239 research outputs found

    A Conceptual Model of an Information Security Domain Knowledge Base

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    Information Security breaches and threats continue to grow worldwide. Securing information systems issues persist despite the development of several Information security standards. The low adoption rate of these security standards is one of the main contributing factors for this growing problem. As emerging economies seek to be a part of the digital economy it is prudent that they make information security a priority. The lack of effective Information Security Strategies in developing countries has resulted in these countries facing the problem of becoming targets for cyber criminals. In this research we present a Conceptual Model and a design of an Information Security Domain Knowledge Base (InfoSec DKB) that can assist in developing and managing information security strategies. This design is based on a combination of decision making, security and auditing frameworks, namely concepts of the Value Focused Thinking (VFT) approach used in decision making, the Guidelines for Management of IT security (ISO/IEC 27001), Control Objectives for Information and Related Technologies (COBIT)

    Is there a Consensus in the Management of Distal Radial Fractures?

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    This unique postal survey was setup to assess the agreement on treatment options in displaced distal radius fractures and whether or not there existed a consensus amongst the surgeons contacted. With this in view we contacted 244 surgeons and 166 completed answers were received

    NMMA: A nuclear-physics and multi-messenger astrophysics framework to analyze binary neutron star mergers

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    The multi-messenger detection of the gravitational-wave signal GW170817, the corresponding kilonova AT2017gfo and the short gamma-ray burst GRB170817A, as well as the observed afterglow has delivered a scientific breakthrough. For an accurate interpretation of all these different messengers, one requires robust theoretical models that describe the emitted gravitational-wave, the electromagnetic emission, and dense matter reliably. In addition, one needs efficient and accurate computational tools to ensure a correct cross-correlation between the models and the observational data. For this purpose, we have developed the NMMA (Nuclear-physics and Multi-Messenger Astrophysics) framework. The code allows incorporation of nuclear-physics constraints at low densities as well as X-ray and radio observations of isolated neutron stars. It also enables us to classify electromagnetic observations, e.g., to distinguish between supernovae and kilonovae. In previous works, the NMMA code has allowed us to constrain the equation of state of supranuclear dense matter, to measure the Hubble constant, and to compare dense-matter physics probed in neutron-star mergers and in heavy-ion collisions. The extension of the NMMA code presented here is the first attempt of analysing the gravitational-wave signal, the kilonovae, and the GRB afterglow simultaneously, which reduces the uncertainty of our constraints. Incorporating all available information, we estimate the radius of a 1.4 solar mass neutron star to be R=11.980.40+0.35R=11.98^{+0.35}_{-0.40} km

    Effect of fiber stacking sequence and orientation on quasi- static indentation properties of sustainable hybrid carbon/ramie fiber epoxy composites

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    Hybrid polymer composites reinforced with synthetic and natural fibers are gaining more interest in current composite technology in an effort to promote sustainability without sacrificing the performance of synthetic fiber reinforced polymer composites. The goal of this study is to see how the fiber stacking sequence of carbon and ramie fiber, as well as the orientation of ramie fiber, affects the quasi-static indentation behaviour of carbon/ramie fiber reinforced epoxy hybrid composites. The hybrid composite specimens were made using a hand layup approach followed by a hot pressing process. The quasi-static indentation properties of carbon/ramie fiber reinforcements in epoxy matrix were investigated using a hemispherical indenter at varying indenter displacement rates of 10, 20, and 30 ​mm/min for the stated stacking sequence and orientation. The indentation resistance qualities of carbon/ramie fiber reinforced epoxy hybrid composites were evaluated in terms of indentation force, hybrid composite specimen energy absorption capability, and hybrid composite specimen damage caused by hemispherical indenter penetration. The results reveal that a carbon/ramie fiber reinforced epoxy hybrid composite with 5 ramie fiber layers has better energy absorption capabilities, absorbing 114.926 ​J at a 20 ​mm/min indentation rate. Similarly, the indentation force in hybrid composites increases as the number of carbon/ramie fiber layers increases. These results indicate that carbon/ramie fiber reinforced epoxy hybrid composites have a great potential towards low velocity impact applications

    Characterization of Aerosol Deposited Cesium Lead Tribromide Perovskite Films on Interdigited ITO Electrodes

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    Aerosol deposition (AD) is a promising additive manufacturing method to fabricate low-cost, scalable films at room temperature, but has not been considered for semiconductor processing, so far. The successful preparation of cesium lead tribromide (CsPbBr) perovskite films on interdigitated indium tin oxide (ITO) electrodes by means of AD is reported here. The – µm thick layers are dense and have good adhesion to the substrate. The orthorhombic Pnma crystal structure of the precursor powder was retained during the deposition process with no signs of defect formation. The formation of electronic defects by photoluminescence spectroscopy is investigated and found slightly increased carrier recombination from defect sites for AD films compared to the powder. A nonuniform defect distribution across the layer, presumably induced by the impact of the semiconducting grains on the hard substrate surface, is revealed. The opto-electronic properties of AD processed semiconducting films is further tested by electrical measurements and confirmed good semiconducting properties and high responsivity for the films. These results demonstrate that AD processing of metal halide perovskites is possible for opto-electronic device manufacturing on D surfaces. It is believed that this work paves the way for the fabrication of previously unimaginable opto-electronic devices by additive manufacturing

    Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70M>70 MM_\odot) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e0.30 < e \leq 0.3 at 0.330.33 Gpc3^{-3} yr1^{-1} at 90\% confidence level.Comment: 24 pages, 5 figure

    Open data from the third observing run of LIGO, Virgo, KAGRA and GEO

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    The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in April of 2019 and lasting six months, O3b starting in November of 2019 and lasting five months, and O3GK starting in April of 2020 and lasting 2 weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main dataset, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.Comment: 27 pages, 3 figure
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