The diagnostic accuracy of single photon emission computed tomography (SPECT) is profoundly influenced by attenuation phenomenon. Soft tissue attenuation degrades cardiac SPECT image quality, thereby decreasing the possibility of the detection of the lesions. A variety of correction techniques based on different assumptions have been used to reduce the impact of attenuation. Several types of sy...

We consider a signaling format where information is modulated via a superposition of independent data streams. Each data stream is formed by error-correction encoding, constellation mapping, replication and permutation of symbols, and application of signature sequences. The relations between data bits and the modulation symbols transmitted over the channel can be represented in the form of a sp...

Providing connectivity in scenarios where nodes present a very dynamic behavior is quite challenging due to resulting link intermittency among user devices. In such a challenged scenario, opportunistic contacts can be used to perform data forwarding. Moreover, as these moving nodes are carried by humans, taking into account the users' interests, social relationships, and mobility behavior may p...