520 research outputs found

    The separation of some inorganic compounds by liquid-liquid extraction

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    A countercurrent liquid-liquid extractor

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    A novel countercurrent liquid-liquid extractor is presented and illustrated with applications. The apparatus consists essentially of an assembly of mixer-settlers, feeders, reservoirs, and flow lines that are made of glass or other chemical resistant materials. In operation this multistage assembly rotates intermittently in one direction on a horizontal axis causing the immiscible phases to progress to opposite ends of the unit. Details for the construction of the extractor and its principles of operation are given. Extractors of this design are applicable to experimental work and to the preparation of pure compounds in quantity

    Separations of yttrium and some rare earths by liquid-liquid extraction

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    The use of liquid-liquid extraction for the separation of some inorganic compounds was demonstrated

    Application of liquid-liquid extraction for the separation of zirconium from hafnium

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    The use of liquid-liquid extraction for the separation of zirconium from hafnium was demonstrated. Hafnium spectrographically free of zirconium was prepared in quantity on a continuous basis. High purity fractions of zirconium were also prepared

    All in the Family: Partisan Disagreement and Electoral Mobilization in Intimate Networks - a Spillover Experiment

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    We advance the debate about the impact of political disagreement in social networks on electoral participation by addressing issues of causal inference common in network studies, focusing on voters' most important context of interpersonal influence: the household. We leverage a randomly assigned spillover experiment conducted in the United Kingdom, combined with a detailed database of pretreatment party preferences and public turnout records, to identify social influence within heterogeneous and homogeneous partisan households. Our results show that intrahousehold mobilization effects are larger as a result of campaign contact in heterogeneous than in homogeneous partisan households, and larger still when the partisan intensity of the message is exogenously increased, suggesting discussion rather than behavioral contagion as a mechanism. Our results qualify findings from influential observational studies and suggest that within intimate social networks, negative correlations between political heterogeneity and electoral participation are unlikely to result from political disagreement

    The role of partisan cues in voter mobilization campaigns: evidence from a randomized field experiment

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    The transmission of partisan appeals during election campaigns is widely believed to aid the formation of citizens' candidate preferences, or to serve as rallying cries, thereby increasing turnout. While laboratory and survey experiments show that partisan cues help citizens decide between candidates, and partisan elections see higher turnout than non-partisan elections, it is unclear if party labels and partisan rhetoric cause voters to turn out in higher numbers in real-world elections. We exploit a low-information election in the UK to randomly assign whether campaign phone messages include strong partisan cues or promote the same candidate without such cues. Whereas we find no significant difference in the overall effectiveness of messages with and without partisan cues at increasing turnout, the effectiveness of the former is moderated by party preference: Consistent with the use of acceptance-rejection heuristics, campaign calls with partisan cues are more likely to mobilize party supporters than rival partisans

    The influence of emotional cues on prospective memory: A systematic review with meta-analyses

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    Remembering to perform a behaviour in the future, prospective memory, is essential to ensuring that people fulfil their intentions. Prospective memory involves committing to memory a cue to action (encoding), and later recognising and acting upon the cue in the environment (retrieval). Prospective memory performance is believed to be influenced by the emotionality of the cues, however the literature is fragmented and inconsistent. We conducted a systematic search to synthesise research on the influence of emotion on prospective memory. Sixty-seven effect sizes were extracted from 17 articles and hypothesised effects tested using three meta-analyses. Overall, prospective memory was enhanced when positively-valenced rather than neutral cues were presented (d = 0.32). In contrast, negatively-valenced cues did not enhance prospective memory overall (d = 0.07), but this effect was moderated by the timing of the emotional manipulation. Prospective memory performance was improved when negatively-valenced cues were presented during both encoding and retrieval (d = 0.40), but undermined when presented only during encoding (d = -0.25). Moderating effects were also found for cue-focality and whether studies controlled for the arousal level of the cues. The principal finding is that positively-valenced cues improve prospective memory performance and that timing of the manipulation can moderate emotional effects on prospective memory. We offer a new agenda for future empirical work and theorising in this area

    Students benefit from developing their own emergency medicine OSCE stations: a comparative study using the matched-pair method

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    Background: Students can improve the learning process by developing their own multiple choice questions. If a similar effect occurred when creating OSCE (objective structured clinical examination) stations by themselves it could be beneficial to involve them in the development of OSCE stations. This study investigates the effect of students developing emergency medicine OSCE stations on their test performance. Method: In the 2011/12 winter semester, an emergency medicine OSCE was held for the first time at the Faculty of Medicine at the University of Leipzig. When preparing for the OSCE, 13 students (the intervention group) developed and tested emergency medicine examination stations as a learning experience. Their subsequent OSCE performance was compared to that of 13 other students (the control group), who were parallelized in terms of age, gender, semester and level of previous knowledge using the matched-pair method. In addition, both groups were compared to 20 students who tested the OSCE prior to regular emergency medicine training (test OSCE group). Results: There were no differences between the three groups regarding age (24.3 +/- 2.6; 24.2 +/- 3.4 and 24 +/- 2.3 years) or previous knowledge (29.3 +/- 3.4; 29.3 +/- 3.2 and 28.9 +/- 4.7 points in the multiple choice {[} MC] exam in emergency medicine). Merely the gender distribution differed (8 female and 5 male students in the intervention and control group vs. 3 males and 17 females in the test OSCE group). In the exam OSCE, participants in the intervention group scored 233.4 +/- 6.3 points (mean +/- SD) compared to 223.8 +/- 9.2 points (p < 0.01) in the control group. Cohen's effect size was d = 1.24. The students of the test OSCE group scored 223.2 +/- 13.4 points. Conclusions: Students who actively develop OSCE stations when preparing for an emergency medicine OSCE achieve better exam results
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