699 research outputs found

    How to improve Drenchrite

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    Understanding the strengths and weaknesses of DrenchRite and how it relates to faecal egg count reduction tests (FECRT) will lead to clearer interpretation of DrenchRite results and a better perspective on both tests. In previous studies efficacy was estimated for worms resistant to BZ, LEV and BZILEV combinations by FECRT, DrenchRite and post mortem worm counts. Correlations of in vivo efficacy with FECRT determined by them were: Trichostrongylus colubriformis 88%, Ostertagia circumcincta 56% and Haemonchus contortus 69%. The low correlation for O. circumcincta was associated with the variability in estimating species composition when O. circumcincta was present at low levels. Correlations of DrenchRite with in vivo efficacy were: O. circumcincta 87%, T. colubriformis 82% and H. contortus 80%. The correlation between resistance determined by Larval Development Assay (LDA) and FECRT was not high at 61% (averaged over drugs and species). Similar data for Macrocyclic Lactones (ML) resistant worms are not yet available. Previous studies have shown for some LDA systems that eggs are more likely to be inhibited in development to L3s early (2-3 weeks post infection (PI)) and late (beyond 10 weeks PI) after infection and are most resilient to the effect of drugs at about 7 weeks PI. No systematic changes in DrenchRite results were observed over age of worm infection when tested weekly for 2 to 14 week old worms. Large bowel worms of sheep have not generally been examined under LDA conditions so a study was undertaken to determine the LD50s of susceptible Oesophagostomum columbianum (nodule worm) and Chabertia ovina (large mouthed bowel worm) on DrenchRite plates. LD50s for BZ and LEV were approximately 0.04 and 0.8 uM respectively for both worms. For the ML O. columbianum had a much higher LD50 (45 nM) than C. ovina (8 nM). In relation to the other common sheep worms, development characteristics of C. ovina in LDA is like H. contortus while O. columbianum is more like O. circumcincta. Both large bowel worms were very sensitive to BZILEV combinations, with LD50s 4 to 8 fold lower than those observed for H. contortus and O. circumcincta

    Bone mineral density and risk of heart failure in older adults: The Cardiovascular Health Study

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    Background Despite increasing evidence of a common link between bone and heart health, the relationship between bone mineral density ( BMD ) and heart failure ( HF ) risk remains insufficiently studied. Methods and Results We investigated whether BMD measured by dual‐energy x‐ray absorptiometry was associated with incident HF in an older cohort. Cox models were stratified by sex and interactions of BMD with race assessed. BMD was examined at the total hip and femoral neck separately, both continuously and by World Health Organization categories. Of 1250 participants, 442 (55% women) developed HF during the median follow‐up of 10.5 years. In both black and nonblack women, neither total hip nor femoral neck BMD was significantly associated with HF ; there was no significant interaction by race. In black and nonblack men, total hip, but not femoral neck, BMD was significantly associated with HF , with evidence of an interaction by race. In nonblack men, lower total hip BMD was associated with higher HF risk (hazard ratio, 1.13 [95% CI, 1.01–1.26] per 0.1 g/cm 2 decrement), whereas in black men, lower total hip BMD was associated with lower HF risk (hazard ratio, 0.74 [95% CI, 0.59–0.94]). There were no black men with total hip osteoporosis. Among nonblack men, total hip osteoporosis was associated with higher HF risk (hazard ratio, 2.83 [95% CI, 1.39–5.74]) compared with normal BMD . Conclusions Among older adults, lower total hip BMD was associated with higher HF risk in nonblack men but lower risk in black men, with no evidence of an association in women. Further research is needed to replicate these findings and to study potential underlying pathways. </jats:sec

    Diffractive Meson Production and the Quark-Pomeron Coupling

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    Diffractive meson production at HERA offers interesting possibilities to investigate diffractive processes and thus to learn something about the properties of the pomeron. The most succesful phenomenological description of the pomeron so far assumes it to couple like a C=+1C = +1 isoscalar photon to single quarks. This coupling leads, however, to problems for exclusive diffractive reactions. We propose a new phenomenological pomeron vertex, which leads to very good fits to the known data, but avoids the problems of the old vertex.Comment: 20 pages, latex with uuencoded postscript, revised versio

    Elliptic curves of large rank and small conductor

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    For r=6,7,...,11 we find an elliptic curve E/Q of rank at least r and the smallest conductor known, improving on the previous records by factors ranging from 1.0136 (for r=6) to over 100 (for r=10 and r=11). We describe our search methods, and tabulate, for each r=5,6,...,11, the five curves of lowest conductor, and (except for r=11) also the five of lowest absolute discriminant, that we found.Comment: 16 pages, including tables and one .eps figure; to appear in the Proceedings of ANTS-6 (June 2004, Burlington, VT). Revised somewhat after comments by J.Silverman on the previous draft, and again to get the correct page break

    Multiscale magnetic underdense regions on the solar surface: Granular and Mesogranular scales

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    The Sun is a non-equilibrium dissipative system subjected to an energy flow which originates in its core. Convective overshooting motions create temperature and velocity structures which show a temporal and spatial evolution. As a result, photospheric structures are generally considered to be the direct manifestation of convective plasma motions. The plasma flows on the photosphere govern the motion of single magnetic elements. These elements are arranged in typical patterns which are observed as a variety of multiscale magnetic patterns. High resolution magnetograms of quiet solar surface revealed the presence of magnetic underdense regions in the solar photosphere, commonly called voids, which may be considered a signature of the underlying convective structure. The analysis of such patterns paves the way for the investigation of all turbulent convective scales from granular to global. In order to address the question of magnetic structures driven by turbulent convection at granular and mesogranular scales we used a "voids" detection method. The computed voids distribution shows an exponential behavior at scales between 2 and 10 Mm and the absence of features at 5-10 Mm mesogranular scales. The absence of preferred scales of organization in the 2-10 Mm range supports the multiscale nature of flows on the solar surface and the absence of a mesogranular convective scale

    A dimensionally continued Poisson summation formula

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    We generalize the standard Poisson summation formula for lattices so that it operates on the level of theta series, allowing us to introduce noninteger dimension parameters (using the dimensionally continued Fourier transform). When combined with one of the proofs of the Jacobi imaginary transformation of theta functions that does not use the Poisson summation formula, our proof of this generalized Poisson summation formula also provides a new proof of the standard Poisson summation formula for dimensions greater than 2 (with appropriate hypotheses on the function being summed). In general, our methods work to establish the (Voronoi) summation formulae associated with functions satisfying (modular) transformations of the Jacobi imaginary type by means of a density argument (as opposed to the usual Mellin transform approach). In particular, we construct a family of generalized theta series from Jacobi theta functions from which these summation formulae can be obtained. This family contains several families of modular forms, but is significantly more general than any of them. Our result also relaxes several of the hypotheses in the standard statements of these summation formulae. The density result we prove for Gaussians in the Schwartz space may be of independent interest.Comment: 12 pages, version accepted by JFAA, with various additions and improvement

    Friedmann Equation and Stability of Inflationary Higher Derivative Gravity

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    Stability analysis on the De Sitter universe in pure gravity theory is known to be useful in many aspects. We first show how to complete the proof of an earlier argument based on a redundant field equation. It is shown further that the stability condition applies to k0k \ne 0 Friedmann-Robertson-Walker spaces based on the non-redundant Friedmann equation derived from a simple effective Lagrangian. We show how to derive this expression for the Friedmann equation of pure gravity theory. This expression is also generalized to include scalar field interactions.Comment: Revtex, 6 pages, Add two more references, some typos correcte

    Solar Intranetwork Magnetic Elements: bipolar flux appearance

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    The current study aims to quantify characteristic features of bipolar flux appearance of solar intranetwork (IN) magnetic elements. To attack such a problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and an enhanced network areas. Cluster emergence of mixed polarities and IN ephemeral regions (ERs) are the most conspicuous forms of bipolar flux appearance within the network. Each of the clusters is characterized by a few well-developed ERs that are partially or fully co-aligned in magnetic axis orientation. On average, the sampled IN ERs have total maximum unsigned flux of several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes. The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx, separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN ERs exhibit a rotation of their magnetic axis of more than 10 degrees during flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by growth or the reverse, is not unusual. A few examples show repeated shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic photosphere. The observed bipolar behavior seems to carry rich information on magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure

    Fusion of secretory vesicles isolated from rat liver

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    Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells. Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system. The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences
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