Self-organized patchiness in asthma as a prelude to catastrophic shifts

Asthma is a common disease affecting an increasing number of children throughout the world. In asthma, pulmonary airways narrow in response to contraction of surrounding smooth muscle. The precise nature of functional changes during an acute asthma attack is unclear. The tree structure of the pulmonary airways has been linked to complex behaviour in sudden airway narrowing and avalanche-like reopening. Here we present experimental evidence that bronchoconstriction leads to patchiness in lung ventilation, as well as a computational model that provides interpretation of the experimental data. Using positron emission tomography, we observe that bronchoconstricted asthmatics develop regions of poorly ventilated lung. Using the computational model we show that, even for uniform smooth muscle activation of a symmetric bronchial tree, the presence of minimal heterogeneity breaks the symmetry and leads to large clusters of poorly ventilated lung units. These clusters are generated by interaction of short- and long-range feedback mechanisms, which lead to catastrophic shifts similar to those linked to self-organized patchiness in nature. This work might have implications for the treatment of asthma, and might provide a model for studying diseases of other distributed organs.     

中国交通运输业全要素生产率地区差异的实证研究

在构建1984—2010年中国30个省(区、市)交通运输业面板数据的基础上,同时采用LLC检验、IPS检验、Breiting检验、ADF-F检验和PP-F检验等方法对面板数据进行了单位根检验,采用EG两步法对变量之间的协整关系进行了检验.实证研究的检验结果表明,中国交通运输业的全要素生产率(TFP)存在明显的地区差异,地区间及地区内部资金、技术、劳动力等要素投入是引起差异的主要原因.运用σ收敛法考察了1984—2010年中国各地区交通运输业TFP的收敛性,检验表明,中国交通运输业TFP在三大区域之间和区域内部都存在发散的趋势.政府应注重交通运输业的规划、管理,通过适当的政策调节地区差距,鼓励地区间的学习、模仿和技术流动,以促进交通运输业在各地区的协调发展.     

肺微血管研究进展

综述了脊椎动物肺微血管构筑的研究进展及特点．两栖动物在囊状肺的内表面出现了网状隔膜与次级隔膜，以增加气体交换面积，提高气体交换率；爬行动物肺内壁上不仅有网状隔膜和次级隔膜，还出现了三级隔膜，使得动物肺壁内表面积有较大增加，显示其结构比两栖动物有较大进步，更有利于进行气体交换；鸟肺三级支气管与周围放射状紧密排列的微气管结构上排列着丰富的毛细血管网，并相互吻合成密集的立体微血管网，呼吸表面积大为增加，比两栖、爬行动物又有更大进步；哺乳动物和人肺则由发达的支气管系统及大量的肺泡囊与肺泡构成，肺泡与肺泡隔毛细血管为密集网，显示肺结构有极大的呼吸表面积，更有利于血液与进入肺内的空气进行气体交换．肺脏微血管的三维构筑特点及变化充分显示了动物与生存环境相适应的结构特点，亦体现出生物由低等向高等进化过程中结构与功能相适应的规律．     

T cells become licensed in the lung to enter the central nervous system

The blood–brain barrier (BBB) and the environment of the central nervous system (CNS) guard the nervous tissue from peripheral immune cells. In the autoimmune disease multiple sclerosis, myelin-reactive T-cell blasts are thought to transgress the BBB and create a pro-inflammatory environment in the CNS, thereby making possible a second autoimmune attack that starts from the leptomeningeal vessels and progresses into the parenchyma. Using a Lewis rat model of experimental autoimmune encephalomyelitis, we show here that contrary to the expectations of this concept, T-cell blasts do not efficiently enter the CNS and are not required to prepare the BBB for immune-cell recruitment. Instead, intravenously transferred T-cell blasts gain the capacity to enter the CNS after residing transiently within the lung tissues. Inside the lung tissues, they move along and within the airways to bronchus-associated lymphoid tissues and lung-draining mediastinal lymph nodes before they enter the blood circulation from where they reach the CNS. Effector T cells transferred directly into the airways showed a similar migratory pattern and retained their full pathogenicity. On their way the T cells fundamentally reprogrammed their gene-expression profile, characterized by downregulation of their activation program and upregulation of cellular locomotion molecules together with chemokine and adhesion receptors. The adhesion receptors include ninjurin 1, which participates in T-cell intravascular crawling on cerebral blood vessels. We detected that the lung constitutes a niche not only for activated T cells but also for resting myelin-reactive memory T cells. After local stimulation in the lung, these cells strongly proliferate and, after assuming migratory properties, enter the CNS and induce paralytic disease. The lung could therefore contribute to the activation of potentially autoaggressive T cells and their transition to a migratory mode as a prerequisite to entering their target tissues and inducing autoimmune disease.     

新生牛肝脏中肝细胞生长因子（cHGF）的分离纯化及性质研究

从新生牛肝脏分离纯化到一种具有刺激肝源性ＳＭＭＣ—７７２１人肝癌细胞和原代培养的人胎肝细胞ＤＮＡ合成的单一组分，命名为小牛肝细胞生长因子（ｃａｌｆｈｅｐａｔｏｃｙｔｅｇｒｏｗｔｈｆａｃｔｏｒ，ｃＨＧＦ），测得分子量为３９．８ｋｄ，蒽酮法测得糖含量极少，部分纯化的ｃＨＧＦ在与胰岛素和表皮生长因子混合使用时活性有一定增加，对ＣＣｌ４处理的肝坏死大鼠有明显的促肝再生功能。     

用于计算机辅助诊断的肺实质自动分割方法

在肺结节的计算机辅助诊断过程中,肺实质的分割是关键的步骤。传统的肺部分割方法都是基于肺实质与周围组织对X线的衰减强度不同而进行的。这些方法对正常的肺部能得到理想的结果,但当肺部存在肺结节等异常征象时,这些方法会出现错误。该文提出了一套完整肺实质分割流程,首先用阈值法和边界跟踪算法得到初始的肺部轮廓,然后提出一种新的基于计算局部二维凸包的方法对原始的肺部轮廓进行修正。该算法能将与肺部周围组织相连的肺结节包括在肺实质中,从而在肺部存在与胸膜相连的结节的情况下也能得到满意的分割结果。采用该算法对6个病人的约400张肺部CT图像进行了肺实质提取,实验结果显示:该算法对正常和异常征象的肺部CT图像进行分割的正确率均能达到83%以上,为肺结节的计算机诊断提供了良好的条件。     

The branching programme of mouse lung development

Mammalian lungs are branched networks containing thousands to millions of airways arrayed in intricate patterns that are crucial for respiration. How such trees are generated during development, and how the developmental patterning information is encoded, have long fascinated biologists and mathematicians. However, models have been limited by a lack of information on the normal sequence and pattern of branching events. Here we present the complete three-dimensional branching pattern and lineage of the mouse bronchial tree, reconstructed from an analysis of hundreds of developmental intermediates. The branching process is remarkably stereotyped and elegant: the tree is generated by three geometrically simple local modes of branching used in three different orders throughout the lung. We propose that each mode of branching is controlled by a genetically encoded subroutine, a series of local patterning and morphogenesis operations, which are themselves controlled by a more global master routine. We show that this hierarchical and modular programme is genetically tractable, and it is ideally suited to encoding and evolving the complex networks of the lung and other branched organs.     

基于面板数据的我国入境旅游经济与接待人数研究

运用空间回归模型,选取中国大陆31个省份2003~2011年旅游外汇收入等相关面板数据指标,实证研究了我国入境旅游经济与接待人数之间的关系.结果表明:入境旅游经济与入境旅游人数存在正相关、稳定性以及长期动态均衡关系.在相同入境旅游人数的情况下,发达地区的旅游外汇收入高于其他地区;甘肃、湖南、山西3省接待人数对入境旅游经济的影响最大;新疆、海南、甘肃、青海等地的入境旅游经济对接待人数的依赖程度极强.     

我国外汇储备规模的影响因素分析与实证检验

我国的外汇储备一直是一个令人关注的问题。本文通过分析影响我国外汇储备规模的各种因素,运用回归分析方法建立了我国外汇储备模型,并且运用历史数据进行实证分析和拟合检验,其效果十分显著,这说明所建立的模型是能够充分体现我国外汇储备的数量关系,最后针对我国外汇储备的实际提出了规模管理的一些政策建议。     

Slow-reacting substances (leukotrienes) contract human airway and pulmonary vascular smooth muscle in vitro

During a type I allergic reaction histamine, slow-reacting substance of anaphylaxis (SRS-A) and other mediator substances are elaborated from specific tissue sites. In allergic asthma these sites are in the lung and the mediator substances cause airway obstruction by contracting smooth muscle and altering mucociliary function. Unlike histamine, slow-reacting substances (SRSs) have been assessed very little for their roles in obstructive airways disease. This has been partly due to the fact that their chemical nature was unknown until recently and thus pure samples were not available for pharmacological studies. However, SRSs isolated from both immunological and non-immunological reactions have been identified as a combination of two related lipid substances--leukotriene C4 (LTC) and leukotriene D4 (LTD); thus it is now possible to use pure SRSs (leukotrienes) in pharmacological studies of airway smooth muscle. LTC and LTD have been shown to contract guinea pig tracheal and lung parenchymal strips but there is no evidence that these substances produce similar effects on human lung tissue. To clarify this, in vivo pharmacological studies were done to determine the actions of LTC and LTD on smooth muscle strips of human bronchus, pulmonary vein and artery, and lung parenchymal tissue containing smooth muscle components and pleura. As indicated in a preliminary report, all four types of tissues contracted in a dose-dependent fashion to the leukotrienes, although these substances only function as partial agonists.     

Equilibrium lithium transport between nanocrystalline phases in intercalated TiO(2) anatase

Microcrystalline TiO(2) with an anatase crystal structure is used as an anode material for lithium rechargeable batteries, and also as a material for electrochromic and solar-cell devices. When intercalated with lithium, as required for battery applications, TiO(2) anatase undergoes spontaneous phase separation into lithium-poor (Li(0.01)TiO(2)) and lithium-rich (Li(0.6)TiO(2)) domains on a scale of several tens of nanometres. During discharge, batteries need to maintain a constant electrical potential between their electrodes over a range of lithium concentrations. The two-phase equilibrium system in the electrodes provides such a plateau in potential, as only the relative phase fractions vary on charging (or discharging) of the lithium. Just as the equilibrium between a liquid and a vapour is maintained by a continuous exchange of particles between the two phases, a similar exchange is required to maintain equilibrium in the solid state. But the time and length scales over which this exchange takes place are unclear. Here we report the direct observation by solid-state nuclear magnetic resonance of the continuous lithium-ion exchange between the intermixed crystallographic phases of lithium-intercalated TiO(2). We find that, at room temperature, the continuous flux of lithium ions across the phase boundaries is as high as 1.2 x 10(20) s(-1) m(-2).     

Extrusion of calcium from rod outer segments is driven by both sodium and potassium gradients

Calcium is transported across the surface membrane of both nerve and muscle by a Na+-dependent mechanism, usually termed the Na:Ca exchange. It is well established from experiments on rod outer segments that one net positive charge enters the cell for every Ca2+ ion extruded by the exchange, which is generally interpreted to imply an exchange stoichiometry of 3 Na+:1 Ca2+. We have measured the currents associated with the operation of the exchange in both forward and reversed modes in isolated rod outer segments and we find that the reversed mode, in which Ca2+ enters the cell in exchange for Na+, depends strongly on the presence of external K+. The ability of changes in external K+ concentration ([K+]o) to perturb the equilibrium level of [Ca2+]i indicates that K+ is co-transported with calcium. From an examination of the relative changes of [Ca2+]o, [Na+]o, [K+]o and membrane potential required to maintain the exchange at equilibrium, we conclude that the exchange stoichiometry is 4 Na+:1 Ca2+, 1 K+ and we propose that the exchange should be renamed the Na:Ca, K exchange. Harnessing the outward K+ gradient should allow the exchange to maintain a Ca2+ efflux down to levels of internal [Ca2+] that are considerably lower than would be possible with a 3 Na+:1 Ca2+ exchange.     

人民币与国际汇率的非线性特征研究

采用BDS检验和R/S方法揭示了2种人民币汇率和3种国际汇率日收益率序列是确定性分形序列.研究结果表明,上述汇率序列不服从正态分布和布朗运动,并且具有内在的非线性分形结构,人民币兑日元的汇率波动关联性比其它汇率的波动性高,反映出人民币兑日元汇率波动受历史信息的影响程度较高,其"长期记忆"特征也越明显,有助于进一步深入分析汇率的内在机理以及对汇率进行预测.     

研究E^＊-Ω相互作用

手征SU（3）夸克模型和推广手征SU（3）夸克模型的短程相互作用机制完全不同,一种来源于单胶子交换,另一种来源于矢量介子交换．在这两个模型中研究了E^＊-Ω相互作用,对可能形成（E^＊-Ω）ST=01/2束缚态的原因进行了探讨．主要分析了这两个模型不同的短程相互作用机制,分析了手征场相互作用及夸克交换效应的影响．计算结果表明,尽管单胶子交换和矢量介子交换机制不同,但在这两个模型中此系统都会形成深束缚态．其主要原因,一是由于σ手征场提供的强吸引相互作用,二是由于它具有特殊的对称性,使夸克交换效应有利于深束缚态的形成．     

基于连续最大流的三维肺实质快速分割算法

肺结节是肺癌的表征形式,形状结构多样且易与正常组织产生粘连,使分割存在困难.提出了一种基于空间约束的三维肺实质分割算法,实现对肺实质组织的分割及目标区域的获取.首先使用SLIC方法将二维CT序列图像构建成超像素图像矩阵,并对矩阵进行稀疏化处理,降低矩阵维度.然后连接相邻切片间的超像素构造肺实质组织的三维结构.最后采用连续最大流方法对构造的三维肺部结构进行分割.实验结果表明,所提算法能够快速准确地分割三维肺实质组织,对不同类型肺结节的分割均取得较好结果,具有一定的临床应用价值.     

Deletion of a DNA sequence at the chromosomal region 3p21 in all major types of lung cancer

In childhood malignancies such as retinoblastoma and Wilms tumour, of which both familial and sporadic forms exist, recessive mutations of presumed differentiation genes have been implicated in tumorigenesis. A proportion of cases appear with microscopically visible chromosome deletions which indicate the regions where the genes concerned are located. Mutation or loss of one allele causes a cancer predisposition. For tumour development functional loss of the remaining normal allele is also required. In cancers with both familial and sporadic forms, molecular-genetic studies have shown that deletion is often one of the mutational events. Although familial and sporadic forms have never been distinguished in lung cancer, deletions of the short arm of chromosome 3 have been described for small cell lung cancer (SCLC), but their general occurrence in SCLC has been disputed. Using a molecular-genetic approach, we here present evidence for a consistent deletion at the chromosomal region 3p21, not only in SCLC, but in all major types of lung cancer.     

消除XML路径冗余算法

路径冗余是XML数据冗余的一种情况,特别是在云环境下,将直接影响XML作为不同程序间数据表示和数据交换的应用。文章在已有知识基础上,考虑XML层次结构特点,综合讨论了树结构中结点间语义约束与路径冗余的关系,并给出FD和MVD导致的数据异常问题解决的定理、算法及正确性证明。     

基于时间序列的数据挖掘在证券中的应用

为更好地对股票数据进行分析,从理论上对数据挖掘中时间序列的产生、应用进行了研究,通过对时间序列处理以及相关性搜索的多种方法的比较和分析,设计一个以股票预测为对象的小型系统。该系统首先对时间序列进行适当的处理,然后进行相似性搜索,分析未来的短时间的走势是否是历史上的重现。同时对得到的结果进行了分析,实验结果表明,该方法能找到股票数据中历史上相似走势,并通过历史走势分析当前的走势。     

泛函分析在炉子最优控制中的应用

阐述了炉子最优控制中确定目标函数的困难，在于炉膛换热在模型中被充分简化，从而使真实目标与保留参量脱耦。提出以炉膛和被加热热金属两部分的简化能量平衡式构成目标函数，并以变分法导出可求目标极值的微分方程。