5,096 research outputs found

    On-line monitoring of the transesterification reaction between triglycerides and ethanol using near infrared spectroscopy combined with gas chromatography

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    Many analytical procedures have been developed to determine the composition of reaction mixtures during transesterification of vegetable oils with alcohols. However, despite their accuracy, these methods are time consuming and cannot be easily used for on-line monitoring. In this work, a fast analytical method was developed to on-line monitor the transesterification reaction of high oleic sunflower oil with ethanol using Near InfraRed spectroscopy and a multivariate approach. The reactions were monitored through sequential scans of the reaction medium with a probe in a one-liter batch reactor without collecting and preparing samples. To calibrate the NIR analytical method, gas chromatography-flame ionization detection was used as a reference method. The method was validated by studying the kinetics of the EtONa-catalyzed transesterification reaction. Activation energy (51.0 kJ/mol) was also determined by considering a pseudo second order kinetics model

    The rr-coloring and maximum stable set problem in hypergraphs with bounded matching number and edge size

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    Motivated by the analogous questions in graphs, we study the complexity of coloring and stable set problems in hypergraphs with forbidden substructures and bounded edge size. Letting ν(G)\nu(G) denote the maximum size of a matching in HH, we obtain complete dichotomies for the complexity of the following problems parametrized by fixed r,k,s∈Nr, k, s \in \mathbb{N}: rr-Coloring in hypergraphs GG with edge size at most kk and ν(G)≤s\nu(G) \leq s; rr-Precoloring Extension in kk-uniform hypergraphs GG with ν(G)≤s\nu(G) \leq s; rr-Precoloring Extension in hypergraphs GG with edge size at most kk and ν(G)≤s\nu(G) \leq s; Maximum Stable Set in kk-uniform hypergraphs GG with ν(G)≤s\nu(G) \leq s; Maximum Weight Stable Set in kk-uniform hypergraphs with ν(G)≤s\nu(G) \leq s; as well as partial results for rr-Coloring in kk-uniform hypergraphs ν(G)≤s\nu(G) \leq s. We then turn our attention to 22-Coloring in 3-uniform hypergraphs with forbidden induced subhypergraphs, and give a polynomial-time algorithm when restricting the input to hypergraphs excluding a fixed one-edge hypergraph. Finally, we consider linear 3-uniform hypergraphs (in which every two edges share at most one vertex), and show that excluding an induced matching in GG implies that ν(G)\nu(G) is bounded by a constant; and that 33-coloring linear 33-uniform hypergraphs GG with ν(G)≤532\nu(G) \leq 532 is NP-hard

    Repurposing Pillar One into An Incremental Global Tax for Sustainability: Some Blue Sky Thinking in the Midst of Global Crisis

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    In this article, the authors make a case for repurposing the OECD Pillar One from a mechanism for reallocating taxing rights to a global tax on the largest and most profitable MNEs’ market-based profits. Such global tax would have the hybrid features of a net-basis corporate income tax and a turnover-basis digital services tax through a conversion formula that ensures a low-rate DST on sales can replicate a higher rate CIT on a country’s share of the profit determined using under the formulary allocation method. More importantly, the authors instill a common purpose of the international tax consensus – to help finance spending on achieving the UN Sustainable Development Goals and targets committed in the Paris Agreement. They also argue that the repurposed Pillar One would be a win, win, win proposition for governments, MNEs and the Planet

    Mistral and Tramontane wind speed and wind direction patterns in regional climate simulations

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    International audienceThe Mistral and Tramontane are important wind phenomena that occur over southern France and the northwestern Mediterranean Sea. Both winds travel through constricting valleys before flowing out towards the Mediterranean Sea. The Mistral and Tramontane are thus interesting phenomena, and represent an opportunity to study channeling effects, as well as the interactions between the atmosphere and land/ocean surfaces. This study investigates Mistral and Tramontane simulations using five regional climate models with grid spacing of about 50 km and smaller. All simulations are driven by ERA-Interim reanalysis data. Spatial patterns of surface wind, as well as wind development and error propagation along the wind tracks from inland France to offshore during Mistral and Tramontane events, are presented and discussed. To disentangle the results from large-scale error sources in Mistral and Tramontane simulations, only days with well simulated large-scale sea level pressure field patterns are evaluated. Comparisons with the observations show that the large-scale pressure patterns are well simulated by the considered models, but the orographic modifications to the wind systems are not well simulated by the coarse-grid simulations (with a grid spacing of about 50 km), and are reproduced slightly better by the higher resolution simulations. On days with Mistral and/or Tramontane events, most simulations underestimate (by 13 % on average) the wind speed over the Mediterranean Sea. This effect is strongest at the lateral borders of the main flow—the flow width is underestimated. All simulations of this study show a clockwise wind direction bias over the sea during Mistral and Tramontane events. Simulations with smaller grid spacing show smaller biases than their coarse-grid counterparts

    Investigating gait-responsive somatosensory cueing from a wearable device to improve walking in Parkinson’s disease

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    Freezing-of-gait (FOG) and impaired walking are common features of Parkinson’s disease (PD). Provision of external stimuli (cueing) can improve gait, however, many cueing methods are simplistic, increase task loading or have limited utility in a real-world setting. Closed-loop (automated) somatosensory cueing systems have the potential to deliver personalised, discrete cues at the appropriate time, without requiring user input. Further development of cue delivery methods and FOG-detection are required to achieve this. In this feasibility study, we aimed to test if FOG-initiated vibration cues applied to the lower-leg via wearable devices can improve gait in PD, and to develop real-time FOG-detection algorithms. 17 participants with Parkinson’s disease and daily FOG were recruited. During 1 h study sessions, participants undertook 4 complex walking circuits, each with a different intervention: continuous rhythmic vibration cueing (CC), responsive cueing (RC; cues initiated by the research team in response to FOG), device worn with no cueing (NC), or no device (ND). Study sessions were grouped into 3 stages/blocks (A-C), separated by a gap of several weeks, enabling improvements to circuit design and the cueing device to be implemented. Video and onboard inertial measurement unit (IMU) data were analyzed for FOG events and gait metrics. RC significantly improved circuit completion times demonstrating improved overall performance across a range of walking activities. Step frequency was significantly enhanced by RC during stages B and C. During stage C, > 10 FOG events were recorded in 45% of participants without cueing (NC), which was significantly reduced by RC. A machine learning framework achieved 83% sensitivity and 80% specificity for FOG detection using IMU data. Together, these data support the feasibility of closed-loop cueing approaches coupling real-time FOG detection with responsive somatosensory lower-leg cueing to improve gait in PD

    Kinetin induces microtubular breakdown, cell cycle arrest and programmed cell death in tobacco BY-2 cells

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    Plant cells can undergo regulated cell death in response to exogenous factors (often in a stress context), but also as regular element of development (often regulated by phytohormones). The cellular aspects of these death responses differ, which implies that the early signalling must be different. We use cytokinin-induced programmed cell death as paradigm to get insight into the role of the cytoskeleton for the regulation of developmentally induced cell death, using tobacco BY-2 cells as experimental model. We show that this PCD in response to kinetin correlates with an arrest of the cell cycle, a deregulation of DNA replication, a loss of plasma membrane integrity, a subsequent permeabilisation of the nuclear envelope, an increase of cytosolic calcium correlated with calcium depletion in the culture medium, an increase of callose deposition and the loss of microtubule and actin integrity. We discuss these findings in the context of a working model, where kinetin, mediated by calcium, causes the breakdown of the cytoskeleton, which, either by release of executing proteins or by mitotic catastrophe, will result in PCD

    Lessons from Formally Verified Deployed Software Systems (Extended version)

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    The technology of formal software verification has made spectacular advances, but how much does it actually benefit the development of practical software? Considerable disagreement remains about the practicality of building systems with mechanically-checked proofs of correctness. Is this prospect confined to a few expensive, life-critical projects, or can the idea be applied to a wide segment of the software industry? To help answer this question, the present survey examines a range of projects, in various application areas, that have produced formally verified systems and deployed them for actual use. It considers the technologies used, the form of verification applied, the results obtained, and the lessons that can be drawn for the software industry at large and its ability to benefit from formal verification techniques and tools. Note: a short version of this paper is also available, covering in detail only a subset of the considered systems. The present version is intended for full reference.Comment: arXiv admin note: text overlap with arXiv:1211.6186 by other author

    Current Status and Trends of Engineering Entrepreneurship Education in Australian Universities

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    This research sheds light on the present and future landscape of Engineering Entrepreneurship Education (EEE) by exploring varied approaches and models adopted in Australian universities, evaluating program effectiveness, and offering recommendations for curriculum enhancement. While EEE programs have been in existence for over two decades, their efficacy remains underexplored. Using a multi-method approach encompassing self-reflection, scoping review, surveys, and interviews, this study addresses key research questions regarding the state, challenges, trends, and effectiveness of EEE. Findings reveal challenges like resource limitations and propose solutions such as experiential learning and industry partnerships. These insights underscore the importance of tailored EEE and inform teaching strategies and curriculum development, benefiting educators and policymakers worldwide

    ER-Mitochondria contact sites : a new regulator of cellular calcium flux comes into play

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    Endoplasmic reticulum (ER)-mitochondria membrane contacts are hotspots for calcium signaling. In this issue, Raturi et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201512077) show that the thioredoxin TMX1 inhibits the calcium pump SERCA2b at ER-mitochondria contact sites, thereby affecting ER-mitochondrial calcium transfer and mitochondrial bioenergetics
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