2,692 research outputs found

    An Improved Estimate of the Mass of Dust in Cassiopeia A

    Full text link
    Recent observations of sub-millimeter continuum emission toward supernova remnants (SNR) have raised the question of whether such emission is caused by dust within the SNR and thus produced by the supernova itself or along the line-of-sight. The importance of the present work is to establish evidence for the production of large amounts of dust in supernovae. The best tests can be made for young supernovae in our galaxy. Cassiopeia A is the best candidate for a measurement.Comment: 7 pages, 3 figures, accepted by A&A for publicatio

    Disrupted gene networks in subfertile hybrid house mice

    Get PDF
    The Dobzhansky–Muller (DM) model provides a widely accepted mechanism for the evolution of reproductive isolation: incompatible substitutions disrupt interactions between genes. To date, few candidate incompatibility genes have been identified, leaving the genes driving speciation mostly uncharacterized. The importance of interactions in the DM model suggests that gene coexpression networks provide a powerful framework to understand disrupted pathways associated with postzygotic isolation. Here, we perform weighted gene coexpression network analysis to infer gene interactions in hybrids of two recently diverged European house mouse subspecies, Mus mus domesticus and M. m. musculus, which commonly show hybrid male sterility or subfertility. We use genome-wide testis expression data from 467 hybrid mice from two mapping populations: F2s from a laboratory cross between wild-derived pure subspecies strains and offspring of natural hybrids captured in the Central Europe hybrid zone. This large data set enabled us to build a robust consensus network using hybrid males with fertile phenotypes. We identify several expression modules, or groups of coexpressed genes, that are disrupted in subfertile hybrids, including modules functionally enriched for spermatogenesis, cilium and sperm flagellum organization, chromosome organization, and DNA repair, and including genes expressed in spermatogonia, spermatocytes, and spermatids. Our network-based approach enabled us to hone in on specific hub genes likely to be influencing module-wide gene expression and hence potentially driving large-effect DM incompatibilities. A disproportionate number of hub genes lie within sterility loci identified previously in the hybrid zone mapping population and represent promising candidate barrier genes and targets for future functional analysis

    Si microwire-array solar cells

    Get PDF
    Si microwire-array solar cells with Air Mass 1.5 Global conversion efficiencies of up to 7.9% have been fabricated using an active volume of Si equivalent to a 4 μm thick Si wafer. These solar cells exhibited open-circuit voltages of 500 mV, short-circuit current densities (J_(sc)) of up to 24 mA cm^(-2), and fill factors >65% and employed Al_2O_3 dielectric particles that scattered light incident in the space between the wires, a Ag back reflector that prevented the escape of incident illumination from the back surface of the solar cell, and an a-SiN_x:H passivation/anti-reflection layer. Wire-array solar cells without some or all of these design features were also fabricated to demonstrate the importance of the light-trapping elements in achieving a high J_(sc). Scanning photocurrent microscopy images of the microwire-array solar cells revealed that the higher J_(sc) of the most advanced cell design resulted from an increased absorption of light incident in the space between the wires. Spectral response measurements further revealed that solar cells with light-trapping elements exhibited improved red and infrared response, as compared to solar cells without light-trapping elements

    Photoelectrochemical Hydrogen Evolution Using Si Microwire Arrays

    Get PDF
    Arrays of B-doped p-Si microwires, diffusion-doped with P to form a radial n+ emitter and subsequently coated with a 1.5-nm-thick discontinuous film of evaporated Pt, were used as photocathodes for H_2 evolution from water. These electrodes yielded thermodynamically based energy-conversion efficiencies >5% under 1 sun solar simulation, despite absorbing less than 50% of the above-band-gap incident photons. Analogous p-Si wire-array electrodes yielded efficiencies <0.2%, largely limited by the low photovoltage generated at the p-Si/H_2O junction

    CeCoIn5 - a quantum critical superfluid

    Full text link
    We have made the first complete measurements of the London penetration depth λ(T)\lambda(T) of CeCoIn5, a quantum-critical metal where superconductivity arises from a non-Fermi-liquid normal state. Using a novel tunnel diode oscillator designed to avoid spurious contributions to λ(T)\lambda(T), we have established the existence of intrinsic and anomalous power-law behaviour at low temperature. A systematic analysis raises the possibility that the unusual observations are due to an extension of quantum criticality into the superconducting state.Comment: 5 pages, 3 figure

    The Iowa Homemaker vol.7, no.1

    Get PDF
    Table of Contents Modern Dress – Controversial Article, page 1 What’s In a Name? by Marcia E. Turner, page 2 Helps for the Spring Market Basket by Margaret L. Marnette, page 3 Lacquer for Ktichen Tables by Della J. Norton, page 3 A Pressure or a Fireless Cooker – Which? by Ethel Cessna Morgan, page 4 4-H Page, page 6 Iowa State Home Economics Association Page, page 8 News Notes, page 10 Editorial, page 11 Who’s There and Where, page 12 The Children’s Hour by Mary E. Moser, page 14 Hammer, Saw, Paint Brush and Nerve by Eleanor Baur, page 15 Had Your Iron Today?, page 1

    The Iowa Homemaker vol.8, no.6

    Get PDF
    Pictures for the Home and School by Joanne M. Hansen, page 1 Waste in Leisure by Ethyl Cessna Morgan, page 2 Sauce for the Goose by Margaret L. Marnette, page 3 Estonia Sends Another Student by Isabel Leith, page 4 Home Economics Research by Mildred Deischer, page 5 Girls’ 4-H Clubs by Lulu Tregoning, page 6 State Association Page by Marcia E. Turner, page 8 Editorial, page 11 Who’s There and Where by Vera Caulum, page 1

    Troubling meanings of family and competing moral imperatives in the family lives of young people with a parent who is at the end of life

    Get PDF
    This article draws on a narrative study of young people with a parent who is at the end of life to examine how family lives are troubled by life-limiting parental illness. Young people struggled to reconcile the physical and emotional absence of family members with meanings of ‘family’; the extent to which young people could rely on family to ‘be there’ in these troubling circumstances was of practical, emotional and moral significance. Our discussion is situated in the context of an English end of life care policy predicated on the ideal of a good death as one that takes place at home accompanied by family members. We explore how the shift away from family as a site for nurturing children towards family as a space to care for the dying is experienced by young people, and consider how these competing moral imperatives are negotiated through relational practices of care
    • …
    corecore