979 resultados para Colonies.
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Mode of access: Internet.
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Half-title: Colonies and colonial federations. The English citizen; his rights and responsibilities.
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Mode of access: Internet.
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Samples of the cyanobacterium Microcystis aeruginosa from a small pond were used in laboratory experiments with a grid-stirred tank to quantify the effect of turbulent mixing on colony size. Turbulent dissipation in the tank was varied from 10(-9) m(2) s(-3) to 10(-4) m(2) s(-3), covering the range of turbulence intensities experienced by M. aeruginosa colonies in the field and exceeding the maximum dissipation by two orders of magnitude. Large colonies broke up into smaller colonies during the experiments; the mass fraction of colonies with diameter less than 200 mum increased over time. Colony disaggregation was observed to increase with turbulent dissipation. The maximum stable colony diameter across all experiments was in the range 220-420 mum. The overall change in size distribution during the experiments was relatively small, and the colony size distribution remained very broad throughout the experiments. Since colony size affects migration velocity, susceptibility to grazing and surface area to volume ratios, more work is needed to determine how to best represent this broad size distribution when modelling M. aeruginosa populations.
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When Oscar Wilde was imprisoned in 1895, his plays were withdrawn from the London stage and, as Joel Kaplan and Seila Stowell note, exiled to the provinces and played with their author's name discreetly removed. Here, Fotheringham examines the impact of Wilde's trials and imprisonment throughout 1895-1897 on public reception to Brough-Boucicault Comedy Company's performances of his plays in Australia.
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The red-tailed phascogale ( Phascogale calura) is an endangered dasyurid species that has recently been brought into captivity in an effort to increase numbers before release back into the wild. As part of investigations into the reproductive biology of the species, information on the growth and development of young was collected throughout lactation from litters raised in three separate colonies. Growth curves for aging young throughout lactation and a timetable of developmental changes were constructed. While two colonies, with fourth- and fifth-generation captive animals, showed no significant difference in growth, animals from a third colony that had been wild caught before breeding displayed a slower rate of growth from 34 days of age. The pattern of development resembled that of other dasyurids, with young left in the nest from 44 days of age, fully furred by 78 days and weaned between 90 and 110 days. Captive phascogales invest heavily in their young, with litters weighing 380 +/- 67% of maternal bodyweight at weaning.
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An investigation of behavioural patterns that form a basis for termite control in the Australasian region was undertaken using laboratory colonies of the subterranean termite Reticulitermes santonensis (Feytaud). The study attempted to build a picture of the behavioural elements of individuals in a colony and based on this, trophallaxis, aggression and cannibalism were investigated in detail. Preliminary study of food transmission showed that 'workers' played a major role in the distribution of food. It was found, that among factors responsible for release of trophallactic behaviour the presence of 'right odour' between participants was important. It also appeared that the role taken by individuals depended on whether they were hungry or fully fed. Antennal palpation was shown by donors and acceptors alike and this seemed to be excitatory in function. Introduction of aliens into nests elicited aggression and these aliens were often killed. Factors eliciting aggression were investigated and colony odour was found to be important. Further investigations revealed that development of colony odour was governed by genetical and environmental mechanisms. Termite response to injury and death was also governed by odour. In the case of injury either the fresh haemolymph from the wound or some component of the haemolymph evoked cannibalism. Necrophagic behaviour was found to be released by fatty acids found in the corpses. Finally, the response of colonies to nestmates carrying arsenic trioxide was investigated. It was found that living and freshly dead arsenic-carrying nestmates were treated like normal nestmates, resulting in high initial mortality. However, poisoned cadavers soon became repellant and were buried thus preventing further spread of the poison to the rest of the colony. This suggested that complete control of subterranean termites by arsenic trioxide is unlikely to be fully effective, especially in those species which are capable of developing secondary reproductives from survivors and thus rebuilding the community.
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Richard Hooker and John Locke were important sources for the thought and public lives of Anglican leaders in the North American colonies. A conviction about religious freedom of conscience during the first half of the eighteenth century constitutes a range of thinking about toleration that contributed to the birth of the republic.
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The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata in synthetic seawater using the alkalinity anomaly technique. Changes in aragonite saturation from 98% to 585% were obtained by manipulating the calcium concentration. The results show a nonlinear increase in calcification rate as a function of aragonite saturation level. Calcification increases nearly 3-fold when aragonite saturation increases from 98% to 390%, i.e., close to the typical present saturation state of tropical seawater. There is no further increase of calcification at saturation values above this threshold. Preliminary data suggest that another coral species, Acropora sp., displays a similar behaviour. These experimental results suggest: (1) that the rate of calcification does not change significantly within the range of saturation levels corresponding to the last glacial-interglacial cycle, and (2) that it may decrease significantly in the future as a result of the decrease in the saturation level due to anthropogenic release of CO2 into the atmosphere. Experimental studies that control environmental conditions and seawater composition provide unique opportunities to unravel the response of corals to global environmental changes.