6,551 research outputs found

    The Wide Field Imaging Interferometry Testbed

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    We are developing a Wide-Field Imaging Interferometry Testbed (WIIT) in support of design studies for NASA's future space interferometry missions, in particular the SPIRIT and SPECS far-infrared/submillimeter interferometers. WIIT operates at optical wavelengths and uses Michelson beam combination to achieve both wide-field imaging and high-resolution spectroscopy. It will be used chiefly to test the feasibility of using a large-format detector array at the image plane of the sky to obtain wide-field interferometry images through mosaicing techniques. In this setup each detector pixel records interferograms corresponding to averaging a particular pointing range on the sky as the optical path length is scanned and as the baseline separation and orientation is varied. The final image is constructed through spatial and spectral Fourier transforms of the recorded interferograms for each pixel, followed by a mosaic/joint-deconvolution procedure of all the pixels. In this manner the image within the pointing range of each detector pixel is further resolved to an angular resolution corresponding to the maximum baseline separation for fringe measurements. We present the motivation for building the testbed, show the optical, mechanical, control, and data system design, and describe the image processing requirements and algorithms. WIIT is presently under construction at NASA's Goddard Space Flight Center.Comment: 7 pages, 3 figures, IEEE Aerospace Conference 200

    Safeguarding IoMT: Semi-automated Intrusion Detection System (SAIDS) for detecting multilayer attacks

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    The Internet of Medical Things (IoMT) plays a significant role in the healthcare system as it improves effectiveness and efficiency of treatment by continuously monitoring patients using smart home sensor and wearables (Fig. 1). IoMT devices are vulnerable to Multi-layer attacks that are exploiting multiple layers of IoMT architecture (Fig. 2). Denial-of-service (DoS) and Man-In-The-Middle (MITM) attacks, for instance, can target the three layers of the IoMT system and lead to serious consequences, such as theft of patients’ sensitive data and reputational damages [2]. This project aims to create a robust detection system for multilayer attacks using a Semi-automated Intrusion Detection System (SAIDS) for IoT devices. To achieve this aim, we have focused on the following objectives: • Explore a variety of feature selection algorithms. • Apply feature weighting. • Integrating human and machine learning approaches to work together. • Increase detection efficiency by utilizing significant features

    Investigating the security issues of multi-layer IoMT attacks using machine learning techniques

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    The Internet of Medical Things (IoMT) plays a significant role in the healthcare system as it improves effectiveness and efficiency of treatment by continuously monitoring patients using smart home sensor and wearables (Fig. 1), early disease diagnosis using data collected from the Internet of Medical Things (IoMT) devices and assisting doctors in deciding the best treatment and acting immediately if necessary. Additionally, it helps to reduce the number of hospital visits, limiting carbon footprint.IoMT devices are vulnerable to Multi-layer attacks because most of these devices are resource-constrained and portable, which is why there is not that much implementation of security features in these devices and making them a prime target for intruders looking to steal patients’ sensitive information and healthcare records. Multi-layer attacks are a group of attacksexploiting multiple layers of IoMT architecture. Denial-of-service (DoS) and Man-In-The-Middle (MITM) attacks, for instance, can target the three layers of the IoMT system and lead to serious consequences, such as theft of patients’ sensitive data and reputational damages. The main aim of the project is to create a robust IDS for IoT devices

    Glucosamine HCl-based solid dispersions to enhance the biopharmaceutical properties of acyclovir

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    The objective of the work presented here was to assess the feasibility of using glucosamine HCl as a solid-dispersion (SD) carrier to enhance the biopharmaceutical properties of a BCS class III/IV drug, acyclovir (ACV). The solid-dispersions of acyclovir and glucosamine HCl were prepared by an ethanol-based solvent evaporation method. The prepared formulations characterized by photomicroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transforms infrared spectrophotometry (FTIR), powder x-ray diffractometry (PXRD) and drug content analysis. The functional characterization of ACV-SD was performed by aqueous solubility evaluation, dissolution studies, fasted versus fed state dissolution comparison, ex vivo permeability, and stability studies. Photomicroscopy and SEM analysis showed different surface morphologies for pure ACV, glucosamine HCl and ACV-SD. The physical-chemical characterization studies supported the formation of ACV-SD. A 12-fold enhancement in the aqueous solubility of ACV was observed in the prepared solid dispersions, compared to pure ACV. Results from in vitro dissolution demonstrated a significant increase in the rate and extent of ACV dissolution from the prepared ACV-SD formulations, compared to pure ACV. The rate and extent of ACV permeability across everted rat intestinal membrane were also found to be significantly increased in the ACV-SD formulations. Under fed conditions, the rate and extent of the in vitro dissolution of ACV from the formulation was appreciably greater compared to fasted conditions. Overall, the results from the study suggest the feasibility of utilizing glucosamine HCl as a solid dispersion carrier/excipient for enhancement of biopharmaceutical properties of acyclovir, and similar drugs with low solubility/permeability characteristics

    LABA/LAMA combinations versus LAMA monotherapy or LABA/ICS in COPD : a systematic review and meta-analysis

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    Acknowledgments The meta-analysis work was performed by Guruprasad Rao KS and Sharanbasappa Durg of Molecular Connections (P) Ltd, Bangalore, India, under the guidance of the manuscript authors and Novartis Pharma AG (Basel, Switzerland). Medical writing assistance was provided by Colette O’Sullivan, PhD, of Scriva Medical Communications Ltd, a professional medical writer funded by Novartis. Development of the manuscript was supported by Novartis Pharma AG (Basel, Switzerland). The authors received no compensation related to the development of the manuscript.Peer reviewedPublisher PD

    A review and evaluation of secondary school accountability in England: Statistical strengths, weaknesses, and challenges for 'Progress 8' raised by Covid-19

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    School performance measures are published annually in England to hold schools to account and to support parental school choice. This article reviews and evaluates the ‘Progress 8’ secondary school accountability system for state-funded schools. We assess the statistical strengths and weaknesses of Progress 8 relating to: choice of pupil outcome attainment measure; potential adjustments for pupil input attainment and background characteristics; decisions around which schools and pupils are excluded from the measure; presentation of Progress 8 to users, choice of statistical model, and calculation of statistical uncertainty; and issues related to the volatility of school performance over time, including scope for reporting multi-year averages. We then discuss challenges for Progress 8 raised by the COVID-19 pandemic. Six simple recommendations follow to improve Progress 8 and school accountability in England. Context and implication Rationale for this study This study fulfils a need for a comprehensive statistical evaluation of the Progress 8 school accountability system in England, which has been in place since 2016. Why the new findings matter A review of Progress 8 is an important contribution as decisions on its calculation and presentation have important consequences for schools and pupils. Implications for educational researchers and policy makers Our findings on the statistical strengths and weaknesses of Progress 8 and the resulting recommendations made for improvements to the measure and school accountability have clear implications for informing policy makers in the educational system. This includes wider lessons extending beyond Progress 8 to other performance metrics and to other school systems internationally where similar issues apply. Additionally, the review highlights key concerns that the public and school practitioners may like to consider when drawing upon Progress 8 to make decisions around school choice and in assessing how well a school is performing

    Design of a Supervisory Control System for Autonomous Operation of Advanced Reactors

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    Advanced reactors to be deployed in the coming decades will face deregulated energy markets, and may adopt flexible operation to boost profitability. To aid in the transition from baseload to flexible operation paradigm, autonomous operation is sought. This work focuses on the control aspect of autonomous operation. Specifically, a hierarchical control system is designed to support constraint enforcement during routine operational transients. Within the system, data-driven modeling, physics-based state observation, and classical control algorithms are integrated to provide an adaptable and robust solution. A 320 MW Fluoride-cooled High-temperature Pebble-bed Reactor is the design basis for demonstrating the control system. The hierarchical control system consists of a supervisory layer and low-level layer. The supervisory layer receives requests to change the system's operating conditions, and accepts or rejects them based on constraints that have been assigned. Constraints are issued to keep the plant within an optimal operating region. The low-level layer interfaces with the actuators of the system to fulfill requested changes, while maintaining tracking and regulation duties. To accept requests at the supervisory layer, the Reference Governor algorithm was adopted. To model the dynamics of the reactor, a system identification algorithm, Dynamic Mode Decomposition, was utilized. To estimate the evolution of process variables that cannot be directly measured, the Unscented Kalman Filter, incorporating a nonlinear model of nuclear dynamics, was adopted. The composition of these algorithms led to a numerical demonstration of constraint enforcement during a 40 % power drop transient. Adaptability was demonstrated by modifying the constraint values, and enforcing them during the transient. Robustness was demonstrated by enforcing constraints under noisy environments.Comment: 19 pages, 12 figure

    A comparison of the galaxy populations in the Coma and distant clusters: the evolution of k+a galaxies and the role of the intracluster medium

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    The spectroscopic properties of galaxies in the Coma cluster are compared with those of galaxies in rich clusters at z0.5z \sim 0.5, to investigate the evolution of the star formation history in clusters. Luminous galaxies with MV20M_V \leq -20 and post-starburst/post-starforming (k+a) spectra which constitute a significant fraction of galaxies in distant cluster samples are absent in Coma, where spectacular cases of k+a spectra are found instead at MV>18.5M_V>-18.5 and represent a significant proportion of the cluster dwarf galaxy population. A simple inspection of their positions on the sky indicates that this type of galaxy does not show a preferential location within the cluster, but the bluest and strongest-lined group of k+a's lies in projection towards the central 1.4 Mpc of Coma and have radial velocities significantly higher than the cluster mean. We find a striking correlation between the positions of these young and strong post-starburst galaxies and substructure in the hot intracluster medium (ICM) identified from {\it XMM-Newton} data, with these galaxies lying close to the edges of two infalling substructures. This result strongly suggests that the interaction with the dense ICM could be responsible for the quenching of the star formation (thus creating the k+a spectrum), and possibly, for any previous starburst. The evolution with redshift of the luminosity distribution of k+a galaxies can be explained by a ``downsizing effect'', with the maximum luminosity/mass of actively star-forming galaxies infalling onto clusters decreasing at lower redshift. We discuss the possible physical origin of this downsizing effect and the implications of our results for current scenarios of environmental effects on the star formation in galaxies.Comment: 21 pages, 7 figures, to appear in ApJ, version after referee's change
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