Tumor Biochemical Heterogeneity and Cancer Radiochemotherapy: Network Breakdown Zone-Model

Breakdowns of two-zone random networks of the Erdős–Rényi type are investigated. They are used as mathematical models for understanding the incompleteness of the tumor network breakdown under radiochemotherapy, an incompleteness that may result from a tumor’s physical and/or chemical heterogeneity. Mathematically, having a reduced node removal probability in the network’s inner zone hampers the network’s breakdown. The latter is described quantitatively as a function of reduction in the inner zone’s removal probability, where the network breakdown is described in terms of the largest remaining clusters and their size distributions. The effects on the efficacy of radiochemotherapy due to the tumor micro-environment (TME)’s chemical make-up, and its heterogeneity, are discussed, with the goal of using such TME chemical heterogeneity imaging to inform precision oncology.     

评估政策感知对居民绿色出行意向的影响

绿色出行的引导效果受政策及出行者选择偏好影响,需要考虑不同类型的低碳引导政策和出行者的异质性。为定量分析政策和出行者异质性对出行行为的影响,将政策分为三种：经济、便利和公共信息政策感知,基于521份绿色出行问卷调查数据,采用K-means聚类将出行者划分为享乐型组(60.7%)和实用型组(39.3%)。偏最小二乘法结构方程模型(partial least square method of structural equation model, PLS-SEM)的结果表明：在出行者绿色出行行为中,若不考虑出行者的异质性,可能高估或低估政策对出行者绿色出行意向的影响;享乐型组的绿色出行意向受公共信息政策感知的影响大于实用型组,受经济政策感知的影响小于实用型组;公共信息政策是引导享乐型组和实用型组绿色出行最重要的政策措施。     

消费者需求异质性与企业竞争优势异质性关系

从计量经济学的角度,运用技术替代、规模经济、学习经济,以及关于消费者对产品性能边际效用递减和产品性能对生产成本的边际效用随时间递减的规律,对企业异质性竞争优势和消费者异质性需求的动态关系进行分析.结果表明:异质性消费者需求为企业异质性竞争优势提供了市场环境和存在的理由,具有异质性竞争优势的企业为消费者的异质性需求提供了选择的可能性和价值;特定企业只有建立适合于特定消费者的不断变化的异质性需求的异质性竞争优势,才能在竞争中获得持续发展.     

脆性材料破坏过程分析的数值试验方法

文中运用作者新近开发的材料破坏过程分析MFPA2D系统,以岩石、混凝土等非均匀脆性材料的破坏过程分析为例,说明了数值模拟方法给脆性材料破坏理论发展所带来的契机,并简述了MFPA2D在煤层移动、地下工程稳定性、地震孕育机制,以及复合材料破坏问题研究中的应用前景．     

不同围压作用下非均匀岩石水压致裂过程的数值模拟

从岩石细观非均匀性的特点出发,提出一个描述非均匀材料渗流和破裂相互作用的数值模型。在这个数值模型中,单元的力学、水力学性质根据统计分布而变化,以体现材料的随机不均质性,材料在开裂破坏过程中流体压力传递通过单元渗流,损伤耦合迭代来实现。算例表明,该模型能较好地模拟出岩石类材料在水力压裂作用下,微结构非均匀分布和不同围压比对破裂模式、失稳压力的影响,非均匀性导致试件的开裂压力、失稳压力明显不同,裂纹扩展路径不规则发展,模拟结果和实验结果较为一致。     

A Small-Molecule Diketopyrrolopyrrole-Based Dye for in vivo NIR-IIa Fluorescence Bioimaging

Organic small-molecule fluorophores with near-infrared IIa (NIR-IIa) emission have great potential in pre-clinical detection and inoperative imaging due to the high-spatial resolution and deep penetration. However, developments of the NIR-IIa fluorophores are still facing considerable challenges. In this work, a series of diketopyrrolopyrrole (DPP)-based fluorophores were designed and synthesized. Subsequently, nanomaterial T25@F127 with significant NIR-IIa emission properties was rationally prepared by encapsulating DPP-based fluorophore T25 , and was selected for fluorescence angiography and cerebral vascular microscopic imaging with nearly 800 μm penetrating depth and excellent signal-background ratio of 4.07 and 2.26 (at 250 and 400 μm), respectively. Furthermore, the nanomaterial T25@cRGD with tumor targeting ability can image tiny metastatic tumor on intestine with a small size of 0.3 mm×1.0 mm and high-spatial resolution (SBR=3.84). This study demonstrates that the nanomaterials which encapsulated T25 behave as excellent NIR-IIa fluorescence imaging agents and have a great potential for in vivo biological application.     

Ensuring population diversity in genetic algorithms: A technical note with application to the cell formation problem

The entropy-based measure has been used in previous works to compute the population diversity in solving the cell formation problem with the genetic algorithm. Population diversity is crucial to the genetic algorithm’s ability to continue fruitful exploration as it may be used in choosing an initial population, in defining a stopping criterion, in evaluating the population convergence, and in making the search more efficient throughout the selection of crossover operators or the adjustment of various control parameters (e.g., crossover or mutation rate, population size). We show in this note that, when a non-ordinal chromosome representation corresponding to the allocation of machines to cells is used, the current way of measuring the population diversity is inaccurate. Consequently, it leads to wrong conclusions when, at various iterations, carrying out fruitful exploration or an efficient search of the solution space is guided by the perceived population diversity degree. An alternative approach based on computing the distance and the similarity between chromosomes is discussed.     

Heterogeneity of OH Groups in H-Mordenites TPD and IR studies of ammonia desorption

We have investigated the temperature-programmed desorption (TPD) of ammonia during the activation of NH4Na-mordenites of different exchange degrees. Using a regularization method, desorption energy distribution functions have been calculated. The obtained results indicate the heterogeneity of the bridging Si-OH-Al groups in HNa-mordenites. This was concluded from the width of the distribution functions and from the presence of submaxima. For HNa-mordenites of exchange degrees below 50%, containing only hydroxyls in the broad channels, two distinct submaxima are present, thus suggesting the presence of at least two kinds of bridging hydroxyls of various acid strengths. In HNa-mordenites of exchange degrees above 50%, the hydroxyls appear in narrow channels and the distribution of ammonia desorption energy broadens on the side of higher energies. This may be related to a strong stabilization of ammonium ions inside narrow channels. The maximum concentrations of hydroxyls of desorption energies between 95 and 135 kJ mol_-1 and between 135 and 165 kJ mol_-1 calculated from TPD data were 3.9 and 3.3 OH per unit cell (u.c.). These values agree well with our previous IR results of concentrations of hydroxyls in broad and in narrow channels (3.7 and 2.8 OH per u.c.). The TPD data obtained for the heterogeneity of OH groups in HNa-mordenites are in accordance with the IR data concerning ammonia desorption. The IR band of OH groups restoring upon saturation of all the hydroxyls with ammonia and subsequent step-by-step desorption at increasing temperatures shifts to lower frequencies indicating that there are hydroxyls of various acid strengths and the less acidic hydroxyls restore first at lower desorption temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.