The Effect of Opioid Receptor Blockade on the Neural Processing of Thermal Stimuli

The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent) signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone

Design and Analysis of New Version of Cryptographic Hash Function Based on Improved Chaotic Maps With Induced DNA Sequences

One of the first and most used hashing algorithms in blockchains is SHA-256 so the main aim of this paper is how to increase the security level of the blockchain based on the increasing hashing algorithm security. This paper proposes to present a modified SHA-256 like hash algorithm by exploring the design principles of the two hash schemes (SHA-256 and RIPEMD-160). To retrieve the increased security in the proposed algorithm, we modify the SHA-256 after the public key generation. The proposed modification is based on four different chosen types of chaotic maps and DNA sequences which eventually complicate the association between the original message and hash digest i.e., maximizing the security level, and minimizing its vulnerabilities. The proposed hash function efficiency is practically assessed, analyzed, and compared with the well-known SHA-256 with respect to the main properties of the confusion, diffusion and distribution. The security performance is also analyzed using the analysis of collision, which reveals that the new constructed hash function improves SHA-256 with respect to the security and robustness. From the experimental analyses results, the proposed modified hash scheme found to exhibit the better security performance than many state-of-the art existing hash function schemes