7,172 research outputs found

    Experiment K-6-06. Morphometric and EM analyses of tibial epiphyseal plates from Cosmos 1887 rats

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    Light and electron microscopy studies were carried out on decalcified tibial epiphyseal plates of rats flown aboard Cosmos 1887 (12.5d flight plus 53.5h recovery). Analysis of variance showed that the proliferative zone of flight animals was significantly higher than that of synchronous controls, while the hypertrophic/calcification zone was significantly reduced. Flight animals had more cells than synchronous controls in the proliferative zone, and less in the hypertrophic/calcification region. The total number of cells, however, was significantly higher in flight animals. No differences were found for perimeter or shape factor of growth plates, but area was significantly lower in flight animals in comparison to synchronous controls. Collagen fibrils in flight animals were shorter and wider than in synchronous controls. The time required for a cell to cycle through the growth plate is 2 to 3 days, so most of the cells and matrix present were formed after the animals had returned to 1 g, and probably represent stages of recovery from microgravity exposure, which in itself is an interesting question

    Synchronization of the Frenet-Serret linear system with a chaotic nonlinear system by feedback of states

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    A synchronization procedure of the generalized type in the sense of Rulkov et al [Phys. Rev. E 51, 980 (1995)] is used to impose a nonlinear Malasoma chaotic motion on the Frenet-Serret system of vectors in the differential geometry of space curves. This could have applications to the mesoscopic motion of biological filamentsComment: 12 pages, 7 figures, accepted at Int. J. Theor. Phy

    Availability of Microtrash Materials and Selectivity by California Condors

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    California condors consume non-food items, including anthropogenic waste, and provision it to their young. Consuming “microtrash” can cause mortality, especially in nestlings. There are several hypotheses explaining why condors might consume microtrash. These hypotheses assume condors exhibit a preference for the type of material. Therefore, we test the assumption that when California condors take microtrash, they display material selectivity. We did this by sampling microtrash from roadside pullouts in the Los Padres National Forest. Those samples were compared to condor necropsy and nest microtrash data, categorized by material type: glass, plastic, metal, and other. We find that in our analysis condors exhibit a preference for plastics and an avoidance of “other” materials (primarily ceramic)

    Reading Spaces: Nation and Popular Learning in Nineteenth-Century Lima

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    My dissertation examined the transformation of reading practices and ideas about the functions of alphabetic literacy in nineteenth-century Lima. Scholars of Latin America have attributed improvements in literacy rates to the rise of the Teaching State in the twentieth century; however, as I showed, literacy and reading culture spread decades earlier in the Peruvian capital, at a time when the state lacked the stability and resources to develop a public system of education. “Reading Spaces” argued that during the second half of the nineteenth century, private educational enterprise from a diverse group of booksellers, writers, and educators established key institutions of the modern Teaching State, including a national textbook industry as well as pedagogical newspapers, associations, and conferences. They did so in a process that promoted new pedagogical methods and helped spread alphabetic literacy and reading practices. Developments in the disciplines of book history, the cultural history of education, and the history of reading informed my methodological approach to a variety of previously unexamined sources including books, textbooks, pedagogical periodicals, as well as bookstore organ newspapers and catalogues. Both the intellectual content and paratext of published sources provided a wealth of information regarding the circulation of the texts, their reception among state authorities and influential members of Lima’s society, and the relationship of book and textbook authors to their publishers and readers. My dissertation revealed that textbook standardization and the proliferation of pedagogical newspapers were processes firmly rooted in the development of Peru’s private educational enterprise, publishing industry and educational legislation of the nineteenth century. These processes expanded Lima’s public sphere, where booksellers, editors, writers, and teachers debated modern pedagogies and promoted broad engagement in educational matters. They conducted pedagogical conferences, intellectual competitions, national expositions and reorganized civic festivities. The presence of a pedagogical public sphere, which directed the course of institutions of the modern nation state in Peru, encourages a reassessment of our traditional narratives of the relationship between education and nation in Latin America and beyond

    Tunable entanglement distillation of spatially correlated down-converted photons

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    We report on a new technique for entanglement distillation of the bipartite continuous variable state of spatially correlated photons generated in the spontaneous parametric down-conversion process (SPDC), where tunable non-Gaussian operations are implemented and the post-processed entanglement is certified in real-time using a single-photon sensitive electron multiplying CCD (EMCCD) camera. The local operations are performed using non-Gaussian filters modulated into a programmable spatial light modulator and, by using the EMCCD camera for actively recording the probability distributions of the twin-photons, one has fine control of the Schmidt number of the distilled state. We show that even simple non-Gaussian filters can be finely tuned to a ~67% net gain of the initial entanglement generated in the SPDC process.Comment: 12 pages, 6 figure

    Iterative Information Granulation for Novelty Detection in Complex Datasets

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    Recognition memory in a number of mammals is usually utilised to identify novel objects that violate model predictions. In humans in particular, the recognition of novel objects is foremost associated to their ability to group objects that are highly compatible/similar. Granular computing not only mimics the human cognition to draw objects together but also mimics the ability to capture associated properties by similarity, proximity or functionality. In this paper, an iterative information granulation approach is presented, for the problem of novelty detection in complex data. Two granular compatibility measures are used, based on principles of Granular Computing, namely the multidimensional distance between the granules, as well as the granular density and volume. A two-stage iterative information granulation is proposed in this work. In the first stage, a predefined number of granular detectors are constructed. The granular detectors capture the relationships (rules) between the input-output data and then use this information in a second granulation stage in order to discriminate new samples as novel. The proposed iterative information granulation approach for novelty detection is then applied to three different benchmark problems in pattern recognition demonstrating very good performance

    An ensemble data-driven fuzzy network for laser welding quality prediction

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    This paper presents an Ensemble Data-Driven Fuzzy Network (EDDFN) for laser welding quality prediction that is composed of a number of strategically selected Data-Driven Fuzzy Models (DDFMs). Each model is trained by an Adaptive Negative Correlation Learning approach (ANCL). A monitoring system provides quality-relevant information of the laser beam spectrum and the geometry of the melt pool. This information is used by the proposed ensemble model to asist in the prediction of the welding quality. Each DDFM is based on three conceptual components, i.e. a selection procedure of the most representative welding information, a granular comprehesion process of data and the construction of a fuzzy reasoning mechanism as a series of Radial Basis Function Neural Networks (RBF-NNs). The proposed model aims at providing a fuzzy reasoning engine that is able to preserve a good balance between transparency and accuracy while improving its prediction properties. We apply the EDDFN to a real case study in manufacturing industry for the prediction of welding quality. The corresponding results confirm that the EDDFN provides better prediction properties compared to a single DDFM with an overal prediction performance > 78%

    Ion condensation on charged patterned surfaces

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    We study ion condensation onto a patterned surface of alternating charges. The competition between self-energy and ion-surface interactions leads to the formation of ionic crystalline structures at low temperatures. We consider different arrangements of underlying ionic crystals, including single ion adsorption, as well as the formation of dipoles at the interface between charged domains. Molecular dynamic simulation illustrates existence of single and mixed phases. Our results contribute to understanding pattern recognition, and molecular separation and synthesis near patterned surfaces.Comment: 3 figure
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