Multiatom and transit-time effects on photon-correlation measurements in resonance fluorescence

An expression is derived for the expected number of photon pairs separated by a time interval τ that are detected in photoelectric correlation measurements of an atomic beam, when due account is taken of the fluctuations of the number of radiating atoms and of the effect of their finite transit time through the field of view. The theoretical expression is checked against some recent measurements and good agreement is obtained

Innovativity: a comparison across seven European countries

Nous proposons, dans cette étude, un cadre d'analyse, ou « comptabilité de l'innovation », semblable à celui très généralement utilisé pour la « comptabilité de la croissance », ainsi qu'une mesure de la « productivité des facteurs d'innovation » ou « innovativité » comparable à celle de la productivité totale des facteurs. Nous appliquons ce cadre d'analyse à la comparaison de l'innovation pour sept pays européens - l'Allemagne, la Belgique, le Danemark, l'Irlande, l'Italie, la Norvège et les Pays-Bas -, à partir des données d'entreprises « micro agrégées » de la première enquête communautaire sur l'innovation (CIS1) portant sur l'année 1992. Sur la base d'un modèle Tobit généralisé et en mesurant l'innovation par la part du chiffre d'affaires des entreprises en produits innovants (nouveaux ou améliorés sur les trois années 1990-1992), nous estimons la propension à innover et l'intensité de l'innovation (conditionnellement ou non au fait d'innover) pour les industries manufacturières de haute et basse technologie des sept pays. Bien que disposant de variables explicatives peu nombreuses, nous rendons compte ainsi de différences déjà très significatives d'intensité d'innovation entre pays. Les différences d'innovativité entre pays restent néanmoins très fortes.This paper proposes a framework to account for innovation similar to the usual accounting framework in production analysis and a measure of "innovativity" comparable to that of total factor productivity. This innovation accounting framework is illustrated using micro-aggregated firm data from the first Community Innovation Surveys (CIS1) for seven European countries: Belgium, Denmark, Ireland, Germany, the Netherlands, Norway and Italy for the year 1992. Based on the estimation of a generalized Tobit model and measuring innovation as the share of total sales due to improved or new products, it compares the propensity to innovate, and the innovation intensity conditional and unconditional on being innovative, across the seven countries and low- and high-tech manufacturing sectors. Even with relatively few explanatory variables our innovation framework already accounts for sizeable differences in country innovation intensity. It also shows that differences in innovativity across countries can be nonetheless very large

Educational Research in Educational Practice: Predictors of Use

This study investigates the predictors of school practitioners’ (N = 2,425) use of educational research. The suggested model explained significantly but modestly the infrequent use of educational research by practitioners. Of the four factors in the study, “opinions about research” had the most explanatory power. The results are discussed in connection with existing knowledge about school practitioners’ use of educational research and implications for further research and practice

Testing predictions of inclusive fitness theory in inbreeding relatives with biparental care

Data accessibility Data are deposited in Dryad https:doi.org/10.5061/dryad.1zcrdfnf. R code supporting this article has been uploaded as part of the electronic supplementary material. Acknowledgements We thank the Tsawout and Tseycum First Nation bands for allowing access to Mandarte, numerous field assistants, graduate students and postdoctoral fellows who contributed to long-term data collection, and Brad Duthie for insightful discussions regarding underlying concepts. National Sciences and Engineering Research Council (P.A., E.A.G); Izaak Walton Killam Memorial Fund for Advanced Studies (E.A.G, J.M.R.), UK Natural Environment Research Council (R.J.S.) and the European Research Council (J.M.R.) provided funding.Peer reviewedPostprin

Genetic dysbiosis: the role of microbial insults in chronic inflammatory diseases

This review was undertaken at UCL, which received a proportion of funding from the Department of Health’s National Institute of Health Research (NIHR) Biomedical Research Centres funding scheme

Hydrodynamic stress and phenotypic plasticity of the zebrafish regenerating fin

Understanding how extrinsic factors modulate genetically encoded information to produce a specific phenotype is of prime scientific interest. In particular, the feedback mechanism between abiotic forces and locomotory organs during morphogenesis to achieve efficient movement is a highly relevant example of such modulation. The study of this developmental process can provide unique insights on the transduction of cues at the interface between physics and biology. Here, we take advantage of the natural ability of adult zebrafish to regenerate their amputated fins to assess its morphogenic plasticity upon external modulations. Using a variety of surgical and chemical treatments, we could induce phenotypic responses to the structure of the fin. Through the ablation of specific rays in regenerating caudal fins, we generated artificially narrowed appendages in which the fin cleft depth and the positioning of rays bifurcations were perturbed compared with normal regenerates. To dissect the role of mechanotransduction in this process, we investigated the patterns of hydrodynamic forces acting on the surface of a zebrafish fin during regeneration by using particle tracking velocimetry on a range of biomimetic hydrofoils. This experimental approach enabled us to quantitatively compare hydrodynamic stress distributions over flapping fins of varying sizes and shapes. As a result, viscous shear stress acting on the distal margin of regenerating fins and the resulting internal tension are proposed as suitable signals for guiding the regulation of ray growth dynamics and branching pattern. Our findings suggest that mechanical forces are involved in the fine-tuning of the locomotory organ during fin morphogenesis