11,425 research outputs found

    The flux of carbonyl sulfide and carbon disulfide between the atmosphere and a spruce forest

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    Turbulent fluxes of carbonyl sulfide (COS) and carbon disulfide (CS2) were measured over a spruce forest in Central Germany using the relaxed eddy accumulation (REA) technique. A REA sampler was developed and validated using simultaneous measurements of CO2 fluxes by REA and by eddy correlation. REA measurements were conducted during six campaigns covering spring, summer, and fall between 1997 and 1999. Both uptake and emission of COS and CS2 by the forest were observed, with deposition occurring mainly during the sunlit period and emission mainly during the dark period. On the average, however, the forest acts as a sink for both gases. The average fluxes for COS and CS2 are -93 ± 11.7 pmol m-2 s-1 and -18 ± 7.6 pmol m-2 s-1, respectively. The fluxes of both gases appear to be correlated to photosynthetically active radiation and to the CO2 and \chem{H_2O} fluxes, supporting the idea that the air-vegetation exchange of both gases is controlled by stomata. An uptake ratio COS/CO2 of 10 ± 1.7 pmol m mol-1 has been derived from the regression line for the correlation between the COS and CO2 fluxes. This uptake ratio, if representative for the global terrestrial net primary production, would correspond to a sink of 2.3 ± 0.5 Tg COS yr-1

    ‘Only true friends could be cruelly honest’: Cognitive scaffolding and social-affective support in teacher feedback literacy

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    Feedback is an important but challenging aspect of higher education pedagogy. In addition to providing quality feedback, teachers are expected to develop students’ skills and awareness for effective feedback processes. This case study addresses both processes and products of a Chinese university English teacher’s feedback enabling practice by involving students in peer feedback on oral presentations. Data from classroom observations and interviews reveal various strategies of cognitive scaffolding and social-affective support in the teacher’s feedback enabling processes, as well as skill development of generating peer feedback and awareness enhancement in accepting critical feedback with a positive attitude. Our analysis revolves around generic and contextually grounded strategies in cognitive scaffolding and social-affective support, as well as how verbal peer feedback can be utilised as a productive solution to mitigate resource constraints. The paper concludes by highlighting the centrality of the ‘enabling construct’ of teacher feedback literacy and drawing implications for research, policy and practice.postprin

    Which colour do you want for your cells, pink or blue? -Improving the synthesis of cyanine dyes

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    Cyanine dyes are fluorescent compounds commonly used in biosensors because of their great compatibility in vivo and high extinction coefficient, which has made it the perfect choice for our previous studies investigations into prostate cancer. Although cyanine dyes are commercially available, they are very expensive with only few suppliers and problematic synthesis. To facilitate our cancer research projects, we have sought to develop improved synthetic routes to these useful compounds. In this presentation I will describe our work towards the improved synthesis of some of the cyanine dyes, Cy3 and Cy5. The difficulties (and successes) of the synthesis will be analysed and extension of these methods to other members of the family will be discussed

    Experimental and Numerical Investigation on the Irregularity of Carbonation Depth of Concrete Under Supercritical Condition

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    The heterogeneity of a cement-based material results in a random spatial distribution of carbonation depth, which may significantly affect the mechanical properties and durability of the material. Currently, there is a lack of both experimental and numerical investigations aiming at a statistical understanding of this important phenomenon. This paper presents both experimental and numerical supercritical carbonation test results of concrete blocks. The random fields of porosity and two-dimension random aggregate model of concrete were proposed for the simulation. The carbonation depths are measured and distributed along the carbonation boundary by the proposed rapid image processing technique, which are then statistically studied. The study has shown that considering the random distribution of coarse aggregates and using a random field of porosity with due consideration of spatial correlation and variance, the irregularity of carbonation depth can be realistically captured by the numerical model. Overall the methodology adopted in the paper can provide a foundation for future investigations on probability analysis of carbonation depth and other similar work based on multi-scale and –physics modelling

    Articulatory Synthesis for Data Augmentation in Phoneme Recognition

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    While numerous studies on automatic speech recognition have been published in recent years describing data augmentation strategies based on time or frequency domain signal processing, few works exist on the artificial extensions of training data sets using purely synthetic speech data. In this work, the German KIEL corpus was augmented with synthetic data generated with the state-of-the-art articulatory synthesizer VOCALTRACTLAB. It is shown that the additional synthetic data can lead to a significantly better performance in single-phoneme recognition in certain cases, while at the same time, the performance can also decrease in other cases, depending on the degree of acoustic naturalness of the synthetic phonemes. As a result, this work can potentially guide future studies to improve the quality of articulatory synthesis via the link between synthetic speech production and automatic speech recognition

    Modelling microprosodic effects can lead to an audible improvement in articulatory synthesis

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    When pitch is explicitly modelled for parametric speech synthesis, microprosodic variations of the fundamental frequency f0 are usually disregarded by current intonation models. While there are numerous studies dealing with the nature and the origin of microprosody, little research has been done on its audibility and its effect on the naturalness of synthetic speech. In this work, the influence of obstruent-related microprosodic variations on the perceived naturalness of articulatory speech synthesis was studied. A small corpus of 20 German words and sentences was re-synthesized using the state-of-the-art articulatory synthesizer VocalTractLab. The pitch contours of the real utterances were extracted and fitted with the Target-Approximation-Model. After the real microprosodic variations were removed from the obtained pitch contours, synthetic variations were applied based on a microprosody model. Subsequently, multiple stimuli with different microprosody amplitudes were synthesized and evaluated in a listening experiment. The results indicate that microprosodic variations are barely audible, but can lead to a greater perceived naturalness of the synthesized speech in certain cases

    A mathematical programming approach to multi-attribute decision making with interval-valued intuitionistic fuzzy assessment information

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    This article proposes an approach to handle multi-attribute decision making (MADM) problems under the interval-valued intuitionistic fuzzy environment, in which both assessments of alternatives on attributes (hereafter, referred to as attribute values) and attribute weights are provided as interval-valued intuitionistic fuzzy numbers (IVIFNs). The notion of relative closeness is extended to interval values to accommodate IVIFN decision data, and fractional programming models are developed based on the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method to determine a relative closeness interval where attribute weights are independently determined for each alternative. By employing a series of optimization models, a quadratic program is established for obtaining a unified attribute weight vector, whereby the individual IVIFN attribute values are aggregated into relative closeness intervals to the ideal solution for final ranking. An illustrative supplier selection problem is employed to demonstrate how to apply the proposed procedure
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