The pollinators of Echinacea angustifolia in Saskatchewan

Non-Peer ReviewedEchinacea (Asteraceae) is grown as a nutraceutical crop and is one of the best selling medicinal plants on the North American market today, accounting for over 300 million dollars annually in sales. Echinacea angustifolia accounts for the majority of Echinacea produced in Saskatchewan and is native to the southern regions of the Canadian Prairies. Echinacea must be cross-pollinated to set seed, as is typical of members of the Asteraceae, and only insects can effect cross-pollination. An in-depth knowledge of Echinacea’s pollination system is essential to developing Echinacea as a sustainable market crop. E. angustifolia’s native pollinators are being identified and their pollination efficiencies assessed by pollen-tube quantification after visiting previously unvisited inflorescences. Interestingly, the recent abundance of grasshoppers in Saskatchewan has supported large populations of potential pollinators of E. angustifolia. For instance, the grasshopper bee fly (Systoechus vulgaris) and the golden blister beetle (Epicauta ferruginea) were particularly abundant on E. angustifolia inflorescences in the summer of 2003 and their contributions to pollination are being assessed. Alfalfa leafcutting bees (Megachile rotundata) managed in Saskatchewan as pollinators of alfalfa (Medicago sativum) have the potential to be excellent managed pollinators of Echinacea; this project will evaluate their pollination efficiency

The influence of nectar sugar production on insect visitors to flowers of Brassica rapa L.

Non-Peer ReviewedThe purpose of this study was to determine if differing amounts of floral nectar sugar could affect the insect pollination of Brassica rapa L., a self-incompatible species. This knowledge could be directly applicable to crop-breeding programs interested in maintaining or enhancing the attractiveness of flowers to nectar-foraging visitors (possible pollinators). Several lines of rapid-cycling B. rapa were assayed (microcapillary nectar collection plus refractometry) for floral nectar-sugar production, and seed increases were made from plants selected on that basis. Both high and low nectar-producing plants were crossed reciprocally (high by high and low by low) in attempts to establish progenies distinct from each other. It appeared that reliably high and low nectar-yielding lines could be established. Outdoor insect visitation trials using high, intermediate, and low nectar-yielding lines of rapid-cycling plants of B. rapa in small plots resulted in more insects (especially flies and bees) visiting the high nectar-producing line, which in turn produced more seeds per silique

Spectral Orbits and Peak-to-Average Power Ratio of Boolean Functions with respect to the {I,H,N}^n Transform

We enumerate the inequivalent self-dual additive codes over GF(4) of blocklength n, thereby extending the sequence A090899 in The On-Line Encyclopedia of Integer Sequences from n = 9 to n = 12. These codes have a well-known interpretation as quantum codes. They can also be represented by graphs, where a simple graph operation generates the orbits of equivalent codes. We highlight the regularity and structure of some graphs that correspond to codes with high distance. The codes can also be interpreted as quadratic Boolean functions, where inequivalence takes on a spectral meaning. In this context we define PAR_IHN, peak-to-average power ratio with respect to the {I,H,N}^n transform set. We prove that PAR_IHN of a Boolean function is equivalent to the the size of the maximum independent set over the associated orbit of graphs. Finally we propose a construction technique to generate Boolean functions with low PAR_IHN and algebraic degree higher than 2.Comment: Presented at Sequences and Their Applications, SETA'04, Seoul, South Korea, October 2004. 17 pages, 10 figure

Which effective viscosity?

Magmas undergoing shear are prime examples of flows that involve the transport of solids and gases by a separate (silicate melt) carrier phase. Such flows are called multiphase, and have attracted much attention due to their important range of engineering applications. Where the volume fraction of the dispersed phase (crystals) is large, the influence of particles on the fluid motion becomes significant and must be taken into account in any explanation of the bulk behaviour of the mixture. For congested magma deforming well in excess of the dilute limit (particle concentrations >40% by volume), sudden changes in the effective or relative viscosity can be expected. The picture is complicated further by the fact that the melt phase is temperature- and shear-rate-dependent. In the absence of a constitutive law for the flow of congested magma under an applied force, it is far from clear which of the many hundreds of empirical formulae devised to predict the rheology of suspensions as the particle fraction increases with time are best suited. Some of the more commonly used expressions in geology and engineering are reviewed with an aim to home in on those variables key to an improved understanding of magma rheology. These include a temperature, compositional and shear-rate dependency of viscosity of the melt phase with the shear-rate dependency of the crystal (particle) packing arrangement. Building on previous formulations, a new expression for the effective (relative) viscosity of magma is proposed that gives users the option to define a packing fraction range as a function of shear stress. Comparison is drawn between processes (segregation, clustering, jamming), common in industrial slurries, and structures seen preserved in igneous rocks. An equivalence is made such that congested magma, viewed in purely mechanical terms as a high-temperature slurry, is an inherently non-equilibrium material where flow at large Péclet numbers may result in shear thinning and spontaneous development of layering

Inflation driven by scalar field with non-minimal kinetic coupling with Higgs and quadratic potentials

We study a scalar field with non-minimal kinetic coupling to itself and to the curvature. The slow rolling conditions allowing an inflationary background have been found. The quadratic and Higgs type potentials have been considered, and the corresponding values for the scalar fields at the end of inflation allows to recover the connection with particle physics.Comment: 16 pages, to appear in JCA

Inhibition of osteocyte apoptosis prevents the increase in osteocytic receptor activator of nuclear factor κB ligand (RANKL) but does not stop bone resorption or the loss of bone induced by unloading

"This research was originally published in Journal of Biological Chemistry. Lilian I. Plotkin, Arancha R. Gortazar, Hannah M. Davis, Keith W. Condon, Hugo Gabilondo, Marta Maycas, Matthew R. Allen, and Teresita Bellido. Inhibition of Osteocyte Apoptosis Prevents the Increase in Osteocytic Receptor Activator of Nuclear Factor κB Ligand (RANKL) but Does Not Stop Bone Resorption or the Loss of Bone Induced by Unloading*. Journal of Biological Chemistry. 2015; 290:18934-18942. © the American Society for Biochemistry and Molecular Biology."Apoptosis of osteocytes and osteoblasts precedes bone resorption and bone loss with reduced mechanical stimulation, and receptor activator of NF-κB ligand (RANKL) expression is increased with unloading in mice. Because osteocytes are major RANKL producers, we hypothesized that apoptotic osteocytes signal to neighboring osteocytes to increase RANKL expression, which, in turn, increases osteoclastogenesis and bone resorption. The traditional bisphosphonate (BP) alendronate (Aln) or IG9402, a BP analog that does not inhibit resorption, prevented the increase in osteocyte apoptosis and osteocytic RANKL expression. The BPs also inhibited osteoblast apoptosis but did not prevent the increase in osteoblastic RANKL. Unloaded mice exhibited high serum levels of the bone resorption marker C-telopeptide fragments of type I collagen (CTX), elevated osteoclastogenesis, and increased osteoclasts in bone. Aln, but not IG9402, prevented all of these effects. In addition, Aln prevented the reduction in spinal and femoral bone mineral density, spinal bone volume/tissue volume, trabecular thickness, mechanical strength, and material strength induced by unloading. Although IG9402 did not prevent the loss of bone mass, it partially prevented the loss of strength, suggesting a contribution of osteocyte viability to strength independent of bone mass. These results demonstrate that osteocyte apoptosis leads to increased osteocytic RANKL. However, blockade of these events is not sufficient to restrain osteoclast formation, inhibit resorption, or stop bone loss induced by skeletal unloadingThis work was supported, in whole or in part, by National Institutes of Health Grants R01DK076007 and ARRA supplement S10-RR023710 (to T. B.) and R01AR053643 (to L. I. P.). This work was also supported by Veterans Affairs Merit Award I01BX002104 (to T. B.) and an IUSM Biomedical Research grant (to L. I. P.) and by scholarships from the Conchita Rábago Foundation (to A. R. G. and M. M.), the European Molecular Biology Organization (to M. M.), and Universidad Autónoma de Madrid (to H. G

Parity Violation in Proton-Proton Scattering at 221 MeV

TRIUMF experiment 497 has measured the parity violating longitudinal analyzing power, A_z, in pp elastic scattering at 221.3 MeV incident proton energy. This paper includes details of the corrections, some of magnitude comparable to A_z itself, required to arrive at the final result. The largest correction was for the effects of first moments of transverse polarization. The addition of the result, A_z=(0.84 \pm 0.29 (stat.) \pm 0.17 (syst.)) \times 10^{-7}, to the pp parity violation experimental data base greatly improves the experimental constraints on the weak meson-nucleon coupling constants h^{pp}_\rho and h^{pp}_\omega, and has implications for the interpretation of electron parity violation experiments.Comment: 17 pages RevTeX, 14 PostScript figures. Revised version with additions suggested by Phys. Rev.

Limits on the gravity wave contribution to microwave anisotropies

We present limits on the fraction of large angle microwave anisotropies which could come from tensor perturbations. We use the COBE results as well as smaller scale CMB observations, measurements of galaxy correlations, abundances of galaxy clusters, and Lyman alpha absorption cloud statistics. Our aim is to provide conservative limits on the tensor-to-scalar ratio for standard inflationary models. For power-law inflation, for example, we find T/S<0.52 at 95% confidence, with a similar constraint for phi^p potentials. However, for models with tensor amplitude unrelated to the scalar spectral index it is still currently possible to have T/S>1.Comment: 23 pages, 7 figures, accepted for publication in Phys. Rev. D. Calculations extended to blue spectral index, Fig. 6 added, discussion of results expande

O adsorption and incipient oxidation of the Mg(0001) surface

First principles density functional calculations are used to study the early oxidation stages of the Mg(0001) surface for oxygen coverages 1/16 <= Theta <= 3 monolayers. It is found that at very low coverages O is incorporated below the topmost Mg layer in tetrahedral sites. At higher oxygen-load the binding in on-surface sites is increased but at one monolayer coverage the on-surface binding is still about 60 meV weaker than for subsurface sites. The subsurface octahedral sites are found to be unfavorable compared to subsurface tetrahedral sites and to on-surface sites. At higher coverages oxygen adsorbs both under the surface and up. Our calculations predict island formation and clustering of incorporated and adsorbed oxygen in agreement with previous calculations. The calculated configurations are compared with the angle-scanned x-ray photoelectron diffraction experiment to determine the geometrical structure of the oxidized Mg(0001) surface.Comment: 10 pages, 5 figure