848 resultados para History of Concepts. Science


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v.30 (1944-1945)

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v.41 (1960)

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v.36:pt.2 (1954)

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v.50:no.1-8 (1972-1974)

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v.48:no.1-13 (1968-1969)

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v.44 (1963)

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v 4 (1848)

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v 9 (1870)

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PURPOSE OF REVIEW: An improved understanding of how recombination affects the evolutionary history of HIV is crucial to understand its current and future evolution. The present review aims to disentangle the manifold effects of recombination on HIV by discussing its effects on the evolutionary history and the adaptive potential of HIV in the context of concepts from evolutionary genetics and genomics. RECENT FINDINGS: The increasing occurrence of secondary contacts between divergent subtype populations (during coinfection) results in increased observations of recombinants worldwide. Recombination is heterogeneous along the HIV genome. Consequences of recombination of HIV evolution are, in combination with other demographic processes, expected to either homogenize the genetic composition of HIV populations (homogenization) or provide the potential for novel adaptations (diversification). New methods in population genomics allow deep characterization of recombinant genome (the segment composition and origin) and their evolutionary trajectories. SUMMARY: HIV recombinants increase worldwide and invade geographical regions where pure subtypes were previously predominant. This trend is expected to continue in the future, as ease to travel worldwide increases opportunities for recombination between divergent HIV strains. While the effects of recombination in HIV are much researched, more effort is required to characterize current HIV recombinant composition and dynamics. This can be achieved with new population genetic and genomic methods.

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The fire ant Solenopsis invicta is a significant pest that was inadvertently introduced into the southern United States almost a century ago and more recently into California and other regions of the world. An assessment of genetic variation at a diverse set of molecular markers in 2144 fire ant colonies from 75 geographic sites worldwide revealed that at least nine separate introductions of S. invicta have occurred into newly invaded areas and that the main southern U.S. population is probably the source of all but one of these introductions. The sole exception involves a putative serial invasion from the southern United States to California to Taiwan. These results illustrate in stark fashion a severe negative consequence of an increasingly massive and interconnected global trade and travel system.

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Over the past two decades, soil ecotoxicologists have made strides in utilizing the basic concepts and advancements in soil zoology and ecology. They have applied the existing tools, and developed new ones to investigate how chemical contamination can affect soil ecosystems, including the degradation or destruction of soil quality and habitats or the diminishment of belowground biodiversity. Soil ecotoxicologists are applying a suite of standard protocols, originally developed as laboratory tests with single chemicals (e.g., pesticides), and further enhancing both the approaches and protocols for the assessment of contaminated lands. However, ecological relevance of some approaches remains unresolved. The authors discuss the main challenges for a coherent ecotoxicological assessment of soil ecosystems amid contaminated lands, and provide recommendations on how to integrate the effects of physical and chemical soil properties, the variations in the diversity of soil invertebrates, and the interactions among organisms of various trophic levels. The review examines new international approaches and test methods using examples from three continents (in particular research conducted in Brazil), and provides recommendations for improving ecological relevance of ecotoxicological investigations of contaminated lands.

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The formulation of the so-called law of rectilinear diameter for the determination of the critical volume of substances in the concluding decades of the nineteenth century became in a very useful and acceptably exact alternative tool for researchers in the field of critical phenomena. Its corresponding original expression, and even those of its early few modifications, were so mathematically simple that their use did not limit to exclusively contribute to remove the by then experimental obstacle for the estimating of this critical parameter, but also extended along several decades in the increasing applications of the principle of corresponding states.

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The emergence of the idea of multiculturalism in Swedish public discourse and social science in the latter half of the 1960s and introduction of official multiculturalism in 1975 constituted a major intellectual and political shift in the post-war history of Sweden. The ambition of the 1975 immigrant and minority policy to enable the preservation of ethno-cultural minorities and to create a positive attitude towards the new multicultural society among the majority population was also incorporated into Swedish cultural, educational and media policies. The rejection of assimilationism and the new commitment to ethno-cultural diversity, the multicultural moment, has earned Sweden a place on the list of the early adopters of official multiculturalism, together with Canada and Australia. This compilation thesis examines the origins and early post-war history of the idea of multiculturalism as well as the interplay between idea and politics in the shift from a public ideal of homogeneity to an ideal of multiculturalism in Sweden. It does so from a range of conceptual, comparative, transnational, and biographical perspectives. The thesis consists of an introduction (Part I) and four previously published studies (Part II). The primary research result of the thesis concerns the agency involved in the break-through and formal establishment of the idea of multiculturalism in Sweden. Actors such as ethnic activists, experts and officials were instrumental in the introduction and establishment of multiculturalism in Sweden, as they also had been in Canada and in Australia. These actors have, however, not previously been recognized and analysed as significant idea-makers and political agents in the case of Sweden. The intertwined connections between activists, social scientists, linguists, and officials facilitated the transfer of the idea of multiculturalism from a publically contested idea to public policy via the way of The Swedish Trade Union Confederation, academia and the Royal Commission of Immigration. The thesis furthermore shows that the political success of the idea of multiculturalism, such as it was within the limits of the universalist social democratic welfare state, was dependent on whom the claims-makers were, the status and positions they held, and the way the idea of multiculturalism was conceptualised and used. It was also dependent on the migratory context of labour immigration in the 1960s and 1970s and on whose behalf the advocates of multiculturalism made their claims. The majority of the labour immigrants were Finnish citizens from the former eastern half of the kingdom of Sweden who were net contributors to the Swedish welfare state. This facilitated the recognition of their ethno-cultural difference, and, following the logic of universalism, the ethno-cultural difference of other minority groups in Sweden. The historical significance of the multicultural moment is still evident in the contemporary immigration and integration policies of Sweden. The affirmation of diversity continues to set Sweden apart from the rest of Europe, now more so than in the 1970s, even though the migratory context has changed radically in the last 40 years.

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Herodotus' logos represents many examples ofthe relationship between political and paradigmatic authority, and the synthesis ofthese examples in a community characterized by free and equal speech. Herodotus' walkabout narrator sets forth an inquiry into knowledge-seeking he extends the isegoria principle from Athenian politics to the broader world. The History demonstrates (a) various modes of constructing meaning, (b) interacting notions ofhow people have lived and living questions as to how we ought to live, and (c) an investigation ofthe nature and limits ofhuman knowledge. Representing diverse wisdom, publicly and privately discovered and presented, Herodotus sets forth Solon's wise advice and law-making, the capital punishment of the learned Anacharsis, the investigative outrages of Cambyses and Psammetichus' more pious experiments. Their stories challenge and complement their communities' characters - the relative constraint under which the Egyptians and Persians make their investigations, the Scythians' qualified openness and the relative fearlessness and freedom in which the Greeks set forth their inquiries. Setting forth the investigator-storykeeper as a poetic historian, Herodotus shows that history as poetry thwarts natural decay by allowing custom to be reformed in an open milieu, and thus win through and survive. Despite the potential dangers that openness shares with tyranny, Herodotus' inquiry sets up a contest ofworld-views in which it is mutability that openness affords a community that ensures its survival.