194 research outputs found

    Rotationally resolved threshold photoelectron spectra of OH and OD

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    The results of combined experimental and theoretical studies of the rotationally resolved photoelectron spectra of OH and OD following single‐photon ionization are presented. The measured zero‐kinetic‐energy (ZEKE) spectra were obtained using pulsed field ionization in conjunction with a vacuum ultraviolet laser source. The OH^+ and OD^+ (X ^3Σ^−, v^+=0) rotational distributions were studied over the range 95.0–95.4 nm. Agreement between the observed and calculated spectra is very encouraging. Improved values for the ionization potentials of OH and OD (104 989 and 105 085 ± 2 cm^(−1), respectively) are reported and the unusual dynamics favoring ΔN<0 transitions are discussed

    A comparative study of the variables used to measure syntactic complexity and accuracy in task-based research

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    The constructs of complexity, accuracy and fluency (CAF) have been used extensively to investigate learner performance on second language tasks. However, a serious concern is that the variables used to measure these constructs are sometimes used conventionally without any empirical justification. It is crucial for researchers to understand how results might be different depending on which measurements are used, and accordingly, choose the most appropriate variables for their research aims. The first strand of this article examines the variables conventionally used to measure syntactic complexity in order to identify which may be the best indicators of different proficiency levels, following suggestions by Norris and Ortega. The second strand compares the three variables used to measure accuracy in order to identify which one is most valid. The data analysed were spoken performances by 64 Japanese EFL students on two picture-based narrative tasks, which were rated at Common European Framework of Reference for Languages (CEFR) A2 to B2 according to Rasch-adjusted ratings by seven human judges. The tasks performed were very similar, but had different degrees of what Loschky and Bley-Vroman term ‘task-essentialness’ for subordinate clauses. It was found that the variables used to measure syntactic complexity yielded results that were not consistent with suggestions by Norris and Ortega. The variable found to be the most valid for measuring accuracy was errors per 100 words. Analysis of transcripts revealed that results were strongly influenced by the differing degrees of task-essentialness for subordination between the two tasks, as well as the spread of errors across different units of analysis. This implies that the characteristics of test tasks need to be carefully scrutinised, followed by careful piloting, in order to ensure greater validity and reliability in task-based research

    Ion rotational distributions for near-threshold photoionization of H_2O

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    Ion rotational distributions for single‐photon VUV photoionization of the 1b_1 orbital of the X̃ ^1A_1 ground state of the jet‐cooled water are reported. These spectra reveal significant type a transitions which are seen to arise from odd angular momentum components of the photoelectron matrix element. The resulting photoionization dynamics are quite nonatomic‐like

    Measuring Syntactic Complexity in Spoken and Written Learner Language: Comparing the Incomparable?

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    Spoken and written language are two modes of language. When learners aim at higher skill levels, the expected outcome of successful second language learning is usually to become a fluent speaker and writer who can produce accurate and complex language in the target language. There is an axiomatic difference between speech and writing, but together they form the essential parts of learners’ L2 skills. The two modes have their own characteristics, and there are differences between native and nonnative language use. For instance, hesitations and pauses are not visible in the end result of the writing process, but they are characteristic of nonnative spoken language use. The present study is based on the analysis of L2 English spoken and written productions of 18 L1 Finnish learners with focus on syntactic complexity. As earlier spoken language segmentation units mostly come from fluency studies, we conducted an experiment with a new unit, the U-unit, and examined how using this unit as the basis of spoken language segmentation affects the results. According to the analysis, written language was more complex than spoken language. However, the difference in the level of complexity was greatest when the traditional units, T-units and AS-units, were used in segmenting the data. Using the U-unit revealed that spoken language may, in fact, be closer to written language in its syntactic complexity than earlier studies had suggested. Therefore, further research is needed to discover whether the differences in spoken and written learner language are primarily due to the nature of these modes or, rather, to the units and measures used in the analysis

    First-time-in-human study and prediction of early bactericidal activity for GSK3036656, a potent leucyl-tRNA synthetase inhibitor for tuberculosis treatment

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    This first-time-in-human (FTIH) study evaluated the safety, tolerability, pharmacokinetics, and food effect of single and repeat oral doses of GSK3036656, a leucyl-tRNA synthetase inhibitor. In part A, GSK3036656 single doses of 5 mg (fed and fasted), 15 mg, and 25 mg and placebo were administered. In part B, repeat doses of 5 and 15 mg and placebo were administered for 14 days once daily. GSK3036656 showed dose-proportional increase following single-dose administration and after dosing for 14 days. The maximum concentration of drug in serum (Cmax) and area under the concentration-time curve from 0 h to the end of the dosing period (AUC0–τ) showed accumulation with repeated administration of approximately 2- to 3-fold. Pharmacokinetic parameters were not altered in the presence of food. Unchanged GSK3036656 was the only drug-related component detected in plasma and accounted for approximately 90% of drug-related material in urine. Based on total drug-related material detected in urine, the minimum absorbed doses after single (25 mg) and repeat (15 mg) dosing were 50 and 78%, respectively. Unchanged GSK3036656 represented at least 44% and 71% of the 25- and 15-mg doses, respectively. Clinical trial simulations were performed to guide dose escalation during the FTIH study and to predict the GSK3036656 dose range that produces the highest possible early bactericidal activity (EBA0–14) in the prospective phase II trial, with consideration of the predefined exposure limit. GSK3036656 was well tolerated after single and multiple doses, with no reports of serious adverse events. (This study has been registered at ClinicalTrials.gov under identifier NCT03075410.

    Individual differences in early language learning: a study of English learners of French

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    The present longitudinal study examines the interaction of learner variables (gender, motivation, self-efficacy and first language literacy) and their influence on second language learning outcomes. The study follows English learners of French from Year 5 in primary school (aged 9-10) to the first year in secondary school (Year 7 aged 11-12). Language outcomes were measured by two oral production tasks; a sentence repetition task and a photo description task both of which were administered at three time points. Longitudinal data on learner attitudes and motivation were collected via questionnaires. Teacher assessment data for general first language literacy attainment were also provided. The results show a great deal of variation in learner attitudes and outcomes and that there is a complex relationship between first language literacy, self-efficacy, gender and attainment. For example, in general, girls held more positive attitudes to boys and were more successful. However, the inclusion of first language ability, which explained 30-40% of variation, shows that gender differences in attitudes and outcomes are likely mediated by first language literacy and prior learning experience

    Cluster Analysis and Comparison of Various Chloroplast Transcriptomes and Genes in Arabidopsis thaliana

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    Chloroplast RNA metabolism is integrated into wider gene regulatory networks. To explore how, we performed a chloroplast genome-wide expression analysis on numerous nuclear Arabidopsis mutants affected in diverse chloroplast functions and wild-type plants subjected to various stresses and conditions. On the basis of clustering analysis, plastid genes could be divided into two oppositely regulated clusters, largely congruent with known targets of nucleus- and plastid-encoded RNA polymerases, respectively. Further eight sub-clusters contained co-transcribed and functionally tightly associated genes. The chloroplast transcriptomes could also be classified into two major groups comprising mutants preferentially affected in general plastid gene expression and other chloroplast functions, respectively. Deviations from characteristic expression profiles of transcriptomes served to identify novel mutants impaired in accumulation and/or processing of specific plastid RNAs. Expression profiles were useful to distinguish albino mutants affected in plastid gene expression from those with defects in other plastid functions. Remarkably, biotic and abiotic stressors did not define transcriptionally determined clusters indicating that post-transcriptional regulation of plastid gene expression becomes more important under changing environmental conditions. Overall, the identification of sets of co-regulated genes provides insights into the integration of plastid gene expression into common pathways that ensures a coordinated response

    Non-Thermal Plasma System Development for CIDI Exhaust Aftertreatment

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    There is a need for an efficient, durable technology to reduce NOx emissions from oxidative exhaust streams such as those produced by compression-ignition, direct injection (CIDI) diesel or lean-burn gasoline engines. A partnership formed between the DOE Office of Advanced Automotive Technology, Pacific Northwest National Laboratory, Oak Ridge National Laboratory and the USCAR Low Emission Technologies Research and Development Partnership is evaluating the effectiveness of a non-thermal plasma in conjunction with catalytic materials to mediate NOx and particulate emissions from diesel fueled light duty (CIDI) engines. Preliminary studies showed that plasma-catalyst systems could reduce up to 70% of NOx emissions at an equivalent cost of 3.5% of the input fuel in simulated diesel exhaust. These studies also showed that the type and concentration of hydrocarbon play a key role in both the plasma gas phase chemistry and the catalyst surface chemistry. More recently, plasma/catalyst systems have been evaluated for NOx reduction and particulate removal on a CIDI engine. Performance results for select plasma-catalyst systems for both simulated and actual CIDI exhaust will be presented. The effect of NOx and hydrocarbon concentration on plasma-catalyst performance will also be shown. SAE Paper SAE-2000-01-1601 {copyright} 2000 SAE International. This paper is published on this website with permission from SAE International. As a user of this website, you are permitted to view this paper on-line, download this pdf file and print one copy of this paper at no cost for your use only. The downloaded pdf file and printout of this SAE paper may not be copied, distributed or forwarded to others or for the use of others
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