233 resultados para Nilpotent Group


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A migration of methyloxycarbonyl group from secondary to primary hydroxyl was observed in furanosides (ribosides and xylosides) under usual desilylation conditions using tetrabutylammonium fluoride. The migration was studied further on several alkyloxycarbonyl furanosides under either basic or acidic conditions. As follows from C labelling experiments and product distribution, the migration in xylosides, proceeds intramolecularly via six-membered cyclic carbonate, whereas in ribosides, the migration is intermolecular. Acidic conditions prevented the migration in ribosides whereas the migration in xylosides was circumvented under neutral conditions. © 2012 Elsevier Ltd. All rights reserved.

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Group transfer polymerization (GTP) chemistry was employed for the preparation of polymethacrylate networks of controlled structure (quasi-model networks) of three different types: (a) regular quasi-model networks, in which all polymer chains were linked at their ends, leaving, in principle, no free chain ends, (b) crosslinked star polymer quasi-model networks, in which star polymers were interlinked via half of their chains, letting the other half free (dangling), and (c) shell-crosslinked polymer quasi-model networks, in which the outer part of the network contained polymer arms (dangling chains). Combination of hydrophilic and hydrophobic monomers led to amphiphilic networks whose aqueous swelling behavior was characterized gravimetrically.

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The use of audience response systems (ARSs) or ‘clickers’ in higher education has increased over the recent years, predominantly owing to their ability to actively engage students, for promoting individual and group learning, and for providing instantaneous feedback to students and teachers. This paper describes how group-basedARSquizzes have been integrated into an undergraduate civil engineering course on foundation design. Overall, theARSsummary quizzes were very well received by the students. Feedback obtained from the students indicates that the majority believed the group-based quizzes were useful activities, which helped to improve their understanding of course materials, encouraged self-assessment, and assisted preparation for their summative examination. Providing students with clickers does not, however, necessarily guarantee the class will be engaged with the activity. If an ARS activity is to be successful, careful planning and design must be carried out and modifications adopted where necessary, which should be informed by the literature and relevant student feedback.

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Group work has been promoted in many countries as a key component of elementary science. However, little guidance is given as to how group work should be organised, and because previous research has seldom been conducted in authentic classrooms, its message is merely indicative. A study is reported, which attempts to address these limitations. Twenty-four classes of 10-12-year-old pupils engaged in programmes of teaching on evaporation and condensation, and force and motion. Both programmes were delivered by classroom teachers, and made extensive use of group work. Pupil understanding progressed from pre-tests prior to the programmes to post-tests afterwards, and results suggest that group work played a critical role. Organisational principles are extrapolated from the findings, which could be readily adopted in classrooms. © 2007 Elsevier Ltd. All rights reserved.

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The present study investigated the effects of a continuing professional development (CPD) initiative that provided collaborative group work skills training for primary school teachers. The study collected data from 24 primary school classrooms in different schools in a variety of urban and rural settings. The sample was composed of 332 pupils, aged 9-12 years old, and 24 primary school teachers. Results indicated that the CPD initiative had a significant impact on the attainment of pupils in science. In addition, data indicated that the CPD promoted effective discourse and pupil dialogue during science lessons. Pre-test and post-test observation scores were significantly different in terms of children giving of suggestions or courses of actions, offering of explanations, and telling someone to say something or carry out an action. Increases in effective dialogue were significantly correlated to increased science attainment, and teacher evaluations of the impact of the CPD were positive. Significant correlations were found between teacher evaluation of impact upon pupil learning and increased attainment in science. The design and structure of CPD initiatives and the implications for practice, policy and future research are explored.

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A large body of research has demonstrated the value of fostering peer interaction in the context of collaborative group work as an effective strategy to facilitate learning. The present study attempted to enable teachers in a varied sample of 24 Scottish primary classrooms to improve the quality of collaborative group work interaction among their pupils. Observations were carried out at three time points during the year of the intervention, both during whole class teaching and planned group work activity. A global rating instrument was also used to evaluate the overall quality of classroom environment created by participating class teachers to support group work sessions. The results showed significant increases both in the observed frequencies of children's collaborative dialogue and in the rated quality of classroom learning environments over the course of the study. The implications of these results are discussed in the context of current curricular reform.

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We investigated whether imagining contact with an out-group member would change behavioral tendencies toward the out-group. In Experiment 1, British high school students who imagined talking to an asylum seeker reported a stronger tendency to approach asylum seekers than did participants in a control condition. Path analysis revealed this relationship was mediated by out-group trust and, marginally, by out-group attitude. In Experiment 2, straight undergraduates who imagined an interaction with a gay individual reported a stronger tendency to approach, and a weaker tendency to avoid, gay people. Path analyses showed that these relationships were mediated by out-group trust, out-group attitude, and less intergroup anxiety. These findings highlight the potential practical importance of imagined contact and important mediators of its effects.

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The electrical conductivity of a series of pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids, functionalized with a nitrile (cyano) group at the end of an alkyl chain attached to the cation, was studied in the temperature range between 173 K and 393 K. The glass formation of the ionic liquids is influenced by the length of the alkyl spacer separating the nitrile function from the pyrrolidinium ring. The electrical conductivity and the viscosity do not show a monotonic dependence on the alkyl spacer length, but rather an odd-even effect. An explanation for this behavior is given, including the potential energy landscape picture for the glass transition.

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n the context of psychosocial oncology research, disseminating study findings to a range of knowledge “end-users” can advance the well-being of diverse patient subgroups and their families. This article details how findings drawn from a study of prostate cancer support groups were repackaged in a knowledge translation website—www.prostatecancerhelpyourself.ubc.ca—using Web 2.0 features. Detailed are five lessons learned from developing the website: the importance of pitching a winning but feasible idea, keeping a focus on interactivity and minimizing text, negotiating with the supplier, building in formal pretests or a pilot test with end-users, and completing formative evaluations based on data collected through Google™ and YouTube™ Analytics. The details are shared to guide the e-knowledge translation efforts of other psychosocial oncology researchers and clinicians.