932 resultados para happened-before


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Abstract The established protocol for the cryopreservation of winter-dormant Malus buds requires that stem explants, containing a single, dormant bud are desiccated at -4°C, for up to 14 days, to reduce their water content to 25-30% of fresh weight. Using three apple cultivars, with known differences in response to cryopreservation, the pattern of evaporative water loss has been characterised, including early freezing events in the bud and cortical tissues that allow further desiccation by water migration to extracellular ice. There were no significant differences between cultivars in this respect or in the proportions of tissue water lost during the desiccation process. Differential Scanning Calorimetry (to -90°C) of intact buds indicated that bud tissues of the cultivar with the poorest response to cryopreservation had the highest residual water content at the end of the desiccation process and froze at the highest temperature Keywords: Malus, cryopreservation, dormant bud, dehydration

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For free black women in the pre-Civil War American South, the status offered by ‘freedom’ was uncertain and malleable. The conceptualization of bondage and freedom as two diametrically opposed conditions therefore fails to make sense of the complexities of life for these women. Instead, notions of enslavement and freedom are better framed as a spectrum. This article develops this idea by exploring two of the ways in which some black women negotiated their status before the law—namely though petitioning for residency or for enslavement. While these petitions are atypical numerically, and often offer tantalizingly scant evidence, when used in conjunction with evidence from the US census, it becomes clear that these women were highly pragmatic. Prioritizing their spousal and broader familial affective relationships above their legal status, they rejected the often theoretical distinction between slavery and liberation. As such, the petitions can be used to reach broader conclusions about the attitudes of women who have left little written testimony.

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The 8.2 ka event was triggered by a meltwater pulse (MWP) into the North Atlantic and resultant reduction of the thermohaline circulation (THC). This event was preceded by a series of at least 14 MWPs; their impact on early Holocene climate has remained almost unknown. A set of high-quality paleoclimate records from across the Northern Hemisphere shows evidence for a widespread and significant climatic anomaly at ∼9.2 ka B.P. This event has climatic anomaly patterns very similar to the 8.2 ka B.P. event, cooling occurred at high latitudes and midlatitudes and drying took place in the northern tropics, and is concurrent with an MWP of considerable volume (∼8100 km3). As the 9.2 ka MWP occurs at a time of enhanced baseline freshwater flow into the North Atlantic, this MWP may have been, despite its relatively small volume, sufficient to weaken THC and to induce the observed climate anomaly pattern.

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Review essay on recent literature on the transformation of European security politics in the 1980s

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Anglo-Saxon monastic archaeology has been constrained by the limited scale of past investigations and their overriding emphasis on core buildings. This paper draws upon the results of an ongoing campaign of archaeological research that is redressing the balance through an ambitious programme of open-area excavation at Lyminge, Kent, the site of a royal double monastery founded in the seventh century ad. The results of five completed fieldwork seasons are assessed and contextualised in a narrative sequence emphasising the dynamic character of Lyminge as an Anglo-Saxon monastic settlement. In so doing, the study brings into sharp focus how early medieval monasteries were emplaced in the landscape, with specific reference to Anglo-Saxon Kent, a regional context offering key insights into how the process of monastic foundation redefined antecedent central places of long-standing politico-religious significance and social action.

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We present case studies of the evolution of magnetic wave amplitudes and auroral intensity through the late growth phase and the expansion phase of the substorm cycle. We present strong evidence that substorm-related auroral enhancements are clearly and demonstrably linked to ULF wave amplitudes observed at the same location. In most cases, we find that the highest correlations are observed when the magnetometer time series is advanced in time, indicating that the ULF wave amplitudes start to grow before measured auroral intensities, though interestingly this is not always the case. Further we discuss the four possible reasons that may be able to explain both the timing and the high correlations between these two phenomena, including: a simple coincidence, an artifact of instrumental effects, the response of the ionosphere to magnetic waves and auroral particle precipitation, and finally that ULF waves and auroral particle precipitation are physically linked. We discount coincidence and instrumental effects since in the studies presented here they are unlikely or in general will contribute negligible effects, and we find that the ionospheric response to waves and precipitation can explain some, but not all of the results contained within this paper. Specifically, ionospheric response to substorm waves and auroral precipitation cannot explain that the result that previous studies have shown, that onset of ULF wave activity and the onset of auroral particle precipitation occur at the same time and in the same location. This leaves the possibility that ULF waves and auroral particles are physically linked.

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There is a period of some 5000 years or so in the prehistory of Europe when horse populations were greatly depleted and perhaps even disappeared in many places. Before this time, during the Upper Palaeolithic, wild horses were common; after, during the Bronze Age, domestic horses were being raised and used across Europe. What happened in between is uncertain, in part because of the sketchy archaeological record. Debates continue as to the origins (the when, where and how) of Europe's domestic horses, including whether horse husbandry dispersed only from habitats favourable to horses on the Eurasian steppes or whether there was local domestication in temperate Europe. This paper reviews the evidence for the transition from wild horses to domestic horses in Europe.

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In the early 1920s, before Virginia Woolf wrote her now well-known essays “The New Biography” and “The Art of Biography,” the Hogarth Press published four biographies of Tolstoy. Each of these English translations of Russian works takes a different approach to biographical composition, and as a group they offer multiple and contradictory perspectives on Tolstoy’s character and on the genre of biography in the early twentieth century. These works show that Leonard and Virginia Woolf’s Hogarth Press took a multi-perspectival, modernist approach to publishing literary lives.