715 research outputs found

    Plant Secondary Compounds; Their Impact on Forage Nutritive Value and upon Animal Production

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    Both the anti-nutritional and beneficial effects of secondary compounds in a range of temperate and tropical forages have been reviewed. Major secondary compounds in temperate and tropical forage plants occur in the phenolic fraction and include condensed and hydrolysable tannins, phenolic monomers and lignin. Condensed tannins (CT) bind to plant protein by pH-reversible hydrogen bonding. In temperate legume forages this reduces rumen protein degradation and can increase the absorption of essential amino acids (EAA) from the small intestine, with reactivity depending on CT concentration, molecular weight and chemical structure. Low concentrations of CT in Lotus corniculatus (20-40g/kg DM) increased EAA absorption by 62% and increased wool growth (15%) and ovulation rate (25%) in grazing sheep and increased milk production in ewes and dairy cows, all without changing voluntary feed intake (VFI). High concentrations of CT in Lotus pedunculatus (80- 100 g/kg DM) depressed VFI and depressed rates of body and wool growth in grazing sheep. Sulla, containing 80-120 g CT/kg DM, was particularly effective for counteracting the effects of parasitism and for promoting high rates of body growth in parasitised lambs. CT is present in tropical species such as Leucaena and Acacia at higher concentrations (60-200 g/kg DM) than in temperate species. Action of CT reduced rumen protein degradation in sheep fed tropical forages, but as yet there is no convincing evidence that this leads to increases in EAA absorption from the small intestine or that CT increases animal production. Further research is needed in these areas with tropical forages, particularly on the relationship between CT structure and its reactivity with proteins. Increasing CT concentration did not depress rumen microbial protein synthesis in sheep fed either temperate or tropical forages, until CT concentration exceeded 130 g/kg DM. Effect of CT upon undegraded, dietary protein release in the small intestine and upon endogenous protein secretion is defined as a future research area. Flavonoids have been detected in tropical legume forages in the same concentrations as CT. They have anti-nutritional effects in terms of causing amino acid loss during their excretion as conjugates in the urine and by disturbing blood acid/base balance, leading to reduced VFI. Research currently in progress with other secondary compounds in both temperate and tropical forages is reviewed. This includes sesquiterpene lactones in chicory, acubin in plantain, isoflavones in red clover and coumarin and dihydro-coumarin in glyricidia. The nutritional and anti-nutritional effects of these compounds for both ruminants and non-ruminants is discussed

    A First Comparison of SLOPE and Other LIGO Burst Event Trigger Generators

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    A number of different methods have been proposed to identify unanticipated burst sources of gravitational waves in data arising from LIGO and other gravitational wave detectors. When confronted with such a wide variety of methods one is moved to ask if they are all necessary, i.e. given detector data that is assumed to have no gravitational wave signals present, do they generally identify the same events with the same efficiency, or do they each 'see' different things in the detector? Here we consider three different methods, which have been used within the LIGO Scientific Collaboration as part of its search for unanticipated gravitational wave bursts. We find that each of these three different methods developed for identifying candidate gravitational wave burst sources are, in fact, attuned to significantly different features in detector data, suggesting that they may provide largely independent lists of candidate gravitational wave burst events.Comment: 10 Pages, 5 Figures, Presented at the 10th Gravitational Wave Data Analysis Workshop (GWDAW-10), 14-17 December 2005 at the University of Texas, Brownsvill

    Optical extinction due to intrinsic structural variations of photonic crystals

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    Unavoidable variations in size and position of the building blocks of photonic crystals cause light scattering and extinction of coherent beams. We present a new model for both 2 and 3-dimensional photonic crystals that relates the extinction length to the magnitude of the variations. The predicted lengths agree well with our new experiments on high-quality opals and inverse opals, and with literature data analyzed by us. As a result, control over photons is limited to distances up to 50 lattice parameters (∌15ÎŒ\sim 15 \mum) in state-of-the-art structures, thereby impeding large-scale applications such as integrated circuits. Conversely, scattering in photonic crystals may lead to novel physics such as Anderson localization and non-classical diffusion.Comment: 10 pages, 3 figures. Changes include: added Lagendijk as author; simplified and generalized the tex

    Effect of Condensed Tannin in Lotus Corniculatus and Lotus Pedunculatus on Digestion of Rubisco in the Rumen

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    The in vitro precipitation of ribulose-1,5-bisphosphate carboxylase (Rubisco) by condensed tannin (CT) extracted from Lotus corniculatus and Lotus pedunculatus and the effect of these CT on the in vitro rumen degradation of Rubisco was used to compare the reactivity of these CT. The chemical structure of CT from Lotus corniculatus was homogenous with epicatechin stereochemistry and mostly procyanidin units. The CT from Lotus pedunculatus was heterogenous with mostly prodelphinidin units. The amount of CT required to precipitate all the Rubisco when total soluble leaf protein was incubated with CT from Lotus corniculatus and Lotus pedunculatus was similar. Although CT from both species were able to reduce the in vitro degradation of Rubisco, CT from Lotus corniculatus was less effective than CT from Lotus pedunculatus at reducing this degradation

    Overview of the BlockNormal Event Trigger Generator

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    In the search for unmodeled gravitational wave bursts, there are a variety of methods that have been proposed to generate candidate events from time series data. Block Normal is a method of identifying candidate events by searching for places in the data stream where the characteristic statistics of the data change. These change-points divide the data into blocks in which the characteristics of the block are stationary. Blocks in which these characteristics are inconsistent with the long term characteristic statistics are marked as Event-Triggers which can then be investigated by a more computationally demanding multi-detector analysis.Comment: GWDAW-8 proceedings, 6 pages, 2 figure

    Effect of Three Legumes Containing Different Condensed Tannin Concentrations on the in Vitro Formation of the Pastoral Flavour Compound; Skatole

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    Feeding legumes, such as white clover (Trifolium repens), results in higher intakes and increased animal production compared to grasses (Ulyatt, 1981). Skatole is produced in the rumen from plant protein fermentation and is associated with undesirable pastoral flavours in meat (Young et al. 2002). Feeding white clover causes a greater skatole concentration in the rumen compared to perennial ryegrass (Lolium perenne) or Lotus corniculatus, as the protein in white clover is highly soluble and rapidly degraded (Schreurs et al., 2004). The condensed tannins (CT) in Lotus species slow protein degradation in the rumen (Aerts et al., 1999). The aim of this study was to determine the effect of legumes with different concentrations of CT on skatole formation

    Grasses as Biofactories: Scoping out the Opportunities

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    Key points 1. Plant biopharming is set to dominate commercial recombinant protein expression for specific proteins. 2. The choice of plant species depends on a multitude of factors and is determined on a caseby- case basis. 3. As a leaf based expression system grasses would have to compete predominantly with tobacco and alfalfa. 4. The grass-endophyte symbiosis offers a number of unique possibilities for biopharming

    The acheulean handaxe : More like a bird's song than a beatles' tune?

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    © 2016 Wiley Periodicals, Inc. KV is supported by the Netherlands Organization for Scientific Research. MC is supported by the Canada Research Chairs Program, the Social Sciences and Humanities Research of Canada, the Canada Foundation for Innovation, the British Columbia Knowledge Development Fund, and Simon Fraser UniversityPeer reviewedPublisher PD

    Spectroscopy of 194^{194}Po

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    Prompt, in-beam γ\gamma rays following the reaction 170^{170}Yb + 142 MeV 28^{28}Si were measured at the ATLAS facility using 10 Compton-suppressed Ge detectors and the Fragment Mass Analyzer. Transitions in 194^{194}Po were identified and placed using γ\gamma-ray singles and coincidence data gated on the mass of the evaporation residues. A level spectrum up to J≈\approx10ℏ\hbar was established. The structure of 194^{194}Po is more collective than that observed in the heavier polonium isotopes and indicates that the structure has started to evolve towards the more collective nature expected for deformed nuclei.Comment: 8 pages, revtex 3.0, 4 figs. available upon reques
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