4,134 research outputs found

    Approximate Inference for Constructing Astronomical Catalogs from Images

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    We present a new, fully generative model for constructing astronomical catalogs from optical telescope image sets. Each pixel intensity is treated as a random variable with parameters that depend on the latent properties of stars and galaxies. These latent properties are themselves modeled as random. We compare two procedures for posterior inference. One procedure is based on Markov chain Monte Carlo (MCMC) while the other is based on variational inference (VI). The MCMC procedure excels at quantifying uncertainty, while the VI procedure is 1000 times faster. On a supercomputer, the VI procedure efficiently uses 665,000 CPU cores to construct an astronomical catalog from 50 terabytes of images in 14.6 minutes, demonstrating the scaling characteristics necessary to construct catalogs for upcoming astronomical surveys.Comment: accepted to the Annals of Applied Statistic

    Hyaluronan Modulated Expression of MMPs 2, 9, and 12 in Macrophages

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    Hyaluronan (HA) is a ubiquitously expressed Glycosaminoglycan (GAG) found as a main component of the extracellular matrix (ECM). Matrix metalloproteases (MMPs) are class of enzyme responsible for the degradation of multiple ECM components, including HA. Following a myocardial infarction (MI), ECM remodeling occurs in the infarct tissue and involves an accumulation of HA. Remodeling is facilitated by multiple cell types, including macrophages. During post-MI ECM remodeling, macrophages degrade and ingulf dead cells and ECM components, a process which requires the expression of MMPs. MMPs 2, 9, and 12 are known to be elevated post-MI; MMPs 9 and 12 are known to have HA as a substrate. These factors make MMPs 2, 9, and 12 especially relevant to the post-MI ECM remodeling process. The effect of increased HA present post-MI on levels of MMP expression in macrophages has yet to be investigated

    Use of an Integrated Pest Management Assessment Administered Through TurningPoint as an Educational, Needs Assessment, and Evaluation Tool

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    University of Minnesota educators use an integrated pest management (IPM) survey conducted during private pesticide applicator training as an educational, needs assessment, and evaluation tool. By incorporating the IPM Assessment, as the survey is called, into a widely attended program and using TurningPoint audience response devices, Extension educators can gather information from a significant number of farmers in a timely and efficient manner. Interspersing TurningPoint questions throughout presentations also increases audience engagement and overall quality of the training. For example, weed management programming efforts around herbicide-resistance management have been significantly influenced and enhanced by results of the IPM Assessment

    Real-time crowd control of existing interfaces

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    Crowdsourcing has been shown to be an effective approach for solving difficult problems, but current crowdsourcing systems suffer two main limitations: (i) tasks must be repackaged for proper display to crowd workers, which generally requires substantial one-off programming effort and support infrastructure, and (ii) crowd workers generally lack a tight feedback loop with their task. In this paper, we introduce Legion, a system that allows end users to easily capture existing GUIs and outsource them for collaborative, real-time control by the crowd. We present mediation strategies for integrating the input of multiple crowd workers in real-time, evaluate these mediation strategies across several applications, and further validate Legion by exploring the space of novel applications that it enables

    VizWiz

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    The lack of access to visual information like text labels, icons,and colors can cause frustration and decrease independence for blind people. Current access technology uses automatic approaches to address some problems in this space, but the technology is error-prone, limited in scope, and quite expensive. In this paper, we introduce VizWiz, a talking application for mobile phones that offers a new alternative to answering visual questions in nearly real-time—asking multiple people on the web. To support answering questions quickly, we introduce a general approach for intelligently recruiting human workers in advance called quikTurkit so that workers are available when new questions arrive. A field deployment with 11 blind participants illustrates that blind people can effectively use VizWiz to cheaply answer questions in their everyday lives, highlighting issues that automatic approaches will need to address to be useful. Finally, we illustrate the potential of using VizWiz as part of the participatory design of advanced tools by using it to build and evaluate VizWiz::LocateIt, an interactive mobile tool that helps blind people solve general visual search problems

    N17 Modifies mutant Huntingtin nuclear pathogenesis and severity of disease in HD BAC transgenic mice.

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    The nucleus is a critical subcellular compartment for the pathogenesis of polyglutamine disorders, including Huntington's disease (HD). Recent studies suggest the first 17-amino-acid domain (N17) of mutant huntingtin (mHTT) mediates its nuclear exclusion in cultured cells. Here, we test whether N17 could be a molecular determinant of nuclear mHTT pathogenesis in vivo. BAC transgenic mice expressing mHTT lacking the N17 domain (BACHD-ΔN17) show dramatically accelerated mHTT pathology exclusively in the nucleus, which is associated with HD-like transcriptionopathy. Interestingly, BACHD-ΔN17 mice manifest more overt disease-like phenotypes than the original BACHD mice, including body weight loss, movement deficits, robust striatal neuron loss, and neuroinflammation. Mechanistically, N17 is necessary for nuclear exclusion of small mHTT fragments that are part of nuclear pathology in HD. Together, our study suggests that N17 modifies nuclear pathogenesis and disease severity in HD mice by regulating subcellular localization of known nuclear pathogenic mHTT species

    Adsorbate-induced structural changes in 1-3 nm platinum nanoparticles

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    We investigated changes in the Pt–Pt bond distance, particle size, crystallinity, and coordination of Pt nanoparticles as a function of particle size (1–3 nm) and adsorbate (H2, CO) using synchrotron radiation pair distribution function (PDF) and X-ray absorption spectroscopy (XAS) measurements. The ∼1 nm Pt nanoparticles showed a Pt–Pt bond distance contraction of ∼1.4%. The adsorption of H2 and CO at room temperature relaxed the Pt–Pt bond distance contraction to a value close to that of bulk fcc Pt. The adsorption of H2 improved the crystallinity of the small Pt nanoparticles. However, CO adsorption generated a more disordered fcc structure for the 1–3 nm Pt nanoparticles compared to the H2 adsorption Pt nanoparticles. In situ XANES measurements revealed that this disorder results from the electron back-donation of the Pt nanoparticles to CO, leading to a higher degree of rehybridization of the metal orbitals in the Pt-adsorbate system
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