2,721 research outputs found

    In the attraction, compromise, and similarity effects, alternatives are repeatedly compared in pairs on single dimensions

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    In multi-alternative choice, the attraction, compromise, and similarity effects demonstrate that the value of an alternative is not independent of the other alternatives in the choice-set. Rather, these effects suggest that a choice is reached through the comparison of alternatives. We investigated exactly how alternatives are compared against each other using eye-movement data. The results indicate that a series of comparisons is made in each choice, with a pair of alternatives compared on a single attribute dimension in each comparison. We conclude that psychological models of choice should be based on these single-attribute pairwise comparisons

    Aurore, l’enfant martyre. Essai sur la violence faite aux enfants

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    Ressortir de la petite histoire rĂ©cente du QuĂ©bec rural ce drame-symbole de l'enfant martyre que fut Aurore Gagnon : cela n'est pas sans provoquer, dans une perspective systĂ©mique en tout cas, des rĂ©flexions et une mise en perspective qui vont bien au-delĂ  des gĂ©nĂ©ralitĂ©s auxquelles ce genre de rĂ©cit donne habituellement lieu. On voit bien, par exemple, que le comportement de la belle-mĂšre d'Aurore, pour aberrant qu'il soit, n'en est pas moins surdĂ©terminĂ© par un ensemble de circonstances du milieu. Les conditions sociales d'aujourd'hui ne ressemblent guĂšre Ă  celles de naguĂšre ; il n'empĂȘche que, certains facteurs Ă©tant rĂ©unis, les enfants, qui sont pourtant notre bien le plus prĂ©cieux, continuent d'ĂȘtre en danger en prĂ©sence de leurs propres parents.This article draws on the sad story of Aurore Gagnon, a battered child raised in rural QuĂ©bec and whose turmoil was dramatized on film. By elaborating on this symbol, the author is able to generate, at least in a systemic perspective, a number of issues and outlooks that go far beyond the generalities usually associated with this tale. For instance, there is ample evidence showing that the behaviour of Aurore's stepmother, aberrant as it may be, is largely caused by a set of environmental circumstances. Of course, today's social conditions hardly resemble those of the past. Yet, given the conjunctions of certain factors, children, who are nevertheless our most valuable asset, continue to be in danger in the presence of their very own parents

    Irish drug abusers II: their psychological characteristics.

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    This is the second in a series of 3 articles based on a study of a cohort of Irish drug abusers. This article attempts to identify the psychological traits of drug abusers within the cohort. The cohort consists of 100 drug abusers who attend a drug advisory and treatment centre in Dublin for the first time between November 1977 and February 1979. Three psychosocial, scales (GEFT, NSQ, and PFS) were administered to each subject. Overall, the results indicate that subjects who participated in the study, while of average or above average intelligence, were poorly psychologically adjusted, characterised by a poor sense of identity, a high level of suggestibility and a tendency towards emotional dependence. Their overall level of intelligence was within or above the normal range

    A structure-function based approach to floc hierarchy and evidence for the non-fractal nature of natural sediment flocs

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    Abstract Natural sediment flocs are fragile, highly irregular, loosely bound aggregates comprising minerogenic and organic material. They contribute a major component of suspended sediment load and are critical for the fate and flux of sediment, carbon and pollutants in aquatic environments. Understanding their behaviour is essential to the sustainable management of waterways, fisheries and marine industries. For several decades, modelling approaches have utilised fractal mathematics and observations of two dimensional (2D) floc size distributions to infer levels of aggregation and predict their behaviour. Whilst this is a computationally simple solution, it is highly unlikely to reflect the complexity of natural sediment flocs and current models predicting fine sediment hydrodynamics are not efficient. Here, we show how new observations of fragile floc structures in three dimensions (3D) demonstrate unequivocally that natural flocs are non-fractal. We propose that floc hierarchy is based on observations of 3D structure and function rather than 2D size distribution. In contrast to fractal theory, our data indicate that flocs possess characteristics of emergent systems including non-linearity and scale-dependent feedbacks. These concepts and new data to quantify floc structures offer the opportunity to explore new emergence-based floc frameworks which better represent natural floc behaviour and could advance our predictive capacity

    Response of glacier flow and structure to proglacial lake development and climate at Fjallsjökull, south-east Iceland

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    ABSTRACTOver recent decades, the number of outlet glaciers terminating in lakes in Iceland has increased in line with climate warming. The mass-balance changes of these lake-terminating outlet glaciers are sensitive to rising air temperatures, due to altered glacier dynamics and increased surface melt. This study aims to better understand the relationship between proglacial lake development, climate, glacier dynamics and glacier structure at Fjallsjökull, a large, lake-terminating outlet glacier in south-east Iceland. We used satellite imagery to map glacier terminus position and lake extent between 1973 and 2016, and a combination of aerial and satellite imagery to map the structural architecture of the glacier's terminus in 1982, 1994 and 2011. The temporal evolution of ice surface velocities between 1990 and 2018 was calculated using feature tracking. Statistically significant increases in the rate of terminus retreat and lake expansion were identified in 2001, 2009 and 2011. Our surface velocity and structural datasets revealed the development of localised flow ‘corridors’ over time, which conveyed relatively faster flow towards the glacier's terminus. We attribute the overall changes in dynamics and structural architecture at Fjallsjökull to rising air temperatures, but argue that the spatial complexities are driven by glacier specific factors, such as basal topography.</jats:p

    A comparison of human chorionic gonadotropin and luteinizing hormone releasing hormone on the induction of spermiation and amplexus in the American toad (Anaxyrus americanus).

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    BACKGROUND: Captive breeding programs for endangered amphibian species often utilize exogenous hormones for species that are difficult to breed. The purpose of our study was to compare the efficacy of two different hormones at various concentrations on sperm production, quantity and quality over time in order to optimize assisted breeding. METHODS: Male American toads (Anaxyrus americanus) were divided into three separate treatment groups, with animals in each group rotated through different concentrations of luteinizing hormone releasing hormone analog (LHRH; 0.1, 1.0, 4.0 and 32 micrograms/toad), human chorionic gonadotropin (hCG; 50, 100, 200, and 300 IU), or the control over 24 hours. We evaluated the number of males that respond by producing spermic urine, the sperm concentration, percent motility, and quality of forward progression. We also evaluated the effects of hCG and LHRH on reproductive behavior as assessed by amplexus. Data were analyzed using the Generalized Estimating Equations incorporating repeated measures over time and including the main effects of treatment and time, and the treatment by time interaction. RESULTS: The hormone hCG was significantly more effective at stimulating spermiation in male Anaxyrus americanus than LHRH and showed a dose-dependent response in the number of animals producing sperm. At the most effective hCG dose (300 IU), 100% of the male toads produced sperm, compared to only 35% for the best LHRH dose tested (4.0 micrograms). In addition to having a greater number of responders (P < 0.05), the 300 IU hCG treatment group had a much higher average sperm concentration (P < 0.05) than the treatment group receiving 4.0 micrograms LHRH. In contrast, these two treatments did not result in significant differences in sperm motility or quality of forward progressive motility. However, more males went into amplexus when treated with LHRH vs. hCG (90% vs. 75%) by nine hours post-administration. CONCLUSION: There is a clear dichotomy between the two hormones' physiological responses on gamete production and stimulation of amplexus. Understanding how these two hormones influence physiology and reproductive behaviors in amphibians will have direct bearing on establishing similar breeding protocols for endangered species

    The importance of particle dispersion in electrical treeing and breakdown in nano-filled epoxy resin

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    The addition of nano-fillers has been widely proposed as a method to enhance the dielectric properties of high voltage polymeric insulation, though there are mixed reports in the literature. Here the potential of silica nano-particles to extend the time to failure specifically through resistance to electrical tree growth in epoxy resin is determined. The benefit of silane treating the nano-particles before compounding is clearly established with regard to slowing tree growth and subsequent time to failure. The growth of trees in needle-plane samples is measured in the laboratory with loadings of 1, 3 and 5 wt% nano-filler. In all cases the average times to failure are extended, but silane treatment of the nano-particles prior to compounding yields much superior results. The emergence of a pronounced inception time before tree growth is also noted for the higher-filled, silane-treated cases. The average time to failure of silane-treated 5 wt% filled material was 28 times that of the unfilled resin. The improvement in performance between the nanocomposites with untreated and treated fillers is attributed to fewer agglomerations and improved dispersion of the filler in the treated cases. Measurements of Partial Discharge (PD) indicated significant differences in PD patterns during the growth of trees in the treated and untreated cases. This distinction may provide a quality control method for monitoring materials. In particular, long periods in which PDs were not measured were observed in the silane-treated cases. Visual imaging of tree growth in the unfilled material allowed the changing nature of the tree from fine to tree to dark tree to be observed as it grew. Corresponding PD measurements suggest the dark tree is gradually becoming conductive, and that growth of maximum PD measured is dependent on the relative rates of the growth of the tree and its carbonization. X-ray computer tomography identified significant differences in average tree channel diameters (a reduction from 2.8 ”m to 2.0 ”m for 1 wt% and 3 wt% cases). This implies that in addition to tree length changes, evaporated tree volumes also change and may explain the change in partial discharge characteristics observed

    Experimentally Validated Analytical Model of a Semi-active Resettable Tendon for Seismic Protection

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    This paper describes the development of a numerical model to predict the behaviour of a semi-active resettable tendon during seismic testing. Two resettable tendons were installed as lateral bracings in a four-storey one-fifth scale structure to reduce its seismic response. The test structure was subjected to different simulated earthquake ground motions at various peak ground accelerations. Different control configurations for the resettable tendon were used to test the one-fifth scale structure on the shaking table. The analytical model has three primary components: a resettable device, a steel tendon and a steel restraint. Assumptions adopted for the analytical modelling of the semi-active resettable tendon are described. Nonlinear dynamic analyses were performed to assess the accuracy of the mathematical model. Displacement time-histories at the third floor of the test structure are used to compare the analytical and experimental results. It is shown that the analytical simulations can closely reproduce the experimentally observed behaviour of the structure
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