Bayesian experimental design for nonlinear mixed-effects models with application to HIV dynamics

Bayesian experimental design is investigated for Bayesian analysis of nonlinear mixed-effects models. Existence of the posterior risk for parameter estimation is shown. When the same prior distribution is used for both design and inference, existence of the preposterior risk for design is also proven. If the prior distribution used in design is different from that used for inference, sufficient conditions are established for existence of the preposterior risk for design. A case study of design for an experiment in population HIV dynamics is provided.     

草基-鱼塘生态系统的能量转化与养分循环研究

应用模拟试验的方法,研究了“草基-鱼塘”系统中的能量转化与养分循环.结果表明,该系统中饲草对太阳能的利用率为0.83%,鱼对饲料能的转化率为7.3%.与以粮食作为鱼饲料比较,单位面积草地的产鱼当量是粮食作物的1.6倍.鱼对饲料N、P、K的转化率分别为16.8%、32.3%和2.0%.塘泥沉积的N、P分别占饲料的23.4%和56.1%;猪对饲料N、P、K的转化率分别为20.5%、33.7%和4.6%,猪粪尿回收饲料N为36.4%、P为63.8%、K为39.4%.猪-草-鱼结合的基塘系统其能量和养分转化效率均高于单一的养鱼系统.     

草基—鱼塘生态系统的能量转化与养分循环研究

应用模拟试验的方法,研究了“草基-鱼塘”系统中的能量转化与养分循环．结果 表明,该系统中饲草对太阳能的利用率为 ０． ８３％,鱼对饲料能的转化率为 ７． ３％．与以粮 食作为鱼饲料比较,单位面积草地的产鱼当量是粮食作物的１．６倍．鱼对饲料Ｎ、Ｐ、Ｋ的 转化率分别为１６．８％、３２．３％和２．０％．塘泥沉积的Ｎ、Ｐ分别占饲料的２３．４％和５６．１％; 猪对饲料 Ｎ、 Ｐ、 Ｋ的转化率分别为 ２０． ５％、 ３３． ７％和 ４． ６％,猪粪尿回收饲料 Ｎ为 ３６． ４％、 Ｐ为 ６３． ８％、 Ｋ为 ３９． ４％．猪-草-鱼结合的基塘系统其能量和养分转化效率均高于单一的 养鱼系统．     

湖南土家族的体质特征

以20至69岁的湖南土家族人为观察测量对象,根据1392人(男896,女496)的身高,1038人(男668,女370)的头部测量,364人(男235,女129)的五官测量和观察结果,分析该民族的体质特征,并与国内其他民族相比较。     

"基因电脑克隆"软件SiClone的并行优化研究与实现

生物信息学中,发现、鉴别新基因是承上启下的一步,它既承接了过往如“基因组测序”的工作,又是未来“后基因时代”研究的基石．“基因电脑克隆”是利用计算手段发现、鉴别新基因的方法,SiClone软件实现了“基因电脑克隆”功能．本文对SiClone软件操作的数据库提出并行处理方案,并详述了基于MPI(message passing interface)平台实现的并行优化版本PSiClone．根据已得到的EST数据库,展示了软件并行版PSiClone的运行性能,试验数据库EST序列条数仅仅是NCBI(The National Center for Biotechnology Information)dbEST庞大数据库的很小部分,这也暗示我们软件的并行工作对于大数据库的比较和运算将更有应用前景．     

维吾尔族的体质特征研究

１９９１年５月,对新疆伊梨维吾尔族５２９人（男２７１,女２５８）进行了活体观察和测量。观察２９项,测量９２项。维吾尔族的主要特征是：黑直发,黑褐色眼,眉毛较浓密,大都有上眼脸皱褶,鼻根中等偏高,大多为直形鼻,鼻尖向前,鼻基部下垂,大多有达尔文结节,耳垢湿型。头面部指数分型,属于特短头型,阔头型和高头型。身材中等偏高,平均身高男１６８．６毫米,女１５７８．８毫米。     

Does bone mineralization reflect economic conditions? An examination using a national US sample

BACKGROUND: Bone density is the most important determinant of osteoporotic fractures, which lead to significant morbidity, disability and mortality for older persons, particularly women. Sensitive periods for bone mineralization in infancy, childhood and adolescence overlap with those for height attainment. After peak density is reached in early adulthood, there is age-related decline. We ask whether bone density, as height, reflects economic conditions. SUBJECTS AND METHODS: Using the third National Health and Nutrition Examination Survey, a probability sample of the US population which over-sampled Blacks and Mexican Americans, we examine the associations between adult bone mineral content (BMC) adjusted for bone and body size and three economic indicators: education, height and the poverty income ratio (PIR). We compare four groups: US-born Whites, Blacks and Mexican Americans and Mexican-born Mexican Americans. RESULTS: Education is positively associated with BMC only for White women, although there are similar, non-significant associations for Black women and White and Black men. For women, BMC is more strongly associated with height for Mexican Americans, especially the Mexican-born, than for Whites. For men, the only significant association is a negative one with education for men born in Mexico. PIR is not significantly associated with BMC, although there is pattern of lower income being associated with lower BMC for Whites and Blacks and higher BMC for Mexican Americans. CONCLUSION: Bone density does not reflect economic conditions as strongly or consistently as does physical stature. However, for women there is evidence that lower economic status in childhood or adolescence is associated with lower bone density.     

The transmembrane nucleoporin NDC1 is required for targeting of ALADIN to nuclear pore complexes

NDC1 is a transmembrane nucleoporin that is required for NPC assembly and nucleocytoplasmic transport. We show here that NDC1 directly interacts with the nucleoporin ALADIN, mutations of which are responsible for triple-A syndrome, and that this interaction is required for targeting of ALADIN to nuclear pore complexes (NPCs). Furthermore, we show that NDC1 is required for selective nuclear import. Our findings suggest that NDC1-mediated localization of ALADIN to NPCs is essential for selective nuclear protein import, and that abrogation of the interaction between ALADIN and NDC1 may be important for the development of triple-A syndrome.     

SIR-SVS epidemic models with continuous and impulsive vaccination strategies

Vaccination is important for the control of some infectious diseases. This paper considers two SIR-SVS epidemic models with vaccination, where it is assumed that the vaccination for the newborns is continuous in the two models, and that the vaccination for the susceptible individuals is continuous and impulsive, respectively. The basic reproduction numbers of two models, determining whether the disease dies out or persists eventually, are all obtained. For the model with continuous vaccination for the susceptibles, the global stability is proved by using the Lyapunov function. Especially for the endemic equilibrium, to prove the negative definiteness of the derivative of the Lyapunov function for all the feasible values of parameters, it is expressed in three different forms for all the feasible values of parameters. For the model with pulse vaccination for the susceptibles, the global stability of the disease free periodic solution is proved by the comparison theorem of impulsive differential equations. At last, the effect of vaccination strategies on the control of the disease transmission is discussed, and two types of vaccination strategies for the susceptible individuals are also compared.     

鼠疫菌噬菌体效价噬菌斑测定法的建立

目的建立鼠疫菌噬菌体噬菌斑效价测定方法。方法通过分析细菌接种浓度、孵育吸附时间及培养温度等参数,建立鼠疫菌噬菌体效价测定方法,并分析其精密性;建立鼠疫活疫苗鉴别及纯菌检查用噬菌体效价质量标准。结果经优化后确定细菌接种浓度为7×108/mL,不需孵育吸附,培养温度为29℃,所建立的检测方法精密性较好,用于鼠疫活疫苗鉴别及纯菌检查用噬菌体效价质量标准应不低于1×106PFU/mL。结论建立了鼠疫菌噬菌体噬菌斑效价测定方法,为鼠疫菌噬菌体及疫苗质量控制奠定了基础。     

On evaluation of infection probabilities for different age groups

It is well known that evaluation of parameters for any mathematical model is always very important and often a very difficult problem. This is especially true for agents-based models because as a rule the evaluation of an agent's parameters can be made only based on available information from the higher levels of a complex system. Such problems can be ill-posed or even have a non-unique solution. That is why there is no general algorithm for solving these problems and a researcher has to search for it for every specific model type.     

A likelihood approach for quantitative-trait-locus mapping with selected pedigrees

Selective sampling is a cost-effective design for mapping quantitative trait loci (QTLs). A unified framework, which naturally combines two complementary sources of linkage information in the data, is proposed for the mapping of QTLs using selected pedigrees. Score statistics for detecting linkage are introduced for single-locus models (univariate or bivariate phenotypes) and two-locus epistasis models. A computer implementation of the methods for single-locus univariate-phenotype models is provided for nuclear families with arbitrary number of sibs and is freely available.     

Swimbladder volume and body density in an armoured benthic fish, the streaked gurnard

Body density of streaked gurnards Trigloporus lastoviza is anomalously low (mean 1·043 g ml⁻¹) for a benthic fish and overlaps with that of pelagic fish such as cod and lumpfish. It is clear that the heavy armour of gurnards is offset by buoyancy provided by the swimbladder. Swimbladder volume is a mean 3·88% of gurnard volume. Evidence is given to indicate that this is quite large for a marine teleost: data are also presented to show that the '5% of fish volume for marine fish, 7% for freshwater fish' rule for swimbladder volumes is unreliable.     

Statistical Testing for Seasonality in Data with Multiple Peaks and Troughs

EDWARDS'S test for seasonality is extended to multiple peaks and troughs. It is shown how the extended statistic may be adjusted for the population at risk and for unequal lengths of time intervals in the cycle of seasons. A simulation study shows that the extended test statistic is, for sample sizes N ≧ 100, very specific in detecting the number of peaks and troughs for which it is intended. The associated method of parameter estimation is also assessed; for N ≦ 100, the amplitude of a possibly adequate simple harmonic model is estimated well, but the initial value of the phase angle is not. Estimated percentage points for the extended test statistic are tabulated, and some recommendations are offered regarding usage of this method.     

Systematics,conservation and sustainable development

The contribution of systematics to conservation and sustainable use of species is discussed. An adequate inventory of species is required for both areas and recent field work shows that the inventory is far from complete. This supports the first mission of Agenda 2000 which is to discover described and inventory global species diversity. The importance of making these data available in data base format is stressed. Sound systematics is a necessity for conservation legislation where control depends on the ability to identify organisms correctly. The establishment of reserves is also dependent upon data from systematics about centres of diversity and endemism and examples of this are given. Molecular systematics has made new tools available to conservation such as genetic fingerprinting which is useful both to breeding programmes of rare species and for identification for legal proceedings.Systematics is also one of the foundations for programmes of sustainable development especially in the search for new crops, non-timber forest plants from extraction forests and the identification of wild relatives of crop species. Examples of the role of systematics in a fuelwood programme in Zimbabwe, a sustainable development programme in northeast Brazil and in the search for a chemical component with medicinal properties for curing AIDS are given. The more predictive a classification we can develop using modern cladistic and molecular techniques the more useful systematics will be for both conservation and sustainable development. The goal of Agenda 2000 to organize the information derived from the programme in an efficiently retrievable form that best meets the needs of science and society is a laudable target that is crucial for conservation and the sustainable use of the plant resources of the world.     

Voltage clamp calculations for myelinated and demyelinated axons

Exact cable theory is used to calculate voltage distributions along fully myelinated axons and those with various patterns of demyelination. The model employed uses an R-C circuit for the soma, an equivalent cable for the dendrites, a myelinated axon with n internodes and a cable representing telodendria. For the case of a voltage clamp at the soma, a system of 2n + 1 equations must be solved to obtain the potential distribution and this is done for arbitrary n. An explicit calculation is performed for one internode whereas computer-generated solutions are obtained for several internodes. The relative importance of the position of a single demyelinated internode is determined. An approximate expression is given for the critical internodal length necessary for action potential generation.     

演化极端结合分支分类方法

从生物演化的逆方向考虑,提出一种聚合的分支分类运算方法,称为演化极端结合分支分类法。文章阐明其设计思路、演算步骤,并以实例具体说明其演算过程。最后以演化长度系数、合理解与合理方法等概念,对演化极端结合法进行评价。     

Formation of a stable RuvA protein double tetramer is required for efficient branch migration in vitro and for replication fork reversal in vivo

In bacteria, RuvABC is required for the resolution of Holliday junctions (HJ) made during homologous recombination. The RuvAB complex catalyzes HJ branch migration and replication fork reversal (RFR). During RFR, a stalled fork is reversed to form a HJ adjacent to a DNA double strand end, a reaction that requires RuvAB in certain Escherichia coli replication mutants. The exact structure of active RuvAB complexes remains elusive as it is still unknown whether one or two tetramers of RuvA support RuvB during branch migration and during RFR. We designed an E. coli RuvA mutant, RuvA2(KaP), specifically impaired for RuvA tetramer-tetramer interactions. As expected, the mutant protein is impaired for complex II (two tetramers) formation on HJs, although the binding efficiency of complex I (a single tetramer) is as wild type. We show that although RuvA complex II formation is required for efficient HJ branch migration in vitro, RuvA2(KaP) is fully active for homologous recombination in vivo. RuvA2(KaP) is also deficient at forming complex II on synthetic replication forks, and the binding affinity of RuvA2(KaP) for forks is decreased compared with wild type. Accordingly, RuvA2(KaP) is inefficient at processing forks in vitro and in vivo. These data indicate that RuvA2(KaP) is a separation-of-function mutant, capable of homologous recombination but impaired for RFR. RuvA2(KaP) is defective for stimulation of RuvB activity and stability of HJ·RuvA·RuvB tripartite complexes. This work demonstrates that the need for RuvA tetramer-tetramer interactions for full RuvAB activity in vitro causes specifically an RFR defect in vivo.     

2008, a year for plants to celebrate

2008 is a special year for the Botanical Society of China (BSC)for two reasons. The first one is for the 75th anniversary of the Society, and the second one is for Prof. Zhengyi Wu who received The State Supreme Science and Technology Award,the country's highest science honor. This special issue, with a collection of 16 articles, is dedicated to these events.     

Interval Estimation for Ratios in Bioequivalence Trials

The problem for assessment of equivalence in variability of bioavailability between two drug products is considered. An exact confidence region for the ratio between intrasubject variabilities is derived when the intersubject variance is known. When the intersubject variance is unknown, a large sample approximation is considered. The proposed method for assessing equivalence in variability of bioavailability appears to be asymptotically uncorrelated with the sample mean ratio for average bioavailabilty. As a result, the proposed method in conjunction with the sample mean ratio method can be utilized for assessing population bioequivalence. An example concerning a bioequivalence trial with 24 healthy volunteers is presented to illustrate the proposed method.