56 research outputs found
Opportunistic Wiretapping/Jamming: A New Attack Model in Millimeter-Wave Wireless Networks
While the millimeter-wave (mmWave) communication is robust against the
conventional wiretapping attack due to its short transmission range and
directivity, this paper proposes a new opportunistic wiretapping and jamming
(OWJ) attack model in mmWave wireless networks. With OWJ, an eavesdropper can
opportunistically conduct wiretapping or jamming to initiate a more hazardous
attack based on the instantaneous costs of wiretapping and jamming. We also
provide three realizations of the OWJ attack, which are mainly determined by
the cost models relevant to distance, path loss and received power,
respectively. To understand the impact of the new attack on mmWave network
security, we first develop novel approximation techniques to characterize the
irregular distributions of wiretappers, jammers and interferers under three OWJ
realizations. With the help of the results of node distributions, we then
derive analytical expressions for the secrecy transmission capacity to depict
the network security performance under OWJ. Finally, we provide extensive
numerical results to illustrate the effect of OWJ and to demonstrate that the
new attack can more significantly degrade the network security performance than
the pure wiretapping or jamming attack
Single-cell gene profiling of human regulatory T cell subsets in human graft-versus-host disease
International audiencen.
APT Weighted MRI as an Effective Imaging Protocol to Predict Clinical Outcome After Acute Ischemic Stroke
To explore the capability of the amide-proton-transfer weighted (APTW) magnetic resonance imaging (MRI) in the evaluation of clinical neurological deficit at the time of hospitalization and assessment of long-term daily functional outcome for patients with acute ischemic stroke (AIS). We recruited 55 AIS patients with brain MRI acquired within 24–48 h of symptom onset and followed up with their 90-day modified Rankin Scale (mRS) score. APT weighted MRI was performed for all the study subjects to measure APTW signal quantitatively in the acute ischemic area (APTWipsi) and the contralateral side (APTWcont). Change of the APT signal between the acute ischemic region and the contralateral side (ΔAPTW) was calculated. Maximum APTW signal (APTWmax) and minimal APTW signal (APTWmin) were also acquired to demonstrate APTW signals heterogeneity (APTWmax−min). In addition, all the patients were divided into 2 groups according to their 90-day mRS score (good prognosis group with mRS score <2 and poor prognosis group with mRS score ≥2). In the meantime, ΔAPTW of these groups was compared. We found that ΔAPTW was in good correlation with National Institutes of Health Stroke Scale (NIHSS) score (R2 = 0.578, p < 0.001) and 90-day mRS score (R2 = 0.55, p < 0.001). There was significant difference of ΔAPTW between patients with good prognosis and patients with poor prognosis. Plus, APTWmax−min was significantly different between two groups. These results suggested that APT weighted MRI could be used as an effective tool to assess the stroke severity and prognosis for patients with AIS, with APTW signal heterogeneity as a possible biomarker
Exploring Relay Cooperation for Secure and Reliable Transmission in Two-HopWireless Networks
This work considers the problem of secure and reliable information transmission via relay cooperation in two-hop relay wireless networks without the information of both eavesdropper channels and locations. While previous work on this problem mainly studied infinite networks and their asymptotic behavior and scaling law results, this papers focuses on a more practical network with finite number of system nodes and explores the corresponding exact result on the number of eavesdroppers one network can tolerate to ensure desired secrecy and reliability. We first study the scenario where path-loss is equal between all pairs of nodes and consider two transmission protocols there, one adopts an optimal but complex relay selection process with less load balance capacity while the other adopts a random but simple relay selection process with good load balance capacity. Theoretical analysis and numerical results are then provided to determine the maximum number of eavesdroppers one network can tolerate to ensure a desired performance in terms of the secrecy outage probability and transmission outage probability. We further extend our study to the more general scenario where path-loss between each pair of nodes also depends on the distance between them, for which a new transmission protocol with both preferable relay selection and good load balance as well as the corresponding theoretical analysis and numerical results are presented
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