1,193 research outputs found

    JSTOR Plant Science

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    JSTOR Plant Science is an online environment that brings together content, tools, and people interested in plant science. It provides access to foundational content vital to plant science – plant type specimens, taxonomic structures, scientific literature, and related materials, making them widely accessible to the plant science community as well as to researchers in other fields and to the public. It also provides an easy to use interface with powerful functionality that supports research and teaching, including the ability to measure and record plant specimens, share observations and objects with colleagues and classmates, and investigate global plant biodiversity

    CFHT Legacy Ultraviolet Extension (CLUE): witnessing galaxy transformations up to 7 Mpc from rich cluster cores

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    Using the optical data from the Wide component of the Canada-France-Hawaii Telescope (CFHT) Legacy Survey, and new ultraviolet (UV) data from GALEX, we study the colours and specific star formation rates (SSFRs) of ∼ 100 galaxy clusters at 0.16 < z < 0.36, over areas extending out to radii of r∼ 7 Mpc. We use a multicolour, statistical background subtraction method to study the galaxy population at this radius; thus our results pertain to those galaxies which constitute an excess over the average field density. We find that the average SSFR and its distribution of the star-forming galaxies (with at z∼ 0.2 and at z∼ 0.3) have no measurable dependence on the clustercentric radius and are consistent with the field values. However, the fraction of galaxies with SFR above these thresholds, and the fraction of optically blue galaxies, are lower for the overdense galaxy population in the cluster outskirts compared with the average field value, at all stellar masses and at all radii out to at least 7 Mpc. Most interestingly, the fraction of blue galaxies that are forming stars at a rate below our UV detection limit is much higher in all radial bins around our cluster sample compared with the general field value. This is most noticeable for massive galaxies ; while almost all blue field galaxies of this mass have detectable star formation, this is true for less than 20 per cent of the blue cluster galaxies, even at 7 Mpc from the cluster centre. Our results support a scenario where galaxies are pre-processed in locally overdense regions in a way that reduces their SFR below our UV detection limit, but not to zer

    Geomagnetic conditions in Ireland During the St. Patrick's Day 2015 Storm

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    <p>Poster at UK National Astronomy Meeting in Llandudno, Wales on July 5-9, 2015 (www.nam2015.org)</p> <p>Abstract:</p> <p>Two coronal mass ejections were launched in quick succession from the Sun on March 15, 2015. They impacted the Earth's magnetosphere two days later on St. Patrick's Day (March 17), resulting in a geomagnetic storm with a planetary K-Index of 8.</p> <p>Magnetic variations were measured across a recently deployed magnetometer network in Ireland and geoelectric fields were measured at a site in Co. Leitrim (magnetic latitude 57.08°). A local K-index maximum of 7 was calculated at Birr, Co. Offaly (magnetic latitude 55.97), while the aurora</p> <p>borealis accompanying the geomagnetic storm was visible as far south as Co. Waterford (magnetic latitude 55.13°).</p> <p>The British Geological Survey thin-sheet surface electric field model was used together with our magnetometer measurements to calculate electric fields and geomagnetically induced currents (GICs) in the Irish power grid.</p> <p>Although it was one of the most magnetically disturbed days in a decade, with dB/dt reaching ~50 nT/min, the peak GIC level estimated in the Irish power grid was ~10 Amps. Note, no adverse effects were reported in the Irish power grid demonstrating its resilience to geomagnetic storms of this magnitude.</p
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