9,008 research outputs found

    Renewable Energy Resources Impact on Clean Electrical Power by developing the North-West England Hydro Resource Model.

    Get PDF
    This paper describes the development of a sequential decision support system to promote hydroelectric power in North-West England. The system, composed of integrated models, addresses barriers to the installation of hydroelectric power schemes. Information is linked through an economic assessment which identifies different turbine options, assesses their suitability for location and demand; and combines the different types of information in a way that supports decision making. The system is structured into five components: the hydrological resource is modelled using Low Flows 2000, the turbine options are identified from hydrological, environmental and demand requirements; and the consequences of different solutions will be fed into other components so that the environmental impacts and public acceptability can be assessed and valued. A preliminary case study is presented on an old gunpowder works to illustrate how the resource model may be employed. Historical architectural structures, power uptake and educational instruction of hydro power technology are considered

    Intracellular immunohistochemical detection of tetrodotoxin in Pleurobranchaea maculata (Gastropoda) and Stylochoplana sp. (Turbellaria)

    Get PDF
    Tetrodotoxin (TTX), is a potent neurotoxin targeting sodium channels that has been identified in multiple marine and terrestrial organisms. It was recently detected in the Opisthobranch Pleurobranchaea maculata and a Platyhelminthes Stylochoplana sp. from New Zealand. Knowledge on the distribution of TTX within these organisms is important to assist in elucidating the origin and ecological role of this toxin. Intracellular micro-distribution of TTX was investigated using a monoclonal antibody-based immunoenzymatic technique. Tetrodotoxin was strongly localized in neutral mucin cells and the basement membrane of the mantle, the oocytes and follicles of the gonad tissue, and in the digestive tissue of P. maculata. The ova and pharynx were the only two structures to contain TTX in Stylochoplana sp. Using liquid chromatography-mass spectrometry, TTX was identified in the larvae and eggs, but not the gelatinous egg cases of P. maculata. Tetrodotoxin was present in egg masses of Stylochoplana sp. These data suggest that TTX has a defensive function in adult P. maculata, who then invest this in their progeny for protection. Localization in the digestive tissue of P. maculata potentially indicates a dietary source of TTX. Stylochoplana sp. may use TTX in prey capture and for the protection of offspring

    Sequence-Specific Inhibition of a Nonspecific Protease

    Get PDF
    A nonspecific exopeptidase, aminopeptidase N (APN), is inhibited sequence-specifically by a synthetic host, cucurbit[7]uril (Q7), which binds with high affinity and specificity to N-terminal phenylalanine (Phe) and 4-(aminomethyl)phenylalanine (AMPhe) and prevents their removal from the peptide. Liquid chromatography experiments demonstrated that in the presence of excess Q7, APN quantitatively converts the pentapeptides Thr-Gly-Ala-X-Met into the dipeptides X-Met (X = Phe, AMPhe). The resulting Q7-bound products are completely stable to proteolytic digestion for at least 24 h. Structure–activity studies revealed a direct correlation between the extent of protection of an N-terminal amino acid and its affinity for Q7. Therefore, Q7 provides predictable sequence-specificity to an otherwise nonspecific protease and enables the production of a single peptide product. Conversely, APN uncovers a high-affinity epitope that is subsequently bound by Q7, and thus this approach should also facilitate the molecular recognition of peptides

    Leaf shape influences spatial variation in photosynthetic function in Lomatia tinctoria

    Full text link
    A relationship exists between the two-dimensional shape of leaves and their venation architecture, such that broad or broad-lobed leaves can have leaf tissue far from major veins, potentially creating stronger gradients in water potential - and associated photosynthetic function - than found across narrow counterparts. We examined the spatial patterns of photosynthetic efficiency (ΔF/Fm′) and non-photochemical quenching (NPQ) in response to increased vapour pressure deficit (VPD) using two morphs of Lomatia tinctoria (Labill.) R.Br: those with broad-lobed and those with narrow-lobed leaves. Stomatal conductance (gs), instantaneous water use efficiency (WUE), stomatal and minor veins density also were measured. ΔF/Fm′ decreased with stress but was higher and less spatially heterogeneous across broad than narrow lobes. The strongest depression in ΔF/Fm′ in broad lobes was at the edges and in narrow lobes, the tips. Non-photochemical quenching was spatially more varied in broad lobes, increasing at the edges and tips. Variation in photosynthetic function could not be explained by gs, WUE or minor vein density, whereas proximity to major veins appeared to mitigate water stress at the tips only for broad lobes. Our findings indicate that the relationship between venation architecture and water delivery alone can partially explain the spatial pattern of photosynthetic function. © CSIRO 2014

    Potassium homeostasis in vacuolate plant cells

    Get PDF
    Plant cells contain two major pools of K+, one in the vacuole and one in the cytosol. The behavior of K+ concentrations in these pools is fundamental to understanding the way this nutrient affects plant growth. Triple-barreled microelectrodes have been used to obtain the first fully quantitative measurements of the changes in K+ activity (aK) in the vacuole and cytosol of barley (Hordeum vulgare L.) root cells grown in different K+ concentrations. The electrodes incorporate a pH-selective barrel allowing each measurement to be assigned to either the cytosol or vacuole. The measurements revealed that vacuolar aK declined linearly with decreases in tissue K+ concentration, whereas cytosolic aK initially remained constant in both epidermal and cortical cells but then declined at different rates in each cell type. An unexpected finding was that cytoplasmic pH declined in parallel with cytosolic aK, but acidification of the cytosol with butyrate did not reveal any short-term link between these two parameters. These measurements show the very different responses of the vacuolar and cytosolic K+ pools to changes in K+ availability and also show that cytosolic K+ homeostasis differs quantitatively in different cell types. The data have been used in thermodynamic calculations to predict the need for, and likely mechanisms of, active K+ transport into the vacuole and cytosol. The direction of active K+ transport at the vacuolar membrane changes with tissue K+ status

    Importance of Non-Linear Couplings in Fusion Barrier Distributions and Mean Angular Momenta

    Full text link
    The effects of higher order coupling of surface vibrations to the relative motion on heavy-ion fusion reactions at near-barrier energies are investigated. The coupled channels equations are solved to all orders, and also in the linear and the quadratic coupling approximations. It is shown that the shape of fusion barrier distributions and the energy dependence of the average angular momentum of the compound nucleus can significantly change when the higher order couplings are included. The role of octupole vibrational excitation of ^{16}O in the ^{16}O + ^{144}Sm fusion reaction is also discussed using the all order coupled-channels equations.Comment: 8 pages, 6 figures, To be published in the Proceedings of the FUSION 97 Conference, South Durras, Australia, March 1997 (J. Phys. G

    Description of Nuclear Structure Effects in Subbarrier Fusion by the Interacting Boson Model

    Get PDF
    Recent theoretical developments in using the Interacting Boson Model to describe nuclear structure effects in fusion reactions below the Coulomb barrier are reviewed. Methods dealing with linear and all orders coupling between the nuclear excitations and the translational motion are discussed, and the latter is found to lead to a better description of the barrier distribution data. A systematic study of the available data (cross sections, barrier and spin distributions) in rare-earth nuclei is presented.Comment: 9 pages + 2 Figures (in eps form). To be published in the Proceedings of the FUSION97 Conference, South Durras, Australia, March 1997 (J. Phys. G). Full text and figures are also available at http://nucth.physics.wisc.edu/preprints/mad-nt-97-01.abs.htm
    corecore