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[structure: see text] Apoptolidin (1) exhibits potent and highly selective apoptosis inducing activity against sensitive cancer cell lines and is hypothesized to act by inhibition of mitochondrial F(0)F(1)-ATP synthase. A series of apoptolidin derivatives, including a new intermolecular Diels-Alder adduct, were analyzed for antiproliferative activity in E1A-transformed rat fibroblasts. Potent F(0)F(1)-ATPase inhibition was not a sufficient determinant of antiproliferative activity for several analogues, suggesting the existence of a secondary biological target or more complex mode of action for apoptolidin. 相似文献
33.
We study the influence of lateral stress on the stability of thin viscoelastic films. The free surface of a deposited film under stress is shown to undergo an instability initiated by an anisotropic diffusion of the polymer molecules. This instability ultimately results in the formation of holes provided that the initial surface fluctuations are larger than a critical value. The latter is found to decrease when increasing the stress. An increase of the holes number density with the stress is therefore predicted. Most interestingly, the holes number density is also predicted to increase when increasing the molecular weight of the polymers. Additionally, we demonstrate that the friction of the substrate suppresses any spatial coherence between holes on large length scales. These predictions explain recent experimental observations made on thin spin-coated polystyrene films [G. Reiter, Nat. Mater. 4, 754 (2005)10.1038/nmat1484]. 相似文献
34.
Elie Nasr 《计算数学(英文版)》2010,(3):401-417
We present a new iterative reconstruction algorithm to improve the algebraic reconstruction technique (ART) for the Single-Photon Emission Computed Tomography. Our method is a generalization of the Kaczmarz iterative algorithm for solving linear systems of equations and introduces exact and implicit attenuation correction derived from the attenuated Radon transform operator at each step of the algorithm. The performances of the presented algorithm have been tested upon various numerical experiments in presence of both strongly non-uniform attenuation and incomplete measurements data. We also tested the ability of our algorithm to handle moderate noisy data. Simulation studies demonstrate that the proposed method has a significant improvement in the quality of reconstructed images over ART. Moreover, convergence speed was improved and stability was established, facing noisy data, once we incorporate filtration procedure in our algorithm. 相似文献
35.
This paper provides a simple approach for the consideration of quadratic BSDEs with bounded terminal conditions. Using solely probabilistic arguments, we retrieve the existence and uniqueness result derived via PDE-based methods by Kobylanski (2000) [14]. This approach is related to the study of quadratic BSDEs presented by Tevzadze (2008) [19]. Our argumentation, as in Tevzadze (2008) [19], highly relies on the theory of BMO martingales which was used for the first time for BSDEs by Hu et al. (2005) [12]. However, we avoid in our method any fixed point argument and use Malliavin calculus to overcome the difficulty. Our new scheme of proof allows also to extend the class of quadratic BSDEs, for which there exists a unique solution: we incorporate delayed quadratic BSDEs, whose driver depends on the recent past of the Y component of the solution. When the delay vanishes, we verify that the solution of a delayed quadratic BSDE converges to the solution of the corresponding classical non-delayed quadratic BSDE. 相似文献
36.
Christel Roux Wladimir Gorecki Jean-Yves Sanchez Elie Belorizky 《Macromolecular Symposia》1997,114(1):211-216
High molecular weight polymers have been prepared by ring-opening polymerization of propylene oxide PO using a Vandenberg initiator. Polymer electrolytes based on this polymer and an imide salt LiTFSI have been investigated. We present the results concerning the synthesis of the polymer and the glass transition temperatures evolution of the complexes with respect to salt composition. Diffusion constants of 19F and 7Li nuclei are determined by NMR techniques and a value of the cationic transport number t+ = 0.1 is obtained. 相似文献
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In an earlier paper Dartyge and Sárközy defined the measures of pseudo-randomness of subsets of {1,2,…,N}, and they presented several examples for subsets with strong pseudo-random properties. However, in applications one usually needs large families of subsets with strong pseudo-random properties. Here two constructions of this type are given. The notion of complexity of families of subsets of {1,…,N} is also introduced and studied. 相似文献
39.
In this paper, we investigate the time-varying interconnectedness of international Real Estate Investment Trusts (REITs) markets using daily REIT prices in twelve major REIT countries since the Global Financial Crisis. We construct dynamic total, net total and net pairwise return and volatility connectedness measures to better understand systemic risk and the transmission of shocks across REIT markets. Our findings show that that REIT market interdependence is dynamic and increases significantly during times of heightened uncertainty, including the COVID-19 pandemic. We also find that the US REIT market along with major European REITs are generally sources of shocks to Asian-Pacific REIT markets. Furthermore, US REITs appear to dominate European REITs. These findings highlight that portfolio diversification opportunities decline during times of market uncertainty. 相似文献
40.
Fabien?Closa Elie?Raph?el Alexei D.?ChepelianskiiEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(8):190
An ultra-strong photovoltaic effect has recently been reported for electrons trapped on a liquid helium surface under a microwave excitation tuned at intersubband resonance [D. Konstantinov, A.D. Chepelianskii, K. Kono, J. Phys. Soc. Jpn 81, 093601 (2012)]. In this article, we analyze theoretically the redistribution of the electron density induced by an overheating of the surface electrons under irradiation, and obtain quantitative predictions for the photocurrent dependence on the effective electron temperature and confinement voltages. We show that the photo-current can change sign as a function of the parameters of the electrostatic confinement potential on the surface, while the photocurrent measurements reported so far have been performed only at a fixed confinement potential. The experimental observation of this sign reversal could provide a reliable estimation of the electron effective temperature in this new out of equilibrium state. Finally, we have also considered the effect of the temperature on the outcome of capacitive transport measurement techniques. These investigations led us to develop, numerical and analytical methods for solving the Poisson-Boltzmann equation in the limit of very low temperatures which could be useful for other systems. 相似文献