元胞自动机在环境科学中的应用

阐述了元胞自动机(Cellular Automata)的基本原理、方法,总结了CA的甚本特点和适用范围,并又探讨了其在环境科学和生态学中的应用．     

禁止字方法在元胞自动机中的一个应用

给出了使用禁止字理论、计算机搜索和符号动力学研究初等元胞自动机演化语言的一种方法，并且使用该方法得到了27号初等元胞自动机演化语言在数学上的精确描述．     

元胞自动机中斑图复制的识别算法

给出了元胞自动机中斑图复制识别的一种算法。通过定义每个元胞的特征数,将两个斑图统一放入一个区域内比较它们的特征数,从而判定是否出现复制现象。数值例子表明,该算法是有效的。     

Sub-classes and evolution stability of Wolfram's classes in the total-rule cellular automata

Cellularautomata(CA)aremathematicalmodelsforcomplexnaturalsystemscontaininglargernumbersofsimpleidenticalcomponentswithlocalinteractions.TheCAconsistofalatticeofsites,eachwithafinitesetofpossiblevalues.Thesitevaluesevolvesynchronouslyineverytimestep[1～4].Onecellularautomatonconsistsoffourparts:theevolutionrule,theformofgeometricalneighborhood,theinitialconfigurationandtheclock.Whentheclockshowsthattimegoesforwardforonestep,configurationoftheCAupdatesonce.Generally,theevolutionrulesofCAare…     

移动通信网络环境下的用户运动模式挖掘

为解决移动用户运动规律获取问题,提出了一种在移动通信网络(GSM)环境下,从用户低层基站位置信息中提取出运动模式的方法.针对基站连接的振荡、重叠等问题,该方法对原始基站位置数据进行分段、窗口化、分组和聚类处理,并将原始基站位置数据表示为聚类序列.采用关联规则挖掘算法从聚类序列中提取出用户运动模式.最后,基于真实基站位置...     

元胞自动机慢启动规则交通流模型的能耗研究

文章对TT、BJH和VDR 3种典型的慢启动规则元胞自动机交通流模型的能耗和能量耗散进行了研究,通过分析NaSch模型车辆在加速、确定减速和随机减速3个过程的做功,提出元胞自动机交通流模型的平均能耗公式和平均能量耗散公式,通过数值模拟分别讨论了在周期边界条件下车辆的能耗和能量耗散。结果表明,车辆的加速的能耗和减速的能量耗散相等,能耗和能量耗散与车辆初始分布的状态和演化规则有关。     

高校大型设备实验教学模式的探索与实践

结合2013年新颁布实施的高等学校建筑环境与能源应用工程本科指导性专业规范,针对目前高校存在的大型实验设备利用率低及运转不畅的现象,将散热器热工性能实验装置引入本科教学,构建多层次综合性实验平台,采用定期开放和预约开放的管理模式,革新了传统实验项目,对培养学生的理论联系实践的能力、创新能力及分析解决问题的能力具有重要的现实意义。     

Cellular interactions in haematopoiesis.

In vitro culture of haematopoietic cells has provided some surprising insights into critical interactions of blood-forming cells. Subpopulations of lymphoid cells have been shown to produce colony-stimulating activity, to interact with macrophages, and to have important effects on the very early stages of erythropoiesis. Macrophages have multiple influences on the proliferation and differentiation of other haematopoietic cells.     

在Rashba和Dresselhaus自旋轨道耦合相互作用下二端双通道中的局域自旋极化研究

研究二端双通道结构中同时存在Rashba和Dresselhaus两种自旋轨道耦合相互作用情况下的电子局域自旋极化.本结构中所产生的局域自旋极化是由量子干涉效应和自旋轨道耦合共同导致的,因此可以通过调节结构参数和门电压的大小来改变局域自旋极化的大小.在适当选取某些参数的情况下.局域自旋极化可以达到0.33,可以用于自旋过滤器和信息储存器件.     

Local changes in snow depth dominate the evolving pattern of elevation-dependent warming on the Tibetan Plateau

Elevation-dependent warming (EDW),whereby warming rates are stratified by elevation,may increase the threat to the life-supporting solid water reservoir on the ...     

Bone histology. Evolution of growth pattern in birds

Living (neornithine) birds grow up rapidly and without interruption, terminating their growth within one year and, with a few secondary exceptions, starting to fly only after or near the completion of growth. Bone histology has revealed that pre-avian theropods also grew fast for most of the postnatal period, but that this growth was usually intermittent and probably extended for more than one year. We have found surprising evidence for an early postnatal slowing-down of growth in two lineages of flying basal birds, which suggests that birds may have started their evolution as precocious fliers.     

Evidence for cooperative interactions in potassium channel gating.

Cloning and expression of voltage-activated potassium ion-channel complementary DNAs has confirmed that these channels are composed of four identical subunits, each containing a voltage sensor. It has been generally accepted that the voltage sensors must reach a permissive state through one or more conformational ('gating') transitions before the channel can open. To test whether each subunit gates independently, we have constructed cDNAs encoding four subunits on a single polypeptide chain, enabling us to specify the subunit stoichiometry. The gating of heterotetramers made up from combinations of subunits with different gating phenotypes strongly suggests that individual subunits gate cooperatively, rather than independently. Nonindependent subunit gating is consistent with measurements of the kinetics of K(+)-channel gating currents and in line with the widespread subunit cooperativity observed in other multisubunit proteins.     

Symmetry in locomotor central pattern generators and animal gaits.

Animal locomotion is controlled, in part, by a central pattern generator (CPG), which is an intraspinal network of neurons capable of generating a rhythmic output. The spatio-temporal symmetries of the quadrupedal gaits walk, trot and pace lead to plausible assumptions about the symmetries of locomotor CPGs. These assumptions imply that the CPG of a quadruped should consist of eight nominally identical subcircuits, arranged in an essentially unique matter. Here we apply analogous arguments to myriapod CPGs. Analyses based on symmetry applied to these networks lead to testable predictions, including a distinction between primary and secondary gaits, the existence of a new primary gait called 'jump', and the occurrence of half-integer wave numbers in myriapod gaits. For bipeds, our analysis also predicts two gaits with the out-of-phase symmetry of the walk and two gaits with the in-phase symmetry of the hop. We present data that support each of these predictions. This work suggests that symmetry can be used to infer a plausible class of CPG network architectures from observed patterns of animal gaits.     

Orientation of DNA replication establishes mating-type switching pattern in S. pombe.

The fission yeast Schizosaccharomyces pombe normally has haploid cells of two mating types, which differ at the chromosomal locus mat1. After two consecutive asymmetric cell divisions, only one in four 'grand-daughter' cells undergoes a 'mating-type switch', in which genetic information is transferred to mat1 from the mat2-P or mat3-M donor loci. This switching pattern probably results from an imprinting event at mat1 that marks one sister chromatid in a strand-specific manner, and is related to a site-specific, double-stranded DNA break at mat1. Here we show that the genetic imprint is a strand-specific, alkali-labile DNA modification at mat1. The DNA break is an artefact, created from the imprint during DNA purification. We also propose and test the model that mat1 is preferentially replicated by a centromere-distal origin(s), so that the strand-specific imprint occurs only during lagging-strand synthesis. Altering the origin of replication, by inverting mat1 or introducing an origin of replication, affects the imprinting and switching efficiencies in predicted ways. Two-dimensional gel analysis confirmed that mat1 is preferentially replicated by a centromere-distal origin(s). Thus, the DNA replication machinery may confer different developmental potential to sister cells.     

A whole genome approach to in vivo DNA-protein interactions in E. coli.

The increasingly rapid pace at which genomic DNA sequences are being determined has created a need for more efficient techniques to determine which parts of these sequences are bound in vivo by the proteins controlling processes such as gene expression, DNA replication and chromosomal mechanics. Here we describe a whole-genome approach to identify and characterize such DNA sequences. The method uses endogenous or artificially introduced methylases to methylate all genomic targets except those protected in vivo by protein or non-protein factors interfering with methylase action. These protected targets remain unmethylated in purified genomic DNA and are identified using methylation-sensitive restriction endonucleases. When the method was applied to the Escherichia coli genome, 0.1% of the endogenous adenine methyl-transferase (Dam methylase) targets were found to be unmethylated. Five foreign methylases were examined by transfection. Database-matched DNA sequences flanking the in vivo-protected Dam sites all fell in the non-coding regions of seven E. coli operons (mtl, cdd, flh, gut, car, psp and fep). In the first four operons these DNA sequences closely matched the consensus sequence that binds to the cyclic AMP-receptor protein. The in vivo protection at the Dam site upstream of the car operon was correlated with a downregulation of car expression, as expected of a feedback repressor-binding model.     

地方院校体育课程改革的思考

通过对文献资料的研究和实际调查,并根据新时期大学体育课程改革的目标,对地方高校体育课程改革提出一些思路和对策.     

Abnormal pattern detected in fragile-X patients by pulsed-field gel electrophoresis.

The fragile-X syndrome is the most frequent inherited form of mental retardation, with an incidence of 1 in 1,500 males. It is characterized by the presence of a fragile site at Xq27.3 induced in vitro by folate deprivation or by inhibitors of deoxynucleotide synthesis. Its mode of inheritance is unusual for an X-linked trait, with incomplete penetrance in both males and females. Some phenotypically normal males transmit the mutation to all their daughters who rarely express any symptoms, but penetrance is high in sons and daughters of these carrier women. Genetic and physical mapping of the Xq27-q28 region has confirmed that the disease locus is located at or very near the fragile site. Hypotheses proposed to account for the abnormalities in the inheritance of the disease include sequence rearrangements by meiotic recombination or a mutation that affects reactivation of an inactive X chromosome during differentiation of female germ cells. To detect such rearrangements, or methylation changes that may reflect a locally inactive X chromosome, we used pulsed-field gel analysis of DNA from fragile-X patients with probes close to the fragile-X locus. The probe Do33 (DXS465) detected abnormal patterns in fragile-X patients, but not in normal controls or in non-expressing male transmitters.     

具有R.S.S.结构的GMANOVA-MANOVA模型的影响分析

该文主要讨论具有Ｇ．Ｒ．Ｒａｏ简单协方差结构的ＧＭＡＮＯＶＡ－ＭＡＮＯＶＡ模型的局部影响分析问题,依据似然函数,采用曲率度量来评价微小扰动（这里主要指协方差扰动）对统计推断的影响。     

Genome complexity, robustness and genetic interactions in digital organisms.

Digital organisms are computer programs that self-replicate, mutate and adapt by natural selection. They offer an opportunity to test generalizations about living systems that may extend beyond the organic life that biologists usually study. Here we have generated two classes of digital organism: simple programs selected solely for rapid replication, and complex programs selected to perform mathematical operations that accelerate replication through a set of defined 'metabolic' rewards. To examine the differences in their genetic architecture, we introduced millions of single and multiple mutations into each organism and measured the effects on the organism's fitness. The complex organisms are more robust than the simple ones with respect to the average effects of single mutations. Interactions among mutations are common and usually yield higher fitness than predicted from the component mutations assuming multiplicative effects; such interactions are especially important in the complex organisms. Frequent interactions among mutations have also been seen in bacteria, fungi and fruitflies. Our findings support the view that interactions are a general feature of genetic systems.