Coverless image steganography based on DenseNet feature mapping

Since the concept of coverless information hiding was proposed, it has been greatly developed due to its effectiveness of resisting the steganographic tools. Most existing coverless image steganography (CIS) methods achieve excellent robustness under non-geometric attacks. However, they do not perform well under some geometric attacks. Towards this goal, a CIS algorithm based on DenseNet feature mapping is proposed. Deep learning is introduced to extract high-dimensional CNN features which are mapped into hash sequences. For the sender, a binary tree hash index is built to accelerate index speed of searching hidden information and DenseNet hash sequence, and then, all matched images are sent. For the receiver, the secret information can be recovered successfully by calculating the DenseNet hash sequence of the cover image. During the whole steganography process, the cover images remain unchanged. Experimental results and analysis show that the proposed scheme has better robust compared with the state-of-the-art methods under geometric attacks.

Anticoagulation in patients with cardiac manifestations of Chagas disease and cardioembolic ischemic stroke

ABSTRACT Objectives To describe anticoagulation characteristics in patients with cardiac complications from Chagas disease and compare participants with and without cardioembolic ischemic stroke (CIS). Methods A retrospective cohort of patients with Chagas disease, using anticoagulation, conducted from January 2011 to December 2014. Results Forty-two patients with Chagas disease who were using anticoagulation were studied (age 62.9±12.4 years), 59.5% female and 47.6% with previous CIS, 78.6% with non-valvular atrial fibrillation and 69.7% with dilated cardiomyopathy. Warfarin was used in 78.6% of patients and dabigatran (at different times) in 38%. In the warfarin group, those with CIS had more medical appointments per person-years of follow-up (11.7 vs 7.9), a higher proportion of international normalized ratios within the therapeutic range (57% vs 42% medical appointments, p = 0.025) and an eight times higher frequency of minor bleeding (0.64 vs 0.07 medical appointments). Conclusion Patients with Chagas disease and previous CIS had better control of INR with a higher frequency of minor bleeding.