30,865 research outputs found

    Loop groups and diffeomorphism groups of the circle as colimits

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    We show that loop groups and the universal cover of Diff+(S1)\mathrm{Diff}_+(S^1) can be expressed as colimits of groups of loops/diffeomorphisms supported in subintervals of S1S^1. Analogous results hold for based loop groups and for the based diffeomorphism group of S1S^1. These results continue to hold for the corresponding centrally extended groups. We use the above results to construct a comparison functor from the representations of a loop group conformal net to the representations of the corresponding affine Lie algebra. We also establish an equivalence of categories between solitonic representations of the loop group conformal net, and locally normal representations of the based loop group.Comment: updated to published versio

    What Chern-Simons theory assigns to a point

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    In this note, we answer the questions "What does Chern-Simons theory assign to a point?" and "What kind of mathematical object does Chern-Simons theory assign to a point?". Our answer to the first question is representations of the based loop group. More precisely, we identify a certain class of projective unitary representations of the based loop group ΩG\Omega G that we locally normal representations. We define the fusion product of such representations and we prove that, modulo certain conjectures, the Drinfel'd centre of that representation category of ΩG\Omega G is equivalent to the category of positive energy representations of the free loop group LGLG. The above mentioned conjectures are known to hold when the gauge group is abelian or of type A1A_1. Our answer to the second question is bicommutant categories. The latter are higher categorical analogs of von Neumann algebras: they are tensor categories that are equivalent to their bicommutant inside Bim(R)\mathrm{Bim}(R), the category of bimodules over a hyperfinite III1\mathit{III}_1 factor. We prove that, modulo certain conjectures, the category of locally normal representations of the based loop group is a bicommutant category. The relevant conjectures are known to hold when the gauge group is abelian or of type AnA_n. Our work builds on the formalism of coordinate free conformal nets, developed jointly with A. Bartels and C. Douglas.Comment: Minor changes. Added a summary diagram at the end. Replaced the terminology "positive energy representations of the based loop group" by "locally normal representations of the based loop group

    Students' Perceptions of their Rights in Portugal

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    The present study analyses young Portuguese students’perceptions of their rights at school and at home. The sample consisted of 294 male and female students, in Year 7 to Year 9, from several regions in the country. The assessment instrument used was the ‘Children’s Rights Scale’ (Hart, 1993; Hart et al., 1996) and results were related to a number of other questions regarding the following independent variables: (1) school variables (school year, school achievement, teacher’s support, violence at school); (2) family variables (parental authority, family cohesion, parents’ education); (3) personal variables (age, gender, professional interests). Significant relations were found between the students’ perceptions of their rights and these independent variables. In general, Portuguese students declare that their rights exist and are very important. Students who have a greater degree of personal limitations, or who live in worse school or family contexts, are the ones who indicate less importance and perceive less existence of rights at school and at home. The study gives directions to efforts to strengthen projects for the promotion of students’ rights by including training programs for teachers and parents, in a close net connection among school, family and significant social agents.This study was financed by JNICT/FCT and by the PRAXIS XXI Program for the period from 1997 to 2002 and developed at the Center for Research in Education of the Faculty of Sciences of the University of Lisbon (CIEFCUL)R. Ernesto Vasconcelos, Edif. C1–2º, 1749–016 Lisbon, Portugal

    Loop quantum cosmology and the Wheeler-De Witt equation

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    We present some results concerning the large volume limit of loop quantum cosmology in the flat homogeneous and isotropic case. We derive the Wheeler-De Witt equation in this limit. Looking for the action from which this equation can also be obtained, we then address the problem of the modifications to be brought to the Friedman's equation of motion and to the equation of motion of the scalar field, in the classical limit.Comment: 17 pages; 5 figure

    Promotion of rights and behavioural adequacy of students in school: Effects of a Transactional Analysis Programme

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    This study aimed to investigate the effects of teachers’ use of an Transactional Analysis Intervention Programme, on rights and behavioural adequacy of students in school. Specific formation was given to a group of teachers interested in the study, in which 8th grade students participated. The following evaluation instruments were used: the Children’s Rights Scale (Hart et al., 1996), and the School Disruption Professed by Students Scale(Veiga, 1996). These scales were applied before and after the intervention. The intervention lasted around 18 school weeks. The Transactional Analysis Intervention Programme was applied to the experimental group, and the control group continued to be the object of the type of teacher-student relationship practiced so far. The analysis of the results revealed statistically significant differences in the experimental group between the pretest and posttest situation, while this did not occur in the control group. The differences between the control group and the experimental group went from non-significant, in the pretest situation, to statistically significant and favorable for the experimental group, in the posttest situation. The study carried out stresses benefits for the students of the experimental group, who increase their rights and mprove their behavioural adequacy in school
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