INTERNATIONAL TRADE: HOW IT AFFECTS VIRGINIA AGRICULTURE

International Relations/Trade,

The Scottish comprehensive school: it’s function and the roles of its teachers, with special reference to the opinions of pupils and student-teachers

The research compared the views of a sample of Scottish comprehensive-school pupils and, a sample of students training to become secondary-school teachers in two Scottish Colleges of Education on the two subjects: "The Characteristics of a Good Teacher" and "The Purpose of School". Essays on the two topics were collected from a sample of pupils in three comprehensive schools in central Scotland. The essays were unitized into statements, and two category-systems were developed to code them. Statements on both topics were also obtained from a small sample of student-teachers to ensure that the universe of statements derived from the essays was truly exhaustive. The statements made most frequently by pupils were included in a two-part questionnaire; care was taken to ensure that the views of all the sub-groups of the pupil sample were properly represented. The questionnaire was administered to a sample of pupils and student-teachers. The method of completion was devised by the researcher to facilitate the selection of a small group of statements to be ranked from an initially large number of statements. This process involved progressive stages of elimination by means of "collapsing" four lists of statements to form two, and finally one. Six alternative forms of the questionnaire were constructed, to avoid bias arising from the statements' order of presentation. The four lists on both sections of the questionnaire were also balanced by the seeding of statements across the lists according to their estimated appeal to respondents, and by the equal distribution of statements referring to particular areas, (eg. the teacher's discipline).The results revealed major disagreement between students' and pupils' views on the purpose of school, but closer agreement on the characteristics of a good teacher

Bridging, brokerage and betweenness

Valente and Fujimoto (2010) proposed a measure of brokerage in networks based on Granovetter’s classic work on the strength of weak ties. Their paper identified the need for finding node-based measures of brokerage that consider the entire network structure, not just a node’s local environment. The measures they propose, aggregating the average change in cohesion for a node’s links, has several limitations. In this paper we review their method and show how the idea can be modified by using betweenness centrality as an underpinning concept. We explore the properties of the new method and provide point, normalized, and network level variations. This new approach has two advantages, first it provides a more robust means to normalize the measure to control for network size, and second, the modified measure is computationally less demanding making it applicable to larger networks

cDNA-RNA subtractive hybridization reveals increased expression of mycocerosic acid synthase in intracellular Mycobacterium bovis BCG.

Identifying genes that are differentially expressed by Mycobacterium bovis BCG after phagocytosis by macrophages will facilitate the understanding of the molecular mechanisms of host cell-intracellular pathogen interactions. To identify such genes a cDNA-total RNA subtractive hybridization strategy has been used that circumvents the problems both of limited availability of bacterial RNA from models of infection and the high rRNA backgrounds in total bacterial RNA. The subtraction products were used to screen a high-density gridded Mycobacterium tuberculosis genomic library. Sequence data were obtained from 19 differential clones, five of which contained overlapping sequences for the gene encoding mycocerosic acid synthase (mas). Mas is an enzyme involved in the synthesis of multi-methylated long-chain fatty acids that are part of phthiocerol dimycocerosate, a major component of the complex mycobacterial cell wall. Northern blotting and primer extension data confirmed up-regulation of mas in intracellular mycobacteria and also revealed a putative extended -10 promoter structure and a long untranslated upstream region 5' of the mas transcripts, containing predicted double-stranded structures. Furthermore, clones containing overlapping sequences for furB, groEL-2, rplE and fadD28 were identified and the up-regulation of these genes was confirmed by Northern blot analysis. The cDNA-RNA subtractive hybridization enrichment and high density gridded library screening, combined with selective extraction of bacterial mRNA represents a valuable approach to the identification of genes expressed during intra-macrophage residence for bacteria such as M. bovis BCG and the pathogenic mycobacterium, M. tuberculosis