Clones identification of Sequoia sempervirens (D. Don) Endl. in Chile by using PCR-RAPDs technique

A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied. The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction. The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index and a dendrogram was constructed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA). Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of 49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although they are derived from the same geographic origin. Project (No. CONICYT-FONDEF PROYECT D01 I 1008) supported by the National Commission of Science and Research of Chile     

我国体育用品业未来发展走向初探

通过对我国体育用品市场需求量,以及体育用品业存在的问题和面临的挑战的分析,认为产业升级是我国体育用品业未来发展的主要走向.     

Indicators of sailing performance in youth dinghy sailing

Abstract

This study aimed to determine indicators of sailing performance in 2 (age) groups of youth sailors by investigating the anthropometric, physical and motor coordination differences and factors discriminating between elite and non-elite male optimist sailors and young dynamic hikers. Anthropometric measurements from 23 optimist sailors (mean ± SD age = 12.3 ± 1.4 years) and 24 dynamic youth hikers (i.e. Laser 4.7, Laser radial and Europe sailors <18 years who have to sail the boat in a very dynamic manner, due to a high sailor to yacht weight ratio) (mean ± SD age = 16.5 ± 1.6 years) were conducted. They performed a physical fitness test battery (EUROFIT), motor coordination test battery (Körperkoordinationstest für Kinder) and the Bucket test. Both groups of sailors were divided into two subgroups (i.e. elites and non-elites) based on sailing expertise. The significant differences, taking biological maturation into account and factors discriminating between elite and non-elite optimist sailors and dynamic hikers were explored by means of multivariate analysis of covariance and discriminant analysis, respectively. The main results indicated that 100.0% of elite optimist sailors and 88.9% of elite dynamic hikers could be correctly classified by means of two motor coordination tests (i.e. side step and side jump) and Bucket test, respectively. As such, strength- and speed-oriented motor coordination and isometric knee-extension strength endurance can be identified as indicators of sailing performance in young optimist and dynamic youth sailors, respectively. Therefore, we emphasise the importance of motor coordination skill training in optimist sailors (<15 years) and maximum strength training later on (>15 years) in order to increase their isometric knee-extension strength endurance.     

技能类运动竞赛裁判员评分合理性评价方法研究

本研究依据定量的评价方法，对技能类运动竞赛裁判员在执行裁判中主观评分的公正性、合理性进行优劣排序评价，以期裁判员在执行裁判中进一步做到公正、准确。     

注重物理科学方法教育,培养学生创造能力

物理科学方法教育有利于学生能力的培养,科学世界观的形成,以及对物理知识的掌握和对物理规律的认识。而物理科学方法教育要以物理实验为基础,结合物理概念、规律和物理学史进行方法教育。     

Modelling and analysis of a basilica under earthquake loading

In this paper a basilica-type church is analysed in order to assess its structural behaviour and seismic vulnerability. For this purpose, an effective two-step procedure has been used, consisting of: (a) 3D static and dynamic linear analyses of the structural complex, and (b) 2D nonlinear push-over analysis of the single macro-elements. The results obtained through push-over analyses have been compared to the collapse loads derived from limit analysis, proving the ability of finite element (F.E.) nonlinear model to provide reliable simulation of the actual response of masonry elements. Then, the strength demand on each single structural macro-elements, resulting from the 3D linear analyses, has been compared to the macro-element ultimate strength capacity. The comparison demand vs. capacity has been carried out for all transversal and longitudinal macro-elements of the church, allowing a direct, though approximate, assessment of the seismic safety level of the church. The comparison demand vs. capacity confirms the susceptibility of this type of buildings to extensive damage and possibly to collapse, as frequently observed. The insertion of rigid diaphragms, which represents a widely used retrofit technique, has also been investigated; such intervention triggers concentration of strength demand in the stiffest macro-elements, so that the seismic capacity of the building is not necessarily increased.     

The Socio-Economic Background of Erasmus Students: A Trend Towards Wider Inclusion?

The article focuses on the financial issues and family background of Erasmus students. It examines the costs of Erasmus study periods in the academic year 2004/05 and the socio-economic background of Erasmus students that year, based on over 15000 survey responses. Results are compared with those of a similar survey undertaken in 1998 to track changes over the last decade. The main question that the article addresses is whether international mobility of higher education students within the Erasmus programme has been expanded to more students from lower socio-economic backgrounds during this period. We find that, in spite of still important socio-economic barriers to the take-up of the programme, access has been moderately widened.