3,869 research outputs found

    Spectral Line De-confusion in an Intensity Mapping Survey

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    Spectral line intensity mapping has been proposed as a promising tool to efficiently probe the cosmic reionization and the large-scale structure. Without detecting individual sources, line intensity mapping makes use of all available photons and measures the integrated light in the source confusion limit, to efficiently map the three-dimensional matter distribution on large scales as traced by a given emission line. One particular challenge is the separation of desired signals from astrophysical continuum foregrounds and line interlopers. Here we present a technique to extract large-scale structure information traced by emission lines from different redshifts, embedded in a three-dimensional intensity mapping data cube. The line redshifts are distinguished by the anisotropic shape of the power spectra when projected onto a common coordinate frame. We consider the case where high-redshift [CII] lines are confused with multiple low-redshift CO rotational lines. We present a semi-analytic model for [CII] and CO line estimates based on the cosmic infrared background measurements, and show that with a modest instrumental noise level and survey geometry, the large-scale [CII] and CO power spectrum amplitudes can be successfully extracted from a confusion-limited data set, without external information. We discuss the implications and limits of this technique for possible line intensity mapping experiments.Comment: 13 pages, 14 figures, accepted by Ap

    The clathrin-binding motif and the J-domain of Drosophila Auxilin are essential for facilitating Notch ligand endocytosis

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    <p>Abstract</p> <p>Background</p> <p>Ligand endocytosis plays a critical role in regulating the activity of the Notch pathway. The <it>Drosophila </it>homolog of auxilin (<it>dAux</it>), a J-domain-containing protein best known for its role in the disassembly of clathrin coats from clathrin-coated vesicles, has recently been implicated in Notch signaling, although its exact mechanism remains poorly understood.</p> <p>Results</p> <p>To understand the role of auxilin in Notch ligand endocytosis, we have analyzed several point mutations affecting specific domains of dAux. In agreement with previous work, analysis using these stronger <it>dAux </it>alleles shows that dAux is required for several Notch-dependent processes, and its function during Notch signaling is required in the signaling cells. In support of the genetic evidences, the level of Delta appears elevated in <it>dAux </it>deficient cells, suggesting that the endocytosis of Notch ligand is disrupted. Deletion analysis shows that the clathrin-binding motif and the J-domain, when over-expressed, are sufficient for rescuing <it>dAux </it>phenotypes, implying that the recruitment of Hsc70 to clathrin is a critical role for dAux. However, surface labeling experiment shows that, in <it>dAux </it>mutant cells, Delta accumulates at the cell surface. In <it>dAux </it>mutant cells, clathrin appears to form large aggregates, although Delta is not enriched in these aberrant clathrin-positive structures.</p> <p>Conclusion</p> <p>Our data suggest that <it>dAux </it>mutations inhibit Notch ligand internalization at an early step during clathrin-mediated endocytosis, before the disassembly of clathrin-coated vesicles. Further, the inhibition of ligand endocytosis in <it>dAux </it>mutant cells possibly occurs due to depletion of cytosolic pools of clathrin via the formation of clathrin aggregates. Together, our observations argue that ligand endocytosis is critical for Notch signaling and auxilin participates in Notch signaling by facilitating ligand internalization.</p

    HOW TO OVERCOME ANALPHABETISM IN READING CHINESE CHARACTER

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    Most languages in the world use some system of alphabetical characters: Latin, Greek, Cyrillic, Hebrew, Arabic, Hindi and so on. A foreigner that does not know the language can get some information from a written text provided he knows the alphabet and disposes of a dictionary. When there is no longer an alphabet, but only pictorial characters, the problem becomes at first unsolvable. Chinese is the main language where an ignorant foreigner is completely analphabet. Fortunately there are methods that after some training allow the recognition of pictorial characters. In our university some twenty pupils of the Excellence School participated to an experiment of Chinese alphabetization gluing a traditional practical Chinese first course with information theory methods for dealing with image data bases. In this article first we discuss both the theoretical foundations. Then we give a report of the merging of the two conceptual schemes as it was performed at the excellence school. Finally we draw some conclusions about improvements of the method

    An efficient surrogate model for emulation and physics extraction of large eddy simulations

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    In the quest for advanced propulsion and power-generation systems, high-fidelity simulations are too computationally expensive to survey the desired design space, and a new design methodology is needed that combines engineering physics, computer simulations and statistical modeling. In this paper, we propose a new surrogate model that provides efficient prediction and uncertainty quantification of turbulent flows in swirl injectors with varying geometries, devices commonly used in many engineering applications. The novelty of the proposed method lies in the incorporation of known physical properties of the fluid flow as {simplifying assumptions} for the statistical model. In view of the massive simulation data at hand, which is on the order of hundreds of gigabytes, these assumptions allow for accurate flow predictions in around an hour of computation time. To contrast, existing flow emulators which forgo such simplications may require more computation time for training and prediction than is needed for conducting the simulation itself. Moreover, by accounting for coupling mechanisms between flow variables, the proposed model can jointly reduce prediction uncertainty and extract useful flow physics, which can then be used to guide further investigations.Comment: Submitted to JASA A&C

    STRUCTURES AND PATHS FOR THE EXPLORATION OF LANDSCAPE – CULTURAL MOSAIC

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    The main aim of this paper is to highlight the evolution of urban and peri-urban networks in view of their use by dwellers and visitors. It considers the knowledge as a part of a hidden permanent education form, and as a prerequisite for full enjoyment of available culture, sport and health facilities. Although, the objectives of the inhabitants and tourists are very different, their basic structural needs and the underlying methodology have common characteristics. In this prospective, the central element is the ability to build networks that connect the nodes of interest, which are functional (services at various levels), cultural (historical and artistic emerging features), and leisure (dedicated sport facilities and locations). Furthermore, the paper investigates the paths and times of networks connections, providing particular attention to multipurpose trips consistence of either dwellers or tourists
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