In cache-enabled device-to-device (D2D) -aided cellular networks, the technique of caching contents in the cooperative crossing between base stations (BSs) and devices can significantly reduce core traffic and enhance network capacity. In this paper, we propose a scheme that establishes device availability, which indicates whether a cache-enabled device can handle the transmission of the desired content within the required sending time, called the delay, while achieving optimal probabilistic caching. We also investigate the impact of transmission device availability on the effectiveness of a scenario of cooperative crossing cache placement, where content delivery traffic can be offloaded from the local cache, a D2D transmitter’s cache via a D2D link, or else directly from a BS via a cellular link, in order to maximize the offloading probability. Further, we derive the cooperation content offloading strategy while considering successful content transmission by D2D transmitters or BSs to guarantee the delay, even though reducing the delay is not the focus of this study. Finally, the proposed problem is formulated. Owing to the non-convexity of the optimization problem, it can be rewritten as a minimization of the difference between the convex functions; thus, it can be solved by difference of convex (DC) programming using a low-complexity algorithm. Simulation results show that the proposed cache placement scheme improves the offloading probability by 13.5% and 23% compared to Most Popular Content (MPC) scheme, in which both BSs and devices cache the most popular content and Coop. BS/D2D caching scheme, in which each BS tier and user tier applies cooperative content caching separately.

Caching content by users constitutes a promising solution to decrease the costly transmissions with going through the base stations (BSs). To improve the performance of in-network caching in device-to-device (D2D) communications, caching placement and content delivery should be jointly optimized. To this end, we jointly optimize caching decision and content discovery strategies by considering the successful content delivery in D2D links for maximizing the in-network caching gain through D2D communications. Moreover, an in-network caching placement problem is formulated as an integer nonlinear optimization problem. To obtain the optimal solution for the proposed problem, Lagrange dual decomposition is applied in order to reduce the complexity. Simulation results show that the proposed algorithm has a near-optimal performance, approaching that of the exhaustive search method. Furthermore, the proposed scheme has a notable in-network caching gain and an improvement in traffic offloading compared to that of other caching placement schemes.

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Background: Helicobacter pylori (H. pylori) has various strains associated with human infections. H. pylori, H. heilmannii, and H. felis are the most common strains in humans. H. pylori is associated with several human diseases such as chronic gastritis, peptic ulcer, mucous membrane lymphoma, and gastric adenocarcinoma. This study aimed to determine the prevalence rates of H. felis and H. heilmannii and the effect of co-infection with H. pylori in gastric biopsy specimens of patients. Methods: Totally, 80 gastric biopsy specimens were taken by a physician from the patients referred to Shahid Beheshti Hospital, Hamadan City, Iran. PCR test was used to confirm the presence of H. pylori in samples that had positive rapid urease tests. Moreover, the ureB gene and ureA and ureB genes were used for H. heilmannii and H. felis, respectively. Results: Of the study patients, 61.5% were females, and 38.5% were males with a mean age of 37.8 years. Of 80 biopsies, 50% were H. pylori-positive, 53.8% were H. heilmannii-positive, but no H. felis was identified in any sample. Results indicate that smoking, having a history of gastrointestinal diseases, and taking certain medications can be risk factors for H. pylori. Conclusion: Any agent contributing to gastric mucosal damage can enhance the susceptibility to bacterial contamination. Overall, the results indicate a low probability of interactions between H. pylori, H. heilmannii, and H. felis.

Background: Helicobacter pylori (H. pylori) has various strains associated with human infections. H. pylori, H. heilmannii, and H. felis are the most common strains in humans. H. pylori is associated with several human diseases such as chronic gastritis, peptic ulcer, mucous membrane lymphoma, and gastric adenocarcinoma. This study aimed to determine the prevalence rates of H. felis and H. heilmannii and the effect of co-infection with H. pylori in gastric biopsy specimens of patients. Methods: Totally, 80 gastric biopsy specimens were taken by a physician from the patients referred to Shahid Beheshti Hospital, Hamadan City, Iran. PCR test was used to confirm the presence of H. pylori in samples that had positive rapid urease tests. Moreover, the ureB gene and ureA and ureB genes were used for H. heilmannii and H. felis, respectively. Results: Of the study patients, 61.5% were females, and 38.5% were males with a mean age of 37.8 years. Of 80 biopsies, 50% were H. pylori-positive, 53.8% were H. heilmannii-positive, but no H. felis was identified in any sample. Results indicate that smoking, having a history of gastrointestinal diseases, and taking certain medications can be risk factors for H. pylori. Conclusion: Any agent contributing to gastric mucosal damage can enhance the susceptibility to bacterial contamination. Overall, the results indicate a low probability of interactions between H. pylori, H. heilmannii, and H. felis.