Variation and phylogeny of the triploid cultivated potatoSolanum chaucha Juz. et Buk. based on RAPD and isozyme markers

Ninety four accessions of the cultivated triploid potatoS. chaucha were analyzed and classified in genotypic groups using 9 isozyme loci and RAPD markers disclosed by 20 arbitrary 10-mer primers. Eight isozyme loci out of nine were polymorphic. A total of 22 allozymes were analyzed but none of them were specific for any genotypic group. About half (52%) of the 102 RAPD markers scored, were polymorphic, all of them showing polymorphism among groups and rarely within groups. Eighteen RAPD markers were specific for certain genotypes. The isozyme markers showed a certain amount of intra group variation which made classification less reliable than with RAPD markers. A total of 10 triploid genetic groups were discriminated using both techniques together. A single primer was found to be sufficient to distinguish all 10 groups. All varieties of a single group are considered to have been derived from the same cross and then clonally propagated, even though there is a high amount of morphological variation within a single genotypic group due probably to somatic mutations. RAPD markers have been shown to be more reliable in the classification of triploid potato varieties than other genetic markers like isozymes, proteins and morphological traits.     

Biomass limit reference points are sensitive to estimation method,time‐series length and stock development

Biomass limit reference points are widely used in fisheries management and define the biomass threshold (BT) below which stock productivity (i.e. recruitment) is likely to be impaired. Scientifically sound and transparent methods for estimating BTs are therefore needed together with ways of quantifying uncertainties. The main focus of the study was placed on two methods currently applied to several small‐bodied pelagic species in the Northeast Atlantic. These methods have not formerly been described in the scientific literature and are in the present study being compared with some already described methods, of which one is broadly applied outside the Northeast Atlantic. Using a combination of data simulations and data from 51 small‐bodied pelagic fish stocks, we analysed the sensitivity of estimated BTs to (a) the choice of method, (b) time‐series length and (c) stock development (e.g. rebuilding or declining). It was demonstrated that estimated BTs are associated with considerable uncertainty not previously quantified. Furthermore, the level of the estimated threshold and the amount of uncertainty depended on choice of method, time‐series length and stock development trends. Hence, this study contributes to improving the quality of future biomass limit reference points by providing guidance regarding choice of method and how to demonstrate stock‐specific uncertainties.     

电磁波在组合介质中传播的二维数值计算

利用时域有限差分法（FDTD）对电磁波在大气等离子体、吸波材料和金属层组合介质中传播进行二维的数值模拟。讨论了电磁波的入射角与极化模式之间的关系以及其对反射率的影响,分析了等离子体电子密度分布、等离子体层和吸波层厚度等几个重要参数对组合材料衰减特性的影响,为提高组合材料对电磁波的衰减性能提供了理论依据。     

双端口RAM及其在CAN总线适配卡中的实现

针对CAN总线要实现高速数据交换的要求，要实现PC机与CAN总线之间的数据传送，双端口RAM就要在PC机和适配卡之间建立双向的数据交换通道。本文主要介绍双端口RAM的特点，功能及硬件判优工作方式在CAN总线适配卡中的应用。     

Estimating stock depletion level from patterns of catch history

The degree to which a stock is depleted is one of the most important quantities in fisheries management because it is used to quantify the success of management and to inform management responses. However, stock depletion is extremely difficult to estimate, particularly with limited data. Using the RAM Legacy database, we developed a boosted regression tree (BRT) model to correlate depletion with a range of predictors calculated from catch data, making the model usable for many fisheries worldwide. The most important predictors were found to be catch trends obtained from linear regressions of scaled catch on time, including regression coefficients for the whole catch time series, the subseries before and after the maximum catch, and in recent years. Eight predictors explain about 80% of variation in depletion. There is a correlation of .5 between measured levels of depletion and the predictions of the BRT model. Predictions are less biased when the stock is fished down below half of the carrying capacity. The BRT model outperforms comparable existing catch‐based depletion estimators and could be used to provide priors for depletion for data‐poor stock assessment methods, or used more directly to provide estimates of the probability that depletion is below a given threshold value.     

微机可读写电子磁盘的设计与实现

介绍了一种多功能可读写电子仿真磁盘，它不仅可以替代传统磁盘及驱动器，还可以用来固化用户的应用程序，它仍可利用磁盘操作系统软件，而其读写速度，可靠性，结构安装及性能价格比都是传统的磁盘所不能比拟的，它具有３６０ｋＢＲＯＭ和２５６ｋＢ带拌电保护静态ＲＡＭ，实际所占内存空间仅４ｋＢ它特别适用于环境恶劣并要求高可靠性，高存取速度的工业现场实百自动检测及控制方面存储用户程序和数据。     

植物干细胞中WUS/CLV反馈调控机制的研究进展

回顾植物顶端、根端和侧生分生组织的模式结构,以及干细胞区的WUSCHEL/CLAVATA(WUS/CLV)反馈调控机制研究进展发现,3种分生组织不仅都具有长期潜在的维持原始细胞启动状态的功能,而且可能都存在调控相邻干细胞分裂、分化的干细胞区。茎端分生组织中和根端分生组织中分别存在WUS/CLV和WOX5/CLE40反馈调控机制,2种反馈调控机制都具有维持干细胞区的分裂及其与其他组织形成之间的动态平衡功能。而有关植物尤其是木本植物的维管形成层组织中WUS/CLV反馈调控机制的报道不多,文中就这方面的研究进行综述和展望。     

Identifying spawner biomass per‐recruit reference points from life‐history parameters

Analysis of spawning biomass per‐recruit has been widely adopted in fisheries management. Fishing mortality expressed as spawning potential ratio (SPR) often requires a reference point as an appropriate proxy for the fishing mortality that supports a maximum sustainable yield—F_MSY. To date, a single generic level between F_30% and F_40% is routinely used. Using records from stock assessments in the RAM Legacy Database (RAMLD), we confirm that SPR at MSY (SPR_MSY) is a declining function of stock productivity quantified by F_MSY. We then use general linear models (GLM) and Bayesian errors‐in‐variables models (BEIVM) to show that SPR_MSY can be predicted from life‐history parameters (LHPs, including maximum lifespan, age‐ and length‐at‐maturation, growth parameters, natural mortality, and taxonomic Class) as well as gear selectivity. The calculated SPR_MSY ranges from about 13% to 95% with a mean of 47%. About 64% of the stocks in the RAMLD require SPR_MSY > 40%. Modelling SPR_MSY reveals that LHPs plus Class explain 61% of the deviance in SPR_MSY. Faster‐growing, low‐survival, and short‐lived species generally require a high SPR. With equal LHPs, elasmobranchs require about 20% higher SPR_MSY than teleosts. When F_MSY is estimated from fisheries that harvest older fish, increasing the vulnerable age by one year leads to about an 8% increase in SPR_MSY. The BEIVM yields smaller variance and bias than the GLM. The models developed in this study could be used to predict SPR_MSY reference points for new stocks using the same LHPs for calculating F_x%, but without knowledge of the stock‐recruitment parameters.     

一种配变监测终端交流采样及算法方案的确定

本文在一种用于电力系统生产、管理的配变监测终端的设计和研制工作中,对目前常用的各种采样方案和算法进行了分析、比较、筛选,确定了非同步采样和顺序采样的方案;并提出了一种寻找过零点动态计算每周采样点数的提高精度的采样数据处理方法。