4,039 research outputs found

    New diatom taxa from the world’s first marine Bioblitz held in New Zealand: Skeletomastus a new genus, Skeletomastus coelatus nov. comb. and Pleurosigma inscriptura a new species

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    Diatoms were investigated as part of the world’s first marine Bioblitz held on the south coast of Wellington, New Zealand, in October 2007. Two unusual diatoms were associated with the red alga Herposiphonia ceratoclada. They were examined by light and scanning electron microscopy. The first, previously described as »Cocconeis coelata« Arnott ex Greville, is a thick-ribbed biraphid diatom that appears to have an undular raphe and marginal septum like some Mastogloia species, but it does not have partecta in the valvocopula. Instead it has short marginal ribs that support a pseudoseptum. Its solid lyre and multiseriate striae with cibrate pores could be modifications of similar structures in Aneumastus aksaraiensis Spaulding et al. It typifies the new genus Skeletomastus which appears to be close to both Mastogloia and Aneumastus, hence the name. The second is a proposed new Pleurosigma species, P. inscriptura with naviculoid symmetry and a markedly sigmoid raphe system with deflected ends. It appears bright blue in darkfield illumination which helped us locate it in other samples from theWellington region.We compare it with some other Pleurosigma species and consider their diffraction properties

    The anti-chain store movement in the United States, 1927-1940

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    This thesis is intended to provide the first considerable history of the sustained political offensive which was mounted against chain stores in the 'United States between 1927 and 1940. The work falls into five divisions. Part One examines the overall pattern of chain store development during this period and the impact of the changing interpretation and enforcement of the antitrust laws on the "chain store question". Part Two begins the chronological account of the anti-chain movements describing the attempts made by independent merchants, principally in the South and the interior states, to whip up feelings of "home town loyalty" to encourage a popular boycott of chain stores. After 1930s agitation of this character subsided, but the chains were then confronted by a more substantial threats that of discriminatory taxation. The development of the chain store tax weapon up to 1935, in which year the U. S. Supreme Court approved the principle of confiscatory chain store taxation and two states enacted severely repressive measures, is reviewed in Part Three. In 1935-1936 the chains also fell foul of Congress, a complex sequence of events - the subject of Part four - resulting in enactment of the Robinson-Patman price discrimination laws the only substantial legacy of the anti-chain movement. To this points the record was one of ever worsening danger for the chains, but 1936 proved to be the turning of the tide. The levelling off of chain store growth; the general economic upturn; the more relaxed competitive relationship between chains and independents fostered by price maintenance legislation, and the collapse of the broader politics of discontent which had done much to help the cause of the enemies of the chains in the mid-19301ss all served to hasten the demise of the anti-chain movement. Part five relates its remorseless descent to oblivion

    Thermal boundary conditions on western Greenland: Observational constraints and impacts on the modeled thermomechanical state

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    The surface and basal boundary conditions exert an important control on the thermodynamic state of the Greenland Ice Sheet, but their representation in numerical ice sheet models is poorly constrained due to the lack of observations. Here we investigate a land-terminating sector of western Greenland and (1) quantify differences between new observations and commonly used boundary condition data sets and (2) demonstrate the impact of improved boundary conditions on simulated thermodynamics in a higher-order numerical flow model. We constrain near-surface temperature with measurements from two 20mboreholes in the ablation zone and 10m firn temperature from the percolation zone. We constrain basal heat flux using in situ measurement in a deep bedrock hole at the study area margin and other existing assessments. To assess boundary condition influences on simulated thermal-mechanical processes, we compare model output to multiple full-thickness temperature profiles collected in the ablation zone.Our observation-constrained basal heat flux is 30mW m2 less than commonly used representations. In contract, measured near-surface temperatures are warmed than common surface warmer than common surface temperature data sets by up to 15 degrees C. Application of lower basal heat flux increases a model cold bias compared to the measured temperature profiles and causes frozen basal conditions across the ablation zone. Temperate basal conditions are reestablished by our warmer surface boundary. Warmer surface ice and firn can introduce several times more energy to the modeled ice mass than what is lost at the bed from reduced basal heat flux, indicating that the thermomechanical state of the ice sheet is highly sensitive to near-surface effects

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    A QUANTITATIVE METHOD FOR ANALYSING 3-D BRANCHING IN EMBRYONIC KIDNEYS: DEVELOPMENT OF A TECHNIQUE AND PRELIMINARY DATA

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    The normal human adult kidney contains between 300,000 and 1 million nephrons (the functional units of the kidney). Nephrons develop at the tips of the branching ureteric duct, and therefore ureteric duct branching morphogenesis is critical for normal kidney development. Current methods for analysing ureteric branching are mostly qualitative and those quantitative methods that do exist do not account for the 3- dimensional (3D) shape of the ureteric "tree". We have developed a method for measuring the total length of the ureteric tree in 3D. This method is described and preliminary data are presented. The algorithm allows for performing a semi-automatic segmentation of a set of grey level confocal images and an automatic skeletonisation of the resulting binary object. Measurements of length are automatically obtained, and numbers of branch points are manually counted. The final representation can be reconstructed by means of 3D volume rendering software, providing a fully rotating 3D perspective of the skeletonised tree, making it possible to identify and accurately measure branch lengths. Preliminary data shows the total length estimates obtained with the technique to be highly reproducible. Repeat estimates of total tree length vary by just 1-2%. We will now use this technique to further define the growth of the ureteric tree in vitro, under both normal culture conditions, and in the presence of various levels of specific molecules suspected of regulating ureteric growth. The data obtained will provide fundamental information on the development of renal architecture, as well as the regulation of nephron number

    Calcium-Dependent Protein Kinases from Arabidopsis Show Substrate Specificity Differences in an Analysis of 103 Substrates

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    The identification of substrates represents a critical challenge for understanding any protein kinase-based signal transduction pathway. In Arabidopsis, there are more than 1000 different protein kinases, 34 of which belong to a family of Ca2+-dependent protein kinases (CPKs). While CPKs are implicated in regulating diverse aspects of plant biology, from ion transport to transcription, relatively little is known about isoform-specific differences in substrate specificity, or the number of phosphorylation targets. Here, in vitro kinase assays were used to compare phosphorylation targets of four CPKs from Arabidopsis (CPK1, 10, 16, and 34). Significant differences in substrate specificity for each kinase were revealed by assays using 103 different substrates. For example CPK16 phosphorylated Serine 109 in a peptide from the stress-regulated protein, Di19-2 with KM ∌70 ΌM, but this site was not phosphorylated significantly by CPKs 1, 10, or 34. In contrast, CPKs 1, 10, and 34 phosphorylated 93 other peptide substrates not recognized by CPK16. Examples of substrate specificity differences among all four CPKs were verified by kinetic analyses. To test the correlation between in vivo phosphorylation events and in vitro kinase activities, assays were performed with 274 synthetic peptides that contained phosphorylation sites previously mapped in proteins isolated from plants (in vivo-mapped sites). Of these, 74 (27%) were found to be phosphorylated by at least one of the four CPKs tested. This 27% success rate validates a robust strategy for linking the activities of specific kinases, such as CPKs, to the thousands of in planta phosphorylation sites that are being uncovered by emerging technologies
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