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111.
The small-world phenomenon is one of the most important properties found in social networks. It includes both short path lengths and efficient navigation between two individuals. It is found by Kleinberg that navigation is efficient only if the probability density distribution of an individual to have a friend at distance r scales as P(r) ~ r(-1). Although this spatial scaling is found in many empirical studies, the origin of how this scaling emerges is still missing. In this Letter, we propose the origin of this scaling law using the concept of entropy from statistical physics and show that this scaling is the result of optimization of collecting information in social networks. 相似文献
112.
Valentin Garbe Barbara Abendroth Hartmut Stcker Arkadi Gavrilov Doron Cohen‐Elias Shlomo Mehari Dan Ritter Dirk C. Meyer 《Crystal Research and Technology》2015,50(6):425-431
Commercially available hydride vapor phase epitaxy gallium nitride (GaN) is characterized with the aim to correlate the oxygen and hydrogen secondary ion mass spectrometry profiles of a GaN wafer with the electrical properties of the sample. A GaN layer model, including doping profile and mobility, is derived, utilizing electrical (capacitance–voltage, Hall), structural (high resolution X‐ray diffraction) and optical (polarized infrared spectroscopy) methods. Oxygen and hydrogen are easily incorporated during hydride vapor phase epitaxy growth of GaN. Oxygen is an n‐type dopant in GaN, whereas hydrogen may passivate some of the donors. Electrical and optical properties correlate with a low defect concentration top GaN layer and a high defect concentration GaN interlayer. 相似文献
113.
Shlomo Bekhor Moshe E. Ben-Akiva M. Scott Ramming 《Annals of Operations Research》2006,144(1):235-247
This paper discusses choice set generation and route choice model estimation for large-scale urban networks. Evaluating the
effectiveness of Advanced Traveler Information Systems (ATIS) requires accurate models of how drivers choose routes based
on their awareness of the roadway network and their perceptions of travel time. Many of the route choice models presented
in the literature pay little attention to empirical estimation and validation procedures. In this paper, a route choice data
set collected in Boston is described and the ability of several different route generation algorithms to produce paths similar
to those observed in the survey is analyzed. The paper also presents estimation results of some route choice models recently
developed using the data set collected. 相似文献
114.
115.
The convergence of stochastic processes indexed by parameters which are elements of a metric space is investigated in the context of an invariance principle of the uniform central limit theorem (UCLT) for stationary Markov chains. We assume the integrability condition on metric entropy with bracketing. An eventual uniform equicontinuity result is developed which essentially gives the invariance principle of the UCLT. We translate the problem into that of a martingale difference sequence as in Gordin and Lifsic.(7) Then we use the chaining argument with stratification adapted from that of Ossiander.(11) The results of this paper generalize those of Levental(10) and Ossiander.(11) 相似文献
116.
117.
Fluorine acts as an electrophile and, as such, reacts with remote and unactivated tertiary hydrogens in aliphatic alcohols and acids, resulting in the corresponding fluorine derivatives. 相似文献
118.
We show that a hopping model may explain the experimental temperature dependence of the electron mobility in molecular crystals. The flat, higher temperature portion is obtained if anharmonic effects are included in a simple manner. The low temperature part is obtained if coherent effects are added to the diffusional ones. 相似文献
119.
Sufficient conditions are derived for the continuous dependence of C
1-solutions of the mixed boundary value problem (with dead loading) upon the given data, within the framework of nonlinear hyperelasticity.The second author was a visitor at the Department of Mathematics, University of Strathclyde, Glasgow, Scotland, at the time that the revised version was prepared. Author's present address: Department of Mathematics, Plymouth Polytechnic, Plymouth, England. 相似文献
120.
Alexander Kamyshny Daria Trofimova Shlomo Magdassi Andrey Levashov 《Colloids and surfaces. B, Biointerfaces》2002,24(3-4):177-183
The enzymatic activity of the native and modified glucose oxidase (GOx) from Aspergillus niger in the system of reversed micelles of Aerosol OT in octane was investigated. Two forms of the modified enzyme were studied: a hydrophobized form obtained by the attachment of palmitic chains to lysine amino groups by the reaction with palmitic acid ester of N-hydroxysuccinimide and a glycosylated (hydrophilized) form obtained by the attachment of the cellobiose moieties. The native glucose oxidase and its derivatives, while incorporated into micelles in a surfactant concentration range from 0.05 to 0.3 M, display an enzymatic activity, which is comparable with the activity in aqueous solution. The dependence of the enzymatic activity on hydration degree of surfactant (the molar ratio of water to surfactant, W0) does not indicate the formation of qualitatively new associated forms of the enzyme subunits inside the micelles. The apparent size of Aerosol OT micelles obtained by dynamic light scattering gradually increases from 10±3 nm at low W0 up to 25±5 nm at high W0. Incorporation of the native and hydrophobized glucose oxidase into micelles does not affect their mean size. Kinetic analysis shows that the enzyme specificity is about an order of magnitude greater in the system of reversed micelles as compared with aqueous solution. 相似文献