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921.
We consider finite groups G for which any two cyclic subgroups of the same order are conjugate in G. We prove various structure results and, in particular, that any such group has at most one non-abelian composition factor, and this is isomorphic to PSL(2, p m ), with m odd if p is odd, or to Sz(22m+1), or to one of the sporadic groups M 11, M 23, or J 1. 相似文献
922.
Ovidiu Savin Enrico Valdinoci 《Calculus of Variations and Partial Differential Equations》2013,48(1-2):33-39
We show that the only nonlocal s-minimal cones in ${\mathbb{R}^2}$ are the trivial ones for all ${s \in (0, 1).}$ As a consequence we obtain that the singular set of a nonlocal minimal surface has at most n ? 3 Hausdorff dimension. 相似文献
923.
Philippe Boutinaud Piotr Putaj Rachid Mahiou Enrico Cavalli Adolfo Speghini 《光谱学快报》2013,46(2):209-220
The quenching of the luminescence originating from the excited states 3P0 and 1D2 of Pr3+ and 5D3 and 5D4 of Tb3+ has been studied in oxide crystals containing closed shell transition metal ions, such as titanates, vanadates, niobates, and tantalates. It has been shown that the emission from these excited states can be quenched by an intervalence charge transfer mechanism. The temperature dependence of the emission intensities has allowed estimating indicative activation energies for the crossover to the intervalence charge transfer state. In the case of Tb3+, the quenching gives rise to relatively short decay times for the 5D4 state. 相似文献
924.
In this paper we study noise-induced bimodality in a specific circuit with many biological implications, namely a single-step enzymatic cycle described by Michaelis–Menten equations. We study the biological feasibility of this phenomenon, which allows for switch-like behavior in response to graded stimuli, considering a small and discrete number of molecules involved in the circuit, and we characterize the conditions necessary for it. We show that intrinsic noise (due to the stochastic character of the Master Equation approach) of a one-dimensional substrate reaction is not sufficient to achieve bimodality, then we characterize analytically the necessary conditions on enzyme number fluctuations. We implement numerically two model circuits that show bimodality over different parameter windows, that depend critically on system size as predicted by our results, providing hints about how such a phenomenon could be exploited in real biological systems. 相似文献
925.
926.
Yik-Hoi Au-Yeung 《Linear and Multilinear Algebra》2013,61(1-4):93-100
Let A be a bounded linear operator in a quaternionic Hilberi space (H,(·,·)). The numerical range of A is defined to be the set W (A)={( Au, u): u ε H, (u,u) = 1}. Quite different from the complex caseW (A) may not be convex. In this note the author proves that W (A) is convex if and only if R ∩ W (A) = {Req : q ε W(A)}. where R is the real field and Re q denotes the real part of the quaternion q. For a normal operator A in a finite dimensional space H, the author gives a characterization on the convexity of W(A) in terms of ihe eigenvalues of A and also proves that the generalized numerical range of A is convex if and only if A is Hermitian. 相似文献
927.
Stefania Balzan Barbara Cardazzo Enrico Novelli Lisa Carraro Federico Fontana Sarah Curr Matteo Laghetto Angela Trocino Gerolamo Xiccato Agnese Taticchi Luca Fasolato 《Molecules (Basel, Switzerland)》2021,26(14)
Olive vegetation water (OVW) is a by-product with a noticeable environmental impact; however, its polyphenols may be reused food and feed manufacture as high-value ingredients with antioxidant/antimicrobial activities. The effect of dietary supplementation with OVW polyphenols on the gut microbiota, carcass and breast quality, shelf life, and lipid oxidation in broiler chickens has been studied. Chicks were fed diets supplemented with crude phenolic concentrate (CPC) obtained from OVW (220 and 440 mg/kg phenols equivalent) until reaching commercial size. Cloacal microbial community (rRNA16S sequencing) was monitored during the growth period. Breasts were submitted to culture-dependent and -independent microbiological analyses during their shelf-life. Composition, fatty acid concentration, and lipid oxidation of raw and cooked thawed breasts were measured. Growth performance and gut microbiota were only slightly affected by the dietary treatments, while animal age influenced the cloacal microbiota. The supplementation was found to reduce the shelf life of breasts due to the growth of spoilers. Chemical composition and lipid oxidation were not affected. The hydroxytyrosol (HT) concentration varied from 178.6 to 292.4 ug/kg in breast muscle at the beginning of the shelf-life period. The identification of HT in meat demonstrates that the absorption and metabolism of these compounds was occurring efficiently in the chickens. 相似文献
928.
Roberto Fallica Enrico Varesi Luca Fumagalli Simona Spadoni Massimo Longo Claudia Wiemer 《固体物理学:研究快报》2013,7(12):1107-1111
The 3ω method was employed to determine the effect of nitrogen doping (5 at.%) on the thermal conductivity of sputtered thin films of stoichiometric GeTe (a material of interest for phase change memories). It was found that nitrogen doping has a detrimental effect on the thermal conductivity of GeTe in both phases, but less markedly in the amorphous (–25%) than in the crystalline one (–40%). On the opposite, no effect could be detected on the measured thermal boundary resistance between these films and SiO2, within the experimental error. Our results agree with those obtained by molecular dynamic simulation of amorphous GeTe. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
929.
A Bazzani GC Castellani E Giampieri D Remondini LN Cooper 《The Journal of chemical physics》2012,136(23):235102
Dual phospho/dephosphorylation cycles, as well as covalent enzymatic-catalyzed modifications of substrates are widely diffused within cellular systems and are crucial for the control of complex responses such as learning, memory, and cellular fate determination. Despite the large body of deterministic studies and the increasing work aimed at elucidating the effect of noise in such systems, some aspects remain unclear. Here we study the stationary distribution provided by the two-dimensional chemical master equation for a well-known model of a two step phospho/dephosphorylation cycle using the quasi-steady state approximation of enzymatic kinetics. Our aim is to analyze the role of fluctuations and the molecules distribution properties in the transition to a bistable regime. When detailed balance conditions are satisfied it is possible to compute equilibrium distributions in a closed and explicit form. When detailed balance is not satisfied, the stationary non-equilibrium state is strongly influenced by the chemical fluxes. In the last case, we show how the external field derived from the generation and recombination transition rates, can be decomposed by the Helmholtz theorem, into a conservative and a rotational (irreversible) part. Moreover, this decomposition allows to compute the stationary distribution via a perturbative approach. For a finite number of molecules there exists diffusion dynamics in a macroscopic region of the state space where a relevant transition rate between the two critical points is observed. Further, the stationary distribution function can be approximated by the solution of a Fokker-Planck equation. We illustrate the theoretical results using several numerical simulations. 相似文献
930.
A method for five- and six-membered heterocycle formation by palladium-catalyzed C-H/N-H coupling is presented. The method employs a picolinamide directing group, PhI(OAc)(2) oxidant, and toluene solvent at 80-120 °C. Cyclization is effective for sp(2) as well as aliphatic and benzylic sp(3) C-H bonds. 相似文献