310 research outputs found

    Mechanisms of force-mediated regulation of transcription, chromatin remodeling and cell fate decisions

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    Tissue mechanics and cellular interactions influence every single cell in our bodies to drive morphogenesis. However, little is known about mechanisms by which cells sense physical forces and transduce them from the cytoskeleton to the nucleus to control gene expression and stem cell fate. We have identified a novel nuclear-mechanosensor complex, consisting of the nuclear membrane protein emerin (Emd), actin and non-muscle myosin IIA (NMIIA), that regulates transcription, chromatin remodeling and lineage commitment. Force-induced enrichment of Emd at the outer nuclear membrane leads to a compensation between H3K9me2,3 and H3K27me3 on constitutive heterochromatin. This strain-induced epigenetic switch is accompanied by the global rearrangement of chromatin. In parallel, forces promote local F-actin polymerization at the outer nuclear membrane, which limits the availability of nuclear G-actin. Subsequently, the reduction of nuclear G-actin results in attenuated global transcription and therefore increased H3K27me3 occupancy to reinforce gene silencing. Restoring nuclear actin levels in the presence of mechanical strain counteracts PRC2-mediated silencing of transcribed genes. This mechanosensory circuit is also observed in vivo. Depletion of NMIIA in mouse epidermis leads to decreased H3K27me3 levels and precocious lineage commitment, thus abrogating organ growth and patterning. Our results reveal how mechanical signals regulate nuclear architecture, chromatin organization and transcription to control cell fate decisions

    Spectroscopic measurements of sub-and supersonic plasma flows for the investigation of atmospheric re-entry shock layer radiation

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    During planetary atmospheric entries, thermochemical non-equilibrium processes in the shock layer limit the reliability of aerothermal environment prediction. To improve prediction accuracy, non-equilibrium kinetic models are being developed. These models are experimentally assessed through the comparison with well characterized non-equilibrium experiments. For this purpose, the present work is dedicated to the thermodynamic characterization of non-equilibrium in high enthalpy reactive flows. Conversely to common studies that employ short duration facilities to investigate shock layer kinetics, we will assess the possibility of producing significant departure from equilibrium using radio-frequency and microwave stationary plasma flows, including supersonic plasma flows where vibrational non-equilibrium is strongly expected. Suitable spectroscopic diagnostics have been applied allowing future comparisons to be made between the microscopic description of the experiments and theoretical non-equilibrium models.Lors des rentrées atmosphériques, les processus thermochimiques hors équilibre dans la couche de choc limitent la fiabilité des prédictions aérothermiques. Afin d'améliorer l'exactitude de ces prévisions, des modèles cinétiques sont actuellement développés. Ces modèles sont expérimentalement évalués à l'aide d'expériences dans lesquelles un départ à l'équilibre thermodynamique est caractérisé. Pour cette raison, le présent travail est consacré à la caractérisation du déséquilibre thermodynamique au sein d'écoulements réactifs à haute enthalpie. La plupart des études expérimentales dédiées à la validation de modèles cinétiques à haute température emploient des installations communément appelées tubes à choc. Nous évaluons ici la possibilité de générer un départ significatif à l'équilibre thermodynamique dans des écoulements plasma stationnaires, incluant des jets supersoniques dans lesquels le déséquilibre vibrationnel est fortement attendu. Des diagnostics spectroscopiques appropriés ont été appliqués, permettant de futures comparaisons avec des descriptions microscopiques issue de modèles théoriques

    A Planning Experimental Investigation on Tobacco Leaves Dryer Using Paddy Husk and Coal

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    In Viet Nam, the drying technology and techniques for tobacco leaves is one of the most difficulties and plays as key point to get high economic efficiency in tobacco production. To drying for tobacco leaves of 3,500 hectare, for example in Gia Lai province, there needs about 3000 dryers and there is more than 100,000 cubic meter of wood have been burned for drying which equivalent to more than 300 hectare of forest is deforested annually. A designing and manufacturing study for new tobacco dryer to replace the wood fuel by paddy-husk or coal-wood has been implemented. The results indicate that the new dryer using rice-husk or coal can be replaced for the actual drying system used fire wood with the high quality of tobacco leaves and high efficiency. The planning experimental investigation has found the function of the rate of energy consumption and the quality of drying products successfu

    Diversity of plant-parasitic nematodes on medicinal plants in Melinh station for biodiversity, Vinh Phuc Province, Vietnam

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    Plant-parasitic nematodes are known as one of the most important pests attacking various plants in the world, and investigating the nematode component is very essential for management of this pest and prevent damage to plants in general. Our survey of plant-parasitic nematodes on medicinal plants in Melinh Station for Biodiversity, a place for conservation of precious plants and animals in Vietnam, identified ten species that belong to nine genera, five families, and two orders of plant-parasitic nematodes parasitizing six medicinal plants. Excoecaria cochinchinensis was parasitized by the highest number of nematode genera (5 genera, including Xiphinema, Discocriconemella, Meloidogyne, Helicotylenchus, and Hemicriconemoides), while Hymenocallis littoralis was associated with the highest number of plant-parasitic nematodes (2060 nematodes/250g soil). The results also showed that Discocriconemella limitanea was found to be a dominant species with the highest number of individuals on 6 medicinal plants, and the genus Helicotylenchus had the highest frequency of appearance (5/6 plants or 83.3%). These nematodes caused symptoms such as yellowing leaves, root galls, and root lesions, which directly affect the quality and yield of medicinal plants. Based on the results, this study showed that plant-parasitic nematodes are a potential threat to the cultivation of medicinal plants in Melinh Station for Biodiversity, and thus, control measures should be applied to ensure sustainable cultivation of medicinal plants in this place

    Arbitrage and asset market equilibrium in infinite dimensional economies with risk-averse expected utilities

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    We consider a model with an infinite numbers of states of nature, von Neumann - Morgenstern utilities and where agents have different prob- ability beliefs. We show that no-arbitrage conditions, defined for finite dimensional asset markets models, are not sufficient to ensure existence of equilibrium in presence of an infinite number of states of nature. How- ever, if the individually rational utility set U is compact, we obtain an equilibrium. We give conditions which imply the compactness of U. We give examples of non-existence of equilibrium when these conditions do not hold

    Revisiting the Approaches for Exploring Students’ Drive in Japanese Studies

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    Japanese Studies undergraduate programs offer students an engaging curriculum that provides a deep understanding of the Japanese language and culture. A degree in Japanese Studies equips students with valuable skills that are relevant in various fields, making it a popular choice worldwide. College students’ motivation is a critical factor in academic success and has been extensively studied in education. The paper aims to review the existing theories related to study motivation, language acquisition, study abroad drives, and motivation, then to consider the approaches and details that we could prioritize for investigating the motivations and drives of students majoring and minoring in Japanese Studies in universities

    The use of Vietnamese in English phonology classes: Voices from tertiary teachers and students

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    Using the mother tongue (L1) to improve four English language skills, namely listening, reading, writing, and speaking for English as a Foreign Language (EFL) students, and to enhance their understanding and learning process has been investigated throughout the years. However, very few studies focus on the context of Vietnamese as the L1 in a course related to English language components such as an English phonology course. Therefore, this research focuses on the use of Vietnamese by lecturers and students in this course. Specifically, the study explores teachers’ and students’ perceptions of using Vietnamese and how they used it in these courses. A five-point Likert scale questionnaire was distributed to 238 students majoring in English language studies at one of the universities in Vietnam to determine their perception and practice. Meanwhile, semi-structured interviews were also conducted with five lecturers of an English phonology course. The data from the questionnaire was analyzed descriptively and thematic analysis was used to analyze the responses from the interviews. The findings revealed that all the lecturers and students used Vietnamese primarily for academic purposes, strongly supporting its use in an English Phonology class. The results also showed that L1 played an important role in learning and teaching. In addition, students showed considerably positive attitudes towards the use of Vietnamese in this classroom context. The study provides some suggestions to enhance the use of L1 in classes related to English language components, and recommendations for future research

    STUDY OF NEGATIVE REFRACTIVE INDEX IN Rb FOUR-LEVEL N-TYPE ATOMIC GAS MEDIUM

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    In this work, we study the generation of a negative refractive index based on electromagnetically induced transparency (EIT) in a Rb four-level N-type atomic gas medium. We derive analytic expressions for the relative permittivity and relative permeability of the medium according to the parameters of the probe, pump, and signal laser fields. We then investigate the variation of the real parts of the relative permittivity and relative permeability with respect to the intensity and frequency of the pump and signal laser fields. In the presence of the pump laser beam, the medium becomes transparent to the probe laser beam even in the resonant region. At the same time, the real parts of the relative permittivity and relative permeability are simultaneously negative (i.e., the medium exhibits a negative refractive index) in the EIT spectral domain. In the presence of the signal laser beam, the EIT effect occurs over two different frequency domains of the probe beam, so a negative refractive index is also generated in these two frequency domains. The investigation of the real parts of the relative permittivity and relative permeability with intensity and frequency of the pump and signal laser fields allowed us to find the laser parameters for the appearance of the negative refractive index, which can be useful for experimental observations

    Enhancing Few-shot Image Classification with Cosine Transformer

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    This paper addresses the few-shot image classification problem, where the classification task is performed on unlabeled query samples given a small amount of labeled support samples only. One major challenge of the few-shot learning problem is the large variety of object visual appearances that prevents the support samples to represent that object comprehensively. This might result in a significant difference between support and query samples, therefore undermining the performance of few-shot algorithms. In this paper, we tackle the problem by proposing Few-shot Cosine Transformer (FS-CT), where the relational map between supports and queries is effectively obtained for the few-shot tasks. The FS-CT consists of two parts, a learnable prototypical embedding network to obtain categorical representations from support samples with hard cases, and a transformer encoder to effectively achieve the relational map from two different support and query samples. We introduce Cosine Attention, a more robust and stable attention module that enhances the transformer module significantly and therefore improves FS-CT performance from 5% to over 20% in accuracy compared to the default scaled dot-product mechanism. Our method performs competitive results in mini-ImageNet, CUB-200, and CIFAR-FS on 1-shot learning and 5-shot learning tasks across backbones and few-shot configurations. We also developed a custom few-shot dataset for Yoga pose recognition to demonstrate the potential of our algorithm for practical application. Our FS-CT with cosine attention is a lightweight, simple few-shot algorithm that can be applied for a wide range of applications, such as healthcare, medical, and security surveillance. The official implementation code of our Few-shot Cosine Transformer is available at https://github.com/vinuni-vishc/Few-Shot-Cosine-Transforme

    Pulse Rate Analysis in Case of Central Sleep Apnea: A New Algorithm for Cardiac Rate Estimation

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    Annual International Conference of the IEEEInternational audienceThis paper first describes the AM-FM demodulation of an arterial pressure signal. Although it is known to be efficient on signals modulated by breathing, we demonstrate that in case of lack of respiratory modulation (central sleep apnea), the AM-FM algorithm doesn't perform well in heart rate extraction. We introduce then a new algorithm based on Singular Spectrum Analysis eigen values which performs better cardiac frequency estimation in this context. The error for cardiac frequency estimation is around 0.2 BPM (Beats Per Minute) versus 5.5 BPM for the AM-FM demodulation. Further experimentations will be performed (with this time both cardiac and respiratory assessments) and will deal with real sleep apnea cases
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