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Estimation of behavioral user state based on eye gaze and head pose—application in an e-learning environment 总被引:1,自引:1,他引:0
Stylianos Asteriadis Paraskevi Tzouveli Kostas Karpouzis Stefanos Kollias 《Multimedia Tools and Applications》2009,41(3):469-493
Most e-learning environments which utilize user feedback or profiles, collect such information based on questionnaires, resulting
very often in incomplete answers, and sometimes deliberate misleading input. In this work, we present a mechanism which compiles
feedback related to the behavioral state of the user (e.g. level of interest) in the context of reading an electronic document;
this is achieved using a non-intrusive scheme, which uses a simple web camera to detect and track the head, eye and hand movements
and provides an estimation of the level of interest and engagement with the use of a neuro-fuzzy network initialized from
evidence from the idea of Theory of Mind and trained from expert-annotated data. The user does not need to interact with the
proposed system, and can act as if she was not monitored at all. The proposed scheme is tested in an e-learning environment,
in order to adapt the presentation of the content to the user profile and current behavioral state. Experiments show that
the proposed system detects reading- and attention-related user states very effectively, in a testbed where children’s reading
performance is tracked.
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Stefanos KolliasEmail: |
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An Adaptive Neuro-fuzzy Inference System for Robot Handling Fabrics with Curved Edges towards Sewing
Paraskevi Th. Zacharia 《Journal of Intelligent and Robotic Systems》2010,58(3-4):193-209
This paper presents the design of a neuro-fuzzy visual servoing controller for robot guiding fabrics with curved edges towards sewing. Fabrics comprising real cloths consist of curved edges of arbitrary curvatures that can not be standardized. To overcome this difficulty, the idea is to train the robot sewing system and to apply this methodology in a real-time operation environment. The proposed approach for robot sewing is based on visual servoing and a learning technique that combines neural networks and fuzzy logic. A novel genetic-oriented clustering method is used to construct the initial FIS models and then, adaptive neuro-fuzzy inference systems allow tuning them so that it is possible to obtain better estimates. Extensive experiments were carried out in order to build data sets using fabrics with curved edges of various curvatures. The proposed model is validated using fabrics that had not been included in the training process and the results demonstrate that the proposed approach is efficient and effective for robot guiding fabrics with arbitrary curved edges towards sewing. 相似文献
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Elisabeth A. A. O'Flaherty Paraskevi Tsermoula Eileen E. O'Neill Nora M. O'Brien 《International Journal of Food Science & Technology》2019,54(4):1256-1264
Beef processing produces high volumes of protein rich, low value, ‘waste’ co-products such as offal. Beef improves uptake of low bioavailable non-haem iron (found in vegetables, fortificants, supplements) and this effect is dubbed the ‘meat-factor’, although the underlying mechanism is not fully understood. Here, we investigate whether bovine co-products (kidney, lung, heart) not previously studied share this enhancing potential. This was determined by coupled in vitro digestion of co-products and subsequent caco-2 cell ferritin formation (an intracellular iron storage protein). In this study we show that bovine co-products significantly increase caco-2 cells’ response to non-haem iron from infant rice cereal. The presence of these co-products, (kidney, lung and heart), increased relative uptake (by 207.13%, 171.21%, 265.28%, respectively), to a greater extent than beef (30.23%). Our findings present a novel function for co-products of beef processing that may have potential as food ingredients to improve non-haem iron bioavailability, thus adding value. 相似文献
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Evangelos I. Manolas Stilianos A. Tampakis Paraskevi P. Karanikola 《The International journal of environmental studies》2013,70(4):599-609
The trend to global warming is one of the most important problems of our time. This paper reports the findings of self‐management questionnaires, in regard to views held on the issue of climate change by the students of the Department of Forestry and Management of the Environment and Natural Resources of the Democritus University of Thrace. 相似文献
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Paraskevi Malea Danae Kokkinidi Alkistis Kevrekidou Ioannis-Dimosthenis S. Adamakis 《International journal of molecular sciences》2022,23(3)
The effects of environmentally relevant bisphenol A (BPA) concentrations (0.3, 1 and 3 μg L−1) were tested at 2, 4, 6 and 8 days, on intermediate leaves, of the seagrass Cymodocea nodosa. Hydrogen peroxide (H2O2) production, lipid peroxidation, protein, phenolic content and antioxidant enzyme activities were investigated. Increased H2O2 formation was detected even at the lowest BPA treatments from the beginning of the experiment and both the enzymatic and non-enzymatic antioxidant defense mechanisms were activated upon application of BPA. Elevated H2O2 levels that were detected as a response to increasing BPA concentrations and incubation time, led to the decrease of protein content on the 4th day even at the two lower BPA concentrations, and to the increase of the lipid peroxidation at the highest concentration. However, on the 6th day of BPA exposure, protein content did not differ from the control, indicating the ability of both the enzymatic and non-enzymatic mechanisms (such as superoxide dismutase (SOD) and phenolics) to counteract the BPA-derived oxidative stress. The early response of the protein content determined that the Low Effect Concentration (LOEC) of BPA is 0.3 μg L−1 and that the protein content meets the requirements to be considered as a possible early warning “biomarker” for C. nodosa against BPA toxicity. 相似文献
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Proportional delay differentiation provision by bandwidth adaptation of class‐based queue scheduling
Angelos Michalas Malamati Louta Paraskevi Fafali George Karetsos Vassilios Loumos 《International Journal of Communication Systems》2004,17(7):743-761
Supporting quality of service (QoS) over the Internet is a very important issue and many mechanisms have already been devised or are under way towards achieving this goal. One of the most important approaches is the so‐called Differentiated Services (DiffServ) architecture, which provides a scalable mechanism for QoS support in a TCP/IP network. The main concept underlying DiffServ is the aggregation of traffic flows at an ingress (or egress) point of a network and the marking of the IP packets of each traffic flow according to several classification criteria. Diffserv is classified under two taxonomies: the absolute and the relative. In absolute DiffServ architecture, an admission control scheme is utilized to provide QoS as absolute bounds of specific QoS parameters. The relative DiffServ model offers also QoS guarantees per class but in reference to the guarantees given to the other classes defined. In this paper, relative proportional delay differentiation is achieved based on class‐based queueing (CBQ) scheduler. Specifically, the service rates allocated to the classes of a CBQ scheduler are frequently adjusted in order to obtain relative delay spacing among them. The model presented can also be exploited in order to meet absolute delay constraints in conjunction with relative delay differentiation provision. Simulation experiments verify that our model can attain relative as well as absolute delay differentiation provided that the preconditions posed are satisfied. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Ioanna Nikitopoulou Aggeliki Katsifa Paraskevi Kanellopoulou Edison Jahaj Alice G. Vassiliou Zafeiria Mastora Ioanna Dimopoulou Stylianos E. Orfanos Vassilis Aidinis Anastasia Kotanidou 《International journal of molecular sciences》2022,23(14)
The pathogenesis of sepsis involves complex interactions and a systemic inflammatory response leading eventually to multiorgan failure. Autotaxin (ATX, ENPP2) is a secreted glycoprotein largely responsible for the extracellular production of lysophosphatidic acid (LPA), which exerts multiple effects in almost all cell types through its at least six G-protein-coupled LPA receptors (LPARs). Here, we investigated a possible role of the ATX/LPA axis in sepsis in an animal model of endotoxemia as well as in septic patients. Mice with 50% reduced serum ATX levels showed improved survival upon lipopolysaccharide (LPS) stimulation compared to their littermate controls. Similarly, mice bearing the inducible inactivation of ATX and presenting with >70% decreased ATX levels were even more protected against LPS-induced endotoxemia; however, no significant effects were observed upon the chronic and systemic transgenic overexpression of ATX. Moreover, the genetic deletion of LPA receptors 1 and 2 did not significantly affect the severity of the modelled disease, suggesting that alternative receptors may mediate LPA effects upon sepsis. In translation, ATX levels were found to be elevated in the sera of critically ill patients with sepsis in comparison with their baseline levels upon ICU admission. Therefore, the results indicate a role for ATX in LPS-induced sepsis and suggest possible therapeutic benefits of pharmacologically targeting ATX in severe, systemic inflammatory disorders. 相似文献
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