274 research outputs found
Twist Three Distribution f_\perp(x,k^\perp) in Light-front Hamiltonian Approach
We calculate the twist three distribution f_\perp(x,k^\perp) contributing to
Cahn effect in unpolarized semi-inclusive deep inelastic scattering. We use
light-front Hamiltonian technique and take the state to be a dressed quark at
one loop in perturbation theory. The 'genuine twist three' contribution comes
from the quark-gluon interaction part in the operator and is explicitly
calculated. f_\perp(x,k^\perp) is compared with f_1(x,k^\perp).Comment: Two figures added, one author added, some parts rewritten for
clarificatio
Adaptive Inverse Dynamics Control Scheme of Two-Compartment Lung System
University of Minnesota M.S.E.E. thesis. March 2017. Major: Electrical Engineering. Advisor: Jiann Shiou Yang. 1 computer file (PDF); iv, 55 pages.A study of using an adaptive inverse dynamics control technique to a two-compartment modeled respiratory system. Based on the nonlinear respiratory model and desired respiratory volumes, the adaptive inverse dynamics control scheme consisting of a control law and an adaptation law is then applied. The control law has the structure of the two-compartment inverse dynamical model but uses estimates of the dynamics parameters in the computation of pressure applied to the lungs. The adaptation law uses the tracking error to compute the parameter estimates for the control law. The preliminary results indicate that the tracking errors can be improved if the parameter values associated with the adaptation law are properly chosen, and the performance is also robust despite relatively large deviations in the initial estimates of the system parameter
GMR-29 Identification of AI-Generated Images
With the quick rise of Artificial Intelligence (AI), generative AI models have greatly increased the volume and velocity of data creation. Among that data, AI-generated images have become a highly discussed topic, especially when discussing the potential dangers of these AI models. Due to these dangers, being able to distinguish AI-generated art from human-made art is becoming a necessity. Additionally, as these AI-models improve, it is becoming increasingly difficult for humans to determine whether art is AI-generated or human-made. This paper proposes the further exploration of the effectiveness of a current state of the art AI-image identification model
"The Institut Pascal Data Sets" : un jeu de données en extérieur, multicapteurs et datées avec réalité terrain, données d'étalonnage et outils logiciels
National audienceLa mise à disposition au public de jeux de données permet des progrès conséquents pour la validation des travaux de recherche. Nous présentons dans cet article un jeu de données multi-capteurs acquises sur un campus. L'Institut Pascal DataSets peut être utilisé dans une large variété d'applications robotiques et de traitement d'images. Il inclut entre autres une réalité terrain fournie par un GPS centimétrique et des images panoramiques couleur. Sont également fournies des séquences additionnelles pour des phases d'étalonnage, des données a priori ainsi que des outils logiciels
The Effects Of Electronic Cigarette Components On Female Fertility And Associated Prenatal Period.
AbstractOver the past decade, there has been an alarming rate of increase in the usage of electronic cigarettes also known as vaping. The misapprehension that such alternative nicotine products are less harmful than conventional cigarettes has attracted vulnerable population groups which include middle and high-school students ,young adults, women with the desire to conceive and childbearing mothers who look for combustible cigarette replacements during gestational period. Vaping devices deliver nicotine-containing aerosols by heating e-fluids that have proven to be cytotoxic and teratogenic, justifying maternal vaping as a frequent cause of morbidity in the fetus. As a part of this study, we aim to develop a greater understanding of the consequences of e-cigarettes consumption in women of reproductive age and exposed fetuses.Keywords- Electronic cigarettes, teratogenic, maternal vaping, fetuse
Efficacy of frog skin lipids in wound healing
<p>Abstract</p> <p>Background</p> <p>Frog skin has been sequentially and scientifically evaluated by our group for its wound healing efficiency. Owing to the complex structure of skin, attempts were being made to analyse the role of individual constituents in different phases of healing. Our earlier papers have shown the significance of frog skin not only in wound healing but also enhancing the proliferating activity of the epidermal and dermal cells which are instrumental for normal healing process. We also have identified for the first time novel antimicrobial peptides from the skin of <it>Rana tigerina </it>and thereby reduce the complications involved in the sepsis.</p> <p>Purpose of the study and Results</p> <p>The current study envisages the role of frog skin lipids in the inflammatory phase of wound healing. The lipid moiety of the frog skin dominated by phospholipids exhibited a dose dependent acceleration of healing irrespective of the mode of application. The efficiency of the extract is attributed partially to the anti-inflammatory activity as observed by the histochemical and immunostimulatory together with plethysmographic studies.</p> <p>Conclusions</p> <p>Thus, frog skin for the first time has been demonstrated to possess lipid components with pharmaceutical and therapeutic potential. The identification and characterization of such natural healing molecules and evaluating their mechanism of action would therefore provide basis for understanding the cues of Nature and hence can be used for application in medicine.</p
Loop closure for topological mapping and navigation with omnidirectional images
Dans le cadre de la robotique mobile, des progrès significatifs ont été obtenus au cours des trois dernières décennies pour la cartographie et la localisation. La plupart des projets de recherche traitent du problème de SLAM métrique. Les techniques alors développées sont sensibles aux erreurs liées à la dérive ce qui restreint leur utilisation à des environnements de petite échelle. Dans des environnements de grande taille, l utilisation de cartes topologiques, qui sont indépendantes de l information métrique, se présentent comme une alternative aux approches métriques.Cette thèse porte principalement sur le problème de la construction de cartes topologiques pour la navigation de robots mobiles dans des environnements urbains de grande taille, en utilisant des caméras omnidirectionnelles. La principale contribution de cette thèse est la résolution efficace et avec précision du problème de fermeture de boucles, problème qui est au coeur de tout algorithme de cartographie topologique. Le cadre de cartographie topologique éparse / hiérarchique proposé allie une approche de partionnement de séquence d images (ISP) par regroupement des images visuellement similaires dans un noeud avec une approche de détection de fermeture de boucles permettant de connecter ces noeux. Le graphe topologique alors obtenu représente l environnement du robot. L algorithme de fermeture de boucle hiérarchique développé permet d extraire dans un premier temps les noeuds semblables puis, dans un second temps, l image la plus similaire. Cette détection de fermeture de boucles hiérarchique est rendue efficace par le stockage du contenu des cartes éparses sous la forme d une structure de données d indexation appelée fichier inversé hiérarchique (HIF). Nous proposons de combiner le score de pondération TFIDF avec des contraintes spatiales et la fréquence des amers détectés pour obtenir une meilleur robustesse de la fermeture de boucles. Les résultats en terme de densité et précision des cartes obtenues et d efficacité sont évaluées et comparées aux résultats obtenus avec des approches de l état de l art sur des séquences d images omnidirectionnelles acquises en milieu extérieur. Au niveau de la précision des détections de boucles, des résultats similaires ont été observés vis-à-vis des autres approches mais sans étape de vérification utilisant la géométrie épipolaire. Bien qu efficace, l approche basée sur HIF présente des inconvénients comme la faible densité des cartes et le faible taux de détection des boucles. Une seconde technique de fermeture de boucle a alors été développée pour combler ces lacunes. Le problème de la faible densité des cartes est causé par un sur-partionnement de la séquence d images. Celui-ci est résolu en utilisant des vecteurs de descripteurs agrégés localement (VLAD) lors de l étape de ISP. Une mesure de similarité basée sur une contrainte spatiale spécifique à la structure des images omnidirectionnelles a également été développée. Des résultats plus précis sont obtenus, même en présence de peu d appariements. Les taux de réussite sont meilleurs qu avec FABMAP 2.0, la méthode la plus utilisée actuellement, sans étape supplémentaire de vérification géométrique.L environnement est souvent supposé invariant au cours du temps : la carte de l environnement est construite lors d une phase d apprentissage puis n est pas modifiée ensuite. Une gestion de la mémoire à long terme est nécessaire pour prendre en compte les modifications dans l environnement au cours du temps. La deuxième contribution de cette thèse est la formulation d une approche de gestion de la mémoire visuelle à long terme qui peut être utilisée dans le cadre de cartes visuelles topologiques et métriques. Les premiers résultats obtenus sont encourageants. (...)Over the last three decades, research in mobile robotic mapping and localization has seen significant progress. However, most of the research projects these problems into the SLAM framework while trying to map and localize metrically. As metrical mapping techniques are vulnerable to errors caused by drift, their ability to produce consistent maps is limited to small scale environments. Consequently, topological mapping approaches which are independent of metrical information stand as an alternative to metrical approaches in large scale environments. This thesis mainly deals with the loop closure problem which is the crux of any topological mapping algorithm. Our main aim is to solve the loop closure problem efficiently and accurately using an omnidirectional imaging sensor. Sparse topological maps can be built by representing groups of visually similar images of a sequence as nodes of a topological graph. We propose a sparse / hierarchical topological mapping framework which uses Image Sequence Partitioning (ISP) to group visually similar images of a sequence as nodes which are then connected on occurrence of loop closures to form a topological graph. A hierarchical loop closure algorithm that can first retrieve the similar nodes and then perform an image similarity analysis on the retrieved nodes is used. An indexing data structure called Hierarchical Inverted File (HIF) is proposed to store the sparse maps to facilitate an efficient hierarchical loop closure. TFIDF weighting is combined with spatial and frequency constraints on the detected features for improved loop closure robustness. Sparsity, efficiency and accuracy of the resulting maps are evaluated and compared to that of the other two existing techniques on publicly available outdoor omni-directional image sequences. Modest loop closure recall rates have been observed without using the epi-polar geometry verification step common in other approaches. Although efficient, the HIF based approach has certain disadvantages like low sparsity of maps and low recall rate of loop closure. To address these shortcomings, another loop closure technique using spatial constraint based similarity measure on omnidirectional images has been proposed. The low sparsity of maps caused by over-partitioning of the input sequence has been overcome by using Vector of Locally Aggregated Descriptors (VLAD) for ISP. Poor resolution of the omnidirectional images causes fewer feature matches in image pairs resulting in reduced recall rates. A spatial constraint exploiting the omnidirectional image structure is used for feature matching which gives accurate results even with fewer feature matches. Recall rates better than the contemporary FABMAP 2.0 approach have been observed without the additional geometric verification. The second contribution of this thesis is the formulation of a visual memory management approach suitable for long term operability of mobile robots. The formulated approach is suitable for both topological and metrical visual maps. Initial results which demonstrate the capabilities of this approach have been provided. Finally, a detailed description of the acquisition and construction of our multi-sensor dataset is provided. The aim of this dataset is to serve the researchers working in the mobile robotics and vision communities for evaluating applications like visual SLAM, mapping and visual odometry. This is the first dataset with omnidirectional images acquired on a car-like vehicle driven along a trajectory with multiple loops. The dataset consists of 6 sequences with data from 11 sensors including 7 cameras, stretching 18 kilometers in a semi-urban environmental setting with complete and precise ground-truth.CLERMONT FD-Bib.électronique (631139902) / SudocSudocFranceF
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