Magnetic field as a means to identify initiating reaction in oxidation of organic substances with molecular oxygen

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Facile synthesis of temperature-sensitive ABA triblock copolymers by dispersion RAFT polymerization

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基于故事情景链语法的偶动画短片分析与建模

偶动画是动画领域一个重要的分支，与传统手绘动画同步出现，甚至更早。偶动画作品以其独特的拍摄方法和艺术魅力，为众多艺术家和观众所喜爱。偶动画影片设计周期长、工作量大、生产过程复杂、经济风险高，用传统手工工艺制作完成一部5 min的定格动画影片，通常需要数年。本文以丹麦知名动画导演克里多夫·皮拉丹的《柏树山上的风》及德国格里高利·祖坎导演的《龙焰火枪》为例，提出以故事情节(storyline(i)),?i∈1,2,…,n?与情景链（scenario?chain）语法有限集的形式语言表达式分解偶动画电影的故事元素，通过叙事空间（narrative?space）中镜头画面的组接逻辑，形成不同叙事结构，以分析定格动画电影的故事寓意（implied?meaning），从故事计算的角度将其转化为标准化设计流程，为构建偶动画电影故事建模理论以及辅助智能计算提供思路，方法提高了偶动画电影的设计与制作效率，为多学科协同创作提供了新模式，使普通偶动画爱好者也能参与创作。     

The Polymer Physics of Multiscale Charge Transport in Conjugated Systems

Conjugated polymers are promising candidates for next‐generation low‐cost flexible electronics. Field‐effect transistors comprising conjugated polymers have witnessed significant improvements in device performance, notably the field‐effect mobility, in the last three decades. However, to truly make these materials commercially competitive, a better understanding of charge‐transport mechanisms in these structurally heterogeneous systems is needed for providing systematic guides for further improvements. This review assesses the key microstructural features of conjugated polymers across multiple length scales that can influence charge transport, with special attention given to the underlying polymer physics. The mechanistic understanding from collective experimental and theoretical studies point to the importance of interconnected ordered domains given the macromolecular nature of the polymeric semiconductors. Based on the criterion, optimization to improve charge transport can be broadly characterized by efforts to (a) promote intrachain transport, (b) establish intercrystallite connectivity, and (c) enhance interchain coupling. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1559–1571     

Mixing time of an unaligned Gibbs sampler on the square

The paper concerns a particular example of the Gibbs sampler and its mixing efficiency. Coordinates of a point are rerandomized in the unit square ${[0,1]}^2$ to approach a stationary distribution with density proportional to $exp(?A^2{(u?v)}^2)$ for $(u,v)\in {[0,1]}^2$ with some large parameter $A$.Diaconis conjectured the mixing time of this process to be $O\left(A^2\right)$ which we confirm in this paper. This improves on the currently known $O(exp\left(A^2\right))$ estimate.     

Continuum versus discrete networks,graph Laplacians,and reproducing kernel Hilbert spaces

Motivated by applications to machine learning, we construct a reversible and irreducible Markov chain whose state space is a certain collection of measurable sets of a chosen l.c.h. space $\mathfrak{X}$. We study the resulting network (connected undirected graph), including transience, Royden and Riesz decompositions, and kernel factorization. We describe a construction for Hilbert spaces of signed measures which comes equipped with a new notion of reproducing kernels and there is a unique solution to a regularized optimization problem involving the approximation of $L^2$ functions by functions of finite energy. The latter has applications to machine learning (for Markov random fields, for example).     

The survival probability of critical and subcritical branching processes in finite state space Markovian environment

Let ${\left(Z_n\right)}_{n\ge 0}$ be a branching process in a random environment defined by a Markov chain ${\left(X_n\right)}_{n\ge 0}$ with values in a finite state space $\mathbb{X}$. Let ${\mathbb{P}}_i$ be the probability law generated by the trajectories of ${\left(X_n\right)}_{n\ge 0}$ starting at $X_0=i\in \mathbb{X}.$ We study the asymptotic behaviour of the joint survival probability ${\mathbb{P}}_i\left(Z_n>0,X_n=j\right)$, $j\in \mathbb{X}$ as $n\to +\infty$ in the critical and strongly, intermediate and weakly subcritical cases.     

Persistence of sums of correlated increments and clustering in cellular automata

Let $T$ be the first return time to $(?\infty ,0]$ of sums of increments given by a functional of a stationary Markov chain. We determine the asymptotic behavior of the survival probability, $\mathbb{P}(T\ge t)～C{t}^{?1∕2}$ for an explicit constant $C$. Our analysis is based on a connection between the survival probability and the running maximum of the time-reversed process, and relies on a functional central limit theorem for Markov chains. As applications, we recover known clustering results for the 3-color cyclic cellular automaton and the Greenberg–Hastings model, and we prove a new clustering result for the 3-color firefly cellular automaton.     

Cationic para‐phenyl‐substituted α‐diimine nickel catalyzed ethylene and 4‐methyl‐1‐pentene (co)polymerizations via living/controlled chain‐walking

Upon activation with diethylaluminium chloride (Et₂AlCl), a series of phenyl‐substituted α‐diimine nickel precatalysts conducted 4‐methyl‐1‐pentene (4MP) and ethylene (E) (co)polymerizations via controlled chain‐walking to generate branched amorphous polymers with high molecular weight and narrow molecular weight distribution (M_w/M_n < 1.6). The obtained poly(4MP)s were amorphous elastomers with glass transition temperature (T_g) of ?10 ~ ?24 °C, which are higher than that of E‐4MP copolymer ( ? 63.0 °C). At room temperature (25 °C), 4MP polymerization proceeds in a living manner. The microstructures of the produced poly(4MP)s indicated the 2,1‐ and 1,2‐insertion followed by chain‐walking, the latter being predominant. The NMR analyses of the polymers showed that the obtained poly(4MP) possessed methyl, isobutyl, 2,4‐dimethylpentyl and 2‐methylhexyl groups, while the isobutyl and 2,4‐dimethylalkyl branches derived from 4MP were observed in the E‐4MP copolymer. The branch structures and the insertion‐type of monomer were depended on the polymerization temperature, and the content of methyl branch increased with an increase in the polymerization temperature.