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Lyapunov exponent,Liao perturbation and persistence

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science China Mathematics 2020年第9期63卷 1913-1928页

作者： Wenxiang sun todd Young school of Mathematical sciences Peking UniversityBeijing 100871China Department of Mathematics Ohio UniversityAthensOH 45701USA

Consider a C1 vector eld together with an ergodic invariant probability that hasℓnonzero Lya-punov *** orthonormal moving frames along a generic orbit we construct a linear system ofℓdi erential equations which is a linearized Liao standard *** show that Lyapunov exponents of this linear system coincide with all the nonzero exponents of the given vector eld with respect to the given ergodic ***,we prove that these Lyapunov exponents have a persistence property meaning that a small perturbation to the linear system(Liao perturbation)preserves both the sign and the value of the nonzero Lyapunov exponents.

关键词： Lyapunov exponent Liao perturbation ergodic probability non-uniformly hyperbolicity

Kinetics of Molecular Recognition Mediated Nanoparticle self-Assembly

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Nano Research 2009年第1期2卷 78-84页

作者： Chinmay soman todd Giorgio Interdisciplinary Program in Materials science Vanderbilt University201 West End AvenueNashvilleTN 37240USA Department of Biomedical Engineering Vanderbilt University201 West End AvenueNashvilleTN 37240USA

Nanoscale quantum dot-antibody conjugates have been shown to self-assemble to form micron-scale aggregates in the presence of specific proteomic *** self-assembly process exhibits sigmoidal kinetics,sugges.ing that nucleation limits ***-assembly kinetics in this study is characterized by flow cytometric analysis of the aggregation reaction over time.A range of physiologically relevant concentrations of the protein angiopoietin-2,a candidate cancer biomarker,are incubated with quantum dots conjugated with a polyclonal mixture of anti-angiopoietin-2 *** concentration modulates the slopes and inflection times of the sigmoidal kinetics *** understanding of self-assembly kinetics in this system may lead to improvements in sensitivity and specificity of this novel proteomic biomarker detection technique and improve the screening,diagnostics,and therapy response monitoring for cancers and other *** approach to studying the kinetics of nanoparticle self-assembly may also provide a valuable tool for understanding the fundamental characteristics of nanoscale particle aggregation.

关键词： Quantum dot self-assembly kinetics proteomics diagnostics has

New Methodological Approach to Investigation of Kinetics of REE Extraction in Nonstationary Conditions

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Journal of Rare Earths 2007年第4期25卷 385-391页

作者： Kopyrin A A Fomichev A A Afonin M A todd T A saint-Petersburg Institute of Technology Idaho National Laboratory

The influence of periodical oscillations of the temperature on extraction and stripping processes in the extraction systems was studied. Two extraction systems were investigated：（1） 6 mol · L^-1 NaNO3-Nd（NO3）3-Pr（NO3）3-TBP kerosene and （2） [Nd（NO3）3 · 3TBP] -[ Pr（NO3）3 · 3TBP] -kerosene - 0.1 mol · L^-1 HNO3. Mathematical modeling of the nonstationary membrane extraction has been enhanced by including the dependence of the extraction rate constants on temperature. The values of activation energy for direct and reverse extraction and stripping reactions of Pr and Nd were calculated from experimental temporal dependencies of metal concentration and temperature by solving the reverse kinetics problem using the proposed mathematical model, A series of experiments with periodical oscillations of the temperature on the extraction system for the separation of rare earth elements （REE） using bulk liquid membrane between two extractors were performed. The mathematical model adequately describes the experimental data. The optimization of the extraction process for separation of REE by liquid membrane, under the influence of periodical oscillation of the temperature, was made based on the extraction rate constants and activation energies. The optimal conditions of separation by liquid membrane were found： frequency and amplitude of thermal oscillations, liquid membrane flow rate, and optimal ratio between organic and aqueous phase in extractors.

关键词： kinetics extraction non-stationary rare earths

Distribution of Primitive λ-Roots of Composite Moduli II

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Chinese Annals of Mathematics,series B 2006年第5期27卷 549-552页

作者： Zhiyong ZHENG todd COCHRANE Department of Mathematical sciences Tsinghua University Beijing 100084 China Department of Mathematics Kansas State University Manhattan Kansas 66506 USA.

We improve estimates for the distribution of primitive λ-roots of a composite modulus q yielding an asymptotic formula for the number of primitive A-roots in any interval I of length ｜I｜〉〉 q^1/2＋ε similar results are obtained for the distribution of ordered pairs （x, x^-1） with x a primitive λ-root, and for the number of primitive A-roots satisfying inequalities such as ｜x - x^-1｜≤ B.

关键词： λ-Roots Primitive roots

Upper bounds on a two-term exponential sum

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science China Mathematics 2001年第8期44卷 1003-1015页

作者： todd COCHRANE 郑志勇 Department of Mathematics Kansas State University Manhattan KS 66506 USA Department of Mathematics Tsinghua University Beijing 100084 China

We obtain upper bounds for mixed exponential sums of the type $s(\chi ,f,p^m ) = \sum\nolimits_{x = 1}^{p^n } {\chi (x)e} _{p^m } (ax^n + bx)$ where pm is a prime power with m? 2 and X is a multiplicative character (mod pm). If X is primitive or p?(a, b) then we obtain |s(χ,f,p m)| ?2np 2/3 m . If X is of conductor p and p?( a, b) then we get the stronger bound |s(χ,f,p m)|?np m/2.

关键词： exponential sums primitive character weil’sbound

Between Human and Animal： A study of New Year＇s sacrifice, Kong YijL and Diary of a Madman

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Frontiers of Literary studies in China-selected Publications from Chinese Universities 2012年第3期6卷 374-392页

作者： todd Foley Department of East Asian studies New York University New York NY 10003 USA

A subtle aspect of Lu Xun＇s writing, running through several of his works of fiction, is his animalistic portrayal of some of his most well-known characters. scraping away their humanity as he writes, Lu Xun depicts Kong Yiji, Xianglin sao, and the infamous Madman crawling on their hands and knees, working like draught animals, and abandoning all rational thought. In short, all three end up occupying an ambiguous space between the realms of human and animal. This paper attempts to examine how Lu Xun＇s description and situation of these characters suggests, aside from the standard agendas of May Fourth writing in general, a certain, shared metaphysical conundrum. Drawing on the work of Giorgio Agamben to take the hiatus between human and animal as an occasion for ontological possibility, I will investigate how the dehumanized portrayal of these characters situates them at the threshold of a new becoming： one which has not yet been realized, but which is also rendered impossible either through the character＇s death or return to health. Examining Lu Xun＇s works in this way not only recognizes his major emphasis on social critique, but suggests both that his thought on Chinese society pierces through to the level of metaphysical inquiry, and that the relationship between human and animal marks a productive entry point for this sort of questioning.

关键词： Lu Xun animality Agamben metaphysics Kong Yiji Xianglin sao Madman

A Breakthrough Performance： Being Human on Can Xue＇s Five spice street

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Frontiers of Literary studies in China-selected Publications from Chinese Universities 2016年第4期10卷 598-622页

作者： todd Foley Department of East Asian studies New York University New York NY 10003 USA

Of the many forms of literary experimentation that arose in China during the 198os, Can Xue＇s writing stands out as some of the strangest and most enigmatic. This article intends to examine her most significant work from that period, Five spice street （Wuxiang jie; first published under the title Breakthrough Performance [Tuwei biaoyan]）, in light of one of the major intellectual concerns in literature at the time： the question of the human. Through a close reading of the novel, I investigate the ways in which Can Xue interrogates and destabilizes the notion of the human with regard to the relationship between subject and object, corporeality, animality, sexuality, language, and time. Overall, I suggest that while Can Xue succeeds in offering a unique and provocative conceptualization of the human in Five spice street, she also refrains from ＂breaking through＂ the general realm of humanist discourse current at the time.

关键词： Can Xue Five spice street (Wuxiang jie) human physicality subjective reality

In-situ synthesis and sintering of mullite glass composites by sPs

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Journal of Advanced Ceramics 2014年第2期3卷 165-170页

作者： Jinyong ZHANG Hai ZHAN Zhengyi FU Richard todd state Key Laboratory of Advanced Technology for Materials synthesis and Proces.ing Wuhan University of TechnologyWuhan 430070China Department of Materials University of OxfordOxfordUK

The main subject of this work is an investigation of the effects of heating rate and current on the crystallisation of amorphous precursors in spark plasma sintering(sPs).For this,dry gel of Al_(2)O_(3)-siO_(2) with a molar ratio of 1:1,was synthesized and sintered in-situ by sPs,and also by hot pres.ing(HP)for *** analysis showed that the only crystalline product in both cases was mullite,whose Al_(2)O_(3) content was lower in the sPs *** microstructures showed a low volume fraction of large mullite fibers in the sPs specimens,whereas a high volume fraction of fine equiaxed grains was present in the HP *** main difference in microstructure between HP and sPs specimens could be explained in terms of the higher heating rate of the sPs *** size of the sPs die also affected the size and aspect ratio of the mullite fibers produced,which might have been due to either the different electrical current required or a difference in specimen temperature profile.

关键词： spark plasma sintering(sPs) synthesis extra-field mullite

Identification and characterization of new plant microRNAs using EsT analysis

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Cell Research 2005年第5期15卷 336-360页

作者： George P.COBB1,todd A.ANDERsON The Institute of Environmental and Human Health (TIEHH) and Department of Environmental Toxicology Texas Tech University Lubbock TX 79409-1163 UsA The Institute of Environmental and Human Health (TIEHH) and Department of Environmental Toxicology Texas Tech University Lubbock TX 79409-1163 UsA

seventy-five previously known plant microRNAs (miRNAs) were classified into 14 families according to their gene sequence identity. A total of 18,694 plant expressed sequence tags (EsT) were found in the GenBank EsT databases by comparing all previously known Arabidopsis miRNAs to GenBank’s plant EsT databases with BLAsT algorithms. After removing the EsT sequences with high numbers (more than 2) of mismatched nucleotides, a total of 812 EsT contigs were identified. After predicting and scoring the RNA secondary structure of the 812 EsT sequences using mFold software, 338 new potential miRNAs were identified in 60 plant species. miRNAs are widespread. some microRNAs may highly conserve in the plant kingdom, and they may have the same ancestor in very early evolution. There is no nucleotide substitution in most miRNAs among many plant species. some of the new identified potential miRNAs may be induced and regulated by environmental biotic and abiotic stresses. some may be preferentially expressed in specific tissues, and are regulated by developmental switching. These findings suggest that EsT analysis is a good alternative strategy for identifying new miRNA candidates, their targets, and other genes. A large number of miRNAs exist in different plant species and play important roles in plant developmental switching and plant responses to environmental abiotic and biotic stresses as well as signal transduction. Environmental stresses and developmental switching may be the signals for synthesis and regulation of miRNAs in plants. A model for miRNA induction and expression, and gene regulation by miRNA is hypothesized.

关键词： microRNA plant environmental stress gene regulation expressed sequence tags.