Coupled molecule-radiation field effects in an ammonia beam maser

Details are given of a number of phenomena which have been observed in an advanced ammonia beam maser. These include cooperative effects arising during the build-up of oscillations, regenerative nutation, pulling and quenching of oscillations, induced spiking, biharmonic operation in a magnetic field, hysteresis effects and polarization transients. The relevance of each of these to other areas of quantum electronics is discussed

Activity-based scenarios for and approaches to ubiquitous e-Learning

This paper presents scenarios for ubiquitous e-Learning in heterogeneous networks. It concludes by arguing for the development of a learning-focused analogue, activity-based e-Learning extensions (ABLE), of activity-based computing (ABC). The goal would be to offer the learning-support/performance-support equivalent of ABC’s support for human activities in a ubiquitous computing environment, relevant to areas that are hard to model today: informal on-the-job learning; peer-to-peer support and informal sharing of content in ad hoc work groups; formal and informal ways to capture and share knowledge-focused insights and processes; content and systems to aid reflection. Just as ABC supplements traditional computing approaches (in ABC, data- and application-oriented) to suit ‘multiple, parallel and mobile work activities’ (Bardram et al. in Support for ABC in a personal computing operating system. CHI 2006 proceedings. Montréal, Québec, Canada, 22–27 April 2006, pp 211–220), so ABLE could supplement traditional e-learning approaches (often largely content-focused, sometimes little more than page-turning) to suit those same work activities, and make e-Learning potentially more resilient to interruptions, more fun and more memorable

Decreased telomere length in a subgroup of young individuals with bipolar disorders: replication in the FACE-BD cohort and association with the shelterin component POT1

International audienceBipolar disorder (BD) has been associated with premature cellular aging with shortened telomere length (TL) as compared to the general population. We recently identified a subgroup of young individuals with prematurely shortened TL. The aims of the present study were to replicate this observation in a larger sample and analyze the expression levels of genes associated with age or TL in a subsample of these individuals. TL was measured on peripheral blood DNA using quantitative polymerase chain reaction in a sample of 542 individuals with BD and clustering analyses were performed. Gene expression level of 29 genes, associated with aging or with telomere maintenance, was analyzed in RNA samples from a subsample of 129 individuals. Clustering analyses identified a group of young individuals (mean age 29.64 years), with shorter TL. None of the tested clinical variables were significantly associated with this subgroup. Gene expression level analyses showed significant downregulation of MYC, POT1, and CD27 in the prematurely aged young individuals compared to the young individuals with longer TL. After adjustment only POT1 remained significantly differentially expressed between the two groups of young individuals. This study confirms the existence of a subgroup of young individuals with BD with shortened TL. The observed decrease of POT1 expression level suggests a newly described cellular mechanism in individuals with BD, that may contribute to telomere shortening