Library purchasing consortia in the UK

The distribution of library purchasing consortia across the United Kingdom is uneven and sector-dependent. Only higher education libraries show a well developed regional infrastructure of purchasing consortia covering virtually all eligible libraries. While there are clear sectoral disparities amongst the library purchasing consortia surveyed, the size of consortium expenditure seems to determine whether procurement professionals are involved. Thus in those whose spend consistently exceeds European Commission guidelines’ thresholds, the involvement of purchasing professionals is much more likely, and also crucial to the successful navigation of such procedures

Joining of Immunoglobulin Heavy Chain Gene Segments: Implications from a Chromosome with Evidence of Three D-JH Fusions

A chromosomal segment with a unique structure around the immunoglobulin heavy chain joining region (JH) has been molecularly cloned from an Abelson murine leukemia virus-transformed cell line. Attached to JH3 in the cloned DNA, in inverted sequence, is the DNA from JH1 to the JH2 recognition sequence. The inverted segment is attached at its other end to the 5' recognition sequence of a diversity segment (D). To form this structure, three joining events must have occurred on the same chromosome. One of these events could have been a normal D-JH joining but the others must have been irregular events including ones that result in inversions. One of the joining events left fused recognition elements from JH2 and a D whose sequence shows that, during joining, reciprocal joinings of the recognition elements must occur to fuse the heptameric elements back to back. Because joined D and JH undergo deletion of terminal coding sequence during recombination but the joined heptameric recognition sequences do not contain the deleted sequence, joining must be a nonreciprocal event. Also, extra nucleotides are inserted between D and JH as part of the joining process; it is suggested that this added sequence is a product of the activity of terminal deoxynucleotidyltransferase at the D/JH (and probably the VH/D) joints and that it represents a new element of heavy chain gene structure, the N region

STEM CELL GROWTH AND DIFFERENTIATION IN HYDRA ATTENUATA

The differentiation of nerve cells and nematocytes from interstitial stem cells in Hydra has been investigated under conditions of changing stem cell density. Interstitial stem cells were cultured in a feeder layer system consisting of aggregates of nitrogen mustard-inactivated tissue. The aggregates were seeded with varying numbers of stem cells from 10 to 400 per aggregate; between 4 and 7 days later the rates of nerve and nematocyte differentiation were measured. Nerve differentiation was scored by labelling the stem cell population with [3H]-thymidine and counting nests of 4 proliferating nematoblasts. In both cases the numbers of differentiating cells were normalized to the size of the stem cell population. The results indicate that the rate of nematocyte differentiation increases as the concentration of stem cells increases in aggregates; under the same conditions the rate of nerve differentiation remains essentially constant. To calculate the numbers of stem cells entering each pathway per generation, a computer was programmed to simulate the growth and differentiation of interstitial stem cells. Standard curves were prepared from the simulations relating the rates of nerve and nematocyte differentiation to the fraction of stem cells committed to each pathway per generation. The rates of nerve and nematocyte commitment were then estimated from the experimentally observed rates of differentiation using the standard curves. The results indicate that nerve commitment remains constant at about 0.13 stem cells per generation over a wide range of stem cell concentration. Nematocyte commitment, by comparison, increases from 0.15 to 0.21 stem cells per generation as stem cell concentration increases in aggregates. The fact that the ratio of nerve to nematocyte commitment changes under our conditions suggests that stem cell commitment is not a stochastic process but subject to control by environmental stimuli

Cultural Intelligence Growth of Guatemala Internship Participants

Like many other forms of knowledge, cultural intelligence (CQ) is acquired or learned. Our study uses the CQ scale as a means of measuring growth in cultural intelligence in students participating in a two-month home-stay in Guatemala. Based on this data, we selected students to interview as a way of discovering specifically in what areas they grew the most and why they think they experienced CQ growth. As a result of these interviews, we have pinpointed three key areas of growth that will be the focus of this post presentation: a shift from extrinsic to intrinsic motivation, a rejection of stereotype-based knowledge of culture, and linguistic growth that empowers students to engage culture

Studies of Birds and Mammals in the Baird and Schwatka Mountains, Alaska

In 1963 a joint University of Alaska-Smithsonian Institution crew worked at five locations in the Baird and Schwatka mountains in northwestern Alaska, conducting an ecological reconnaissance and faunal and floral inventory. Standard methods of observation and collection were used. Camps in the Kobuk drainage were located in the Redstone River valley and at Walker Lake, both on the margin of the taiga. The Noatak valley was represented by one camp each in the lower, middle, and upper reaches of the river, all in tundra. A summary of pre-1963 ornithological work in the region is presented. Significant records of distribution and/or breeding were obtained for the following birds: Podiceps grisegena, Anas platyrhynchos, Aythya valisineria, Histrionicus histrionicus, Melanitta perspicillata, Mergus merganser, Aphrizia virgata, Bartramia longicauda, Actitis macularia, Tringa flavipes, Phalaropus fuficarius, Lobipes lobatus, Larus hyperboreus,Xema sabini, Sayornis saya, Nuttalornis borealis, Eremophilia alpestris, Tachycineta thalassina, Riparia riparia, Petrochelidon pyrrhonota, Phylloscopus borealis, Dendroica petechia, Leucosticte tephrocotis, Zonotrichia atricapilla, Calcarius pictus; and the mammal, Spermophilus undulatus. Good series of Cletihrionomys rutilius (350) and Microtus miurus (147) have been deposited in the University of Alaska Museum. Severe doubt has been raised regarding the validity of the standard three-night trap grid for population estimation under wet conditions in arctic areas

The mean and variance of phylogenetic diversity under rarefaction

Phylogenetic diversity (PD) depends on sampling intensity, which complicates the comparison of PD between samples of different depth. One approach to dealing with differing sample depth for a given diversity statistic is to rarefy, which means to take a random subset of a given size of the original sample. Exact analytical formulae for the mean and variance of species richness under rarefaction have existed for some time but no such solution exists for PD. We have derived exact formulae for the mean and variance of PD under rarefaction. We show that these formulae are correct by comparing exact solution mean and variance to that calculated by repeated random (Monte Carlo) subsampling of a dataset of stem counts of woody shrubs of Toohey Forest, Queensland, Australia. We also demonstrate the application of the method using two examples: identifying hotspots of mammalian diversity in Australasian ecoregions, and characterising the human vaginal microbiome. There is a very high degree of correspondence between the analytical and random subsampling methods for calculating mean and variance of PD under rarefaction, although the Monte Carlo method requires a large number of random draws to converge on the exact solution for the variance. Rarefaction of mammalian PD of ecoregions in Australasia to a common standard of 25 species reveals very different rank orderings of ecoregions, indicating quite different hotspots of diversity than those obtained for unrarefied PD. The application of these methods to the vaginal microbiome shows that a classical score used to quantify bacterial vaginosis is correlated with the shape of the rarefaction curve. The analytical formulae for the mean and variance of PD under rarefaction are both exact and more efficient than repeated subsampling. Rarefaction of PD allows for many applications where comparisons of samples of different depth is required.Comment: Final version to be published in Methods in Ecology and Evolutio

Photonic and hardonic interactions

Imperial Users onl

The taxonomic significance of the anatomy of the Restionaceae

Imperial Users onl