6,746 research outputs found

    Remembering T.W. Schultz, breaker of new ground

    Get PDF
    Teaching/Communication/Extension/Profession,

    Chalcosicya maya n. sp, a new Mexican species (Coleoptera: Chrysomelidae: Eumoplinae) and its implications for morphology and biogeography

    Get PDF
    Chalcosicya maya, new species, (Coleoptera: Chrysomelidae: Eumolpinae) is described and the species key of Blake (1951) is modified to accommodate it. This is the first known mainland species of this previously Antillean genus. Sclerotized rods in the apical segment of the ovipositor of Chalcosicya Blake and related genera are shown to be useful systematic characters within the eumolpine tribe Adoxini. Relationships with other genera suggest that Chalcosicya belongs to a clade derived from ancestors with a western Tethyian distribution.Se describe Chalcosicya maya especie nueva (Coleoptera: Chrysomelidae: Eumolpinae). Esta es la primera especie conocida de tierra continente de este género previamente Antillano. La clave a las especies de Blake (1951) está modificado para acomodar esta especie nueva. Bielas esclerotizadas en el segmento apical del ovipositor en Chalcosicya y en géneros relacionados se ven como characteres filogeneticos útiles dentro del tribo Adoxini. Relaciones con otros géneros sugieren que Chalcosicya pertence a un clado derivado de ancestros con una distribución del Tethys oeste

    Heptageniidae (Ephemeroptera) of Wisconsin

    Get PDF
    (excerpt) Heptageniidae are one of the most abundant and widespread components of Wisconsin\u27s aquatic insect fauna. In almost any stream with a firm substrate and free of gross pollution, the flattened nymphs can be found hiding in crevasses and under rocks, or clinging to submerged wood. Adults and nymphs are easily distinguished from mayflies of other families, nymphs by their dorsoventrally flattened head and dorsal eyes, and adults by their 5-segmented tarsi and complete wing veination. This paper presents our knowledge to date of Heptageniidae in Wisconsin

    Development and evaluation of die and container materials

    Get PDF
    X = 0.75 Beta prime Sialon (a silicon aluminum oxynitride) and Sibeon (silicon beryllium oxynitride) are promising die materials. In sessile drop tests in contact with molten silicon, beryllium contamination was less than ppm and aluminum contamination 50 ppm. A shaping die of the Sialon material was successfully fabricated. Dry milling studies for the preparation of Si3N4-Al2O3-ALN mixtures were performed with butanol, acetic anhydride, oleic acid, and triethanolamine milling aids. Optimum mixing was achieved with 0.15 percent triethanolamine using a milling time of 8 hours. Preliminary evaluation of Sibeon materials indicates that they are more resistent to molten silicon attack than Sialon. Silicon contamination from the beryllium was less than aluminum contamination even though the aluminum impurity level in the Sibeon was only 450 to 1300 ppm. Work designed to produce an aluminum-free Sibeon is described

    Inelastic neutron scattering studies of the quantum frustrated magnet clinoatacamite, γ\gamma-Cu2(OD)3Cl, a proposed valence bond solid (VBS)

    Full text link
    The frustrated magnet clinoatacamite, γ\gamma-Cu2_2(OH)3_3Cl, is attracting a lot of interest after suggestions that at low temperature it forms an exotic quantum state termed a Valence Bond Solid (VBS) made from dimerised Cu2+^{2+} (S=1/2S=1/2) spins.\cite{Lee_clinoatacamite} Key to the arguments surrounding this proposal were suggestions that the kagom\'e planes in the magnetic pyrochlore lattice of clinoatacamite are only weakly coupled, causing the system to behave as a quasi-2-dimensional magnet. This was reasoned from the near 95^\circ angles made at the bridging oxygens that mediate exchange between the Cu ions that link the kagom\'e planes. Recent work pointed out that this exchange model is inappropriate for γ\gamma-Cu2_2(OH)3_3Cl, where the oxygen is present as a μ3\mu_3-OH.\cite{Wills_JPC} Further, it used symmetry calculations and neutron powder diffraction to show that the low temperature magnetic structure (T<6T<6 K) was canted and involved significant spin ordering on all the Cu2+^{2+} spins, which is incompatible with the interpretation of simultaneous VBS and N\'eel ordering. Correspondingly, clinoatacamite is best considered a distorted pyrochlore magnet. In this report we show detailed inelastic neutron scattering spectra and revisit the responses of this frustrated quantum magnet.Comment: Proceedings of The International Conference on Highly Frustrated Magnetism 2008 (HFM2008

    A Parsec-Scale Study of the 5/15 GHz Spectral Indices of the Compact Radio Sources in M82

    Get PDF
    Observations of the starburst galaxy, M82, have been made with the VLA in its A-configuration at 15 GHz and MERLIN at 5 GHz enabling a spectral analysis of the compact radio structure on a scale of < 0.1'' (1.6 pc). Crucial to these observations was the inclusion of the Pie Town VLBA antenna, which increased the resolution of the VLA observations by a factor of ~2. A number of the weaker sources are shown to have thermal spectra and are identified as HII regions with emission measures ~10^7 cm^-6 pc. Some of the sources appear to be optically thick at 5 GHz implying even higher emission measures of ~10^8 cm^-6 pc. The number of compact radio sources in M82 whose origin has been determined is now 46, of which 30 are supernova related and the remaining 16 are HII regions. An additional 15 sources are noted, but have yet to be identified, meaning that the total number of compact sources in M82 is at least 61. Also, it is shown that the distribution of HII regions is correlated with the large-scale ionised gas distribution, but is different from the distribution of supernova remnants. In addition, the brightest HII region at (B1950) 09h 51m 42.21s +69 54' 59.2'' shows a spectral index gradient across its resolved structure which we attribute to the source becoming optically thick towards its centre.Comment: Accepted for publication in MNRAS. 15 pages, 9 figure

    Expert Finding by Capturing Organisational Knowledge from Legacy Documents

    No full text
    Organisations capitalise on their best knowledge through the improvement of shared expertise which leads to a higher level of productivity and competency. The recognition of the need to foster the sharing of expertise has led to the development of expert finder systems that hold pointers to experts who posses specific knowledge in organisations. This paper discusses an approach to locating an expert through the application of information retrieval and analysis processes to an organization’s existing information resources, with specific reference to the engineering design domain. The approach taken was realised through an expert finder system framework. It enables the relationships of heterogeneous information sources with experts to be factored in modelling individuals’ expertise. These valuable relationships are typically ignored by existing expert finder systems, which only focus on how documents relate to their content. The developed framework also provides an architecture that can be easily adapted to different organisational environments. In addition, it also allows users to access the expertise recognition logic, giving them greater trust in the systems implemented using this framework. The framework were applied to real world application and evaluated within a major engineering company
    corecore