The PHaVE List: a pedagogical list of phrasal verbs and their most frequent meaning senses

As researchers and practitioners are becoming more aware of the importance of multi-word items in English, there is little doubt that phrasal verbs deserve teaching attention in the classroom. However, there are thousands of phrasal verbs in English, and so the question for practitioners is which phrasal verbs to focus attention upon. Phrasal verb dictionaries typically try to be comprehensive, and this results in a very large number of phrasal verbs being listed, which does not help practitioners in selecting the most important ones to teach or test. There are phrasal verb lists available (Gardner and Davies, 2007; Liu, 2011), but these have a serious pedagogical shortcoming in that they do not account for polysemy. Research indicates that phrasal verbs are highly polysemous, having on average 5.6 meaning senses, although many of these are infrequent and peripheral. Thus practitioners also need guidance about which meaning senses are the most useful to address in instruction or tests. In response to this need, the PHrasal VErb Pedagogical List (PHaVE List) was developed. It lists the 150 most frequent phrasal verbs, and provides information on their key meaning senses, which cover 75%+ of the occurrences in the Corpus of Contemporary American English. The PHaVE List gives the percentage of occurrence for each of these key meaning senses, along with definitions and example sentences written to be accessible for second language learners, in the style of the General Service List (West, 1953). A users’ manual is also provided, indicating how to use the list appropriately

Directional trends in species composition over time can lead to a widespread overemphasis of year‐to‐year asynchrony

Questions: Compensatory dynamics are described as one of the main mechanisms that increase community stability, e.g., where decreases of some species on a year‐to‐year basis are offset by an increase in others. Deviations from perfect synchrony between species (asynchrony) have therefore been advocated as an important mechanism underlying biodiversity effects on stability. However, it is unclear to what extent existing measures of synchrony actually capture the signal of year‐to‐year species fluctuations in the presence of long‐term directional trends in both species abundance and composition (species directional trends hereafter). Such directional trends may lead to a misinterpretation of indices commonly used to reflect year‐to‐year synchrony. Methods: An approach based on three‐term local quadrat variance (T3) which assesses population variability in a three‐year moving window, was used to overcome species directional trend effects. This “detrending” approach was applied to common indices of synchrony across a worldwide collection of 77 temporal plant community datasets comprising almost 7,800 individual plots sampled for at least six years. Plots included were either maintained under constant “control” conditions over time or were subjected to different management or disturbance treatments. Results: Accounting for directional trends increased the detection of year‐to‐year synchronous patterns in all synchrony indices considered. Specifically, synchrony values increased significantly in ~40% of the datasets with the T3 detrending approach while in ~10% synchrony decreased. For the 38 studies with both control and manipulated conditions, the increase in synchrony values was stronger for longer time series, particularly following experimental manipulation. Conclusions: Species’ long‐term directional trends can affect synchrony and stability measures potentially masking the ecological mechanism causing year‐to‐year fluctuations. As such, previous studies on community stability might have overemphasised the role of compensatory dynamics in real‐world ecosystems, and particularly in manipulative conditions, when not considering the possible overriding effects of long‐term directional trends

LOTVS: a global collection of permanent vegetation plots

Analysing temporal patterns in plant communities is extremely important to quantify the extent and the consequences of ecological changes, especially considering the current biodiversity crisis. Long-term data collected through the regular sampling of permanent plots represent the most accurate resource to study ecological succession, analyse the stability of a community over time and understand the mechanisms driving vegetation change. We hereby present the LOng-Term Vegetation Sampling (LOTVS) initiative, a global collection of vegetation time-series derived from the regular monitoring of plant species in permanent plots. With 79 data sets from five continents and 7,789 vegetation time-series monitored for at least 6 years and mostly on an annual basis, LOTVS possibly represents the largest collection of temporally fine-grained vegetation time-series derived from permanent plots and made accessible to the research community. As such, it has an outstanding potential to support innovative research in the fields of vegetation science, plant ecology and temporal ecology

Etude de la dynamique Brownienne au voisinage d'une paroi par diffusion de lumiere en onde evanescente

SIGLEINIST T 76778 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Brownian dynamics close to a wall, measured by quasi-elastic light scattering from an evanescent wave

International audienceThe Brownian dynamics of a colloidal suspension is measured in the immediate vicinity of a rigid surface by the evanescent quasi-elastic light-scattering technique. A net decrease of the measured diffusion coefficient is observed, due to the hydrodynamic slowing down of the particles very close to the wall. This effect is all the more important when the particles are allowed to get close to the wall, i.e., when the range of the static wall/particle repulsive interaction decreases. It thus provides a mean for testing the particle/wall static interactions via a dynamic light-scattering measurement. The data are analyzed by Brownian dynamic simulations which are proven to be quite valuable to interpret light-scattering data from “hindered” scatterers, such as particles confined in the neighborhood of a wall, or trapped in a porous media or a gel

Quasi-elastic light scattering from an evanescent wave to probe particle/wall interactions.

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Picking up polysemous phrasal verbs: How many do learners know and what facilitates this knowledge?

© 2016 Elsevier Ltd. This study investigates L2 learners' knowledge of highly frequent polysemous phrasal verbs in English, and the effect of a number of factors on this knowledge. 128 students on BA English/TEFL courses were recruited to take a productive test in the form of a gap-fill task. The results show that only 40% of phrasal verb meaning senses were known on average, with the chances of knowing all the different meaning senses of each phrasal verb tested being quite low at only around 20%. The factors of semantic opacity, previous L2 instruction, immersion in L2 environment, and year of BA study did not have any effect on knowledge. Conversely, corpus frequency was found to predict knowledge, along with time spent reading per week, and time spent social networking per week. No relationship was found between phrasal verb knowledge and the hours spent listening to music and watching films in English. The study confirms that phrasal verbs are a problematic feature of English vocabulary for many learners, and consequently deserve more attention - either via instructed contexts or outside the classroom in L2 language engagement

Correlated motions and propagation of the effect of a local conformational change in the transmembrane helix of the c-erb B2 encoded protein and its V659E mutant, studied by molecular dynamics simulations.

International audienceA detailed study of the dynamical behavior of the 29-residue peptide including the transmembrane domain of p185c-erbB2 oncogene-encoded protein and of its V659E mutant is presented. In a first part of this work we analyse equal time correlation coefficients between the backbone dihedral angle fluctuations. Concerted motions are observed in the wild type transmembrane alpha-helix but not in the corresponding V659E intramembrane domain. The difference observed in the correlation pattern is attributed to the single amino acid replacement. In a second part, we investigate the propagation of the effect of a local conformational change along the transmembrane segment, one of the dominant hypotheses for signal transduction mechanisms of transmembrane receptors. The analysis of angular time correlation functions together with that of the response of the different residues to a local disturbance applied at the N-terminal side evidences a propagation phenomenon for the wild type peptide. This effect is much less clear for the mutated peptide. Furthermore we show that the first one is much more flexible than the second one

Dimer models for ErbB-2/neu transmembrane domains from molecular dynamics simulations

International audienceInterest in the transmembrane receptors tyrosine kinase of the erbB family is high due to the involvement of some of the members in human cancers. The original oncogenic alleles of neu discovered in rat neuroectodermal tumors lead to single Val664Glu substitution within the predicted transmembrane domain. Identical substitution at the homologous position 659 constitutively activates the oncogenic potential of the human ErbB-2 receptor by enhanced receptor dimer formation. The precise molecular details of receptor dimerization are still unknown and to acquire more knowledge of the mechanisms involved, molecular dynamics simulations are undertaken to study transmembrane dimer association. Transmembrane helices are predicted to associate in left-handed coiled-coil structures stabilized by Glu-Glu interhelix hydrogen bonds in the mutated form. The internal dynamics reveals π helix deformations which modify the helix-helix interface. Predicted models agree with those suggested from polarized IR and magic-angle spinning NMR spectroscopy