The softwarization of wireless networks has necessitated an overhaul of existing mobility management strategies. Specifically, mobility management is no longer constrained to function within the boundaries of a pre-existing radio access network. Softwarization of the network infrastructure allows resource configurations and associations to be changed on-demand, in a manner so as to support a least cost mobility management framework. To this end, this paper presents an optimal radio access network design framework augmented with user-specific clusters from the perspective of mobility management. The proposed framework is supported by a detailed mathematical model that characterizes user mobility, system traffic, and signaling costs. Performance evaluation is based on a cost comparison with conventional LTE/NR networks, and reinforces the fact that the framework proposed herein results in significant cost reduction, even in the face of changing network scenarios.
A facile and flexible chemoenzymatic route for the preparation of a variety of amino acid-based surfactants ranging from simple
monoesters to more complex bola- and gemini-amphiphiles is described. The methodology is based on the observation that some
lipases, notably immobilized Candida antarctica and Rhizomucor miehei, readily accept N-Cbzamino acids as substrates and catalyze their esterification/amidation with long-chain alcohols and α,ω-diols/α,ω-diamines
in excellent yield. The resulting alkanediyl-α,ω-bis-(N-Cbz-amino acid) can be either deprotected using conventional procedures to attain a number of multifunctional bola-amphiphiles
or further modified to obtain a range of amino acid-based gemini surfactants. 相似文献
Altered mitochondrial function is currently recognized as an important factor in atherosclerosis initiation and progression. Mitochondrial dysfunction can be caused by mitochondrial DNA (mtDNA) mutations, which can be inherited or spontaneously acquired in various organs and tissues, having more or less profound effects depending on the tissue energy status. Arterial wall cells are among the most vulnerable to mitochondrial dysfunction due to their barrier and metabolic functions. In atherosclerosis, mitochondria cause alteration of cellular metabolism and respiration and are known to produce excessive amounts of reactive oxygen species (ROS) resulting in oxidative stress. These processes are involved in vascular disease and chronic inflammation associated with atherosclerosis. Currently, the list of known mtDNA mutations associated with human pathologies is growing, and many of the identified mtDNA variants are being tested as disease markers. Alleviation of oxidative stress and inflammation appears to be promising for atherosclerosis treatment. In this review, we discuss the role of mitochondrial dysfunction in atherosclerosis development, focusing on the key cell types of the arterial wall involved in the pathological processes. Accumulation of mtDNA mutations in isolated arterial wall cells, such as endothelial cells, may contribute to the development of local inflammatory process that helps explaining the focal distribution of atherosclerotic plaques on the arterial wall surface. We also discuss antioxidant and anti-inflammatory approaches that can potentially reduce the impact of mitochondrial dysfunction. 相似文献
The recently developed fast Fourier factorization method, which has greatly improved the application range of the differential theory of gratings, suffers from numerical instability when applied to metallic gratings with very low losses. This occurs when the real part of the refractive index is small, in particular, smaller than 0.1-0.2, for example, when silver and gold gratings are analyzed in the infrared region. This failure can be attributed to Li's "inverse rule" [L. Li, J. Opt. Soc. Am. A 13, 1870 (1996)] as shown by studying the condition number of matrices that have to be inverted. Two ways of overcoming the difficulty are explored: first, an additional truncation of the matrices containing the coefficients of the differential system, which reduces the numerical problems in some cases, and second, an introduction of lossier material inside the bulk, thus leaving only a thin layer of the highly conducting metal. If the layer is sufficiently thick, this does not change the optical properties of the system but significantly improves the convergence of the differential theory, including the rigorous coupled-wave method, for various types of grating profiles. 相似文献
Interface‐driven magnetic effects and phenomena associated with spin–orbit coupling and intrinsic symmetry breaking are of importance for fundamental physics and device applications. How interfaces affect the interplay between charge, spin, orbital, and lattice degrees of freedom is the key to boosting device performance. In LaMnO3/SrTiO3 (LMO/STO) polar–nonpolar heterostructures, electronic reconstruction leads to an antiferromagnetic to ferromagnetic transition, making them viable for spin filter applications. The interfacial electronic structure plays a critical role in the understanding of the microscopic origins of the observed magnetic phase transition, from antiferromagnetic at 5 unit cells (ucs) of LMO or below to ferromagnetic at 6 ucs or above, yet such a study is missing. Here, an atomic scale understanding of LMO/STO ambipolar ferromagnetism is offered by quantifying the interface charge distribution and performing first‐principles density functional theory (DFT) calculations across this abrupt magnetic transition. It is found that the electronic reconstruction is confined within the first 3 ucs of LMO from the interface, and more importantly, it is robust against oxygen nonstoichiometry. When restoring stoichiometry, an enhanced ferromagnetic insulating state in LMO films with a thickness as thin as 2 nm (5 uc) is achieved, making LMO readily applicable as barriers in spin filters. 相似文献