419 research outputs found

    Применение нейросетевых технологий для измерений параметров вибрации объектов с неплоской поверхностью

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    Было проведено компьютерное моделирование электродинамической системы интерференционного измерителя параметров вибраций объектов с неплоской поверхностью. Показано, что применение нейросетевых технологий позволяет использовать интерференционный метод для измерения параметров перемещений объектов с неплоской поверхностью. Полученные результаты обработки данных компьютерного моделирования свидетельствуют об эффективности практического применения нейронных сетей для обработки сигналов трёхзондового интерференционного сверхвысокочастотного измерителя.Було проведено комп'ютерне моделювання електродинамічної системи інтерференційного вимірювача параметрів вібрацій об'єктів з неплоскою поверхнею. Показано, що застосування нейромережевих технологій дозволяє використовувати інтерференційний метод для вимірювання параметрів переміщень об'єктів з неплоскою поверхнею. Отримані результати обробки даних комп'ютерного моделювання свідчать про ефективність практичного застосування нейронних мереж для обробки сигналів тризондового інтерференційного надвисокочастотного вимірювача.An electrodynamical system of an interference vibration meter for objects with a non-planar surface is simulated using a computer. It is shown that neural technologies allow to use an interference method for measuring parameters of the moving objects with a non-planar surface. The results obtained of processing data of a computer simulation show the effectiveness of the practical application of neural networks for processing signals of the trisounder interference microwave meter

    Seuillage d'images basé sur l'opérateur de Teager-Kaiser

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    Le seuillage de l'histogramme d'une image est une procédure classique de segmentation. Dans ce travail, on s'intéresse au problème du seuillage d'images en deux niveaux, pour extraire une information binaire pertinente. On propose une nouvelle méthode de seuillage qui inclut l'information contextuelle du pixel, en utilisant les contours pour estimer le seuil. Plus exactement, au lieu d'utiliser un détecteur de contours classique, on utilise l'Opérateur d'Énergie de Teager-Kaiser (OETK) pour mesurer l'activité en énergie du pixel. En effet, cet opérateur reflète mieux l'activité en énergie du pixel qu'un détecteur de contours classique (Laplacien,...). Les résultats obtenus sur des images synthétiques et réelles montrent l'intérêt de l'attribut du contexte. La comparaison avec les méthodes d'Otsu et de Kitler montrent l'apport de l'OETK à l'estimation du seuil

    Evidence of dynamics reversal in tropical estuaries, geomorphological and sedimentological consequences (Salum and Casamance Rivers, Senegal)

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    ABSTRACT South Dakar Senegambian estuaries are subject to an unusual hydrodynamical regime caused by weak or absent run-off. In the Salum delta, each distributary lacks fresh water during most of the year. Only the tidal flows arc responsible for geomorphological and sedimentological effects. The current distribution shows a net discharge upstream due to the extensive evaporation and evapotranspiration in mangrove swamps and tidal flats. Consequently the salinity is always higher towards the river than near the sea. A high salinity bottom layer suggests the occurrence of a supersaline wedge of reverse sense to the salt wedge of a normal estuary. Such an inverse pattern is similarly displayed by sedimentological features (double upstream tumed spits) and by the external location of the turbidity maximum. A coherent reverse estuary model is suggested from our field observations

    Thomas Decomposition and Nonlinear Control Systems

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    This paper applies the Thomas decomposition technique to nonlinear control systems, in particular to the study of the dependence of the system behavior on parameters. Thomas' algorithm is a symbolic method which splits a given system of nonlinear partial differential equations into a finite family of so-called simple systems which are formally integrable and define a partition of the solution set of the original differential system. Different simple systems of a Thomas decomposition describe different structural behavior of the control system in general. The paper gives an introduction to the Thomas decomposition method and shows how notions such as invertibility, observability and flat outputs can be studied. A Maple implementation of Thomas' algorithm is used to illustrate the techniques on explicit examples

    Water

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    Meta-analysis can be a powerful tool for demonstrating the applicability of a concept beyond the context of individual clinical trials and observational studies, including exploration of effects across different subgroups. Meta-analysis avoids Simpson's paradox, in which a consistent effect in constituent trials is reversed when results are simply pooled. Meta-analysis in critical care medicine is made more complicated, however, by the heterogeneous nature of critically ill patients and the contexts within which they are treated. Failure to properly adjust for this heterogeneity risks missing important subgroup effects in, for example, the interaction of treatment with varying levels of baseline risk. When subgroups are defined by characteristics that vary within constituent trials (such as age) rather than features constant within each trial (such as drug dose), there is the additional risk of incorrect conclusions due to the ecological fallacy. The present review explains these problems and the strategies by which they are overcome

    Ontogenic changes in hematopoietic hierarchy determine pediatric specificity and disease phenotype in fusion oncogene-driven myeloid leukemia

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    Fusion oncogenes are prevalent in several pediatric cancers, yet little is known about the specific associations between age and phenotype. We observed that fusion oncogenes, such as ETO2–GLIS2, are associated with acute megakaryoblastic or other myeloid leukemia subtypes in an age-dependent manner. Analysis of a novel inducible transgenic mouse model showed that ETO2–GLIS2 expression in fetal hematopoietic stem cells induced rapid megakaryoblastic leukemia whereas expression in adult bone marrow hematopoietic stem cells resulted in a shift toward myeloid transformation with a strikingly delayed in vivo leukemogenic potential. Chromatin accessibility and single-cell transcriptome analyses indicate ontogeny-dependent intrinsic and ETO2–GLIS2-induced differences in the activities of key transcription factors, including ERG, SPI1, GATA1, and CEBPA. Importantly, switching off the fusion oncogene restored terminal differentiation of the leukemic blasts. Together, these data show that aggressiveness and phenotypes in pediatric acute myeloid leukemia result from an ontogeny-related differential susceptibility to transformation by fusion oncogenes. SIGNIFICANCE: This work demonstrates that the clinical phenotype of pediatric acute myeloid leukemia is determined by ontogeny-dependent susceptibility for transformation by oncogenic fusion genes. The phenotype is maintained by potentially reversible alteration of key transcription factors, indicating that targeting of the fusions may overcome the differentiation blockage and revert the leukemic state

    Patients with primary immunodeficiencies are a reservoir of poliovirus and a risk to polio eradication

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    ABSTARCT: Immunodeficiency-associated vaccine-derived polioviruses (iVDPVs) have been isolated from primary immunodeficiency (PID) patients exposed to oral poliovirus vaccine (OPV). Patients may excrete poliovirus strains for months or years; the excreted viruses are frequently highly divergent from the parental OPV and have been shown to be as neurovirulent as wild virus. Thus, these patients represent a potential reservoir for transmission of neurovirulent polioviruses in the post-eradication era. In support of WHO recommendations to better estimate the prevalence of poliovirus excreters among PIDs and characterize genetic evolution of these strains, 635 patients including 570 with primary antibody deficiencies and 65 combined immunodeficiencies were studied from 13 OPV-using countries. Two stool samples were collected over 4 days, tested for enterovirus, and the poliovirus positive samples were sequenced. Thirteen patients (2%) excreted polioviruses, most for less than 2 months following identification of infection. Five (0.8%) were classified as iVDPVs (only in combined immunodeficiencies and mostly poliovirus serotype 2). Non-polio enteroviruses were detected in 30 patients (4.7%). Patients with combined immunodeficiencies had increased risk of delayed poliovirus clearance compared to primary antibody deficiencies. Usually, iVDPV was detected in subjects with combined immunodeficiencies in a short period of time after OPV exposure, most for less than 6 months. Surveillance for poliovirus excretion among PID patients should be reinforced until polio eradication is certified and the use of OPV is stopped. Survival rates among PID patients are improving in lower and middle income countries, and iVDPV excreters are identified more frequently. Antivirals or enhanced immunotherapies presently in development represent the only potential means to manage the treatment of prolonged excreters and the risk they present to the polio endgame. Keywords: Poliovirus eradication, Immunodeficiency-associated vaccine-derived polioviruses, Oral poliovirus vaccine, Humoral immunodeficiency, Combined immunodeficiency, Primary immunodeficienc

    Restriction site polymorphism-based candidate gene mapping for seedling drought tolerance in cowpea [Vigna unguiculata (L.) Walp.]

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    Quantitative trait loci (QTL) studies provide insight into the complexity of drought tolerance mechanisms. Molecular markers used in these studies also allow for marker-assisted selection (MAS) in breeding programs, enabling transfer of genetic factors between breeding lines without complete knowledge of their exact nature. However, potential for recombination between markers and target genes limit the utility of MAS-based strategies. Candidate gene mapping offers an alternative solution to identify trait determinants underlying QTL of interest. Here, we used restriction site polymorphisms to investigate co-location of candidate genes with QTL for seedling drought stress-induced premature senescence identified previously in cowpea. Genomic DNA isolated from 113 F2:8 RILs of drought-tolerant IT93K503-1 and drought susceptible CB46 genotypes was digested with combinations of EcoR1 and HpaII, Mse1, or Msp1 restriction enzymes and amplified with primers designed from 13 drought-responsive cDNAs. JoinMap 3.0 and MapQTL 4.0 software were used to incorporate polymorphic markers onto the AFLP map and to analyze their association with the drought response QTL. Seven markers co-located with peaks of previously identified QTL. Isolation, sequencing, and blast analysis of these markers confirmed their significant homology with drought or other abiotic stress-induced expressed sequence tags (EST) from cowpea and other plant systems. Further, homology with coding sequences for a multidrug resistance protein 3 and a photosystem I assembly protein ycf3 was revealed in two of these candidates. These results provide a platform for the identification and characterization of genetic trait determinants underlying seedling drought tolerance in cowpea
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