VLT FORS spectra of blue supergiants in the Local Group galaxy NGC 6822

Half hour exposures using the ESO VLT/FORS1 combination at Paranal in Chile have allowed us to obtain spectra for three B supergiants in the dwarf irregular galaxy NGC 6822. The spectra have been analysed using non-LTE techniques and temperatures, gravities, helium content and abundances have been obtained. Overall the metallicity of NGC 6822 is found to lie between that of the LMC and of the SMC, in agreement with previous observations of H II regions and in contrast to the earlier findings of Massey et al. (1995). The analysis of H-alpha yields estimates of the mass-loss rates and wind momenta. These results demonstrate that significantly longer exposures with the same instruments will allow us to perform quantitative spectroscopy of blue supergiants in galaxies far beyond the Local Group.

Racism and young girls' peer group relations: the experiences of South Asian girls

This article draws upon data from an indepth ethnographic study of five- and six-year-old children in an English multi-ethnic, inner city primary school. It focuses on the significance of ‘race’ within young girls’ peer group relations and the ways in which the social dynamics that underlie those relations provide the context for understanding the particular nature and form that racism takes among the girls. This is done through a focus on the experiences of South Asian girls within the group. Within this, the article has two main aims. First, it aims to contribute to the literature within the sociology of education by extending the existing research focus on racism within teacher/pupil interactions to include an understanding of racism as it manifests itself among the children’s peer-group relations. Second, in adapting and applying Pierre Boudieu’s concepts of capital and field, the article also offers a contribution to the literature within the sociology of ‘race’ and ethnicity by suggesting one potentially fruitful way in which racism can be understood within specific social contexts.

Racism, masculine peer-group relations and the schooling of African/Caribbean infant boys

The past decade has witnessed the publication of a growing number of important ethnographic studies investigating the schooling experiences of Black students. Their focus has largely been upon student-teacher relations during the students' last few years of compulsory schooling. What they have highlighted is the complexity of racism and the varied nature of Black students' experiences of schooling. Drawing upon data from a year-long ethnographic study of an inner-city, multi-ethnic primary school, this paper aims to compliment these studies in two ways. Firstly the paper will broaden the focus to examine how student peer-group relations play an integral role, within the context of student-teacher relations, in shaping many Black students' schooling experiences. By focussing on African/Caribbean infant boys, it will be shown how student-teacher relations on the one hand, and peer-group relations on the other, form a continuous feed-back loop; the products of each tending to exacerbate and inflate the other. Secondly, by concentrating on infant children, the paper will assess the extent to which these resultant processes and practices are also evident for Black pupils at the beginning of their school careers - at the ages of five and six.

Genetic analysis of the O-specific lipopolysaccharide biosynthesis region (rfb) of Escherichia coli K-12 W3110:identification of genes that confer group 6 specificity to Shigella flexneri serotypes Y and 4a

We recently reported a novel genetic locus located in the sbcB-his region of the chromosomal map of Escherichia coli K-12 which directs the expression of group 6-positive phenotype in Shigella flexneri lipopolysaccharide, presumably due to the transfer of O-acetyl groups onto rhamnose residues of the S. flexneri O-specific polysaccharide (Z. Yao, H. Liu, and M. A. Valvano, J. Bacteriol. 174:7500-7508, 1992). In this study, we identified the genetic region encoding group 6 specificity as part of the rfb gene cluster of E. coli K-12 strain W3110 and established the DNA sequence of most of this cluster. The rfbBDACX block of genes, located in the upstream region of the rfb cluster, was found to be strongly conserved in comparison with the corresponding region in Shigella dysenteriae type 1 and Salmonella enterica. Six other genes, four of which were shown to be essential for the expression of group 6 reactivity in S. flexneri serotypes Y and 4a, were identified downstream of rfbX. One of the remaining two genes showed similarities with rfc (O-antigen polymerase) of S. enterica serovar typhimurium, whereas the other, located in the downstream end of the cluster next to gnd (gluconate-6-phosphate dehydrogenase), had an IS5 insertion. Recently, it has been reported that the IS5 insertion mutation (rfb-50) can be complemented, resulting in the formation of O16-specific polysaccharide by E. coli K-12 (D. Liu and P. R. Reeves, Microbiology 140:49-57, 1994). We present immunochemical evidence suggesting that S. flexneri rfb genes also complement the rfb-50 mutation; in the presence of rfb genes of E. coli K-12, S. flexneri isolates express O16-specific polysaccharide which is also acetylated in its rhamnose residues, thereby eliciting group 6 specificity.

C∗-Segal algebras with order unit

We introduce the notion of a (noncommutative) C *-Segal algebra as a Banach algebra (A, {norm of matrix}{dot operator}{norm of matrix} A) which is a dense ideal in a C *-algebra (C, {norm of matrix}{dot operator}{norm of matrix} C), where {norm of matrix}{dot operator}{norm of matrix} A is strictly stronger than {norm of matrix}{dot operator}{norm of matrix} C onA. Several basic properties are investigated and, with the aid of the theory of multiplier modules, the structure of C *-Segal algebras with order unit is determined.

Strategic development in exact calculation: Group and individual differences in four achievement subtypes

This longitudinal study sought to identify developmental changes
in strategy use between 5 and 7 years of age when solving exact
calculation problems. Four mathematics and reading achievement
subtypes were examined at four time points. Five strategies were
considered: finger counting, verbal counting, delayed retrieval,
automatic retrieval, and derived fact retrieval. Results provided
unique insights into children’s strategic development in exact calculation
at this early stage. Group analysis revealed relationships
between mathematical and/or reading difficulties and strategy
choice, shift, and adaptiveness. Use of derived fact retrieval by
7 years of age distinguished children with mathematical difficulties
from other achievement subtypes. Analysis of individual differences
revealed marked heterogeneity within all subtypes,
suggesting (inter alia) no marked qualitative distinction between
our two mathematical difficulty subtypes.

Animal group forces resulting from predator avoidance and competition minimization

A new model to explain animal spacing, based on a trade-off between foraging efficiency and predation risk, is derived from biological principles. The model is able to explain not only the general tendency for animal groups to form, but some of the attributes of real groups. These include the independence of mean animal spacing from group population, the observed variation of animal spacing with resource availability and also with the probability of predation, and the decline in group stability with group size. The appearance of "neutral zones" within which animals are not motivated to adjust their relative positions is also explained. The model assumes that animals try to minimize a cost potential combining the loss of intake rate due to foraging interference and the risk from exposure to predators. The cost potential describes a hypothetical field giving rise to apparent attractive and repulsive forces between animals. Biologically based functions are given for the decline in interference cost and increase in the cost of predation risk with increasing animal separation. Predation risk is calculated from the probabilities of predator attack and predator detection as they vary with distance. Using example functions for these probabilities and foraging interference, we calculate the minimum cost potential for regular lattice arrangements of animals before generalizing to finite-sized groups and random arrangements of animals, showing optimal geometries in each case and describing how potentials vary with animal spacing. (C) 1999 Academic Press.</p>

Health Awareness Drama by the Mavumbo Youth Group, Mongu Western Zambia, the Trickle Out Project

Video from fieldwork research in Zambia

Low prevalence of primary biliary cirrhosis in Victoria, Australia. Melbourne Liver Group

A prevalence study of primary biliary cirrhosis was carried out in the state of Victoria, Australia, by means of a mail survey of specialist physicians and a review of hospital records. Eighty four cases were identified, giving a prevalence of 19.1 per million population (95% confidence limits (CI) 15.3, 23.7), which is among the lowest in published reports. The prevalence in the Australian born, at risk population (women over the age of 24) was 51 per million (95% CI 37.5, 67.9). Both these figures are considerably lower than those in populations of similar age distribution in the UK and northern Europe. Since most Victorians are descended from British or European settlers, the low prevalence of primary biliary cirrhosis in this study supports the hypothesis that local environmental factors may be important in the pathogenesis of this disease.