渐近混合群体的混合连锁不平衡及其遗传连锁推断

在渐近混合模型中,混合现象发生在每一世代,通过对其混合连锁不平衡的理论分析,发现混合连锁不平衡与两个子群体间的基因频率差成正比。基于这一点,构造了一个对重组率严格单调的函数（△ker=△／（p1-p2）,其中△代表连锁不平衡）,进而据此推断标记基因座与疾病基因座的遗传连锁。应用人类基因组上不连锁的标记基因提供的连锁不平衡信息,基于病人组数据构造了一个准似然比统计量。模拟结果显示,此检验可用于精确的基因定位。文章亦讨论了参数对检验的影响。     

The Admixture Linkage Disequilibrium and Genetic Linkage Inference on the Gradual Admixture Population

Through the theoretical analysis of the admixture linkage disequilibrium (ALD) in the gradual admixture (GA) model, in which admixture occurs in every generation, the ALD is found to be proportional to the difference in marker allele frequencies, p₁-p₂, between two subpopulations. Based on this property, we can employ a strict monotonic function (Δ_ker=Δ/(p₁-p₂), where Δ denotes the linkage disequilibrium (LD)) of the recombination fraction between the marker locus and the disease locus to infer the true genetic linkage. We construct a quasi likelihood ratio test (LRT) for the case-only data utilizing the information of unlinked markers in the human genome. The simulation results show that our tests can be used to fine map a disease locus. The effects of parameter values in the ALD mapping are also discussed.     

青藏高原东缘生态过渡带碳中和评估与预测

青藏高原东缘生态过渡带是我国重要的生态功能区和碳库,对该区域碳中和的评估和预测对于中国乃至亚洲的碳排放管理具有重要意义。基于率定的CASA模型估算了2001-2019年青藏高原东缘生态过渡带栅格尺度碳汇量,结合中国碳排放数据库分析近20年碳排放时空演变规律;然后,采用STIRPAT模型和岭回归建立碳排放与人口等6个社会经济指标的弹性关系,并讨论库兹涅兹曲线对碳排放的影响。之后采用情景分析法,设计包括绿色发展等5种不同经济发展情景预测研究区2020-2060年碳排放变化特征;最后,提出假性碳中和并进行定义,结合GM （1,1）模型预测所得碳汇量,探究青藏高原东缘生态过渡带净碳汇量未来不同情景演变趋势,预测与评估不同发展情景研究区碳中和状况。结果表明：研究区碳汇量在2001-2019年间呈波动缓慢上升趋势,研究区碳汇量东南部高西北部较低;而碳排放量增长速率迅速,于2019年达到108Mt左右,是2001年的3.07倍;近20年,研究区碳汇量均大于碳排放量,但二者差距呈减少趋势。STIRPAT模型岭回归系数表明,研究区内存在城镇化率环境库兹涅兹曲线（EKC）效应,随着城镇化率的提升,区域碳排放呈先增加后减少趋势,而对于富裕度无显著EKC效应;在6个影响因素中,人口变量对碳排放的影响最显著,每增加1%的人口,碳排放将增加1.03%左右;在预测的五种不同发展情景中,可持续发展情景（ST）与基准情景（BL）、节能情景（ES）与绿色发展情景（GD）分别在2050年、2040年实现碳达峰,碳达峰时间随着能耗的减少逐渐提前。粗放情景（ETS）在2060年仍未实现碳达峰,并且其碳排放将于2040年左右超过碳汇量,而其余四种情景预测2020-2060年碳汇量始终大于碳排放量,但其净碳汇量均呈先减少后增加的趋势。因此,青藏高原东缘生态过渡带具有较强固碳能力,但如采用不加管制的发展模式,其碳汇量将无法抵消其碳排放量。因此,在规划发展模式与保护生态的同时,应重点控制人口、畜牧业等因素,提高人民与产业的节能减排意识。     

A three-state model for inactivation of sodium permeability

The inactivation of Na⁺ permeability in single myelinated motor nerve fibres of Rana esculenta was investigated under voltage and current clamp conditions at 20°C in Ringer's solution and under blocked K⁺ currents. Development of inactivation and its recovery was described by two potential-dependent time constants: The smaller time constant followed the usual bell-shaped function of membrane potential, whereas the larger one was monotone-increasing with more negative potentials. Several three-state models for inactivation were investigated. The experiments could best be approximated by a model with two open and one closed state for inactivation following: open ? closed ? open. Rate constants were determined for all transitions shown from the voltage clamp experiments. The action potentials computed by means of the proposed model were in good agreement with those measured, both in Ringer's solution and under blocked K⁺ current conditions.     

Interaction of monovalent cations with Rb+ and Na+ uptake in yeast

The concentration dependence of both Rb⁺ uptake and Na⁺ uptake by yeast can be described by a quadratic rate equation. This equation is derived for translocation of cations via a two-site translocation system. In accordance with predictions made for such a two-site translocation system the shape of the uptake isotherm depends both upon the substrate cation species and upon the concentration of other added competing cations. On plotting the rate of Rb⁺ uptake against the quotient of that rate and the Rb⁺ concentration concave, convex and also linear curves are found depending upon the type and the concentration of added monovalent cations. The Na⁺ uptake isotherm plotted in a similar way shows a shift from a concave curve to a straight line on adding increasing amounts of Rb⁺ to the yeast suspension.Decreasing the pH of the medium leads to a more pronounced convex     

Barley morphology, genetics and hormonal regulation of internode elongation modelled by a relational growth grammar

A multiscaled ecophysiological model of barley (Hordeum vulgare) development is presented here. The model is based on the new formalism of relational growth grammars (RGG), an extension of L-systems, and implemented using the new modelling language XL. It is executable in the interactive modelling platform GroIMP. The model consists of a set of morphogenetic rules, combined with a metabolic regulatory network, which simulates the biosynthesis of gibberellic acid (GA1). GA1 and two of its metabolic precursors are transported along the developing simulated structure. Local concentrations of GA1 determine internode elongation. Furthermore, virtual barley individuals are chosen interactively from a population, based on genotype, and (sexual or asexual) reproduction is simulated. Genotype and phenotype of the population are visualized. Seven Mendelian genes have been implemented in the model so far; some of these directly influence the GA-regulation network. The model exemplifies and validates the new formalism and modelling language. RGG have the capability to represent genetic, metabolic and morphological aspects of plant development and reproduction, all within the same framework.     

大鼠视网膜变性相关组织形态及功能研究

目的　探讨视网膜变性RCS (RoyalCollegeSurgeon)大鼠的视网膜形态及功能特点。 方法　应用HE染色、免疫组化染色和眼电生理技术 ,对比研究正常和变性两组大鼠视网膜特点。结果　 1 RCS大鼠在 3月龄时 ,视网膜外核层和感光细胞内外节完全消失 ;突触素免疫组化染色显示外丛状层不着色 ;视紫红质免疫组化染色显示原视网膜外层部位有阳性反应 ;胶质纤维酸性蛋白染色显示原视网膜外层部位有强阳性反应。 2 RCS大鼠的闪光视网膜电图 (flashelectronicretinogram ,FERG)a、b波振幅较正常Wistar大鼠明显降低 (P <0 0 1)。结论　在形态和功能上 ,3月龄RCS大鼠视网膜与人类晚期视网膜色素变性极为相似 ,因此可用于视网膜联合移植研究。     

Modeling Basic Industries in the Australian Stocks and Flows Framework

The Australian stocks and flows framework (ASFF) is a tool for establishing a coherent historical picture of the Australian physical economy and for testing long-term future scenarios (up to 2050 or even 2100). These scenarios can be used to investigate the long-term physical consequences of current and future choices affecting the physical dimensions of sustainability. In this article we describe the methodology for and construction of a key component of ASFF: a dynamic physical input-output model of material flows in the basic industries.
The materials model in ASFF describes physical flows and their transformation by industrial processes. The model's structure permits scenario analysis of long-term technological change by permitting time-varying input-output coefficients and vintage models of capital stocks. As a consequence, the model contains a large number of parameters, which can be left at default settings or adjusted as the modeler sees fit, in order to simulate the widest possible range of physically realizable scenarios. The materials model is built using a methodology that integrates bottom-up process analysis with top-down statistics on material and energy flows. We present some examples showing how the materials model has been implemented to model Australian heavy industries. Several possibilities for further developing the materials model are also described.