Search for Hadronic Charmless Decays of B Mesons

Using a data sample of about 4 millions hadronic Z decays recorded by the ALEPH experiment at LEP during the years 1991 to 1995, a search is made for exclusive decays of B mesons into charmless hadronic final states. Various decay modes are analysed, including modes with charged and neutral pions as well as modes with baryons or light resonances. Limits on the branching ratios of these decay modes are given

Probabilistic reconstruction of genealogies for polyploid plant species

A probabilistic reconstruction of genealogies in a polyploid population (from 2x to 4x) is investigated, by considering genetic data analyzed as the probability of allele presence in a given genotype. Based on the likelihood of all possible crossbreeding patterns, our model enables to infer and to quantify the whole potential genealogies in the population. We explain in particular how to deal with the uncertain allelic multiplicity that may occur with polyploids. Then we build an ad hoc penalized likelihood to compare genealogies and to decide whether a particular individual brings a sufficient information to be included in the taken genealogy. This decision criterion enables us in a next part to suggest a greedy algorithm in order to explore missing links and to rebuild some connections in the genealogies, retrospectively. As a by-product, we also give a way to infer the individuals that may have been favored by breeders over the years. In the last part we highlight the results given by our model and our algorithm, firstly on a simulated population and then on a real population of rose bushes. Most of the methodology relies on the maximum likelihood principle and on the graph theory

Block to granular-like transition in dense bubble flows

We have experimentally investigated 2-dimensional dense bubble flows underneath inclined planes. Velocity profiles and velocity fluctuations have been measured. A broad second-order phase transition between two dynamical regimes is observed as a function of the tilt angle $\theta$. For low $\theta$ values, a block motion is observed. For high $\theta$ values, the velocity profile becomes curved and a shear velocity gradient appears in the flow.Comment: Europhys. Lett. (2003) in pres

Molecular oxygen generation from the reaction of water cations with oxygen atoms

© 2019 Author(s). The oxywater cation (H2OO+), previously shown to form barrierlessly in the gas phase from water cations and atomic oxygen, is proposed here potentially to possess a 2A″ ← 4A″ excitation leading to the H2⋯O2+ complex. This complex could then easily decompose into molecular hydrogen and the molecular oxygen cation. The present quantum chemical study shows that the necessary electronic transition takes place in the range of 1.92 eV (645 nm), in the orange-red range of the visible and solar spectrum, and dissociation of the complex only requires 5.8 kcal/mol (0.25 eV). Such a process for the abiotic, gas phase formation of O2 would only need to be photocatalyzed by visible wavelength photons. Hence, such a process could produce O2 at the mesosphere/stratosphere boundary as climate change is driving more water into the upper atmosphere, in the comet 67P/Churyumov-Gerasimenko where surprisingly high levels of O2 have been observed, or at gas-surface (ice) interfaces

Atrésie choanale : A propos de 29 cas

Introduction : L’atrésie choanale est une malformation congénitale rare, dont la fréquence est estimée à 1 cas pour 5000 à 8000 naissances. plusieurs hypothèses embryologiques ont été proposées pour expliquer son origine. Le diagnostic de cette malformation est avant tout clinique.Objectifs : analyser les caractéristiques épidémio-cliniques et  paracliniques des atrésies choanales et discuter les modalités thérapeutiques de cette malformation.Matériel et méthodes : il s'agit d'une étude rétrospective à propos de 29 cas d'atrésie choanale suivis au service d'Otorhinolaryngologie de l'hôpital la Rabta sur une période de 20 ans (1990-2009).Résultats : L'âge moyen de découverte était de 10,6 ans (1 jour - 35 ans). Une prédominance féminine a été notée. L'atrésie était bilatérale dans 8 cas et unilatérale dans 21 cas. Un scanner du massif facial a été réalisé dans 23 cas. L'atrésie était osseuse dans 30,4 % des cas, membraneuse dans 13 % et mixte dans 56,6 %. Concernant le  traitement, on a eu recours à la divulsion dans un cas, la voie  transpalatine dans 15 cas (dont 2 aprés echec divulsion première) etla voie endonasale dans 13 cas.  Le taux de succès obtenu par la voie endoscopique endonasale est évalué à 72,72% et par la voie transpalatine à 71,42%. Le taux de succès passe à 100% après reprise chirurgicale.Conclusion : L’atrésie choanale est une pathologie qui doit être dépistée à la période néonatale. L’endoscopie nasale et le scanner ont complètement révolutionné les approches diagnostiques et thérapeutiques de cette pathologie. La chirurgie endonasale sous guidage endoscopique est actuellement la technique de choix.Mots clés : atrésie ; choane ; chirurgie endoscopiqu

Averages of b-hadron Properties at the End of 2005

This article reports world averages for measurements on b-hadron properties obtained by the Heavy Flavor Averaging Group (HFAG) using the available results as of at the end of 2005. In the averaging, the input parameters used in the various analyses are adjusted (rescaled) to common values, and all known correlations are taken into account. The averages include lifetimes, neutral meson mixing parameters, parameters of semileptonic decays, branching fractions of B meson decays to final states with open charm, charmonium and no charm, and measurements related to CP asymmetries

The problem-solving method:Efficacy for learning and motivation in the field of physical education

Background: In pursuit of quality teaching and learning, teachers seek the best method to provide their students with a positive educational atmosphere and the most appropriate learning conditions. Objectives: The purpose of this study is to compare the effects of the problem-solving method vs. the traditional method on motivation and learning during physical education courses. Methods: Fifty-three students (M age 15 ± 0.1 years), in their 1st year of the Tunisian secondary education system, voluntarily participated in this study, and randomly assigned to a control or experimental group. Participants in the control group were taught using the traditional methods, whereas participants in the experimental group were taught using the problem-solving method. Both groups took part in a 10-hour experiment over 5 weeks. To measure students' situational motivation, a questionnaire was used to evaluate intrinsic motivation, identified regulation, external regulation, and amotivation during the first (T0) and the last sessions (T2). Additionally, the degree of students' learning was determined via video analyses, recorded at T0, the fifth (T1), and T2. Results: Motivational dimensions, including identified regulation and intrinsic motivation, were significantly greater (all p < 0.001) in the experimental vs. the control group. The students' motor engagement in learning situations, during which the learner, despite a degree of difficulty performs the motor activity with sufficient success, increased only in the experimental group (p < 0.001). The waiting time in the experimental group decreased significantly at T1 and T2 vs. T0 (all p < 0.001), with lower values recorded in the experimental vs. the control group at the three-time points (all p < 0.001). Conclusions: The problem-solving method is an efficient strategy for motor skills and performance enhancement, as well as motivation development during physical education courses.BackgroundIn pursuit of quality teaching and learning, teachers seek the best method to provide their students with a positive educational atmosphere and the most appropriate learning conditions. ObjectivesThe purpose of this study is to compare the effects of the problem-solving method vs. the traditional method on motivation and learning during physical education courses. MethodsFifty-three students (M-age 15 +/- 0.1 years), in their 1st year of the Tunisian secondary education system, voluntarily participated in this study, and randomly assigned to a control or experimental group. Participants in the control group were taught using the traditional methods, whereas participants in the experimental group were taught using the problem-solving method. Both groups took part in a 10-hour experiment over 5 weeks. To measure students' situational motivation, a questionnaire was used to evaluate intrinsic motivation, identified regulation, external regulation, and amotivation during the first (T0) and the last sessions (T2). Additionally, the degree of students' learning was determined via video analyses, recorded at T0, the fifth (T1), and T2. ResultsMotivational dimensions, including identified regulation and intrinsic motivation, were significantly greater (all p < 0.001) in the experimental vs. the control group. The students' motor engagement in learning situations, during which the learner, despite a degree of difficulty performs the motor activity with sufficient success, increased only in the experimental group (p < 0.001). The waiting time in the experimental group decreased significantly at T1 and T2 vs. T0 (all p < 0.001), with lower values recorded in the experimental vs. the control group at the three-time points (all p < 0.001). ConclusionsThe problem-solving method is an efficient strategy for motor skills and performance enhancement, as well as motivation development during physical education courses