661 research outputs found

    A Review of Maser Polarization and Magnetic Fields

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    Through polarization observations masers are unique probes of the magnetic field in a variety of different astronomical objects, with the different maser species tracing different physical conditions. In recent years maser polarization observations have provided insights in the magnetic field strength and morphology in, among others, the envelopes around evolved stars, Planetary Nebulae (PNe), massive star forming regions and supernova remnants. More recently, maser observations have even been used to determine the magnetic field in megamaser galaxies. This review will present an overview of maser polarization observations and magnetic field determinations of the last several years and discuss the implications of the magnetic field measurements for several important fields of study, such as aspherical PNe creation and massive star formation.Comment: 10 pages, Review paper from IAU symposium 242 "Astrophysical Masers and their Environments

    An inventory of Cicadellidae, Aphrophoridae, and Delphacidae (Hemiptera) in the Alvar Grasslands of the Maxton Plains, Michigan

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    Alvars are rare grassland communities found in the North American Great Lakes Region consisting of thin mineral soil over limestone bedrock and act as refugia for many unique and threatened endemic species. Few studies have catalogued Hemiptera species present in the alvars of the Maxton Plains on Drummond Island, MI. We aimed to add to these species lists, compare species diversity between alvar sites with varying levels of exposed bedrock, and test if an unpaved limestone road running through our sample sites influenced Hemipteran populations. We collected several prairie endemic species of Cicadellidae (Hemiptera), including a new record for the island, Laevicephalus unicoloratus. We found that pavement alvars, those with large portions of exposed bedrock, had higher species diversity on both of our collection dates despite having less overall vegetation when compared to grassland alvars with continuous soil coverage (H’ – Date 1: pavement = 0.649, grassland = 0.471; H’ – Date 2: pavement = 0.982, grassland = 0.855). We observed that distance relative to the unpaved limestone road affected the population densities of our target Hemiptera groups (Cicadellidae, Aphrophoridae, and Delphacidae), likely due to dust arising from dry conditions and road use. Our results, and the results of others, indicate the biological uniqueness of the alvars. Alvars face threats from off-road vehicle use, individual disregard for their conservation, and a changing climate. The continued monitoring, maintenance and protection of remaining alvars is imperative if their existence is to be continued beyond our lifetime

    An inventory of Cicadellidae, Aphrophoridae, and Delphacidae (Hemiptera) in the Alvar Grasslands of the Maxton Plains, Michigan

    Get PDF
    Alvars are rare grassland communities found in the North American Great Lakes Region consisting of thin mineral soil over limestone bedrock and act as refugia for many unique and threatened endemic species. Few studies have catalogued Hemiptera species present in the alvars of the Maxton Plains on Drummond Island, MI. We aimed to add to these species lists, compare species diversity between alvar sites with varying levels of exposed bedrock, and test if an unpaved limestone road running through our sample sites influenced Hemipteran populations. We collected several prairie endemic species of Cicadellidae (Hemiptera), including a new record for the island, Laevicephalus unicoloratus. We found that pavement alvars, those with large portions of exposed bedrock, had higher species diversity on both of our collection dates despite having less overall vegetation when compared to grassland alvars with continuous soil coverage (H’ – Date 1: pavement = 0.649, grassland = 0.471; H’ – Date 2: pavement = 0.982, grassland = 0.855). We observed that distance relative to the unpaved limestone road affected the population densities of our target Hemiptera groups (Cicadellidae, Aphrophoridae, and Delphacidae), likely due to dust arising from dry conditions and road use. Our results, and the results of others, indicate the biological uniqueness of the alvars. Alvars face threats from off-road vehicle use, individual disregard for their conservation, and a changing climate. The continued monitoring, maintenance and protection of remaining alvars is imperative if their existence is to be continued beyond our lifetime

    Reduction of Borazines Mediated by Low‐Valent Chromium Species

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95578/1/13168_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/95578/2/anie_201206668_sm_miscellaneous_information.pd
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