as donor polymers two P3HT analogues, high-band-gap poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) (P3HT(75)-co-EHT(25)) and low-band-gap poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP-10%), with phenyl-C(61)-butyric acid methyl ester (PC(61)BM) as an acceptor were studied. When the ratio of the three components was varied, the open-circuit voltage (V(oc)) increased as the amount of P3HT(75)-co-EHT(25) increased. The dependence of V(oc) on the polymer composition for the ternary blend regime was linear when the overall polymer:fullerene ratio was optimized for each polymer:polymer ratio. Also, the short-circuit current densities (J(sc)) for the ternary blends were bettter than those of the binary blends because of complementary polymer absorption, as verified using external quantum efficiency measurements. High fill factors (FF) (>0.59) were achieved in all cases and are attributed to high charge-carrier mobilities in the ternary blends. As a result of the intermediate V(oc), increased J(sc) and high FF, the ternary blend BHJ solar cells showed power conversion efficiencies of up to 5.51%, exceeding those of the corresponding binary blends (3.16 and 5.07%). Importantly, this work shows that upon optimization of the overall polymer:fullerene ratio at each polymer:polymer ratio, high FF, regular variations in V(oc), and enhanced J(sc) are possible throughout the ternary blend composition regime. This adds to the growing evidence that the use of ternary blends is a general and effective strategy for producing efficient organic photovoltaics manufactured in a single active-layer processing step. 相似文献
980.
Ali AHMAD Kashif ALI Martin BAA Petr KOVR Andrea SEMANIOV-FENOVíKOV 《数学学报(英文版)》2012,28(9):1865-1874
Let G = (V, E) be a finite, simple and undirected graph with p vertices and q edges. An (a, d)-vertex-antimagic total labeling of G is a bijection f from V (G) ∪ E(G) onto the set of consecutive integers 1, 2, . . . , p + q, such that the vertex-weights form an arithmetic progression with the initial term a and difference d, where the vertex-weight of x is the sum of the value f (x) assigned to the vertex x together with all values f (xy) assigned to edges xy incident to x. Such labeling is called super if the smallest possible labels appear on the vertices. In this paper, we study the properties of such labelings and examine their existence for 2r-regular graphs when the difference d is 0, 1, . . . , r + 1. 相似文献