1,311 research outputs found

    Covert Communications in the RF Band of Primary Wireless Networks

    Get PDF
    Covert systems are designed to operate at a low probability of detection (LPD) in order to provide system protection at the physical layer level. The classical approach to covert communications aims at hiding the covert signal in noise by lowering the power spectral density of the signal to a level that makes it indistinguishable from that of the noise. However, the increasing demand for modern covert systems that can provide better protection against intercept receivers (IRs) and provides higher data rates has shifted the focus to the design of Ad-Hoc covert networks (ACNs) that can hide their transmission in the RF spectrum of primary networks (PNs), like mobile networks. The early work on exploiting the RF band of other wireless systems has been promising; however, the difficulties in modeling such environments, analyzing the impact on/from the primary network, and deriving closed form expressions for the performance of the covert network have limited the work on this crucial subject. In this work, we provide the first comprehensive analyses of a covert network that exploits the RF band of an OFDM-based primary network to achieve covertness. A spectrum access algorithm is presented which would allow the ACN to transmit in the RF spectrum of the PN with minimum interference. Next, we use stochastic geometry to model both the OFDM-based PN as well as the ACN. Using stochastic geometry would also allow us to derive closed-form expressions and provide a comprehensive analysis for two metrics, namely an aggregate metric and a ratio metric. These two metrics quantify the covertness and performance of the covert network from the perspective of the IR and the ACN, respectively. The two metrics are used to determine the detectability limits of an ACN by an IR. The two metrics along with the proposed spectrum access algorithm will be used to provide a comprehensive discussion on how to design the ACN for a target covertness level, and analyze the effect of the PN parameters on the ACN expected performance. This work also addresses the question of trade-off between the ACN covertness and its achievable throughput. The overall discussion and results in this research work illustrate the strong potential for using man-made transmissions as a mask for covert communications. In addition, some of our results can be directly used for other applications such as device-to-device (D2D) and vehicle-to-everything (V2X) communications

    IMF Financial Stability Report: Republic of Korea

    Get PDF

    Republic of Korea financial system stability assessment

    Get PDF

    Combined RASSF1A and RASSF2A Promoter Methylation Analysis as Diagnostic Biomarker for Bladder Cancer

    Get PDF
    Promoter hypermethylation, a widely studied epigenetic event known to influence gene expression levels, has been proposed as a potential biomarker in multiple types of cancer. Clinical diagnostic biomarkers are needed for reliable prediction of bladder cancer recurrence. In this paper, DNA promoter methylation of five C-terminal Ras-association family members (RASSF1A, RASSF2A, RASSF4, RASSF5, and RASSF6) was studied in 64 formalin-fixed paraffin-embedded (FFPE) bladder cancer and normal adjacent tissues using methylation-specific high-resolution melting (MS-HRM) analysis. Results showed that 73% (30/41) of transitional cell carcinoma, 100% (3/3) of squamous cell carcinoma, and 100% (4/4) of small cell carcinoma demonstrated promoter methylation of the RASSF1A or RASSF2A gene, but only 6% (1/16) of normal tissues had promoter methylation of RASSF genes. Testing positive for hypermethylation of RASSF1A or RASSF2A promoter provided 77% sensitivity and 94% specificity for identification of cancer tissues with an area under the curve of 0.854, suggesting that promoter methylation analysis of RASSF1A and RASSF2A genes has potential for use as a recurrence biomarker for bladder cancer patients

    Lack of awareness of erectile dysfunction in many men with risk factors for erectile dysfunction

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Men with erectile dysfunction often have concurrent medical conditions. Conversely, men with these conditions may also have underlying erectile dysfunction. The prevalence of unrecognized erectile dysfunction in men with comorbidities commonly associated with erectile dysfunction was determined in men invited to participate in a double-blind, randomized, placebo-controlled trial of sildenafil citrate.</p> <p>Methods</p> <p>Men ≥30 years old presenting with ≥1 erectile dysfunction risk factor (controlled hypertension, hypercholesterolemia, smoking, metabolic syndrome, stable coronary artery disease, diabetes, depression, lower urinary tract symptoms, obesity [body mass index ≥30 kg/m<sup>2</sup>] or waist circumference ≥40 inches), and not previously diagnosed with erectile dysfunction were evaluated. The screening question, "Do you have erectile dysfunction?," with responses of "no," "yes," and "unsure," and the Erectile Function domain of the International Index of Erectile Function (IIEF-EF) were administered.</p> <p>Results</p> <p>Of 1084 men screened, 1053 answered the screening question and also had IIEF-EF scores. IIEF-EF scores indicating erectile dysfunction occurred in 71% (744/1053), of whom 54% (399/744) had moderate or severe erectile dysfunction. Of 139 answering "yes," 526 answering "unsure," and 388 answering "no," 96%, 90%, and 36%, respectively, had some degree of erectile dysfunction. The mean±SD (range) number of risk factors was 2.9 ± 1.7 (3-8) in the "yes" group, 3.2 ± 1.7 (3-9) in the "unsure" group, and 2.6 ± 1.5 (2-8) in the "no" group.</p> <p>Conclusion</p> <p>Although awareness of having erectile dysfunction was low, most men with risk factors had IIEF-EF scores indicating erectile dysfunction. Erectile dysfunction should be suspected and assessed in men with risk factors, regardless of their apparent level of awareness of erectile dysfunction.</p> <p>Trial registration</p> <p>ClinicalTrials.gov Identifier NCT00343200.</p
    corecore