254 research outputs found

    Exploring Cybersecurity Education at the K-12 Level

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    K-12 cybersecurity education is receiving growing attention with the growing number of cyberattacks and a shortage of cybersecurity professionals. However, there are many barriers for teachers to implement effective cybersecurity education in formal classroom environments. This study conducts a systematic literature review to examine the current state-of-the-art on K-12 cybersecurity education. Through the systematic literature review, we identified 20 closely relevant papers and recognized that a well-designed curriculum in cybersecurity education at the K-12 level is strongly needed to motivate students to pursue cybersecurity pathways and careers. The challenge and suggestions of curriculum design, teaching strategy, and learning assessment are summarized and discussed

    Automated Clustering Algorithms for Classification of Astronomical Objects

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    Data mining is an important and challenging problem for the efficient analysis of large astronomical databases and will become even more important with the development of the Global Virtual Observatory. In this study, learning vector quantization (LVQ), single-layer perceptron (SLP) and support vector machines (SVM) were put forward for multi-wavelength data classification. A feature selection technique was used to evaluate the significance of the considered features to the results of classification. From the results, we conclude that in the situation of less features, LVQ and SLP show better performance. In contrast, SVM shows better performance when considering more features. The focus of the automatic classification is on the development of efficient feature-based classifier. The classifiers trained by these methods can be used for preselecting AGN candidates.Comment: Accepted for publication in A&

    5-Hydroxymethylation marks a class of neuronal gene regulated by intragenic methylcytosine levels.

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    AbstractWe recently identified a class of neuronal gene inheriting high levels of intragenic methylation from the mother and maintaining this through later development. We show here that these genes are implicated in basic neuronal functions such as post-synaptic signalling, rather than neuronal development and inherit high levels of 5mC, but not 5hmC, from the mother. 5mC is distributed across the gene body and appears to facilitate transcription, as transcription is reduced in DNA methyltransferase I (Dnmt1) knockout embryonic stem cells as well as in fibroblasts treated with a methyltransferase inhibitor. However in adult brain, transcription is more closely associated with a gain in 5hmC, which occurs without a measurable loss of 5mC. These findings add to growing evidence that there may be a role for 5mC in promoting transcription as well as its classical role in gene silencing

    Exaggerated inflammation, impaired host defense, and neuropathology in progranulin-deficient mice

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    Progranulin (PGRN) is a widely expressed protein involved in diverse biological processes. Haploinsufficiency of PGRN in the human causes tau-negative, ubiquitin-positive frontotemporal dementia (FTD). However, the mechanisms are unknown. To explore the role of PGRN in vivo, we generated PGRN-deficient mice. Macrophages from these mice released less interleukin-10 and more inflammatory cytokines than wild type (WT) when exposed to bacterial lipopolysaccharide. PGRN-deficient mice failed to clear Listeria monocytogenes infection as quickly as WT and allowed bacteria to proliferate in the brain, with correspondingly greater inflammation than in WT. PGRN-deficient macrophages and microglia were cytotoxic to hippocampal cells in vitro, and PGRN-deficient hippocampal slices were hypersusceptible to deprivation of oxygen and glucose. With age, brains of PGRN-deficient mice displayed greater activation of microglia and astrocytes than WT, and their hippocampal and thalamic neurons accumulated cytosolic phosphorylated transactivation response element DNA binding protein–43. Thus, PGRN is a key regulator of inflammation and plays critical roles in both host defense and neuronal integrity. FTD associated with PGRN insufficiency may result from many years of reduced neutrotrophic support together with cumulative damage in association with dysregulated inflammation

    A Mutation in Intracellular Loop 4 Affects the Drug-Efflux Activity of the Yeast Multidrug Resistance ABC Transporter Pdr5p

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    Multidrug resistance protein Pdr5p is a yeast ATP-binding cassette (ABC) transporter in the plasma membrane. It confers multidrug resistance by active efflux of intracellular drugs. However, the highly polymorphic Pdr5p from clinical strain YJM789 loses its ability to expel azole and cyclohexmide. To investigate the role of amino acid changes in this functional change, PDR5 chimeras were constructed by segmental replacement of homologous BY4741 PDR5 fragments. Functions of PDR5 chimeras were evaluated by fluconazole and cycloheximide resistance assays. Their expression, ATPase activity, and efflux efficiency for other substrates were also analyzed. Using multiple lines of evidence, we show that an alanine-to-methionine mutation at position 1352 located in the predicted short intracellular loop 4 significantly contributes to the observed transport deficiency. The degree of impairment is likely correlated to the size of the mutant residue

    Preoperative external beam radiotherapy and reduced dose brachytherapy for carcinoma of the cervix: survival and pathological response

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    PURPOSE: To evaluate the pathologic response of cervical carcinoma to external beam radiotherapy (EBRT) and high dose rate brachytherapy (HDRB) and outcome. MATERIALS AND METHODS: Between 1992 and 2001, 67 patients with cervical carcinoma were submitted to preoperative radiotherapy. Sixty-five patients were stage IIb. Preoperative treatment included 45 Gy EBRT and 12 Gy HDRB. Patients were submitted to surgery after a mean time of 82 days. Lymphadenectomy was performed in 81% of patients. Eleven patients with residual cervix residual disease on pathological specimen were submitted to 2 additional insertions of HDRB. RESULTS: median follow up was 72 months. Five-year cause specific survival was 75%, overall survival 65%, local control 95%. Complete pelvic pathological response was seen in 40%. Surgery performed later than 80 days was associated with pathological response. Pelvic nodal involvement was found in 12%. Complete pelvic pathological response and negative lymphnodes were associated with better outcome (p = .03 and p = .005). Late grade 3 and 4 urinary and intestinal adverse effects were seen in 12 and 2% of patients. CONCLUSION: Time allowed between RT and surgery correlated with pathological response. Pelvic pathological response was associated with improved outcome. Postoperative additional HDRB did not improve therapeutic results. Treatment was well tolerated

    Scientific Prospects for Hard X-ray Polarimetry

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    X-ray polarimetry promises to give qualitatively new information about high-energy sources. Examples of interesting source classes are binary black hole systems, rotation and accretion powered neutron stars, Microquasars, Active Galactic Nuclei and Gamma-Ray Bursts. Furthermore, X-ray polarimetry affords the possibility for testing fundamental physics, e.g. to observe signatures of light bending in the strong gravitational field of a black hole, to detect third order Quantum Electrodynamic effects in the magnetosphere of Magnetars, and to perform sensitive tests of Lorentz Invariance. In this paper we discuss scientific drivers of hard (>10 keV) X-ray polarimetry emphasizing how observations in the hard band can complement observations at lower energies (0.1 - 10 keV). Subsequently, we describe four different technical realizations of hard X-ray polarimeters suitable for small to medium sized space borne missions, and study their performance in the signal-dominated case based on Monte Carlo simulations. We end with confronting the instrument requirements for accomplishing the science goals with the capabilities of the four polarimeters.Comment: Accepted for publication in Astroparticle Physic

    Stock markets and effective exchange rates in European countries: threshold cointegration findings

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    © 2015, Eurasia Business and Economics Society. The nexus between stock markets and exchange rates is examined in the case of eight European countries. The sample consists of four economies with national currencies and four that have adopted the euro. Thus, if differences between the two groups in the relationship governing the two markets exist, they will be unveiled. To this effect, a threshold cointegration methodology is adopted that allows for more reliable inferences to be drawn for both the short and long run nexus between the two markets. Monthly data is used covering the period 01/2000–12/2014. The findings reported herein offer support in favor of the portfolio approach thesis over the recent economic crisis period, but this finding is not the case for the entire sample. Bidirectional causality is found for Norway and the UK, pointing to a currency effect on stock markets. In view of the findings reported herein, policies aiming at reducing uncertainty in the stock markets can exert beneficial effects on currency markets

    Gyroid-Forming Diblock Copolymers Confined in Cylindrical Geometry: A Case of Extreme Makeover for Domain Morphology

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    The self-assembly of gyroid-forming diblock copolymers confined in cylindrical geometry is studied using a combination of computer simulations and experiments. The simulations, based on a system qualitatively representative of poly(styrene-b-isoprene), are performed with cylindrical nanopores of different diameter (D) and surface selectivity. The effects of the pore size and surface selectivity on morphology are systematically investigated. Different morphological sequences are predicted for two gyroid-forming diblock copolymers. The experiments are carried out on two gyroid-forming poly(styrene-b-dimethylsiloxane) block copolymer samples confined in the core of continuous core−shell nanofibers of different diameters, which are obtained by a coaxial two-fluid electrospinning technique. The internal microphase-separated morphologies of these fibers are investigated by transmission electron microscopy (TEM). Both simulations and experiments demonstrate that a rich variety of structures spontaneously form for the gyroid-forming diblock copolymers, depending on the conditions of cylindrical confinement. Many of these confinement-induced structures are quite different from those of cylinder-forming or lamella-forming block copolymers. Simulations further show that these structures depend sensitively on the block copolymer composition, surface selectivity, and the ratio D/L0 where L0 is the period of the equilibrium gyroid phase. While the simulation and experimental systems are representative of different chemistries, the morphological predictions of simulations are qualitatively consistent with the experimental observations.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract DAAD-19-02-D-0002)United States. Army Research Offic

    Spatiotemporal neural characterization of prediction error valence and surprise during reward learning in humans

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    Reward learning depends on accurate reward associations with potential choices. These associations can be attained with reinforcement learning mechanisms using a reward prediction error (RPE) signal (the difference between actual and expected rewards) for updating future reward expectations. Despite an extensive body of literature on the influence of RPE on learning, little has been done to investigate the potentially separate contributions of RPE valence (positive or negative) and surprise (absolute degree of deviation from expectations). Here, we coupled single-trial electroencephalography with simultaneously acquired fMRI, during a probabilistic reversal-learning task, to offer evidence of temporally overlapping but largely distinct spatial representations of RPE valence and surprise. Electrophysiological variability in RPE valence correlated with activity in regions of the human reward network promoting approach or avoidance learning. Electrophysiological variability in RPE surprise correlated primarily with activity in regions of the human attentional network controlling the speed of learning. Crucially, despite the largely separate spatial extend of these representations our EEG-informed fMRI approach uniquely revealed a linear superposition of the two RPE components in a smaller network encompassing visuo mnemonic and reward areas. Activity in this network was further predictive of stimulus value updating indicating a comparable contribution of both signals to reward learning
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