A Lightweight Secure and Resilient Transmission Scheme for the Internet of Things in the Presence of a Hostile Jammer

In this article, we propose a lightweight security scheme for ensuring both information confidentiality and transmission resiliency in the Internet-of-Things (IoT) communication. A single-Antenna transmitter communicates with a half-duplex single-Antenna receiver in the presence of a sophisticated multiple-Antenna-Aided passive eavesdropper and a multiple-Antenna-Assisted hostile jammer (HJ). A low-complexity artificial noise (AN) injection scheme is proposed for drowning out the eavesdropper. Furthermore, for enhancing the resilience against HJ attacks, the legitimate nodes exploit their own local observations of the wireless channel as the source of randomness to agree on shared secret keys. The secret key is utilized for the frequency hopping (FH) sequence of the proposed communication system. We then proceed to derive a new closed-form expression for the achievable secret key rate (SKR) and the ergodic secrecy rate (ESR) for characterizing the secrecy benefits of our proposed scheme, in terms of both information secrecy and transmission resiliency. Moreover, the optimal power sharing between the AN and the message signal is investigated with the objective of enhancing the secrecy rate. Finally, through extensive simulations, we demonstrate that our proposed system model outperforms the state-of-The-Art transmission schemes in terms of secrecy and resiliency. Several numerical examples and discussions are also provided to offer further engineering insights

Diagnostic accuracy of twinkling artifact sign seen in color doppler ultrasonography in detecting microlithiasis of kidney

Background: Ultrasonography (US) is a safe and cost-efficient modality which is used to assess patients with urinary tract lithiasis. Objectives: In this study, we aimed to evaluate the accuracy of the twinkling artifact of color Doppler sonography in detecting renal stones smaller than 4 mm in diameter. Methods: Of all patients referring to a tertiary medical center with a probable diagnosis of urolithiasis during April 2019 to Septem-ber 2019, 99 patients with a renal stone smaller than 4 mm in non-contrast computed tomography (CT) scan entered our study. Both gray scale and color Doppler US were performed to assess the presence of any renal stones, the accompanying posterior shadowing, and the twinkling artifact for all patients. Results: Of 99 patients with confirmed renal stone on non-contrast CT scan, 91 patients had an echogenic focus on grayscale (sensi-tivity = 91.9), 70 patients had posterior shadowing sign (sensitivity = 70.7), and 76 patients had twinkling artifact on color Doppler US. The sensitivity, specificity, positive predictive value, and negative predictive value of this imaging finding for detecting renal stones smaller than 4 mm were 76.8, 100, 100, and 32.4, respectively. Conclusions: Our study revealed that twinkling artifact on color Doppler US is a reliable sign for detecting renal stones smaller than 4 mm. However, the sensitivity of this sign could be increased in combination with gray scale findings (echogenic focus and posterior shadowing). © 2020, Author(s)