999 resultados para island fragmentation


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The fasting metabolism of 71- to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups from Amsterdam Island, southern Indian Ocean, was investigated during the long foraging trips of their mothers. Body lipid reserves were proportionally greater in female than male pups and higher in postmoult (37%) than premoult (10%) animals. The mass-specific rate of mass loss did not differ between the sexes but was lower than observed in other species. Daily mass loss was estimated to 56% fat, 10% protein, and 34% water. The rate of protein catabolism (15 g d−1) was negatively related to the size of initial lipid stores and accounted for 9% (±1%) of total energy expenditure. However, body composition changes during the fast were not equal between the sexes, with females relying more on protein catabolism than males (11% and 5% of total energy expenditure, respectively). Energy expenditure (270 kJ kg−1 d−1) and metabolic water production (11.5 mL kg−1 d−1) rates are the lowest reported for an otariid species. These results suggest that subantarctic fur seal pups greatly reduce activity levels to lower energy expenditure in addition to adopting protein-sparing metabolic pathways in order to survive the extreme fasts they must endure on Amsterdam Island.

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This study investigates the urban heat island effect in Singapore and examines the key factors causing this effect. The possibilities of improving heat extraction rate by optimizing air flow in selected hot spots were explored. The effect of building geometry, façade materials and the location of air-conditioning condensers on the outdoor air temperature was explored using computational fluid dynamics (CFD) simulations. It was found that at very low wind speeds, the effect of façade materials and their colours was very significant and the temperature at the middle of a narrow canyon increased up to 2.5 °C with the façade material having lower albedo. It was also found that strategically placing a few high-rise towers will enhance the air flow inside the canyon thereby reducing the air temperature. Adopting an optimum H/W ratio for the canyons increased the velocity by up to 35% and reduced the corresponding temperature by up to 0.7 °C.

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In this article, we consider the stability of the real effective exchange rates for four Pacific Island countries using the Lee and Strazicich (2003a, b) unit root test, which allows one to incorporate at most two structural breaks in the data series. Our main finding is that for Papua New Guinea and Samoa, exchange rates are stable, implying that shocks will have a transitory effect on real effective exchange rates, while for Fiji and the Solomon Islands we find exchange rates to be unstable, implying that shocks will have a permanent effect on real effective exchange rates.

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Simultaneously analysing demographic processes of small mammals living in different ecological contexts may help to understand mechanisms that influence the growth and decline of these populations. The size and demography of swamp antechinus (Antechinus minimus) populations located in a coastal mainland habitat and on a small offshore island in south-eastern Australia were investigated. Large demographic differences occurred between the two ecosystems, with the island population density often 100 times greater than that on the mainland. The swamp antechinus in the mainland habitat was influenced by extrinsic climatic forces, with juvenile recruitment, individual body mass and overall population size being affected by rainfall, a factor likely to influence food availability for the species. However, the island population did not appear to be affected by drought to the same degree where allochthonous marine nutrient inputs may have offset any drought-induced reduction in primary production. Significantly greater juvenile recruitment in the island habitats combined with restricted emigration and potentially reduced predation and interspecific competition are likely to be responsible for the high population densities on the island. Although island populations appear robust, future conservation efforts should focus on mainland populations given the genetic deficiencies in the island populations.

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Urban areas tend to have higher air temperatures than their surroundings as a result of man-made aiterations. This phenomenon is known as the urban heat island (UHI) effect. UHI is considered to he one of the major problems encountered by the human race this century. Solar radiation that is absorbed during the day by buildings is re~emitted after sunset creating high temperatures in urban areas. Also, anthropogenic heat sources such as air conditioners and road traffic add to the rise in temperatures, A number of
studies have indicated that UHI has a significant effect on the energy use of buildings. In mid- and low-latitude cities, heat islands contribute to urban dwellers' summer discomfort and significantly higher air-conditioning loads. This chapter summarizes and reviews the latest research methodologies and findings about the effect of increased temperatures on the energy consumption of buildings. The latest developments in the heat island mitigation strategies are remarkable, However, more attention needs to be
given to the implementation and testing of these strategies in full-scale buildings.

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The effect of the insecticide, pyriproxyfen on early ovary synthesis was examined in the Gecarcinid land crab, Gecarcoidea natalis. Crabs were fed a mixture of either leaf litter and bait containing 0.5% (wt/wt) pyriproxyfen (experimental groups), or a mixture of leaf litter and a control bait containing no pyriproxyfen (control groups), at simulated baiting doses of 2 kg ha− 1 and 4 kg ha− 1, during the period in which G. natalis synthesises its ovaries. A third group of crabs were fed ad libitum either the bait containing 0.5% Pypriproxyfen or the control bait. Pyriproxyfen affected early ovary development in G. natalis. The ovaries from crabs in the experimental groups at all baiting levels had a higher total nitrogen content and dry mass than the ovaries from crabs in the control groups. Pyriproxyfen affected the histology of the ovaries. Ovaries from animals in the experimental groups were more mature, containing more previtellogenic and early vitellogenic oocytes, of a larger diameter, than the ovaries from crabs in the control groups. Significant amounts of pyriproxyfen accumulated within the midgut gland and ovary, the hypothesised target tissues, while minor amounts of pyriproxyfen was accumulated in the muscle, a hypothesised non target tissue. Pyriproxyfen may have stimulated early ovary development and induced synthesis of yolk protein by mimicking methyl farnesoate and thus causing endocrine disruption. Given this, pyriproxyfen should not be used to control invasive insects in environments where gecarcinid and other land crab species are present.

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The works presented interrogate a world in which lies have given us a set of metaphysical problems. The works deal with time, space and surfaces working together yet disrupted.

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Social capital helps communities respond positively to change. Research in agricultural businesses and into managing change through learning in communities has highlighted the importance of relationships between people and the formal and informal infrastructure of communities to the quality of outcomes experienced by communities, businesses and individuals. Communities can be geographic communities - the data drawn on in this paper are from an island community, for example or communities-of-common-purpose, such as agricultural organisations. This paper reviews research into managing change through learning and social capital, presents a model of the simultaneous building and use of social capital and explores the ways in which learning as part of an agricultural community can be used to bring benefits to geographic communities such as islands. The model presented in this paper stems from studies of the informal learning process that builds resilient communities. It conceptualises the way in which social capital is used and built in interactions between individuals. There are two stages to the model. The first stage depicts social capital at the micro level of one-on-one interactions where it is built and used. The second stage of the model is about the interrelationship of micro-level social capital processes with the community and societal-level social capital resources.

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The study is focused on an analysis of the major diplomatic documents from the mid eighteenth century to the present as regards Sri Lanka, or Ceylon as it was known till 1972. The objectives of the study are to identify the issues underlying these diplomatic documents. These include the political and strategic factors and other subsidiary issues like trade and commerce relevant at the time these treaties, agreements, and proposed treaties were formulated. It is also a geopolitical study as it relates to Sri Lanka's geographical position in the Indian Ocean, and her possession of the Trincomalee Harbour on its east coast, which is one of the great natural harbours of the world. Over the centuries this harbour has had significant strategic value for naval deployments. The case study of the eighteenth and nineteenth centuries studies the diplomatic documents against the political and strategic background for the French Revolution and actions of Napoleon, and the Anglo/French rivalry, spreading from Europe to North America and Asia. In the twentieth century the environment for studying the place of Sri Lanka in the Indian Ocean was created by the Russian Revolution, the failure to keep the peace of Versailles after World War I, the conflict and horrors of World War II which led to the disintegration of European colonial empires in Asia and Africa, and the tensions generated by the Cold War. A study of the documents would reveal that in international relations what matters is the ability of a party to promote its interests, and this depends on its power. This realist approach contrasts to the idealist approach where policies are based on moral and ethical principles. For the realist the states should follow to protect their interests and to survive. To achieve this is to strive for a ‘balance of power’. To do so is to form a favourable alliance system. As the documents examined cover a period from the mid-eighteenth century to the later part of the twentieth century, they reflect the changing technologies that have had an influence on naval and military matters. For example, this period witnessed great changes in technology of energy utilized to propel warships, from wind, to steam, to fuel and finally to nuclear power. These changes had an influence in determining strategic policies involving weapon systems and communications within a global and regional setting. The period covered was the beginning of the process described a ‘globalisation’. Its idea is not unique to this century; there were many attempts, in various times of history, to integrate societies within a global context. Viewed in this light, the Anglo-French rivalry of the eighteenth and nineteenth centuries was the indication of a global naval strategy, in which Sri Lanka was a major factor in the Indian Ocean region. This process was associated with the phenomena called the ‘expansion of Europe’. It covered all the oceans of the world and in the nineteenth and twentieth centuries led to the founding of the largest maritime empire the world has ever seen: The British Empire. After World War I, the British naval strength (the basis of the British Empire) and her consequent position as a great power, was challenged by other powers like the United States of America and Japan. After World War II, the US Navy was supreme: and there was a close alliance between Britain and the USA. The strength of the US/British alliance was based on the navy and its bases, which were spread throughout the globe; to project power, and act as deterrence and balancing force. Sri Lanka, due to her strategic position, was a part of this evolving process, and was tied to a global strategy (with its regional connotations) from the eighteenth century to the present.