372 research outputs found

    The impacts of environmental warming on Odonata: a review

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    Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns

    The asymmetry and temporal dynamics of incidental letter-location bindings in working memory.

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    Verbal-spatial bindings are integral to routine cognitive operations (e.g., reading), yet the processes supporting them in working memory are little understood. Campo and colleagues [Campo, P., Poch, C., Parmentier, F. B. R., Moratti, S., Elsley, J. V., Castellanos, N., … Maestú, F. (2010). Oscillatory activity in prefrontal and posterior regions during implicit letter-location binding. Neuroimage, 49, 2807-2815] recently reported data suggesting obligatory letter-location binding when participants were directed to remember the letters in a display (of letters in locations), but no evidence for binding when instructed to remember the filled locations. The present study contrasted two explanations for this binding asymmetry. First, it may result from an obligatory dependence on "where" during the representation of "what" information, while "where" information may be held independently of its contents (the strong asymmetry hypothesis). Second, it may constitute a snapshot of a dynamic feature inhibition process that had partially completed by test: the asymmetrical inhibition hypothesis. Using Campo and colleagues' task with a variable retention interval between display and test, we presented four consonants in distinct locations and contrasted performance between "remember letters" and "remember locations" instructions. Our data supported the strong asymmetry hypothesis through demonstrating binding in the verbal task, but not in the spatial task. Critically, when present, verbal-spatial bindings were remarkably stable, enduring for at least 15 seconds

    The Political Economy of US Military Spending

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    The causes of the dramatic rise in military spending in the post-war era have been the subject of much political and academic controversy. No extant formulation seems to provide a compelling explanation of the dynamics involved in the levels of, and rates of change in, such spending. In light of this, the authors develop a new model, based mainly on a political-business cycle argument, to account for these dynamics. The basic proposition in this model is that variations in national defense spending arise from political considerations which are related to real and desired conditions within the national economy. Applying this model to the experience of the United States 1948-1976, the authors show that it has a large measure of empirical validity. If one removes the effects of war-time mobilization, it is clear that for the United States the principal driving forces in military spending dynamics were (1) the perceived utility of such spending in stabilizing aggregate demand, (2) the political or electoral value of the perceived economic effects arising out of such spending, and (3) the pressures of institutional-constituency demands.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68958/2/10.1177_002234337901600202.pd

    Primitive computations in speech processing

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    Previous research suggests that artificial-language learners exposed to quasi-continuous speech can learn that the first and the last syllables of words have to belong to distinct classes (e.g., Endress & Bonatti, 2007; Peña, Bonatti, Nespor, & Mehler, 2002). The mechanisms of these generalizations, however, are debated. Here we show that participants learn such generalizations only when the crucial syllables are in edge positions (i.e., the first and the last), but not when they are in medial positions (i.e., the second and the fourth in pentasyllabic items). In contrast to the generalizations, participants readily perform statistical analyses also in word middles. In analogy to sequential memory, we suggest that participants extract the generalizations using a simple but specific mechanism that encodes the positions of syllables that occur in edges. Simultaneously, they use another mechanism to track the syllable distribution in the speech streams. In contrast to previous accounts, this model explains why the generalizations are faster than the statistical computations, require additional cues, and break down under different conditions, and why they can be performed at all. We also show that that similar edge-based mechanisms may explain many results in artificial-grammar learning and also various linguistic observations
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