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Very Different Reasons (very + different_reason)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Massive use of chemotherapy influences life traits of parasitic nematodes in domestic ruminants

FUNCTIONAL ECOLOGY, Issue 5 2001
V. Leignel
Summary 1,The size of nematodes is an operational indicator of fecundity. The variation in size due to chemotherapy was studied with a benzimidazole anthelmintic in susceptible and resistant nematodes. Teladorsagia circumcincta circumcincta (Stadelmann 1894), a nematode endoparasite of sheep and goats, was investigated as many components of its fitness are already known. 2,Susceptible worms submitted to increasing selective pressure by anthelmintics increased in size (by 6,10%); it was hypothesized that this was partly under the control of sheep, as treated lambs may mount and maintain a better response when infected (premunition). 3,The resistant worms, whatever the anthelmintic pressure, were always 3% larger than susceptible ones. 4,Thus, size may increase in susceptible worms and resistant worms for very different reasons. If resistance does not emerge, massive chemotherapy should lead to larger nematodes, and hence to more fertile worms. [source]

Up and Down with the Agrarian Question: Issue Attention and Land Reform in Contemporary Brazil

POLITICS & POLICY, Issue 4 2008
Gabriel Ondetti
The two most recent Brazilian presidents have both surprised observers with their land reform programs but for very different reasons. Despite presiding over a center-right government with strong ties to large landowners and a state-shrinking economic program, Fernando Henrique Cardoso implemented easily the largest rural land redistribution in Brazilian history. As the leader of a leftist party and a historic champion of radical land reform, Luiz Inácio Lula da Silva seemed to have sterling pro-land reform credentials. Yet Lula's program has, by some key measures, fallen well short of Cardoso's. This article attempts to explain these two anomalous outcomes. Drawing on Downs' concept of the "issue-attention cycle," it argues that the trajectory of land reform under Cardoso and Lula largely reflects the impact of a variable rarely cited in analyses of Brazilian politics: public issue saliency. This argument holds implications for both the future of land reform in Brazil and our broader understanding of the Brazilian political system. [source]

Identifying Compact Symmetric Objects from the VLBA Imaging and Polarization Survey

ASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009
S.E. Tremblay
Abstract Compact Symmetric Objects (CSOs) are small (less than 1 kpc) radio sources which have symmetric double lobes or jets. The dominant theory for the small size of these objects is that they are young radio sources which could grow into larger radio galaxies, but the currently small population of known CSOs makes it difficult to definitively determine whether or not this is the case. While a greater number of Gigahertz peaked sources can be identified by sifting through spectral surveys, this yields none of the dynamics of the sources, and also brings Quasars into the sample, which although interesting are peaked around 1 Gigahertz for very different reasons. We have used the 5 GHz VLBA Imaging and Polarization Survey (VIPS) to identify 103 CSO candidates morphologically, and are following up on these sources with multifrequency VLBA observations to confirm CSO identifications and to study their dynamics. The identification of candidates from within the survey will be discussed, as well as preliminary results from the follow-up observations (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Climatic variability and the evolution of insect freeze tolerance

BIOLOGICAL REVIEWS, Issue 2 2003
BRENT J. SINCLAIR
ABSTRACT Insects may survive subzero temperatures by two general strategies: Freeze-tolerant insects withstand the formation of internal ice, while freeze-avoiding insects die upon freezing. While it is widely recognized that these represent alternative strategies to survive low temperatures, and mechanistic understanding of the physical and molecular process of cold tolerance are becoming well elucidated, the reasons why one strategy or the other is adopted remain unclear. Freeze avoidance is clearly basal within the arthropod lineages, and it seems that freeze tolerance has evolved convergently at least six times among the insects (in the Blattaria, Orthoptera, Coleoptera, Hymenoptera, Diptera and Lepidoptera). Of the pterygote insect species whose cold-tolerance strategy has been reported in the literature, 29% (69 of 241 species studied) of those in the Northern Hemisphere, whereas 85%(11 of 13 species) in the Southern Hemisphere exhibit freeze tolerance. A randomization test indicates that this predominance of freeze tolerance in the Southern Hemisphere is too great to be due to chance, and there is no evidence of a recent publication bias in favour of new reports of freeze-tolerant species. We conclude from this that the specific nature of cold insect habitats in the Southern Hemisphere, which are characterized by oceanic influence and climate variability must lead to strong selection in favour of freeze tolerance in this hemisphere. We envisage two main scenarios where it would prove advantageous for insects to be freeze tolerant. In the first, characteristic of cold continental habitats of the Northern Hemisphere, freeze tolerance allows insects to survive very low temperatures for long periods of time, and to avoid desiccation. These responses tend to be strongly seasonal, and insects in these habitats are only freeze tolerant for the overwintering period. By contrast, in mild and unpredictable environments, characteristic of habitats influenced by the Southern Ocean, freeze tolerance allows insects which habitually have ice nucleators in their guts to survive summer cold snaps, and to take advantage of mild winter periods without the need for extensive seasonal cold hardening. Thus, we conclude that the climates of the two hemispheres have led to the parallel evolution of freeze tolerance for very different reasons, and that this hemispheric difference is symptomatic of many wide-scale disparities in Northern and Southern ecological processes. [source]