2,356 research outputs found

    Solidarity that cuts across racial and gender lines: reflections upon the Grunwick strike

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    Looking back at the Grunwick strike of 1976-78, Wayne Medford explains how ideas of solidarity and common good brought together a diverse group of people to support the rights of the striking workers, the majority of them immigrants. Forty years on and a time when intolerance is rising, the memories of Grunwick are vital

    Using Cleaved Amplified Polymorphic Sequence (CAPS) Genetic Markers to Determine the Extent of Hybridization between Castilleja affinis and Castilleja mollis as a Mechanism for Adapting to Climate Change on Santa Rosa Island

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    Hybridization, the process of interbreeding between individuals of different species, is one method by which plants and animals adapt to a changing environment. One example of such adaptation through hybridization may be occurring on the California Channel Islands with two species of Castilleja. While United State Geological Survey (USGS) researchers have been studying the populations of Castilleja affinis and Castilleja mollis to determine if hybridization is occurring on Santa Rosa Island since the early 1990s, up until this point primarily overt phenotypic characteristics have been used to differentiate between the two species. Genetic methods of differentiation were adopted to confirm that hybridization is in fact occurring on the island, possibly in response to climate change. Hybrids may be expanding into areas once occupied by pure C. mollis, because they might carry some of C. affinis’ traits like an ability to survive warmer, drier climates as parts of the island are starting to become warmer and drier. In this study, I have developed a cleaved amplified polymorphic sequences (CAPS) marker based on internal transcribed spacer (ITS) regions to differentiate between the two species and hybrids and have applied these CAPS markers to genotype DNA samples isolated from 132 individuals. This protocol was used to determine the extent of hybridization on Santa Rosa Island in conjunction with ongoing surveys conducted by the USGS. Work focused on genotyping previously collected samples from two main sites on the island, which allowed confirmation that patterns observed based on phenotype in the field are supported by genetic data. In the future, findings will link genetic type with survivorship and growth data, to test whether hybrids perform differently than pure C. mollis. Broadly, this will determine if the two species are in fact hybridizing as a method for adapting to climate change, the most severe threat to Channel Island biodiversity

    Best Practice Life Expectancy:An Extreme value Approach

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    <b>Background</b>: Whereas the rise in human life expectancy has been extensively studied, the evolution of maximum life expectancies, i.e., the rise in best-practice life expectancy in a group of populations, has not been examined to the same extent. The linear rise in best-practice life expectancy has been reported previously by various authors. Though remarkable, this is simply an empirical observation. <b>Objective</b>: We examine best-practice life expectancy more formally by using extreme value theory. <b>Methods</b>: Extreme value distributions are fit to the time series (1900 to 2012) of maximum life expectancies at birth and age 65, for both sexes, using data from the Human Mortality Database and the United Nations. <b>Conclusions</b>: Generalized extreme value distributions offer a theoretically justified way to model best-practice life expectancies. Using this framework one can straightforwardly obtain probability estimates of best-practice life expectancy levels or make projections about future maximum life expectancy. <b>Comments</b>: Our findings may be useful for policymakers and insurance/pension analysts who would like to obtain estimates and probabilities of future maximum life expectancies

    Holocene Glacial History of Renland, East Greenland Reconstructed From Lake Sediments

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    The Arctic is responding to the modern increase in temperature, resulting in ice loss and consequent sea-level rise. In order to understand present-day changes, we need to understand how the Arctic has reacted in the past to natural variations in climate forcing. To begin to identify the mechanisms behind climate change, I produced a Holocene glacial and climate record for the Renland Ice Cap, Scoresby Sund, East Greenland, from sediments in glacially fed lakes. I cored Rapids and Bunny Lakes, which are fed by meltwater from the Renland Ice Cap, as well as Raven Lake, which does not receive glacial influx at present. The presence or absence of glacial sediments in Rapids and Bunny Lakes gives information on the size of the Renland Ice Cap. I studied multiple sediment characteristics in the cores, including magnetic susceptibility (MS), grain size, organic and carbonate content, and color intensity. In general, I identified glacial sediment as grey, inorganic, and with high MS. Non-glacial material was black or brown with high organic content and low MS. Chronology for the cores came from radiocarbon dating of macrofossils and sieved organic fragments. My results suggest that the region may have deglaciated as early as ~12.5 ka. The high organic content in all three lakes suggests that the early- to mid-Holocene was warm with periods of limited ice extent, consistent with the Holocene thermal maximum, which has been documented elsewhere. After this warmth, the area cooled during the Neoglaciation that culminated in the largest glacial event of the Holocene during the Little Ice Age. Superimposed on the long-term climate change were multiple centennial-to-millennial-scale glacial advances at ~ 9.4, 8.6-8.8, 8.1-8.3, 7.6-7.8, 7.0-7.5, 5.8-6.0, 4.7-5.0, 3.7-4.0, 3.0-3.6, and ~1.0 (AD 600 and 900) cal. kyBP. My reconstruction of variations in the Renland Ice Cap matches well with other glacial records from Scoresby Sund and from the wider Northern Hemisphere. In addition, comparison with other glacial records from the Scoresby Sund region suggests that elevation exerts a strong control on the timing, size, and number of glacial advances exhibited at each site. This highlights the need for caution when comparing glacial records from large geographic areas. The Renland record, along with other Northern Hemisphere data, indicates pervasive millennial-scale climate change throughout the Holocene, with the largest magnitude glacial advance occurring during the Little Ice Age. This pattern favors a cyclical forcing mechanism, such as solar variability or a \u27wobbly ocean conveyor,\u27 rather than unique events, such as volcanic eruptions or outburst floods, as a cause of millennial-scale climate change

    The Detection of Morphological Variation across Time in Two Roan Mountain Endemics: \u3cem\u3eGeum radiatum\u3c/em\u3e and \u3cem\u3eHoustonia montana\u3c/em\u3e.

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    Morphological variation between geographically distant populations has long been recognized. The primary objective of this study was to test whether nonrandom shifts in morphology have occurred across a 150-year time span in two rare, endangered plant species Geum radiatum and Houstonia montana. During the last century the vegetation on Roan Mountain has undergone numerous environmental pressures that may have produced morphological shifts. A diverse suite of morphological characters was measured from both species. Characters included vegetative and reproductive structures. Herbarium specimens and direct field measurements were the sources of material used. Results indicated a significant increase in size across time in the majority of characters measured. Results of this study challenge standard taxonomic practices, present questions pertaining to the relationship between genetics and morphology, and raise issues concerning conservation and management strategies of endangered plant populations
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