920 resultados para Climate Change: Learning from the past climate


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Although mass extinctions probably account for the disappearance of less than 5% of all extinct species, the evolutionary opportunities they have created have had a disproportionate effect on the history of life. Theoretical considerations and simulations have suggested that the empty niches created by a mass extinction should refill rapidly after extinction ameliorates. Under logistic models, this biotic rebound should be exponential, slowing as the environmental carrying capacity is approached. Empirical studies reveal a more complex dynamic, including positive feedback and an exponential growth phase during recoveries. Far from a model of refilling ecospace, mass extinctions appear to cause a collapse of ecospace, which must be rebuilt during recovery. Other generalities include the absence of a clear correlation between the magnitude of extinction and the pace of recovery or the resulting ecological and evolutionary disruption the presence of a survival interval, with few originations, immediately after an extinction and preceding the recovery phase, and the presence of many lineages that persist through an extinction event only to disappear during the subsequent recovery. Several recoveries include numerous missing lineages, groups that are found before the extinction, then latter in the recovery, but are missing during the initial survival–recovery phase. The limited biogeographic studies of recoveries suggest considerable variability between regions.

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This paper posits that the Nordic countries were able to ensure good standards of equality for its citizens, while at the same time maintaining decent levels of economic growth. This can be attributed to the Nordic countries’ more holistic approach towards social spending and their focus on uplifting the skill levels of its workforce. Thus, the notion that there must be a trade-off between economic performance and a more aggressive welfare regime should be examined more thoroughly. The debate for policy makers should perhaps be framed with regard to where the balance should be between growth and equity rather than a trade-off. Firstly, the paper will elaborate on what exactly the “Nordic model” is, based on a broad literature review. Next, the paper will unpack the key characteristics of the Nordic model and analyse if indeed expansive welfare provided through state support erodes work ethic and impact the economic competitiveness of countries. Next, the paper will provide an explanation for how the balance between economic and social objectives is maintained, in some of the Nordic countries. Lastly, the paper discusses whether the same balance can be achieved in Singapore.

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Neospora caninum is an intracellular apicomplexan parasite, which is a leading cause of abortion in cattle; thus neosporosis represents an important veterinary health problem and is of high economic significance. The parasite can infect cattle via trans-placental transmission from an infected cow to its fetus (vertical transmission), or through the oral route via ingestion of food or water contaminated with oocysts that were previously shed with the feces of a canid definitive host (horizontal transmission). Although vaccination was considered a rational strategy to prevent bovine neosporosis, the only commercialized vaccine (Neoguard®) produced ambiguous results with relatively low efficacy, and was recently removed from the market. Therefore, there is a need to develop an efficient vaccine capable of preventing both, the horizontal transmission through infected food or water to a naïve animal as well as the vertical transmission from infected but clinically asymptomatic dams to the fetus. Different vaccine strategies have been investigated, including the use of live attenuated vaccines, killed parasite lysates, total antigens or antigen fractions from killed parasites, and subunit vaccines. The vast majority of experimental studies were performed in mice, and to a certain extent in gerbils, but there is also a large number of investigations that were conducted in cattle and sheep. However, it is difficult to directly compare these studies due to the high variability of the parameters employed. In this review, we will summarize the recent advances made in vaccine development against N. caninum in cattle and in mice and highlight the most important factors, which are likely to influence the degree of protection mediated by vaccination.

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v.1. Concerning the writer. Early narrative. Under Hood and Nelson. The mutiny at the Nore. Camperdown and after. Life at the Cape. Portraits under George III. The days of Napoleon.--v.2. The days of Napoleon. Portraits after Waterloo. Portraits under George IV. Portraits under William IV. The days of Victoria.

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Mode of access: Internet.

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"A sequel to the recently published volume, Deductions from the worldwar."--p. viii.

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This paper reports on research findings from a larger study which seeks to understand leadership from the experiences of well-known and well-recognised Australian leaders across a spectrum of endeavours such as the arts, business, science, the law and politics. To date there appears to be limited empirical research that has investigated the insights of Australian leaders regarding their leadership experiences, beliefs and practices. In this paper, the leadership story of a well-respected medical scientist is discussed revealing the contextual factors that influenced her thinking about leadership as well as the key values she embodies as a leader. The paper commences by briefly considering some of the salient leadership literature in the field. In particular, two prominent theoretical frameworks provided by Leavy (2003)and Kouzes and Posner (2002) are explored. While Leavy’s framework construes leadership as consisting of three “C’s” – context , conviction and credibility, Kouzes and Posner (2002)refer to five practices of exemplary leadership. The paper provides a snapshot of the life forces and context that played an important role in shaping the leader’s views and practices. An analytical discussion of these practices is considered in the light of the earlier frameworks identified. Some implications of the findings from this non-education context for those in schools are briefly noted.