Ecological notes of the alien species Godiva quadricolor (Gastropoda: Nudibranchia) occurring in Faro Lake (Italy)

The first record from Sicily of the introduced facelinid nudibranch Godiva quadricolor allowed the detection of trophic relationships with the polycerid Polycera hedgpethi, another non-native nudibranch, and with two bryozoan species, namely the naturalized Cheilostomatida Bugula neritina and the cryptogenic Ctenostomatida Amathia verticillata. The settlement of both nudibranchs was presumably promoted by a trophic shift of P. hedgpethi from the natural prey B. neritina towards the largely available and not exploited A. verticillata. This short food web, without evident links with native fauna and having G. quadricolor as the top predator, is described. A DNA barcoding approach was used to confirm the identity of this facelinid species and to explore the possible genetic divergence occurring among the samples analysed.     

张量广义特征值的S-型包含区域

设{A,B}为m阶n维正则张量对,通过将指标集N={1,2,…,n}划分为非空真子集S及其补集S珚=N/S,利用分类讨论的思想以及张量对{A,B}某些元素选取的任意性和不等式缩放技巧,解决了张量对{A,B}的特征值定位问题,并给出张量对{A,B}特征值的S-型包含区域.数值结果表明,所得包含区域比已有包含区域更精确.     

正规矩阵特征值扰动的新估计

设A,B均为正规矩阵,关于正规矩阵的特征值扰动,有结论 (n∑i=1︱μτ(i)-λi︱2)(1/2)≤n(1/2)‖E‖F,其中λi,μi分别为A,B的特征值.通过新的方法证明给出特征值扰动上界的新估计,并改进了以上结论.     

计算最小特征值的幂法及一个应用

证明Euler幂法程序的收敛性,并用来计算一个复杂的带偶合边条件的微分方程特征值问题的最小特征值。     

Using an Action Research Framework to Explore Assessment: A South African Case Study

This article is a reflection of my first experience with action research in trying to devise a system of assessment that would benefit both first and second language speakers of English in an assessment system that is plagued by its separatist past. In this paper, I discuss an action research study on oral assessment implemented at two tertiary institutions in South Africa. The actual details of each phase of the assessments are not reported on, but the methods used to facilitate the processes are. The findings and adaptations after each phase of the assessments are discussed to show the effectiveness of using an action research methodology.

结构动力分析中Kuhar方法的改进和收敛性

本文介绍了结构动力分析中基于Ｋｕｈａｒ方法的动力缩减迭代法，应用矩阵摄动理论证明了其收敛性，算例说明了方法的有效性     

关于一个非线性椭圆特征问题的某些注记

讨论一个非线性椭圆特征问题，减弱了原有结果中的一个条件而得到同样的结果，并讨论了参数小于λ１的情形。     

Szász-Mirakyan算子对不连续函数的逼近研究

研究用szász-Mirakyan算子S_n(f, x)逼近在(0,+∞)上具有第一类间断点的有界函数了,给出了收敛速度的估计。     

首达渗流中关于时间常数μ的上界估计

对2维首达渗流的时间常数μ给出了一个上界估计．     

弹性梁静态方程的可解性

给出滑动支撑的弹性梁静态方程可解的一组两参数非共振条件.