3,195 research outputs found

    The Formin FMNL3 Controls Early Apical Specification in Endothelial Cells by Regulating the Polarized Trafficking of Podocalyxin

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    SummaryAngiogenesis is the fundamental process by which new blood vessels form from pre-existing vasculature. It plays a critical role in the formation of the vasculature during development and is triggered in response to tissue hypoxia in adult organisms. This process requires complex and coordinated regulation of the endothelial cell cytoskeleton to control cell shape and polarity. In our previous work, we showed that the cytoskeletal regulator FMNL3/FRL2 controls the alignment of stabilized microtubules during polarized endothelial cell elongation and that depletion of FMNL3 retards elongation of the intersegmental vessels in zebrafish [1]. Recent work has shown that FMNL3 is also needed for vascular lumen formation [2], a critical element of the formation of functional vessels. Here, we show that FMNL3 interacts with Cdc42 and RhoJ, two Rho family GTPases known to be required for lumen formation. FMNL3 and RhoJ are concentrated at the early apical surface, or AMIS, and regulate the formation of radiating actin cables from this site. In diverse biological systems, formins mediate polarized trafficking through the generation of similar actin filaments tracks. We show that FMNL3 and RhoJ are required for polarized trafficking of podocalyxin to the early apical surface—an important event in vascular lumenogenesis

    A Framework for Intranet-Based Information Systems (I-BIS) Applications

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    A recent survey of business executives showed that of 169 decision makers who responded to a survey by the Business Research Group, over fifty percent have either already implemented an internal web site or are in the process of developing such a site (Engler, 1996). These results were similar to those reported in InformationWeek, which showed that 49% of those firms responding to the survey already had direct Internet access for their employees. According to this same survey, this figure is expected to increase to 67% of these same firms by the spring of 1997 with another 10% of the firms testing the viability of such a connectivity policy (Yankelovich, 1996). Gantz (1986) reported that the microcomputer had achieved the same level of penetration into the corporate world (in terms of the percentage of employees with desktop access) in ten years that the telephone required 75 years to achieve. With these systems increasingly tied together in local or wide area networks, it is likely that a comparable level of penetration of Intranet-Based Information System (I-BIS) will occur in an even shorter time span. The rapid proliferation of network communication technology points to a need to measure how and where these systems are being implemented, and what results are being achieved. Recently published reports concerning Intranet-Based Information Systems (I-BIS) have cited return on investment values exceeding 1300% and direct payback time periods of six to twelve weeks (Campbell, 1996). While these systems have already been widely accepted and implemented, scant attention has been paid to rigorous research in relation to users\u27 acceptance and utilization of these systems or the perceived quality of these system

    A cloned linguistic decision tree controller for real-time path planning in hostile environments

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    AbstractThe idea of a Cloned Controller to approximate optimised control algorithms in a real-time environment is introduced. A Cloned Controller is demonstrated using Linguistic Decision Trees (LDTs) to clone a Model Predictive Controller (MPC) based on Mixed Integer Linear Programming (MILP) for Unmanned Aerial Vehicle (UAV) path planning through a hostile environment. Modifications to the LDT algorithm are proposed to account for attributes with circular domains, such as bearings, and discontinuous output functions. The cloned controller is shown to produce near optimal paths whilst significantly reducing the decision period. Further investigation shows that the cloned controller generalises to the multi-obstacle case although this can lead to situations far outside of the training dataset and consequently result in decisions with a high level of uncertainty. A modification to the algorithm to improve the performance in regions of high uncertainty is proposed and shown to further enhance generalisation. The resulting controller combines the high performance of MPC–MILP with the rapid response of an LDT while providing a degree of transparency/interpretability of the decision making

    Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry

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    We identify 885,503 type 1 quasar candidates to i<22 using the combination of optical and mid-IR photometry. Optical photometry is taken from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from the Wide-Field Infrared Survey Explorer (WISE) "ALLWISE" data release and several large-area Spitzer Space Telescope fields. Selection is based on a Bayesian kernel density algorithm with a training sample of 157,701 spectroscopically-confirmed type-1 quasars with both optical and mid-IR data. Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623 are objects that we have not previously classified as photometric quasar candidates). These candidates include 7874 objects targeted as high probability potential quasars with 3.5<z<5 (of which 6779 are new photometric candidates). Our algorithm is more complete to z>3.5 than the traditional mid-IR selection "wedges" and to 2.2<z<3.5 quasars than the SDSS-III/BOSS project. Number counts and luminosity function analysis suggests that the resulting catalog is relatively complete to known quasars and is identifying new high-z quasars at z>3. This catalog paves the way for luminosity-dependent clustering investigations of large numbers of faint, high-redshift quasars and for further machine learning quasar selection using Spitzer and WISE data combined with other large-area optical imaging surveys.Comment: 54 pages, 17 figures; accepted by ApJS Data for tables 1 and 2 available at http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/master_quasar_catalogs.011414.fits.bz2 and http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/optical_ir_quasar_candidates.052015.fits.bz

    A Flexible Spatio-Temporal Model for Air Pollution: Allowing for Spatio-Temporal Covariates

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    Given the increasing interest in the association between exposure to air pollution and adverse health outcomes, the development of models that provide accurate spatio-temporal predictions of air pollution concentrations at small spatial scales is of great importance when assessing potential health effects of air pollution. The methodology presented here has been developed as part of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), a prospective cohort study funded by the US EPA to investigate the relationship between chronic exposure to air pollution and cardiovascular disease. We present a spatio-temporal framework that models and predicts ambient air pollution by combining data from several different monitoring networks with the output from deterministic air pollution model(s). The model can accommodate arbitrarily missing observations and allows for a complex spatio-temporal correlation structure. We apply the model to predict long-term average concentrations of gaseous oxides of nitrogen (NOx) ─ one of the primary pollutants of interest in the MESA Air study ─ during a ten year period in the Los Angeles area, based on measurements from the EPA Air Quality System and MESA Air monitoring. The measurements are augmented by a spatio-temporal covariate based on the output from a source dispersion model for traffic related air pollution (Caline3QHC) and the model is evaluated using cross-validation. The predictive ability of the model is good with cross-validated R2 of approximately 0.7 at subject sites. The incorporation of a dispersion model output into the overall prediction model was feasible, but the particular implementation of Caline3QHC used here did not improve predictions in a model that also includes road information. However, excluding the road information the inclusion of model output improves predictions and we find some evidence that the source dispersion model can replace road covariates. The model presented in this paper has been implemented in an R package, SpatioTemporal, which will be available on CRAN shortly

    Eight-Dimensional Mid-Infrared/Optical Bayesian Quasar Selection

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    We explore the multidimensional, multiwavelength selection of quasars from mid-IR (MIR) plus optical data, specifically from Spitzer-IRAC and the Sloan Digital Sky Survey (SDSS). We apply modern statistical techniques to combined Spitzer MIR and SDSS optical data, allowing up to 8-D color selection of quasars. Using a Bayesian selection method, we catalog 5546 quasar candidates to an 8.0 um depth of 56 uJy over an area of ~24 sq. deg; ~70% of these candidates are not identified by applying the same Bayesian algorithm to 4-color SDSS optical data alone. Our selection recovers 97.7% of known type 1 quasars in this area and greatly improves the effectiveness of identifying 3.5<z<5 quasars. Even using only the two shortest wavelength IRAC bandpasses, it is possible to use our Bayesian techniques to select quasars with 97% completeness and as little as 10% contamination. This sample has a photometric redshift accuracy of 93.6% (Delta Z +/-0.3), remaining roughly constant when the two reddest MIR bands are excluded. While our methods are designed to find type 1 (unobscured) quasars, as many as 1200 of the objects are type 2 (obscured) quasar candidates. Coupling deep optical imaging data with deep mid-IR data could enable selection of quasars in significant numbers past the peak of the quasar luminosity function (QLF) to at least z~4. Such a sample would constrain the shape of the QLF and enable quasar clustering studies over the largest range of redshift and luminosity to date, yielding significant gains in our understanding of quasars and the evolution of galaxies.Comment: 49 pages, 14 figures, 7 tables. AJ, accepte

    Scholarship in Review 89(1)

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    Scholarship in Review was a magazine highlighting research and scholarly activities at Central Washington University, published by the Office of Graduate Studies and Research.https://digitalcommons.cwu.edu/scholarship_in_review/1005/thumbnail.jp

    Modular video endoscopy for in vivo cross-polarized and vital-dye fluorescence imaging of Barrett's-associated neoplasia

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    A modular video endoscope is developed and tested to allow imaging in different modalities. This system incorporates white light imaging (WLI), cross-polarized imaging (CPI), and vital-dye fluorescence imaging (VFI), using interchangeable filter modules. CPI and VFI are novel endoscopic modalities that probe mucosal features associated with Barrett's neoplasia. CPI enhances vasculature, while VFI enhances glandular architecture. In this pilot study, we demonstrate the integration of these modalities by imaging areas of Barrett's metaplasia and neoplasia in an esophagectomy specimen. We verify that those key image features are also observed during an in vivo surveillance procedure. CPI images demonstrate improved visualization of branching blood vessels associated with neoplasia. VFI images show glandular architecture with increased glandular effacement associated with neoplasia. Results suggests that important pathologic features seen in CPI and VFI are not visible during standard endoscopic white light imaging, and thus the modalities may be useful in future in vivo studies for discriminating neoplasia from Barrett's metaplasia. We further demonstrate that the integrated WLI/CPI/VFI endoscope is compatible with complementary high-resolution endomicroscopy techniques such as the high-resolution microendoscope, potentially enabling two-step (“red-flag” widefield plus confirmatory high-resolution imaging) protocols to be enhanced
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