556,116 research outputs found

    Civil War and Globalization: The Effect of Colonialism on Political Globalization

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    The purpose of this paper to determine why civil war onset reduces political globalization in former British colonies. Through linear regression and logistic regression analyses, I test the affect of civil war onset and the presence of civil war on political globalization, controlling for former British colonies, French colonies, and other factors. More important, however, is the history behind British colonialism. Through setting up a unique institutional system and maintaining ties to its former colonies, the British have created an atmosphere conducive to international political engagement after the onset of civil war. This study shows that while civil war onset creates an immediate backlash in former British colonies, these same states actually increase their political globalization as the duration of conflict continues

    Bumblebees gain fitness through learning

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    Despite the widespread assumption that the learning abilities of animals are adapted to the particular environments in which they operate, the quantitative effects of learning performance on fitness remain virtually unknown. Here we evaluate the learning performance of bumblebees (_Bombus terrestris_) from multiple colonies in an ecologically relevant associative learning task under laboratory conditions, before testing the foraging performance of the same colonies under the field conditions. We demonstrate that variation in learning speed among bumblebee colonies is directly correlated with foraging performance, a robust fitness measure, under natural conditions. Colonies vary in learning speed by a factor of nearly 5, with the slowest learning colonies collecting 40% less nectar than the fastest learning colonies. Such a steep fitness function suggests strong selection for higher learning speed in bumblebees. Demonstrating the adaptive value of differences in learning performance under the real conditions in which animals function represents a major step towards understanding how cognitive abilities of animals are tuned to their environment

    Coercion Gone Wrong: Colonial Response to the Boston Port Act

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    On March 25, 1774, the British Parliament passed the Boston Port Act, closing Boston Harbor to commerce. The act was meant to force Boston into paying for tea dumped into the harbor four months earlier during the Boston Tea Party. Parliament believed that the colonies would not support Boston and it would be only a short time before Boston acquiesced and paid for the tea, reestablishing British authority in the colonies.1 They could not have been more wrong. The thirteen colonies were deeply disturbed by the Boston Port Act, and came together in a way that shocked Parliament. Rather than separating Boston from the rest of the colonies, the Boston Port Act ignited all of the colonies into anti-British actions

    Porites superfusa mortality and recovery from a bleaching event at Palmyra Atoll, USA.

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    BackgroundThe demography of a coral colony is not a binary trajectory of life and death. Based on the flexibility afforded by colonial organization, most reef-building corals employ a variety of dynamic survival strategies, including growth and shrinkage. The demographic flexibility affects coral size, shape and reproductive output, among other factors. It is thus critical to quantify the relative importance of key dynamics of recruitment, mortality, growth and shrinkage in changing the overall cover of coral on a reef.MethodsUsing fixed photographic quadrats, we tracked the patterns of change in the cover of one common central Pacific coral, Porites superfusa, before and after the 2009 ENSO event.ResultsCoral colonies suffered both whole and partial colony mortality, although larger colonies were more likely to survive. In subsequent years, recruitment of new colonies and regrowth of surviving colonies both contributed to the modest recovery of P. superfusa.DiscussionThis study is unique in its quantitative comparisons of coral recruitment versus regrowth during periods of areal expansion. Our data suggest that recovery is not limited simply to the long pathway of settlement, recruitment and early growth of new colonies but is accelerated by means of regrowth of already established colonies having suffered partial mortality

    Quantification of the morphological characteristics of hESC colonies

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    The maintenance of the pluripotent state in human embryonic stem cells (hESCs) is critical for further application in regenerative medicine, drug testing and studies of fundamental biology. Currently, the selection of the best quality cells and colonies for propagation is typically performed by eye, in terms of the displayed morphological features, such as prominent/abundant nucleoli and a colony with a tightly packed appearance and a well-defined edge. Using image analysis and computational tools, we precisely quantify these properties using phase-contrast images of hESC colonies of different sizes (0.1 -- 1.1mm2\, \text{mm}^2) during days 2, 3 and 4 after plating. Our analyses reveal noticeable differences in their structure influenced directly by the colony area AA. Large colonies (A>0.6mm2A > 0.6 \, \text{mm}^2) have cells with smaller nuclei and a short intercellular distance when compared with small colonies (A<0.2mm2A < 0.2 \, \text{mm}^2). The gaps between the cells, which are present in small and medium sized colonies with A0.6mm2A \le 0.6 \, \text{mm}^2, disappear in large colonies (A>0.6mm2A > 0.6 \, \text{mm}^2) due to the proliferation of the cells in the bulk. This increases the colony density and the number of nearest neighbours. We also detect the self-organisation of cells in the colonies where newly divided (smallest) cells cluster together in patches, separated from larger cells at the final stages of the cell cycle. This might influence directly cell-to-cell interactions and the community effects within the colonies since the segregation induced by size differences allows the interchange of neighbours as the cells proliferate and the colony grows. Our findings are relevant to efforts to determine the quality of hESC colonies and establish colony characteristics database

    Towards integrated control of varroa: effect of variation in hygienic behaviour among honey bee colonies on mite population increase and deformed wing virus incidence

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    Hygienic behaviour in the honey bee, Apis mellifera, is the uncapping and removal of dead, diseased or infected brood from sealed cells by worker bees. We determined the effect of hygienic behaviour on varroa population growth and incidence of deformed wing virus (DWV), which can be transmitted by varroa. We treated 42 broodless honey bee colonies with oxalic acid in early January 2013 to reduce varroa populations to low levels, which we quantified by extracting mites from a sample of worker bees. We quantified varroa levels, again when the colonies were broodless, 48 weeks later. During the summer the hygienic behaviour in each colony was quantified four times using the Freeze Killed Brood (FKB) removal assay, and ranged from 27.5 % to 100 %. Varroa population increased greatly over the season, and there was a significant negative correlation between varroa increase and FKB removal. This was entirely due to fully hygienic colonies with >95 % FKB having only 43 % of the varroa build up of the less hygienic colonies.None of the 14 colonies with >80 % FKB removal had overt symptoms of DWV, whilst 36 % of the less hygienic colonies did. Higher levels of FKB removal also correlated significantly with lower numbers of DWV RNA copies in worker bees, but not in varroa mites. On average, fully hygienic colonies had c. 10,000 times less viral RNA than less hygienic colonies

    Universality in Bacterial Colonies

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    The emergent spatial patterns generated by growing bacterial colonies have been the focus of intense study in physics during the last twenty years. Both experimental and theoretical investigations have made possible a clear qualitative picture of the different structures that such colonies can exhibit, depending on the medium on which they are growing. However, there are relatively few quantitative descriptions of these patterns. In this paper, we use a mechanistically detailed simulation framework to measure the scaling exponents associated with the advancing fronts of bacterial colonies on hard agar substrata, aiming to discern the universality class to which the system belongs. We show that the universal behavior exhibited by the colonies can be much richer than previously reported, and we propose the possibility of up to four different sub-phases within the medium-to-high nutrient concentration regime. We hypothesize that the quenched disorder that characterizes one of these sub-phases is an emergent property of the growth and division of bacteria competing for limited space and nutrients.Comment: 12 pages, 5 figure

    Quantification of the morphological characteristics of hESC colonies

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    The maintenance of the undifferentiated state in human embryonic stem cells (hESCs) is critical for further application in regenerative medicine, drug testing and studies of fundamental biology. Currently, the selection of the best quality cells and colonies for propagation is typically performed by eye, in terms of the displayed morphological features, such as prominent/abundant nucleoli and a colony with a tightly packed appearance and a well-defined edge. Using image analysis and computational tools, we precisely quantify these properties using phase-contrast images of hESC colonies of different sizes (0.1–1.1 mm2) during days 2, 3 and 4 after plating. Our analyses reveal noticeable differences in their structure influenced directly by the colony area A. Large colonies (A > 0.6 mm2) have cells with smaller nuclei and a short intercellular distance when compared with small colonies (A  0.6 mm2) due to the proliferation of the cells in the bulk. This increases the colony density and the number of nearest neighbours. We also detect the self-organisation of cells in the colonies where newly divided (smallest) cells cluster together in patches, separated from larger cells at the final stages of the cell cycle. This might influence directly cell-to-cell interactions and the community effects within the colonies since the segregation induced by size differences allows the interchange of neighbours as the cells proliferate and the colony grows. Our findings are relevant to efforts to determine the quality of hESC colonies and establish colony characteristics database

    Biology of \u3ci\u3eDiastrophus Nebulosus\u3c/i\u3e (Hymenoptera: Cynipidae) and Its Parasitoid/Inquiline Complex in Galls on \u3ci\u3eRubus Flagellaris\u3c/i\u3e (Rosaceae)

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    Rubus flagellaris patches occasionally harbor colonies of compound stem- galls initiated by the cynipid, Diastrophus nebulosus. These isolated colonies host a parasitoid/inquiline complex made up of five principal and three incidental chalcidoid species and one cynipid inquiline. Over 1-2 seasons, parasitoid/inquiline infestation reduced primary host populations to lows of 2-0% in some colonies. Despite heavy parasitism in most colonies, dispersal of D. nebulosus out of infested colonies resulted in a survival rate of 22%. Among parasitoids, a new species, Eurytoma rubrigalla, was revealed along with new records for Eupelmella vesicularis and an unidentified Habrocytus species. Immature stages and life histories of D. nebulosus and members of its parasitoid/inquiline complex are illustrated and described with notes on gall genesis and development. Courtship and mating is summarized for Eurytoma diastrophi and arrhenotoky is here first reported for a Nearctic species in Diastrophus
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